Patent ID: 7838083
Filing Date: 2010-11-23
Classification: C23C,F05B

Abstract:
1. A process for coating a metallic substrate with alpha-phase alumina, comprising steps of: a) preheating a metallic substrate to at least 500° C. in a vacuum chamber by using a heated thermal cage surrounding the substrate; b) exposing the pre-heated substrate to a plume of alumina evaporated from an alumina ingot heated with an electron beam; c) depositing alumina from the plume on to the substrate while simultaneously irradiating the deposit with a collimated beam of energetic ions; thereby transforming the deposited alumina into alpha-phase alumina; and d) stopping the process when a desired thickness of the alpha-phase alumina has been reached, thus forming an alpha-phase alumina coating; wherein the thickness of the alpha-phase alumina coating is between 0.1 and 2.0 microns; wherein the substrate temperature does not exceed 800 during the coating process; wherein the collimated beam of energetic ions comprises argon ions with an energy between 200 and 600 eV; wherein the process does not require performing a post-coating anneal at a temperature of at least 1100 for 2 or more hours in order to transform the deposited alumina into alpha-phase alumina; wherein the process does not comprise exposing the substrate to a plasma glow discharge during the depositing of the alumina; and further comprising using the collimated beam of energetic ions to sputter-clean the substrate prior to depositing the alumina.