Influence Of Rare Earth On The Performance Of Ni-P Amorphous Coating And Ni-P-β-SIC Composite Coating

Although aluminum alloy is widely used, its application is limited for its low hardness, poor wear resistance and easy to inter granular corrosion. Composite coating is a kind of new type composite coating material which have excellent performance and special function. It not only retains excellent characteristics of the matrix metal but also has the characteristics of dispersed particles of special function.The hardness of β-SiC powder is close to the diamond, and it has good chemical stability, wear-resistance, high temperature resistance, heat resistance, corrosion resistance and other excel ent properties, which is is the ideal second phase reinforcing particles.In order to improve the surface property of aluminum alloy, this topic successfully prepared and studied the strengthening effect of N i-P-β-SiC composite coating on aluminum alloy substrate surface through the chemical composite plating method, and further studied the effect of rare earth on the properties of amorphous coating and composite coating. We adopt optical microscope, SEM and EDS, XRD, micro vickers hardness tester to observe and analysis microstructure, element distribution and organization structure in the composite coating. The main research contents and research results were as follows:(1) We study the relationship between the mechanical properties and particles of β-SiC in the plating solution concentration and determine the best concentration of particles of β-SiC. The results show that adding β SiC particles can significantly increase the hardness and w ear resistance of composite coating. When the concentration of added β-SiC particles in the plating solution is 10 g/L, the N i-P-β-SiC composite coating performance is the best. The coating and substrate interface is clear and good, β-SiC particles uniformly dispersion in Ni-P alloy matrix coating. the coating level is smooth, without pores, cracks and other defects, the average speed, hardness and wear resistance are the best, which is 14.2 μm/h and 580 HV.(2) We respectively study the effect the different kinds of rare earth elements(Y/La) and its content to the chemical plating of N i-P amorphous microstructure, deposition rate, hardness and corrosion resistance, etc. These results show that both kinds of rare earth elements add to improve the P content in N i- P amorphous coating and coating of the degree of crystallization, has realized the purpose of the deposition rate, coating hardness and corrosion resistance increased significantly, and the effect of Y(NO3)3 is more pronounced. Adding 150 mg/L Y(NO3)3 in the coating is the best comprehensive performance. When the content of P in the coating is 12.6%,the microhardness reach 558.6 HV, deposition rate is 26.5 μm/h. It obtained significantly higher resistance to corrosion in 5% NaCl solution.(3) We focuses on rare earth elements Y to effect N i-P-β-SiC composite coating performance. The influence of the research shows that Y(NO3)3 can improve the performance of N i-P-β-SiC composite coating which is include of plating rate, hardness, corrosion resistance and abrasion resistance. When the concentration of Y(NO3)3 to add 1.0 g/L in Ni-P-β-SiC,its omprehensive performance is the best. The deposition rate is 15.8 μm/h, hardness is 590 HV, the performance of corrosion resistant has been improved significantly.