Abstract: The apparatus comprises a plasma torch capable of an output speed of at least 100 m/s, a fine powder distributor, and a substrate holder which can be heated electrically and cooled by water, which is at an adjustable distance from the torch, and which is movable in two transverse directions at adjustable speeds. The method consists in starting from ceramic having a low roughness CLA and from powder having a narrow granulometric distribution over an average value of at most 10 .mu.m, and projecting the melted powder onto the substrates kept at a regulated temperature and subjected to the said transverse movements.