防氧化脱碳涂料对钢铁材料热处理的保护研究

Study on the protection of the coatings in preventing oxidation and decarbonization of steel and iron materials during heat treatment

分别研究了硅酸盐防氧化脱碳涂料对45#钢和40Cr钢热处理时的保护效果。1 100℃下保温时间对钢样氧化失重率的影响实验表明,随着保温时间的延长,无涂料保护的钢样的氧化失重率迅速增大,但有涂料保护的钢样其氧化失重率变化不大。钢样经1 100℃×2 h热处理后油淬的金相照片显示,45#钢的氧化脱碳程度比40Cr钢更严重,而有涂料保护的钢样其氧化脱碳作用明显减少。经过860℃×4 h与1 100℃×4 h热处理后淬火脱落的涂层其截面SEM形貌显示,涂层的内侧出现较厚的致密层,并呈明显的烧结状态,由能谱分析可知,它应为基体上的氧化膜或氧化膜与涂层成分的反应产物。初步探讨了涂料的防护原理,指出涂层不能避免钢样氧化,而轻微氧化形成的氧化膜能与涂层成分反应形成复杂的氧化物,从而达到较好的防护效果。

The protection effects of silicate coating in preventing oxidation and decarbonization of steel sample of 45# and 40Cr during heat treatment were studied respectively. Experiments on the influences of heat preservation time on oxidation weightloss rate of steel samples show that the oxidation weightloss rate of steel samples without coating increase rapidly and the variation of oxidation weightloss rate of steel samples with coating is not significant. Metallographs of steel sample after 1 100 ℃ × 2 h of heat treatment and oil quenching show that the degree of oxidation and decarbonization of 45# steel sample is worse than that of 40Cr steel while that of the steel sample with coating decrease remarkably. SEM cross-section morphology of falling off coating after 860℃ × 4 h and 1100℃ × 4 h of heat treatment and quenching show that the interior of coating presents thicker and dense layer and obvious agglomeration state. Energy analysis indicates that it might be oxidation film of the substrate and reaction product of oxidation film and components of coating. The protection principle of coating was preliminarily researched. Coating is unlikely to avoid the oxidation of steel sample. Complicated oxides can be formed by the reaction of oxide film due to slight oxidation with the component of coating, resulting in good preventing effect.