Study On The Preparing Process And Adhesion Properties Of Surface Protective Coatings Of The Magnetic Refrigerant Material Gd

At room temperature, Gd is one of the important magnetic refrigerant materials in magnetic refrigerator, for it has large magnetocaloric effect , perfect toughness and processed easily. However ,it is easy to be corroded in the exchanging heat liquid of magnetic refrigerator during working, which affect its service life seriously.The work on four kinds of films, which were stainless steel lCrl8Ni9Ti, high pure Ti, Cu and Al, were coated on the surface of Gd by means of DC magnetron sputtering technology is described in this paper. All kinds of related properties including microscope, interface between films and Gd, compositions of the surface, and thickness of films were tested by SEM, SPM, EDX, XPS and other experimental devices. And then we studied the adhesion between the films and the substrate. As the result, the best parameters of the technology were achieved.The research results show that stainless steel films are growing as distributed islands which are gathered with atoms. The surface is rough during the film growing and the grains are like thin fibers. The depositing rates of the four kinds of films are seriously affected by the sputtering power density. Compared with the other three films , the join force between Cu and Gd is the weakest. The surfaces of the threekinds of the films are smooth and perfect, in which Al is the best and the interface joins strongly. The reasons for this are the matching properties and bonding type and wetting of films-substrates. While for the same partner of film-substrate, the adhesion is related with the parameters of sputtering. The research results show that the film of Al is the best of the four kinds of materials, for its good surface qualities, interface and adhesive property, which is potential to be used to promote the corrosion resistance of magnetic refrigerant materials Gd.