Silicon Carbide/tungsten Carbide Composite Coating

Wear has become one of the main reasons for the failure of modern industrial machinery parts. With the development of industry, more and more high wear-resistant materials are required, and wear-resistant coatings have become the standard of most important wear-prone materials.

In recent years, many experts and scholars have done a lot of research on the preparation process, microstructure and properties, especially the wear resistance of particle-reinforced steel-based composites. The study concluded that tungsten carbide can greatly improve the erosion resistance and wear resistance of steel-based composites. As the volume fraction of WC particles increases, the wear resistance of the material increases first and then decreases. When the volume fraction is 36%. The material has good wear resistance, and the wear mechanism is the "shielding effect" of the tungsten carbide particles on the matrix and the "supporting effect" of the matrix on the tungsten carbide particles.

On the basis of previous researches on silicon carbide and tungsten carbide composites, scholars set out again to try to improve the shortcomings of previous processes through the following schemes.

(1)SiC activation: silicon carbide having a particle size of 0-15 μm is immersed in concentrated nitric acid of 1 to 14 mol/L, and after acidification for 1 to 10 hours, the acid is washed with distilled water;

(2)Acid precipitation: water solution with W concentration of 0.1-1 mol/L was prepared by using tungsten-containing reagent. SiC particles were added to the solution, and the molar ratio of SiC and W was 1:5-5:1, ultrasonic dispersed for 0.5-2 h, then nitric acid solution with concentration of 0.5-2 mol/L was added to the mixture slowly at room temperature. The precursor was prepared by stirring reaction for 2-24 hours at room temperature to 100 ℃, then reacting in water bath at 80-100 ℃ until water was evaporated and dried in vacuum at 100 ℃ for 5-20 H.

(3)Preparation of WO₃/SiC: The precursor was calcined in air for 0.5-5 h at 300-600 ℃ to obtain WO₃/SiC composite powder.

(4)Carbonation: The WO₃/SiC composite powders obtained from the previous step were placed in an atmosphere furnace. The furnace was washed with CO₂ gas at a flow rate of 10-100 ml/min for 0.5-2 h, and then with a flow rate of 50-200 ml/min for the mixture of CO₂ and CO. The volume ratio of CO₂:CO was 0-1:10, and the heating rate of 2-50 min was 700-900 C and the holding time was 2-200 ml/min. To 10h, and then cooled to room temperature, WC/SiC composite powder was obtained.

The compatibility between silicon carbide and metal matrix can be improved by wrapping silicon carbide with tungsten carbide. On the premise of guaranteeing the wear resistance and high temperature resistance of the obtained materials, the application range of SiC can be widened and the amount of precious metal W in the wear resistant composite coating can be reduced. The composite powder can be used as metal additive to strengthen metal. The wear resistance of the matrix greatly reduces the wear of the metal matrix, thus effectively reducing the production cost.

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