KR940000279B1 - Cutting tool for making a surface hard alloy and method for forming the same - Google Patents

Abstract

The harden material coated layer is formed on the surface of cemented carbide cutting tool by low pressure chemical depositing method. The coating material includes at least one alloy selected from group of TiCN, TiC, TiN and Al2O3. The chemical depositing method comprises the reaction of the cemented carbide substrate and organic carbon compound at 600-850 deg.C.

Description

Cutting tools with hard surface alloys and their coating methods

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cutting tools requiring wear resistance, heat resistance, and corrosion resistance, and particularly for turning or milling by coating a hard material on a drawaway insert in which cermet or cemented carbide is the basic substrate. The present invention relates to a cutting tool having a surface hard alloy coating layer capable of exhibiting excellent performance as a cutting tool.

Cutting tools commonly used are cermets mainly composed of WC-based cemented carbide and Ti (C) N.

The disadvantage of the WC-based cemented carbide is to receive a tool heat of 500-1100 ℃ during cutting, the hardness is weakened by this high temperature, plastic deformation occurs, the cutting resistance is increased to shorten the life of the tool.

Therefore, in order to improve the fragility in the high temperature hardness, Ti (C) N, which is excellent in high temperature hardness, mainly contains nitrogen during manufacturing, so that a cermet having a fine grain size and increasing hardness has been developed and used a lot. to be.

In addition, as disclosed in Japanese Patent Application Laid-Open No. 2-224532 for the purpose of improving wear resistance, heat resistance, and corrosion resistance of the WC-based cemented carbide, carbides, nitrides, carbonitrides of Ti, Zr, and Hf are formed on the surface of the WC-based cemented carbide. , A single layer of carbonate, carbonitride, Al ₂ O ₃ , or two or more types of layers, using TiCl ₄ as an inorganic compound, and forming a coating layer having a thickness of 0.5-20 mm (500-20000 μ). It is known to do so.

In order to manufacture these coating products, high temperature chemical vapor deposition (HT-CVD), physical vapor deposition (PVD) and the like are employed.

This high temperature evaporation method coat | covers at high temperature of about 1,000 degreeC.

Therefore, the adhesive strength between the coating film foil and the substrate (Sub-strate) due to the diffusion phenomenon has a great advantage, while the tissue deformation occurs due to the high temperature, there is a disadvantage that the structure becomes weak, so that the heat deformation or structure when used as a tool There are some drawbacks such as weakening of the substrate due to change easily.

That is, in the case of the high temperature chemical vapor deposition method, the biggest disadvantage is that the toughness is reduced because the formation of the cermet thin film is made at a high temperature to cause a change in the substrate.

When the coating layer treated by the high temperature chemical vapor deposition was observed with a scanning electron microscope, it can be seen that it has a crystalline structure.

Therefore, in this crystal boundary, the fragility of the tissue destroyed by the cracks is obtained.

On the other hand, physical vapor deposition is a method of coating titanium carbide, titanium nitride, or titanium carbonitride at a low temperature of 500 ° C. or lower. Although thermal deformation and tissue change occur less than high temperature chemical vapor deposition, There was a drawback of poor adhesive strength.

Therefore, the use on both of these uses is limited to turning.

An object of the present invention is to cut the adhesion between the substrate and the coating film, which is a disadvantage of the physical vapor deposition method, and to reduce the toughness of the excessive substrate, which is a disadvantage of the high temperature chemical vapor deposition, and to maintain the toughness of the substrate. To provide a tool.

Another object of the present invention is to provide a cutting tool in which a surface hard alloy is formed to have a strong bonding force between a substrate and a coating material.

The present invention is one or two or more selected from TiCN, Tic, TicN and Al ₂ O ₃ by a low temperature chemical vapor deposition method made at 600-850 ℃ on the surface of the cemented carbide or nitrogen-containing cermet to achieve the above object A low temperature treatment coating layer is formed.

The low temperature chemical vapor deposition method employed in the present invention is the same as the high temperature chemical vapor deposition method, but deposits carbonitride (TiCN) on a substrate at a temperature of about 500 to 900 ° C. using an organic carbonaceous component of CH 3 CN as a reaction medium. This is how you do it.

Its reaction takes place as in the following reaction formula.

[Scheme]

As shown in this scheme, CH ₃ CN, an organic compound, is added to the used material added in the coating process to act as a CN group source of the coating material.

It is preferable that the thickness of the said coating thin film layer is 1-15 micrometers, More preferably, it is 3-10 micrometers.

In addition, in the structure of a coating thin film, the thin film thickness of TiCN is 1 micrometer or more in a single layer or a composite layer, and it must occupy 70% or more especially in a composite layer.

And the thickness of the whole thin film should be 15 micrometers or less.

Therefore, as a result of the conventional art, when the thick coating layer of 500 μm or more is formed, the life degradation phenomenon, that is, the impact of the film quality of the ceramic film during the cutting process cannot be transmitted to the substrate, and when the coating layer is broken, microcracks are generated at the same time. It is possible to prevent the phenomenon that the life of the tool decreases as a cause.

The surface-coated hard alloy material of the present invention exhibits better performance than that of the physical vapor deposition method in the degree of adhesion between the coating thin film and the substrate, and can prevent the deterioration of toughness by the high temperature chemical vapor deposition method to the maximum. It is possible to obtain a cutting tool that is more abrasion-resistant than a mat and wholly superior in toughness to products by high temperature chemical vapor deposition.

This effect of the present invention can be clearly seen as the amount of change in the mean free stroke of the magnetic force on the metal by measuring the coercive force.

In the present invention, the micro-Vickers hardness was measured in order to measure the wear resistance which indicates the life of the tool during cutting. The hardness was higher than that of the high temperature chemical vapor deposition method, and the wear resistance was not only related to the hardness of the film but also to the internal compressive stress. Considering that there is at least the degree of adhesion between the thin film and the base material is the same as in the high temperature chemical vapor deposition method.

Although the fracture surface structure of the thin film by the low temperature chemical vapor deposition method of the present invention shows a typical columnar structure, the structure of the fracture surface of the product by the high temperature chemical vapor deposition method and the physical vapor deposition method is amorphous.

Hereinafter, embodiments of the present invention will be described.

EXAMPLE

The cermet powder of ISO standard P10-P20 was prepared by a conventional manufacturing method in a composition of 150 wt% WC, 35 wt% TiC, 15 wt% TiN, 10 wt% TaC, and 25 wt%.

Using this sample, the cutting tool according to the present invention, the cutting tool according to the high temperature chemical vapor deposition method, and the cutting tool according to the physical vapor deposition method were prepared, and their characteristics were compared and measured, and the results are shown in Tables 1 and 2.

TABLE 1

TABLE 2

As can be seen in Tables 1 and 2 above, in the magnetic force measurement to determine the magnetic properties of the sample, CERMET ≧ PVD = Invention (MT-CVD)> HT-CVD.

In addition, the drag force values were in the order of CERMET> PVD> MT-CVD> HT-CVD.

This indicates the effect of the present invention (MT-CVD) in toughness, and the lower the formation temperature of the thin film, the less the change in the structure of the substrate.

In addition, in order to determine the toughness of the tool, IMSERT (Model No .: SNGN120408) was manufactured and tested in the same process as in the above conditions.

TABLE 3

※ Example ○: Damage for more than 20 seconds (1 point)

(Triangle | delta): Damage | damage in more than 2 second and less than 20 second (0.5 point)

×: damage within 2 seconds (0 point)

As can be seen in Table 3, the present invention was shown to be excellent in toughness compared to the high temperature chemical vapor deposition method.

This result is the same as in Tables 1 and 2 above.

On the other hand, in order to determine the wear resistance of the tool, the insert (model number: SNGN120408) manufactured and tested in the same process as the above conditions are shown in Tables 4 and 5 below.

TABLE 4

TABLE 5

The test conditions in Table 4 above are as follows.

Holder: FNI1R-44A

Insert: SNGN120408

Work: SCM440 (Hs530)

V = 220 m / min, f = 0.37 mm / rev, d = 1.5 mm

As shown in Table 4 above it can be seen that the present invention is also excellent in wear resistance.

Table 5 shows the results of testing the abrasion resistance under the same conditions with only the cutting speed of 250 m / min under the conditions of Table 4 described above.

The test conditions in Table 5 above are as follows.

Holder: FNI1R-44A

Insert: SNGN120408

Work: SCM440 (Hs530)

V = 250 m / min, f = 0.37 mm / rev, d = 1.5 mm

As shown in Table 5 above, it can be seen that the cutting speed of 250 m / min exhibits the same performance as that of the high temperature chemical vapor deposition method.

In addition, when the crystal structure of the coating layer formed by this low temperature chemical vapor deposition method is irradiated with an X-ray diffractometer, it has almost the same height as amorphous, and the fracture surface has a columnar structure, resulting in a dense structure. It can be seen that the toughness is excellent because there is no crystal boundary.

As described above, a high temperature at which one or two or more of TiC, TiCN, and Al ₂ O ₃ is coated by high temperature chemical vapor deposition on the surface of which the low temperature treatment coating layer by low temperature chemical vapor deposition is primarily formed on the surface of the substrate. It is also possible to form a plurality of treatment coating layers.

In this case, the total coating thickness is effective to be carried out within a range not exceeding 15㎛, and the high temperature chemical vapor deposition method is the same as the coating treatment at a high temperature of about 1,000 ℃ as in the prior art.

Therefore, the lowering of the toughness of the substrate due to the characteristics of the high temperature coating layer is prevented as a result of the formation of the low temperature coating layer therebetween.

As described above, according to the present invention, the adhesiveness between the substrate and the coating thin film, which is a disadvantage of the physical vapor deposition method, and the toughness of the excessive substrate, which is a disadvantage of the high temperature chemical vapor deposition method, can be eliminated and the toughness of the interposition can be maintained as it is, so that the wear resistance, heat resistance and corrosion resistance It can provide excellent tools.

In addition, it is well suited for applications in which the mechanical impact is rapidly transmitted to the substrate to suppress the film quality, that is, the coating layer, in turning, as well as in a variety of machine tools, particularly in applications with repeated intermittent operations such as milling. It is a useful invention such as can be.

Claims (7)

In the case where at least one hard coating layer is formed by a chemical treatment method of adding a reactant to the surface of the cemented carbide substrate, the chemical treatment method is a low-temperature chemical vapor deposition method performed at 600 to 850 ° C. And a low temperature treatment layer selected from at least one of hard coating materials of Al ₂ O ₃ . The cutting tool according to claim 1, wherein the thin film of TiCN is formed to have a thickness of at least 1 to 15 µm in a single layer or a composite layer. The cutting tool according to claim 1, wherein the low-temperature treated coating layer has a thickness of 1 to 15 µm in the total coating layer in the composite layer treated with two or more kinds. The cutting tool according to claim 1, wherein the reaction medium comprises an organic carbonaceous component composed of CH ₃ CN. The cutting tool according to claim 1, wherein the base material comprises a cermet in which TiCN is mainly contained in a WC-based cemented carbide. In the case where at least one hard coating layer is formed by a chemical treatment method of adding a reactant to the surface of the cemented carbide substrate, the chemical treatment method is an organic reaction of CH ₃ CN as a reaction medium at a temperature between 600 and 850 ° C. A method of coating a cutting tool having a surface hard alloy formed thereon, wherein at least one of TiCN, TiC, TiN, and Al ₂ O ₃ is selected and coated by low temperature chemical vapor deposition to react carbonaceous components. The method of claim 6, wherein the base material comprises a cermet in which TiCN is mainly contained in a WC-based cemented carbide.