借助稀土优良的物化特性改善低温熔融渗硫层的抗蚀性。考察了稀土添加剂的类别和加入量对渗层腐蚀行为的影响规律，基于孔蚀理论揭示了微量稀土的作用机理，确定了稀土添加剂的优选方案。研究表明：采用稀土催渗的渗硫试样抗大气和电解液腐蚀性能均明显改善，其在5 wt % NaCl溶液中的稳定电位升高，失重率仅为非稀土催渗试样的1/2左右；改善效果取决于稀土元素及其阴离子种类，其中CeCl3效果最佳，其次为LaF3、La2O3、LaCl3和YF3；综合稀土的催渗效果以及渗层耐蚀性要求，宜采用适量的LaF3（催渗效果最好）与CeCl3共同配制渗硫剂，合适的添加比约为4：1。
Low temperature melted sulfurization,catalyzed by rare earth elements,on quenched Cr12 steel surface was investigated.Morphologies and chemical compositions of the sulfide coatings were analyzed by SEM and AES,respectively.Meanwhile,atmospheric exposure test and electrolyte soaking method were applied to investigate the effect of different rare earth catalyzers and their content on corrosion resistance of sulfurized Cr12 steel.The results showed that corrosion resistance of sulfide layers in air and brine could be improved evidently due to the addition of rare earth elements in the sulfide coatings. The steady potential of sulfide coatings obviously increased and its mass-loss-rate decreased by 38%~ 50% in 5% NaCl solution.The improving extent of corrosion resistance relates with the kind and content of rare earth element.The advantage of CeCl3 was by far better than that of LaF3, CeF3 and LaCl3. Considering the excellent catalysis of LaF3, it is better to use LaF3 and CeCl3 mixture in the sulfurizing reagent,which optimized ingredient was S + 4.0 mass% LaF3 +1.0 mass% CeCl3 for the low temperature melted sulfurization of Cr12 steel.
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