基于正交试验的磁控溅射铝涂层对孪晶诱发塑性钢耐蚀性的影响

Corrosion Resistance of Magnetron Sputtering Aluminum Coating to Twinning-induced Plasticity Steels Based on Orthogonal Test

目的利用磁控溅射技术在孪晶诱发塑性钢板表面沉积铝涂层,借助L9(3^(3))正交试验设计表研究热丝电流、靶电流和基体偏压3个工艺参数对铝涂层相结构、微观形貌以及耐蚀性能的影响。方法利用XRD和SEM研究铝涂层的微观结构。利用电化学工作站和盐雾试验箱测试并分析铝涂层的耐蚀性能。通过极差分析得到热丝电流、靶电流和基体偏压所对应的极差值(R值)。结果引入热丝后,基体偏流密度从0.02 mA/cm^(2)提升至0.72 mA/cm^(2),提高了1个数量级;靶电流与基体偏压的影响不明显。涂层厚度随靶电流的增加而增大,靶电流由3 A增至9 A的过程中,涂层厚度由0.67μm增加至3.16μm。择优取向在热丝电流与基体偏压的共同作用下由(200)向(111)转变,这反映了晶体内部应力增大。铝涂层均为典型的再结晶形貌。在热丝电流从0 A增大到20 A的过程中,自腐蚀电位由-969 V增大至-656 V,靶电流和基体偏压的影响较小。自腐蚀电流密度随靶电流的增加而增大,当靶电流从3A增至9A时,其数值由1.15×10^(-7)A/cm^(2)增大为3.04×10^(-7)A/cm^(2);自腐蚀电流密度随热丝电流和靶电流呈现先增后减的趋势。腐蚀面积与热丝电流成正相关,热丝电流越大,腐蚀面积越大(5.03%~12.21%);腐蚀面积与靶电流成负相关,靶电流越大,腐蚀面积越小(10.62%~6.51%)。结论热丝电流主要影响涂层的致密度,热丝电流越大,涂层越致密,自腐蚀电位越高。靶电流主要影响涂层厚度,涂层越厚越耐蚀,同时也变得疏松,点蚀增多。基体偏压对于铝涂层的耐蚀性影响不大。

Magnetron sputtering technique has considerable application prospects in the surface anti-corrosion aspect of automobile steel,especially Twinning Induced Plasticity(TWIP)steel.Aluminum(Al)coating is a preferred coating for TWIP steel,however,the effect of various process parameters on the corrosion resistance of Al-coated TWIP steel was not clear.In this work,hot wire plasma enhanced magnetron sputtering(PEMS)technology was used to deposit Al coatings on the surface of TWIP plate guided by the L9(33)orthogonal test design table.The three factors were hot wire current(Ih),target current(It)and substrate bias voltage(Vs),and each factor corresponded to three levels.The effects of above three factors on the corrosion resistance of Al coatings were analyzed by means of range analysis and variance analysis.The phase structure and micromorphology of Al coatings were investigated by an X-ray diffractometer(XRD)and a scanning electron microscope(SEM)respectively.The corrosion resistance of aluminum coating was tested and analyzed by an electrochemical workstation and a salt spray test chamber.The range value(R value)corresponding to Ih,It and Vs was obtained by range analysis,meanwhile,some results were also analyzed by variance analysis.The bias current density of substrate increased from 0.02 mA/cm^(2) to 0.72 mA/cm^(2) after adding Ih.But the influence of It and Vs was not obvious.The thickness of Al coatings increased from 0.67μm to 3.16μm with the increase of It(3 A to 9 A),however,the effects of Ih and Vs were not significant.The preferred orientation of Al coatings changed from(200)to(111)under the combined action of Ih and Vs which reflected the increase of internal stress.The SEM results showed the typical recrystallized morphologies of Al coatings.The self-corrosion potential increased from‒969 V to‒656 V with the increase of Ih,and the influence of It and Vs was small.The self-corrosion current density increased first and then decreased with Ih and It.The corrosion area was positively correlated with Ih(5.03%to 12.21%).while It acted just oppositely(10.62%to 6.51%).Therefore,hot wire current was the most significant measure of self-corrosion potential and percentage of corrosion area.The results showed the density of Al coatings was mainly affected by Ih.With Ih increased,the coatings became denser and self-corrosion potential get upper.Target current mainly affected the thickness of Al coatings.When the coating was thicker,the corrosion-resistant was better,but the coating became looser and corrosion pits increased.The substrate bias voltage had little effect on the corrosion resistance of Al coatings.In summary,the introduction of hot wire power supply has both advantages and disadvantages on the corrosion resistance of Al-coated TWIP steel sheets.As for the selection of specific process parameters in actual production,it needs to be determined by considering the target service life and specific service condition of the TWIP automobile sheet.