Research On The Surface Treatment And Valve Material In Coal-Chemistry Industry

Oil-producting technology has been advanced rapidly in coal chemistry industry in China, However, the ball and ball seat are suffered from the abrasion of coal particles, Which result in the reduction of working life. Oxyacetylene spray welding(OXY) and plasma arc powder surface welding (PAS) were carried on the valves to protect the ball and ball seat. Besides, CF8C used in coal chemistry industry was also researched to infer to the volume production in the next period.OM?SEM?XRD?hardness tester and abrasion testing machine were used to the analysis the defect?phase composition?micro-structure?bond strength?abrasion resistance of 2 kinds of Ni60-WC coating made by OXY and PAS. The similarities and differences between two surface treatment processes were compared, the paper also researched the effect of adding form and adding amount of WC on the properties of the coat. At last, the paper researched the casting properties, defect forms, metallographic structure and mechanical properties of CF8C cast steel.The comprehensive properties of two kinds of Ni60-WC coatings prepared by OXY technology were researched, the result showed that:the overall performance of mixed Ni60-WC coating is much better than cast Ni60-WC, it has less internal defects and lower porosity.The WC particles in mixed Ni60-WC can be intact in the coating, while decomposing C element in the cast Ni60-WC coat. The elements in the coating and matrix diffused mutually, the bonding mode is metallurgical combination. The hardness and wear resistance increased with the increase of WC content. Comprehensive comparison of two kinds of Ni60-WC coatings made by OXY showed that the mixed Ni60-WC composite coating is better than the cast Ni60-WC composite coating.The comprehensive properties of two kinds of Ni60-WC coatings prepared by PAS technology were researched, the result showed that:both of the two kinds of the Ni60-WC coating showed a high comprehensive performance. The two types of coating prepared by the process are fully fused, and the porosity of the coating is very low. WC particles in the mixed Ni60-WC produce a certain melting. Both of the 2 coatings bonding with the matrix in the kind of metallurgical combination, there is a melting pool with a depth of about 50um in the presence of the bonding area, and a certain deformation and work hardening occurred on the surface of the substrate. The hardness of the two coatings is uniform and stable. the two coatings shows excellent wear resistance which is directly proportional to the content of WC in the coating. wear morphology of coating is smooth and the Plastic deformation is less than the same coating made by OXY.The casting properties, macro morphology, microstructure and mechanical properties of CF8C cast steel were studied, The result showed that:crack free cast can be produced by the company's existing casting process. The Standard Specification for austenitic stainless steel for A351 ASTM bearing part is met by the casting defects, micro morphology and mechanical properties.