Accession Number : ADA298084

Title :   Nondestructive Evaluation of Sputtered-Deposited Tantalum Carbide Refractory Coatings.

Descriptive Note : Final rept.,

Corporate Author : ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS

Personal Author(s) : Lee, S. L. ; Heffernan, W. J. ; Walden, J.

PDF Url : ADA298084

Report Date : MAR 1995

Pagination or Media Count : 27

Abstract : Desirable characteristics of refractory coatings for future projectile launchers include high wear resistance, high melting point, hardness, electrical conductivity, good adhesion, thermal stability, and high plasma resistance properties. Sputtered tantalum and tantalum compounds, such as tantalum nitride and tantalum carbide are being considered as future coatings to endure the high pressure, high temperature, and aggressive chemical environment of the bore. In this work, tantalum and tantalum carbide were reactively sputtered deposited from argon plasmas containing methane. Nondestructive x-ray diffraction analysis determined that body-centered-cubic (bcc) tantalum was deposited at methane concentrations below 20 percent, face-centered-cubic (fcc) tantalum carbide was deposited at methane concentrations above 25 percent, and a mixture of tantalum and tantalum carbide was deposited at the transitional 22 percent methane concentration. Coating composition, crystalline structure, particle size, preferred orientations, deposition rate, Knoop hardness, and temperature coefficient of resistivity are sensitive functions of percentage methane concentration in the sputtering-deposited process. jg p.3

Descriptors :   *NONDESTRUCTIVE TESTING, *PROJECTILES, *LAUNCHERS, *SPUTTERING, *REFRACTORY COATINGS, *TANTALUM CARBIDES, PARTICLE SIZE, CRYSTAL STRUCTURE, HIGH RATE, HIGH TEMPERATURE, PLASMAS(PHYSICS), RESISTANCE, ADHESION, X RAY DIFFRACTION, RATES, REACTIVITIES, THERMAL STABILITY, HIGH PRESSURE, SENSITIVITY, ELECTRICAL CONDUCTIVITY, NITRIDES, MIXTURES, CHEMISTRY, COATINGS, DEPOSITION, METHANE, TEMPERATURE COEFFICIENTS, ARGON, COMPOSITION(PROPERTY), MELTING POINT, HARDNESS, CONCENTRATION(CHEMISTRY), DIFFRACTION ANALYSIS, WEAR RESISTANCE, TANTALUM COMPOUNDS.

Subject Categories : Coatings, Colorants and Finishes
      Inorganic Chemistry
      Ammunition and Explosives

Distribution Statement : APPROVED FOR PUBLIC RELEASE