STRESSES IN MULTILAYER COMBINATIONS OF SPUTTER DEPOSITED COATINGS OF NI, TI, TIC+NI, AND TIB2+NI ON CARBON-STEEL SUBSTRATES

When hostile abrasive conditions are encountered, surface protection in the form of hard erosion resistant coatings is required. TiC + Ni and TiB2 + Ni coatings with combinations of Ni and Ti interfacial coatings were deposited on carbon steel substrates by magnetically enhanced dc sputtering. Thicknesses of the erosion resistant coatings ranged from 8.0 to 12.0-mu-m and the thicknesses of the interfacial coatings ranged from 2.5 to 9.0-mu-m. The relationship between erosion resistance and stresses in the coatings were evaluated. Stress measurements were obtained using the bending beam method where stress is determined from the measured deflection of a cantilevered composite material type beam formed by the coating-substrate combination using the equivalent stiffness (EI) method to determine intrinsic, thermal, and shear stress components. Erosion resistance was measured by bombarding the surface of the TiC + Ni and TiB2 + Ni coatings with a high-velocity flow of hard alumina particles.