CN103318855A - Preparation method of chromium nitride - Google Patents

Abstract

The invention relates to a preparation method of chromium nitride, belonging to the technical field of preparation of inorganic non-metallic materials. The method uses metal chromium powder with a particle size of more than 200 mesh and at least 3.5N of high-purity reagent as raw material, places the crucible with the raw material in a high-temperature furnace with a controlled atmosphere, and performs high-temperature reaction synthesis in flowing ammonia gas. The synthesis temperature is 800~1200℃, and the temperature is kept for 2~20 hours. The oxygen pressure range in the furnace is 1.013×10 ^4.55 ~1.013×10 ^4.58 Pa, and the nitrogen pressure range is 1.013×10 ^3.11 ~1.013×10 ^6.41 Pa. After the reaction was completed, it was cooled to room temperature in an ammonia stream, and the product was taken out and thoroughly ground to a powder. The chromium nitride prepared by the present invention has only the phase of chromium nitride through XRD analysis, no characteristic peaks of other impurities are observed, no other impurities, and the oxygen content is lower than 1.65%, and the production process is simple, and the raw materials are easy to use. Preservation, suitable for large-scale production.

Description

A kind of preparation method of chromium nitride

technical field

The invention relates to a preparation method of chromium nitride, which belongs to the technical field of preparation of inorganic non-metallic materials.

Background technique

Chromium nitride has many excellent properties, such as high hardness, high melting point, low coefficient of friction, and good electrical conductivity. Due to its super hardness and good corrosion and oxidation resistance, chromium nitride is often used as a protective coating and superhard material, which is a better wear-resistant material than titanium nitride, which is widely used at present. At the same time, chromium nitride is the only material with antiferromagnetism among nitrides, and it is widely used in magnetism. In addition, chromium nitride has important applications in metallurgical industry, electronic industry, high-temperature structural ceramics, and microelectronic devices.

At present, the preparation methods of chromium nitride mainly include: high-energy ball milling method, benzene thermal method, high-temperature self-propagating method, arc discharge plasma method, ammonium solution method, microwave-assisted method, etc. The high-energy ball milling method consumes a lot of energy, has a low yield, and is easy to introduce impurities. There is a certain risk in the benzene thermal method, and carbon residues are likely to be generated during the heating of the organic solution, which affects the purity of chromium nitride. The microwave-assisted method combines microwave heating with carbothermal reduction, and the introduced amorphous carbon is difficult to remove and remains in the product. The arc discharge plasma method uses metal chromium and nitrogen to react in arc discharge equipment to produce products, which requires high equipment, high energy consumption, low production capacity, and is difficult to produce on a large scale. The ammonolysis method is one of the most widely used methods. This method uses chromium chlorides, oxides, sulfides, and chromium complexes as raw materials to synthesize chromium nitride under ammonia atmosphere conditions. However, the raw materials used in this method are not easy to preserve, and harmful gases will be produced in the reaction, causing corrosion of equipment and air pollution. The purity of the chromium nitride prepared by the above-mentioned methods is relatively low, the highest can only reach about 95%, and the oxygen content is relatively high.

Contents of the invention

In view of the defects existing in the prior art, the object of the present invention is to provide a method for preparing chromium nitride, which adopts metal chromium powder as raw material, and reacts at high temperature in an ammonia atmosphere to synthesize chromium nitride, and the equipment and operation process are simple, The resulting product has high purity and low oxygen content.

To achieve the above object, the present invention adopts the following technical solutions:

A method for preparing chromium nitride, which is characterized in that the method comprises the following steps: using high-purity metal chromium powder as a raw material, putting the raw material into a crucible, and then placing the crucible in a high-temperature electric furnace, under the condition of flowing ammonia gas Under high temperature reaction synthesis, the synthesis temperature is 800~1200°C, and the temperature is kept for 2~20 hours; after the reaction is completed, it is cooled to room temperature with the furnace in the ammonia flow, and the product is taken out and fully ground to powder.

The particle size of the metal chromium powder used above is more than 200 mesh, and the purity is more than 3.5N.

During the above-mentioned synthesis reaction, the oxygen pressure in the furnace is controlled to range from 1.013×10 ^4.55 to 1.013×10 ^4.58 Pa, and the nitrogen pressure to range from 1.013×10 ^3.11 to 1.013×10 ^6.41 Pa.

The reaction mechanism of the present invention is as follows:

Metal chromium powder can react with _NH3 to generate CrN, and the reaction formula is as follows:

2Cr+2NH ₃ =2CrN+3H ₂

If there is a chromium oxide film on the particle surface of metal chromium powder, the chromium oxide on the surface can also react with NH ₃ to form CrN, the reaction formula is as follows: Cr ₂ O ₃ +2NH ₃ =2CrN+3H ₂ O

In this way, high-purity CrN with low oxygen content can be obtained.

Compared with the prior art, the present invention has the following prominent substantive features and significant advantages:

The chromium nitride prepared by the present invention has only the phase of chromium nitride through XRD analysis, no characteristic peaks of other impurities are observed, no other impurities, and the oxygen content is lower than 1.65%, and the production process is simple, and the raw materials are easy to use. Preservation, suitable for large-scale production.

Detailed ways

Specific embodiments of the present invention are described below.

Example 1

Using 200-250 mesh metal chromium powder with a chromium content of 99.95% as the raw material, weigh about 5g of the raw material and put it into a graphite crucible. The graphite crucible was placed in an atmosphere furnace, and the gas-solid reaction was carried out in an industrial-grade ammonia environment. The synthesis temperature is 800°C, the temperature is kept for 20 hours, and ammonia gas is continuously fed. Control the oxygen pressure in the furnace to 1.013×10 ^4.55 Pa, and the nitrogen pressure to 1.013×10 ^3.11 Pa. After the reaction was completed, it was cooled to room temperature in an ammonia stream, and the product was taken out and thoroughly ground to a powder.

The chromium nitride synthesized by the method is analyzed by XRD, only has the phase of chromium nitride, and no characteristic peaks of other impurities are observed, and the oxygen content is 2.38%.

Example 2

This example provides a kind of preparation method of chromium nitride, and its specific preparation process and steps are as follows:

Using 200-250 mesh metal chromium powder with a chromium content of 99.95% as the raw material, weigh about 5g of the raw material and put it into a graphite crucible. The graphite crucible was placed in an atmosphere furnace, and the gas-solid reaction was carried out in an industrial-grade ammonia environment. The synthesis temperature is 1000°C, the temperature is kept for 10 hours, and ammonia gas is continuously fed. Control the oxygen pressure in the furnace to 1.013×10 ^4.57 Pa, and the nitrogen pressure to 1.013×10 ^5.01 Pa. After the reaction was completed, it was cooled to room temperature in an ammonia stream, and the product was taken out and thoroughly ground to a powder.

The chromium nitride synthesized by the method is analyzed by XRD, only has the phase of chromium nitride, and no characteristic spectrum peaks of other impurities are observed, and the oxygen content is 1.63%.

Example 3

Using 200-250 mesh metal chromium powder with a chromium content of 99.95% as the raw material, weigh about 5g of the raw material and put it into a graphite crucible. The graphite crucible was placed in an atmosphere furnace, and the gas-solid reaction was carried out in an industrial-grade ammonia environment. The synthesis temperature is 1200°C, the temperature is kept for 4 hours, and ammonia gas is continuously fed. Control the oxygen pressure in the furnace to 1.013×10 ^4.58 Pa, and the nitrogen pressure to 1.013×10 ^6.41 Pa. After the reaction was completed, it was cooled to room temperature in an ammonia stream, and the product was taken out and thoroughly ground to a powder.

The chromium nitride synthesized by the method is analyzed by XRD, only has the phase of chromium nitride, and no characteristic spectrum peaks of other impurities are observed, and the oxygen content is 3.98%. the

Claims (3)

1. the preparation method of a chromium nitride, it is characterized in that, the method comprises the steps: take the high pure metal chromium powder as raw material, raw material is put into crucible, again crucible is placed high-temperature electric resistance furnace, carry out pyroreaction synthetic under the ammonia condition that flows, synthesis temperature is 800 ~ 1200 ℃, is incubated 2 ~ 20 hours; In ammonia flow, cool to room temperature after reaction is finished with the furnace, product is taken out, fully be ground to powder.

2. the preparation method of a kind of chromium nitride according to claim 1 is characterized in that, adopting the granularity of hafnium metal powfer is more than 200 orders, and purity is more than the 3.5N.

3. the preparation method of a kind of chromium nitride according to claim 1 is characterized in that, when building-up reactions, the oxygen pressure scope is 1.013 * 10 in the control stove ^4.55~ 1.013 * 10 ^4.58Pa, the nitrogen pressure scope is 1.013 * 10 ^3.11~ 1.013 * 10 ^6.41Pa.