Preparation method and process of chromium carbide
Release time:
2021-12-07 10:00
Source:
The invention belongs to the technical field of ferroalloy preparation, and specifically relates to a preparation method of chromium carbide. Chromium carbide is a high melting point inorganic material, which has good wear resistance, corrosion resistance and oxidation resistance in high temperature environment (1000-1100). Due to its special high-temperature properties, it is widely used as a thermal spray material and additive for metal surface protection technology in the cemented carbide industry. At present, the process of producing chromium carbide is difficult to control due to the high reaction temperature, the danger of heating in the hydrogen flow, and the process parameters are difficult to control, resulting in unstable product quality, difficult to reach the temperature, and unable to carry out large-scale industrial production. Since the metal impurities in the raw material chromium cannot be removed during the carbonization process, the method requires high purity of the raw material chromium, and the production cost is high. Chromium and chromium carbide have high hardness, so they need to be crushed by a hard crusher in the preparation of raw materials and the processing of finished products, and the processing cost is high.
The technical problem to be solved by the invention is that the existing preparation method of chromium carbide is not easy to mass-produce, and the quality of the prepared chromium carbide product is unstable. According to the technical solution to solve the technical problem adopted by the present invention, a method for preparing chromium carbide is provided, which includes the following steps: mixing the raw materials evenly according to the weight ratio, pressing, and drying to obtain a molded product, heating and cooling in a nitrogen atmosphere, To obtain chromium carbide; the prepared raw materials include chromite, carbonaceous powder, iron powder and binder, and the amount of carbonaceous powder added is controlled according to the following percentage relationship: 100 mass% of carbonaceous powder = (1-mass% 3/4 of cr in raw chromite) mass% of c in product chromium carbide mass of product chromium carbide. Wherein, in the preparation method of chromium carbide, the weight ratio of raw materials is: chromite iron ore 100 parts, carbonaceous powder 25-35 parts, iron powder 10-50 parts, binder 5-20 parts. The following raw materials were included in parts by weight: chromite ore 100 parts, carbonaceous powder 26-33 parts, iron powder 25-30 parts, binder 8-15 parts. The chromium oxide is selected from at least one of Cr2O3 or Cr (OH) 2. The carbonaceous powder is selected from at least one of a graphite powder or a carbon black powder. The binder is at least one selected from water, starch or polyvinyl alcohol. The particle size of iron powder is -140 ~-80 mesh. In the method for preparing chromium carbide, the heating step includes a preheating section, a transition section and a sintering section; the temperature of the heating step is increased from 400 to 1550. The temperature of the preheating section is increased from 400 to 800, and the heating time is 4-8 hours. The temperature of the transition section is increased from 800 to 1200, and the heating time is 3-7 hours; the temperature of the sintering section is increased from 1200 to 1550, and the heating time is 8-12 hours.
The beneficial effects of the present invention are: it is beneficial to temperature control and the continuity of the reaction process, and the apparent density of the prepared chromium carbide product can be further improved. The method can be completed under normal pressure without being carried out under vacuum conditions, and the operation process is simplified, The requirements for equipment are reduced, the quality of the prepared product is stable, the reaction temperature is easy to control, and it is suitable for large-scale production.
Chromium carbide
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