搪瓷表面凹坑缺陷的形成原因分析

Analysis of causes for the formation of pit defects on the surface of enamel layer

冷轧搪瓷用钢生产烤箱内腔经静电喷涂和烧结后表面会出现凹坑缺陷,采用金相显微镜、扫描电镜和EDS能谱仪等分析手段,对缺陷纵切面的显微形貌特征进行观察,确定其形成原因。详细阐述了缺陷附近及缺陷处搪瓷钢板界面、搪瓷层的显微形貌和元素分布特征,结果表明,凹坑缺陷是由钢板表面的点锈所致,在高温搪烧过程中,点锈中铁的氧化物和瓷釉熔体未发生充分的熔合和反应而导致的,点锈的出现与用户的搪前处理工艺密切相关。为了避免发生缺陷,要在钢板成形、脱脂和彻底烘干后,及时进行静电喷涂和烧结。

During the production process of the inner walls of ovens,pit defects were formed on the surface of enamel layer after cold rolled steel for enameling was electrostatic powder sprayed and sintered.Optical microscopy,scanning electron microscopy,and energy dispersive spectroscopy were adopted to investigate the microstructure of the longitudinal section of the defect,and then the forming cause was analyzed.The paper elaborates the microstructure and element distribution of the enameled steel interface and the enamel layer.The results shows that rusty spot leads to the pit defects.During the process of high-temperature firing,there is an inadequate fusion and reaction between iron oxides of the rusty spot and enamel glaze.Rusty spots are closely related to pretreatment process;thus,to avoid the occurrence of rusty spots,electrostatic powder spraying and sintering should be timely carried out after forming,degreasing,and thoroughly drying.