Phase, Residual Stress, and Texture in Triode-Sputtered Tantalum Coatings on Steel

摘要

This work analyzes the unoptimized prototype triode-sputtered. 150 microns thick tantalum coatings deposited with a 2.5 microns niobium under-layer the bore of a large-diameter A723 steel cylinder. The coating was deposited for wear and erosion protection by Pacific Northwest National Laboratory. Our phase determination was based on X ray diffraction analysis, wavelength dispersive X ray fluorescence analysis, energy dispersive X ray analysis, and hardness and electrical resistivity measurements. Both X ray diffraction and radius-of- curvature methods were used to determine residual stresses. A locally developed high-resolution pole figure technique was used to perform texture analysis. The post-firing, debonded coating showed alpha-tantalum, preferred 110 orientation, high surface stresses, tantalum oxides, entrapped krypton sputtering gas, interstitial oxygen, and other impurities. The surface and subsurface pole figures revealed broadened poles and body-centered-cubic tantalum crystalline structure.