SURFACE-COATED CUTTING TOOL IN WHICH HARD COATING LAYER EXHIBITS EXCELLENT CHIPPING RESISTANCE
20170297117 · 2017-10-19
Assignee
Inventors
Cpc classification
B23B27/148
PERFORMING OPERATIONS; TRANSPORTING
C23C16/0272
CHEMISTRY; METALLURGY
B23B2222/28
PERFORMING OPERATIONS; TRANSPORTING
C23C28/42
CHEMISTRY; METALLURGY
C23C28/044
CHEMISTRY; METALLURGY
B23B2228/04
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
A surface-coated cutting tool has a hard coating layer on a tool body. The hard coating layer includes a (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layer (the average amount Xavg of Al and the average amount Yavg of C satisfy 0.60≦Xavg≦0.95 and 0≦Yavg≦0.005). Crystal grains having an NaCl type face-centered cubic structure in the layer have {111} orientation, a columnar structure in which the average grain width of the individual crystal grains having an NaCl type face-centered cubic structure is 0.1 μm to 2.0 μm and the average aspect ratio is 2 to 10 is included, and in the individual crystal grains having an NaCl type face-centered cubic structure, a periodic compositional variation in Ti and Al in the composition formula: (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) is present and the difference between the average of maximum values of x and the average of minimum values thereof is 0.03 to 0.25.
Claims
1. A surface-coated cutting tool comprises: a tool body that is made of any of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, and a cubic boron nitride-based ultrahigh-pressure sintered body; and a hard coating layer that is provided on a surface of the tool body, wherein (a) the hard coating layer includes at least a layer of a complex nitride or complex carbonitride of Ti and Al, the layer being formed to an average layer thickness of 1 μm to 20 μm in a chemical vapor deposition method, and in a case where the layer is expressed by the composition formula: (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y), an average amount Xavg of Al of the layer of a complex nitride or complex carbonitride in a total amount of Ti and Al and an average amount Yavg of C in a total amount of C and N (both Xavg and Yavg are atomic ratios) respectively satisfy 0.60≦Xavg≦0.95 and 0≦Yavg≦0.005, (b) the layer of a complex nitride or complex carbonitride includes at least a phase of a complex nitride or complex carbonitride having an NaCl type face-centered cubic structure, (c) regarding the layer of a complex nitride or complex carbonitride, in a case where crystal orientations of individual crystal grains having an NaCl type face-centered cubic structure in the layer of a complex nitride or complex carbonitride in a longitudinal sectional direction of the layer of a complex nitride or complex carbonitride are analyzed using an electron backscatter diffraction apparatus, when an inclined angle frequency distribution is obtained by measuring inclined angles of normal lines of {111} planes which are crystal planes of the crystal grains with respect to a normal direction of the surface of the tool body, dividing inclined angles in a range of 0 degrees to 45 degrees with respect to the normal direction among the measured inclined angles into intervals of 0.25 degrees, and aggregating frequencies in the respective divisions, a highest peak is present in an inclined angle division in a range of 0 degrees to 10 degrees, and a sum of frequencies that are present in the range of 0 degrees to 10 degrees has a proportion of 45% or higher of a total of the frequencies in the inclined angle frequency distribution, (d) regarding the layer of a complex nitride or complex carbonitride, in a case where the layer is observed in the longitudinal sectional direction, a columnar structure in which an average grain width W of the individual crystal grains having an NaCl type face-centered cubic structure in the layer of a complex nitride or complex carbonitride is 0.1 μm to 2.0 μm and an average aspect ratio A thereof is 2 to 10 is included, and (e) in the individual crystal grains having an NaCl type face-centered cubic structure in the layer of a complex nitride or complex carbonitride, a periodic compositional variation in Ti and Al in the (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) is present along one orientation among equivalent crystal orientations expressed by <001>of the crystal grains, and a difference Ax between an average of maximum values of x which varies periodically and an average of minimum values thereof is 0.03 to 0.25.
2. The surface-coated cutting tool according to claim 1, wherein, in the crystal grains having an NaCl type face-centered cubic structure in which the periodic compositional variation in Ti and Al is present in the layer of a complex nitride or complex carbonitride, the periodic compositional variation in Ti and Al is present along one orientation among the equivalent crystal orientations expressed by <001> of the crystal grains, a period along the orientation is 3 nm to 100 nm, and compositional variation XO of Al in a plane perpendicular to the orientation in a total amount of Ti and Al is 0.01 or less.
3. The surface-coated cutting tool according to claim 1, wherein, regarding the layer of a complex nitride or complex carbonitride, lattice constants a of the crystal grains having an NaCl type face-centered cubic structure are obtained from X-ray diffraction, and the lattice constants a of the crystal grains having an NaCl type face-centered cubic structure satisfy a relationship of 0.05a.sub.TiN+0.95a.sub.AlN≦a≦0.4a.sub.TiN+0.6a.sub.AlN for a lattice constant a.sub.TiN of cubic TiN and a lattice constant a.sub.AlN of cubic AlN.
4. The surface-coated cutting tool according to claim 1, wherein the layer of a complex nitride or complex carbonitride is formed of a single phase of a complex nitride or complex carbonitride of Ti and Al having an NaCl type face-centered cubic structure.
5. The surface-coated cutting tool according to claim 1, wherein, regarding the layer of a complex nitride or complex carbonitride, in a case where the layer is observed in the longitudinal sectional direction, in grain boundaries of the columnar structure constituted by the individual crystal grains having an NaCl type face-centered cubic structure in the layer of a complex nitride or complex carbonitride, fine crystal grains having a hexagonal structure are present, an area proportion of the fine crystal grains present is 30% or lower by area, and an average grain size R of the fine crystal grains is 0.01 μm to 0.3 μm.
6. The surface-coated cutting tool according to claim 1, wherein, a lower layer is provided between the tool body and the layer of a complex nitride or complex carbonitride of Ti and Al, said lower layer being which is formed of a Ti compound layer that includes one layer or two or more layers of a Ti carbide layer, a Ti nitride layer, a Ti carbonitride layer, a Ti oxycarbide layer, and a Ti oxycarbonitride layer and has an average total layer thickness of 0.1 μm to 20 μm is present.
7. The surface-coated cutting tool according to claim 1, wherein an upper layer which includes an aluminum oxide layer having an average layer thickness of at least 1 μm to 25 μm is present in an upper portion of the layer of a complex nitride or complex carbonitride.
8. The surface-coated cutting tool according to claim 1, wherein the layer of a complex nitride or complex carbonitride is formed by a chemical vapor deposition method in which at least trimethylaluminum is contained as a reaction gas component.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein like designations denote like elements in the various views, and wherein:
[0054]
[0055]
[0056]
[0057]
[0058]
DETAILED DESCRIPTION OF THE INVENTION
[0059] Next, Examples of the coated tool of the present invention will be described in more detail.
EXAMPLE 1
[0060] As raw material powders, a WC powder, a TiC powder, a TaC powder, an NbC powder, a Cr.sub.3C.sub.2 powder, and a Co powder, all of which had an average grain size of 1 μm to 3 μm, were prepared, and the raw material powders were mixed in mixing compositions shown in Table 1. Wax was further added thereto, and the mixture was blended in acetone by a ball mill for 24 hours and was decompressed and dried. Thereafter, the resultant was press-formed into compacts having predetermined shapes at a pressure of 98 MPa, and the compacts were sintered in a vacuum at 5 Pa under the condition that the compacts were held at a predetermined temperature in a range of 1370° C. to 1470° C. for one hour. After the sintering, tool bodies A to C made of WC-based cemented carbide with insert shapes according to ISO standard SEEN1203AFSN were produced.
[0061] In addition, as raw material powders, a TiCN (TiC/TiN=50/50 in terms of mass ratio) powder, an Mo.sub.2C powder, a ZrC powder, an NbC powder, a WC powder, a Co powder, and an Ni powder, all of which had an average grain size of 0.5 μm to 2 μm, were prepared, and the raw material powders were mixed in mixing compositions shown in Table 2, were subjected to wet mixing by a ball mill for 24 hours, and were dried. Thereafter, the resultant was press-formed into compacts at a pressure of 98 MPa, and the compacts were sintered in a nitrogen atmosphere at 1.3 kPa under the condition that the compacts were held at a temperature of 1500° C. for one hour. After the sintering, a tool body D made of TiCN-based cermet with insert shapes according to ISO standard SEEN1203AFSN was produced.
[0062] Next, present invention coated tools 1 to 9 were produced by forming hard coating layers, which included a (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layer in which crystal grains having an NaCl type face-centered cubic structure with a periodic compositional variation in Ti and Al shown in Table 7 were present in an area proportion shown in Table 7 and which had a target layer thickness shown in Table 7, on the surfaces of the tool bodies A to D through a thermal CVD method for a predetermined time using a chemical vapor deposition apparatus under forming conditions A to I shown in Table 4 in which a gas group A of NH.sub.3, N.sub.2 and H.sub.2 and a gas group B of TiCl.sub.4, Al(CH.sub.3).sub.3, AlCl.sub.3, N.sub.2, and H.sub.2 were used and in each gas supply method, a reaction gas composition (% by volume with respect to the total amount of the gas group A and the gas group B) included a gas group A of NH.sub.3: 1.0% to 1.5%, N.sub.2: 0.0% to 5.0%, H.sub.2: 55% to 60% and a gas group B of AlCl.sub.3: 0.6% to 0.9%, TiCl.sub.4: 0.2% to 0.3%, Al(CH.sub.3).sub.3: 0% to 0.5%, N.sub.2: 0.0% to 12.0%, H.sub.2: the remainder, a reaction atmosphere pressure was 4.5 kPa to 5.0 kPa, a reaction atmosphere temperature was 700° C. to 900° C., a supply period was 1 second to 5 seconds, a gas supply time per one period was 0.15 seconds to 0.25 seconds, and a phase difference in supply between gas group A and gas group B was 0.10 seconds to 0.20 seconds.
[0063] In addition, any of a lower layer and an upper layer shown in Table 6 was formed on the present invention coated tools 3 to 9 under forming conditions shown in Table 3.
[0064] Regarding a layer of a complex nitride or complex carbonitride of Ti and Al included in the hard coating layers of the present invention coated tools 1 to 9, a plurality of visual fields were observed using a scanning electron microscope (at a magnification of 5000× and 20,000×). As illustrated in a film configuration schematic view in
[0065] In addition, it was confirmed through line analysis by energy-dispersive X-ray spectroscopy (EDS) using a transmission electron microscope (at a magnification of 200,000×) that a periodic compositional variation of Ti and Al was present in the crystal grains having an NaCl type face-centered cubic structure. As a result of more detailed analysis, it was confirmed that the difference between the average of the maximum values and the average of the minimum values x which is a periodic compositional variation in Ti and Al was 0.03 to 0.25.
[0066] In addition, for the purpose of comparison, like the present invention coated tools 1 to 9, hard coating layers including at least a layer of a complex nitride or complex carbonitride of Ti and Al were deposited on the surfaces of the tool bodies A to D to have a target layer thickness (μm) shown in
[0067] In addition, like the present invention coated tools 3 to 9, any of a lower layer and an upper layer shown in Table 6 was formed on the comparative coated tools 3 to 9 under the forming conditions shown in Table 3.
[0068] For reference, a reference coated tool 10 shown in Table 8 was produced by depositing (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layers of a reference example on the surfaces of the tool body B to have target layer thicknesses through arc ion plating using a physical vapor deposition apparatus in the related art.
[0069] In addition, conditions of the arc ion plating using the deposition of the reference example are as follows.
[0070] (a) The tool body B was subjected to ultrasonic cleaning in acetone and was dried. In this state, the tool body B was mounted along outer circumferential portions on a rotating table in an arc ion plating apparatus at positions distant from the center axis thereof by predetermined distances in a radial direction thereof, and an Al—Ti alloy having a predetermined composition was disposed as a cathode electrode (evaporation source).
[0071] (b) First, while the inside of the apparatus was evacuated and maintained in a vacuum at 10.sup.−2 Pa or lower, the inside of the apparatus was heated to 500° C. by a heater, and a DC bias voltage of −1000 V was thereafter applied to the tool body that was rotated while being revolved on the rotating table. In addition, arc discharge was generated by allowing a current of 200 A to flow between the cathode electrode made of the Al—Ti alloy and an anode electrode such that Al and Ti ions were generated in the apparatus and the surface of the tool body was subjected to bombard cleaning.
[0072] (c) Next, nitrogen gas as a reaction gas was introduced into the apparatus to form a reaction atmosphere at 4 Pa, and a DC bias voltage of −50 V was applied to the tool body that was rotated while being revolved on the rotating table. In addition, arc discharge was generated by allowing a current of 120 A to flow between the cathode electrode (evaporation source) made of the Al—Ti alloy and the anode electrode such that a (Ti,Al)N layer having a target composition and a target layer thickness shown in Table 8 was deposited on the surface of the tool body, thereby producing the reference coated tool 10.
[0073] The section of each of constituent layers of the present invention coated tools 1 to 9, the comparative coated tools 1 to 9, and the reference coated tool 10 was measured using a scanning electron microscope (at a magnification of 5000×). An average layer thickness was obtained by measuring and averaging the layer thicknesses of five points in an observation visual field. All of the results showed substantially the same average layer thicknesses as the target layer thicknesses shown in Tables 6 to 8.
[0074] In addition, regarding the average amount Xavg of Al of the layer of a complex nitride or complex carbonitride, a sample of which the surface was polished using an electron probe micro-analyzer (EPMA) was irradiated with electron beams from the sample surface side, and the average amount Xavg of Al was obtained by averaging 10 points of the analytic result of obtained characteristic X-rays. The average amount Yavg of C was obtained by secondary ion mass spectrometry (SIMS). Ion beams were emitted toward a range of 70 μm×70 μm from the sample surface side, and the concentration of components emitted by a sputtering action was measured in a depth direction. The average amount Yavg of C represents the average value in the depth direction of the layer of a complex nitride or complex carbonitride of Ti and Al. However, the amount of C excludes an unavoidable amount of C which is included even though gas containing C is not intentionally used as a gas raw material. Specifically, the amount (atomic ratio) of the component C contained in the layer of a complex nitride or complex carbonitride in a case where the amount of supplied Al(CH.sub.3).sub.3 was set to 0 was obtained as the unavoidable amount of C, and a value obtained by subtracting the unavoidable amount of C from the amount (atomic ratio) of the component C contained in the layer of a complex nitride or complex carbonitride obtained in a case where Al(CH.sub.3).sub.3 was intentionally supplied was selected to be Yavg.
[0075] In addition, regarding the present invention coated tools 1 to 9, the comparative coated tools 1 to 9, and the reference coated tool 10, in the individual crystal grains which were present in a range at a length of 10 μm in a direction parallel to the surface of the tool body in less than the film thickness of the layer of a complex nitride or complex carbonitride in a normal direction thereof and had an NaCl type face-centered cubic structure in the (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layer included in the layer of a complex nitride or complex carbonitride, grain widths w in the direction parallel to the surface of the body and grain lengths l in the direction perpendicular to the surface of the body were measured from a sectional direction in the direction perpendicular to the tool body using a scanning electron microscope (at a magnification of 5000× and 20,000×), the aspect ratio a(=l/w) of each of the crystal grains was calculated, the average value of the aspect ratios a obtained for the individual crystal grains was calculated as an average aspect ratio A, and the average value of the grain widths w obtained for the individual crystal grains was calculated as an average grain width W. Furthermore, the average grain size R of fine crystal grains that were present in the grain boundaries of a columnar structure constituted by the individual crystal grains having a cubic structure was also calculated. The results are shown in Tables 7 and 8.
[0076] In addition, regarding an inclination angle frequency distribution of the hard coating layer, in a state where the section of the hard coating layer including the layer of a complex nitride or complex carbonitride of Ti and Al in the direction perpendicular to the surface of the tool body was polished as a polished surface, the polished surface was set in the body tube of a field emission scanning electron microscope, and an electron beam was emitted toward each of the crystal grains having a cubic crystal lattice, which were present in a measurement range of the section polished surface at an incident angle of 70 degrees with respect to the section polished surface at an acceleration voltage of 15 kV and an emission current of 1 nA. Regarding the hard coating layer in a measurement range at a length of 100 μm in the direction parallel to the surface of the tool body in less than the film thickness along the section in the direction perpendicular to the surface of the tool body, inclined angles of normal lines of {111} planes which were crystal planes of the crystal grains with respect to the normal line (the direction perpendicular to the surface of the body in the section polished surface) of the surface of the body were measured using an electron backscatter diffraction imaging device at an interval of 0.01 μm/step. On the basis of the measurement results, measured inclined angles in a range of 0 degrees to 45 degrees among the measured inclined angles were divided into intervals of 0.25 degrees, frequencies in the respective divisions were aggregated, and the presence of the peaks of the frequencies present in a range of 0 degrees to 10 degrees was checked. In addition, the proportion of the frequencies present in the range of 0 degrees to 10 degrees was obtained. The results are also shown in Tables 7 and 8.
[0077] As an example,
[0078] In addition, in a state where the section of the hard coating layer including the layer of a complex nitride or complex carbonitride of Ti and Al in the direction perpendicular to the surface of the tool body was polished as a polished surface, the polished surface was set in the body tube of the field emission scanning electron microscope, and an electron beam was emitted toward each of the crystal grains which were present in the measurement range of the section polished surface at an incident angle of 70 degrees with respect to the section polished surface at an acceleration voltage of 15 kV and an emission current of 1 nA. Regarding the hard coating layer in a range at a length of 50 μm in the direction parallel to the tool body in less than the layer thickness of the layer of a complex nitride or complex carbonitride in the normal direction thereof, an electron backscatter diffraction image was measured using an electron backscatter diffraction apparatus device at an interval of 0.01 μm/step. By analyzing the crystal structure of the individual crystal grains, fine crystal grains that were present in the grain boundaries of a columnar structure constituted by the crystal grains having an NaCl type face-centered cubic structure were identified as a hexagonal structure, and the area proportion of the fine crystal grains was obtained. The results are also shown in Tables 7 and 8.
[0079] Furthermore, a small region of the layer of a complex nitride or complex carbonitride was observed by using the transmission electron microscope (at a magnification of 200,000×), and line analysis from the section side was performed using energy-dispersive X-ray spectroscopy (EDS). It was confirmed that a periodic compositional variation in Ti and Al was present in the composition formula: (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) in the crystal grains having an NaCl type face-centered cubic structure. In addition, through electron diffraction of the crystal grains, it was confirmed that the periodic compositional variation in Ti and Al was present along one orientation among equivalent crystal orientations expressed by <001> of the crystal grains having an NaCl type face-centered cubic structure. Line analysis through EDS along the orientation was performed, the difference between the average of maximum values of the periodic compositional variation in Ti and Al and the average of minimum values thereof was obtained as Δx, and furthermore, the period of the maximum values was obtained as the period of the periodic compositional variation in Ti and Al. Line analysis along a direction orthogonal to the orientation was performed, and the difference between the maximum value and the minimum value of the amount x of Al in the total amount of Ti and Al was obtained as a compositional variation XO in Ti and Al.
[0080] The results are also shown in Tables 7 and 8.
TABLE-US-00001 TABLE 1 Mixing composition (mass %) Type Co TiC TaC NbC Cr.sub.3C.sub.2 WC Tool A 8.0 1.5 — 3.0 0.4 Remainder body B 8.5 — 1.8 0.2 — Remainder C 7.0 — — — — Remainder
TABLE-US-00002 TABLE 2 Mixing composition (mass %) Type Co Ni ZrC NbC Mo.sub.2C WC TiCN Tool D 8 5 1 6 6 10 Remainder body
TABLE-US-00003 TABLE 3 Forming conditions (pressure of reaction atmosphere is expressed as Constituent layers of kPa and temperature is expressed as ° C.) hard coating layer Reaction Forma- Reaction gas atmosphere tion composition Pres- Temper- Type symbol (% by volume) sure ature (Ti.sub.1−xAl.sub.x) TiAlCN TiAlCN See Tables 4 and 5 (C.sub.yN.sub.1−y) layer Ti TiC TiC TiCl.sub.4: 4.0%, 7 1000 compound CH.sub.4: 7.5%, layer H.sub.2: remainder TiN TiN TiCl.sub.4: 4.0%, 30 780 N.sub.2: 30%, H.sub.2: remainder TiCN TiCN TiCl.sub.4: 2%, 7 780 CH.sub.3CN: 0.7%, N.sub.2: 10%, H.sub.2: remainder TiCNO TiCNO TiCl.sub.4: 1%, 7 780 CO: 0.5%, CO.sub.2: 1%, CH.sub.3CN: 1%, N.sub.2: 10%, H.sub.2: remainder Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 AlCl.sub.3: 1.2%, 7 800 layer CO.sub.2: 5.5%, HCl: 2.2%, H.sub.2S: 0.2%, H.sub.2: remainder
TABLE-US-00004 TABLE 4 Forming conditions (reaction gas composition indicates proportion in total amount of gas group A and gas group B, and pressure of reaction atmosphere is expressed as kPa and temperature is expressed as ° C.) Gas group A Gas group B Phase Supply Supply difference Formation of hard coating Reaction gas time Reaction gas time in supply layer group A Supply per one group B Supply per one between gas Process Formation composition period period composition period period group A and Reaction atmosphere type symbol (% by volume) (sec) (sec) (% by volume) (sec) (sec) gas group B Pressure Temperature Present A NH.sub.3: 1.0%, 1 0.2 AlCl.sub.3: 0.7%, TiCl.sub.4: 0.2%, 1 0.2 0.1 4.7 700 invention N.sub.2: 0.0%, N.sub.2: 0%, Al(CH.sub.3).sub.3: 0%, film H.sub.2: 55%, H.sub.2 as remainder forming B NH.sub.3: 1.0%, 3 0.15 AlCl.sub.3: 0.7%, TiCl.sub.4: 0.3%, 3 0.15 0.15 4.5 780 process N.sub.2: 5.0%, N.sub.2: 0%, Al(CH.sub.3).sub.3: 0.5%, H.sub.2: 60%, H.sub.2 as remainder C NH.sub.3: 1.5%, 2 0.25 AlCl.sub.3: 0.9%, TiCl.sub.4: 0.3%, 2 0.25 0.2 5 800 N.sub.2: 0.0%, N.sub.2: 0%, Al(CH.sub.3).sub.3: 0%, H.sub.2: 55%, H.sub.2 as remainder D NH.sub.3: 1.0%, 5 0.2 AlCl.sub.3: 0.6%, TiCl.sub.4: 0.2%, 5 0.2 0.1 4.7 800 N.sub.2: 1.0%, N.sub.2: 5%, Al(CH.sub.3).sub.3: 0%, H.sub.2: 55%, H.sub.2 as remainder E NH.sub.3: 1.5%, 4 0.2 AlCl.sub.3: 0.8%, TiCl.sub.4: 0.3%, 4 0.2 0.15 5 850 N.sub.2: 0.0%, N.sub.2: 9%, Al(CH.sub.3).sub.3: 0.2%, H.sub.2: 60%, H.sub.2 as remainder F NH.sub.3: 1.0%, 2.5 0.2 AlCl.sub.3: 0.7%, TiCl.sub.4: 0.3%, 2.5 0.2 0.2 4.5 750 N.sub.2: 2.5%, N.sub.2: 10%, Al(CH.sub.3).sub.3: 0%, H.sub.2: 55%, H.sub.2 as remainder G NH.sub.3: 1.0%, 1.5 0.15 AlCl.sub.3: 0.8%, TiCl.sub.4: 0.2%, 1.5 0.15 0.2 4.7 800 N.sub.2: 0.0%, N.sub.2: 12%, Al(CH.sub.3).sub.3: 0%, H.sub.2: 60%, H.sub.2 as remainder H NH.sub.3: 1.0%, 1.2 0.25 AlCl.sub.3: 0.9%, TiCl.sub.4: 0.2%, 1.2 0.25 0.1 4.7 900 N.sub.2: 3.5%, N.sub.2: 3%, Al(CH.sub.3).sub.3: 0%, H.sub.2: 60%, H.sub.2 as remainder I NH.sub.3: 1.5%, 4.5 0.2 AlCl.sub.3: 0.6%, TiCl.sub.4: 0.3%, 4.5 0.2 0.15 4.7 800 N.sub.2: 0.0%, N.sub.2: 7%, Al(CH.sub.3).sub.3: 0%, H.sub.2: 55%, H.sub.2 as remainder
TABLE-US-00005 TABLE 5 Forming conditions (reaction gas composition indicates proportion in total amount of gas group A and gas group B, and pressure of reaction atmosphere is expressed as kPa and temperature is expressed as ° C.) Gas group A Gas group B Phase Supply Supply difference Formation of hard coating Reaction gas time Reaction gas time in supply layer group A Supply per one group B Supply per one between gas Formation composition period period composition period period group A and Reaction atmosphere Process type symbol (% by volume) (sec) (sec) (% by volume) (sec) (sec) gas group B Pressure Temperature Comparative A′ NH.sub.3: 1.0%, — — AlCl.sub.3: 0.7%, TiCl.sub.4: 0.2%, — — — 4.7 700 film forming N.sub.2: 0.0%, N.sub.2: 0%, Al(CH.sub.3).sub.3: 0%, process H.sub.2: 55%, H.sub.2 as remainder B′ NH.sub.3: 1.0%, — — AlCl.sub.3: 0.7%, TiCl.sub.4: 0.3%, — — — 4.5 780 N.sub.2: 5.0%, N.sub.2: 0%, Al(CH.sub.3).sub.3: 0%, H.sub.2: 60%, H.sub.2 as remainder C′ NH.sub.3: 1.5%, — — AlCl.sub.3: 0.9%, TiCl.sub.4: 0.3%, — — — 5 800 N.sub.2: 0.0%, N.sub.2: 0%, Al(CH.sub.3).sub.3: 0.5%, H.sub.2: 55%, H.sub.2 as remainder D′ NH.sub.3: 1.0%, — — AlCl.sub.3: 0.6%, TiCl.sub.4: 0.2%, — — — 4.7 800 N.sub.2: 1.0%, N.sub.2: 5%, Al(CH.sub.3).sub.3: 0%, H.sub.2: 55%, H.sub.2 as remainder E′ NH.sub.3: 1.5%, — — AlCl.sub.3: 0.8%, TiCl.sub.4: 0.3%, — — — 5 850 N.sub.2: 3.0%, N.sub.2: 9%, Al(CH.sub.3).sub.3: 0%, H.sub.2: 60%, H.sub.2 as remainder F′ NH.sub.3: 1.0%, — — AlCl.sub.3: 0.7%, TiCl.sub.4: 0.3%, — — — 4.5 750 N.sub.2: 2.5%, N.sub.2: 10%, Al(CH.sub.3).sub.3: 0.2%, H.sub.2: 55%, H.sub.2 as remainder G′ NH.sub.3: 1.0%, — — AlCl.sub.3: 0.6%, TiCl.sub.4: 0.2%, — — — 4.7 800 N.sub.2: 0.0%, N.sub.2: 12%, Al(CH.sub.3).sub.3: 0%, H.sub.2: 60%, H.sub.2 as remainder H′ NH.sub.3: 1.0%, — — AlCl.sub.3: 0.9%, TiCl.sub.4: 0.2%, — — — 4.7 900 N.sub.2: 3.5%, N.sub.2: 3%, Al(CH.sub.3).sub.3: 0%, H.sub.2: 60%, H.sub.2 as remainder I′ NH.sub.3: 1.5%, — — AlCl.sub.3: 0.6%, TiCl.sub.4: 0.3%, — — — 4.7 800 N.sub.2: 2.0%, N.sub.2: 7%, Al(CH.sub.3).sub.3: 0.4%, H.sub.2: 55%, H.sub.2 as remainder
TABLE-US-00006 TABLE 6 Hard coating layer (numerical value at the bottom indicates target average layer thickness (μm)) Tool Lower layer Upper layer body First Second First Second Type symbol layer layer layer layer Present 1 A — — — — invention 2 D — — — — coated 3 B TiN — — — tool, (0.3) comparative 4 C TiN — — — coated (0.3) tool, 5 A TiN — — — reference (0.3) coated tool 6 D TiN — Al.sub.2O.sub.3 — (0.3) (2) 7 B TiN — TiCNO Al.sub.2O.sub.3 (0.3) (0.3) (1.5) 8 C TiC — — (0.5) 9 A TiN TiCN — — (0.3) (2)
TABLE-US-00007 TABLE 7 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) Division of Proportion of Formation Difference Dx inclined angles frequencies of 0 Average symbol of between average in which highest degrees to 10 de- grain TiAlCN of maximum values peak is present grees in inclined width W Tool film forming Average Average of x and an in inclined angle angle division in of cubic body process amount amount average of frequency distri- inclined angle fre- grains Type symbol (see Table 4) Xavg of Al Yavg of C minimum values bution (degrees) quency distribution (%) (mm) Present 1 A A 0.92 0.0001 or less 0.18 3.5 to 3.75 48.0 0.3 invention 2 D B 0.65 0.004 0.21 6.25 to 6.5 50.0 0.2 coated 3 B C 0.87 0.0001 or less 0.12 0.5 to 0.75 65.0 1.5 tool 4 C D 0.83 0.0001 or less 0.10 1.5 to 1.75 55.0 1.2 5 A E 0.78 0.0018 0.05 1.25 to 1.5 68.0 0.8 6 D F 0.68 0.0001 or less 0.14 0 to 0.25 75.0 0.5 7 B G 0.81 0.0001 or less 0.07 1.75 to 2.0 70.0 0.9 8 C H 0.75 0.0001 or less 0.04 5 to 5.25 80.0 0.8 9 A I 0.88 0.0001 or less 0.08 8.75 to 9.0 68.0 1.9 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) Average value Compositional vari- Lattice Area Average of periods of ation XO in amount constant proportion grain size Average compositional of Al in plane of grains of R of aspect change in Ti orthogonal to peri- having NaCl hexagonal hexagonal Target ratio A and Al along odic compositional type face- fine fine layer of cubic <001> orientation change along <001> centered cubic grains (% grains thickness Type grains (nm) orientation structure (Å) by area) (mm) (mm) Present 1 5.00 15 0.02 4.061 0 — 2.5 invention 2 8.00 35 0.01 or less 4.114 0 — 6.5 coated 3 3.50 45 0.01 or less 4.071 0 — 4 tool 4 4.50 25 0.01 or less 4.078 0 — 3.5 5 3.00 75 0.01 or less 4.088 15 0.15 5 6 4.00 10 0.01 or less 4.108 0 — 3 7 5.00 60 0.01 or less 4.082 0 — 6 8 6.00 25 0.01 or less 4.094 30.00 0.08 2 9 2.20 90 0.01 or less 4.069 0 — 4
TABLE-US-00008 TABLE 8 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) Division of Proportion of Formation inclined angles frequencies of 0 Average symbol of in which highest degrees to 10 de- grain Average TiAlCN peak is present grees in inclined width W aspect Tool film forming Average Average in inclined angle angle division in of cubic ratio A body process amount amount frequency distri- inclined angle fre- grains of cubic Type symbol (see Table 5) Xavg of Al Yavg of C bution (degrees) quency distribution (%) (mm) grains Comparative 1 A A′ 0.93 0.0001 or less 8.0 to 8.25 35.0 1.5 3 coated tool 2 D B′ 0.82 0.0001 or less 11.0 to 11.25 30.0 1.8 4 3 B C′ 0.65 0.008 22.25 to 22.5 18.0 1.2 1.2 4 C D′ 0.77 0.0001 or less 15.25 to 15.5 26.0 0.9 5 5 A E′ 0.94 0.0001 or less 18.75 to 19.sup. 33.0 2.2 2 6 D F′ 0.87 0.004 9.5 to 9.75 25.0 1.6 1.2 7 B G′ 0.64 0.0001 or less 31.25 to 31.5 26.0 0.8 3.5 8 C H′ 0.81 0.0001 or less 23.75 to 24.sup. 29.0 0.9 3.8 9 A I′ 0.78 0.0025 29.25 to 29.5 19.0 1.9 1.3 Reference 10 B AIP 0.48 — — — 1.2 3.5 coated tool Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) Average value Compositional vari- Lattice Area Average Difference Dx of periods of ation XO in amount constant proportion grain size between average compositional of Al in plane of grains of R of of maximum values change in Ti orthogonal to peri- having NaCl hexagonal hexagonal Target of x and an and Al along odic compositional type face- fine fine layer average of <001> orientation change along <001> centered cubic grains (% grains thickness Type minimum values (nm) orientation structure (Å) by area) (mm) (mm) Comparative 1 — — — 4.059 35 0.25 2.5 coated tool 2 — — — 4.080 3 0.04 6.5 3 — — — 4.114 10 0.23 4 4 — — — 4.090 5 0.18 3.5 5 — — — 4.057 12 0.23 5 6 — — — 4.071 28 0.35 3 7 — — — 4.116 16 0.12 6 8 — — — 4.082 32 0.21 2 9 — — — 4.088 18.0 0.2 4 Reference 10 — — — 4.147 — — 3.5 coated tool
[0081] Next, in a state in which each of the various coated tools was clamped to a cutter tip end portion made of tool steel with a cutter diameter of 125 mm by a fixing tool, the present invention coated tools 1 to 9, the comparative coated tools 1 to 9, and the reference coated tool 10 were subjected to dry high-speed face milling, which is a type of alloy steel high-speed intermittent cutting, and a center-cut cutting test, which are described below, and the flank wear width of a cutting edge was measured. The results are shown in Table 9.
[0082] Tool body: tungsten carbide-based cemented carbide, titanium carbonitride-based cermet
[0083] Cutting test: dry high-speed face milling, center-cut cutting
[0084] Work material: a JIS SCM440 block material with a width of 100 mm and a length of 400 mm
[0085] Rotational speed: 968 min.sup.−1
[0086] Cutting speed: 380 m/min
[0087] Depth of cut: 1.0 mm
[0088] Feed per edge: 0.1 mm/edge
[0089] Cutting time: 8 minutes
[0090] (a typical cutting speed is 220 m/min)
TABLE-US-00009 TABLE 9 Flank wear Cutting test Type width (mm) Type results (min) Present 1 0.22 Comparative 1 4.5* invention 2 0.28 coated tool 2 2.5* coated tool 3 0.15 3 6.8* 4 0.18 4 5.3* 5 0.27 5 3.1* 6 0.19 6 2.8* 7 0.26 7 3.6* 8 0.24 8 1.8* 9 0.17 9 7.2* Reference 10 2.1* coated tool Mark * in boxes of comparative coated tools and reference coated tools indicates a cutting time (min) until the end of a service life caused by the occurrence of chipping.
EXAMPLE 2
[0091] As raw material powders, a WC powder, a TiC powder, a ZrC powder, a TaC powder, an NbC powder, a Cr.sub.3C.sub.2 powder, a TiN powder, and a Co powder, all of which had an average grain size of 1 μm to 3 μm, were prepared, and the raw material powders were mixed in mixing compositions shown in Table 10. Wax was further added thereto, and the mixture was blended in acetone by a ball mill for 24 hours and was decompressed and dried. Thereafter, the resultant was press-formed into compacts having predetermined shapes at a pressure of 98 MPa, and the compacts were sintered in a vacuum at 5 Pa under the condition that the compacts were held at a predetermined temperature in a range of 1370° C. to 1470° C. for one hour. After the sintering, a cutting edge portion was subjected to honing to have a radius R of 0.07 mm, thereby forming tool bodies α to γ made of WC-based cemented carbide with insert shapes according to ISO standard CNMG120412.
[0092] In addition, as raw material powders, a TiCN (TiC/TiN=50/50 in terms of mass ratio) powder, an NbC powder, a WC powder, a Co powder, and an Ni powder, all of which had an average grain size of 0.5 μm to 2 μm, were prepared, and the raw material powders were mixed in mixing compositions shown in Table 11, were subjected to wet mixing by a ball mill for 24 hours, and were dried. Thereafter, the resultant was press-formed into compacts at a pressure of 98 MPa, and the compacts were sintered in a nitrogen atmosphere at 1.3 kPa under the condition that the compacts were held at a temperature of 1500° C. for one hour. After the sintering, a cutting edge portion was subjected to honing to have a radius R of 0.09 mm, thereby forming a tool body δ made of TiCN-based cermet with an insert shape according to ISO standard CNMG120412.
[0093] Subsequently, present invention coated tools 11 to shown in Table 13 were produced by depositing hard coating layers including at least a (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layer on the surfaces of the tool bodies α to γ and the tool body δ to have target layer thicknesses using a chemical vapor deposition apparatus under the conditions shown in Tables 3 and 4 in the same method as that in Example 1.
[0094] In addition, any of a lower layer and an upper layer shown in Table 12 was formed on the present invention coated tools 13 to 19 under the forming conditions shown in Table 3.
[0095] In addition, for the purpose of comparison, like the present invention coated tools, comparative coated tools 11 to 19 shown in Table 14 were produced by depositing hard coating layers on the surfaces of the same tool bodies α to γ and the tool body δ to have target layer thicknesses shown in
[0096] In addition, like the present invention coated tools 13 to 19, any of a lower layer and an upper layer shown in Table 12 was formed on the comparative coated tools 13 to 19 under the forming conditions shown in Table 3.
[0097] For reference, a reference coated tool 20 shown in Table 14 was produced by depositing (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layers of the reference example on the surfaces of the tool body β to have target layer thicknesses through arc ion plating using a physical vapor deposition apparatus in the related art.
[0098] The same conditions as those described in Example 1 were used as the conditions of the arc ion plating.
[0099] The section of each of constituent layers of the present invention coated tools 11 to 19, the comparative coated tools 11 to 19, and the reference coated tool 20 was measured using a scanning electron microscope (at a magnification of 5000×). An average layer thickness was obtained by measuring and averaging the layer thicknesses of five points in an observation visual field. All of the results showed substantially the same average layer thicknesses as the target layer thicknesses shown in Tables 12 to 14.
[0100] Regarding the hard coating layers of the present invention coated tools 11 to 19, the comparative coated tools 11 to 19, and the reference coated tool 20, using the same method as that described in Example 1, the average amount Xavg of Al, the average amount Yavg of C, the average grain width W and the average aspect ratio A of crystal grains having a cubic structure included in the (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layer of a columnar structure were calculated. In addition, using the same method as that described in Example 1, inclined angles of normal lines of {111} planes which were crystal planes of the crystal grains having an NaCl type face-centered cubic structure with respect to the normal line (the direction perpendicular to the surface of the body in the section polished surface) of the surface of the body were measured. On the basis of the measurement results, measured inclined angles in a range of 0 degrees to 45 degrees among the measured inclined angles were divided into intervals of 0.25 degrees, frequencies in the respective divisions were aggregated, and the presence of the peaks of the frequencies present in a range of 0 degrees to 10 degrees was checked. In addition, the proportion of the frequencies present in the range of 0 degrees to 10 degrees was obtained.
[0101] Moreover, the average grain size R of fine crystal grains that were present in the grain boundaries of the columnar structure constituted by the individual crystal grains having an NaCl type face-centered cubic structure and the area proportion of the fine crystal grains were calculated using the same method as that described in Example 1.
[0102] The results are shown in Tables 13 and 14.
[0103] Regarding a layer of a complex nitride or complex carbonitride of Ti and Al included in the hard coating layers of the present invention coated tools 11 to 19, a plurality of visual fields were observed using a scanning electron microscope (at a magnification of 5000× and 20,000×). As illustrated in the film configuration schematic view in
[0104] In addition, regarding the layer of a complex nitride or complex carbonitride, the columnar structure constituted by the individual crystal grains having a cubic structure were analyzed in the longitudinal sectional direction of the layer of a complex nitride or complex carbonitride of Ti and Al using an electron backscatter diffraction apparatus, and it was confirmed that the fine crystal grains present in the grain boundaries had a hexagonal structure.
TABLE-US-00010 TABLE 10 Mixing composition (mass %) Type Co TiC ZrC TaC NbC Cr.sub.3C.sub.2 TiN WC Tool α 6.5 — 1.5 — 2.9 0.1 1.5 Remainder body β 7.6 2.6 — 4.0 0.5 — 1.1 Remainder γ 6.0 — — — — — — Remainder
TABLE-US-00011 TABLE 11 Mixing composition (mass %) Type Co Ni NbC WC TiCN Tool δ 11 4 6 15 Remainder body
TABLE-US-00012 TABLE 12 Hard coating layer (numerical value at the bottom indicates target average layer thickness (μm)) Tool Lower layer Upper layer body First Second First Second Type symbol layer layer layer layer Present 11 α — — — — invention 12 δ — — — — coated tool, 13 β TiN — — — comparative (0.3) coated tool, 14 γ TiN — — — reference (0.3) coated tool 15 α TiN — — — (0.3) 16 δ TiN — Al.sub.2O.sub.3 — (0.3) (2.5) 17 β TiN — TiCNO Al.sub.2O.sub.3 (0.3) (0.3) (3.5) 18 γ TiC — — (0.5) 19 α TiN TiCN — — (0.3) (5)
TABLE-US-00013 TABLE 13 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) Division of Proportion of Formation Difference Dx inclined angles frequencies of 0 Average symbol of between average in which highest degrees to 10 de- grain TiAlCN of maximum values peak is present grees in inclined width W Tool film forming Average Average of x and an in inclined angle angle division in of cubic body process amount amount average of frequency distri- inclined angle fre- grains Type symbol (see Table 4) Xavg of Al Yavg of C minimum values bution (degrees) quency distribution (%) (mm) Present 11 α A 0.90 0.0001 or less 0.14 1.25-1.5 46 0.35 invention 12 δ B 0.68 0.003 0.19 5.25-5.5 48 0.12 coated 13 β C 0.85 0.0001 or less 0.13 1.25-1.5 72 2.2 tool 14 γ D 0.86 0.0001 or less 0.09 2.25-2.5 68 1.8 15 α E 0.79 0.0012 0.06 1.75-2.0 78 1.6 16 δ F 0.71 0.0001 or less 0.13 3.25-3.5 72 0.8 17 β G 0.83 0.0001 or less 0.11 3.75-4.0 66 1.1 18 γ H 0.77 0.0001 or less 0.05 7.25-7.5 83 1.6 19 α I 0.84 0.0001 or less 0.09 8.25-8.5 71 1.8 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) Average value Compositional vari- Lattice Area Average of periods of ation XO in amount constant proportion grain size Average compositional of Al in plane of grains of R of aspect change in Ti orthogonal to peri- having NaCl hexagonal hexagonal Target ratio A and Al along odic compositional type face- fine grains fine layer of cubic <001> orientation change along <001> centered cubic (% by grains thickness Type grains (nm) orientation structure (Å) area) (mm) (mm) Present 11 3.6 16 0.015 4.065 0 — 3.5 invention 12 2.3 33 0.01 or less 4.108 0 — 2.5 coated 13 3.8 48 0.01 or less 4.075 0 — 10.0 tool 14 5 23 0.01 or less 4.073 0 — 7.0 15 7 85 0.01 or less 4.086 18 0.15 20.0 16 3.5 12 0.01 or less 4.102 0 — 10.0 17 6.5 65 0.01 or less 4.078 0 — 6.0 18 7 33 0.01 or less 4.090 25 0.11 9.0 19 1.8 78 0.01 or less 4.076 0 — 5.0
TABLE-US-00014 TABLE 14 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) Division of Proportion of Formation inclined angles frequencies of 0 Average symbol of in which highest degrees to 10 de- grain Average TiAlCN peak is present grees in inclined width W aspect Tool film forming Average Average in inclined angle angle division in of cubic ratio A body process amount amount frequency distri- inclined angle fre- grains of cubic Type symbol (see Table 5) Xavg of Al Yavg of C bution (degrees) quency distribution (%) (mm) grains Comparative 11 a A′ 0.91 0.0001 or less 11.5 to 11.75 25.0 2.1 2.5 coated tool 12 d B′ 0.83 0.0001 or less 34.25 to 34.5 31.0 1.3 4.5 13 b C′ 0.67 0.011 41.25 to 41.5 19.0 1.5 1.6 14 g D′ 0.73 0.0001 or less 27.5 to 27.75 22.0 0.8 5.5 15 a E′ 0.96 0.0001 or less 31.25 to 31.5 23.0 2.4 3 16 d F′ 0.88 0.005 36.25 to 36.5 31.0 1.5 1.5 17 b G′ 0.62 0.0001 or less 23.5 to 23.75 18.0 1.2 3.2 18 g H′ 0.78 0.0001 or less 17.5 to 17.75 26.0 1.3 4.4 19 a I′ 0.8 0.003 39.25 to 39.5 22.5 1.6 2.3 Reference 20 b AIP 0.48 — — — 1.2 3.5 coated tool Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) Average value Compositional vari- Lattice Area Average Difference Dx of periods of ation XO in amount constant proportion grain size between average compositional of Al in plane of grains of R of of maximum values change in Ti orthogonal to peri- having NaCl hexagonal hexagonal Target of x and an and Al along odic compositional type face- fine grains fine layer average of <001> orientation change along <001> centered cubic (% by grains thickness Type minimum values (nm) orientation structure (Å) area) (mm) (mm) Comparative 11 — — — 4.063 28 0.23 3.5 coated tool 12 — — — 4.078 5 0.06 2.5 13 — — — 4.110 15 0.21 10.0 14 — — — 4.098 7 0.25 7.0 15 — — — 4.053 13 0.18 20.0 16 — — — 4.069 25 0.34 10.0 17 — — — 4.120 12 0.15 6.0 18 — — — 4.088 34 0.26 9.0 19 — — — 4.084 16 0.18 5.0 Reference 20 — — — 4.147 — — 3.5 coated tool (Note) “AIP” indicates film formation through arc ion plating.
[0105] Next, in a state in which each of the various coated tools was screwed to a tip end portion of an insert holder made of tool steel by a fixing tool, the present invention coated tools 11 to 19, the comparative coated tools 11 to 19, and the reference coated tool 20 were subjected to a dry high-speed intermittent cutting test for carbon steel and a wet high-speed intermittent cutting test for cast iron, which are described below, and the flank wear width of a cutting edge was measured.
[0106] Cutting conditions 1:
[0107] Work material: a round bar with four longitudinal grooves formed at equal intervals in the longitudinal direction of JIS SCM435
[0108] Cutting speed: 380 m/min
[0109] Depth of cut: 1.5 mm
[0110] Feed rate: 0.2 mm/rev
[0111] Cutting time: 5 minutes
[0112] (a typical cutting speed is 220 m/min)
[0113] Cutting conditions 2:
[0114] Work material: a round bar with four longitudinal grooves formed at equal intervals in the longitudinal direction of JIS FCD700
[0115] Cutting speed: 320 m/min
[0116] Depth of cut: 1.0 mm
[0117] Feed rate: 0.2 mm/rev
[0118] Cutting time: 5 minutes
[0119] (a typical cutting speed is 180 m/min)
[0120] The results of the cutting test are shown in Table 15.
TABLE-US-00015 TABLE 15 Flank wear width Cutting test result (mm) (min) Cutting Cutting Cutting Cutting conditions conditions conditions conditions Type 1 2 Type 1 2 Present 11 0.26 0.28 Comparative 11 2.3* 3.5* invention 12 0.25 0.31 coated tool 12 3.6* 3.2* coated 13 0.19 0.21 13 2.1* 3.6* tool 14 0.12 0.13 14 4.2* 3.3* 15 0.15 0.17 15 4.8* 2.1* 16 0.18 0.16 16 3.6* 2.3* 17 0.11 0.14 17 1.8* 2.5* 18 0.22 0.24 18 1.9* 2.8* 19 0.23 0.21 19 2.3* 2.1* Reference 20 1.2* 1.5* coated tool Mark * in boxes of comparative coated tools and reference coated tools indicates a cutting time (min) until the end of a service life caused by the occurrence of chipping.
EXAMPLE 3
[0121] As raw material powders, a cBN powder, a TiN powder, a TiC powder, an Al powder, and an Al.sub.2O.sub.3 powder, all of which had an average grain size of 0.5 μm to 4 μm, were prepared, and the raw material powders were mixed in mixing compositions shown in Table 16. The mixture was wet-blended by a ball mill for 80 hours and was dried. Thereafter, the resultant was press-formed into compacts having dimensions with a diameter of 50 mm and a thickness of 1.5 mm at a pressure of 120 MPa, and the compacts were then sintered in a vacuum at a pressure of 1 Pa under the condition that the compacts were held at a predetermined temperature in a range of 900° C. to 1300° C. for 60 minutes, thereby producing cutting edge preliminary sintered bodies. In a state in which the preliminary sintered body was superimposed on a support piece made of WC-based cemented carbide, which was additionally prepared to contain Co: 8 mass % and WC: the remainder and have dimensions with a diameter of 50 mm and a thickness of 2 mm, the resultant was loaded in a typical ultrahigh-pressure sintering apparatus, and was subjected to ultrahigh-pressure sintering under typical conditions including a pressure of 4 GPa, a predetermined temperature in a range of 1200° C. to 1400° C., and a holding time of 0.8 hours. After the sintering, upper and lower surfaces were polished using a diamond grinding wheel, and were split into predetermined dimensions by a wire electric discharge machining apparatus. Furthermore, the resultant was brazed to a brazing portion (corner portion) of an insert body made of WC-based cemented carbide having a composition including Co: 5 mass %, TaC: 5 mass %, and WC: the remainder and a shape (a 80° rhombic shape with a thickness of 4.76 mm and an inscribed circle diameter of 12.7 mm) according to ISO standard CNGA120412 using a brazing filler metal made of a Ti—Zr—Cu alloy having a composition including Zr: 37.5%, Cu: 25%, and Ti: the remainder in terms of mass %, and the outer circumference thereof was machined into predetermined dimensions. Thereafter, a cutting edge portion was subjected to honing to have a width of 0.13 mm and an angle of 25°, and the resultant was further subjected to finish polishing, thereby producing each of tool bodies a and b with an insert shape according to ISO standard CNGA120412.
TABLE-US-00016 TABLE 16 Mixing composition (mass %) Type TiN TiC Al Al.sub.2O.sub.3 cBN Tool a 50 — 5 3 Remainder body b — 50 4 3 Remainder
[0122] Subsequently, present invention coated tools 21 to shown in Table 18 were produced by depositing hard coating layers including at least a (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layer on the surfaces of the tool bodies a and b to have target layer thicknesses using a typical chemical vapor deposition apparatus under the conditions shown in Tables 3 and 4 in the same method as that in Example 1.
[0123] In addition, any of a lower layer and an upper layer shown in Table 17 was formed on the present invention coated tools 22 to 24 under the forming conditions shown in Table 3.
[0124] In addition, for the purpose of comparison, comparative coated tools 21 to 24 shown in Table 19 were produced by depositing hard coating layers including at least a (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layer on the surfaces of the same tool bodies a and b to have target layer thicknesses under the conditions shown in Tables 3 and 5 using a typical chemical vapor deposition apparatus.
[0125] In addition, like the present invention coated tools 22 to 24, any of a lower layer and an upper layer shown in Table 17 was formed on the comparative coated tools 22 to 24 under the forming conditions shown in Table 3.
[0126] For reference, a reference coated tool 25 shown in Table 19 was produced by depositing (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layers on the surfaces of the tool bodies a and b to have target layer thicknesses through arc ion plating using a physical vapor deposition apparatus in the related art.
[0127] The same conditions as those described in Example 1 were used as the conditions of the arc ion plating, and the reference coated tool 25 was produced by depositing (Al,Ti)N layers having a target composition and a target layer thickness shown in Table 19 on the surfaces of the tool bodies.
[0128] The section of each of constituent layers of the present invention coated tools 21 to 24, the comparative coated tools 21 to 24, and the reference coated tool 25 was measured using a scanning electron microscope (at a magnification of 5000×). An average layer thickness was obtained by measuring and averaging the layer thicknesses of five points in an observation visual field. All of the results showed substantially the same average layer thicknesses as the target layer thicknesses shown in Tables 17 to 19.
[0129] Regarding the hard coating layers of the present invention coated tools 21 to 24, the comparative coated tools 21 to 24, and the reference coated tool 25, using the same method as that described in Example 1, the average amount Xavg of Al, the average amount Yavg of C, the average grain width W and the average aspect ratio A of crystal grains having an NaCl type face-centered cubic structure included in the (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layer were calculated. In addition, using the same method as that described in Example 1, inclined angles of normal lines of {111} planes which were crystal planes of the crystal grains having an NaCl type face-centered cubic structure with respect to the normal line (the direction perpendicular to the surface of the body in the section polished surface) of the surface of the body were measured. On the basis of the measurement results, measured inclined angles in a range of 0 degrees to 45 degrees among the measured inclined angles were divided into intervals of 0.25 degrees, frequencies in the respective divisions were aggregated, and the presence of the peaks of the frequencies present in a range of 0 degrees to 10 degrees was checked. In addition, the proportion of the frequencies present in the range of 0 degrees to 10 degrees was obtained.
[0130] Moreover, the average grain size R of fine crystal grains that were present in the grain boundaries of the columnar structure constituted by the individual crystal grains having an NaCl type face-centered cubic structure and the area proportion of the fine crystal grains were calculated using the same method as that described in Example 1. The results are shown in Tables 18 and 19.
TABLE-US-00017 TABLE 17 Hard coating layer (numerical value at the bottom indicates target average layer thickness (μm)) Tool body Lower layer Type symbol First layer Upper layer Present invention 21 a — — coated tool, com- 22 b TiN (0.3) — parative coated 23 a TiN (0.3) — tool, reference 24 b TiN (0.3) TiN (0.3) coated tool
TABLE-US-00018 TABLE 18 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) Division of Proportion of Formation Difference Dx inclined angles frequencies of 0 Average symbol of between average in which highest degrees to 10 de- grain TiAlCN of maximum values peak is present grees in inclined width W Tool film forming Average Average of x and an in inclined angle angle division in of cubic body process amount amount average of frequency distri- inclined angle fre- grains Type symbol (see Table 4) Xavg of Al Yavg of C minimum values bution (degrees) quency distribution (%) (mm) Present 21 a A 0.91 0.0001 or less 0.15 5.25 to 5.5 55 0.4 invention 22 b B 0.66 0.002 0.18 7.5 to 7.75 48 0.2 coated 23 a C 0.85 0.0001 or less 0.09 1.25 to 1.5 61 0.9 tool 24 b D 0.81 0.0001 or less 0.11 2.25 to 2.5 53 0.8 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) Average value Compositional vari- Lattice Area Average of periods of ation XO in amount constant proportion grain size Average compositional of Al in plane of grains of R of aspect change in Ti orthogonal to peri- having NaCl hexagonal hexagonal Target ratio A and Al along odic compositional type face- fine grains fine layer of cubic <001> orientation change along <001> centered cubic (% by grains thickness Type grains (nm) orientation structure (Å) area) (mm) (mm) Present 21 3 18 0.015 4.063 0 — 3.5 invention 22 5 28 0.01 or less 4.112 0 — 1.2 coated 23 2.1 43 0.01 or less 4.075 0 — 2.0 tool 24 2.8 26 0.01 or less 4.082 0 — 2.5
TABLE-US-00019 TABLE 19 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) Division of Proportion of Formation inclined angles frequencies of 0 Average symbol of in which highest degrees to 10 de- grain Average TiAlCN peak is present grees in inclined width W aspect Tool film forming Average Average in inclined angle angle division in of cubic ratio A body process amount amount frequency distri- inclined angle fre- grains of cubic Type symbol (see Table 5) Xavg of Al Yavg of C bution (degrees) quency distribution (%) (mm) grains Comparative 21 a A′ 0.93 0.0001 or less 15.5 to 15.75 29.0 0.8 2.2 coated tool 22 b B′ 0.85 0.0001 or less 22.25 to 22.5 19.0 0.6 2.5 23 a C′ 0.63 0.009 38.25 to 38.5 23.0 0.7 1.3 24 b D′ 0.71 0.0001 or less 16 to 16.25 27.0 0.9 2.4 Reference 25 b AIP 0.48 — — — 1.2 3.5 coated tool Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) Average value Compositional vari- Lattice Area Average Difference Dx of periods of ation XO in amount constant proportion grain size between average compositional of Al in plane of grains of R of of maximum values change in Ti orthogonal to peri- having NaCl hexagonal hexagonal Target of x and an and Al along odic compositional type face- fine fine layer average of <001> orientation change along <001> centered cubic grains (% grains thickness Type minimum values (nm) orientation structure (Å) by area) (mm) (mm) Comparative 21 — — — 4.059 23 0.25 3.5 coated tool 22 — — — 4.075 3 0.12 1.2 23 — — — 4.118 16 0.18 2.0 24 — — — 4.102 5 0.26 2.5 Reference 25 — — — 4.147 — — 2.5 coated tool
[0131] Next, in a state in which each of the various coated tools was screwed to a tip end portion of an insert holder made of tool steel by a fixing tool, the present invention coated tools 21 to 24, the comparative coated tools 21 to 24, and the reference coated tool 25 were subjected to a dry high-speed intermittent cutting test for carburized alloy steel, which is described below, and the flank wear width of a cutting edge was measured.
[0132] Tool body: cubic boron nitride-based ultrahigh-pressure sintered body
[0133] Cutting test: dry high-speed intermittent cutting test for carburized alloy steel
[0134] Work material: a round bar with four longitudinal grooves formed at equal intervals in the longitudinal direction of JIS SCr420 (hardness HRC62)
[0135] Cutting speed: 240 m/min
[0136] Depth of cut: 0.12 mm
[0137] Feed rate: 0.1 mm/rev
[0138] Cutting time: 4 minutes
[0139] The results of the cutting test are shown in Table 20.
TABLE-US-00020 TABLE 20 Flank wear Cutting test Type width (mm) Type results (min) Present 21 0.18 Comparative 21 1.5* invention 22 0.16 coated tool 22 1.2* coated tool 23 0.12 23 2.2* 24 0.15 24 2.8* Reference 25 1.3* coated tool Mark * in boxes of comparative coated tools and reference coated tools indicates a cutting time (min) until the end of a service life caused by the occurrence of chipping.
[0140] From the results shown in Tables 9, 15, and 20, it is apparent that in the coated tool of the present invention, in the crystal grains having an NaCl type face-centered cubic structure included in the layer of a complex nitride or complex carbonitride of Ti and Al included in the hard coating layer, a periodic compositional variation in Ti and Al is present in the crystal grains, and thus strain is introduced into crystal grains, resulting in an improvement in hardness. In addition, since the columnar structure is included, high wear resistance is exhibited. At the same time, since the fine crystal grains having a hexagonal structure are present in the grain boundaries of the columnar structure, grain boundary sliding is suppressed, resulting in an improvement in toughness. Furthermore, since the crystal grains having an NaCl type face-centered cubic structure are aligned with {111} planes, both flank wear resistance and crater wear resistance are improved. As a result, the coated tool of the present invention exhibits excellent wear resistance as well as excellent chipping resistance and defect resistance during long-term use even in a case of being used for high-speed intermittent cutting work during which intermittent and impact loads are exerted on a cutting edge.
[0141] Contrary to this, it is apparent that the comparative coated tools 1 to 9, 11 to 19, 21 to 24, and the reference coated tools 10, 20, and 25 generates high-temperature heat and generates chipping, defects, and the like in a case of being used for high-speed intermittent cutting work during which intermittent and impact loads are exerted on a cutting edge, resulting in the end of the service life within a short period of time.
INDUSTRIAL APPLICABILITY
[0142] As described above, the coated tool of the present invention can be used as a coated tool for various work materials as well as for high-speed intermittent cutting work of alloy steel and further exhibits excellent chipping resistance and wear resistance during long-term use, thereby sufficiently satisfying an improvement in performance of a cutting device, power saving and energy saving during cutting work, and a further reduction in costs.