JP2007224374A - Coated member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated member whose coagulation properties and affinity with a workpiece, and chipping resistance are improved, and having excellent wear resistance. <P>SOLUTION: The coated member coated with a hard coating film has the outermost surface layer film-deposited using physical vapor deposition, wherein the outermost surface layer contains aluminum oxide and Nb, and the hard coating film is composed of any of nitride, boride, carbide or oxide comprising two or more kinds selected from Ti, Al, Cr, Si and Nb as metal components of at least one layer different from the outermost surface layer, or their solid solution or mixture. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a covering member containing aluminum oxide and Nb in the outermost layer.

  Patent Document 1 discloses a technique of a coated tool having an aluminum oxide film as an outermost layer. Patent Documents 2 and 3 disclose techniques for coating an oxide film such as aluminum oxide by physical vapor deposition.

JP 2005-262356 A JP-A-5-57507 JP 2005-138210 A

Patent Document 1 discloses a technique in which an oxide layer formed using a solid deposition source is used as a coated tool having excellent heat resistance and toughness and wear resistance. It is described that the surface roughness Rmax value of the oxide layer is less than 0.3 μm, and the oxide layer contains an element selected from Al, Zr, Si, Cr, Ti, and B. However, the surface roughness Rmax value of the oxide layer is defined not by the value of the outermost surface but by the value measured from the cross section of the coating layer. In addition, improvement in adhesion resistance and adhesion resistance with the workpiece is not considered. Patent Document 2 discloses a technique in which the outermost layer is made of an aluminum oxide film, the surface roughness Ra is 0.4 μm or less, and the tool edge part is processed by polishing for the purpose of improving the welding resistance of the tool edge part. is doing. The coated cutting tool of Patent Document 3 discloses a technique in which a coating layer has an inner layer and an outer layer, the inner layer is formed of a hard coating, and the outer layer is formed of aluminum oxide. A part of aluminum oxide is a coated cutting tool which is amorphous and has compressive stress and is coated by physical vapor deposition. However, the aluminum oxide coated by the physical vapor deposition method of Patent Documents 2 and 3 has coarse crystal grains and has a protruding shape. There is a problem that peeling or abnormal wear occurs due to the work piece adhering to the crystal grains having a drop-off or protruding shape.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a covering member that improves adhesion, affinity, and fracture resistance with a workpiece and has excellent wear resistance.

  The covering member of the present invention is a covering member having an outermost layer formed by physical vapor deposition, and the outermost layer contains aluminum oxide and Nb. By adopting the above configuration, it is possible to improve the adhesion, affinity, and fracture resistance with the workpiece and to provide a covering member having excellent wear resistance.

  In the outermost layer of the covering member of the present invention, it is preferable to substitute one part of Nb with one or more selected from Ti, Cr, Si, and B. At least one layer different from the outermost layer is any one of nitride, boride, carbide and oxide containing two or more selected from Ti, Al, Cr, Si, and Nb as a metal component, or those It is preferable to provide a hard film comprising a solid solution or a mixture of the above. In the covering member of the present invention, the surface roughness Ra, Ry of the outermost layer is (μm), Ra ≦ 0.03, Ry ≦ 0.5, and the outermost layer is smoothed by mechanical treatment. It is effective.

  According to the present invention, it was possible to provide a covering member having improved wear resistance, affinity and fracture resistance with a workpiece, and having excellent wear resistance.

  By containing aluminum oxide and Nb in the outermost layer of the covering member of the present invention, adhesion to the workpiece, affinity, and fracture resistance are improved, and excellent wear resistance is achieved. The Nb content is atomic%, preferably in the range of 0.1% to 30%. The reason is considered that when Nb is contained in the range of 0.1% to 30% in aluminum oxide, there is an effect of reducing the crystal grain size. By controlling the surface roughness of the aluminum oxide film surface to a small state, adhesion of the workpiece can be reduced. Furthermore, the wear characteristics can be improved. By miniaturizing the crystal grain size of aluminum oxide, the surface was smoothed, and the adhesion, affinity and fracture resistance with the workpiece were improved. On the other hand, if Nb is less than 0.1%, the effect of refining the crystal grain size cannot be obtained. On the other hand, if it exceeds 30%, the wear resistance of the aluminum oxide film is inferior, which is inconvenient. The coating of the present invention is preferably physical vapor deposition (hereinafter referred to as PVD). This is because compressive residual stress can be applied to the film. Preferable PVD includes sputtering and arc discharge ion plating (hereinafter referred to as AIP). When adding various elements, PVD can be easily added to the aluminum oxide film by preparing a metal target material containing Nb as an additive element in advance. That is, the element addition is possible by simultaneously operating the vapor deposition source 1 equipped with the aluminum oxide target and the vapor deposition source 2 equipped with the metal target containing the additive element in the vacuum apparatus. Examples of the crystal structure of the aluminum oxide film include α-type, γ-type, κ-type, and amorphous phase. The effect of the present invention can also be obtained in any of these cases or when they are mixed. A preferred crystal structure is α-type aluminum oxide.

The outermost layer of the covering member of the present invention is a further improvement in the adhesion and wear resistance of the hard coating by replacing one part of Nb with one or more selected from Ti, Cr, Si, B. Has an effect. The amount of substitution is atomic%, preferably in the range of 0.1% to 30%. The reason for this is considered that the substitution of Ti, Cr, Si, and B has an effect on the refinement of the crystal grain size of aluminum oxide. Furthermore, Ti and Si elements are effective in increasing the hardness of the film. Cr and B are effective in improving adhesion. In addition to the above, it is considered that the addition of W and V elements has an effect on the refinement of the crystal grain size. On the other hand, if the substitution amount is less than 0.1%, the above effect cannot be obtained. On the other hand, if it exceeds 30%, the wear resistance of the aluminum oxide film is inferior, which is inconvenient.
At least one layer different from the outermost layer is any one of nitride, boride, carbide and oxide containing two or more selected from Ti, Al, Cr, Si, and Nb as a metal component, or those It is effective and preferable in order to ensure the adhesiveness of the base material of a coating | coated member and a membrane | film | coat, and to improve abrasion resistance. These hard coatings are a preferred layer structure because they are used in the lower layer of the aluminum oxide coating, have excellent adhesion strength with the aluminum oxide coating, and can make the crystal grains of the aluminum oxide coating finer. Examples of the hard coating include (AlTi) N, (TiSi) N, (AlSi) N, (AlTiSi) N, (AlCr) N, (AlCrSi) N, and (TiSiB) N. These are excellent in adhesion strength with an aluminum oxide film, and are suitable for making crystal grains of an aluminum oxide layer fine.
The Ra value and Ry value of the outermost layer are preferably Ra ≦ 0.03 μm and Ry ≦ 0.5 μm. By controlling within this range, the unevenness of the crystal particles on the surface of the aluminum oxide film is small, and adhesion of the workpiece to the crystal particles can be minimized in a wear environment. In addition, the effect of having an aluminum oxide film on the outermost layer is sufficiently exhibited while avoiding peeling and falling off of crystal grains. On the other hand, when the surface roughness of the aluminum oxide layer is in the range of Ra> 0.03 μm and Ry> 0.5 μm, the effect of covering the aluminum oxide film cannot be obtained in a wear environment. The reason for this is that the workpiece adheres to the crystal particles due to the unevenness of the crystal particles on the surface of the aluminum oxide film in a wear environment, and induces peeling or dropping of the crystal particles. Therefore, in the present invention, the surface of the aluminum oxide film is preferably set to Ra ≦ 0.03 μm and Ry ≦ 0.5 μm. The measuring method of Ra value and Ry value is based on JIS standard. The measuring device can be measured by a contact-type surface roughness measuring device, a non-contact three-dimensional roughness measuring device, an atomic force microscope, or the like. The site | part which measures the surface roughness of this invention has a preferable site | part which contacts a workpiece in a wear environment. For example, in a cutting tool, the flank of the cutting edge is preferable.
As a means for setting the surface roughness of the outermost layer to a preferable value of the present invention, it is preferable to perform a mechanical treatment after coating the aluminum oxide film. Examples of the mechanical treatment include grinding and polishing. In particular, mirror finishing with a projection material containing diamond particles is suitable. By performing a mechanical treatment after coating, non-metallic elements such as carbon and oxygen are contained in the aluminum oxide film on the nanometer order, thereby improving the wear resistance. In particular, when the oxygen and / or carbon concentration becomes maximum in the depth region within 100 nm in the film thickness direction from the aluminum oxide surface layer, it is effective in suppressing adhesion of the workpiece to the hard coating surface.

  When the base material of the covering member of the present invention is composed of any of WC-based cemented carbide, cermet, high speed steel, ceramics, cubic boron nitride sintered body and diamond sintered body, excellent wear resistance It is preferable because it exhibits its properties. The WC-based cemented carbide preferably has an average particle size of WC of 0.2 μm or more and less than 0.6 μm, and the Co content is preferably 3 to 8% by weight for achieving the effects of the present invention. The covering member of the present invention is particularly effective for suppressing wear of a cutting tool, and examples thereof include an end mill, a drill, a tap, and an insert tool. When the present invention is applied to, for example, a cutting tool, it exhibits excellent wear resistance in an environment where the temperature is very high and the workpiece tends to adhere, such as high speed and dry processing, and can be processed for a long time. it can. Also, when applied to wear-resistant tools such as dies, bearings, dies, and rolls, it is possible to extend the life. Hereinafter, a description will be given based on examples.

  The coating of the hard coating of the present invention was performed by the AIP method and the unbalanced magnetron sputtering (hereinafter referred to as UBMS) method. A plurality of AIP evaporation sources and UBMS evaporation sources were arranged in the film forming apparatus, and a cemented carbide base material was mounted on a rotatable holder on the front surface of the evaporation source. The base material was made of a WC-based cemented carbide alloy, WC particle size: 0.6 to 0.8 μm, Co content: 8 wt%, a two-blade 10 mm diameter blade-end replaceable ball end mill containing Cr and Ta. . A predetermined metal target material was set in the AIP evaporation source, and aluminum oxide was set in the UBMS evaporation source. And after evacuating the inside of the film-forming apparatus to 5 * 10 <-3> Pa or less, the base material was heated to 500 degreeC and hold | maintained for 1 hour. A voltage of −300 V was applied to the base material in a state where Ar gas was introduced from the gas inlet and the inside of the film forming apparatus was kept at 2 Pa. Glow discharge was generated in Ar gas, and the substrate surface was cleaned with Ar ions. After applying a predetermined bias voltage to the substrate, the AIP evaporation source is subjected to vacuum arc discharge, and nitrogen gas or, if necessary, gas containing carbon or oxygen is introduced into the film forming apparatus from the gas inlet, and the lower layer Formed. Add metal elements other than aluminum to the aluminum oxide layer by introducing Ar and oxygen gas from the gas inlet into the deposition system and simultaneously discharging the aluminum component and other metal components from separate UBMS evaporation sources did. The lower layer was coated with a thickness of about 3 μm, and the outermost film containing aluminum oxide and Nb was coated with about 1 μm. The aluminum oxide film was formed after sufficiently oxidizing the surface of the lower layer so that the lower layer and the outermost aluminum oxide film grew continuously. Note that the coating of the lower layer and the coating of the aluminum oxide layer are not necessarily performed continuously by the same film forming apparatus. In consideration of the crystal stability of the aluminum oxide film, it may be preferable to treat the lower layer and the aluminum oxide film with separate film forming apparatuses. Invention Examples 1 to 17 were prepared by the above method. The surface roughness Ra and Ry values of Invention Examples 1 to 17 were measured with a contact-type surface roughness measuring device. If necessary, the substrate before coating was mirror-finished so that the Ra value was 0.01 μm or less. To adjust the surface roughness, the surface roughness was adjusted by a mechanical method after coating. The adopted mechanical method was to project a projection material containing diamond onto the surface of the hard coating. Table 1 shows the hard coating composition and surface roughness.

  Invention Examples 1 to 17 show cases where the metal component shown in Table 1 was added and a metal element other than aluminum was added to the aluminum oxide film when the outermost aluminum oxide film was coated. FIG. 1 shows an electron micrograph of Example 1 of the present invention subjected to mechanical treatment. Protrusion-like aluminum oxide crystal particles were not clearly observed. Further, almost no aluminum oxide crystal particles having a convex shape were observed. FIG. 2 shows an electron micrograph of Comparative Example 18 in which no mechanical treatment was performed. Crystal grains of aluminum oxide having protrusions were clearly confirmed.

In order to evaluate the hard coating, the wear resistance of the cutting tool was evaluated. Evaluation of adhesion, affinity, fracture resistance, and wear resistance with the workpiece was performed under the following cutting conditions. The life judgment was the cutting length until the maximum wear width reached 0.1 mm. However, less than 10 m was rounded down and shown in Table 1.
(Cutting conditions)
Processing method: Dry processing, bottom straight processing, down cut processing Workpiece: FCD450
Cutting speed: 160 m / min Feed amount per blade: 0.3 mm / blade Cutting depth: 0.25 mm in the axial direction, pick feed 0.5 mm
The inventive examples were superior in wear resistance compared to the comparative examples, and the effects of the present invention were confirmed. In FIG. 3, the abrasion resistance evaluation result of this invention example 1 and the comparative examples 18 and 20 is shown. In Invention Example 1, there was no peeling of the aluminum oxide film, and a significant improvement in wear characteristics was observed. From Inventive Examples 1 to 3, the wear resistance due to the difference in surface roughness was compared. In addition to the addition of the Nb element, the substitution of one part of Nb with another element resulted in smaller Ra and Ry values, which resulted in excellent wear resistance. Invention Example 1 and Invention Examples 4 to 6 show cases where the crystal structures of the aluminum oxide films are different. In any crystal structure, excellent wear resistance was exhibited. Invention Example 7 shows a case where (AlCr) N is present in the lower layer. Invention Example 8 is (AlCrSi) N, Invention Example 9 is (AlTiSiN), Invention Example 10 is coated with (AlTi) N and (SiTi) N, and then coated with an aluminum oxide film. Invention Example 11 shows a case where (AlTi) N and (AlCrSi) N are coated and then an aluminum oxide film is coated. In any case, the effect of improving the wear resistance was confirmed. Invention Example 12 shows a case in which the lower layer is (AlZr) N, but a film containing two or more selected from Ti, Al, Cr, Si, and Nb was more preferable in the lower layer. Inventive Example 13 includes (AlTiNb) N in the lower layer, Inventive Example 14 includes (AlTi) N, and Inventive Examples 15 to 17 are formed of NbCr, NbV, NbTiB on the aluminum oxide film. The case where each element was added was shown, and all were excellent in abrasion resistance.

  FIG. 4 shows an electron micrograph of the vicinity of the cutting edge of Comparative Example 18 in the initial stage of cutting. In Comparative Example 18, peeling of the aluminum oxide layer was observed at the beginning of cutting. The reason for this is that, since there was adhesion of a large number of workpieces to the aluminum oxide crystal particles with protrusions immediately after the start of cutting, peeling occurred with the growth of these adhesions. is there. Therefore, the aluminum oxide film on the outermost layer had a large number of adherents, a large amount of peeling occurred from the lower layer, and the aluminum oxide layer did not function. In Comparative Examples 18 and 19, as in the case where the aluminum oxide layer of Comparative Example 20 was not on the surface, no improvement in wear resistance was observed.

FIG. 1 shows a surface electron micrograph of Example 1 of the present invention. FIG. 2 shows a surface electron micrograph of Comparative Example 18. FIG. 3 shows the wear curve. FIG. 4 shows an electron micrograph of the vicinity of the cutting edge of Comparative Example 18.

Claims (5)

A covering member coated with a hard film, wherein the covering member has an outermost layer formed by physical vapor deposition, and the outermost layer contains aluminum oxide and Nb. 2. The covering member according to claim 1, wherein the outermost layer is formed by replacing one part of Nb with one or more selected from Ti, Cr, Si, and B. 3. The covering member according to claim 1 or 2, wherein the covering member includes a layer different from the outermost layer, and contains two or more kinds selected from Ti, Al, Cr, Si, and Nb as metal components. A covering member comprising a hard film made of any one of boride, carbide and oxide, or a solid solution or a mixture thereof. The covering member according to any one of claims 1 to 3, wherein the surface roughness Ra, Ry of the outermost layer is (µm), and Ra ≤ 0.03, Ry ≤ 0.5. Element. 5. The covering member according to claim 1, wherein the outermost layer is smoothed by a mechanical treatment.