石墨纤维增强铝基复合材料表面稀土成膜过程

采用含稀土Ce盐的化学溶液浸泡工艺在石墨纤维增强铝基(Gr/Al)复合材料表面制备无毒、无污染稀土耐蚀膜层,并对不同时间稀土Ce盐在Gr/Al复合材料表面的成膜情况进行研究.铝基体和石墨纤维表面均覆盖稀土膜层,此类稀土膜呈现"干泥"状,覆盖于Gr/Al复合材料表面.EDS面扫描结果表明:Al、O、C、Si、Ce和Mg是组成膜的主要元素;成膜30 min,稀土Ce质量分数达14.44%;成膜120 min,稀土Ce质量分数增加到47.48%.通过对其成膜过程进行研究,提出了膜层微裂纹的形成机制,其电化学成膜机理符合"微阴极成膜机理".由于稀土转化膜的存在,腐蚀过程中析氢和吸氧反应均受到抑制,同时还抑制阳极反应的发生.

Process of rare earth conversion coating on the surface of graphite fiber reinforce-ment aluminum matrix composites

A Ce conversion coating,which is non-toxic and non-pollution,was prepared by chemical dipping immersion treatment on graphite fibers reinforce aluminum(Gr/Al) composite surface.It is shown that the graphite fiber and aluminum alloy surfaces both are coated by the Ce conversion coating,and the microstructure of the coating is dried-mud-like.Energy dispersive spectroscopy(EDS) indicates that the major elements distributing on the coating are Al,O,C,Si,Ce,and Mg, and the mass fraction of Ce is 14.44wt% after coating for 30 min but increases to 47.48wt% after coating for 120 min.The formation mechanism of coating micro-cracks was put forward.The micro-cathodic formation mechanism can explain the characters of the coatings.The Ce conversion coating becomes a barrier of O2 diffusion and electron transmitting,and oxygen absorption and hydrogen separation were both inhibited.