(1. 中南大學 粉末冶金國家重點實驗室，長沙 410083；
2. 西安交通大學 電力設備電氣絕緣國家重點實驗室，西安710049)
摘 要: 先采用電沉積-電泳方法在Ni基體高溫合金上制備電鍍Ni/電泳Fe2O3復合涂層，再通過后續(xù)空氣中進行的高溫預氧化處理方法來獲得NiO/NiFe2O4復合氧化物涂層。利用DSC、SEM、EDS和XRD等檢測手段分析預氧化溫度對涂層的結構、微觀形貌、元素分布及相組成等影響，并對涂層形成的反應機理及預氧化動力學進行討論。結果表明：經1 000、1 100和1 200 ℃下氧化4 h后，氧化膜中均生成NiO和NiFe2O4。氧化溫度為1 000 ℃時涂層表面還存在沒有參與反應的Fe2O3，但隨氧化溫度的升高，Fe2O3層隨之消失。溫度為1 100和1 200 ℃時氧化膜中的NiO、NiFe2O4相與鍍Ni基體之間形成了冶金結合，并且通過擴散在NiO相內部形成了NiFe2O4析出相。Ni基體以及電鍍Ni/電泳Fe2O3復合涂層在1 000 ℃預氧化時單位面積上的質量增加隨時間增加，大體遵循拋物線規(guī)律，且電鍍Ni/電泳Fe2O3復合涂層單位面積上的質量增加大于鍍Ni基體的。涂層的厚度與氧化質量增加隨預氧化擴散溫度的提高而增加。
關鍵字: Ni基高溫合金；電沉積；電泳；NiFe2O4；涂層結構；預氧化
（1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. State Key Laboratory of Electric Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China）
Abstract:Electrodeposition-electrophoretic deposition (EPD) technique was employed for fabricating the ferric oxide (Fe2O3) thick films on the Ni-based superalloy, and then pre-oxidation processing method was used to obtain the NiO/NiFe2O4 composite coating. DSC, SEM, EDS and XRD analysis methods were used to analyze the influence of pre-oxidation temperature on the coating structure, morphology, elemental distribution and composition of the phase, and forming reaction mechanism and kinetics of the coating were also discussed. The results show that by high temperature diffusion processes at 1 000, 1 100 and 1 200 ℃ for 4 h, respectively, the oxide film is made up of NiO and NiFe2O4. When the oxidation temperature is 1 000 ℃, there is no reactive Fe2O3 layer on the surface of coating, while with the oxidation temperature increasing, Fe2O3 layer disappears. When the temperature increases to 1 100 and 1 200 ℃, the NiO, NiFe2O4 phase and the Ni plating reach metallurgical combination, and NiFe2O4 spinel precipitates and forms inside NiO matrix phase through diffusion transport. The per unit area mass gain of Ni substrate and electrophoretic Ni/EPD Fe2O3 coating after 1 000 ℃ pre-oxidation diffusion treatment increases with the increase of time, which generally follows the parabolic law, and the per unit area mass gain of Ni/EPD Fe2O3 increases faster than that of the electroplated Ni. The thickness and mass gain of oxide coating obviously increase with the pre-oxidation the increase of temperature.
Key words: Ni-based superalloy; electrodeposition; electrophoresis; NiFe2O4; coating structure; pre-oxidation
