Method of depositing composite metal coatings containing low friction oxides

Method of depositing a metal base coating containing a self-lubricating oxide phase and one or more wear resistant phases, by: preparing at least one light metal substrate surface to be essentially oxide-free and in a condition to adherently receive the coating, plasma spraying a supply of metal (M) powder particles onto the substrate surface to produce a composite coating of such metal (M) and an oxide (MOx) of such metal that has the lower oxygen content of any of such metal's oxide forms, the plasma being formed by introduction of a primary plasma gas through an electric arc/electromagnetic field to ionize the primary gas as a plasma stream which stream envelopes each particle of the introduced powder, the powder particles being introduced to the plasma stream by an aspirating gas and being melted or plasticized substantially only at a surface region of each particle by the heat of the plasma; the primary plasma gas being constituted of a reactively oxide-neutral gas, but including a reducing gas component particularly when the oxide form of such powder is less than 90% MOx, and the aspirating gas being constituted of a reactively oxide-neutral gas, but including an oxidizing component if the volume content of the MOx form of the powder is less than 5% or it is desired to increase the volume of the oxide form MOx of the powder.