INTERFACIAL MICROSTRUCTURE AND MECHANI-CAL PROPERTIES OF INDIRECT BRAZED GRAPHITE/COPPER JOINT

Graphite and metal composite structures were widely used in aerospace, electrical engineering and electronics. Because of its conveniences and less cost, brazing was widely used to bond graphite and metals. Due to the differences in microstructure, graphite was difficult to be wetted by traditional braze alloys. To improve the wettability of traditional brazing alloys on graphite, active brazing process and indirect brazing process were developed to braze graphite to metals. As to active brazing process, active elements (such as Ti, Cr, Zr) were added into traditional brazing alloys, a high brazing temperature, was essential to guarantee the reaction of active elements with graphite. However, the mechanical properties of metals will degrade under high temperature. Electroplating and chemical plating were the general techniques for indirect brazing process. The covered coating had a mechanical combination which decreased the joint strength, rather than metallurgical bonding with graphite. Therefore, in this work, a new metallization method was proposed. On the one hand, a metallurgical bonding was formed between metallization layer and graphite substrate. On the other hand, graphite could be brazed to metal at a relatively low temperature. Firstly, graphite was metalized by Ti-containing Sn0.3Ag0.7Cu metallization powder at 950°C *国家自然科学基金项目51405099和上海航天科技创新基金项目SAST2015045资助 收到初稿日期: 2015-09-25,收到修改稿日期: 2016-03-29 作者简介:付 伟,男, 1989年生,博士生 DOI: 10.11900/0412.1961.2015.00502 第734-740页 pp.734-740