M50钢表面电火花沉积NiCrAlY涂层组织结构及耐蚀性能研究

发布时间：2018-05-06 05:24

本文选题：M50钢 + NiCrAlY涂层　；参考：《哈尔滨理工大学》2017年硕士论文

【摘要】：NiCrAlY涂层由于具有较为优异的抗腐蚀、抗氧化性能,被广泛的应用于海洋环境下的抗腐蚀涂层领域。目前制备NiCrAlY涂层的方法较多,但电火花沉积工艺由于其对基体的形状要求低,可以在形状各异的表面沉积涂层的优点而被广泛采用。因此本研究采用电火花沉积的方式在M50钢表面制备NiCrAlY涂层,探究NiCrAlY涂层的抗盐雾腐蚀性能。采用不同沉积方式、不同沉积厚度及不同沉积参数的方式在M50钢表面沉积NiCrAlY涂层,通过对涂层组织结构、物相组成、结合强度及抗盐雾腐蚀性能等方面的分析,获得了性能较为优异的电火花沉积参数。研究表明:NiCrAlY涂层均匀致密,表面呈泼溅状形貌。随着涂层厚度的增加,涂层表面粗糙度变大,超声焊枪沉积的NiCrAlY涂层均匀致密、无裂纹,但是旋转焊枪沉积的NiCrAlY涂层出现明显的裂纹。沉积电压对涂层形貌裂纹及粗糙度的影响较大,随沉积电压增大,涂层粗糙度变大,旋转焊枪沉积的涂层出现裂纹,而沉积电容对上述形貌的影响较小。NiCrAlY涂层的主要相组成为γ/γ'-Ni/Ni3Al相和m-β相。NiCrAlY涂层与基体为冶金结合,结合强度较高。在抗盐雾腐蚀性能方面,超声焊枪的性能要优于旋转焊枪。且随着涂层厚度的增加,NiCrAlY涂层的抗盐雾腐蚀性能上升。根据轴承的实际应用条件,最优厚度约为40～50 μm。沉积参数的变化对NiCrAlY涂层的抗盐雾腐蚀性能也有影响,随着沉积电压及沉积电容的上升,涂层抗腐蚀性能下降,因此100 V-40μF的沉积参数的涂层抗盐雾腐蚀效果最好。根据沉积速率,形貌及抗盐雾性能等方面的综合考量,NiCrAlY涂层的较优的工艺参数为超声焊枪沉积,沉积电压100V,沉积沉电容40μF,涂层厚度50μm。通过上述最优参数制备NiCrAlY涂层,按照国家标准进行中性盐雾试验,进行M50钢和NiCrAlY涂层的抗盐雾腐蚀机理的研究。M50钢表面在盐雾过程中生成Fe2O3腐蚀产物,随着盐雾试验的进行,Fe2O3含量增加,氧化膜增厚,腐蚀产物产生裂纹及剥落,加速了剥落区域的腐蚀,最终在M50钢表面形成大量腐蚀坑及腐蚀剥落区域。NiCrAlY涂层在盐雾环境下表面也会形成主要成分为Fe、O、Cl、Cr的腐蚀产物,其化学通式为MexOyClz。涂层表面的Fe、Al分别在盐雾过程中形成Fe2O3、Al2O3,最终形成由内至外分别为M50钢、NiCrAlY涂层、Al2O3氧化膜、Fe2O3的四层结构,有效的提高了 M50钢的抗腐蚀能力。
[Abstract]:NiCrAlY coating has been widely used in the field of corrosion resistant coatings in marine environment because of its excellent corrosion resistance and antioxidant properties. There are many methods to prepare NiCrAlY coatings, but EDM deposition technology is widely used because of its low requirements on the shape of various surfaces. Therefore, the NiCrAlY coating on the surface of M50 steel was prepared by electrospark deposition to explore the salt spray corrosion resistance of NiCrAlY coating. The NiCrAlY coating on the surface of M50 steel was deposited on the surface of M50 steel by different deposition methods, different deposition thickness and different deposition parameters. The structure of the coating, the composition of the phase, the bonding strength and the salt fog resistance were used. The results show that the NiCrAlY coating is uniform and dense and the surface is splashed. With the increase of the thickness of the coating, the surface roughness of the coating becomes larger, the NiCrAlY coating deposited by ultrasonic welding gun is uniform and compact, without crack, but the NiCrAlY coating deposited by rotating welding gun is applied. There are obvious cracks in the layer. The deposition voltage has a great influence on the morphology crack and roughness of the coating. With the increase of the deposition voltage, the coating roughness becomes larger and the coating of the rotating welding gun has cracks, while the deposition capacitance has little effect on the above morphology. The main phases of the.NiCrAlY coating are gamma / gamma'-Ni/Ni3Al and m- beta phase.NiCrAlY coating and base. The performance of the ultrasonic welding gun is better than that of the rotating welding gun. With the increase of the thickness of the coating, the corrosion resistance of the NiCrAlY coating increases with the thickness of the coating. According to the actual application conditions of the bearing, the optimum thickness is about 40~50 mu m. deposition parameters to the salt resistance of the NiCrAlY coating. The corrosion resistance of the coating is also affected. With the increase of deposition voltage and deposition capacitance, the corrosion resistance of the coating decreases. Therefore, the corrosion resistance of the coating with the deposition parameters of 100 V-40 mu F is the best. According to the comprehensive consideration of the deposition rate, morphology and salt fog resistance, the better technological parameters of the NiCrAlY coating are the deposition of ultrasonic welding gun. Product voltage 100V, deposition sink capacitance 40 u F, coating thickness of 50 mu m. to prepare NiCrAlY coating through the above optimum parameters, neutral salt spray test according to national standard, study on the mechanism of salt fog corrosion resistance of M50 steel and NiCrAlY coating on the surface of.M50 steel to produce Fe2O3 corrosion product during salt fog process, with the salt fog test carried out, Fe2O3 content increases Adding, the oxide film thickened, the corrosion products produced cracks and exfoliation, accelerated the corrosion of the exfoliation area, finally formed a large number of corrosion pits and corrosion spalling areas on the surface of M50 steel. The.NiCrAlY coating on the surface of salt fog also formed the corrosion products of Fe, O, Cl, Cr. The chemical formula was Fe on the surface of the MexOyClz. coating, Al in salt, respectively. In the process of fog, Fe2O3 and Al2O3 are formed, and the four layer structure of M50 steel, NiCrAlY coating, Al2O3 oxide film and Fe2O3 is formed, which can effectively improve the corrosion resistance of M50 steel.

【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4

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