Effects of Aluminide and Platinum-Aluminide Coatings on the Hot Corrosion Behavior of MAR-M247 Nickel-Based Superalloy

本文研究MAR-M247镍基超合金表面经铝化涂层或白金铝化涂层处理后,其热腐蚀效应对腐蚀速率与显微组织之影响,并藉试片质量增加量的变化评估抗热腐蚀的能力.铝化涂层之主要组成为-βN iA l相,而白金铝化涂层表面的主要组成为PtA l2相,利用盐喷覆法将Na2SO4被覆在试片表面,置于热处理炉中观测其热腐蚀性.实验得知,铝化涂层和白金铝化涂层均可明显抑制MAR-M247的热腐蚀,且后者之效果更明显,此两种涂层在910℃之Na2SO4环境中的抗蚀性均较MAR-M247合金为佳.This study is to investigate the high temperature hot corrosion behavior of aluminide coating and platinum-aluminide coating on Ni-base superalloy MAR-M247. On the platinum-aluminide, aluminide and the base metal, respectively, by the salt spraying method. The resistances to hot corrosion of platinum-aluminide coating, aluminide coating and the base metal were evaluated by the variations of weight gains. Aluminide and platinum-aluminide coating showed significanty beneficial effect on inhibiting the hot corrosion of MAR-M247. But that of the platinum-aluminide coating was even much better. The aluminide coating surface was composed of β-NiAl, and that of the platinum-aluminide coating was PtAl_(2). Both two phases could provide better resistances to hot corrosion than that of MAR-M247 in Na_(2)SO_(4), at 910℃.作者联系地址：中山科学研究院飞弹火箭研究所,成功大学材料科学及工程学系,成功大学材料科学及工程学系 台湾台北 ,台湾台南 ,台湾台南Author's Address: *1 ,W.T. Tasi~2,J.T. Lee~21. Missile and Rocket Systems Research Division, Chung-Shan Institute of Science & Technology,Taiwan,China;2. Department of Materials Engineering, Cheng-Kung University,Taiwan,Chin

Effects of Nickel Content and Simulated Heat Affected Zone of 2205 Duplex Stainless Steel on Pitting Corrosion

本文研究了Ｎｉ元素及不同模拟焊后热影响区（ＨＡＺ）组织对２２０５双相不锈钢孔蚀性质之影响．结果发现：在研究成分范围内，不同Ｎｉ含量对于底材电化学极化曲线之影响不大，其Ｅｎｐ和Ｅｎｐ均在１１００～１２００ｍＶ之间．然而不同冷速之Ｇｌｅｅｂｌｅ模拟ＨＡＺ组织，其极化曲线不但阳极电流密度增加，Ｅｎｐ及Ｅｎｐ下降，钝态区域缩小，且循环扫描以后有明显迟滞现象．显示经过不同冷却时间之热履历，已破坏２２０５双相不锈钢抗孔蚀能力，而蚀孔形成后之再钝化能力也变差．电解分离分析法证实形成Ｃｒ２Ｎ之Ｎ含量超过２００×１０－６时，循环极化曲线积分之Ｑ值有显著增加之趋势，显示ＨＡＺ组织抗孔蚀性质能力主要和Ｃｒ２Ｎ析出量多寡有关，Ｃｒ２Ｎ愈多，孔蚀生长之速率也愈快．但部份ＨＡＺ组织会形成Ｃｒ２Ｎ无析出区，此种无析出区不易诱发蚀孔The effects of nickel content and Gleeble simulated heat affected zone(HAZ) of 2205 stainless steel on pitting corrosion were investigated in this paper. The results showed that nickel content, ranging from 4.5 wt% to 6.5 wt% in base metal, had only a minor effect on the electrochemical polarization curves, with all Enp's and Epp's falling in the rang of 1 1001200 mV. Comparing with the base metal, the simulated HAZ microstructure caused an increase in the anodic current density, a distinct decrease in both Enp and Epp , and a reduction in the passive range. Furthermore, hysteresis behavior was found as revealed in each cyclic polarization curve with different cooling cycle. It indicated that the pitting corrosion resistance and repassivation ability of duplex stainless steels were deteriorated by thermal cycling. Electrolytic extraction method proved that the Q values of integral cyclic polarization curves markedly increased while the nitrogen as Cr2N exceeded 20010-6. The susceptibility to pitting corrosion of HAZ was colsely related to the amount Cr2N precipitete. The higher the amount of Cr2N precipitated, the faster the rate of pitting propagation. However, in the nitride precipitate_free zones(PFZ), no pitting corrosion resistance was observed.作者联系地址：成功大学材料科学及工程学系,中国钢铁公司钢铝研究发展处Author's Address: Dept. of Materials Sci. and Engin., Cheng Kung Univ., Tainan Hsieh RongiuanPan Yeongtsuen Steel and Aluminum Research and Development Dept., China Steel Corporation, Kaohsiun