Effect of NiTi Addition on the Wear Resistance of YSZ Coatings

In this study, small fraction of NiTi (۵ wt%) was added to Yttria stabilized zirconia (YSZ) top coat to improve it sliding wear resistance. The measurement of width of wear tracks after wear tests under a ۱۵ N load for ۱۰۰ m sliding distances showed that the width of wear track in NiTi-YSZ coating is shorter than that in YSZ coating which depicts the higher wear resistance of NiTi-YSZ coating samples. It is believed that the higher H/E value and pseudoelasticity effect of NiTi are two important factors which improved the wear performance of applied coatings. Also, to evaluate the role of addition of a NiTi (۵ wt%)–YSZ buffer layer on the durability of YSZ coatings during wear operation, wear tests with a ۲۰ N normal load and with a constant frequency were conducted on coated samples. It was observed that the conventional YSZ coating cracked and delaminated after about ۶۰ m sliding distance. However, in samples which contain a NiTi (۵ wt%) –YSZ buffer layer delamination was not observed until ۱۰۰ m sliding distance which is attributed to the ability of NiTi for accommodation of interface stresses and hindering of premature delamination during wear test under higher loads.

Keywords:

Air plasma spraying (APS) , Yttria stabilized zirconia (YSZ) , NiTi , Wear