溶解法测定铝基复合材料中碳化硅增强体体积含量

对于金相显微镜下难以区分增强体和基体组织的铝基复合材料而言,国家标准方法GB/T 32496—2016难以准确测量铝基复合材料中的增强体体积含量。实验以HCl(1+1)、HF和H₂O₂为溶解液消解铝基体,再采用砂芯坩埚和滤纸两种方法收集SiC,采用溶解法测定铝基复合材料中SiC增强体体积含量。实验探讨了溶解液对SiC增强体的腐蚀行为。结果表明:依次加入10~20mL HCl(1+1)、3~5mL HF和3~6mL H₂O₂可将Al基体组织溶解完全。精密度试验表明,待测SiC体积含量的相对标准偏差(RSD)均不大于0.1%(n=9),能满足铝基复合材料中SiC体积含量的检测要求。相比砂芯坩埚抽滤法,滤纸法较经济且结果稳定。推荐采用滤纸法进行铝基复合材料中SiC体积含量测试。采用滤纸法分析铝基复合材料样品,测定值与理论值吻合良好。

Determination of volume fraction of silicon carbide reinforcement in aluminum matrix composites by dissolution method

For aluminum matrix composites that are difficult to distinguish between reinforcements and matrix structures by metallographic microscope, it is difficult to accurately measure the volume fraction of reinforcements in aluminum matrix composites by national standard method (GB/T 32496—2016). Dissolution method was applied to the determination of volume fraction of SiC reinforcement in aluminum matrix composites. The aluminum matrix was firstly digested with HCl (1+1), HF and H₂O₂. Then SiC reinforcement was collected by glass filter crucible and quantitative filter paper, respectively. The corrosion behavior of the dissolving solution on SiC reinforcement was investigated. The results showed that aluminum matrix could be completely dissolved by adding 10-20mL HCl (1+1), 3-5mL HF and 3-6mL H₂O₂ sequentially. The precision results showed that the relative standard deviation (RSD) were not more than 0.1% (n=9), which could satisfy the determination demand of SiC volume fraction in aluminum matrix composites. The result of filter paper method was more economical and stable than that of glass filter crucible suction method. The filter paper method was recommended to determine SiC volume fraction in aluminum matrix composites. The analytical values of the aluminum matrix composite sample analyzed by filter paper method were in agreement with the theoretical values.