Study on Oxidation Resistance of Natural Graphite Electrode Impregnated with Phosphate Solution

Three natural graphite samples,with electrodes being impregnated with three different phosphate solutions respectively under normal pressure and at room temperature,were burned for an hour at five temperature points.Their rates of oxidation mass loss were determined to find out the phosphate impregnant with the best oxidation resistance.Moreover,the effects of the variation of impregnant concentration on the oxidation resistance of the samples were investigated by changing the amount of phosphate.The morphologies and oxidation resistance of the impregnated and unimpregnated samples were observed by SEM and thermal analysis.The results showed that the initial mass loss temperature of the samples impregnated with 2#(H3PO4+Na2HPO4·12H2O) were 50 ℃ higher,and the weight loss rate at 900 ℃ was 37% lower than those of the unimpregnated samples.