CAJ | 학술논문

以磷酸盐化学转化膜为研究体系,采用SEM、XRD、OCP等分析方法及检测手段,研究AZ91D镁合金系磷酸盐化学转化膜的成膜机理、膜层结构及生长过程.研究发现AZ91D镁合金在磷化液中成膜过程分5个阶段:初始成核(1～5s)、基体快速溶解(5～60s)、晶体快速生长(1～2min)、膜层稳态生长(2～10min)和膜层沉积溶解平衡阶段(10min以后).AZ91D镁合金表面的磷酸盐晶核的形成并非在金属进入溶液的最初时刻一次形成,是分批形成.最先形成的晶核逐渐长大,新的晶核不断生成,磷酸盐晶粒对其表面的覆盖度逐渐增大,直至各个晶粒逐渐长大相互接界,将其表面完全覆盖,结晶过程结束.晶核的形成未优先发生在基体金属的晶界上,随着晶核的生长和外延而形成磷化膜.
이린산염화학전화막위연구체계,채용SEM、XRD、OCP등분석방법급검측수단,연구AZ91D미합금계린산염화학전화막적성막궤리、막층결구급생장과정.연구발현AZ91D미합금재린화액중성막과정분5개계단:초시성핵(1～5s)、기체쾌속용해(5～60s)、정체쾌속생장(1～2min)、막층은태생장(2～10min)화막층침적용해평형계단(10min이후).AZ91D미합금표면적린산염정핵적형성병비재금속진입용액적최초시각일차형성,시분비형성.최선형성적정핵축점장대,신적정핵불단생성,린산염정립대기표면적복개도축점증대,직지각개정립축점장대상호접계,장기표면완전복개,결정과정결속.정핵적형성미우선발생재기체금속적정계상,수착정핵적생장화외연이형성린화막.
The formation mechanism,coating structure and growing process of zinc phosphate coating on AZ91D magnesium alloy were studied by means of scanning electron microscopy(SEM),X-ray diffraction(XRD),open circuit potential(OCP) .The results show that the growing process of zinc phosphate coating on AZ91D magnesium alloy forming in the phosphating bath process is divided into five stages: the initial nucleation stage(1-5s),the rapid dissolution stage(5-60s),the rapid growth stage(1-2min),steady-state growth stage(2-10min) and the deposition-dissolution equilibrium stage(after 10min).The hopeite phosphate coating on AZ91D magnesium alloy formed in the zinc phosphating bath by batches.The first batch of hopeite nucleus grow into grain gradually,continuous nucleation of new generation occurred simultaneity.The coverage of phosphate grain increased gradually on the alloy surface,the boundary of grain growing closed,and the phosphating process is end until the entire surface is completely covered.With the growth of nucleation and its epitaxial,the phosphate coating formed of on AZ91D magnesium alloy,which is not occured in the metal matrix of the grain boundary with priority.