Electroless Co-P-PTFE composite coatings

On the basis of its structures, surface properties and adhesion with iron, cobalt was selected as the matrix in a composite coating to support a load. PTFE was inserted into the matrix to assist lubrication. A composite coating of Co-P-PTFE was prepared by electroless plating. The composite consists of 9.0 percent PTFE, 5.1 percent P and 85.9 percent Co by weight. The properties and structures of Co-P-PTFE composite were studied by X-ray, SEM and ESCA, etc. The results show that the composite had high hardness and good adhesion to the matrix after plating. X-ray analysis showed that the composite was a hexagonal system and its crystal showed no change except that the lattice constant increased, evidently after it was treated with heat. The cobalt (100) face of the hexagonal system parallels the matrix surface and a solid solution was formed in the composite treated with heat. The composite has a strong tendency toward a certain direction. AES analysis indicated that the proportion of Co, P and F content is 13.9:3.1:83 on the surface of the composite. ESCA analysis proved further that fluorine exists in a form of PTFE on the surface of the composite, and phosphorus and cobalt exist in forms of simple phosphorus and Co +3 , respectively. Tribology tests showed that the Co-P-PTFE composite has good tribological properties. The composite wear is 45 percent lower by weight loss than the coating of Co-P and 79 percent lower than 45# steel in dry conditions and 60 percent lower by weight loss than the composite of Ni-P-PTFE in oil.