Papers by Author: Q.M. Yuan

Abstract: In this paper, the performances of CBN abrasives with and without Ti coatings and their changes during heat treatment were investigated under the same conditions. The results showed that the single particle compressive strength and the impact toughness for CBN abrasives with Ti coatings were lower than these of CBN abrasives without Ti coating. Ti coating on the surface of CBN abrasive particles oxidized and formed TiO2 with discontinuous structure at above 650°C during the firing process. The poor oxidation resistance of Ti coating and the discontinuous structure of its oxidation product could not protect CBN abrasives from heat damage, therefore could not improve properties of CBN abrasives.

Abstract: The effect of microstructure on the wear resistance of two Al2O3 dispersed in ZrO2 matrix (ADZ) ceramics was investigated, Al2O3 dispersed in commercially co-precipitated 3mol% Y2O3-doped tetragonal zirconia polycrystal (CYADZ) and Al2O3 dispersed in mixed 3mol% Y2O3-doped tetragonal zirconia polycrystal (MYADZ). These materials were used as a pin sliding against a plate of polyurethane rubber (UR) in the presence of aqueous NaOH solution containing SiO2 as the abrasive medium at a sliding speed of 0.15m/s and a normal load of 100N. The results indicated that the CYADZ specimen had uniform microstructure and fine grain size, which accounted for its better abrasive wear-resistance than that of the MYADZ specimen with non-uniform microstructure and largely different grain sizes due to inhomogeneous distribution of Y2O3. The hardness and toughness of two ADZ specimens were close, but strength of the MYADZ specimen was lower than that of the CYADZ specimen, which indicated the defect was serious in the MYADZspecimen. The CYADZ specimen was characterized by plastic deformation and micro-ploughing, which the MYADZ specimen dominated by micro- cracking and brittle fracture.