含铍碳化硅纤维的耐高温抗氧化性能研究

High-temperature Resistance and Oxidation Resistance Performance of SiC Fibers Containing Beryllium

长期以来,氧的存在一直被认为是降低碳化硅纤维耐高温性能和热稳定性的主要因素。实验表明,引入Be可以提高含氧量相对较高的SiC_(f)的热氧化稳定性。通过化学分析,计算出含铍碳化硅纤维(SiC_(f)(OBe))的分子式为SiC_(2.16)O_(0.28)Be_(0.02)H_(9.39)。X射线衍射结果表明,SiC_(f)(OBe)主要由晶粒尺寸为1.5 nm的β-SiC、SiC_(x)O_(y)和石墨碳组成。在氩气氛下于1400℃煅烧2 h后,SiC_(f)(OBe)的平均抗拉强度为1.2 GPa,提高了70%,在1300℃的空气中热处理2 h时,SiC_(f)(OBe)的强度保持率可达50%,而普通SiC_(f)仅保持20%。

The presence of oxygen has long been considered to be the main factor for the reduction in antioxidation capability and thermal stability of silicon carbide fibers(SiC_(f)).Herein,we demonstrated that the introduction of beryllium can increase the thermo-oxidative stability of SiC_(f) with relative high content of oxygen.According to chemical analysis results,formula of the SiC_(f) fibers containing beryllium(SiC_(f)(OBe))was calculated to be SiC_(2.16)O_(0.28)Be_(0.02)H_(9.39).X-ray diffraction results indicated that the SiC_(f)(OBe)consisted mainly ofβ-SiC with an average grain size of 1.5 nm,along with SiC_(x)O_(y) and graphite carbon.After sintering at 1400℃for 2 h in Ar,the SiC_(f)(OBe)exhibited an average tensile strength of 1.2 GPa,with an increase by 70%.After annealing at 1300℃for 2 h in the air,the SiC_(f)(OBe)still had strength retention of 50%,much higher than that(20%)of the common SiC_(f).