JP2009160692A - Coated tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated tool having such a high hardness, a high oxidation-resistance and a high wear-resistance as to restrain the occurrence of accidental chipping or abnormal wear. <P>SOLUTION: The substrate of a tool is coated with a film by physical vapor deposition so that the film comprises A layers and B layers wherein the A layers include oxide of Cr as a main base and nitride and boride as a sub-base while the B layers include Al and oxide of Cr as a main base, and nitride and boride as a sub-base, and the film forms a lamination of the A layer and the B layer superimposed on top of each other, wherein when the thickness (nm) of the A layer is TA, and the thickness (nm) of the B layer is TB, the TA and TB values become TA≤50, and TB≤50 respectively, and when the film thickness ratio is TA/TB, the value becomes 1≤TA/TB≤5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coated tool having both wear resistance and oxidation resistance by coating a tool base with a film mainly composed of oxide, nitride and boride by physical vapor deposition. In particular, the present invention relates to a coated tool such as a cutting tool and a wear-resistant tool such as a mold.

  Patent Documents 1 to 3 disclose techniques related to a coated tool in which an oxide film is coated by a physical vapor deposition method. Further, Patent Document 4 discloses a technique related to a coated tool in which two types of compound thin films are laminated.

JP 2002-53946 A JP 2006-28600 A JP-A-5-208326 Japanese Patent No. 3460287

  The film of the present invention has both high hardness and excellent oxidation resistance, and by covering the tool, sudden chipping and abnormal wear are suppressed, thereby providing a coated tool with excellent wear resistance. .

  In the present invention, a tool substrate is coated with a film by physical vapor deposition, and the film has an A layer and a B layer, and the A layer is an oxidation of elements of Group 4a, 5a, 6a of the periodic table, Si, Y, boron. One or more selected from oxides, nitrides and borides, the B layer is selected from Group 4a, 5a and 6a elements of the periodic table, Al, Si, Y, boron oxides, nitrides and borides In a coated tool having two or more types and coated with the A layer and the B layer, the A layer is mainly composed of an oxide of Cr, nitride and boride as sub-substances, and the B layer is composed of Al, Cr The oxide is mainly composed of nitride and boride as sub-substances, and the film has an alternate layer structure of the A layer and the B layer, the layer thickness (nm) of the A layer is TA, and the B layer When the layer thickness (nm) is TB, the TA value and the TB value are TA ≦ 50 and TB ≦ 50, respectively, and when the film thickness ratio is TA / TB, 1 ≦ TA / TB ≦ 5. It is coated tool according to claim. By adopting the above configuration, the coating of the present invention has both high hardness and excellent oxidation resistance, and by covering the tool, the occurrence of sudden chipping and abnormal wear is suppressed, and the wear resistance is excellent. A coated tool is obtained.

  The coated tool of the present invention preferably has a TA value and a TB value of TA ≦ 30 and TB ≦ 30, respectively. In the A layer, one part of Cr is replaced with one or more selected from Si, W, and boron, and in the B layer, one part of Al and Cr is selected from Nb, Si, W, Y, and boron. It is preferable to substitute as described above. Further, an intermediate layer containing nitride is coated between the tool substrate and the coating, the outermost surface is coated with the outermost layer containing nitride, the B layer is coated on the tool substrate side, and the A layer is coated on the surface side. It is preferable.

  The coating of the present invention has high hardness and excellent oxidation resistance, and by covering the tool, sudden chipping and abnormal wear are suppressed, and a coated tool with excellent wear resistance can be provided. It was.

The coating of the present invention combines high hardness, excellent oxidation resistance, thermal stability and smoothness, and suppresses sudden chipping and abnormal wear of the tool, thereby improving the wear resistance. In the coated tool in which the tool base is coated by the PVD method, the coating of the present invention is a coated tool having a laminated structure in which the A layer and the B layer are alternately formed to have a layer thickness of 50 nm or less. The crystal structure of the B layer has a corundum structure.
The coating of the present invention has an alternating layer structure of A layers and B layers, and has oxide as a main component, nitride and boride as sub-substances, and has higher hardness than, for example, an aluminum oxide film. By alternately laminating the A layer and the B layer, the B layer grows while maintaining a corundum structure, and at the same time, the A layer and the B layer are laminated with crystals having substantially the same crystal structure and different face spacings, This is because lattice strain occurs between the two layers. This lattice strain maintains substantially the same plane spacing in the vicinity of the interface between the two layers, and becomes the individual plane spacing of the A layer and the B layer as it grows. Since the interface between the two layers maintains high adhesion strength and has a high residual compressive stress of 1 GPa or more due to lattice strain, a high hardness of the coating is achieved. This lattice strain also has an effect of suppressing grain growth, and the crystal grains of the A layer and the B layer are made finer. As a result, the smoothness of the coating surface is improved.
The coating of the present invention has an alternating laminated structure, and TA values and TB values of TA ≦ 50 and TB ≦ 50 are important for increasing the hardness and are effective by improving the wear resistance of the tool. Is. In the case of TA> 50, the hardness of the entire film is lowered, so that the wear resistance cannot be improved. Further, when TB> 50, the B layer cannot maintain the corundum structure, so that the hardness of the entire film is lowered and the crystal grain size of the film is coarsened, so that the wear resistance cannot be improved. Further, it is particularly important that the film of the present invention satisfies 1 ≦ TA / TB ≦ 5 from the viewpoint of increasing the hardness of the film, and is effective for improving the wear resistance of the tool. When TA / TB <1, the crystallinity of the film tends to decrease and the film hardness tends to decrease. On the other hand, when TA / TB> 5, the film hardness tends to decrease in the same manner. The reason for the decrease in hardness in the case of TA / TB> 5 is that the ratio of the A layer in the entire film is too large. The TA value and the TB value are controlled by adjusting the rotation speed of the substrate in addition to adjusting the evaporation amount in the metal targets for forming the A and B layers.

  The coating of the present invention has an alternating laminated structure, and when the TA value and TB value are TA ≦ 30 and TB ≦ 30, respectively, the hardness is increased by improving the crystallinity of the coating, the crystal particles are refined and smoothed. The effect of improving the adhesion strength due to the continuity of the crystal growth of the A layer and the B layer is obtained, and it is more effective and effective for improving the wear resistance of the tool.

  In the A layer constituting the film of the present invention, one part of Cr is replaced with one or more selected from Si, W, and boron, and in the B layer, one part of Al and Cr is replaced with Nb, Si, W Substitution with one or more selected from Y, Y and boron is preferred. Here, one or more elements selected from Nb, Si, W, Y, and boron are M elements. Also, when the Al content is x, the Cr content is y, and the M element content is z, where the numerical value is x + y + z = 100 in terms of atomic ratio, it is optimal for achieving the effect of the M element and the present invention. Indicates the content. By replacing a part of Al or Cr in the B layer with Si, the crystal grains of the film are refined and the hardness is increased, so that the wear resistance of the tool is improved. The optimum composition in this case is 50 ≦ x ≦ 90, 10 ≦ y ≦ 50, 0.1 ≦ z ≦ 10, where z is the amount of Si. Further, when the (x + z) value exceeds 70, the film becomes amorphous, the hardness is drastically lowered and the wear resistance is lowered, so 50 ≦ (x + z) ≦ 70 is optimal. By substituting one part of Cr in the B layer with Nb, W, Y, boron, the crystallinity of the corundum structure is improved, so that the Al content can be increased. As a result, the oxidation resistance and heat resistance are improved and the wear resistance is improved. The optimum composition in this case is 50 ≦ x ≦ 90, 10 ≦ y ≦ 50, 0.1 ≦ z ≦ 10, where the z value is the content of the M element. Moreover, by adding W to the AlCr target, droplets are reduced and the smoothness of the film is improved. Further, it is preferable that one part of Cr and Al is substituted with two or three kinds selected from Nb, Si, W, Y, and boron because the same effect is obtained.

  It is preferable to coat an intermediate layer containing nitride between the coating of the present invention and the tool substrate, and to coat the outermost layer containing nitride on the outermost surface. Here, 90% or more of the film containing the nitride of the intermediate layer or outermost layer is nitride, and the balance may include carbide, oxide, boride, or sulfide. This intermediate layer exhibits the role of improving adhesion to the tool base and the wear resistance effect against mechanical wear. The intermediate layer preferably covers one or more layers containing one or more nitrides selected from Al, Ti, Cr, W, Nb, and Si, and the intermediate layer has a thickness of 1 to 12 μm. Is the best. The effect of covering the outermost layer is that the coating of the present invention may exhibit an interference color, so the appearance color is stabilized, and the productivity is improved by ensuring the conductivity around the jigs and evaporation sources in the film forming apparatus. It is. Moreover, the sensor etc. which ensure the electroconductivity of a tool surface and measure a tool dimension electrically can be used. More preferably, the outermost layer covers one or more layers containing one or more nitrides selected from Al, Ti, Cr, W, Nb, and Si, and the outermost layer has a layer thickness of 0.01. A range of ˜3 μm is optimal. In order to improve the adhesion strength between the intermediate layer, the outermost layer, and the coating film of the present invention, formation of a composition mixed layer and formation of a composition gradient layer are also preferable.

  In the laminated structure of the coating of the present invention, the B layer is preferably coated on the tool base side and the A layer is coated on the surface side. When the B layer is on the tool base side, it is possible to obtain an effect as an adhesion strengthening layer, and when the A layer is on the surface side, it is possible to obtain an effect of enhancing oxidation resistance and heat resistance. This is preferable because it is possible.

  The peak shift of 2θ in the X-ray diffraction of the film of the present invention is caused by the shift of the lattice constant. For example, the value of {2θ (B) / 2θ (A)} exceeds 1 on the (116) plane of the A and B layers, In the range of 1.0475 or less, the lattices of the A and B layers continuously grow and have a lattice strain in a state with high adhesion strength, and a high residual compressive stress of 1 GPa or more is given, and the hardness of the coating is increased. And smoothing is achieved simultaneously. This increase in hardness is effective in improving the wear resistance of the tool. The continuity of the crystal lattice can be confirmed by observing a cross-sectional lattice image with a transmission electron microscope. The range of 1 to 6 GPa is optimal for the residual compressive stress of the present invention. If it is less than 1 GPa, defects from thermal cracks are likely to occur during cutting. On the other hand, if it is higher than 6 GPa, the film on the tool edge part is self-destructed, and an adherent tends to be deposited on the edge part, and the fracture resistance tends to be lowered. The residual compressive stress of the film can be controlled by the bias voltage, TA, TB value, reaction pressure, etc. applied to the substrate among the film forming parameters. The coated tool of the present invention is effective for chip dischargeability and chipping suppression of the cutting edge by smoothing the convex portion on the outermost surface by mechanical treatment, and can improve the cutting life. The coated tool of the present invention is particularly preferably a cutting tool used for cutting high hardness steel, stainless steel, heat resistant steel, cast steel, carbon steel, for example, a ball end mill, a multi-blade end mill, an insert, a drill, a cutter, a broach, Reamers, hobs, routers, etc. In addition, excellent wear resistance is exhibited even in molds, punches, etc., and the tool life is extended. The tool base is preferably cemented carbide, cermet, high speed steel, cubic boron nitride sintered body, die steel or the like. The cemented carbide has a Co content of 3 to less than 12% by weight. If it is less than 3%, sudden chipping or chipping of the cutting edge occurs. On the other hand, if it exceeds 12%, the coating effect is reduced, which is not preferable.

Example 1
As the coating method of the present invention, an arc ion plating (hereinafter referred to as AIP) method was used among the PVD methods. The reason for using the AIP method is that coarsening of the crystal grain size can be suppressed at a relatively low temperature, and the crystal grains of the coating can be refined to introduce high residual compressive stress. In the present invention, Ar is not used during film formation, a relatively high gas pressure of 3 to 15 Pa is employed in a mixed gas atmosphere of nitrogen and oxygen, and TA and TB values have an alternately laminated structure of 50 nm or less, respectively. It is characterized by forming a film. In the vacuum container of the used small AIP film forming apparatus, two arc evaporation sources having a magnetic field with a maximum magnetic flux density of 5 mT or more in the vertical direction are mounted on the target surface. The arc evaporation sources are referred to as C1 and C2, respectively. C1 was loaded with a Cr target, and C2 was loaded with an AlCr alloy target. The AlCr alloy target maintained stable discharge with atomic ratios of Al: 50 to 90% and Cr: 10 to 50%. When using an AlCrSi alloy target, stable discharge can be continued in the range of Al: 50 to 80%, Cr: 20 to 50%, and Si: 1 to 10%.
In the present invention, by adopting the following film formation conditions, nitrogen gas reacts to hardly form a nitride, and 90% or more can be present as an oxide. The product was a sub-body. Also, by introducing nitrogen gas, the gas pressure during film formation was increased to reduce the amount of droplets mixed into the film. As a preferred flow rate ratio of oxygen and nitrogen, oxygen: nitrogen was in the range of 1: 100 to 20: 100. The film forming temperature was in the range of 400 to 700 ° C. The bias power source was connected to the substrate, and a negative DC bias voltage was independently applied to the substrate. The negative bias voltage applied to the tool base was in the range of 40 to 250 V, and the arc current was in the range of 80 to 180A. Moreover, although the rotation speed of the tool base depends on the arc current, the TA value and the TB value were controlled to 50 nm or less, respectively, in the range of 2 to 9 rotations per minute. As a substrate for evaluating the hardness, surface roughness, crystal structure, and laminated structure of the coating of the present invention, the Co content is more than 10% by weight, which is mirror-finished so that the surface roughness Ra <10 nm and Ry <100 nm. A test piece of SNMN120408 shape made of a fine particle cemented carbide was used. To evaluate the durability of the coating, a blade end replaceable ball end mill made of an ultrafine particle cemented carbide of Co: 8% by weight was used. Each of the cutting tools was sufficiently degreased and cleaned and placed in a vacuum vessel. In the pre-deposition process, the substrate was cleaned with Ar ions. The substrate was held at a predetermined temperature, and after the internal pressure of the container reached 5 × 10 −3 Pa, Ar gas was introduced, and a bias voltage of −200 V was applied to perform substrate cleaning for 30 minutes. For the coating of the intermediate layer, after cleaning, 1000 sccm of nitrogen was introduced, 150 A power was supplied to C2 at a pressure of 5 to 7 Pa, and the nitride film was coated with about 3 μm. Subsequently, while maintaining the nitrogen gas flow rate, 150 A of electric power was supplied to C1, and a mixed layer of the C1 nitride layer and the C2 nitride layer was coated by 0.1 μm. The outermost layer was coated under substantially the same conditions. Next to the intermediate layer, the film of the present invention was coated at approximately 2 μm with a bias voltage of −100 V in a state where the flow rate-controlled reaction gas was introduced. After cooling the temperature in the container to 200 ° C. or lower, the sample was taken out. The film formation parameters are oxygen, Ar, and nitrogen flow rates during film formation, film formation temperature, substrate rotation speed, power supply to the arc evaporation source, and patterns thereof. Deposition parameters are shown in Table 1.

  In order to analyze the laminated structure such as TA, TB value, film composition, lattice continuity, and crystal structure, cross-sectional observation was performed with a field emission transmission electron microscope (hereinafter referred to as FE-TEM). The film was observed at an acceleration voltage of 200 kV, and the composition of the film was analyzed for an area of 1 nm in diameter by energy dispersive analysis (EDS). For analysis of the crystal structure of the film, a limited-field diffraction image having a diameter of 1250 nm was taken with a camera length of 50 cm. TA and TB values were measured from a cross-sectional photograph of FE-TEM. When the number of layers was less than 10 layers, the average value of all layers was used, and when the number of layers was 10 layers or more, the average value of the number of layers to be measured was used. The value was rounded off to the nearest 10 nm. The smoothness of the film was evaluated by measuring Ra and Rz values with a contact-type surface roughness measuring instrument. Observation of the fracture surface of the film was performed with a field emission scanning electron microscope (hereinafter referred to as FE-SEM). After notching, the sample was forcibly broken and observed at a magnification of 10k. The film hardness was measured using a nanoindentation device. After the specimen was mirror-polished by tilting 5 degrees, a place where the maximum indentation depth was less than about 1/10 of the film thickness within the polished surface of the film was selected. At this time, there was no influence of the substrate even at about 1/5. Ten points were measured under the measurement conditions of an indentation load of 49 mN, a maximum load holding time of 1 second, and a removal speed after loading of 0.49 mN / second, and an average value was obtained. The film hardness of this measurement method is easily influenced by the fine shape of the indenter, the temperature and humidity at the time of measurement, and the surface state of the sample, and the measured value does not necessarily match the Vickers hardness. Therefore, a relative comparison with single crystal Si was performed. The film hardness of single crystal Si was 12 GPa. An X-ray diffraction (XRD) apparatus was used for analysis of the crystal structure of the film. The tube voltage was 120 kV, the tube current was 40 μm, the X-ray source Cukα, the X-ray incident angle was 5 degrees, the X-ray incident slit was 0.4 mm, and 2θ was 20 to 70 degrees. The measurement results are shown in Table 2.

  FIG. 1 shows an FE-SEM image of the cross section of the coating film of Example 6 of the present invention and FIG. Comparing the two film cross-sectional structures, the film cross-sectional structure of Example 6 of the present invention was finer in crystal grains, and the smoothness of the film surface was superior to that of Conventional Example 38. In Conventional Example 38, the particles were coarse and there was a gap between the particles, resulting in low hardness. Further, when the surface roughness was compared, the Ra value of Invention Example 6 was 12 nm, and the Conventional Example 38 was 34 nm. Conventional Example 39 also had a rough surface and low hardness. FIG. 3 shows the XRD diffraction results of Example 1 of the present invention. A peak corresponding to the A layer and a peak corresponding to the B layer were observed. By alternately laminating two types of films having corundum type crystal structures having different lattice constants in the layer thickness direction, lattice strain was generated at the layer interface, and high hardness was achieved. 4 and 5 show the sectional structure analysis results of Example 6 of the present invention. FIG. 4 shows an FE-TEM image of the film cross section, and FIG. 5 shows a limited field diffraction image of 1250 nmφ. From FIG. 4, the existence of an alternate laminated structure was confirmed. The corundum structure was confirmed from the diffraction pattern of the limited field diffraction image of FIG. 6 shows a high-magnification TEM image of the particle indicated by reference numeral 1 in FIG. 4, and FIG. 7 shows a 140 nmφ limited-field diffraction image of the particle indicated by reference numeral 1 in FIG. From FIG. 7, the particles having a stacked structure grew with the same crystal structure. FIG. 8 is a high-magnification TEM image of the particles shown in FIG. 6, and analysis spots 1 and 2 are shown in FIG. 9 shows an analysis spot 1 and FIG. 10 shows a 1 nmφ micro electron diffraction photograph of the analysis spot 2. From the EDS analysis results, analysis spot 1 was layer B and analysis spot 2 was layer A. 8, 9, and 10 confirm that the B layer and the A layer grew epitaxially while maintaining substantially the same crystal structure and orientation, had lattice continuity at the interface, and confirmed good adhesion. FIG. 11 shows a dark field STEM image of the particles of FIG. 8, and Table 3 shows the film composition of the analysis spots 1 to 4 of FIG.

  Table 3 shows values when the analyzed area is 1 μm × 1 μm and 1 nmφ. The analysis spots 1 and 2 in FIGS. 11 and 8 correspond to each other. From FIG. 11 and Table 3, analysis spots 1 and 3 were the B layer, and analysis spots 2 and 4 were the A layer. From the FE-TEM analysis results, the presence of the A layer and the B layer and the TA, TA value, crystal structure, and lattice continuity are clearly shown, and the film of the present invention has high hardness and excellent oxidation resistance, and is excellent. It was confirmed to show wear resistance.

(Example 2)
For the durability evaluation of the coating of the present invention, the wear resistance by a blade end replaceable ball end mill was performed under the following test conditions. The tool used is a cemented carbide insert made by Hitachi Tool, a diameter of 32 mm. The wear resistance was evaluated by the flank wear width after 2300 m processing. A flank wear width of less than 0.15 mm was judged to be effective. The evaluation results are also shown in Table 2.
(Test conditions)
Cutting method: Contour cutting of 10 ° inclined surface Work material: FCD540
Cutting depth: axial direction, 0.3 mm, radial direction, 0.3 mm
Spindle speed: 12,000 revolutions per minute Table feed: 10800 mm / min
1-blade feed amount: 0.45 mm / blade Cutting oil: None, air blow

Inventive Examples 1 and 2 and Comparative Examples 24 and 25 compare the effects of TA, TB values and laminated structure on oxidation resistance and wear resistance by simultaneously operating C1 and C2 and changing the number of rotations of the substrate. did. Invention Examples 1 and 2 having TA and TB values of 50 nm or less gave oxides having a corundum structure, and showed high hardness of 27 GPa or more. The comparative examples 24 and 25 were 22 GPa or less. In Invention Example 3 and Comparative Examples 26 to 33, for comparison of the effects on the characteristics of TA and TB values, C1 and C2 targets were alternately operated, and the laminated structure was changed by changing the period. In Invention Example 3, the B layer was coated on the tool base side and the A layer was coated on the surface side. Invention Example 3 having a TA and TB value of 50 nm or less showed a corundum structure. Comparative Examples 26 to 33 in which at least one of the TA and TB values exceeded 50 nm had a γ-type crystal structure, and the coating film had low hardness and did not improve the wear resistance. In Invention Examples 4 to 8, C1 and C2 were simultaneously operated, the arc current was changed to change the laminated structure, and the effects of the laminated structure were compared. In Invention Examples 4 to 8, a TA and TB value of 50 nm or less and a corundum structure were obtained. The Ra value of Invention Example 6 was 12 nm, and Conventional Example 38 was 34 nm. As a result, the work material adhered and the wear resistance did not improve. Conventional Example 39 also has the disadvantage that the surface is rough and has low hardness, and the work material adheres to the protruding particles, causing the film to fall off and peel off, thereby accelerating the progress of wear. The inventive example was smoothed with high hardness, and the wear width of the cutting tool was less than half that of the conventional example. C1 has an arc current of 100 A or more, and C2 is 100 A or less, so that the TA / TB value becomes 1 or more, the coating hardness increases, the wear width of the cutting tool decreases, and the effect of improving wear resistance is remarkable. It was. Inventive Examples 4 to 8 and Comparative Examples 34, 35 and 36 having no laminated structure were compared. Since Comparative Examples 34 and 35 had a γ-type crystal structure and Comparative Example 36 had an amorphous structure, the wear resistance of the cutting tool could not be improved. In Comparative Example 37, the B layer did not contain Cr and had an amorphous structure, and the wear resistance was inferior to that of Inventive Example 1. In addition, the conventional example 38 in which AlN is coated at 2.8 kW by sputtering after coating with CrN by the AIP method and the conventional example 39 in which the AlCr oxide is coated in the same manner have TA and TB values. Due to the large and rough surface and low hardness, the work material adhered to the protruding oxide particles, and the coating peeled off and the progress of wear was rapid. Furthermore, the conventional examples 40 and 41 coated with (TiAl) N and (AlCr) N, respectively, did not improve the wear resistance.
Invention Examples 6 and 7 having TA and TB values of 30 nm or less were compared with Invention Examples 1 to 5, and 8 of more than 30 nm and 50 nm or less. In Invention Examples 6 and 7, the flank wear width was 0.1 mm or less, the wear state was uniform, sudden chipping and abnormal wear were suppressed, and the oxidation resistance and wear resistance were excellent. By setting the TA and TB values to 30 nm or less, the crystallinity of the coating is improved, and the interface increases while the A and B layers grow epitaxially. As a result, the hardness was increased. Invention Examples 1 to 3 and 5 having a TA / TB value of 1 were compared with Invention Examples 4 and 6 to 8 which were greater than 1. In Invention Examples 4 and 6 to 8, the flank wear width was 0.11 mm or less, the wear state was uniform, the occurrence of sudden chipping and abnormal wear was suppressed, and the oxidation resistance and wear resistance were excellent. When the TA / TB value was large, the crystallinity of the TB layer was improved, and the oxidation resistance and heat stability were improved. Inventive Examples 4 and 6 to 8 in which the lattices of the A layer and the B layer were continuously grown were compared with Inventive Examples 1 to 3 and 5 having no continuous growth. The presence of continuous growth improves the uniformity of the wear state of the cutting edge, suppresses sudden chipping and abnormal wear, and has excellent oxidation resistance and wear resistance. The conditions for continuous growth could be achieved by setting the TB value to 20 nm or less.

  On the other hand, Comparative Examples 9-13 operated only C2, and changed the flow rate ratio of Ar and oxygen to form films. When only Ar was used, it was a γ-type oxide film, and the film surface was rough and low in hardness, and many droplets were observed. In Comparative Examples 14 to 20, only C2 was operated, and the influence of the gas type and the flow rate ratio was compared by changing the flow rate ratio of oxygen and nitrogen. Compared to Ar, the droplets on the surface of the film were reduced and the smoothness was excellent, but it became a γ-type oxide film and had a low hardness. By forming a film using a mixed gas of nitrogen and oxygen, an oxide film having a low nitrogen content and a metal: oxygen ratio of 2: 3 was obtained. In particular, when the nitrogen: oxygen ratio was 7 to 11: 1 to 5, an oxide film excellent in smoothness with a nitrogen content of 3% or less was obtained. In Comparative Examples 17, 21 to 23, the influence of the film formation temperature was compared. In the range of 400 to 700 ° C., all were γ-type oxide films. The crystal structure of the film by the AIP method is independent of temperature, and a corundum type oxide film was obtained even at 600 ° C. or lower. Comparative Example 26 in which the B layer was coated on the A layer was a γ-type oxide film. The wear state was unstable and multiple chippings were confirmed, and the oxidation resistance and wear resistance could not be improved.

(Example 3)
Using the same film forming conditions as in Invention Example 6, Invention Examples 42 to 50 and Comparative Examples 51 and 52 were prepared. Here, the A layer replaces one part of Cr with one or more selected from Si, W, and boron, and the B layer selects one part of Al and Cr from Nb, Si, W, Y, and boron. The effect of substituting with one or more was confirmed. The TA and TB values of Invention Examples 42 to 50 were substantially the same as those of Invention Example 6. Inventive Examples 42 to 50 and Comparative Examples 51 and 52 were all coated with nitride having a C2 composition as an intermediate layer of 2 μm, and the outermost layer was coated with nitride in a range of 0.05 to 0.2 μm. The coating conditions for the intermediate layer were the same as in Example 1. Table 4 shows the target composition used.

  The coating of the present invention was able to improve the oxidation resistance and wear resistance of the cutting tool. With the AlCrNb system of Invention Example 42, a film having a corundum structure was obtained even when the Al content was increased to 75%. Nb contributed to the increase in hardness by promoting corundum formation of the film. Comparing the inventive example 43 and the comparative example 51, it is preferable that the sum of the contents of Al and Si is 70% or less. In particular, with Si, the crystal grains of the film became finer, higher hardness and smoothness were obtained, and wear resistance was improved. In Invention Example 45, the crystal grains became fine and the smoothness improved. W and Y were effective in improving oxidation resistance and effective in improving wear resistance. Boron was effective in improving the lubricity as well as promoting the corundum formation of the film, and was effective in improving the wear resistance. On the other hand, the TA / TB value of Comparative Examples 51 and 52 is larger than the range specified in the present invention, and Comparative Example 51 in which the B layer is an AlCrSi type shows an amorphous structure and low hardness, and the Comparative Example 52 of AlCrTi type is Two types of corundum structure and γ type were confirmed. When Ti was added, the film showed low hardness. This is because coarse Ti oxide is formed and the crystal grain size is increased. In any case, the effect of improving the wear resistance was not obtained.

Example 4
The coating life of the present invention was applied to a solid drill to evaluate the tool life. The solid drill is made by Hitachi Tool, the diameter is 6 mm, the base is made of ultrafine cemented carbide with Co: 10%, and the hardness is HRA92.3. The coating method was the same as in Example 1. After coating about 3 μm of (TiAl) N of the intermediate layer, coatings of Example 6 and Conventional Examples 38 and 39 were coated with approximately 2 μm, which were referred to as Inventive Example 53 and Conventional Examples 54 and 55, respectively. Conventional examples 40 and 41 were coated as conventional examples 56 and 57, respectively. These were evaluated for tool life under the following test conditions. Evaluation was made into the number of the processing holes when the flank wear width of the corner part reached 0.2 mm, or the number of processing holes in which the chipping, chipping or the like that could not be continued. The number of processed holes was cut off less than 100 holes, and the average life of the three holes was determined. The evaluation results are shown in Table 5.
(Test conditions)
Cutting method: blind hole processing, hole depth 6mm
Coolant: MQL internal lubrication Work material: FCD700
Spindle speed: 12k / min Feed: 0.2mm / rotation

  Invention Example 53 showed a long service life of three times or more the number of processed holes as compared with the conventional example, and it was confirmed that the coated drill of the present invention has excellent oxidation resistance and wear resistance.

FIG. 1 shows an FE-SEM image of the film cross section of Example 6 of the present invention. FIG. 2 shows an FE-SEM image of the cross section of the film of Conventional Example 38. FIG. 3 shows the XRD diffraction result of Example 1 of the present invention. FIG. 4 shows a TEM image of a cross section of the film of Example 6 of the present invention. FIG. 5 shows a 1250 nmφ restricted field diffraction image of Example 6 of the present invention. FIG. 6 shows a high-magnification TEM image of the particle indicated by reference numeral 1 in FIG. FIG. 7 shows a 140 nmφ limited-field diffraction image of the particle indicated by reference numeral 1 in FIG. FIG. 8 shows a high-magnification TEM image of the particle indicated by reference numeral 1 in FIG. FIG. 9 shows a microscopic electron diffraction photograph of analysis spot 1 in FIG. FIG. 10 shows a microscopic electron diffraction photograph of the analysis spot 2 in FIG. FIG. 11 shows a dark field STEM image of the particles of FIG.

Explanation of symbols

  1: Particle

Claims (5)

A tool substrate is coated with a film by physical vapor deposition, and the film has an A layer and a B layer, and the A layer is a periodic table 4a, 5a, 6a group element, Si, Y, boron oxide, nitride One or more selected from borides, and the B layer contains two or more selected from Periodic Table 4a, 5a and 6a group elements, Al, Si, Y, boron oxides, nitrides and borides. In the coated tool in which the A layer and the B layer are coated, the A layer is mainly composed of an oxide of Cr, nitride and boride are sub-substances, and the B layer is composed of an oxide of Al and Cr. The main body, nitride, and boride are used as sub-substances, and the film has an alternately laminated structure of the A layer and the B layer, the layer thickness (nm) of the A layer is TA, and the layer thickness of the B layer ( nm) when TB is TA, the TB value is TA ≦ 50 and TB ≦ 50, and when the film thickness ratio is TA / TB, 1 ≦ TA / TB ≦ 5 Coated tools to be. The coated tool according to claim 1, wherein the TA value and the TB value are TA ≦ 30 and TB ≦ 30, respectively. 3. The coated tool according to claim 1, wherein in the layer A, a part of Cr is replaced with one or more selected from Si, W, and boron, and the layer B is formed by replacing a part of Al and Cr with Nb, A coated tool substituted with one or more selected from Si, W, Y, and boron. 4. The coated tool according to claim 1, wherein an intermediate layer containing nitride is coated between the tool base and the coating, and an outermost layer containing nitride is coated on the outermost surface. Feature coated tool. 4. The coated tool according to claim 1, wherein the B layer is coated on the tool base side, and the A layer is coated on the surface side.