JP2747584B2 - Hard film coated member - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hard film-coated member having a hard film formed on a surface, and more particularly to an improvement of a member having a surface coated with an A1 compound useful for a cutting tool. . [Background Art] In recent years, as a cutting tool, a hard film with excellent wear resistance and fracture resistance is formed on the surface of a ceramic base material or a base material made of a cemented carbide by means of a chemical vapor deposition method or the like, thereby improving cutting performance. Things that have been raised are attracting attention. According to such a cutting tool, an Al-based compound such as Al oxide or oxynitride is usually used as the hard film. [Problems to be Solved by the Invention] However, a film made of Al oxide or Al oxynitride provided by a conventional CVD method has a columnar crystal structure by continuous crystal growth. Although the above Al-based compound is excellent in heat resistance and abrasion resistance itself, the toughness of the film itself is low in the columnar crystal structure, and the impact resistance and the heat crack resistance are poor. When such a film is provided on the surface of a tough base material, if the film thickness is large, the toughness of the base material is impaired. Therefore, only a thin film having a thickness of 1 to 4 μm can be provided, and sufficient wear resistance can be obtained. I can't. Therefore, when such a hard film-coated member is used for a cutting tool, there is a drawback that the wear resistance and the chipping resistance are insufficient and the life of the tool cannot be extended. [Objects of the Invention] The present invention has a main object of solving the above problems, and specifically, enhances the strength and toughness of a film of Al oxide or oxynitride, and has abrasion resistance and fracture resistance. An object of the present invention is to provide a long-lasting cutting tool having excellent durability. [Means for Solving the Problems] As a result of repeated studies on the above problems, the present inventors have found that the oxide or oxynitride structure of Al By using a non-columnar structure composed of agglomerates, the toughness of the film can be improved without impairing the abrasion resistance of Al oxide or oxynitride, thereby improving the abrasion resistance and fracture resistance. It has been found that a cutting tool with excellent long life can be obtained. Hereinafter, the present invention will be described with reference to the drawings. Normally, when Al oxide (hereinafter, referred to as Al ₂ O ₃ ) or Al oxynitride (hereinafter, referred to as AlON) is formed by a vapor phase growth method, first, Al ₂ O is formed on a surface on which a film is to be formed. _Three
Alternatively, innumerable nuclei of AlON are generated and the nuclei grow to form a film as a whole. When the film thickness subsequently increases, the crystal grains grow in the direction perpendicular to the substrate, and eventually form a columnar crystal film as shown in the micrograph of FIG. The present invention is to grow a non-columnar crystal structure in which fine crystal grains are aggregated as shown in the micrograph of FIG. 3 without forming a columnar crystal in such a film forming process. Therefore, the effects of the configuration of the present invention will be described with reference to FIGS. FIG. 1 shows the relationship between the thickness of Al ₂ O ₃ and the amount of flank wear, and FIG. 2 shows the relationship between the thickness of Al ₂ O ₃ and the defect rate. It is a comparison with a non-columnar crystal structure. According to FIG. 1, regarding the flank wear, in the columnar crystal structure, when the film thickness is 4 to 5 μm, the wear resistance is most excellent, and the wear amount is 0.
25 mm, whereas the non-columnar structure of the present invention has a thickness of 9 mm.
~ 11μm, wear amount is small and wear amount is 0.15mm
And extremely excellent wear resistance. Furthermore, the film thickness showing good wear resistance is wide, and the film thickness is about 4 to
In the range of 15 μm, more excellent wear resistance than the conventional columnar crystal structure can be obtained. On the other hand, according to FIG. 2, with respect to the columnar crystal structure, when the columnar crystal structure exceeds about 2 μm, the crystallinity ratio sharply increases.
When the thickness exceeds 10 μm, nearly 100% of the defects are lost in the experiment. On the other hand, in the non-columnar structure of the present invention, the defect rate is as low as 30% even at a film thickness of 10 μm. . This result means that the non-columnar structure of the present invention is much more excellent in toughness than the conventional columnar structure. As described above, since the Al ₂ O ₃ film having a non-columnar structure has excellent wear resistance and fracture resistance, and its properties do not change even when the film thickness is large, the thickness of the coating layer is increased as a cutting tool. Therefore, the life of the cutting tool can be extended. According to the present invention, non-columnar structure Al
₂ O ₃ or AlON is composed of fine crystal grains as compared with the columnar crystal structure. The average particle diameter of the conventional columnar crystal structure is about 3 to 8 μm, whereas that of the non-columnar crystal structure is 1 μm.
平均 4 μm. Further, in the conventional columnar crystal structure, the growth starting point of the crystal exposed on the surface is almost always at the interface with the substrate. On the other hand, the crystal structure of the present invention is greatly characterized in that a growth starting point of a crystal having a surface exposed exists in the film. As the tool base material used in the present invention, conventionally known ones can be used.For example, Si ₃ N ₄ sintered body, SiC sintered body and cemented carbide can be used. Is most desirable. The cemented carbide used is a hard phase component composed of one or more selected from carbides, nitrides and carbonitrides of metals of Groups 4a, 5a and 6a of the Periodic Table.
The hard phase component is bonded by an iron group metal such as e, Co, Ni or the like, and represents 90 to 95% by weight of the whole. When Al oxide or oxynitride is provided on the surface of such a cemented carbide, the reaction gas, for example, oxygen such as CO ₂ diffuses into the base material when the Al oxide or oxynitride film is formed, and adverse effects are caused. Since there is a possibility that the intermediate layer may be formed of one or more selected from carbides, nitrides, and carbonitrides of metals belonging to groups 4a, 5a, and 6a of the periodic table, a base material and an Al-based compound layer may be formed. It is desirable to intervene between them. In this case, the middle layer is 3
８8 μm, and the entire coating layer has a thickness of 72323 μm.
It is adjusted to a film thickness of μm. In manufacturing the hard film-coated member of the present invention, an oxide or oxynitride of Al is formed by a chemical vapor deposition method. Conventionally, a columnar crystal structure is formed by continuous growth from nucleation to film growth under the same conditions as described above. In the present invention, in the process of growing an Al compound film, a step of generating a nucleus of a new Al compound is repeated once or more,
Prevents crystals from becoming columnar. That is, after nucleation, after growing to a thickness that does not become columnar, film formation is temporarily interrupted,
Introducing HCl and H ₂ O gas to etch 10-30 minutes the product film into the reactor. Thereafter, when initial conditions are set and a film is formed, a new nucleus of the Al compound is generated and a film is formed. By repeating these steps, a film of Al oxide or oxynitride having a desired film thickness is finally obtained. As another method, a method of dispersing a small amount of a compound of the second component such as TiC, TiCN, or TiN on the surface instead of performing etching may be mentioned. That is, after the compound of the second component is generated for a few minutes and generated and dispersed within a range that does not form a film on the surface of the Al compound film, a new nucleus of the Al compound is formed even when the Al compound film is obtained by setting the initial conditions. In addition to the generation, grain growth can be suppressed. Hereinafter, the present invention will be described with reference to the following examples. Example 1 As a base material, ISO P-30 (made of cemented carbide) (model number CNMG43
H ₂ 92% at a temperature 1020 ° C. by a known CDV method using 2), TiCl _{4 4}
% And CH _{4 in} a mixed gas flow of 4%. On the other hand, two kinds of samples were prepared by the following method. An Al ₂ O ₃ film was formed at a reaction temperature of 1000 ° C. in a mixed gas flow of 92% H ₂ , 3% AlCl ₃ , and 5% CO ₂ , and samples having a film thickness of 2, 4, 7, 10, 14 μm were prepared. . When the structure of the Al ₂ O ₃ film of this sample was confirmed with a microscope, it was found to be a columnar structure having an average particle size of 3 to 8 μm. The photomicrograph of the 4 μm sample of the Al ₂ O ₃ film is shown in FIG.
Shown in the figure. Under the same conditions as above, the thickness of the Al ₂ O ₃ film was 2,4,5,10,14,18μ
m sample was prepared. At this time, an Al
Each time the ₂ O ₃ film grows, the film formation is interrupted and H ₂ 70%, HCl 30%
The surface of the Al ₂ O ₃ film was etched for 30 minutes in a mixed gas flow of. When the structure of this sample was confirmed, it was a non-columnar structure having an average particle diameter of 1 to 4 μm. Al ₂ O ₃ film 5μ
The micrograph of the sample m is shown in FIG. Each sample obtained above was subjected to a cutting test under the following conditions. Abrasion test work material FC-25 Speed 150m / min Feed 0.3mm / rev Depth of cut 2mm Time 15min After cutting under the above conditions, the flank wear was measured, and the relationship between the film thickness and flank wear in each sample was measured. This is shown in FIG. Fracture resistance test work material S45C (with 4 grooves of 10mm width) Speed 100m / min Feed 0.3mm / rev Depth of cut 2mm Impact frequency About 500 times After cutting under the above conditions, each sample (20-30 pieces each) )
After cutting, the ratio of chipping (cutting ratio) was determined. FIG. 2 shows the relationship between the film thickness and the defect rate. According to the results of FIGS. 1 and 2, as described above, the coating member of the present invention shows excellent fracture resistance and impact resistance in the range of 4 to 15 μm, and more particularly in the range of 4 to 10 μm. Excellent performance. Example 2 In Example 1, every time an Al ₂ O ₃ film having a thickness of about 2 μm was grown, the film formation was interrupted, and 91% of H ₂ , 5% of TiCl ₄ , and ₄ % of CH ₄ were introduced into a furnace. After generating TiC for a minute, an Al compound film was coated again, and this was repeated to finally provide an 8 μm Al ₂ O ₃ film. The film had a non-columnar structure. The coated member was subjected to the same abrasion test and chipping resistance test as in Example 1. As a result, the flank wear amount was 0.21 mm and the chipping ratio was 25%, indicating excellent performance. Example 3 For the same TiC coated base material as used in Example 1, 1
_{000 ℃ H 2 85%, AlCl} 3 3%, CO 2 5%, Al in N ₂ 10% of the mixed gas stream
After the deposition of approximately 2μm thick performs deposition of oxynitride, H ₂ 70
% And HCl in a mixed gas flow of 30%, the surface was etched for 30 minutes, and the film formation and etching operations were repeated to finally obtain a 6 μm Al oxynitride film. This film had a non-columnar structure having an average particle diameter of 2 μm. When a wear test and a fracture resistance test similar to those in Example 1 were performed on this sample, the flank wear amount was 0.3%.
Excellent cutting performance with a 24% chipping rate of 32%. [Effects of the Invention] As described above in detail, according to the present invention, when Al oxide or oxynitride is provided as a hard film on a base material, the hard film has a crystal structure in which fine crystal grains are aggregated. When compared with the conventional columnar crystal structure, the toughness of the hard film can be significantly improved, and even when coated on a high toughness base material, without impairing the toughness of the base material. The thickness can be increased, and not only the fracture resistance but also the wear resistance can be improved. Therefore, when this hard film-coated member is used as a cutting tool, cutting stability and long life can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the relationship between the thickness of the hard film and the flank wear amount, and FIG. 2 is a diagram showing the relationship between the thickness of the hard film and the defect rate; FIG. 3 is a micrograph (about 3000 times) showing the crystal structure of the hard film in the present invention, and FIG. 4 is a micrograph showing the crystal structure of a conventional hard film.

Claims (1)

(57) [Claims] The thickness of a non-columnar structure Al oxide or oxynitride formed by agglomeration of fine crystal grains on the base material surface is 4 to
A hard film-coated member coated with a 15 μm hard film. 2. Claims wherein the base material is made of a cemented carbide in which one or more of carbides, nitrides, and carbonitrides of metals of Groups 4a, 5a and 6a of the periodic table are combined with an iron group metal. 2. The hard film-coated member according to claim 1.