The present invention concerns a microcomposite powder comprising: flat graphite particles G.sub.LP having sides from 50 to 1000 .mu.m and a thickness from 5 to 50 .mu.m, consisting of agglomerates of more elementary graphite particles joined together and superimposed so that their principal planes are mutually parallel, said particles being covered with particles of a fluoropolymer from 0.1 to 0.5 .mu.m in size.