镁合金回收用坩埚失效原因分析

FAILURE ANALISIS OF CRUCIBLE USED FOR RECYCLING OF MAGNESIUM ALLOYS

镁合金回收静置炉坩埚在使用3个-4个月后，坩埚底壁厚减薄严重过早报废，用ICP-AES和金相显微镜对坩埚底物质观察、分析用SPARK发射光谱仪对坩埚中不同深度镁合金液体成分进行分析，结合生产制程分析其失效原因。结果表明，由于沉降作用，在坩埚底部容易形成一层含铝、锰、铁金属间化合物的富铝层，富铝层很容易和坩埚基体发生反应，生成硬脆的金属间化合物；金属问化合物的不断剥落，使得坩埚基体有效壁厚减小很快，最终导致坩埚提前报废。

Crucible of holding furnace used in the magnesium recycling scrapped after commissioning for 3-4 months,due to thinning too much of the bottom part. The substance sticking to the bottom of crucible was analyzed with ICP-AES and observed with optical microscope, the magnesium melt composition at different depths was also analyzed using an emission spectrometer. The mechanism is that due to density difference,the substances generated in the recycling process drop onto the bottom of the crucible, resulting in a layer with high content of aluminum, manganese and iron on the bottom. Such a layer is active to react with the crucible material,generating a hard and brittle layer of inter-metallic compound. The scaling and spal- ling of the compound results in thinning of the crucible substrate,progrssively causing the failure.