JPH0133308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to abrasive objects, particularly abrasive compacts.

Abrasive compacts are already known in the art and include abrasive particles, in particular particles of diamond or cubic boron nitride (hereinafter referred to as cubic boron nitride), preferably in a suitable bonding matrix;
It usually consists of a mass of metal bound together into a hard nodule. The abrasive particle content of the compact is at least 50% by volume, usually at least 70% by volume. Suitable bonding materials include, for example, cobalt, iron, nickel, platinum,
Titanium, chromium, tantalum and these metals
It is a species or an alloy containing two or more species.

When the abrasive particles of the compact are diamond or cubic boron nitride, the compact is produced under temperature and pressure conditions in which the abrasive particles are crystallographically stable.
Such conditions are well known in the art. Preferably, the bonding matrix is capable of dissolving the abrasive particles, at least to a limited extent, when applied. The use of such bonding matrices results in some degree of intergrowth between the abrasive particles during compact manufacture.

metal or cemented tungsten carbide
The abrasive compact is bonded to a suitable support, which may be tungsten carbide, and then used for abrasive operations such as cutting and grinding. Bonding of the abrasive compact to the support can be achieved by a low temperature braze. However, such brazing is not very effective. Another method is titanium hydride/
It has also been proposed to use a soldering method, but the conditions of this method inevitably lead to deterioration of the abrasive particles in the compact.

As an alternative to brazing, a diamond or cubic boron nitride compact can be bonded to a sintered tungsten carbide support by infiltrating the bonding metal from the sintered tungsten carbide support into the diamond or cubic boron nitride layer during the manufacture of the compact. It has been proposed to create an in situ direct bond between

The present invention comprises an abrasive molded body bonded to a metal layer having a thickness of less than 0.5 mm on at least one surface of the abrasive molded body, and this metal layer is bonded to a sintered carbide alloy support. is a hard nodular combination of diamond or cubic boron nitride particles, or a mixture thereof, present in an amount of at least 70% by volume, and a bonding matrix, the bonding matrix being a solvent for the abrasive particles used. and in the case of diamond is cobalt, nickel, iron or alloys thereof, the metal of said metal layer being selected from the group consisting of titanium, tantalum and high temperature brazing alloys containing such metals. It is a thing,
The present invention relates to an abrasive object characterized in that the molded article contains almost no deteriorated abrasive particles.

The abrasive object of the present invention forms a bond between the compact and the support that is highly effective and has a strength greater than that obtained by the use of low temperature braze alone. The molded body can have various shapes, and a metal layer is bonded to the surface of the molded body that is bonded to the support. The shaped bodies are often in the form of circular segments, in which case it is common for the metal layer to be bonded to one of the major planar surfaces of the shaped body.

Metal layers include both pure metals and alloys. An effective bond between the metal layer and the compact is achieved if the metal can wet the abrasive compact, i.e. the metal can wet the abrasive particles of the compact, or the metal can wet the abrasive particles of the compact. This is because it can wet the bonding base material of the molded body or form an alloy with the bonding base material.

Particularly preferred metals are titanium and titanium alloys such as copper/titanium alloys and copper/tin/titanium alloys.

The metal layer is generally less than 0.5 mm thick.

The abrasive object of the present invention is also characterized in that the molded object contains almost no degraded abrasive particles. This means that the compact contains almost no graphite derived from deterioration of diamond and hexagonal boron nitride derived from deterioration of cubic boron nitride. In order to bond the metal layer to the molded body, it is important to reliably suppress such deterioration of the molded body.

The abrasive particles contained in the compact are diamond,
cubic boron nitride or a mixture thereof. The binding matrix acts as a solvent for the abrasive particles. When using such a bonding matrix and using temperature and pressure conditions during the manufacture of the abrasive object at which the abrasive particles are crystallographically stable, intergrowth can occur between the abrasive particles. Diamond solvents are well known in the industry and include cobalt, nickel,
It includes iron and alloys containing one or more of these metals. Cubic boron nitride solvents are also well-liked in the art and include aluminum, lead, tin, magnesium, lithium, and alloys containing one or more of these metals.

The abrasive object of the present invention forms a mixture of abrasive particles and a powdered bonding matrix, and the mixture includes titanium,
a layer of a metal selected from the group consisting of tantalum and high temperature braze alloys containing such metals, and then a sintered carbide alloy support or a powder mixture capable of forming such a support is applied to said metal. contacting the layer and then applying a high temperature and pressure to the entire body within the crystallographically stable range of the abrasive particles and suitable to form a compact of the mixture of the abrasive particles and the bonding matrix. It can be manufactured by applying certain conditions.

As mentioned above, the crystallographic stability conditions for diamond and cubic boron nitride are well known in the art and are illustrated in FIG. The stability region of diamond is above line A, and the stability region of cubic boron nitride is above line B. The metal of the metal layer can be in the form of a powder or a thin foil. The thickness of the powder layer or foil is generally less than 0.5 mm.

In the case of a sintered carbide alloy support substrate, such as a sintered tungsten carbide support substrate, the formed substrate or powder mixture capable of forming the substrate is brought into contact with the metal layer and then the entire By applying the above-mentioned temperature and pressure conditions to the molded body, the formation of the molded body, the bonding of the metal layer to its surface and the bonding of the support substrate to this metal layer are simultaneously achieved, and the bonding between the molded body and the metal and the metal A very effective bond is created between the carrier substrate and the carrier substrate, and the carrier substrate can be bonded to the abrasive compact in situ. The main advantages of the present invention when compared to the above-described conventional methods of directly bonding diamond or cubic boron nitride-containing abrasive compacts to a sintered carbide alloy support in situ are: (1) In the case of direct in-situ bonding, mismatch stress (mis-
Match stress), that is, stress due to the difference in coefficient of thermal expansion between the abrasive compact and the support, is generated, but in the abrasive object of the present invention, the above-mentioned Is there a layer of high temperature braze metal that can deform to accommodate the stress during bonding of the abrasive compact to the support, thereby avoiding the occurrence of mismatch stresses? , or at least significantly smaller. Also (2)
The metal bonding layer in the abrasive bodies of the present invention substantially inhibits the penetration of carbide sintering bond metals, such as cobalt, from the sintered carbide alloy support into the abrasive compact when bonded directly in situ. It can effectively prevent the loss of bonded metal in the sintered carbide support as it acts as a barrier to prevent A quantity of a bonding matrix such as cobalt can be incorporated into the abrasive compact. 1st
The figure shows an example of a molded body bonded to a tungsten carbide base material. In FIG. 1, the compact is indicated at 14, the metal layer at 16, and the tungsten carbide substrate at 18.
Generally, the tungsten carbide substrate has a significantly larger volume than the compact.

Next, the present invention will be explained with reference to examples.

Example 1 A tungsten carbide base material was coated with a thin metallic titanium layer (thickness:
10 μm) and placed in a reaction capsule of a conventional high temperature/pressure apparatus in contact with a mixture of powdered cobalt and diamond particles on this titanium layer. 20% by volume of this mixture is powdered cobalt and 80% by volume
was a diamond. The capsule was placed in the reaction zone of a conventional high temperature/pressure device, and the pressure was increased to approximately 55 kbar and the temperature to approximately 1600°C.
These temperature and pressure conditions were then maintained for a sufficient time to form a compact from the diamond/cobalt mixture. The temperature and pressure conditions were then released. An abrasive object consisting of a diamond compact bonded to a tungsten carbide substrate by a thin layer of titanium was recovered from the reaction capsule. The molded body was firmly bonded to the base material. The abrasive object was a disk that was cut into segments of the type shown in FIG. 1 using standard cutting techniques.

In implementing the present invention, the following terms can be set as conditions for implementation.

(1) The metal of the metal layer is a high temperature brazing alloy, and the high temperature brazing alloy is a copper/titanium alloy or a copper/titanium alloy.
An abrasive object according to claim 1, which is a tin/titanium alloy.

(2) An abrasive object according to claim 1 and the preceding claim, in which the metal layer is in the form of a circular segment, which is connected to one main flat surface of the shaped body.

(3) The abrasive object described in claim 1 and each of the preceding claims, wherein the support is a sintered tungsten carbide base material.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an example of an abrasive object of the present invention;
FIG. 2 is a graph showing the relationship between pressure and temperature, which indicates the crystallographically stable conditions for diamond and cubic boron nitride. 14... Molded body, 16... Metal layer, 18... Tungsten carbide base material, A, B... Wire.

Claims (1)

[Scope of Claims] 1. An abrasive molded body bonded to a metal layer having a thickness of less than 0.5 mm on at least one surface thereof, and this metal layer bonded to a sintered carbide alloy support, The compact is made by bonding diamond or cubic boron nitride particles or a mixture thereof present in an amount of at least 70% by volume to a bonding matrix in the form of a hard nodule. an abrasive object which is the solvent for the particles and is cobalt, nickel, iron or an alloy thereof in the case of diamond, the metal of said metal layer being from the group consisting of titanium, tantalum and high temperature brazing alloys containing such metals; 1. An abrasive object, characterized in that the molded object contains almost no degraded abrasive particles.