摘要
将HVOF方法制备的NiCrBSi合金涂层在真空炉中加热到600℃保温2 h,采用EIS(电化学阻抗谱)技术研究热处理前后涂层在3.5%NaCl溶液中腐蚀行为随时间的变化情况。结果表明,喷涂过程中滞留在涂层中的气体对涂层的腐蚀行为影响很大。滞留气体可以提高涂层的电极电位和腐蚀抗力,其影响超过涂层组织结构的影响。不过,滞留气体的影响是短期行为,由于气体不断溶解到介质中或以气泡形式进入介质,喷态涂层的腐蚀电位和界面反应电阻在浸泡初期急剧降低,涂层的耐蚀性最终由涂层的组织结构决定。提高涂层的致密性是提高涂层耐蚀性的有效途径。
The NiCrBSi alloy powders were sprayed to a steel substrate using high velocity oxy-fuel(HVOF) after which some coatings were heat treated at 600 ℃ in vacuum for 2 hours,and corrosion behavior of the as-sprayed coating and heat-treated coating in 3.5%NaCl aqueous solution was investigated using electrochemical impedance spectroscopy.The results show that effects of gas trapped in nickel alloy coating on corrosion potential and corrosion resistance of the coating are great.The corrosion potential of as-sprayed coating is higher than that of the gas-removed coating which has been heat-treated in vacuum,because the gas can decrease the electric charge density in electrochemical double layer thus heighten the corrosion potential.The coating can be densified by heat-treatment,but the corrosion resistance of as-sprayed coating is higher than that of the heat-treated coating,so the effects of gas on corrosion resistance are greater than that of microstructure.However,the influence of gas is short-term and the corrosion potential and corrosion resistance decrease dramatically at the early stage of corrosion.The corrosion behavior of coating is determined by microstructure finally.
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2007年第2期99-102,107,共5页
Transactions of The China Welding Institution
关键词
超音速火焰喷涂
金属涂层
腐蚀
气体
热处理
high velocity oxy-fuel spraying
metallic coating
corrosion
gas
heat treatment
