碳源对反应烧结碳化硅性能的影响

Effects of Carbon Sources on Properties of Reaction-Bonded Silicon Carbide

以炭黑和石墨为碳源,控制碳添加量为10%(质量分数,下同),研究了不同炭黑、石墨比例对反应烧结碳化硅性能的影响。结果表明,当炭黑添加量为4%、石墨添加量为6%时,反应烧结碳化硅的力学性能较佳,此时抗弯强度为251.7 MPa,断裂韧性为4.29 MPa·m^(1/2)。通过XRD检测及对XRD谱进行Rietveld精修,分析发现炭黑添加量为4%、石墨添加量为6%的反应烧结碳化硅中的游离Si含量为24.44%(质量分数),而石墨添加量为10%的反应烧结碳化硅中的游离Si含量为28.57%(质量分数),相比前者游离Si含量较高,减少游离Si的含量可以提高反应烧结碳化硅的力学性能。

The carbon black and graphite were used as carbon sources to fabricate reaction-bonded SiC,and the total content of carbon sources was 10%(mass fraction,the same below).The effects of different ratios of carbon black and graphite on properties of reaction-bonded SiC were investigated.The results show that the reaction-bonded SiC with 4% carbon black and 6% graphite has good mechanical properties,the flexural strength and fracture toughness reach to 251.7 MPa and 4.29 MPa·m^(1/2).The mineral composition of reaction-bonded SiC was measured by XRD,the Rietveld simulation results of XRD patterns were adopted to measure phase content.The free Si content in reaction-bonded SiC with 4% carbon black and 6% graphite is 24.44%(mass fraction).The free Si content in reaction-bonded SiC with 10% graphite reaches to 28.57%(mass fraction),which is higher than that of the former.The decrease of free Si contributes to the improvement of mechanical properties of reaction-bonded SiC.