摘要
实验室小型共渗炉内制备的试样与工业化渗层试样在结构和性能方面不同。为更合理地评价工业化渗层质量,通过工业随炉共渗制备渗锌小尺寸试样,分析了渗锌防腐蚀层的厚度、微观结构、元素分布、硬度,并测试其耐盐雾性能。结果表明:渗锌后工件表面结构可分为Zn-Fe合金层和含Zn过渡层,Zn-Fe合金层在表层,Zn含量较高,是防腐蚀防锈的主要结构层; Zn-Fe合金层与铁基体的界面过渡层厚度约20μm,Zn-Fe合金层与基体结合紧密;渗锌温度高、保温时间长有助于提高工件表面渗层厚度,随炉渗锌小尺寸试样增重法测得的渗层厚度最小,较适用于监控每炉工件共渗质量;合金层硬度高于基体,硬度向基体方向逐步降低,合金层和离界面60μm处的硬度均高于基体30 HV以上,可提高工件表面的耐磕碰性能;常用渗锌温度(420℃)热处理对工件表面硬度无影响,渗锌工件表面硬度增加主要在于表面形成了合金层;随着渗锌层厚度增加,渗层样品耐盐雾性能逐渐提高,渗层厚度宜≥60μm。
To improve the corrosion resistance of metal parts in railway concrete bridge,the small-sized sherardizing coating specimens were prepared by the permeation in industrial furnace and the thickness of the coating was calculated based on the weight increasing method.Besides,the section structure,elements,microhardness and corrosion resistance of the sherardizing coating were analyzed by metallography,scanning electron microscopy(SEM),microhardness tester and neutral salt spray(NSS)test.Results showed that the sherardizing coating included the Zn-Fe alloy layer with the high content of Zn and the interface transition zone between Zn-Fe alloy layer and metal base of about20μm.The Zn-Fe alloy layer was closely combined with the matrix.The layer thickness increased with the increase of temperature and the holding time.The thickness of Zn-Fe alloy layer measured by weight increasing method was the least,which was more suitable for monitoring the sherardizing coating quality of each furnace.The microhardness of Zn-Fe alloy layer was higher than that of metal base.The microhardness of the Zn-Fe alloy layer decreased gradually towards the metal base,and the microhardness of Zn-Fe alloy layer and the position 60μm from the interface were both higher than that of metal base by 30 HV above,improving the bumping resistance of the specimens.The heat treatment at 420℃had no effect on the microhardness of the matrix,and the increase of the hardness of the sherardizing coating specimens was attributed to the formation of alloy layer.With the increase of the thickness of Zn-Fe alloy layer,the NSS corrosion resistance of the sample was improved gradually and the proper thickness of Zn-Fe alloy layer should be more than 60μm.
作者
王涛
WANG Tao(Metals and Chemistry Research Institute,China Academy of Railway Sciences Groups,Beijing 100081,China)
出处
《材料保护》
CAS
CSCD
北大核心
2019年第2期87-90,125,共5页
Materials Protection
基金
中国铁路总公司科研计划(N2018G037
2017G006-1)资助
关键词
金属配件
粉末渗锌
合金层
随炉共渗
防腐蚀
metal parts
sherardizing coating
alloy layer
permeation in industrial furnace
corrosion resistance
