【摘要】 碳化硅是一种应用在高温工程中有希望的候选材料。目前,许多工作正致力于研究气体透平和其它工程中需用的强度高、抗氧化性优良的SiC烧结体。 本文研究了添加剂（B₄C、C）和其它工艺参数对热压SiC的烧结性状和机械性能的影响。同时也研究了不同温度、不同时间、湿氧条件下的氧化增重和强度变化。 研究所得的结果如下: （1）B₄C和C是热压α-SiC达到致密必不可少的添加剂。达到最高密度的B₄C和C的最低限量分别为0.5wt％。 （2）热压SiC的室温抗弯强度约为500MN/m²,且从室温到1400℃高温强度都几乎不变,高温时略有升高。另外,强度值似乎与碳的添加量（直到3wt％）无关。 （3）添加1wt％B₄C和3wt％C的SB₁C₃组成（热压条件是2050℃、保温45min、压力40MN/m²）,其性能是:密度3.17g/cm³,室温强度480MN/m²、热膨胀系数4.6×10^-6℃^-1,洛氏硬度HRA93.5。 （4）直到1280℃,掺B₄C和C的SB₁C₃组成的抗氧化性是非常优良的,氧化速率与时间呈抛物线关系,氧化后的室温强度也是基本不变的。更多还原

【Abstract】 Silicon carbide is a highly feasible material for high temperature engineering applica-tions. Recently extensive work has been directed to high strength and high oxidation resi-stant SiC bodies for gas turbine and other engineering applications. This paper describes the effects of additatives （B₄C and C） and other processing para-meters on the sintering behaviour and mechanical properties of hot-pressed SiC, includingthe weight gain and the change of strength after oxidation under various temperatures andwet-oxygen conditions. The experimental results can be summarized as follows: （1） Boron carbide and carbon are jointly necessary as additives for obtaining hot pres-sed SiC of high density. The lower limit of B₄C or C addition required to give maximumdensity is about 0.5% respectively. （2） The strength of hot-pressed SiC is about 500MN/m² which remains almost unchang-ed from room temperature up to 1400℃ and is nearly irrelevant to carbon content up to3%. As fracture at high temperature has been assumed to be governed by grain boundaryphases, the preservation of strength at high temperature rules out the possibility of forma-tion of low melting compounds at grain boundary, more so for the fact that the strengthof SiC has been observed even to increase slightly at higher temperatures. （3） The sample of SiC containing 1% B₄C and 3% C hot pressed at 2050℃ for 45 minutesunder pressure of 40 MN/m² possesses the following properties: density 3.17g/cm³, bendingstrength at room temperature 480 MN/m², coefficient of thermal expansion 4.6 10^-6℃^-1,hard-ness HRA93.5. （4） The oxidation resistance of hot-pressed SiC is quite good under 1280℃. The rateof oxidation varies with time according to a parabolic function. After oxidation thestrength of SiC under room temperature remains almost unchanged.更多还原