Effect of Polyethyleneimine on Composite Brush Plating with Nanometer Si_3N_4

Effects of polyethyleneimine(PEI) surfactant on the dispersibility of nanometer Si3N4 in the(Ni-P)-nanometer Si3N4 composite brush plating solution and on the structure and properties of the coating of(Ni-P)-nanometer Si3N4 composite brush plating were studied.Optimum content of PEI in the composite brush plating solution was determined.Experimental results show that PEI surfactant can effective prevent flocculation and conglomeration of Si3N4 particles in the composite brush plating solution,and that concentration of PEI surfactant in the composite brush plating solution has remarkable effect on microhardness and wear resistance of the composite brush plating coatings: A(NiP)-nanometer Si3N4 composite brush plating solution with particles even dispersion and stable suspension can be obtained as the concentration of PEI surfactant in the plating solution is 0.8 g/L.Coating of composite brush plating obtained under this condition possesses dense micro-structure,even particle distribution,smallest wear rate and highest micro hardness.