The Preparation Of High Temperature Oxidation Resistance Of Flexible Graphite And Performance Research

Flexible graphite has the characteristics of low stress relaxation rate, corrosion resistance, radiation resistance, high temperature resistance and other excellent properties, which are widely used in petrochemical, automotive, nuclear power and other fields. As a sealing material, the easy oxidation of flexible graphite under the condition of high temperature and oxygen enrichment of weightlessness disadvantages limits the scope of its use. Based on flexible graphite as the research object, this paper adopts the impregnation method for the high temperature oxidation resistant flexible graphite; and using Arrhenius equation to predict the life of high temperature oxidation resistant flexible graphite; at the same time, the change rules of density, tensile strength, compression resilience and sealing performance of high temperature oxidation resistant flexible graphite were studied by experiments. The main contents and conclusion are as follows:(1) In this paper, with phosphate, potassium phosphate monobasic and sodium tetraborate as the main reagent of impregnating solution, and through the orthogonal experiment method to determine the optimum process conditions of impregnation liquid:40 ml distilled water, sodium tetraboratel2 g,12 g potassium phosphate monobasic and phosphoric acid 10 ml, impregnation time is 3 h; TG-DSC analysis showed that the impregnating solution formed a layer of oxidation resistance coating on the surface of the flexible graphite, and increased the oxidation resistance of flexible graphite.(2) Using Arrhenius equation to predict the life of high temperature oxidation resistant flexible graphite monomer material and flange fastening state, and the results are compared with extrapolated life. The result suggests that the precision of Arrhenius equation is better; under the same conditions, life of prepared high temperature oxidation resistant flexible graphite is 1.4 times of the domestic product,2.2 times of foreign products.(3) The basic properties of high temperature oxidation resistant flexible graphite sealing materials were studied by relative test standards. It is found that density of high temperature oxidation resistant flexible graphite is lower than pure flexible graphite; when dipping time is 3-4h, dipping solution concentration is 30%?40%, tensile strength of material is higher, larger than pure flexible graphite and close to domestic products, slightly better than foreign products; compression rate is larger than pure flexible graphite, higher than foreign products, slightly lower than domestic products; rebound rate is smaller than pure flexible graphite, closing to domestic products, slightly higher than foreign products.(4) The sealing performance test of high temperature oxidation resistant flexible graphite gasket was carried out, and discussed leakage rule of gasket. It is found that under low gasket pressure, sealing performance of high temperature oxidation resistant flexible graphite is superior to untreated flexible graphite gasket; sealing performance is not different from untreated flexible graphite gasket under high gasket pressure; Leakage of high temperature oxidation resistant flexible graphite gasket is mainly based on interface leakage, and the leakage of the main body is better than that of untreated flexible graphite gasket; Sealing performance of high temperature oxidation resistant flexible graphite gasket is better than that of foreign products, which is close to the domestic product.