Process for converting a metal carbide to carbon by etching in halogens
AssigneeThe Board of Trustees of the University of Illinois
InventorsMichael J. McNallan, Daniel Ersoy, Yury Gogotsi
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Abstract
A process for the synthesis of carbon coatings on the surface of metal carbides, preferably SiC, by etching in a halogen-containing gaseous etchant, and optionally hydrogen gas, leading to (he formation of a carbon layer on the metal carbide. The reaction is performed in gas mixtures containing about 0% (trace) amounts to 100% halogen-containing gaseous etchant, e.g., Cl2, and about 0% to 99.9% H2 (hydrogen gas) at temperatures from about 100° C. to about 4,000° C., preferably about 800° C. to about 1,200° C., over any time range, maintaining a pressure of preferably about one atmosphere, to about 100 atmospheres.
Claims8
An improved bearing disposed as part of a mechanical device, said mechanical device including a solid part in frictional contact with said bearing such that there is relative movement between said solid part and said bearing when the mechanical device is being operated, wherein the bearing includes a bearing surface in relative movement with respect to said solid part, said bearing surface having enhanced wear and friction properties by contacting a metal carbide, at a portion of said metal carbide that forms said bearing surface with a halogen-containing gaseous etchant having a halogen-containing gas concentration sufficient to remove metal from the metal carbide surface, at a temperature, pressure and for a time sufficient to provide said bearing surface on said metal carbide, said bearing surface having a surface gradient of hardness and Young's modulus comprising an adherent, non-spalling, non-separable, disordered carbon layer having a Raman peak intensity ratio of ID/IG of 0.80 to 1.20, cross bonded between crystallite plates on the metal carbide and having a graphitized upper bearing surface.
Dependencies are inferred from the claim text.