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什么是碳化硅
钱柜娱乐开户   发表时间:[2010-04-16 00:01]

 

什么是碳化硅

     碳化硅是由碳原子和硅原子以共价性键结的唯一化合物。碳化硅未曾在天然矿物中发现,属于人造的矿物。碳化硅是SiO2粉和碳粉在高温下还原反应生成,碳化硅分子式为SiCSiC是典型的共价链结合的化合物,它有α和β两种晶型,即立方形和六方形,立方形称为β-SiC,是在1800~2000℃形成;六方形则称为α-SiC,是在2000℃以上形成的。

    碳化硅在大气压力下的分解温度为2700℃。α-SiC的理论密度是3.18 g/cm,莫氏硬度约在9.2~9.3之间。碳化硅耐高温,与强酸、强碱不起反应,导电性及导热性好,具有很强的抗辐射能力。用碳化硅粉直接升华法可制得大体积和大面积的碳化硅单晶,用碳化硅单晶可生产绿色或蓝色发光二极管、场效应晶体管、双极形晶体管。用碳化硅纤维可制成雷达吸收材料,在军事工业中前景广阔。

    碳化硅精细微粉试生产碳化硅陶瓷的理想材料,碳化硅陶瓷具有优良的常温力学性能,如高的抗弯强度、优良的耐腐蚀性,非常高的抗磨损以及低的摩擦系数。由于碳化硅优异的物理及化学性能,使其在石油、化工、微电子、汽车、航空航太、雷射、原子能、机械、冶金等行业中获得广泛运用,如砂轮、喷嘴、轴承、密封件、燃气轮机动静叶片、发动机部件、耐火材料等。

  

物理性质

性质················································································碳化硅

密度(g/cm^3··························································· 3.18

热传导率(W/m·℃)(600°K····························0.335

热膨胀系数(10^-6cm/℃)········································ 5.12

微硬度(kgf/mm^2·················································· 2300

比热(J/kg·K·························································· 700

弹性系数(GPa·························································410

抗拉强度(MPa························································400

抗压强度(MPa······················································· 3900

抗折强度(MPa························································550

破裂韧性(MPa·m^1/2·······································  4.6

波尔松比 ····································································  0.19

熔点或分解点(·················································· 2700

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