Wear Resistance of Titanium Boride Coated Titanium Alloy Against Alumina

Tuesday, September 25, 2007 - 11:20 AM

Wear Resistance of Titanium Boride Coated Titanium Alloy Against Alumina

C. D. Lee, N. M. Tikekar, K. S. R. Chandran, University of Utah, Salt Lake City, UT; A. Sanders, Ortho Development Corporation, Draper, UT

The tribological performance of titanium alloy (Ti-6Al-4V) ball bearings with a double layer coating (consisting of a monolithic TiB₂ layer combined with a TiB whisker layer) mated against alumina has been determined using ball-on-disk wear testing and compared to a 97% dense alumina ball. The friction and wear were measured using a load cell and optical measurement of wear spot diameters, respectively. The wear mechanisms were determined using scanning white light interferometry (SWLI), optical microscopy, and scanning electron microscopy (SEM). The borided ball showed a 40-fold reduction in wear compared to alumina and showed slightly lower friction values. The superior wear properties are attributed to the hardness and unique structure of the double layer TiB₂/TiB coating and the subsequent smoothness of the wear surface that emerges during wear testing. The wear mechanism was determined to be abrasive in nature for the boride coated balls, whereas the alumina balls exhibited grain fracture and removal. The improved tribological properties of Ti-6Al-4V with a double layer TiB₂/TiB coating make it a potential candidate for use as a material in biomedical devices with articulating surfaces such as total joint replacements.

Summary: A double layer consisting of a monolithic TiB2 layer and a TiB whisker layer was deposited on Ti alloy (Ti-6Al-4V) ball bearings. The tribological properties of the coating was tested and compared to those of alumina ball bearings.