DRY SLIDING WEAR BEHAVIOR OF HARD CHROMIUM AND

MARCELO J.L. GINES; W. TUCKART; SEBASTIÁN ABRAHAM

Copacabana, Rio de Janeiro

Congreso; First International Brazilian Conference on Tribology ? TriboBr-2010,; 2010

ABM

This study addresses the dry sliding wear behavior of different hard chromium coatings and they are compared to mono and multilayered nickel-based coatings which could be a replacement of conventional hard chromium coatings. Both hard chromium and nickelbased coatings were obtained over a substrate of AISI H13 steel by electroplating from hexavalent chromium and nickel-tungsten-phosphorus aqueous solutions, respectively. Monolayer hard chromium coatings were prepared by changing current density, temperature, and bath composition (proprietary non-fluoride catalyst). Mono and multilayered nickel-based coatings were prepared by using various current densities leading to different structure and composition, and consequently distinct mechanical properties. Scanning electron microscopy and X-ray diffraction were employed to assess the morphology and microstructure of the coatings. According the wear test results, nickel-based coatings were less prone to wear than hard chromium coatings even though the latter are harder (hard chromium: 900-1100 HV; nickel-based: 500-600 HV). This behavior might be attributable to different wear mechanisms: abrasive wear type plowing for nickel-based coatings and adhesive wear for hard chromium coatings.