Method and device for forming porous ceramic coatings, in particular thermal barrier coatings, on metal substrates

摘要

Two different powders, one ceramic and the other of polymer particles, are fed separately into a jet of plasma of a conventional torch of a plasma spraying device by means of separate supply devices having respective powder injectors. The injection parameters of the two powders are established independently to achieve effective fusion of the ceramic particles and prevent complete combustion of the polymer particles. More specifically, the ceramic powder is injected along the axis of the jet of plasma, while the polymer powder is injected into a peripheral portion of the jet, at a predetermined distance from the jet axis, so that some of the polymer particles are incorporated in the ceramic coating deposited on a component for coating; and the polymer is subsequently removed by medium-temperature heat treatment to leave a porous ceramic coating with excellent thermal insulation properties.