A rotary internal combustion engine and particularly an improved rotor construction for such engine and method of making is disclosed. A coating system is applied at least to the flank surfaces of the rotor which face the variable volume combustion chambers of the engine, the system serving to reduce heat flow to the oil lubrication system within the rotor and to quench heat build-up on the above surfaces to prevent pre-ignition. The engine is permitted to run at a somewhat higher operating temperature resulting in increased efficiency, better fuel consumption and reduction of emissions. In the method of construction, vaporizing means is employed to supply vaporizable material from two crucibles. The means can be controlled to deposit one or a mixture of said vaporizable materials. One crucible contains an adherent conductive metal and the other crucible contains an insulating medium. The vaporizing means is controlled to deposit a first layer consisting of the adherent conductive metal, a second layer consisting of a mixture of the insulating medium and adherent conductive metal, a third layer consisting essentially of an insulating medium, a fourth layer consisting essentially of a mixture of the adherent metal and insulating medium, and a fifth layer consisting of solely the adherent conductive metal.