(中南大學 粉末冶金國家重點實驗室，長沙 410083)
摘 要: 通過調(diào)控電沉積過程中的陰極電流密度制備具有不同晶粒尺寸和擇優(yōu)取向的Ni鍍層。采用透射電鏡(TEM)、掃描電鏡(SEM)、能譜儀(EDS)和X射線衍射儀(XRD)對高溫腐蝕前、后不同Ni鍍層進行檢測分析，對比研究不同Ni鍍層經(jīng)過960 ℃的78.07%Na3AlF6-9.5%AlF3-5%CaF2(質(zhì)量分數(shù))熔鹽氣氛腐蝕后的結(jié)構(gòu)、成分和形貌。結(jié)果表明：在高電流密度下易獲得晶粒細小，平均晶粒尺寸為120 nm，具有較強á100ñ擇優(yōu)取向的Ni鍍層；而在低電流密度下所得的Ni鍍層晶粒較粗大，平均晶粒尺寸為925 nm，具有較弱的á111ñ擇優(yōu)取向。在腐蝕氣氛下，低電流密度下所得的Ni鍍層在高溫腐蝕后有利于生成晶粒粗大、且具有完整“八面體”結(jié)構(gòu)的NiAl2O4尖晶石相；而高電流密度下所得Ni鍍層表層腐蝕層的晶粒細小，且主要為NiO相。
關(guān)鍵字: 電沉積；高溫腐蝕性能；鎳；晶粒尺寸；電流密度；擇優(yōu)取向
（State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:Ni coatings with different grain sizes, preferred orientation and impurity element contents can be electrodeposited by regulating cathode current density. Using transmission electron microscopy(TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffractometry(XRD), the oxide film structures, composition and morphology of Ni coatings before and after being corroded in corrosive atmosphere of 78.07%Na3AlF6-9.5%AlF3-5%CaF2 (mass fraction, %) were investigated comparatively at 960 ℃. The results show that Ni coatings with smaller grains and a strong á100ñ preferred orientation are easily obtained under higher current density. While Ni coatings deposited under lower current density have coarser grains and a weak á111ñ preferred orientation. In the corrosive atmosphere, Ni coating prepared with a lower current density is benefit to the formation of dense NiAl2O4 spinel phase on the surface layer, while NiO is the major phase on the surface of oxide film after the corroding Ni coating prepared with a high current density.
Key words: electrodeposition; hot corrosive performance; nickel; grain size; current density; preferred orientation
