Influence of Y 2O 3 contents on sintering and mechanical properties of B 4C-Al 2O 3 multiphase ceramic composites

摘要

In this study, B4C-Al2O3multiphase ceramic composites were prepared by spark plasma sintering (SPS) and Y2O3was used as a sintering aid. Results show that in the range of 1350–1500°C, nearly full dense B4C-Al2O3multiphase ceramic composites with a high densification rate (4×10?3/s) can be fabricated. Addition of Y2O3can lead to reduce activation energy of densification and plastic flow mechanism during sintering of the ceramic composites. At the same time, Y2O3can react with Al2O3to form liquid Y3Al5O12, which can effectively reduce the densification temperature of the ceramic composites. With the increase of Y2O3content, the temperature was lowered from 1500 °C to 1350 °C. When the Y2O3content was 1.0 vol.%, relative density, hardness, fracture toughness, and flexural strength of the ceramic composites were 98.60%, 23.75 GPa, 4.89 MPa?m1/2, and 464.96 MPa, respectively. The toughening mechanism of the ceramic composites followed particle toughening and micro-crack toughening. The internal grains of the composites were tightly bonded, they were mainly fractured in the transgranular form and the cross section was relatively rough with a high bending strength of 450 MPa.