JPS595665B2 - Surface-coated cemented carbide parts and their manufacturing method - Google Patents

Description

[Detailed description of the invention] WC or/and Ti, Zr, , Hf, , V, Nb
The base material is a cemented carbide in which ferrous metal is combined with a mixture or solid solution of one or more of carbides and/or carbonitrides of Ta, Cr, Mo, and W, and the surface is coated with Ti,
The so-called coated chips, which are coated with carbides and carbonitrides of Zr and Hf to a thickness of several microns, have both the toughness of the base material and the wear resistance of the surface, making them superior to conventional cemented carbides as cutting tools. It is a widely known fact that it has excellent performance.

An object of the present invention is to stably provide such a coated chip with further improved characteristics.

Up until now, improvements in coating chips have been mainly aimed at multiplexing the coating layer or changing the type of coating layer, but although these improve wear resistance, they do not solve the problem of toughness. do not have.

The greatest feature of the present invention is that it uses an alloy containing free carbon, which until now has been considered to be a defective cemented carbide.
The present invention is based on the discovery that the toughness of coated chips can be greatly improved.

The innermost layer in contact with the cemented carbide is Ti, Zr, Hf, V, and Nb.
, Ta, Cr, Mo, and/or carbides and/or carbonitrides of w are suitable, and Ti will be described below as an example.

To coat cemented carbide with Ti carbide or carbonitride, Ti halide (-4, titanium tetrachloride), hydrocarbon (generally methane), nitrogen, and hydrogen gas are mixed in a predetermined ratio. A so-called chemical vapor deposition method is used in which titanium carbide and titanium carbonitride are precipitated from gas at a high temperature of around 1000° C. to coat the cemented carbide. Titanium carbonitride is similar to titanium carbide, so titanium carbide will be described below as an example.

The reaction process of the precipitation reaction of titanium carbide by the chemical vapor deposition method described above is very complicated, but it can be easily explained by two steps: generation of free titanium according to the following equation 1, and carbonization of free titanium according to the following equation 2. It will be done. The carbonization of the free titanium in Type 2 is carried out by the free carbon produced by the decomposition of hydrocarbons in the gas mixture and the carbon supplied by the cemented carbide matrix.

When the concentration of hydrocarbons in the mixed gas is low, most of the hydrocarbons required to generate titanium carbide are supplied by diffusion of carbon in the cemented carbide matrix, and a brittle decarburized layer called the η phase forms immediately below the titanium carbide coating layer. is formed, which significantly impairs the toughness of the coating chip. On the other hand, when the hydrocarbon concentration in the mixed gas is increased, most of the carbon necessary for titanium carbide production is supplied from the gas phase.
Although it is possible to make a coating chip in which the above η phase is almost absent, when the hydrocarbon concentration exceeds a certain level, free carbon is generated in the coating film, which also significantly reduces the toughness and wear resistance of the coating chip. thwart. In this way, in a coating chip in which most of the carbon required to generate titanium carbide is supplied from the gas phase, the coated Ti
Peeling tends to occur between the C layer and the cemented carbide base material, which also significantly impedes the wear resistance of the coating chip.
Therefore, the inventor considered the following in order to solve both the occurrence of the η phase and the flaking of the coating layer described above.
In order to prevent peeling of the coating layer, while maintaining sufficient carbon supply through diffusion from the cemented carbide base material, to prevent the generation of η phase, carbon is chemically added to the cemented carbide base material in the form of free carbon. It was thought that it would be sufficient to accumulate the TiC before coating it by vapor deposition.

It is generally known that the presence of free carbon in cemented carbide significantly impairs the wear resistance, but in the case of the present invention, since the wear resistance largely depends on the surface coating layer, free carbon is not included. However, we thought that the wear resistance would not decrease much even if a cemented carbide base material was used. Based on the above idea, when a cemented carbide base material containing free carbon is coated with titanium carbide by chemical evaporation, no η phase is present.

Moreover, it has become possible to create a coating chip in which peeling of the coating layer hardly occurs during cutting. Furthermore, free carbon in the cemented carbide base material, which contributes to the formation of titanium carbide, is approximately 50
Since it was found that the depth was up to μ, it was found that it was sufficient that the free carbon was precipitated to a depth greater than that.

In addition, as a limit on the amount of free carbon, 0.01 to 0.50% by weight
However, if it is less than 0.01% by weight, no effect will be observed, and if it is 0.50% by weight, the abrasion resistance after coating will be impaired.

Among these, the most effective range is 0.05 to 0.35.
Weight%. The above are the advantages of single layer coating, but the innermost layer is A, . Similar effects can be expected from multi-coated chips in which various nitrides, oxides, carbides and/or mixtures or compounds thereof are coated in one or more layers in the case of vla carbides or carbonitrides. Furthermore, when coating with an oxide in one layer or in multiple layers, the following effects can be expected. For example, oxides belonging to groups ~ ~ of the periodic table that are inert to ferrous metals up to near their melting point, such as magnesium oxide, beryllium oxide, thorium oxide, hafnium oxide, titanium oxide, zirconium oxide, chromium oxide, Wear resistance is greatly improved when the cemented carbide surface is coated with aluminum or a mixture, compound, or solid solution of aluminum with at least one of these oxides, or a ternary solid solution of aluminum oxide, calcium oxide, and silicon oxide, such as gelenite. I know that I will.

However, these coatings have the disadvantage of causing oxygen to diffuse into the cemented carbide base material, thereby making the base material brittle. To prevent this, A. There is a technique in which carbides, nitrides, carbonitrides, and/or compounds containing oxygen of groups Va and A are sandwiched between a base material and an oxide layer as an intermediate layer and used as a diffusion barrier. for example,
The outermost layer is coated with aluminum oxide, the middle layer is coated with titanium oxide, and the innermost layer is coated with the above carbide. By the way, carbides, nitrides, carbonitrides, and/or their oxygen-containing compounds serve as barriers, and the higher the ratio of nonmetallic components to metallic components, the more effectively they act as a barrier to oxygen diffusion. However, when a base material containing free carbon is used, the value of the above ratio becomes extremely high, suppressing the diffusion of oxygen into the base material, and making it possible to obtain cutting chips with extremely high toughness.

In addition, when coating with an oxide mainly composed of aluminum oxide or zirconium oxide, the innermost layer in contact with the cemented carbide is coated with a carbide or carbonitride such as titanium carbide, and the inner layer in contact with the oxide layer is coated with oxygen. titanium carbide containing
When nitrides and carbonitrides are sandwiched, the oxygen potential of the latter layer increases, and the inflow of oxygen due to decomposition of the oxide layer decreases or disappears, making it even more effective.
Examples will be described below.

Example 1 A cemented carbide base material (model number SNU4) containing 0.08% by weight of free carbon with exactly the same composition as commercially available 1S0-P3O cemented carbide was used.
32) was heated to 1000°C in a reaction vessel made of Inconel (trade name of nickel base alloy manufactured by Inco), and H286%T was heated.
A mixed gas of 47% iCl and 47% CH was flowed at 40 t0rr to coat titanium carbide to a predetermined thickness.

After cooling, the chip was taken out, cut, and examined. It was found that the chip was coated with 5 μm of titanium carbide, and no η phase was present.
A cutting test was conducted under the following conditions using a SO-P3O cemented carbide chip (model number 432.) coated with 5μTiC under exactly the same conditions (hereinafter referred to as a normal TiC-coated chip). . With the chip of the present invention, blank wear is 0.2311! Even with a normal TiC coated chip, there was almost no difference between the blank wear and the wear of 0.2211.

When cutting was performed 100 times under the above conditions, the chip of the present invention had a breakage rate of 0%, while the chip of the present invention had a breakage rate of 33%, demonstrating the good toughness of the chip of the present invention. Ta.

Example 2 ISOP- containing 0.08"% free carbon as in Example 1
30 cemented carbide (model number TNMG432ENU), and commercially available free carbon-free 1S0P-30 cemented carbide (model number T
NMG432ENU) was coated with 5 μm of titanium carbide under exactly the same conditions as in Example 1, and a cutting test was conducted under the following conditions.

When cutting with the chip of the present invention, 112 pieces could be machined, whereas with the conventional titanium carbide coated chip, only 65 pieces could be machined due to peeling off of the coating layer. When cutting with the chip of the present invention, 142↓Toge 1 Ya; Naruhino ▲^1A. Ih Todoroh No C Maman A Mountain Parts I could only process 98 pieces with the coated chips.

Example 3 Same as Example 1, ISO-P3O cemented carbide base material containing 0.08% free carbon (model number TNMG432EN
U) was heated to 950°C in an Inconel reaction vessel, and H2
A mixed gas of 8O%, ZrCl45%, CH45%, and N2lO% was flowed at 80t0rr to coat the zirconium carbonitride.

After cooling, the chip was taken out, cut and examined, and it was found that it was coated with 5μ of zirconium carbonitride and no η phase was present. When cutting was performed using this chip under the conditions 2 of Example 2, 158 pieces could be cut. Example 4
Two types of cemented carbide base materials (model number SNU432), Alloy A with a free carbon content of O and Alloy B with a free carbon content of 0.15%, each having a commercially available 1S0-P3O cemented carbide composition, were mixed with Inconel (nickel base alloy trade name of Inco Co., Ltd.). ) in a reaction vessel made of
It was heated to 0.degree. C., and a mixed gas of 86% H2, 7% TiCl, and 47% CH was flowed at 40T0rr, and 5μ of titanium carbide was coated.

Following this, H28O%, CO23%, CO12%
and a gas having a composition of 35% AlCl at 20T0r.
Both samples produced a N2O3 coating of about 1.5 microns. When these chips were cut under cutting conditions 1 of Example 1, chip A showed 0.0 blank wear.
Even for 217 nm chip B, there was almost no difference in blank wear of 0.20 u.

Next, when cutting was performed 100 times under cutting conditions 2 of Example 1, the chip A had a breakage rate of 67%, while the chip B had a breakage rate of 5%, demonstrating the good toughness of the chip of the present invention. .

Example 5 Titanium carbide was applied to two types of commercially available 1S0-P3O cemented carbide alloys, Alloy C with a free carbon content of 0% by weight and Alloy D with a free carbon content of 0.30% by weight, in substantially the same manner as in Example 1. 4μ, on which 1μ of titanium nitride was coated.

Using these chips, cut S55C forged material at a cutting speed of 1
40m/ml! L, feed 0.40m7! When cut at L/Rev and depth of cut of 2 to 5, the average life of D was 1.5 times longer than C. Example 6 T was prepared in the same manner as in Example 4 using the same base material as in Example 4.
A chip was prepared by coating 3μ of iC and then 1μ of ZrO2.

In the case of alloys containing no free carbon, a brittle η phase was formed between the lower layer and the base metal, but no η phase was observed in the base metal containing free carbon.

Example 7 Using the same base material as in Example 2, T was prepared in the same manner as in Example 1.
On top of the iC3μ coating, 2μ of gelenite (calcium oxide aluminum monoxide silicon monoxide compound) was coated.

In the base metal containing free carbon, there was no formation of a different phase between the lower layer and the base metal, but in the alloy without free carbon, the formation of a brittle layer was observed.

[Brief explanation of the drawing]

FIG. 1 shows the cross-sectional shape of a workpiece under cutting conditions 2 in Example 1.

Claims (1)

[Claims] 1 Covered in one or more layers with one or more of oxides, carbides, nitrides and/or mixtures and compounds thereof, and the innermost layer in contact with the cemented carbide is IVa.
, Va, group VIa carbide or/and carbonitride 1
In a method for manufacturing cemented carbide parts made of one or more species,
As a base material on which the coating layer is formed, the coating layer is almost uniformly coated with 0.0
A method for manufacturing a surface-coated cemented carbide component, characterized in that a cemented carbide containing 1 to 0.5% by weight of free carbon is used.