【摘要】 采用纳米压入测试技术,研究了阳极极化对空化作用下奥氏体不锈钢表层力学性能(纳米硬度H_nano和纳米弹性模量E_nano)的影响,并结合失重法与腐蚀形貌分析,探讨了阳极极化对空泡腐蚀过程中协同效应机制的作用.同时,将表层平均纳米硬度与平均纳米弹性模量的比值定义为表层综合力学性能参数（H/E）_nano.结果表明,在不同的阳极极化条件下,空泡腐蚀试样表层纳米硬度、弹性模量和表层综合纳米力学参数的演化规律存在很大差异.随着阳极极化电流增大,表层纳米硬度和表层综合纳米力学参数逐渐减小,表层纳米弹性模量逐渐增大.在空化作用下,当阳极极化处于钝化区时,其协同效应主要为空泡磨损起作用;当阳极极化处于钝化开始向过钝化状态转变时,其协同效应机制为腐蚀引起的磨损过程控制;一旦处于过钝化区,其协同效应则主要为磨损引起的腐蚀过程控制.奥氏体不锈钢表层纳米硬度是决定耐空泡腐蚀性能的关键因素.在空化与电化学腐蚀的交互作用过程中,随着电化学腐蚀增大,腐蚀引起的磨损失重量增大,即非Faraday失重增大,腐蚀表面也因此呈现坑、点、沟槽状的形貌特征.更多还原

【Abstract】 Cavitation corrosion resistances of metals have a very much closed relationship with the mechanical properties of their surface layer.It is very important to investigate effects of surface layer mechanical properties on cavitation corrosion to understand synergistic mechanism.Nano-indentation technology is a sensitively power tool for measuring surface layer mechanical properties in nanometer scale.In this work,it was used to study the effects of anodic polarization on the surface layer nano mechanical properties(nano-hardness,H_nano and nano-elastic modulus,E_nano) of austenitic stainless steel under cavitation.The synergistic mechanism of cavitation corrosion caused by anodic polarization was also investigated by weight loss in conjunction with SEM.The surface layer comprehensive nano-mechanical parameter was defined as（H/E）_nano.It was found that the profiles of H_nano,E_nano and（H/E） _nano with displacement into surface（L） are very different at different anodic polarized potentials.H_nano and（H/E）_nano decrease and E_nano increases with the increment of logarithm of anodic current density.When the samples under cavitation were polarized at passive region,cavitation corrosion of austenitic stainless steel is mainly controlled by erosion.However,it is mainly dominated by corrosion-induced erosion and erosion-induced corrosion,respectively,if anodic polarized potentials were controlled at the beginning of passive to super-passive and super-passive regions.The surface layer nano-hardness is a key factor dominating cavitation corrosion resistances of metals.During the interaction of cavitation with electrochemical corrosion,mass loss of corrosion-induced erosion,which is called non-Faraday weight loss,increases as a result of electrochemical corrosion.The corresponding corroded morphologies with microgrooves,micro-holes and micro-pits were observed.更多还原