激光选区熔化AlSi10Mg表面微弧氧化及其耐磨耐蚀性

Wear and Corrosion Resistance of AlSi10Mg by Selective Laser Melting and Micro-arc Oxidation

为了提高轻质合金3D打印的耐磨、耐蚀性能,对激光选区熔化(SLM)铝合金(EOS:AlSi10Mg)打印成形后进行表面微弧氧化。采用应力分析仪、扫描电子显微镜、高温摩擦磨损、中性盐雾试验箱等设备,进行了残余应力测试,微观组织分析,摩擦磨损和腐蚀性能试验。结果表明,3D打印铝合金试样直接进行微弧氧化,由于残余应力(200MPa左右)较大,微弧氧化时表面氧化反应过程中促进了应力释放,使微弧氧化层加剧产生粗大裂纹;对打印后试样进行去应力热处理后,微弧氧化后表面仅见少量微小的工艺扩展裂纹。去应力后的微弧氧化层表面,平均摩擦因数由0.545降低到0.441,腐蚀环境后的抗腐蚀等级由9级提高到10级,证明3D打印激光立体成形热应力对成形零件的微弧氧化工艺性能影响较大。

Micro-arc oxidation process was applied to 3D printed parts （material： EOS AlSi10Mg） after selective laser melting （SLM） to improve its wear resistance and corrosion resistance. The residual stress, microstructure, frictional wear performance and corrosion properties were characterized by X-ray diffraction stress analyzer, SEM, high temperature friction and wear tester, and neutral salt spray tester, respectively. Results show that for the as-built 3D printed specimens, large tensile residual stress （about 200 MPa） is measured on the surface. Meanwhile, the subsequent micro-arc oxidation process promotes the stress release, and thus, numerous micro cracks are observed in the micro arc oxidation layer of the as-built specimens. The surface cracking in the micro-arc oxidation layer is found to be decreased when the as-built specimens are annealed before micro arc oxidation process. Additionally, for the annealed 3D printed specimens after micro arc oxidation treatment, the average frictional coefficient decreased from 0.545 to 0.441 and the anti-corrosion rating increased from 9 to 10. Clearly, the thermal stress in SLM 3D printing process significantly influences the effectiveness of the micro-arc oxidation process.