Microstructural characteristics and corrosion behavior of HVAF- and HVOF-sprayed Fe-based coatings
Microstructural characteristics and corrosion behavior of HVAF- and HVOF-sprayed Fe-based coatings
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DOI：
10.1016/j.surfcoat.2016.11.088
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发表时间：
2017-05
影响因子：
5.4
通讯作者：
E. Sadeghimeresht;N. Markocsan;P. Nylén
中科院分区：
文献类型：
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作者：
E. Sadeghimeresht;N. Markocsan;P. Nylén
铁基涂层已被证明是更昂贵且不太环保的钴基和镍基涂层的可行替代品。在目前的工作中，对高速空气燃料（HVAF）和高速氧燃料（HVOF）工艺沉积的铁基涂层的微观结构特征和腐蚀行为进行了比较研究。使用不同组的粉末成分和粒度来降低孔隙率并提高涂层的耐腐蚀性。使用电化学技术研究了涂层的腐蚀行为，包括 25 °C 下 3.5 wt% NaCl 中的开路电位 (OCP) 和极化测试。使用扫描电子显微镜 (SEM)、能量色散光谱 (EDS) 和 X 射线衍射 (XRD) 等技术来表征喷涂和腐蚀涂层。结果表明，HVAF 涂层的孔隙率和氧化物含量低于 HVOF 涂层。极化测试证实，采用更细粒度（−36+20μm）喷涂的HVAF涂层比粉末（−53+20μm）喷涂的涂层具有更高的极化电阻（Rp）。根据SEM分析，观察到腐蚀通过涂层的表面缺陷引发和生长，并通过层间边界传播。
Fe-based coatings have been shown to be viable alternatives to the more expensive and less environmentally friendly Co- and Ni-based coatings. In the present work, the microstructural characteristics and corrosion behavior of Fe-based coatings deposited by high-velocity air fuel (HVAF) and high-velocity oxy fuel (HVOF) processes were comparatively investigated. Different sets of powder composition and particle size were used to decrease the porosity and increase the corrosion resistance of the coatings. The corrosion behavior of the coatings was studied using electrochemical techniques, including open-circuit potential (OCP) and polarization tests in 3.5 wt% NaCl at 25 °C. Techniques such as scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffractometry (XRD) were used to characterize the as-sprayed and corroded coatings. The results revealed that the HVAF coatings had lower porosity and oxide content than the HVOF coatings. The polarization tests confirmed that the HVAF coatings sprayed with finer particle size (− 36 + 20 μm) have higher polarization resistance (Rp) than the coatings produced by powders (− 53 + 20 μm). Based on SEM analysis, it was observed that corrosion initiated and grew through the surface defects of the coating and propagated through inter-lamellar boundaries.