JPH0139966B2 - - Google Patents

Description

Claim 1: A method for treating diamond, comprising: bringing the diamond into contact with a mold made of a metal or an alloy thereof that melts diamond carbon;
(i) heated under vacuum, (ii) heated in an inert gas atmosphere, or (iii) within a temperature range of ~1800°C and at which the respective temperatures of the diamond and the mold are the same. a gas selected from the group consisting of air, hydrogen, water vapor, carbon dioxide, or mixtures thereof, which does not react with the diamond itself at the temperature, but reacts with the diamond carbon dissolved in the metal or alloy; heating in an atmosphere of said gas, whereby said mold in contact with said diamond dissolves diamond carbon in contact therewith and changes the appearance of said diamond.

2. The method of claim 1, wherein the mold is made of iron, nickel, cobalt, chromium or platinum, or alloys thereof.

TECHNICAL FIELD The present invention relates to a method for processing diamond that can be used in the manufacture of single crystal diamond tools and jewelry.

BACKGROUND TECHNOLOGY A method for the mechanical treatment of diamond with diamond powder deposited on the surface of a high-speed rotating or vibrating metal machine tool (cutting, grinding, boring);
Processing methods using laser, electron or ion beams (cutting and mainly boring) are also known. Methods of forming pores in diamond crystals using oxygen injection at high temperatures are known (PN
Kiseleva, industrial diamonds (Russian),
M., Nedra Publishers, 1964, pp. 24-55; Zh.
Bonrua, Diamond Cutting (Russian, "Synthetic Diamonds in Industry", Kiev, Naukova
Dumka Publishing House, 1974, pp. 60-65).

It is also known to treat diamond by contacting it with a mold in an oxygen atmosphere at 600°C. The diamond is treated by burning off the heated diamond by contacting it with a heated mold in oxygen.

The mold is manufactured from platinum, ceramic or other materials that withstand heating to the desired temperature in an oxygen atmosphere (German Patent No. 1013540, Cl. 67a, 21).

According to conventional methods, the diamond and mold must be heated to different temperatures and moved relative to each other, thus creating complications in diamond processing. During processing according to the known method, in addition to the most heated part of the diamond to be melted, it is inevitable that adjacent slightly less heated parts will melt, which leads to a reduction in precision in diamond processing. .

DISCLOSURE OF THE INVENTION The present invention provides a method for treating diamond, comprising:
The objective is to provide diamond and mold contact conditions that increase precision and enable simpler manufacturing techniques.

This objective is achieved in the following way.

That is, this diamond processing method involves bringing the diamond into contact with a mold made of a metal or an alloy thereof that melts diamond carbon;
(i) heated under vacuum, (ii) heated in an inert gas atmosphere, or (iii) within a temperature range of ~1800°C and at which the respective temperatures of the diamond and the mold are the same. a gas selected from the group consisting of air, hydrogen, water vapor, carbon dioxide, or mixtures thereof, which does not react with the diamond itself at the temperature, but reacts with the diamond carbon dissolved in the metal or alloy; heating in an atmosphere of the gas, whereby the mold in contact with the diamond melts the diamond carbon in contact with it and changes the appearance of the diamond.

Preferably, the mold is made of iron, nickel, platinum or alloys thereof.

To speed up the diamond processing time, contacting is preferably carried out in a gas atmosphere which does not react with the diamond at the contacting temperature, but which reacts with the diamond carbon dissolved in the metal or alloy at the same temperature.

The above gases include hydrogen, water vapor, carbon dioxide, air, oxygen, or mixtures thereof.

The method of the invention substantially simplifies the processing of diamond and makes it possible to form holes, passages and complex grooves in the diamond, and also allows the production of products with complex shapes such as micro-cutters. do. Furthermore, the invention allows the formation of relief images as well as the matting of diamond surfaces. Another feature of the method of the invention is that the mold is substantially free of wear during the diamond treatment process, and that a single mold can be used for multiple diamond treatments.

DETAILED DESCRIPTION OF THE INVENTION Depending on the final shape of the product, the diamond processing method can be implemented in many ways. For example, the diamond is brought into contact with a large mold (compared to the diameter of the diamond) in order to obtain a diamond with a flat surface or relief image. Contacting takes place in an inert atmosphere or under vacuum. The mold is made of a metal or alloy that can dissolve as much carbon as possible, such as iron or iron-based alloys. The treatment temperature is chosen close to the eutectic point of the metal or alloy with carbon. If the mold is made of iron, the diamond contacts at a temperature of 1100℃. This is because the eutectic point of iron and carbon is 1147°C.

In order to obtain a matte image or to make the diamond surface matte, the mold preferably consists of a thin layer of metal or alloy applied to the diamond surface in the form of a paste or by sputtering. Preferably, the diamond contacts the mold at a temperature of 600 to 1100°C. The process is carried out in a gas atmosphere which does not react with the diamond at the contact temperature, but which reacts with the carbon dissolved in the metal or alloy at that temperature. It is disadvantageous to contact the diamond with the mold at temperatures below 600°C. This is because below 600°C the dissolution rate of the diamond into the metal mold is slow, while at temperatures above 1100°C the diamond surface is etched too deeply. In such applications, it is preferred that the mold is made of platinum, nickel, iron and chromium. The most preferred material is platinum. Because,
Platinum can be used in an oxidizing atmosphere without being coated with an oxide film and at lower temperatures than other metals (e.g.
This is because diamond carbon begins to melt at 600℃). At high temperatures, to avoid direct etching of the diamond by the gas, the oxygen pressure is preferably reduced or gases that react slowly with the diamond are used (the gases are chosen in an order that reduces the rate of reaction with the diamond). Becomes: O ₂ -
Air - CO ₂ - H ₂ O - H ₂ ).

In order to remove a thick layer of diamond (comparable to the diameter of the diamond) when creating holes in complex tools, micro-cutters or diamonds, the diamond does not react with the diamond at the contact temperature but melts into the complex material. The contact is preferably carried out at a temperature of 1100 to 1800° C. in an atmosphere of a reacting gas with the diamond carbon. Contact below 1100°C is disadvantageous as the treatment process is too long, and above 1800°C graphitization of the diamond begins. At 1100 to 1300°C, Fe, Co, Ni or their alloys, and the metals and Mn and
Preferably, a mold made of an alloy with Cr is used. At temperatures above 1300°C, molds are made from platinum or platinum-based alloys. 1100℃ to 1800℃
The contacting is preferably carried out at a temperature of 100 ml, in an atmosphere of hydrogen with an amount of water vapor added to increase the reaction rate.

In all applications, after treatment is completed, the diamond is cleaned from the type of metal or alloy attached to it, or from a thin graphite film on the treated surface. Cleaning is carried out by placing the diamond in a boiling mixture of concentrated hydrochloric acid and nitric acid in a 3:1 volume ratio followed by immersion in boiling concentrated sulfuric acid saturated with K ₂ Cr ₂ O ₇ at room temperature.

The invention is further illustrated by the following examples.

Example 1 The mold for processing diamonds is approximately 0.1 mm.
It was a 2mm thick iron plate with a carved pattern at the depth of . A diamond was placed on top of the pattern.
The diamond was contacted with the mold for 3 hours at 1100° C. under a vacuum of 10 ⁻² Torr. After contact of the diamond with the mold, a mirror image of the pattern was obtained on the diamond facet with a relief of height corresponding to the depth of the engraving.

Example 2 The process was carried out as described in Example 1, except that the contact was carried out in an argon medium.

Example 3 A (100) facet of diamond was obtained by mechanical treatment. An alcoholic solution of an equal weight mixture of calohony and H ₂ PlCl ₆ was applied to the facets to form a pattern image. A diamond with a pattern formed on its surface as described above was exposed to air for 600 minutes.
heated to ℃. Before the temperature reached 600°C, the mixture decomposed, leaving a finely dispersed platinum layer as a mold on the diamond surface. After the diamond was in contact with the mold for 5 hours at 600°C in an air atmosphere,
A fine matte image of the pattern appeared on the surface of the diamond.

Example 4 A mold with a pattern made from a finely dispersed platinum layer was formed on the (111) facets of a diamond in a similar manner (Example 3) _. After 1 hour of contact with the mold in a gas atmosphere consisting of % _H2 , a much sharper image of the pattern appeared on the diamond than in Example 3.

Example 5 86% Ni by weight on approximately 10 mg of diamond crystals
Diameter made of an alloy consisting of and Fe14% by weight
A 0.15 mm wire-shaped mold was placed. Both ends of the wire were tied to a nickel loop that could be lowered under gravity. A ring with diamonds and wire was placed in a corundum tube with an inner diameter of 10 mm. The tube was heated in an electric furnace and then a stream of dry hydrogen was added at atmospheric pressure to
It passed at a speed of h. 0.64mm inside the diamond
grooves of depth were formed within 13.5 hours at 1250°C.
The average cutting speed was 0.05 mm/h.

Example 6 An equilateral triangular mold with 1.5 mm sides and 0.1 mm thickness was placed on a 0.85 mm thick triangular plate of compressed twinned diamond. The mold is Example 5
It was made from the alloy used in The diamond was contacted with the mold at 1200° C. for 45 hours in a stream of dry hydrogen. After contact, a triangular through-hole with a uniform inner wall of the same size as the mold was formed in the diamond. The processing speed was 0.02 mm/h.

Example 7 A hexahedral mold with a thickness of 0.1 mm and a hole corresponding to a gear having 14 teeth with an outer diameter of 2.7 mm was placed on a compressed twinned diamond in the shape of a triangular plate. The mold was manufactured from the alloy used in Example 5. After 29 hours of exposure to a dry hydrogen stream at 1200°C,
The mold was penetrated into the diamond to a depth of 0.4 mm in order to form from the diamond a gear of a shape and size corresponding to the hole in the mold. The processing speed is
It was 0.014mm/h.

Example 8 1×1 in the shape of a square nickel plate
A mold with a size of ×0.5 mm was placed on the diamond crystal. The diamond was heated to a dew point of +25°C (H ₂ O
The mold was contacted for 50 minutes at 1230° C. in a hydrogen stream at a vapor pressure of 24 Torr. The mold penetrated the diamond crystal to a depth of 0.27 mm. As a result, the processing speed is 0.3mm/h
It was hot.

Example 9 A mold made of an alloy consisting of 90% by weight of Nickel and 10% by weight of Cr and having a size of 1×1×0.05 mm was placed on a diamond crystal. Diamonds were heated at 1250°C in a hydrogen stream with a dew point of +10°C (H ₂ O vapor pressure 9 Torr).
for 3 hours. After contact, a 0.9 mm deep square space was formed within the diamond. The processing speed is
It was 0.3mm/h.

Example 10 A template in the shape of a square platinum plate with dimensions of 1 x 1 x 0.05 mm was placed on a diamond crystal. The diamond was contacted with the mold for 30 minutes at 1600° C. in a stream of dry hydrogen. After contact, a square space with a depth of 0.05mm is created.
It was formed in diamond at a processing speed of 0.1 mm/h.

Industrial Applicability The diamond processing method can be used in the production of crystalline diamond tooling and jewelry.