消失模铸造镁合金铸件表面改性研究

Research on Surface Modification of Magnesium Alloy Casting by Evaporative Pattern Casting Technology

利用消失模铸造技术,对镁合金铸件表面进行复合改性研究。选用金属铝粉作为合金化主要元素,PbO-ZnO-Na2O系低温玻璃粉为陶瓷化材料。选择真空度大小为-0.06 MPa,温度为800℃进行浇注。结果表明,在镁合金铸件表面获得了一定厚度的复合层。显微硬度测试表明,从表面至基体复合层的硬度呈梯状分布,硬度值的变化与单一的陶瓷层相比有一个过渡区,有利于提高表面陶瓷层与基体的界面结合质量。经过表面复合改性后,镁合金铸件的腐蚀电位提升了400 mV,腐蚀电流下降了3个数量级,镁合金的耐蚀性得到了大幅度提高。

Lost foam casting technology has been employed in surface modification of Mg-alloy castings.Aluminum powder was chosen as the alloying element,PbO-ZnO-Na2O system low melting point glass powder was used as ceramic material.The vacuum degree of-0.06 MPa,pouring temperature of 800 ℃ were employed.Results showed that a certain thickness composite layer was fabricated on the surface of Mg-alloy casting.The hardness test showed that the micro-hardness of composite layer was in a gradient distribution,in comparison with single ceramic coating,the change tendency had a transition region from the surface ceramic coating to the substrate,which was beneficial to raise the bonding interface quality between the surface ceramic coating and substrate.After surface composite modification,the corrosion potential was raised 400mv,corrosion current declines three orders of magnitude,corrosion resistance of mg-alloy was enhance greatly.