The Effect Of Electroless Nickle Plating On SiCp And Preparation Of SiCp/Al Composites On Corrosion Resistance

This article used the method of electroless nickle plating on the SiC particles for surface modification. SiC with different nickle plating process were made from composite materials by powder metallurgy route and pressureless infiltration. SiC with optimal electroless nickle plating process were made from composite materials through thermal insulation respectively 4 h, 6 h, 8 h, 10 h in impregnation temperature by pressureless infiltration. Metallographic microscope, X-ray diffraction, scanning electron microscope and energy dispersive were employed to observe the morphology and analyze the structure of the related composite materials interface. Potentiodynamic polarization curve, EIS and SEM, EDS were used to evaluate electrochemical properties and observe the corrosion morphology in 3.5% Nacl solution of the composite materials.The results showed that nickle plating after one time, the nickle layer is coated by a tiny part of SiC surface, the nickle layer is uneven and thin. Nickle plating After two times, the nickle layer is coated by more than one nickle coating area. The dense and continuous nickle layer is coated by most of SiC surface. When nickle plating after 4times, the nickle layer is coated by nearly the entire region of SiC surface.The nickle layer is continuous and dense.To obtain complete, continuous and dense nickle layer, it is advisable not to less than 4 times.SiC with different nickle plating process were made from composite materials by powder metallurgic. With the increase of number of nickle plated on SiCp, The content of Al Ni phase which is generated by reaction between Al and Ni gradually increased in SiCp/Al composites. The wettability between SiC and Al as well as grain boundary combination between Al and Al was better and better. The corrosion tendency and corrosion rate of SiCp/Al composites were smaller and smaller. The time of the passivation film formation of SiCp/Al composites was delayed and the corrosion resistance of SiCp/Al composites increased. The corrosion resistance of SiCp/Al made of SiC with four nickle plating is best.SiC with different nickle plating process were made from composite materials by pressureless infiltration.With the increase of number of nickle plated on SiCp, the content of Al3 Ni phase which is generated by reaction between Al and Ni gradually increased in SiCp/Al composite materials. Interface reaction: 3SiC+4Al ? Al₄C₃+3Si gradually weakened in SiCp/Al composites. The corrosion tendency and corrosion rate of SiCp/Al composites were bigger and bigger. The time of the passivation film formation of SiCp/Al composites was advanced and the corrosion resistance of SiCp/Al composites decreased. The corrosion resistance of SiCp/Al made of SiC with one nickle plating is best.SiC with optimal electroless nickle plating process were made from composites through thermal insulation respectively 4 h, 6 h, 8 h, 10 h in impregnation temperature by pressureless infiltration. As the heat preservation longer and longer, interface reaction: 3SiC+4Al ? Al₄C₃+3Si gradually strengthened in SiCp/Al composites.The content of Al3 Ni phase and Al₃Ni₂ phase which were generated by reaction between Al and Ni gradually increased in SiCp/Al composites. The corrosion tendency and corrosion rate of SiCp/Al composites were bigger and bigger. The time of the passivation film formation of SiCp/Al composites was advanced and the corrosion resistance of SiCp/Al composites decreased. The corrosion of SiCp/Al composite made in shortest time for impregnation insulation is best.