Tribology in superplastic forming processing of 3Y-TZP/Al2O3 ceramic at elevated temperatures

Superplastic forming processing of ceramic materials at high temperatures and high pressure puts forward very high requests to moulds and lubricants, at which conditions seeking for appropriate lubricants is one of important preconditions in the superplastic forming of ceramic materials. Using ring compressive testing, lubricities of hexagonal boron nitride in superplastic compressive forming processing of 3Y-TZP/Al2O3 ceramic composite at elevated temperatures were investigated. Theoretical curves of friction factor were drawn according to upper bound method. Ring compressive tests were adopted at temperature of 1400 degrees C-1600 degrees C. The results indicate that when BN is used, friction factor is about 0.4, meanwhile friction factor don't have great changes with higher temperature and increasing strain rate. X-ray diffraction shows that under high temperature and high pressure no boron nitride converts to cubic phase, which remains at room temperature.