Air-curing is usually applied to the polymer-derived SiC fibers and, as a result, oxygen is embedded to the material. An effective relationship between oxygen content of the SiC fibers and mass gain of their precursor...Air-curing is usually applied to the polymer-derived SiC fibers and, as a result, oxygen is embedded to the material. An effective relationship between oxygen content of the SiC fibers and mass gain of their precursor fibers was established. Results also showed that oxygen content has a great influence on the mechanical properties and excellent tensile strength is usually obtained at the oxygen content of 12%～13%, similar to the density of SiC fibers. Oxygen content has a positive effect on the ceramic yield, and thus, is good to the density and tensile strength; while, oxygen content is also negative to volume content of SiC phase and crystallization of the SiC fibers, and thus, detrimental to the density and tensile strength. Both of the two effects result in the peak behavior of the tensile strength of SiC fibers.展开更多
利用高温收缩测定设备,对含有不同结合氧的 β-SiC 粉末进行了无压烧结过程的动力学研究。测定了β-SiC 的烧结收缩曲线。计算出烧结收缩初期动力学级数 n 值分别为1/3和1/2.5。烧结收缩中期 n 值为1/1.6,可用 Coble 的中期模型来表达;...利用高温收缩测定设备,对含有不同结合氧的 β-SiC 粉末进行了无压烧结过程的动力学研究。测定了β-SiC 的烧结收缩曲线。计算出烧结收缩初期动力学级数 n 值分别为1/3和1/2.5。烧结收缩中期 n 值为1/1.6,可用 Coble 的中期模型来表达;并受晶粒生长的影响。活化能为543～669kJ/mol。展开更多
文摘Air-curing is usually applied to the polymer-derived SiC fibers and, as a result, oxygen is embedded to the material. An effective relationship between oxygen content of the SiC fibers and mass gain of their precursor fibers was established. Results also showed that oxygen content has a great influence on the mechanical properties and excellent tensile strength is usually obtained at the oxygen content of 12%～13%, similar to the density of SiC fibers. Oxygen content has a positive effect on the ceramic yield, and thus, is good to the density and tensile strength; while, oxygen content is also negative to volume content of SiC phase and crystallization of the SiC fibers, and thus, detrimental to the density and tensile strength. Both of the two effects result in the peak behavior of the tensile strength of SiC fibers.
文摘利用高温收缩测定设备,对含有不同结合氧的 β-SiC 粉末进行了无压烧结过程的动力学研究。测定了β-SiC 的烧结收缩曲线。计算出烧结收缩初期动力学级数 n 值分别为1/3和1/2.5。烧结收缩中期 n 值为1/1.6,可用 Coble 的中期模型来表达;并受晶粒生长的影响。活化能为543～669kJ/mol。
