新型渣浆泵用材料的腐蚀性能研究

Study on Corrosion Properties of New Material for Slurry Pump

针对渣浆泵用耐磨蚀材料在服役过程中由于腐蚀严重导致使用寿命缩短的问题,研发了一种新型耐磨蚀材料(A合金)。采用金相显微镜、X射线衍射仪、全浸腐蚀、扫描电镜、极化曲线、阻抗谱、X射线光电子能谱对材料在模拟服役环境腐蚀液中的腐蚀速率、腐蚀特征、电化学特性以及钝化膜组成进行了分析。将A合金与SUS316L不锈钢、KMTBCr26高铬铸铁进行对比分析,结果表明:A合金的显微组织是由高铬的奥氏体基体以及高硬度的M23C6型碳化物组成,这种碳化物类型使得材料具有优异的耐腐蚀性能。在室温条件下腐蚀192h,A合金、SUS316L、KMTBCr26的腐蚀速率分别为0.0197mm/y、0.322mm/y、26.0396mm/y。A合金表面出现少量点蚀坑,而SUS316L和KMTBCr26材料表面发生局部腐蚀甚至全面腐蚀。A合金基体在析出碳化物后Cr含量没有出现贫化,降低了相与基体之间的腐蚀电位差;材料中富含的Cu元素使得表面钝化膜的稳定性提高。在电化学腐蚀过程中,A合金的自腐蚀电位最高、腐蚀电流密度最小、阻抗谱容抗弧半径最大、腐蚀倾向最小、表面形成的钝化膜稳定性最强,钝化膜的组成为Fe2O3、Cr2O3以及部分Cu氧化物。

A new type of wear-resistant material (A alloy) was developed for the problem that the wear-resistant material of the slurry pump was reduced in service life due to severe corrosion during service. The corrosion rate,corrosion characteristics,electrochemical characteristics and passivation film composition of the materials in the mixed acid solution in the simulated service environment were examined by metallographic microscope,X-ray diffractometer,total immersion corrosion,scanning electron microscopy,polarization curve,impedance spectroscopy,X-ray photoelectron spectroscopy,compared with SUS316L stainless steel and KMTBCr26 high chromium cast iron. The results showed that A alloy microstructure consists of a high chromium austenite matrix and a high hardness M 23 C 6 carbide. This type of carbide gives the material excellent corrosion resistance. Corrosion at room temperature for 192 h,the corrosion rates of A alloy,SUS316L and KMTBCr26 were 0.019 7 mm/y,0.322 mm/y and 26.039 6 mm/y,respectively. A small amount of pitting pits appeared on the surface of A alloy,while local corrosion or even overall corrosion occurred on the surface of SUS316L and KMTBCr26. There is no depletion of Cr content in the A alloy matrix after precipitation of carbides,which reduces the corrosion potential difference between the phase and the matrix. The Cu element rich in the material improve the stability of the surface passivation film. In the electrochemical corrosion process,A alloy has the highest self-corrosion potential,the lowest corrosion current density,the largest impedance radius and the lowest corrosion tendency,and the strongest surface passivation film. The composition is Fe 2O 3,Cr 2O 3 and some Cu oxide.