Decoration Of Nano-material, Study On Preparation And Properties Of Nano-composite Coatings By Electroless Plating

In this paper, the nano- Al₂O₃ and carbide nanotube (CNT) were decorated with copper by electroless plating. The effect of operating condition and component of bath on these composition particles (Cu/α-Al₂O₃, Cu/CNT) after decorating was studied. And the nano-particles before and after being decorated were introduced into electroless bath basing on electroless plating Ni, Cu and P alloy, to make these nano-particles and matrix metal or alloy co-deposit to obtain nano-structure composite coatings. The preparation process of electroless plating was optimized by using perpendicular experiments method. The effect of operating condition, component of bath and heat treatment technics on properties of nano-structure composite coatings was studied, and the co-deposit mechanism was researched. At the same time, the microstructures and components of composition particles and nano-structure composite coatings were characterized by EDS, XRD, SEM and TEM Techniques. The properties of nano-structure composite coatings were evaluated by measuring microhardness, anodic polarization curve and EIS.The result shows that through controlling operating condition and component of bath, nano-α-Al₂O₃ and CNT decorated by copper and Ni-Cu-P, Ni-(Cu-Al₂O₃) -P, Ni-Cu-P/CNT and Ni-Cu/CNT-P coatings can be obtained by electroless plating.During the electroless co-depositing, deposition rate declines after rising with the increasing of nano-particles in electroless bath, which is the same to the change of nano-particles content in coatings. And obtained nano-structure composite coatings by introducing decorated nano-particles into electroless bath, whose structure are very compact, and the content of nano-particles in coatings is high. When the content of composite nano-particles (CU/Al₂O₃) reach 6g/L in electroless bath, the content of nano- Al₂O₃ is 23wt% in Ni-(Cu-Al₂O₃) -P nano-composite coating.The micro-hardness of electroless nano-composite coatings are high, average microhardness exceeds 1000HV. Furthermore, the micro-hardness of nano-composite coatings improved obviously (1780Hv) after heat treatment, and these substance just as Ni₃P, Ni₅P₂ and Cu₃P etc. The resistance to corrosion of nano-composite coatings is excellent. And the amorphous nano-composite coatings obtained by introducing decorated nano-particles into electroless bath are most excellent.