Accession Number : AD0694180

Title :   ZIRCONIUM AND NIOBIUM CARBIDE COATINGS ON NIOBIUM, TANTALUM, MOLYBDENUM, AND TUNGSTEN,

Corporate Author : FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO

Personal Author(s) : Burykina,A. L.

Report Date : 05 MAY 1969

Pagination or Media Count : 12

Abstract : Several methods of obtaining ZrC and NbC coatings on refractory metals were investigated. The method of obtaining ZrC and NbC coatings, involving deposition of a Zr or Nb layer on a Mo, Nb, or W sutstrate with diffusion impregnation from a solid phase using NH(subscript 4)Cl activation agent and subsequent carburizing at 1300-1700 degrees C for 0.5-5 hr., was found to be unsatisfactory because the diffusion impregnation of Nb, Mo, and W substrates proceeded very slowly, and led to the formation of solid solutions of the metals on the substrate surfaces. This made it almost impossible to obtain sufficiently thick layers of pure Nb or Zr on the surface of Mo, Nb and W substrates. Satisfactory Nb coating on Mo and W substrates were obtained by vapor deposition with an electron beam unit. Dense, strongly adhering niobium coatings with a porosity of less than 5 percent and a microhardness almost equal to that of pure Nb, were obtained in 2 hr on substrates at 500-600 degrees C. Attempts to obtain Zr coatings by the same method were unsuccessful. In obtaining ZrC and NbC coatings by vacuum sintering of degassed Nb, Ta, Mo and W specimens coated with a mixture of bentonite with carbide powder, satisfactory NbC coatings were obtained on Ta; in all other cases the reaction between the carbide powder and substrate resulted in the formation of intermediate phases.

Descriptors :   (*REFRACTORY METALS, *REFRACTORY COATINGS), CARBIDES, ZIRCONIUM COMPOUNDS, NIOBIUM COMPOUNDS, MOLYBDENUM, NIOBIUM, TANTALUM, DEPOSITION, USSR

Subject Categories : Coatings, Colorants and Finishes

Distribution Statement : APPROVED FOR PUBLIC RELEASE