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A predominance area diagram for the Zr-Si-C-O system at 1773 K was plotted according to correlative thermodynamic data.β-SiC/ZrO2 composites were prepared based on the phase diagram by carbothermal reduction of zircon(ZrSiO4) in argon atmosphere.Zircon and carbon black were mixed according to the C/ZrSiO4 mass ratio of 0.2,and with 0,1wt% and 2wt% extra addition of La2O3.Phase evolution of the mixture was investigated at 1723-1803 K by X-ray powder diffraction,and the microstructure of the product prepared at 1803 K for 4 h was examined by scanning electronic microscope.The results show that the decomposition of ZrSiO4 and the formation of β-SiC can be promoted by increasing the heating temperature and adding La2O3.The β-SiC/ZrO2 composites can be prepared at 1803 K for 4 h in a mixture of zircon,carbon black and La2O3,and the contents of β-SiC and m-ZrO2 in the product sample with 2wt% La2O3 reach the highest values of 10.8wt% and 89.2wt%,respectively.The crystal size of the products is about 200 nm.
A predominance area diagram for the Zr-Si-CO system at 1773 K was plotted according to correlative thermodynamic data. Β-SiC / ZrO2 composites were prepared based on the phase diagram by carbothermal reduction of zircon (ZrSiO4) in argon atmosphere. Zircon and Carbon black were mixed according to the C / ZrSiO4 mass ratio of 0.2, and with 0, 1 wt% and 2 wt% extra addition of La2O3. Phase evolution of the mixture was investigated at 1723-1803 K by X-ray powder diffraction, and the microstructure of the product prepared at 1803 K for 4 h was examined by scanning electronic microscope. The results show that the decomposition of ZrSiO4 and the formation of β-SiC can be promoted by increasing the heating temperature and adding La2O3. The β-SiC / ZrO2 composites can be prepared at 1803 K for 4 h in a mixture of zircon, carbon black and La2O3, and the contents of β-SiC and m-ZrO2 in the product sample with 2 wt% La2O3 reach the highest values of 10.8 wt% and 89.2wt%, respectively. Crystal size of the produ cts is about 200 nm.