Ceramic coatings for high temperature corrosion resistance by laser processing

Ceramic coatings have been deposited on inclined metallic substrates; the silica powder was fed into the focus of the beam which was positioned above the substrate. This configuration was employed to reduce the depth of substrate melting whilst supplying adequate energy to the ceramic powder to give complete melting as the substrate and ceramic have a large difference in melting points. Important parameters for characterisation of the coatings produced included power, specific energy, traverse speed and interaction time. Surface analytical techniques were employed to examine the overlayers produced. Corrosion protection was assessed in air and also in a coal gasifier heat exchanger environment.