The present claimed invention relates to a high emissive coating (300) applied to the surfaces (210) of certain components of an x-ray tube device (100). The coating (300) increases the ability of the surface (210) to radiate heat, thus improving cooling of the tube (100). More importantly, use of the emissive coating (300) allows heat to be radiated from component surfaces (210) before it contacts and damages heat sensitive components. A preferred embodiment discloses application of an emissive coating (300) to the surface (210) or a tube's rotor (200) so as to significantly reduce the amount of heat passing from the shaft into the heat-sensitive ball bearing assembly (212) connected to it. Preferred emissive coatings (300) include metal oxide compositions composed of titanium oxide and aluminum oxide. The coating (300) is applied to the tube component surface by plasma spray coating or similar techniques.