Al-B4C复合材料在硼酸溶液中腐蚀机理研究

采用硼酸溶液模拟乏燃料贮存水池环境，研究Al-B₄C复合材料在其中的腐蚀行为。用SEM、EDS观测腐蚀试样的微观形貌，用XRD测试腐蚀前后试样的物相，并测试腐蚀过程中试样的干重。结果表明：材料中的Al是引起腐蚀的主要因素；0~500 ppm硼酸溶液中，试样腐蚀增重，在表面生成斜晶结构的Al(OH)₃氧化膜，对材料起一定保护作用；2 500 ppm硼酸溶液中，试样腐蚀增重，在表面沉积非晶结构的Al(OH)₃絮状腐蚀产物；10 000~25 000 ppm硼酸溶液中，试样腐蚀失重，表面局部微小区域可观察到龟裂和腐蚀“坑”生成。材料抗腐蚀性能随溶液硼酸浓度的增加而降低，欲提高材料抗腐蚀性能，需对其进行表面保护处理。

Corrosion Mechanism of Al-B4C Composite Materials in Boric Acid

A boric acid solution was used to simulate the environment of actual spent fuel storage.The corrosion behaviors of Al-B4C composite materials in boric acid solutions were investigated.The microscopic morphology was observed by SEM and EDS.The phases of samples before and after the corrosion tests were measured by XRD and the dry weight of the samples was also measured.The results show that the corrosion is caused by aluminum in the Al-B4C composite;a dense layer of Al(OH)3 is formed after corrosion test in boric acid solution at 0 to 500 ppm and the samples gain weight after corrosion test;an amorphous Al(OH)3 sediments with wadding structure are found after corrosion in boric acid solution at 2 500 ppm and the samples also gain weight;some local areas appeared chapped and the corroded pits can be observed after corrosion in boric solution at 10 000 to 25 000 ppm and the samples lost weight.The corrosion resistance decreases with the increasing of concentration of boric acid.In order to improve the corrosion resistance,it is necessary to make a surface protection on Al-B4C composite.