Tribological Characteristics of Si3N4-HBN Ceramic Materials for Dry Application

Using air lubricants, wear tests of Si3N4-hBN composites with different hexagonal boron nitride (hBN) volume fraction sliding against Si3N4 ceramic were carried out on a MMU-5G type pin-on-disc tester. For comparison, Si3N4/Si3N4 pairs were also tested under the same conditions. The worn surfaces of specimens were observed under scanning electron microscope (SEM). Furthermore, the wear debris were analyzed by using X-ray diffraction (XRD). Wear debris layers are formed on the wearing surface when Si3N4-hBN composites slide against Si3N4 ceramic under air lubrication. In this situation, the friction coefficients are as high as 0.80-1.20 and the wear coefficients are above 10-5 mm3/Nm for all materials tested.