放电等离子烧结制备非连续石墨纤维/Cu复合材料

Discontinuous graphite fiber/Cu composites fabricated by spark plasma sintering

以磨碎中间相沥青基石墨纤维和铜粉为原料,通过放电等离子烧结(spark plasma sintering,SPS)制备非连续石墨纤维/Cu复合材料,对石墨纤维表面进行镀钛金属化处理,以改善材料的界面结合状况。研究SPS工艺参数、铜粉粒度搭配、石墨纤维表面镀钛以及石墨纤维含量对石墨纤维/Cu复合材料致密度及热导率的影响。结果表明,将平均粒度为12和80μm的铜粉按1:2的质量比搭配,再与表面镀钛石墨纤维按1:1的体积比混合,采用35 MPa先加压后送热的加压方式,于895℃下进行放电等离子烧结,可获得致密度达99.6%、热导率为364 W/(m.K)的石墨纤维/Cu复合材料,是1种很有潜力的电子封装材料。石墨纤维表面镀覆的极薄Ti镀层,可使复合材料在二维平面方向上的热导率从196 W/(m.K)提高到364 W/(m.K)。

Discontinuous graphite fiber/Cu composites were fabricated by spark plasma sintering （SPS） technique using milled form of mesophase pitch-based graphite fibers and Cu powders as raw materials. Titanium was also coated onto the graphite fibers to optimize the quality of interracial bonding of the composites. The effects of SPS process parameters, Cu powder sizes matching, surface modification and volume fraction of graphite fiber on relative density and thermal conductivity of the composites were studied. The results indicate that the graphite fiber/Cu composites with relative density of 99.6% and thermal conductivity of 364 W/（m.K） can be obtained when the Cu powder consists of two groups of Cu powder with average particle size of 12 grn, 80 Ixm respectively and matched according to a mass fraction ratio of 1：2, volume fraction ratio of Cu powder and Ti-coated graphite fiber is of 1：1, and sintered at 895 ℃under 35 MPa pressure with providing pressure firstly and offering temperature subsequently by SPS method. The obtained composites are very potential materials for electronic packing. Furthermore, the application of the thin Ti coating onto the graphite fibers can enhance the in-plane thermal conductivity of the composites from 196 W/（m.K） to 364 W/（m.K）.