Surface-coated cutting tool with hard coating layer exhibiting excellent chipping resistance and wear resistance

Abstract

A surface-coated cutting tool with a hard coating layer exhibits excellent chipping resistance and wear resistance in a high-speed cutting process. The surface-coated cutting tool comprises a lower layer consisting of a titanium compound layer and an upper layer consisting of an aluminum oxide layer deposited on a surface of a tool substrate constituted of a tungsten carbide-based cemented carbide as a hard coating layer. In the upper layer, a (006) plane texture coefficient TC(006) is 1.8 or more, a ratio I(104)/I(110) of a peak intensity I(104) of an (104) plane to a peak intensity I(110) of an (110) plane is in a range of 0.5 to 2.0, and furthermore, an absolute value of a residual stress in the aluminum oxide layer is 100 MPa or less.

Claims

1. A surface-coated cutting tool comprising; a tool substrate constituted of a tungsten carbide-based cemented carbide; a lower layer consisting of a titanium compound layer; and an upper layer consisting of an aluminum oxide layer, wherein the lower layer is deposited on a surface of the tool substrate, the lower and upper layers are formed as hard coating layers, the upper layer is deposited directly on a surface of the lower layer, and the upper layer has; 1.8 or more of a (006) plane texture coefficient TC(006), 0.5 to 2.0 of a ratio I(104)/I(110) of a peak intensity I(104) of an (104) plane to a peak intensity I(110) of an (110) plane, and 100 MPa or less of an absolute value of a residual stress.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) 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, wherein like designations denote like elements in the various views, and wherein:

(2) FIG. 1 illustrates an X-ray diffraction chart obtained from measurements in an upper layer of a coated tool of the invention, and the locations and peak intensity values I(hkl) of (hkl) planes.

DETAILED DESCRIPTION OF THE INVENTION

Best Mode for Carrying Out the Invention

(3) Next, the coated tool of the invention will be specifically described using examples.

EXAMPLES

(4) WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr.sub.3C.sub.2 powder, TiN powder and Co powder all of which had an average grain diameter in a range of 1 μm to 3 μm were prepared as powder-form raw materials, and the powder-form raw materials were blended in accordance with the blending compositions described in Table 1. Wax was further added, and the mixture was mixed using a ball mill for 24 hours in acetone, depressurized, dried, and then pressed into a powder compact having a predetermined shape with a pressure of 98 MPa. The powder compact was vacuum-sintered in a vacuum of 5 Pa at a predetermined temperature in a range of 1370° C. to 1470° C. under a condition of one-hour holding, and, after sintering, a 0.07 mm-radius honing process was carried out on a cutting edge section, thereby manufacturing WC-based cemented carbide tool substrates A and B having an insert shape described in ISO•CNMG 120408.

(5) Next, Ti compound layers described in Table 3 were deposited on surfaces of the tool substrates A and B as the lower layer of the hard coating layer using an ordinary chemical deposition device under conditions described in Table 2,

(6) subsequently, an Al.sub.2O.sub.3 layer was deposited on a surface of each of the Ti compound layers under three-phase conditions described in Table 4,

(7) and then, a wet blast treatment was carried out on a rake surface and/or a flank surface, including a ridge line section of a cutting edge, under conditions described in Table 5, thereby manufacturing invention coated tools 1 to 10 described in Table 6.

(8) In addition, for the purpose of comparison, Ti compound layers described in Table 3 were deposited under the conditions described in Table 2 as the lower layer of the hard coating layer,

(9) subsequently, an Al.sub.2O.sub.3 layer was deposited under conditions described in Table 7, and then a wet blast treatment was carried out under the conditions described in Table 5, thereby manufacturing comparative coated tools 1 to 10 described in Table 8.

(10) The layer thicknesses of the Ti compound layers and the Al.sub.2O.sub.3 layers on the rake surfaces, the flank surfaces and the ridge line sections of the cutting edge of the invention coated tools and the comparative coated tools were measured using a scanning electron microscope, X-ray diffraction was carried out on the Al.sub.2O.sub.3 layers, TC(006) was obtained by measuring the X-ray diffraction peak intensities from the respective planes of (012), (104), (110), (006), (113), (202), (024) and (116), and furthermore, a peak intensity ratio I(104)/I(110) was obtained from the respective values of the peak intensities I(104) and I(110) from (104) and (110).

(11) Tables 6 and 8 describe the values.

(12) In addition, for the Al.sub.2O.sub.3 layers in the invention coated tools and the comparative coated tools, the values of residual stresses were measured using a sin.sup.2 ψ method and an X-ray diffraction device. The diffraction peak of αAl.sub.2O.sub.3 on the (13_10) plane was used for the measurement, and computation was carried out using a Young's modulus of 384 GPa and a Poisson's ratio of 0.232.

(13) Tables 6 and 8 describe the values.

(14) TABLE-US-00001 TABLE 1 Blending composition (mass %) Type Co TiC ZrC TaC NbC Cr.sub.3C.sub.2 TiN WC Tool 5.5 1 — 3.2 0.5 — 0.8 balance substrate A Tool 6.8 1 0.5 2.1 0.5 0.3 — balance substrate B

(15) TABLE-US-00002 TABLE 2 Forming conditions (the units for the pressure and temperature of the reaction atmosphere are Component kPa and ° C.) layers of hard Reaction gas coating layer composition Reaction atmosphere Type Symbol (volume %) Pressure Temperature TiC TiC TiCl.sub.4:4.2%, CH.sub.4:8.5%, 7 1020 H.sub.2: balance TiN (first TiN TiCl.sub.4:4.2%, N.sub.2:30%, 30 900 layer) H.sub.2: balance TiN (other TiN TiCl.sub.4:4.2%, N.sub.2:35%, 50 1040 layers) H.sub.2: balance I-TiCN I-TiCN TiCl.sub.4:2%, CH.sub.3CN:0.7%, 7 900 N.sub.2:10%, H.sub.2: balance TiCN TiCN TiCl.sub.4:2%, CH.sub.4:1%, 13 1000 N.sub.2:15%, H.sub.2: balance TiCO TiCO TiCl.sub.4:4.2%, CO:4%, 7 1020 H.sub.2: balance TiCNO TiCNO TiCl.sub.4:2%, CO:1%, 13 1000 CH.sub.4:1%, N.sub.2:5%, H.sub.2: balance

(16) TABLE-US-00003 TABLE 3 Total layer Lower layer of hard coating layer thickness of Tool (Ti compound layer) lower substrate First Second Third Fourth Fifth layer Type symbol layer layer layer layer layer (mm) Invention 1 A TiN I-TiCN TiN TiC TiCO 7 coated (1) (4) (0.5) (1) (0.5) tools and 2 B TiN TiCN TiN I-TiCN — 10 comparative (0.1) (2) (0.4) (7.5) coated tools 3 A TiN I-TiCN TiCO — — 3 (0.3) (2.5) (0.2) 4 A TiN I-TiCN TiN TiCNO — 8 (1) (6) (0.5) (0.5) 5 B TiN I-TiCN TiCNO — — 13 (1) (11) (1) 6 B TiN TiC I-TiCN TiN TiCNO 10 (0.5) (1) (7) (1) (0.5) 7 B TiN TiCN I-TiCN TiCO — 5 (0.5) (1) (3) (0.5) 8 A TiN I-TiCN TiN TiCO — 8 (1) (5) (1.5) (0.5) 9 B TiN TiC I-TiCN TiCO — 9 (0.5) (2) (6) (0.5) 10 A TiN I-TiCN TiN TiCNO — 15 (1) (13) (0.5) (0.5) (Note) numeric values in parenthesis for the respective layers are target layer thicknesses (μm).

(17) TABLE-US-00004 TABLE 4 Film-forming conditions (the units for the pressure and temperature of the reaction atmosphere are kPa and ° C.) Al.sub.2O.sub.3 layer Reaction gas composition Reaction atmosphere Type (volume %) Pressure Temperature A First AlCl.sub.3:0.7 , CO.sub.2:0.1, 6 950 phase HCl:2.1 , CO:1.5, CH.sub.4:0.5, Ar:28.2 , H.sub.2: balance Second A1Cl.sub.3:1.0, CO.sub.2:1.2, 8.5 1020 phase HCl:2.1, H.sub.2S:0.5, Ar:29.0, H.sub.2: balance Third AlCl.sub.3:2.0, CO.sub.2: 1.5, 8.5 1020 phase HCl:5.2, H.sub.2S:0.2, H.sub.2: balance B First AlCl.sub.3:0.5, CO.sub.2:1.0, 10.5 980 phase HCl:3.0, CO:0.1, CH.sub.4:2.0, Ar:35.0 , H.sub.2: balance Second AlCl.sub.3:5.0, CO.sub.2:0.1, 10.5 1000 phase HCl:3.0, H.sub.2S:1.0, Ar:35.0, H.sub.2: balance Third AlCl.sub.3:2.0, CO.sub.2:0.1, 13 1050 phase HCl :7.0 , H.sub.2S:0.4, H.sub.2: balance C First AlCl.sub.3:2.0 , CO.sub.2:1.5, 8 1000 phase HCl:0.3, CO:1.1, CH.sub.4:1.5, Ar:20.0, H.sub.2: balance Second AlCl.sub.3:2.5, CO.sub.2:2.0, 8 1000 phase HCl:0.3, H.sub.2S:0.5, Ar:20.0, H.sub.2: balance Third AlCl.sub.3:0.5, CO.sub.2:0.8, 9 1050 phase HCl:4.0, H.sub.2S:0.02, H.sub.2: balance

(18) TABLE-US-00005 TABLE 5 Wet blast treatment Treatment Surfaces to type be treated Treatment conditions A Rake surface Al.sub.2O.sub.3 grains in polishing and flank solution: 30 mass %, blast surface pressure: 0.20 MPa B Rake surface Al.sub.2O.sub.3 grains in polishing solution: 40 mass %, blast pressure: 0.25 MPa C Flank surface Al.sub.2O.sub.3 grains in polishing solution: 40 mass %, blast pressure: 0.18 MPa

(19) TABLE-US-00006 TABLE 6 Upper layer (Al.sub.2O.sub.3 layer) Peak Peak Absolute Lower layer intensity on intensity Wet value of Tool Layer Al.sub.2O.sub.3 Layer TC(006) of measurement ratio blast residual substrate thickness layer thickness Measurement measurement surface I (104)/ treatment stress Type symbol Type (μm) type (μm) surface surface I (104) I (110) I (110) type (MPa) Invention 1 A 1 7 A 8 Rake 2 1356 954 1.4 B 82 coated surface tools 2 B 2 10 C 5 Flank 2.4 1391 1119 1.2 A 41 surface 3 A 3 3 A 10 Rake 3.2 1016 1985 0.5 B 54 surface 4 A 4 8 B 2 Flank 1.8 1888 1359 1.4 C 70 surface 5 B 5 13 B 4 Flank 2.8 2341 1201 2 C 19 surface 6 B 6 10 C 4 Flank 3 2015 1251 1.6 A 75 surface 7 B 7 5 A 15 Flank 1.9 1770 1008 1.8 C 36 surface 8 A 8 8 A 3 Rake 1.8 1518 1723 0.9 B 10 surface 9 B 9 9 C 10 Flank 2.2 1690 1568 1.1 A 35 surface 10 A 10 15 B 2 Flank 2.6 1652 2250 0.7 A 100 surface

(20) TABLE-US-00007 TABLE 7 Film-forming conditions (the units for the pressure and temperature of the reaction atmosphere are kPa and ° C.) Al.sub.2O.sub.3 layer Reaction gas composition Reaction atmosphere Type (volume %) Pressure Temperature a First AlCl.sub.3:1.5, CO.sub.2:0.5, 8.5 1000 phase HCl:0.5, H.sub.2: balance Second AlCl.sub.3:2.5 , CO.sub.2:0.5, 8.5 1000 phase HCl:0.5 , H.sub.2S:0.01, H.sub.2: balance Third AlCl.sub.3:3.2, CO.sub.2:0.8, 13 1020 phase HCl:1.2, H.sub.2S:0.2, H.sub.2: balance b First AlCl.sub.3:0.8, CO.sub.2:1.2, 10 1000 phase HCl:1.1, CO:0.5, Ar:16.5, H.sub.2: balance Second AlCl.sub.3:0.8, CO.sub.2:0.8, 10 1020 phase HCl:1.0, H.sub.2S:0.1, H.sub.2: balance Third AlCl.sub.3:4.2, CO.sub.2:1.5, 7 1050 phase HCl:1.5, H.sub.2S:0.2, H.sub.2: balance c First AlCl.sub.3:2.8, CO.sub.2:1.5, 9 950 phase HCl:1.5, CO:1.8, Ar:25.0, H.sub.2: balance Second AlCl.sub.3:3.5, CO.sub.2:1.5, 9 980 phase HCl:1.2, H.sub.2S:0.5, Ar:10, H.sub.2: balance Third AlCl.sub.3:4.0, CO.sub.2:1.5, 15 980 phase HCl:1.2, H.sub.2S:0.6, H.sub.2: balance

(21) TABLE-US-00008 TABLE 8 Upper layer (Al.sub.2O.sub.3 layer) Peak Peak Absolute Lower layer intensity on intensity Wet value of Tool Layer Al.sub.2O.sub.3 Layer TC(006) of measurement ratio blast residual substrate thickness layer thickness Measurement measurement surface I (104)/ treatment stress Type symbol Type (μm) type (μm) surface surface I (104) I (110) I (110) type (MPa) Comparative 1 A 1 7 c 8 Rake 3.2 2440 536 4.6 B 518 coated tool surface 2 B 2 10 a 5 Flank 0.7 665 2519 0.3 A 108 surface 3 A 3 3 a 10 Rake 2.5 2805 992 2.8 B 430 surface 4 A 4 8 b 2 Flank 0.2 818 2662 0.3 C 82 surface 5 B 5 13 c 4 Flank 0 876 2011 0.4 C 311 surface 6 B 6 10 b 4 Flank 2.2 2696 1280 2.1 A 355 surface 7 B 7 5 a 15 Flank 0.3 1051 2154 0.5 C 95 surface 8 A 8 8 b 3 Rake 1.5 2015 980 2.1 B 361 surface 9 B 9 9 c 10 Flank 0 1157 1643 0.7 A 56 surface 10 A 10 15 a 2 Flank 0.9 1871 649 2.9 A 448 surface

(22) Next, a high-speed dry cutting test (the ordinary cutting speed was 200 m/min) was carried out in a state in which all the invention coated tools and the comparative coated tools were screwed at the front end section of a tool steel cutting holder using fixing jigs under conditions of

(23) material to be cut: ductile cast iron rods,

(24) cutting speed: 350 m/min,

(25) cutting depth: 1.5 mm,

(26) feed: 0.3 mm/rev, and

(27) cutting time: 10 minutes,

(28) thereby measuring the flank wear width of the cutting edge.

(29) The measurement results were described in Table 9.

(30) TABLE-US-00009 TABLE 9 Cutting Flank wear test Type width (mm) Type result Invention 1 0.28 Comparative 1 2 coated 2 0.25 coated tool 2 2.8 tool 3 0.25 3 2.3 4 0.32 4 3.2 5 0.21 5 2 6 0.24 6 1.8 7 0.22 7 3.5 8 0.29 8 2.6 9 0.22 9 2.3 10 0.19 10 1.5 (Note) Numeric values in the cutting test result column for the comparative coated tools indicate the cutting time (minutes) elapsed until the service life ends due to chipping, fracture and the like resulting from cracks generated in the vicinity of the ridge line section of the cutting edge.

(31) From the results described in Tables 6, 8 and 9, it is found that, since the upper layers of the hard coating layers are constituted of an Al.sub.2O.sub.3 layer in which the TC(006) is 1.8 or more, the peak intensity ratio I(104)/I(110) is in a range of 0.5 to 2.0, and furthermore the absolute value of the residual stress value in the upper layer is 100 MPa or less, the invention coated tools 1 to 10 exhibit excellent wear resistance over long-term use without causing the generation of abnormal damage such as chipping or fracture in the ridge line section of the cutting edge in a high-speed cutting process of high-toughness ductile cast iron.

(32) On the contrary, in the comparative coated tools 1 to 10, it is evident that tensile stress in the Al.sub.2O.sub.3 layer is not sufficiently alleviated, and therefore chipping, fracture and the like occur in the cutting edge section, and the service life ends within a relatively short period of time.

INDUSTRIAL APPLICABILITY

(33) As described above, the coated tool of the invention exhibits excellent wear resistance along with excellent chipping resistance in a high-speed cutting process of a high-toughness difficult-to-cut material such as ductile cast iron and exhibits excellent cutting performance over a long period of time, and therefore the coated tool can sufficiently satisfy the improvement of the performance of a cutting device and the labor saving and energy saving, and furthermore, cost reduction in a cutting process.