Characteristic comparison of metal films coated onto the cenosphere by chemical and magnetron sputtering methods

Metal-coated cenospheres have been widely used in industries. Different coating methods result in different characteristic metal films. The metal film on the cenosphere by chemical coating does not appear to be very smooth, exhibiting metal piled up and pin holes on the surface and leaving some spots uncoated. Meanwhile, the metal film is not tightly absorbed onto cenospheres and is easy to peel off. However, the metal film prepared by magnetron sputtering is compact, smooth and without pin holes. The film has good affinity to the cenosphere surface. Such films do not separate with it even when the cenosphere is crushed. Both the metal films give the same XRD patterns, indicating that the crystal structure of the metal films by these two methods is the same. Chemical coating is a complex process and harmful to the environment, but it fits ultrafine powder coating (the particle size can be less than 2μ). The magnetron sputtering method is environmental friendly and works quickly, but this method requires specially designed equipment and does not work for ultrafine powders. If the particle size is less than 30μ, the coating process is hard to carry on.