Characteristic comparison of coating metal on cenospheres by chemical method and magnetron sputtering method

Metal coated cenospheres have been widely used in industries. Different coating method can get different characteristic metal film. The metal film on the cenospheres by chemical coating method appears not very smooth, uneven, with hill-like metal pile up on the surface. There are some uncoated spots on the surface. The metal film is not tightly adhere on the cenospheres and is apt to peel off from the surface. However, the metal film gained by magnetron sputtering is compact, smooth, even and no uncoated spot. The film has good affinity to the cenosphere surface. The film does not separate with cenospheres even when the cenospheres are crushed. Both of the metal films give the same XRD patterns. It means that the property of metal film by these two methods is the same. The chemical coating needs a complex process and tends to pollute the environment but it is suitable to ultrafine powder coating (the particle size can be less than 2 μm). The magnetron sputtering method is environmentally friendly and can coat film quickly, but this method needs specially designed equipment and it is hard to coat ultrafine powders. If the particle size is less than 30 μm, the coating process is hard to be carried on.