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采用二苯碳酰二肼比色法分析测试了不同状态的304不锈钢样品在自来水环境下的Cr~(6+)溶出规律,并对样品进行了微观组织分析。结果表明,不同状态的不锈钢材料中Cr~(6+)溶出量差别很大,材料中的球状氧化物夹杂尺寸越大、数目越多,对应的Cr~(6+)溶出量越高。采用粉末烧结的方法在金属中引入Cr_2O_3夹杂和Cr_2O_3+MnO_2复合夹杂并测试Cr~(6+)的溶出规律,结果显示MnO_2的添加大幅度提高了Cr~(6+)的溶出量,且氧化物添加量越多,Cr~(6+)溶出量越大。证实了Cr/Mn复合氧化物夹杂分布(尺寸和密度)对不锈钢样品Cr~(6+)溶出量有重要影响:在含Cl的水环境下,Cr/Mn复合氧化物夹杂既是Cr~(3+)来源,又提供了氧化剂使Cr~(3+)转化为Cr~(6+)。这表明通过控制铸件或粉末冶金件中的Cr/Mn复合氧化物夹杂的尺寸和数目,可大幅度降低材料Cr~(6+)的溶出量。
The Cr 6+ dissolution rules of 304 stainless steel samples in tap water were tested by diphenylcarbazide colorimetric method. The microstructure of samples was analyzed. The results show that the amount of Cr 6+ dissolved in different states of stainless steel varies greatly. The larger the size of spherical oxides inclusions, the higher the number of Cr 6+ dissolution. The method of powder sintering was used to investigate the dissolution of Cr 6 O 3 and Cr 2 O 3 inclusions and the Cr 2 O 3 + MnO 2 composite inclusions. The results showed that the addition of MnO 2 significantly increased the amount of Cr 6+, The more the amount of material added, the greater the amount of Cr 6+ dissolution. It was confirmed that Cr / Mn mixed oxide inclusions distribution (size and density) had an important effect on the Cr 6+ dissolution rate of stainless steel samples. The inclusion of Cr / Mn composite oxide was not only Cr 3+ +) Sources, but also provides an oxidant to Cr ~ (3 +) into Cr ~ (6 +). This shows that by controlling the size and number of Cr / Mn composite oxide inclusions in the castings or powder metallurgy parts, the leaching amount of the material Cr 6+ can be drastically reduced.