NaCl盐膜和水蒸气对纯Cr腐蚀行为的影响

EFFECT OF NaCl DEPOSIT AND WATER VAPOR ON THE CORROSION BEHAVIOR OF PURE Cr at 500-700℃

研究了 50 0～ 70 0℃纯Cr在NaCl盐膜及水蒸气作用下的腐蚀行为。结果表明 ,在单纯空气或O2 +H2 O混合气氛中 ,由于表面生成了一层连续致密的Cr2 O3保护膜 ,即使在较高温度(70 0℃ )下其腐蚀增重也较小 ,表现出良好的抗腐蚀性能。但在NaCl+空气或NaCl+O2 +H2 O协同作用下 ,Cr的腐蚀明显加剧 ,且前者较后者的加速作用显著。在试验温度范围内 ,温度越高 ,Cr的腐蚀越严重。根据实验结果 ,讨论了NaCl加速Cr腐蚀的作用机制。

Thermogravimetric studies have been conducted on the corrosion behavior of pure chromium coated with NaCl deposit in air or oxygen containing water vapor at 500-700℃. Results indicated that in air or in oxygen plus water vapor, the weight gain of Cr sample was not detectable even at 700℃ due to the formation of a compact and uniform Cr_2O_3 protective scale. However, with a solid NaCl deposit on its surface, corrosion of pure Cr in the same environments was significantly accelerated because of the reaction of NaCl with the oxide and substrate metal. When testing temperature increased and approached the melting temperature of NaCl, the corrosion of pure Cr coated with NaCl in air or in oxygen plus water vapor became more severe. A mechanism to explain the syneigistic effect of water vapor and NaCl on the corrosion of pure Cr is proposed.