Method for preparing cementite

A cementite and cold-press forming technology, applied in the field of metal material preparation, can solve the problems of low diamond grade, stagnation, continuous diamond formation and lack of growth, etc., to achieve high output, improve quality and quantity, promote continuous formation and effect of growth

Inactive Publication Date: 2008-10-15
SHANDONG UNIV
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Problems solved by technology

For a long time, catalyst metal plus graphite and diamond have been widely used at home and abroad. In this process, although cementite can also be produced, as the diamond grows, a large amount of cementite will be consumed. Due to the physical, chemical and metallurgical environment, the cementite consumed by the growth of diamond cannot be replenished. Therefore, the continuous formation and growth of diamond stagnates due to the lack of cementite. Therefore, the diamond produced by traditional methods is of low grade. , small particle size

Method used

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  • Method for preparing cementite

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Embodiment 1

[0013] Embodiment 1: A. mix 88 parts of iron powders, 1 part of nickel powders, 3 parts of graphite powders by weight, dry and remove moisture;

[0014] B. The mixed powder is cold-pressed into a sheet under a pressure of 600MPa;

[0015] C. Surface cleaning and removal of dirt;

[0016] D. Alternately put the cold-pressed forming blank and the graphite sheet into the pyrophyllite cavity and place the pyrophyllite on the six-sided top press in a weight ratio of 2:1;

[0017] E. Apply an ultra-high pressure of 5GPa to the pyrophyllite at 1350 degrees Celsius and keep it for 90 seconds.

Embodiment 2

[0018] Embodiment 2: A. 91 parts of iron powders, 2 parts of nickel powders, 6 parts of graphite powders are mixed uniformly by weight, dry to remove moisture;

[0019] B. The mixed powder is cold-pressed into a cylindrical shape under a pressure of 650MPa;

[0020] C. Surface cleaning and removal of dirt;

[0021] D. Put the cold-pressed blanks and the graphite sheets alternately into the pyrophyllite cavity with a ratio of 3:1 by weight and place the pyrophyllite on the six-sided top press;

[0022] E. Apply an ultra-high pressure of 2GPa to the pyrophyllite at 1300 degrees Celsius and keep it for 2 minutes.

Embodiment 3

[0023] Embodiment 3: A. 95 parts of iron powders, 3 parts of nickel powders, 9 parts of graphite powders are mixed uniformly by weight, dry to remove moisture;

[0024] B. The mixed powder is cold-pressed into a cylindrical shape under a pressure of 700MPa;

[0025] C. Surface cleaning and removal of dirt;

[0026] D. put the cold-pressed blank and the graphite sheet alternately into the pyrophyllite cavity with a ratio of 4:1 by weight and place the pyrophyllite on the six-sided top press;

[0027] E. Apply an ultra-high pressure of 3GPa to the pyrophyllite at 1200 degrees Celsius and keep it for 4 minutes.

[0028] The resulting cementite is shown in the accompanying drawing, from which it can be seen that the proportion of cementite has reached more than 90%.

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Abstract

The invention relates to a method for preparing cementite, which has the following steps: A. 80-95 by weight of iron dust, 1-3 by weight of nickel powder, and 3-9 by weight of graphite powder are uniformly mixed, and then is dried; B. the mixing powder is cold press moulding at the pressure of 600-700MPa; C. the surface is clear to get rid of dust; D. 2-5:1 by weight of cold press moulding blank and graphite flake are alternately put into the cavity of pyrophillite which is fixed on the hexahedral anvil presser; and E. the pyrophillite keeps for 90s-4min under the ultra high pressure of 2-5GPa, at the temperature of 1200-1500 degree C. Iron dust, nickel powder graphite powder of a certain proportion react in a certain condition to produce a great lot of cementite, which greatly increases the mass and quantity of man-made diamond. And the cementite prepared by this method has a high output, and improves the continuous formation and growth of the diamond grain in the process of diamond synthesize.

Description

technical field [0001] The invention relates to a method for preparing metal materials, in particular to a method for preparing cementite. Background technique [0002] We know that graphite carbon and diamond are different manifestations of carbon, which are allotropes of carbon. The essence of synthetic diamond is to transform the graphite structure of carbon into diamond structure under artificial intervention. In 2002, "Science Bulletin" Volume 47, Issue 9, Page 669 published the research results of Xu Bin et al. titled "The Structure of the Metal Coating and the Growth of Iron-based Catalyst Synthesized Diamond". In the paper, graphite carbon, The transformation relationship between cementite and diamond proves that the transformation from graphite carbon to diamond is not a simple rearrangement process of carbon atoms, but a series of intermediate links. Among them, under the attraction of γ-(Fe, Ni) in the catalyst, the cementite separates the carbon atom group from...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J3/06
Inventor 崔建军崔潇李木森万桂怡
Owner SHANDONG UNIV
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