Procedure for surface of diamond grains roughing

IPC classes for russian patent Procedure for surface of diamond grains roughing (RU 2429195):

C30B33/02 - Heat treatment (C30B0033040000, C30B0033060000 take precedence);;

C30B29/04 - Diamond

C09K3/14 - Anti-slip materials; Abrasives

C01B31/06 - Diamond

B24D3/10 - for porous or cellular structure, e.g. for use with diamonds as abrasives

Another patents in same IPC classes:

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Present invention relates to chemical engineering, and to high-pressure technology of making diamonds, particularly for growing large crystals, the process of which is long. The high-pressure apparatus has a multiple-punch unit, which is enclosed in a sealed elastic casing 6. In the first version the multiple-punch unit is fitted on a sealed hollow platform 1, which has at least two sealed cavities 10, at least one of which is linked through a valve with the external environment for filling with water when submerged. In the second cavity there is a motor 11, with a pump for pumping water from the first sealed cavity when raising the apparatus. In the second version the sealed cavities can be made in the sealed hollow platform and in one of the punches. In the third version the sealed cavities can be made in at least two punches of the multiple-punch unit.

Abrasive material / 2428299

Invention relates to abrasive industry, particularly, to production of abrasive grains, grinding and micro powders with coat used in making various tools as well as solo product. Proposed material comprises material particles with their surface coated discontinuous with nano coat made up of dispersed lubing agent in amount of 0.01 - 5.00 wt % of unprocessed material bulk. Said dispersed coat consists of iron, silicon and aluminium oxyphosphates structurally bonded with material particles surface phosphorus atomic groups with amount phosphorus compounds in total composition of coat making 0.5 - 1.5 wt %, while that of finely dispersed iron, silicon and aluminium makes 2 to 6 wt %.

FIELD: machine building.

SUBSTANCE: procedure for surface of diamond grains roughing consists in mixing diamond grains with metal powder and in heating obtained mixture to temperature of 800-1100°C in vacuum as high, as 10^-2-10^-4 mm. As metal powders there are taken powders of iron, nickel, cobalt, manganese, chromium, their alloys or mixtures. Powders not inter-reacting with diamond grains at heating can be added to the mixture.

EFFECT: fabrication of diamond grains with optimal amount of recesses, possessing specified geometric parametres; reduced losses of diamond material and maintaining strength characteristics of grains.

4 cl, 1 dwg

The invention relates to the field of processing of diamond grains, more specifically, to obtain the roughness on the surface of the diamond grains. Such grains can be used for the manufacture of diamond tools, such as grinding wheels, ruling the tool, the tool for drilling equipment, instrumentation, etc.

It is known that the performance of the diamond tool largely depends on the strength retention of the diamond grains bonded in the working process of the tool. In the manufacture of diamond tools for the organic binding are mainly used nizkoplotnye diamond grains, such as AC2, AC4 and IS shaped in the form of aggregates, splices, fragments. Such grains have developed surface. Thanks to development of the surface they are well kept ligament. Tools on metal cords, manufactured by the method of galvanothermy or electrotype or by powder metallurgy methods, soldering, etc. and intended, for example, to process difficult materials with a large material removal, use high diamond grains constituting whole crystals, fragments of crystals, aggregates, i.e. crystals, which are mainly planar or non-planar surface. Such grains have poor adhesion with the binder and the working process of the tool is rolled before as they are completely worn out. To improve the strength retention of the diamond grains in such instruments or take a bunch of forming an adhesive bond with the diamond grains or on the surface of the grains applied metal coating, which also forms an adhesive contact with the surface of the diamond grains and a binder metal bond. These methods improve retention of the diamond grains together isn't always possible. For example, in the manufacture of tools in the galvanic bunch they are unacceptable, since the consolidation of the diamond grains on the surface of the body is only due to the mechanical forces of the clutch, and the use of metallic grains causes dentatoalatum on the surface of the tool. Another way to improve the bonding of the diamond grains bonded is applied to the smooth surface of the diamond grains roughness, each representing a different form of grooves, holes, etc. In the production of the binder falls within these grooves and more securely holds the grains together.

A method of obtaining the roughness on the surface of the diamond grains, wherein the diamond grains is etched by keeping them in molten nitrate - potassium nitrate at a temperature of about 700°C. In the etching on the surface of the diamond see is to appear recesses and grooves, who in the manufacture of the tool are filled with a material ligaments, firmly holding the grain in the process tool (German patent No. 1108641, EV, 1957, U.S. patent No. 5349342, CL 51-298, 1968). The disadvantage of this method is that when processed by nitrate addition to the formation of grooves, etching is not only the surface of diamond grains, and thus more intensively travliata sharp cutting edges and corners of the crystal, which leads to significant weight loss of the diamond material and a sharp decrease in the strength of the grain as a whole. This is especially true for synthetic diamonds.

The closest to the proposed solution is the method of obtaining the roughness on the surface of the diamond grains, as described in the application Germany No. 3625743, CL SW 31/06, 1986). The method consists in the fact that the diamond powders are mixed with metal powders, the mixture is placed in a hydrogen or hydrogen-containing environment, heated to 700-900°C and maintained for some time. As metal powders take iron, cobalt, Nickel, a mixture or alloy. When heated diamond carbon diffuses into the metal particles, which touches the surface of the grain, and the hydrogen reacts with the dissolved solid metal carbon with formation of gaseous methane. The disadvantage of this method is that the process-the Oia diamond material from the surface of the diamond grains in the hydrogen or hydrogen-containing environment is continuous, depending on partial pressure and humidity H₂and is therefore difficult to control. As a result, the surface of diamond grains can be formed too large depressions and accordingly will be a large loss of the diamond material and, therefore, a strong destruction of the diamond crystal. Furthermore, the method does not provide optimum number of grooves on the surface of diamond grains, and it is also associated with loss of strength of the crystal and unfounded the loss of the diamond material. In addition, a hydrogen environment at carrying out various processes is explosive, and requires continuous monitoring.

The technical challenge is to simplify the method of obtaining the roughness on the surface of the diamond grains, the possibility of obtaining diamond grains with an optimum number of grooves on the surface of the grain and the optimal geometric parameters of these recesses, resulting in the loss of the diamond material and maintaining the strength characteristics of the beans.

The technical result is achieved in that in the method of obtaining the roughness on the surface of the diamond grains, including mixing of diamond grains with a metal powder, heating the mixture and separation of the diamond grains from metal powders, heating the mixture p is avodat in vacuum at a temperature of 800-1100°C.

As metal powders take the powders of iron, Nickel, cobalt, manganese, chromium, and their alloys or mixtures.

For the Department of the diamond grains from metal powders after heat treatment of diamond grains is exposed to acid.

To regulate on the surface of the diamond grains in the number of recesses (etching pits) in a mixture of diamond grains and the metal powders are additionally injected powders which, when heated, it does not interact with the diamond grains. As such powders can be used, for example, powders of oxides, carbides, nitrides, silicides, etc.

In the pictures (see figure 1) shows the surface topography of diamond grains after heating it in the presence of metal powder in a vacuum.

The method is as follows.

Diamond grains are mixed with a metal powder, which take the powders of iron, Nickel, cobalt, manganese and their alloys, or a mixture. These metal powders in the presence of the diamond to form a solid solution and carbide compounds at relatively low temperatures of 800-1100°C. the Amount of the metal powder should be such that all diamond grains were surrounded them. The device creates a vacuum and heat the mixture to a temperature of 800-1100°C. the magnitude of the vacuum is 10^-2-10^-4mm R is St The dwell time at temperature is 0.5-1.5 hours. When heated to the specified temperature of the metal powders that are in contact with the surface of the diamond grains to form in places of contact of solid solutions of carbides due to the carbon of the diamond material. When almost complete transition metal carbide powder in the state of the process practically stops. Thus the depth and the geometry of the pits formed on the surface of diamond grains can be adjusted by the size of the metal powder, temperature, time of heating. At temperatures lower than 800°C. the process of dissolution of carbon diamond in the metal flows too slowly, and higher than 1100°C, the temperature is impractical, as heating the diamond above this temperature reduces the impact strength of rough diamonds. After cooling, the sintered fragile agglomerate consisting of diamond grains and the metal powder, and destroy the diamond grains are separated from the main mass of crushed granite. Selected diamond grains are grains in the form of "hedgehog", the surface of which the metal powders are strongly linked with the grain due to the formation of the carbide phase. Diamond grains with attached metal powder is subjected to a treatment with an acid or mixture of acids to dissolve the metal and carbides. The relief surface and the treated diamond grain includes flat areas and depressions the resulting reaction of the carbon of the diamond material and the metal powder.

Choose the size of the metal powders is mainly determined by the desired dimensions of the recesses, which is necessary to obtain on the surface of the grain, the size of the original diamond grains, etc. mainly offered to take the powders from 1 μm to 45 μm. But you can take over the large metal powders.

The number of pits on the surface of diamond grains is regulated by the introduction of a mixture of powders, which when heated in the above conditions do not interact with the diamond grains. In this case there is a partial replacement of metal powders, in which the number of contacts grain diamond - metal powder is reduced and accordingly decreases the total number of dimples on the surface of diamond grains. The process of the diamond grains is also carried out as described above. As powders that are not affected by heating in the interaction with the diamond grains, take, for example, powders of oxides, carbides, nitrides, silicides (aluminum oxide, silicon carbide, tungsten carbide etc).

These powders can be commensurate with metal powders, but can be smaller or larger metal powders.

On the surface of diamond powder described method can be used on ucati pit holes of various shapes, since the processing method of the diamond grains in the vacuum allows you to copy the shape of the surface of the metal powder. This can, for example, take the original metal powders obtained by different technology of their preparation, which often determines the shape of the grains of powder. For example, the powders obtained by spray, have a spherical shape, the powder obtained by reduction of uncertain form, chemically - flocculent form. For more recesses having a dendritic surface, it is necessary to take powders dendritic form.

Thus, the proposed method of obtaining the roughness on the surface of the diamond grains allows without making it difficult to obtain on the surface of the diamond grains of the recess (fossa etching) of the required size, in the required number of specified forms without significant reduction of their original strength.

1. The method of obtaining the roughness on the surface of the diamond grains, including mixing of diamond grains with a metal powder, heating the mixture and separation of the diamond grains from metal powders, characterized in that the heating of the mixture is carried out in vacuum at a temperature of 800-1100°C.

2. The method according to claim 1, characterized in that the metal powders take the powders of iron, Nickel, cobalt, manganese, chromium, and alloys and mixtures.

3. The method according to claim 1, characterized in that Department after heating the diamond grains from their metal powders exposed to acids.

4. The method according to claim 1, characterized in that the mixture of diamond grains and the metal powders are additionally injected powders which, when heated, it does not interact with the diamond grains.