SURFACE-COATED CUTTING TOOL IN WHICH HARD COATING LAYER EXHIBITS EXCELLENT CHIPPING RESISTANCE
20180154463 ยท 2018-06-07
Assignee
Inventors
- Kousuke YANAGISAWA (Naka-shi, JP)
- Sho TATSUOKA (Naka-shi, JP)
- Kenichi SATO (Naka-shi, JP)
- Kenji YAMAGUCHI (Naka-shi, JP)
Cpc classification
B23C5/16
PERFORMING OPERATIONS; TRANSPORTING
C23C16/45523
CHEMISTRY; METALLURGY
C23C28/044
CHEMISTRY; METALLURGY
B23C2224/22
PERFORMING OPERATIONS; TRANSPORTING
C23C28/048
CHEMISTRY; METALLURGY
International classification
Abstract
A coated tool has a hard coating layer including a layer of a complex nitride or complex carbonitride expressed by (Ti.sub.1-xAl.sub.x)(C.sub.yN.sub.1-y). A periodic concentration variation is present in crystal grains of a complex nitride or complex carbonitride having a NaCl type face-centered cubic structure in the layer. The periodic concentration variation direction includes a direction at 30 degrees or less with respect to a surface of a tool body. An area percentage of a periodic concentration variation of Ti and Al is 40% or more. The concentration variation period is 1 to 10 nm. A difference between an average of local maximums and an average of local minimums of a periodically varying amount x of Al is 0.01 to 0.1. Fine crystal grains having a hexagonal structure with an average grain size of 0.01 to 0.3 m are present at grain boundaries in 5% or less of the area.
Claims
1. A surface-coated cutting tool comprising: a tool body, wherein a hard coating layer is provided on a surface of the tool body made of any of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or a cubic boron nitride-based ultrahigh-pressure sintered body, (a) the hard coating layer includes at least a layer of a complex nitride or complex carbonitride of Ti and Al with an average layer thickness of 1 to 20 m, (b) the layer of a complex nitride or complex carbonitride includes at least crystal grains of a complex nitride or complex carbonitride having a NaCl type face-centered cubic structure, and (c) at least the crystal grains having a NaCl type face-centered cubic structure in which, in a case where the layer of a complex nitride or complex carbonitride is analyzed in an arbitrary section perpendicular to the surface of the tool body, a periodic concentration variation of Ti and Al is present in the crystal grains having a NaCl type face-centered cubic structure, and when a direction in which a period of a concentration variation in the periodic concentration variation of Ti and Al is minimized is obtained, an angle between the direction in which the period of the concentration variation is minimized and the surface of the tool body is 30 degrees or less, are present.
2. The surface-coated cutting tool according to claim 1, wherein in a case where a composition of the layer of a complex nitride or complex carbonitride is expressed by a composition formula: (Ti.sub.1-xAl.sub.x)(C.sub.yN.sub.1-y), an average amount X.sub.avg of Al in a total amount of Ti and Al and an average amount Y.sub.avg of C in a total amount of C and N (here, each of X.sub.avg and Y.sub.avg is in atomic ratio) respectively satisfy 0.40X.sub.avg0.95 and 0Y.sub.avg0.005.
3. The surface-coated cutting tool according to claim 1, wherein a ratio of the crystal grains having a NaCl type face-centered cubic structure in which, when the layer of a complex nitride or complex carbonitride is observed in the section, the periodic concentration variation of Ti and Al is present, and the angle between the direction in which the period of the concentration variation in the periodic concentration variation of Ti and Al is minimized and the surface of the tool body is 30 degrees or less, to an area of the layer of a complex nitride or complex carbonitride is 40% by area or more.
4. The surface-coated cutting tool according to claim 1, wherein in the crystal grains having a NaCl type face-centered cubic structure in which the periodic concentration variation of Ti and Al is present in the layer of a complex nitride or complex carbonitride and the angle between the direction in which the period of the concentration variation in the periodic concentration variation of Ti and Al is minimized and the surface of the tool body is 30 degrees or less, the period of the periodic concentration variation of Ti and Al is 1 to 10 nm, and a difference between an average of local maximums and an average of local minimums of a periodically varying amount x of Al is 0.01 to 0.1.
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 a sectional direction, at grain boundaries between the individual crystal grains having a 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 ratio of the fine crystal grains present is 5% by area or less, and an average grain size R of the fine crystal grains is 0.01 to 0.3 m.
6. The surface-coated cutting tool according to claim 1, wherein between the tool body and the layer of a complex nitride or complex carbonitride of Ti and Al, a lower layer which is formed of a Ti compound layer including 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 to 20 m is present.
7. The surface-coated cutting tool according to claim 1, wherein an upper layer which includes at least an aluminum oxide layer and has an average total layer thickness of 1 to 25 m is formed in an upper portion of the layer of a complex nitride or complex carbonitride.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0072] 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 drawing(s), wherein like designations denote like elements in the various views, and wherein:
[0073]
[0074]
[0075]
[0076]
DETAILED DESCRIPTION OF THE INVENTION
[0077] Next, examples of a coated tool of the present invention will be described in more detail.
Example 1
[0078] As raw material powders, a WC powder, a TiC powder, a TaC powder, a NbC powder, a Cr.sub.3C.sub.2 powder, and a Co powder, all of which had an average grain size of 1 to 3 m, 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 green compacts having predetermined shapes at a pressure of 98 MPa, and the green compacts were sintered in a vacuum at 5 Pa under the condition that the green 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.
[0079] 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, a NbC powder, a WC powder, a Co powder, and a Ni powder, all of which had an average grain size of 0.5 to 2 m, 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 a green compact at a pressure of 98 MPa, and the green compact was sintered in a nitrogen atmosphere at 1.3 kPa under the condition that the green compact was 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.
[0080] Next, present invention coated tools 1 to 10 shown in Table 7 were produced by forming, on the surfaces of the tool bodies A to D, an initial film formation layer under forming conditions A to J shown in Tables 4 and 5, that is, under first stage film formation conditions and then forming a film under second stage film formation conditions, using a chemical vapor deposition apparatus.
[0081] That is, the present invention coated tools 1 to 10 were produced by forming a (Ti.sub.1-xAl.sub.x)(C.sub.yN.sub.1-y) layer shown in Table 7 through a thermal CVD method for a predetermined time according to the forming conditions A to J shown in Tables 4 and 5, in which a gas group A of NH.sub.3 and H.sub.2 and a gas group B of TiCl.sub.4, AlCl.sub.3, N.sub.2, and H.sub.2 were used, 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 2.5% and H.sub.2: 60% to 75% and a gas group B of AlCl.sub.3: 0.10% to 0.90%, TiCl.sub.4: 0.10% to 0.30%, N.sub.2: 0.0% to 12.0%, C.sub.2H.sub.4: 0% to 0.5%, 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 800 C., a supply period was 1 to 2 seconds, a gas supply time per one period was 0.05 to 0.12 seconds, and a phase difference between the supply of the gas group A and the supply of the gas group B was 0.04 to 0.09 seconds.
[0082] In addition, in the present invention, the lower the film formation temperature of the layer of a complex nitride or complex carbonitride, the lower the ratio of pores in the initial film formation layer. Therefore, the hardness is increased, or the adhesion strength between the layer of a complex nitride or complex carbonitride and the lower layer is increased, resulting in an improvement in peeling resistance. On the other hand, the higher the film formation temperature at which the layer of a complex nitride or complex carbonitride is formed, the higher the crystallinity. Therefore, an effect of improving the wear resistance is achieved. Accordingly, in the present invention, the film formation is performed in two separate stages, and the first stage film formation is performed at a lower temperature than in the second stage film formation, resulting in the improvement in the peeling resistance and wear resistance.
[0083] In addition, a lower layer and an upper layer shown in Table 6 were formed on each of the present invention coated tools 1 to 10 under forming conditions shown in Table 3.
[0084] In addition, for the purpose of comparison, comparative coated tools 1 to 10 were produced by depositing hard coating layers including at least a layer of a complex nitride or complex carbonitride of Ti and Al on the surfaces of the tool bodies A to D as in the present invention coated tools 1 to 10 to have target layer thicknesses (m) shown in
[0085] In addition, like the present invention coated tools 1 to 10, a lower layer and an upper layer shown in Table 6 were formed on the comparative coated tools 1 to 10 under the forming conditions shown in Table 3.
[0086] The section of each of constituent layers of the present invention coated tools 1 to 10 and the comparative coated tools 1 to 10 in the direction perpendicular to the tool body was measured using a scanning electron microscope (at a magnification of 5,000). 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 7 and 8.
[0087] In addition, regarding the average amount X.sub.avg of Al of the layer of a complex nitride or complex carbonitride, a sample, of which the surface was polished, was irradiated with electron beams from the sample surface side, and the average amount X.sub.avg of Al was obtained by averaging 10 points of the analytic result of obtained characteristic X-rays, using an electron probe micro-analyzer (EPMA). The average amount Y.sub.avg of C was obtained by secondary ion mass spectroscopy (SIMS). Ion beams were emitted toward a range of 70 m70 m from the sample surface side, and the concentration of components emitted by a sputtering action was measured in a depth direction. The average amount Y.sub.avg of C represents the average value of the layer of a complex nitride or complex carbonitride of Ti and Al in the depth direction. However, the amount of C excludes an unavoidable amount of C, which was included even though gas containing C was 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 C.sub.2H.sub.4 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 C.sub.2H.sub.4 was intentionally supplied was obtained as Y.sub.avg.
[0088] In addition, a small area of the layer of a complex nitride or complex carbonitride was observed by using the transmission electron microscope under the condition of an acceleration voltage of 200 kV, and area analysis from the section side was performed using energy-dispersive X-ray spectroscopy (EDS), whereby the presence or absence of a periodic concentration variation of Ti and Al in the composition formula: (Ti.sub.1-xAl.sub.x)(C.sub.yN.sub.1-y) in the crystal grains having the cubic structure was checked, and the area ratio of the crystal grains having the direction of the concentration variation of the present invention was obtained.
[0089] The results are shown in Tables 7 and 8. Furthermore, the angle of the plane parallel to the surface of the tool body with respect to the direction of the periodic concentration variation was measured as follows.
[0090] The angle could be obtained by observing an arbitrary area of 1 m1 m from an arbitrary section perpendicular to the body in the crystal grains having a NaCl type face-centered cubic structure using the transmission electron microscope and measuring the angle between the direction in which the periodic concentration variation of Ti and Al is present and the period of the periodic concentration variation of Ti and Al in the section is minimized and the surface of the tool body. In addition, the minimum angle of the measured angle between the direction in which the period of the periodic concentration variation is minimized and the surface of the tool body was determined as the direction (degrees) of the periodic concentration variation, and it was determined whether or not the direction of the periodic concentration variation was 30 degrees or less. A case where the direction of the periodic concentration variation was 30 degrees or less is indicated as present and a case where the direction was more than 30 degrees is indicated as absent in Tables 7 and 8.
[0091] In addition, regarding the crystal grains having the cubic structure in which the periodic concentration variation was present, the period of the concentration variation of Ti and Al was obtained through the observation of the small area using the transmission electron microscope and the line analysis from the section side using energy-dispersive X-ray spectroscopy (EDS).
[0092] As a method of measuring the period, regarding the crystal grains, magnification was set based on the results of the plane analysis such that the concentration variation of about ten periods from the contrasting density of the composition was within the measurement range, the measurement of the period according to the line analysis through EDS along the direction of the periodic concentration variation of the surface of the tool body was performed on a range of at least five periods, and the average value thereof was obtained as the period of the periodic concentration variation of Ti and Al.
[0093] Furthermore, the difference x between the average of local maximums and the average of local minimums of the amount x of Al in the periodic concentration variation was obtained.
[0094] A specific measurement method is as follows.
[0095] Regarding the crystal grains, magnification was set based on the results of the area analysis such that the concentration variation of about ten periods from the contrasting density of the composition was within the measurement range, the line analysis through EDS along the direction of the periodic concentration variation of the surface of the tool body was performed on the range of at least five periods, and the difference between the average values of local maximums and local minimums of the periodic concentration variation of Ti and Al was obtained as x.
[0096] Regarding the crystal grain from which the minimum measurement value of the measured angle between the direction in which the period of the periodic concentration variation is minimized and the surface of the tool body was obtained, the period and x thereof are shown in Tables 7 and 8.
[0097] In addition, regarding the layer of a complex nitride or complex carbonitride, a plurality of visual fields were observed using the transmission electron microscope, and the area ratio of the fine crystal grains having a hexagonal structure present at the grain boundaries between the crystal grains having a NaCl type face-centered cubic structure and the average grain size R of the fine crystal grains having a hexagonal structure were measured.
[0098] Identification of fine hexagonal crystals present at grain boundaries was performed by analyzing an electron beam diffraction pattern using the transmission electron microscope. The average grain size of the fine hexagonal crystals was obtained by measuring the grain size of the grains present in the measurement range of 1 m1 m including grain boundaries, and the area ratio thereof was obtained from a value obtained by calculating the total area of the fine hexagonal crystals. Furthermore, regarding the grain size, circumscribed circles were created for grains identified as hexagonal crystals, the radii of the circumscribed circles were measured, and the average value was determined as the grain size.
[0099] The obtained results are 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 body A 8.0 1.5 3.0 0.4 Remainder 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 M.sub.2C WC TiCN Tool body D 8 5 1 6 6 10 Remainder
TABLE-US-00003 TABLE 3 Forming conditions (pressure of reaction atmosphere Constituent layers of hard is expressed as kPa and temperature is expressed coating layer as C.) Type Formation Reaction gas composition (% by TiAlCN symbol volume) Reaction atmosphere layer TiAlCN TiAlCN See Table 4 Pressure Temperature Ti TiC TiC TiCl.sub.4: 4.2%, CH.sub.4: 8.5%, H.sub.2: 7 800 compound remainder layer TiN TiN TiCl.sub.4: 4.2%, N.sub.2: 35%, H.sub.2: 7 800 remainder l-TiCN l-TiCN TiCl.sub.4: 2.0%, CH.sub.3CN: 1.5%, N.sub.2: 7 800 8%, H.sub.2: remainder TiCNO TiCNO TiCl.sub.4: 2%, CH.sub.3CN: 0.6%, CO: 1%, 7 800 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: 2.2%, CO.sub.2: 5.5%, HC1: 7 800 layer 2.2%, H.sub.2S: 0.2%, H.sub.2: remainder
TABLE-US-00004 TABLE 4 Gas conditions (reaction gas composition indicates proportion Formation of TiAlCN layer in total amount of gas group A and gas group B) Formation Reaction gas group A Process type symbol composition (% by volume) Reaction gas group B composition (% by volume) Present invention A NH.sub.3: 2.5%, H.sub.2: 67% TiCl.sub.4: 0.10%, AlCl.sub.3: 0.90%, N.sub.2: 0%, C.sub.2H.sub.4: 0%, H.sub.2 as remainder film forming B NH.sub.3: 2.1%, H.sub.2: 68% TiCl.sub.4: 0.10%, AlCl.sub.3: 0.30%, N.sub.2: 0%, C.sub.2H.sub.4: 0%, H.sub.2 as remainder process C NH.sub.3: 1.9%, H.sub.2: 68% TiCl.sub.4: 0.15%, AlCl.sub.3: 0.25%, N.sub.2: 0%, C.sub.2H.sub.4: 0%, H.sub.2 as remainder D NH.sub.3: 1.5%, H.sub.2: 69% TiCl.sub.4: 0.20%, AlCl.sub.3: 0.15%, N.sub.2: 0%, C.sub.2H.sub.4: 0%, H.sub.2 as remainder E NH.sub.3: 2.2%, H.sub.2: 62% TiCl.sub.4: 0.10%, AlCl.sub.3: 0.10%, N.sub.2: 12%, C.sub.2H.sub.4: 0%, H.sub.2 as remainder F NH.sub.3: 2.0%, H.sub.2: 73% TiCl.sub.4: 0.15%, AlCl.sub.3: 0.10%, N.sub.2: 7%, C.sub.2H.sub.4: 0%, H.sub.2 as remainder G NH.sub.3: 2.2%, H.sub.2: 60% TiCl.sub.4: 0.18%, AlCl.sub.3: 0.10%, N.sub.2: 5%, C.sub.2H.sub.4: 0%, H.sub.2 as remainder H NH.sub.3: 2.1%, H.sub.2: 60% TiCl.sub.4: 0.30%, AlCl.sub.3: 0.10%, N.sub.2: 0%, C.sub.2H.sub.4: 0.5%, H.sub.2 as remainder I NH.sub.3: 1.6%, H.sub.2: 70% TiCl.sub.4: 0.15%, AlCl.sub.3: 0.80%, N.sub.2: 0%, C.sub.2H.sub.4: 0.5%, H.sub.2 as remainder J NH.sub.3: 1.0%, H.sub.2: 74% TiCl.sub.4: 0.15%, AlCl.sub.3: 0.40%, N.sub.2: 0%, C.sub.2H.sub.4: 0.2%, H.sub.2 as remainder Comparative film A NH.sub.3: 4.0%, H.sub.2: 78% TiCl.sub.4: 0.30%, AlCl.sub.3: 0.30%, N.sub.2: 3%, C.sub.2H.sub.4: 0.5%, H.sub.2 as remainder forming process B NH.sub.3: 3.0%, H.sub.2: 73% TiCl.sub.4: 0.30%, AlCl.sub.3: 0.50%, N.sub.2: 0%, C.sub.2H.sub.4: 0.0%, H.sub.2 as remainder C NH.sub.3: 2.7%, H.sub.2: 70% TiCl.sub.4: 0.50%, AlCl.sub.3: 0.90%, N.sub.2: 0%, C.sub.2H.sub.4: 0.0%, H.sub.2 as remainder D NH.sub.3: 2.7%, H.sub.2: 78% TiCl.sub.4: 0.50%, AlCl.sub.3: 1.20%, N.sub.2: 0%, C.sub.2H.sub.4: 0.5%, H.sub.2 as remainder E NH.sub.3: 2.5%, H.sub.2: 72% TiCl.sub.4: 0.30%, AlCl.sub.3: 0.80%, N.sub.2: 5%, C.sub.2H.sub.4: 0.0%, H.sub.2 as remainder F NH.sub.3: 0.8%, H.sub.2: 75% TiCl.sub.4: 0.30%, AlCl.sub.3: 0.50%, N.sub.2: 7%, C.sub.2H.sub.4: 0.0%, H.sub.2 as remainder G NH.sub.3: 0.8%, H.sub.2: 71% TiCl.sub.4: 0.50%, AlCl.sub.3: 0.90%, N.sub.2: 5%, C.sub.2H.sub.4: 0.0%, H.sub.2 as remainder H NH.sub.3: 0.7%, H.sub.2: 70% TiCl.sub.4: 0.30%, AlCl.sub.3: 1.10%, N.sub.2: 0%, C.sub.2H.sub.4: 0.5%, H.sub.2 as remainder I NH.sub.3: 0.7%, H.sub.2: 70% TiCl.sub.4: 0.50%, AlCl.sub.3: 1.00%, N.sub.2: 0%, C.sub.2H.sub.4: 0.5%, H.sub.2 as remainder J NH.sub.3: 0.6%, H.sub.2: 75% TiCl.sub.4: 0.25%, AlCl.sub.3: 1.20%, N.sub.2: 0%, C.sub.2H.sub.4: 0.0%, H.sub.2 as remainder
TABLE-US-00005 TABLE 5 Forming conditions (pressure of reaction atmosphere is expressed as kPa and temperature is expressed as C.) First stage film formation conditions (formation of initial film formation layer) Phase Gas group A Gas group B difference Supply Supply in supply time time between Formation of hard per per gas group coating layer Supply one Supply one A and gas Process Formation period period period period group B Reaction atmosphere type symbol (sec) (sec) (sec) (sec) (sec) Pressure Temperature Present A 1 0.05 1 0.05 0.04 5.0 700 invention B 1.2 0.05 1.2 0.05 0.04 5.0 750 film C 1.2 0.05 1.2 0.05 0.04 5.0 700 forming D 2 0.12 2 0.12 0.09 4.5 700 process E 1.5 0.10 1.5 0.10 0.05 5.0 700 F 1.5 0.10 1.5 0.10 0.05 4.5 700 G 2 0.12 2 0.12 0.05 4.5 800 H 2 0.12 2 0.12 0.09 4.7 700 I 2 0.05 2 0.05 0.05 4.7 750 J 2 0.05 2 0.05 0.05 4.7 800 Comparative A film B forming C 2 0.2 2 0.2 0.25 4 680 process D 3 0.2 3 0.2 0.2 2.5 700 E 2.5 0.2 2.5 0.2 0.2 4 750 F G 3 0.2 3 0.2 0.25 4.7 680 H 4 0.15 4 0.15 0.2 5.0 800 I J Forming conditions (pressure of reaction atmosphere is expressed as kPa and temperature is expressed as C.) Second stage film formation conditions Phase Gas group A Gas group B difference Supply Supply in supply time time between Formation of hard per per gas group coating layer Supply one Supply one A and gas Process Formation period period period period group B Reaction atmosphere type symbol (sec) (sec) (sec) (sec) (sec) Pressure Temperature Present A 1 0.05 1 0.05 0.04 5.0 800 invention B 1 0.05 1 0.05 0.04 5.0 800 film C 2 0.12 2 0.12 0.09 4.5 800 forming D 2 0.12 2 0.12 0.09 4.5 800 process E 1.5 0.10 1.5 0.10 0.05 5.0 750 F 1.5 0.10 1.5 0.10 0.05 5.0 700 G 1 0.05 1 0.05 0.05 5.0 800 H 1 0.12 1 0.12 0.09 4.7 700 I 2 0.12 2 0.12 0.09 4.7 750 J 2 0.12 2 0.10 0.09 4.7 800 Comparative A 3 0.12 3 0.12 0.15 6.0 650 film B 3 0.2 3 0.2 0.15 5.0 700 forming C 1 0.2 1 0.2 0.25 4.0 680 process D 3 0.2 3 0.2 0.2 4.7 700 E 4 0.2 4 0.2 0.2 6.0 750 F 3 0.15 3 0.15 0.2 5.0 750 G 3 0.2 3 0.2 0.25 4.7 800 H 3 0.2 3 0.2 0.25 5.0 700 I 1.5 0.2 1.5 0.2 0.15 5.0 700 J 2 0.2 2 0.2 0.25 6.0 650
TABLE-US-00006 TABLE 6 Lower layer (numerical value at the Upper layer bottom indicates the (numerical value at the average target layer bottom indicates the thickness of the layer average target layer Tool (m)) thickness of the layer body First Second Third (m)) Type symbol layer layer layer First layer Second layer Present 1 A invention coated 2 B TiN tool (0.3) Comparative 3 C TiN Al.sub.2O.sub.3 coated tool (0.2) (2) 4 D TiN 1-TiCN (0.3) (2) 5 A 6 B 7 D 8 C TiC 1-TiCN 1-TiCN Al.sub.2O.sub.3 (1.5) (2.5) (0.5) (1) 9 A TiN 1-TiCN TiCNO TiCNO (0.5) Al.sub.2O.sub.3 (0.2) (3) (0.5) (2) 10 B
TABLE-US-00007 TABLE 7 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1xAl.sub.x) (C.sub.yN.sub.1y) Periodic Formation symbol concentration variation of TiAlCN film Presence or absence Tool forming process Average Average of concentration body (see Tables 4 amount amount variation of Period Type symbol and 5) X.sub.avg of Al Y.sub.avg of C present invention (nm) Present 1 A A 0.95 0.0001 or Present 1 invention less coated tool 2 B B 0.77 0.0001 or Present 2 less 3 C C 0.64 0.0001 or Present 8 less 4 D D 0.4 0.0001 or Present 15 less 5 A E 0.50 0.0001 or Present 12 less 6 B F 0.39 0.0001 or Present 9 less 7 C G 0.35 0.0001 or Present 3 less 8 D H 0.24 0.0050 Present 10 9 A I 0.85 0.0033 Present 12 10 B J 0.71 0.021 Present 11 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1xAl.sub.x) (C.sub.yN.sub.1y) Periodic concentration Hexagonal fine Target film variation crystal grains thickness of Area Area Average initial layer of Target ratio ratio grain first stage film total film (% by (% by size R formation thickness Type x area) area) (m) (m) (m) Present 1 0.03 54 7 0.24 0.5 4.0 invention coated tool 2 0.05 67 2 0.06 0.5 4.0 3 0.07 39 2 0.11 0.5 3.5 4 0.16 33 0.5 2.0 5 0.1 38 2 0.03 1.0 3.5 6 0.11 39 1 0.01 0.5 5.0 7 0.01 44 0.5 1.5 8 0.12 36 0.5 1.0 9 0.14 40 5 0.32 0.5 3.5 10 0.11 57 6 0.3 1.0 4.0 (Note 1) Any of Xavg, Yavg, and x in boxes indicates atomic ratio. (Note 2) Presence or absence of concentration variation of present invention in boxes indicates Present in a case where the minimum angle of the angle between a direction in which the period of a periodic concentration variation is minimized and the surface of a tool body is 30 degrees or less and indicates Absent in a case where the minimum angle is more than 30 degrees.
TABLE-US-00008 TABLE 8 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1xAl.sub.x) (C.sub.yN.sub.1y) Formation Periodic concentration variation Hexagonal fine Target film symbol of Presence or crystal grains thickness of TiAlCN film absence of Area Area initial layer Target forming concentration ratio ratio Average of first total Tool process (see Average Average variation of (% (% grain stage film film body Tables 4 and amount amount present Period by by size R formation thickness Type symbol 5) X.sub.avg of Al Y.sub.avg of C invention (nm) x area) area) (m) (m) (m) Comparative 1 A A 0.5 0.0036 3 0.05 3.5 coated tool 2 B B 0.63 0.0001 or Absent* 12 0.08 0 5.0 less 3 C C 0.7 0.0001 or 10 0.02 0.8 5.0 less 4 D D 0.7 0.0033 10 0.09 0.7 3.5 5 A E 0.65 0.0001 or Absent* 25 0.11 0 1 0.05 0.7 4.0 less 6 B F 0.55 0.0001 or Absent* 50 0.05 0 7 0.11 4.0 less 7 C G 0.55 0.0001 or 7 0.1 0.5 3.5 less 8 D H 0.72 0.0025 Absent* 12 0.07 0 15 0.34 1.0 3.5 9 A I 0.6 0.0035 11 0.15 5.0 10 B J 0.77 0.0001 or 29 0.28 5.0 less (Note 1) Mark * in boxes indicates outside of the range of the present invention. (Note 2) in boxes indicates that there is no periodic concentration variation or there are no hexagonal fine crystal grains. (Note 3) Presence or absence of concentration variation of present invention in boxes indicates Present in a case where the minimum angle of the angle between a direction in which the period of a periodic concentration variation is minimized and the surface of a tool body is 30 degrees or less and indicates Absent in a case where the minimum angle is more than 30 degrees. (Note 4) Any of Xavg, Yavg, and x in boxes indicates atomic ratio.
[0100] 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 10 and the comparative coated tools 1 to 10 were subjected to wet high-speed face milling, which is a type of high-speed intermittent cutting of alloy steel, and a center-cut cutting test, which will be described below, and the flank wear width of a cutting edge was measured.
[0101] The results are shown in Table 9.
[0102] Tool body: tungsten carbide-based cemented carbide, titanium carbonitride-based cermet
[0103] Cutting test: wet high-speed face milling, center-cut cutting work
[0104] Cutter diameter: 125 mm
[0105] Work material: a block material of JIS SCM440 with a width of 100 mm and a length of 400 mm
[0106] Rotational speed: 994 min.sup.1
[0107] Cutting speed: 390 m/min
[0108] Depth of cut: 3.0 mm
[0109] Feed per tooth: 0.2 mm/tooth
[0110] Cutting time: 6 minutes.
[0111] (a typical cutting speed is 220 m/min)
TABLE-US-00009 TABLE 9 Flank wear Cutting test width results Type (mm) Type (min) Present 1 0.13 Comparative 1 3.1* invention 2 0.13 coated 2 5.1* coated tool 3 0.15 tool 3 4.7* 4 0.18 4 3.5* 5 0.17 5 4.2* 6 0.17 6 3.1* 7 0.17 7 2.5* 8 0.18 8 3.4* 9 0.14 9 2.9* 10 0.15 10 3.0* Mark * in boxes of comparative coated tools indicates a cutting time (min) until the end of a service life caused by the occurrence of chipping.
Example 2
[0112] As raw material powders, a WC powder, a TiC powder, a ZrC powder, a TaC powder, a 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 to 3 m, 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 green compacts having predetermined shapes at a pressure of 98 MPa, and the green compacts were sintered in a vacuum at 5 Pa under the condition that the green compacts were held at a predetermined temperature in a range of 1370 C. to 1470 C. for one hour. After the sintering, each of tool bodies E to G made of WC-based cemented carbide with insert shapes according to ISO standard CNMG120412 was produced by performing honing with R: 0.07 mm on a cutting edge portion.
[0113] In addition, as raw material powders, a TiCN (TiC/TiN=50/50 in terms of mass ratio) powder, a NbC powder, a WC powder, a Co powder, and a Ni powder, all of which had an average grain size of 0.5 to 2 m, 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 a green compact at a pressure of 98 MPa, and the green compact was sintered in a nitrogen atmosphere at 1.3 kPa under the condition that the green compact was held at a temperature of 1500 C. for one hour. After the sintering, a tool body H made of TiCN-based cermet with an insert shape according to ISO standard CNMG120412 was produced by performing honing with R: 0.09 mm on a cutting edge portion.
[0114] Subsequently, present invention coated tools 11 to 20 were produced by forming (Ti.sub.1-xAl.sub.x)(C.sub.yN.sub.1-y) layers shown in Table 13 on the surfaces of the tool bodies E to G and the tool body H through a thermal CVD method for a predetermined time using a typical chemical vapor deposition apparatus under the forming conditions A to J shown in Tables 4 and 5.
[0115] In addition, a lower layer and an upper layer shown in Table 12 were formed in the present invention coated tools 11 to 20 under the forming conditions shown in Table 3.
[0116] In addition, for the purpose of comparison, comparative coated tools 11 to 20 shown in Table 14 were produced by depositing a hard coating layer on the surfaces of the same tool bodies E to G and the tool body H to have target layer thicknesses under the conditions shown in Tables 4 and 5 using a typical chemical vapor deposition apparatus, like the present invention coated tools.
[0117] In addition, like the present invention coated tools 11 to 20, a lower layer and an upper layer shown in Table 12 were formed in the comparative coated tools 11 to 20 under the forming conditions shown in Table 3.
[0118] The section of each of constituent layers of the present invention coated tools 11 to 20 and the comparative coated tools 11 to 20 was measured using the scanning electron microscope (at a magnification of 5,000). 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 13 and 14.
[0119] In addition, regarding the hard coating layers of the present invention coated tools 11 to 20 and the comparative coated tools 11 to 20, using the same method as that described in Example 1, the average amount X.sub.avg of Al and the average amount Y.sub.avg of C were measured.
[0120] The results are shown in Tables 13 and 14.
[0121] It was confirmed through line analysis by energy-dispersive X-ray spectroscopy (EDS) using the transmission electron microscope (at a magnification of 200,000) that a periodic composition distribution of Ti and Al was present in the cubic crystal grains 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 20, and the difference x between the average of local maximums and the average of local minimums of x was obtained.
[0122] Furthermore, the period of the concentration variation of Ti and Al was obtained by observing a small area of the crystal grains having the cubic structure in which the periodic concentration variation was present using the same transmission electron microscope and performing area analysis from the section side using energy-dispersive X-ray spectroscopy (EDS).
[0123] In addition, regarding the layer of a complex nitride or complex carbonitride, the crystal structure, the average grain size R, and the area ratio of the hexagonal fine crystal grains present at the grain boundaries between the crystal grains having a NaCl type face-centered cubic structure were measured using the transmission electron microscope and an electron backscatter diffraction apparatus.
[0124] The results are shown in Tables 13 and 14.
TABLE-US-00010 TABLE 10 Mixing composition (mass %) Type Co TiC ZrC TaC NbC Cr.sub.3C.sub.2 TiN WC Tool E 6.5 1.5 2.9 0.1 1.5 Remainder body F 7.6 2.6 4.0 0.5 1.1 Remainder G 6.0 Remainder
TABLE-US-00011 TABLE 11 Mixing composition (mass %) Type Co Ni NbC WC TiCN Tool body H 11 4 6 15 Remainder
TABLE-US-00012 TABLE 12 Lower layer (numerical Upper layer (numerical value at the bottom value at the bottom indicates the average indicates the average target layer thickness of target layer thickness Tool the layer (m)) of the layer (m)) body First Second Third First Second Type symbol layer layer layer layer layer Present 11 E TiN invention coated (0.3) tool .Math. 12 F TiN l-TiCN A1.sub.2O.sub.3 Comparative (0.3) (4) (5) coated tool 13 G 14 H 15 E TiN l-TiCN (0.3) (7) 16 F TiN l-TiCN TiCNO (0.2) (5) (0.5) 17 H 18 G TiC l-TiCN l-TiCN A1.sub.2O.sub.3 (0.5) (5) (0.8) (3.2) 19 E TiN l-TiCN TiCNO TiCNO (0.5) A1.sub.2O.sub.3 (0.2) (5) (0.5) (5) 20 F TiN TiCNO (1) A1.sub.2O.sub.3 (0.3) (3.5)
TABLE-US-00013 TABLE 13 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1xAl.sub.x)(C.sub.yN.sub.1y) Target Formation film symbol of thickness TiAlCN Periodic concentration variation Hexagonal fine of film Presence or crystal grains initial Target forming absence of Area Area layer total process Average Average concentration ratio ratio Average of film Tool (see amount amount variation (% (% grain first thick- body Tables X.sub.avg Y.sub.avg of present Period by by size R formation ness Type symbol 4 and 5) of Al of C invention (nm) x area) area) (m) (m) (m) Present 11 E A 0.94 0.0001 or Present 2 0.04 50 9 0.18 1.0 10.0 invention less coated 12 F B 0.78 0.0001 or Present 2 0.04 61 1 0.08 1.0 16.0 tool less 13 G C 0.63 0.0001 or Present 9 0.06 44 2 0.1 0.5 7.0 less 14 H D 0.39 0.0001 or Present 14 0.11 31 0 1.0 12.0 less 15 E E 0.50 0.0001 or Present 13 0.08 37 1 0.02 1.0 8.0 less 16 F F 0.37 0.0001 or Present 8 0.09 44 1 0.02 2.0 10.0 less 17 H G 0.35 0.0001 or Present 4 0.01 55 0 0.5 11.0 less 18 G H 0.25 0.0050 Present 11 0.15 38 0 2.0 17.0 19 E I 0.85 0.0038 Present 13 0.15 48 6 0.31 0.5 15.0 20 F J 0.72 0.0025 Present 13 0.13 52 7 0.34 3.0 20.0 (Note 1) Any of Xavg, Yavg, and x in boxes indicates atomic ratio. (Note 2) Presence or absence of concentration variation of present invention in boxes indicates Present in a case where the minimum angle of the angle between a direction in which the period of a periodic concentration variation is minimized and the surface of a tool body is 30 degrees or less and indicates Absent in a case where the minimum angle is more than 30 degrees.
TABLE-US-00014 TABLE 14 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1xAl.sub.x)(C.sub.yN.sub.1y) Formation symbol Target of film TiAlCN Periodic concentration variation thickness film Presence or Hexagonal fine of initial forming absence of crystal grains layer process concentration Area Area Average of first Target Tool (see Average Average variation ratio ratio grain stage film total film body Tables 4 amount amount of present Period (% by (% by size R formation thickness Type symbol and 5) X.sub.avg of Al Y.sub.avg of C invention (nm) x area) area) (m) (m) (m) Comparative 11 E A 0.5 0.0036 3 0.05 12.0 coated tool 12 F B 0.62 0.0001 Absent* 10 0.1 0 15.0 or less 13 G C 0.71 0.0001 12 0.02 0.8 7.0 or less 14 H D 0.7 0.0033 14 0.09 0.7 10.0 15 E E 0.65 0.0001 Absent* 31 0.15 0 2 0.05 0.7 10.0 or less 16 F F 0.55 0.0001 Absent* 48 0.08 0 5 0.12 10.0 or less 17 H G 0.54 0.0001 8 0.11 0.5 13.0 or less 18 G H 0.72 0.0025 Absent* 11 0.03 0 16 0.35 1.0 17.0 19 E I 0.6 0.0035 12 0.15 15.0 20 F J 0.78 0.0001 29 0.31 19.0 or less (Note 1) Mark * in boxes indicates outside of the range of the present invention. (Note 2) in boxes indicates that there is no periodic concentration variation or there are no hexagonal fine crystal grains. (Note 3) Presence or absence of concentration variation of present invention in boxes indicates Present in a case where the minimum angle of the angle between a direction in which the period of a periodic concentration variation is minimized and the surface of a tool body is 30 degrees or less and indicates Absent in a case where the minimum angle is more than 30 degrees. (Note 4) Any of Xavg, Yavg, and x in boxes indicates atomic ratio.
[0125] 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 20 and the comparative coated tools 11 to 20 were subjected to a wet high-speed intermittent cutting test for stainless steel, and a wet high-speed intermittent cutting test for cast iron, which will be described below, and the flank wear width of a cutting edge was measured in either case.
[0126] Cutting conditions 1:
[0127] Work material: a round bar with four longitudinal grooves formed at equal intervals in the longitudinal direction of JIS SUS304
[0128] Cutting speed: 300 m/min
[0129] Depth of cut: 1.5 mm
[0130] Feed: 0.2 mm/rev
[0131] Cutting time: 2 minutes,
[0132] (a typical cutting speed is 150 m/min)
[0133] Cutting conditions 2:
[0134] Work material: a round bar with four longitudinal grooves formed at equal intervals in the longitudinal direction of JIS FCD800
[0135] Cutting speed: 350 m/min
[0136] Depth of cut: 2.0 mm
[0137] Feed: 0.3 mm/rev
[0138] Cutting time: 3 minutes,
[0139] (a typical cutting speed is 200 m/min)
[0140] The results of the cutting test are shown in Table 15.
TABLE-US-00015 TABLE 15 Flank wear width Cutting test results (mm) (min) Cutting Cutting Cutting Cutting Type conditions 1 conditions 2 Type conditions 1 conditions 2 Present 11 0.13 0.13 Comparative 11 0.8 1.5 invention 12 0.12 0.12 coated tool 12 1.5 2.3 coated tool 13 0.13 0.15 13 1.2 2.5 14 0.14 0.17 14 1.3 2.4 15 0.14 0.18 15 1.6 2.9 16 0.16 0.17 16 1.2 1.3 17 0.17 0.19 17 0.8 1.5 18 0.16 0.18 18 1.4 2.8 19 0.14 0.14 19 0.9 1.2 20 0.13 0.15 20 1.2 2.6 Mark * in boxes of comparative coated tools indicates a cutting time (min) until the end of a service life caused by the occurrence of chipping.
Example 3
[0141] 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 in a range of 0.5 to 4 m, were prepared, and the raw material powders were mixed in mixing compositions shown in Table 16. The mixture was subjected to wet mixing by a ball mill for 80 hours and was dried. Thereafter, the resultant was press-formed into green compacts having dimensions with a diameter of 50 mm and a thickness of 1.5 mm at a pressure of 120 MPa, and the green compacts were then sintered in a vacuum atmosphere at a pressure of 1 Pa under the condition that the green 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 and a holding time of 0.8 hours at a predetermined temperature in a range of 1200 C. to 1400 C. 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) of JIS standard CNGA120408 using a brazing filler metal made of a TiZrCu 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, each of tool bodies a and b with an insert shape according to ISO standard CNGA120408 was produced by performing honing with a width of 0.13 mm and an angle of 25 on a cutting edge portion and performing finish polishing on the resultant.
TABLE-US-00016 TABLE 16 Mixing composition (mass %) Type TiN TiC Al A1.sub.2O.sub.3 cBN Tool body a 50 5 3 Remainder b 50 4 3 Remainder
[0142] 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 using a typical chemical vapor deposition apparatus to have target layer thicknesses under the conditions shown in Tables 4 and 5 in the same method as that in Example 1.
[0143] In addition, a lower layer and an upper layer shown in Table 17 were formed in the present invention coated tools 21 to 30 under the forming conditions shown in Table 3.
[0144] In addition, for the purpose of comparison, comparative coated tools 21 to 26 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 4 and 5 using a typical chemical vapor deposition apparatus.
[0145] In addition, like the present invention coated tools 21 to 30, a lower layer and an upper layer shown in Table 17 were formed in the comparative coated tools 21 to 30 under the forming conditions shown in Table 3.
[0146] The section of each of constituent layers of the present invention coated tools 21 to 30 and the comparative coated tools 21 to 30 was measured using the scanning electron microscope (at a magnification of 5,000). 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 18 and 19.
[0147] In addition, regarding the hard coating layers of the present invention coated tools 21 to 30 and the comparative coated tools 21 to 30, using the same method as that described in Example 1, the average amount X.sub.avg of Al and the average amount Y.sub.avg of C were measured.
[0148] Furthermore, using the same method as that described in Example 1, the period of the periodic concentration variation of Ti and Al present in the cubic crystal grains, the difference x between the average of local maximums and the average of local minimums of x in the concentration variation, the crystal structure, the average grain size R, and the area ratio of the hexagonal fine crystal grains present at the grain boundaries between the individual crystal grains having a NaCl type face-centered cubic structure were measured.
[0149] The results are shown in Tables 18 and 19.
TABLE-US-00017 TABLE 17 Upper layer Lower layer (numerical (numerical value at value at the bottom the bottom indicates the indicates the average average target layer target layer Tool thickness of thickness body the layer (m)) of the Type symbol First layer Second layer layer (m)) Present invention 21 a coated tool .Math. 22 b TiN l-TiCN Al.sub.2O.sub.3 Comparative (0.3) (1.0) (1.5) coated tool 23 a 24 b 25 a 26 a 27 b TiN l-TiCN (0.2) (0.8) 28 a TiC l-TiCN (0.5) (1.5) 29 b 30 a TiN l-TiCN (0.3) (1.0)
TABLE-US-00018 TABLE 18 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1xAl.sub.x)(C.sub.yN.sub.1y) Formation symbol Target of film TiAlCN Periodic concentration variation thickness film Presence or Hexagonal fine of initial forming absence of crystal grains layer process concentration Area Area Average of first Target Tool (see Average Average variation ratio ratio grain stage film total film body Tables 4 amount amount of present Period (% by (% by size R formation thickness Type symbol and 5) X.sub.avg of Al Y.sub.avg of C invention (nm) x area) area) (m) (m) (m) Present 21 a A 0.95 0.0001 or Present 2 0.05 54 7 0.22 0.5 2.0 invention less coated tool 22 b B 0.79 0.0001 or Present 3 0.04 63 2 0.05 0.5 1.5 less 23 a c 0.65 0.0001 or Present 8 0.05 48 2 0.09 0.5 2.5 less 24 b D 0.39 0.0001 or Present 12 0.12 30 0 0.5 3.0 less 25 a E 0.50 0.0001 or Present 11 0.09 35 2 0.04 0.6 3.0 less 26 b F 0.36 0.0001 or Present 6 0.11 39 4 0.06 0.6 2.5 less 27 a G 0.36 0.0001 or Present 4 0.02 48 0 0.4 1.5 less 28 b H 0.24 0.0051 Present 9 0.13 39 0 0.4 1.0 29 a I 0.84 0.0036 Present 14 0.14 50 9 0.29 0.4 1.0 30 b J 0.72 0.0023 Present 13 0.11 58 6 0.36 0.4 1.5 (Note 1) Any of Xavg, Yavg, and x in boxes indicates atomic ratio. (Note 2) Presence or absence of concentration variation of present invention in boxes indicates Present in a case where the minimum angle of the angle between a direction in which the period of a periodic concentration variation is minimized and the surface of a tool body is 30 degrees or less and indicates Absent in a case where the minimum angle is more than 30 degrees.
TABLE-US-00019 TABLE 19 Hard coating layer Layer of complex nitride or complex carbonitride of Ti and Al (Ti.sub.1xAl.sub.x)(C.sub.yN.sub.1y) Formation symbol Target of film TiAlCN Periodic concentration variation thickness film Presence or Hexagonal fine of initial forming absence of crystal grains layer process concentration Area Area Average of first Target Tool (see Average Average variation ratio ratio grain stage film total film body Tables 4 amount amount of present Period (% by (% by size R formation thickness Type symbol and 5) X.sub.avg of Al Y.sub.avg of C invention (nm) x area) area) (m) (m) (m) Present 21 a A 0.5 0.0039 1 0.06 1.5 invention 22 b B 0.63 0.0001 Absent* 12 0.1 0 2.0 coated or less tool 23 a C 0.71 0.0001 1 0 0.8 2.0 or less 24 b D 0.7 0.0034 10 0.06 0.7 3.0 25 a E 0.66 0.001 Absent* 30 0.12 0 1 0.06 0.7 1.5 or less 26 b F 0.55 0.0001 Absent* 54 0.04 0 5 0.12 1.5 or less 27 a G 0.55 0.0001 8 0.11 0.5 2.0 or less 28 b H 0.72 0.0027 Absent* 20 0.1 0 14 0.34 1.0 1.5 29 a I 0.61 0.0035 13 0.16 1.0 30 b J 0.77 0.0001 30 0.33 2.0 or less (Note 1) Mark * in boxes indicates outside of the range of the present invention. (Note 2) in boxes indicates that there is no periodic concentration variation or there are no hexagonal fine crystal grains. (Note 3) Presence or absence of concentration variation of present invention in boxes indicates Present in a case where the minimum angle of the angle between a direction in which the period of a periodic concentration variation is minimized and the surface of a tool body is 30 degrees or less and indicates Absent in a case where the minimum angle is more than 30 degrees. (Note 4) Any of Xavg, Yavg, and x in boxes indicates atomic ratio.
[0150] 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 30 and the comparative coated tools 21 to 30 were subjected to a dry high-speed intermittent cutting work test for cast iron, which will be described below, and the flank wear width of a cutting edge was measured.
[0151] Tool body: cubic boron nitride-based ultrahigh-pressure sintered body
[0152] Cutting test: dry high-speed intermittent cutting work for cast iron
[0153] Work material: a round bar with eight longitudinal grooves formed at equal intervals in the longitudinal direction of JIS FCD800
[0154] Cutting speed: 300 m/min
[0155] Depth of cut: 0.1 mm
[0156] Feed: 0.2 mm/rev
[0157] Cutting time: 3 minutes
[0158] The results of the cutting test are shown in Table 20.
TABLE-US-00020 TABLE 20 Flank Cutting wear test width results Type (mm) Type (min) Present invention 21 0.13 Comparative coated 21 1.8 coated tool 22 0.14 tool 22 2.2 23 0.16 23 2.7 24 0.18 24 2.4 25 0.17 25 2.6 26 0.18 26 1.6 27 0.19 27 1.4 28 0.18 28 2.5 29 0.14 29 2.0 30 0.16 30 2.2 Mark * in boxes of comparative coated tools indicates a cutting time (min) until the end of a service life caused by the occurrence of chipping.
[0159] From the results shown in Tables 9, 15, and 20, regarding the coated tools of the present invention, since the periodic concentration variation of Ti and Al was present in the direction at an angle of 30 degrees or less with respect to the plane parallel to the surface of the tool body in the crystal grains having a NaCl type face-centered cubic structure constituting the layer of a complex nitride or complex carbonitride of Al and Ti included in the hard coating layer, a cushioning action against the shear force during cutting work occurs. Therefore, the propagation and development of cracks were suppressed, and the toughness was improved.
[0160] Therefore, even in a case of being used for high-speed intermittent cutting work during which intermittent and impact loads were exerted on a cutting edge, chipping resistance and fracture resistance were excellent, and as a result, excellent wear resistance was exhibited during long-term use.
[0161] Contrary to this, it was apparent that in the comparative coated tools in which the periodic concentration variation specified in the present invention was not present in the crystal grains having a NaCl type face-centered cubic structure constituting the layer of a complex nitride or complex carbonitride of Al and Ti included in the hard coating layer, in a case of being used for high-speed intermittent cutting work during which high-temperature heat is generated and intermittent and impact loads are exerted on a cutting edge, the end of the service life thereof was reached within a short time due to the occurrence of chipping, fracture, and the like.
INDUSTRIAL APPLICABILITY
[0162] 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, cast iron, stainless steel, and the like and further exhibits excellent chipping 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.