石墨(mo)的電阻率比(bi)銅和鋁(lv)都(dou)大。石墨(mo)的電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)率(lv)為:石墨(mo)(8~13)×10-6(Ω/m),銅(tong)的電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)率(lv)為1.7×10-8(Ω/m),鋁(lv)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)率(lv)為2.9×10-8(Ω/m),可以看(kan)出(chu)石墨(mo)的導電(dian)(dian)(dian)(dian)率(lv)比銅(tong)和(he)鋁(lv)都大。在相同的截面(mian)積和(he)長度的情況(kuang)下,石墨(mo)的直流(liu)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)是銅(tong)直流(liu)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)的588倍(bei),是鋁(lv)直流(liu)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)的344倍(bei)(取石墨(mo)電(dian)(dian)(dian)(dian)導率(lv)為10×10-6(Ω/m)),因此當通過相同電(dian)(dian)(dian)(dian)流(liu)時,石墨(mo)的電(dian)(dian)(dian)(dian)能損耗比銅(tong)和(he)鋁(lv)都大,輸電(dian)(dian)(dian)(dian)過程(cheng)中(zhong)造成發熱(re)嚴重的現(xian)象。自(zi)然界中(zhong)沒(mei)有純凈的石墨(mo),其中(zhong)往(wang)往(wang)含有SiO2、Al2O3、FeO、CaO、P2O5、CuO等(deng)雜質。這些雜質常以石英、黃鐵(tie)礦(kuang)、碳(tan)酸鹽等(deng)礦(kuang)物形式出(chu)現(xian)。此外,還有水、瀝青、CO2、H2、CH4、N2等(deng)氣體部分。這樣會造成石墨(mo)的導電(dian)(dian)(dian)(dian)性能不穩定,電(dian)(dian)(dian)(dian)導率(lv)變(bian)化相差較大。
常溫下石墨的耐氧化性能差,但隨著溫度的提高,氧化速度逐漸增加,石墨在應用過程中有消耗(以石墨電極為例)。電線電纜在通電運行中有溫升的出現,溫度升高促使石墨被氧化,影響電線電纜的穩定性。如果遇到輸電系統短路或者雷擊等惡劣環境,溫升更高,氧化加劇,對石墨的導電性有很大的影響。從而會影響電力系統的穩定性。
電氣(qi)工業中(zhong)所使用的石墨,對粒度和(he)品位要求(qiu)很高,對石墨的提(ti)純需(xu)要投入更多的設備和(he)技術。