CN1298757A

CN1298757A - Process for preparing microcrystalline diamond

Info

Publication number: CN1298757A
Application number: CN 00110586
Authority: CN
Inventors: 朱贵增; 郭东章; 李贵; 朱家永
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-06-30
Filing date: 2000-06-30
Publication date: 2001-06-13

Abstract

A preparation method of microcrystalline diammond includes the following steps: preparing material, synthetic column formation, drying, assembling, synthesizing diamond, crushing and post-treatment, grading and packaging. The said method use purified natural 3R type graphite powder and special catalyst as raw material, the synthetic column formation uses the continuous method, drying temperature is 80-150 deg.C, and drying time is more than 2 hrs. The synthetic column is mounted in the pyrauxite synthesis cavity, a hexagonal push press is used to apply pressure and at the same time, heating to obtain the diamond. The average conversion rate can be up to higher than 50%, the diamond is high in strength and fastness to wear.

Description

A kind of preparation method of microcrystalline diamond

The invention belongs to a kind of adamantine preparation method, particularly a kind of crystallite, the adamantine preparation method of ultracrystallite.

Existing diamond fabrication method, how with the static pressure method diamond synthesis, the carbon materials of employing is all artificial colloid graphite, and this kind method is made diamond, and its graphite/adamantine conversion ratio has only 17%～20%.Existing diadust production, mainly be to adopt inferior grade coarse gold hard rock to make through Mechanical Crushing processing, diamond crystalline form or cutting edge are destroyed, make its inner micro-crack that produces, cause intensity not high, influence result of use, the diamond that this kind method is produced can only be used as ultra-hard abrasive material, and can not be as the functional material with specific physical performance.In recent years, though useful artificial aquadag is made the directly synthetic melee of carbon source, because of per unit area yield is low, the cost height, and fail to form large-scale production.Another important source material that diamond synthesis is used is a catalyst material, and catalyst alloy commonly used in the prior art is Ni ₇₀Mn ₂₅Co ₅, this alloy contains noble metal Co, the cost of material height, and production technology needs through vacuum metling, hot rolling cogging, annealing and pickling, cold roughing, finish rolling, operations such as punching are finished, and technological process is long, the cost height, and consume rare precious metal Co.The assembling mode of synthetic post adopted a slice graphite to add the eclipsed form assembling of a slice catalyst more when it made diamond, and this assembling mode also defines graphite/adamantine conversion ratio, made its conversion ratio impossible high.

The object of the present invention is to provide a kind of graphite/diamond conversion ratio height, utilize the method for producing high-quality microcrystalline diamond through the natural 3R graphite of purifying.

Method of the present invention is to select for use through the natural 3R powdered graphite of purifying to make raw material, under the effect of special-purpose catalytic alloy powder, with the synthetic crystallite of static pressure method, ultracrystallite diamond.

Step of the present invention comprises: the preparation of special-purpose catalytic alloy powder, batching, synthetic post shaping, drying, assembling, diamond synthesis, broken and post processing, classification and packing etc.

The design of special-purpose catalytic alloy powder is to be converted into adamantine crystal structure and the electronic structure respective conditions is a foundation with graphite, and be criterion with the d electronics percentage concentration of alloy constituent element about 40%, consider that simultaneously synthesis technique and economic effect factors carry out superior design.The constituent element of alloy constitutes: be base with Ni, Ni content is 70～75%; Mn is a main alloy element, and Mn content is 25～30%; Contain have an appointment 2～4% Cr or Cu; It is ± 0.05～0.5% that the elder brother closes rare earth.Alloy is after mechanical alloying is handled, and the institutional framework of alloyed powder is single-phase austenite, and its process is: alloying element powder is according to a certain ratio mixed; The alloy material that mixes is packed in the high energy grinding machine, vacuumize after the sealing; In the high energy grinding machine of sealing, charge into protective gas, as high-purity Ar; Realize alloying process in the high energy grinding machine, the time is 30～50 hours; To the alloyed powder of finishing mechanical alloying after cooling voluntarily, discharging; Alloyed powder is sieved and classification; Catalytic alloy powder drying after the classification is sealed up for safekeeping.

Batching: choosing through the natural 3R type graphite powder after purifying is that (this kind graphite powder contains 3R type graphite and can reach more than 80% raw material, its fixed carbon content reaches more than 99%) be mixed in proportion through the special-purpose catalytic alloy powder of said method manufacturing, fully stir be mixed after, add an amount of volatility bonding lubricant, capable again stirring and evenly mixing, the granularity requirements of its graphite and catalyst powder is 0.1～0.06mm; Raw material proportioning (weight ratio), graphite: catalyst is 1: 3～3: 7.

Synthetic post is shaped: the graphite that configures and catalyst compound are packed in the special shaping dies, carry out press forming on ordinary press, the control of pressure will be according to the mould size, charging what, the pine dress ratio of powder, technical conditions such as true specific gravity are determined.Cause synthetic column performance poor reproducibility for overcoming by elder brother's material and single shaping, influence the drawback of diamond synthesis, synthetic post is shaped and adopts the progressive forming mould, can significantly improve the production efficiency of synthetic post.Mould capacity 2Kg～6Kg, 100～200 posts that once can be shaped, synthetic column diameter is got φ 20mm, and three kinds of φ 23mm φ 25mm become column length to decide by the height requirement of actual synthetic cavity (pyrophillite synthesizes the chamber) entirely, and promptly length can be cut arbitrarily according to demand.

Oven dry: the synthetic post that will be shaped is put the oven dry of people's drying baker, and bake out temperature is 80～150 ℃, and drying time is more than 2 hours.

Assembling: the synthetic post assembling of crystallite, adopt the single-column overall package; The two folded formula assemblings of two posts are adopted in the synthetic post assembling of particulate.

Synthetic: be to being assembled in the diamond synthesis mould, crystallite in the pyrophillite cavity or thin brilliant synthetic post are exerted pressure with cubic hinge press and are heated simultaneously, realize the phase transition process that graphite → diamond changes.

Fragmentation and post processing: will carry out fragmentation through the Buddha's warrior attendant stone column after synthetic, broken back adopts electrolysis or acidic treatment to carry out post processing, remove the graphite of not participating in reaction by post processing, catalyst and pyrophillite residue, the diamond water that obtains is cleaned up, send into then in the drying box and dried 1～2 hour down, take out back standard screen sieve classification, then encapsulation at 100～200 ℃.With the microcrystalline diamond that the inventive method is made, conversion ratio on average can reach more than 50%, the diamond intensity height, and wearability is good, can be used as new function material, has broad application prospects.

Further narrate content of the present invention below in conjunction with drawings and Examples:

Fig. 1 is a process chart of the present invention,

Fig. 2 is charge of oil material schematic diagram to be pressed in the synthetic post forming process,

Fig. 3 begins to press the shape schematic diagram for synthesizing in the post forming process,

Fig. 4 is for extruding synthetic post schematic diagram in the synthetic post forming process.

Embodiment: raw material is chosen China Jilin huge rock area and is produced and the natural 3R type graphite powder (contain 3R type graphite more than 80%, fixed carbon content reaches more than 99%) through purifying, catalytic alloy powder, and alloying component is two kinds:

A. synthetic microcrystalline diamond Ni base, composition: the Ni surplus, Mn24～26%, Cr3～5%, the alloy powder granularity is less than 200 orders;

B. synthetic melee Ni base, composition: the Ni surplus, Mn24～26%, Cr2～3%, the alloy powder granularity is less than 100～200 orders,

Preparation catalyst powder is raw materials used, and oxygen content should be lower than 100PPM, and granularity requirements 180～200 orders prepare the catalyst powder according to preceding method.After raw material is chosen, prepare burden in proportion, proportioning is: catalyst: graphite is 2.5: 7.5～3: 7.The interior mixing of the batch mixer of packing into after raw material prepares, mixing time is 0.5～1 hour, is anti-oxidation; when batch mixing, can charge into protective gas, after the material mixing, pour the bonding lubricant into; stirred again 3～5 minutes, and adopted the sticking profit agent of the easy drying of one-level phenolic resins and acetone (analyzing pure) preparation.Raw material blending is packed into later on and is pressed shape in the shaping dies, extrudes synthetic post, assembles after the oven dry will synthesize post and pack in the synthetic chamber of pyrophillite, so that diamond synthesis.

The single-column overall package is adopted in the synthetic post assembling of crystallite, and two ends are lined with the thick 1.0～1.5mm of being graphite carbon plate respectively.The two folded formula assemblings of two posts are adopted in the synthetic post assembling of particulate, remove synthetic post, and two ends are lined with respectively outside the thick 1.0～1.5mm of the being graphite carbon plate, also need to fill up between two posts the carbon plate of the thick 1.2～1.5mm of being of a slice.The carbon plate diameter is pressed the internal diameter of synthetic cavity and is determined that Graphite pad will have higher resistance, can adopt the graphite carbon plate of degree of graphitization lower (general available degree of graphitization 65～75%) to make pad.Adopt the cubic hinge press diamond synthesis after assembling, synthesis technique adopts one-time continuous to heat up according to the P-T phasor of carbon, the way of secondary pressurization.Temperature is controlled at 1400～2500 ℃ of pressure at 100MPa～104MPa, the time: 3～6 minutes.After diamond was synthetic, through broken, post processing divided grade packaged at last.

Claims

1, a kind of preparation method of microcrystalline diamond comprises batching, synthetic post shaping, drying, assembling, diamond synthesis, fragmentation and post processing, classification and packaging and other steps, it is characterized in that:

A. the used raw material of diamond synthesis is 3R type graphite powder and special-purpose catalyst powder through purifying, the proportioning (weight ratio) of graphite powder and catalyst powder, and graphite: catalyst is 1: 3～3: 7, the granularity requirements of graphite and catalyst powder is 0.1～0.06mm;

B. synthetic post is shaped and adopts progressive forming, mould capacity 2Kg～6Kg, and synthetic column diameter is got φ 20mm, φ 23mm, φ 25mm;

C. oven dry is put the oven dry of people's drying baker with the synthetic post that is shaped, and bake out temperature is 80～150 ℃, and drying time is more than 2 hours;

D. assembling, the synthetic post of crystallite adopts the single-column overall package, and the synthetic post of particulate adopts the two folded formula assemblings of two posts;

E. diamond synthesis is reflected in the pyrophillite cavity and finishes, and heats simultaneously with the cubic hinge press pressurization, and temperature is controlled at 1400～2500 ℃, and pressure is 100MPa～104MPa, the time: 3～6 minutes.

2, the preparation method of a kind of microcrystalline diamond according to claim 1, it is characterized in that special-purpose catalytic alloy powder constituent element constitutes: be base with Ni, Ni content is 70～75%; Mn is a main alloy element, and Mn content is 25～30%, contains have an appointment 2～4% Cr or Cu; Mishmetal is ± 0.05～0.5%.

3, the preparation method of a kind of microcrystalline diamond according to claim 1 is characterized in that the synthetic post of said crystallite adopts the single-column overall package, and two ends are lined with the thick 1.0～1.5mm of being graphite carbon plate respectively; The two folded formula assemblings of two posts are adopted in the synthetic post assembling of particulate, remove synthetic post, and two ends are lined with respectively outside the thick 1.0～1.5mm of the being graphite carbon plate, also need to fill up between two posts the carbon plate of the thick 1.2～1.5mm of being of a slice, and the carbon plate diameter is pressed the internal diameter of synthetic cavity and determined.

4, according to claim 1 or 3 in the preparation method of described a kind of microcrystalline diamond, it is characterized in that diamond synthesis, the Graphite pad that will fill up during the synthetic post of assembling will have higher resistance, generally adopts the lower graphite carbon plate of degree of graphitization to make pad.