| Ni-P composite coatings is an ideal plating to replace the chrome plating and zincplating for its high strength, high hardness, good abrasion resistance, corrosion resistance,uniform thickness, high weldability, magnetic shielding and high electrical conductivity andother excellent performance, and it has been widely applicated in the automotive, aerospace,computer, electronics, machinery, chemical industry, light industry and petroleum industry etc.With the rapid development of nanotechnology, the study of Ni-P nano composite coating isbecoming more and more widely. Carbon nanotubes have the characteristics of very largelength-diameter ratio, high elastic modulus and strength, while GO has the characteristics ofvery large specific surface area and intensity. It is expected to obtain higher hardness, betterwear resistance and corrosion resistance that adding both of these two carbon materials intocomposite coating as the reinforced phase for their characteristics of high strength,self-lubricating performance and chemical stability. In this paper, CNTs/GO-Ni-P compositecoatings were prepared by electroless plating and then were heat-treated. Mechanism for theway of both content of reinforced phases and heat treatment process influence compositecoatings was discussed.Firstly, CNTs-Ni-P composite coating was prepared by electroless composite plating.We get the best content of carbon nanotubes through comparing and analyzing the propertiesof composite coating carefully. The results indicated that composite coatings will achieve bestperformance while the content of CNTs was0.02g/L. In this case, hardness of coating reach to432.5HV, wearing capacity was lowest with only0.9%, while the best corrosion resistancewas obtained.Secondly，GO/CNTs-Ni-P composite coating was prepared by electroless compositeplating. We get the best content of GO through comparing and analyzing the properties ofcomposite coating carefully. The results indicated that composite coatings will achieve bestperformance while the content of GO was GO:CNTs=1:5. In this case, hardness of coatingreach to555.7HV, wearing capacity was lowest with only0.26%, while the best corrosionresistance was obtained. By the way, mechanism of how GO disperse CNTs was studiedthrough FT-IR figure of GO. It turned out that the Oxygen-containing groups on the surface ofGO are able to adsorb CNTs agglomeration and disperse CNTs effectively. Then we will getstable suspension. Thirdly, optimum SDBS content of preparation of composite coating was researched. Itcan be indicated that composite coatings will achieve best performance while the content ofSDBS is0.2g/L.Finally, heat treatment was carried out on composite coatings. The processingconditions of heat treatment: the temperature is400℃, the time of heat preservation is1h, andin the whole process the composite coatings were protected by argon gas. Mechanism of howheat treatment influence the mechanical properties of composite coatings were also discussed.The results show that heat treatment could make composite coatings crystallization andrelieving of internal stress in composite coatings. Consequently, the mechanical properties ofcomposite coatings were improved. |
