ZrB2 and ZrB2-SiC powders have been produced by reducing ZrO2 and ZrSiO4 with B4C without using any furnace.Magnesium was added to the mixtures of (ZrO2+B4C) and (ZrSiO4+B4C).The reaction has been assisted by a floral...ZrB2 and ZrB2-SiC powders have been produced by reducing ZrO2 and ZrSiO4 with B4C without using any furnace.Magnesium was added to the mixtures of (ZrO2+B4C) and (ZrSiO4+B4C).The reaction has been assisted by a floral thermite packed around the compacts.By introducing elemental Si into (ZrO2+B4C) mixture,composite powders of ZrB2-SiC formed.After leaching out MgO with suitable HCl water solution,the product was analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM).The effect of Si,B4C,and Mg on the extent of formation of ZrB2,ZrB2-SiC,and other phases has been studied.Formation of nano-sized ZrB2 and ZrB2-SiC composite powders was identified.The adaptability of the process for bulk production was examined.展开更多
A SiC/ZrSiO4？SiO2 （SZS） coating was successfully fabricated on the carbon/carbon （C/C） composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock r...A SiC/ZrSiO4？SiO2 （SZS） coating was successfully fabricated on the carbon/carbon （C/C） composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock resistance. The anti-oxidation properties under different oxygen partial pressures （OPP） and thermal shock resistance of the SZS coating were investigated. The results show that the SZS coated sample under low OPP, corresponding to the ambient air, during isothermal oxidation was 0.54% in mass gain after 111 h oxidation at 1500 ° C and less than 0.03% in mass loss after 50 h oxidation in high OPP, corresponding to the air flow rate of 36 L/h. Additionally, the residual compressive strengths （RCS） of the SZS coated samples after oxidation for 50 h in high OPP and 80 h in low OPP remain about 70% and 72.5% of those of original C/C samples, respectively. Moreover, the mass loss of SZS coated samples subjected to the thermal cycle from 1500 ° C in high OPP to boiling water for 30 times was merely 1.61%.展开更多
文摘ZrB2 and ZrB2-SiC powders have been produced by reducing ZrO2 and ZrSiO4 with B4C without using any furnace.Magnesium was added to the mixtures of (ZrO2+B4C) and (ZrSiO4+B4C).The reaction has been assisted by a floral thermite packed around the compacts.By introducing elemental Si into (ZrO2+B4C) mixture,composite powders of ZrB2-SiC formed.After leaching out MgO with suitable HCl water solution,the product was analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM).The effect of Si,B4C,and Mg on the extent of formation of ZrB2,ZrB2-SiC,and other phases has been studied.Formation of nano-sized ZrB2 and ZrB2-SiC composite powders was identified.The adaptability of the process for bulk production was examined.
基金Project supported by the Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center,ChinaProject(51205417)supported by the National Natural Science Foundation of China
文摘A SiC/ZrSiO4？SiO2 （SZS） coating was successfully fabricated on the carbon/carbon （C/C） composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock resistance. The anti-oxidation properties under different oxygen partial pressures （OPP） and thermal shock resistance of the SZS coating were investigated. The results show that the SZS coated sample under low OPP, corresponding to the ambient air, during isothermal oxidation was 0.54% in mass gain after 111 h oxidation at 1500 ° C and less than 0.03% in mass loss after 50 h oxidation in high OPP, corresponding to the air flow rate of 36 L/h. Additionally, the residual compressive strengths （RCS） of the SZS coated samples after oxidation for 50 h in high OPP and 80 h in low OPP remain about 70% and 72.5% of those of original C/C samples, respectively. Moreover, the mass loss of SZS coated samples subjected to the thermal cycle from 1500 ° C in high OPP to boiling water for 30 times was merely 1.61%.
