JPH0196073A - Method for brazing diamond - Google Patents

Abstract

PURPOSE:To increase the brazing strength of diamond to a metal substrate by coating the surface of the diamond with a metal carbide or carbonitride by vapor phase synthesis in a specified temp. range and by brazing the diamond to the substrate with a brazing filler metal. CONSTITUTION:The surface of diamond 5 is coated with a metal carbide or carbonitride 4 by vapor phase synthesis at 350-1000 deg.C. The diamond 5 is then brazed to a holder 7 with a brazing filler metal 6. The bonding strength is increased and the effective volume of the diamond can be increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a diamond brazing method that can be used in the fields of diamond dressers, diamond metal bond grinding wheels, diamond metal bond cutting wheels, diamond single crystal cutting tools, and diamond jewelry. It is about the method.

[Conventional technology]

Sintered body mainly composed of diamond powder and CBN powder,
As a means of brazing diamond single crystals, CBN single crystals, etc. to metal shanks, it is widely practiced to apply plating using a combination of electrolytic or electroless plating with Ni, etc., and to braze the metal shanks through the plating layer. It is being said.

Furthermore, a method is known in which the bonding strength between the diamond and the heat sink is increased by coating the diamond with metal such as titanium or chromium by ion plating, as disclosed in JP-A-60-155600.

[Problem that the invention seeks to solve]

In the conventional method of combining metal plating and brazing, the hardness of the plating layer is not sufficient, resulting in plastic deformation of the plating layer, and the adhesion between the plating layer and the base material interface is weak, causing the material to be brazed to fall off. It was a problem.

Furthermore, in the method disclosed in JP-A-60-155600, since a metal whose surface is easily oxidized, such as chromium or titanium, is used, the adhesive strength with ordinary brazing materials is not so high.

[Failure to solve the problem]

To solve the above problems, instead of conventional metal plating, metal carbide or metal carbonitride, which has high hardness, excellent adhesion to the plated material, and excellent wettability with brazing, was synthesized using a vapor phase synthesis method. It has been found that coating is desirable. These substances include Ti, Zr, Hf, V,
Metal carbides and metal carbonitrides of Nb, Ta, Cr, Mo and W are preferable. Among them, when a Ti compound is used, particularly good results can be obtained in the following respects.

For example, when diamond is coated with TiC or TiCN, the bonding strength between the coating layer and the diamond is high, and the wettability with brazing is improved.

Therefore, the strength of the brazing with the metal substrate is increased.

Furthermore, since these compounds have high hardness, they hardly deform when subjected to force, and therefore the bonding strength is maintained even if subjected to multiple impacts. As a method of coating diamond with metal carbides, carbonitrides, etc., plating is carried out using the CVD method at a temperature of 1000°C or less in order to ensure that the compound spreads over the surface of the base material and to prevent quality deterioration of the diamond base material. The so-called gas-phase synthesis method is the most superior in terms of characteristics.

Furthermore, in order to improve the degree of adhesion between the base material and the plating layer, before forming the plating layer, one layer or a mixture of hydrogen gas, oxygen gas, or a mixture of these gases and argon, nitrogen, etc. Pretreatment is carried out using the so-called ion etching method, in which ions are generated and accelerated by bringing a mixed gas with an inert gas into a discharge state, and collide with the surface of the substrate to form minute defects on the surface. It is desirable to uniformly form submicron irregularities on the surface.

By doing so, the density of nucleation of the carbide or carbonitride of the coating layer on the surface of the substrate increases, and as a result, the adhesion between the coating layer and the substrate improves.

As a means of vapor phase synthesis using the CVD method at temperatures below 1000°C, since the substance is a metal carbide or metal carbonitride, the plasma CVD method, which can easily synthesize the compound at a low temperature below 1000°C, is recommended. It is more desirable to use Further, below 350° C., the bonding strength between the coating layer and diamond decreases.

[Effect]

The effects of the technical means described above will be described below.

■ Effects of vapor phase plating using the CVD method Diamond is generally three-dimensional, and it is necessary to coat the entire surface with a uniform thickness, but the CVD method has advantages in this respect compared to other methods. I am winning. In addition, many diamonds are relatively small in size (the maximum diameter is several 1, the largest is 1
0 mm), and the above-mentioned method, which allows vapor phase treatment by simply arranging them on a jig, is preferable in terms of productivity.

■ Effect of ion etching treatment at the stage before CVD treatment As mentioned above, the key to the formation of a metal carbide or metal carbonitride coating layer by the CVD method is the particle size of the coating layer. Specifically speaking, it is the size of the critical nucleus that stabilizes the initial nucleation. In order to promote the formation of this critical nucleus and increase the nucleation density, it is necessary to form defects such as pit-like depressions on the surface of the base material. This allows the subsequent coating layer to be formed on the diamond with good adhesion.

(2) Effect of Coating Using Plasma CVD When diamond is heated to around 1200° C. in H, gas or vacuum, graphitization progresses and it loses its properties as diamond. Therefore, in order to stably coat diamond with the CVD method in which the reaction is carried out in a reduced pressure hydrogen gas atmosphere, it is a prerequisite that the treatment be performed at a temperature of 1000° C. or lower.

However, with the CVD method, it is difficult to produce a gas phase synthesis reaction of metal carbides and metal carbonitrides at relatively low temperatures below 1000°C, and the plasma CVD method, which enables reactions at lower temperatures, is the main method. It is more suitable for the purpose.

The method of the present invention can be applied to natural diamonds, artificial diamonds, and polycrystalline diamonds, but is particularly effective in fields such as diamond dressers that require high bonding strength.

〔Example〕

The present invention will be described in detail below with reference to Examples.

[Example 1] A diamond dresser was prototyped by treating the diamond surface using a vapor phase synthesis method.

Brazing is done at 700-800℃ in vacuum or cloudy gas.
It was carried out in No carbonized phase was observed on the diamond surface. The brazing strength was 3 to 4 times higher than Ni-plated diamond, which is the conventional method, and no diamond was observed to be missing during actual use.

In the brazing part, in order to compensate for the low adhesion in the conventional method, diamond 1 was reinforced and fixed with a holder 3 through brazing 2 as shown in Fig. 2.

As shown in Fig. 1, by treating the diamond 5 with TiC using a vapor phase synthesis method, the adhesion force to the holder 7 is increased through the brazing 6, and reinforcement by the holder as shown in Fig. 2 is achieved. There is no need for

As a result, the effective volume of available diamond increases,
A 3 to 4 times longer life was achieved.

[Brief explanation of the drawing]

FIG. 1 shows a diamond dresser using the present invention, and FIG. 2 shows a conventional example. In the figure, 1.5: Diamond 2.6: Brazed 3.7: Holder 4: Surface coating layer, j-1

Claims (5)

[Claims] (1) In the method of brazing diamond to a metal substrate, the diamond surface is coated with metal carbide or metal carbonitride by vapor phase synthesis at a temperature of 350°C or higher and 1000°C or lower, and then the metal is coated with metal carbide or metal carbonitride using brazing. A method for brazing diamond, comprising brazing a substrate and the diamond. (2) The diamond brazing method according to claim (1), wherein the metal carbide or metal carbonitride is a Ti carbide or carbonitride. (3) The diamond brazing method according to claim (1), wherein the vapor phase synthesis method is a CVD method. (4) The diamond brazing method according to claim (1), wherein the vapor phase synthesis method is a plasma CVD method. (5) A patent claim characterized in that the diamond is pre-treated by etching using one or both of hydrogen gas and oxygen gas, or a mixed gas containing Ar and N_2 as an inert gas. A diamond brazing method according to item (1).