摘要
为解决低碳铝镇静钢汽车板在磷化工艺下限条件下磷化膜结晶粗大及覆盖率不足问题,采用扫描电镜(SEM)、表面轮廓仪、辉光光谱仪(GDS)及透射电镜(TEM)研究了低碳铝镇静钢汽车板磷化性能关键影响因素,并提出了改善对策。结果表明:当磷化工艺处于下限条件即促进剂浓度、总酸浓度较小,而游离酸浓度较大时,钢板与磷化液界面磷酸盐不易饱和,磷化形核难度加大,导致磷化结晶粗大及覆盖率不足等问题。但当钢板表面存在均匀分布且数量较多的小尺寸氧化物颗粒时,氧化物与铁基体能够形成大量原电池,提升局部磷化酸蚀及沉积反应速度,进而改善磷化性能。通过对低碳铝镇静钢碳含量及退火快冷段、过时效段温度进行控制,成功在钢板表面析出尺寸较小且均分分布的碳化物。由于碳化物与铁基体之间存在电位差,同样增加了钢板表面原电池数量,促进了磷化形核,所获得的磷化膜晶粒尺寸在5μm以下,覆盖率为100%。
In order to solve the problem of coarse crystallization and insufficient coverage of the phosphating film on low-carbon aluminum killed steel automotive panels under the lower limit conditions of the phosphating process,the key influencing factors on the phosphating performance of low-carbon aluminum killed steel automotive panels were studied using scanning electron microscopy(SEM),surface profiler,glow spectrometer(GDS),and transmission electron microscopy(TEM),and improvement strategies were also proposed.The results show that when the phosphating process is at the lower limit,namely the concentration of accelerator and total acid is low,while the concentration of free acid is high,the phosphate at the interface between the steel plate and the phosphating solution is not easily saturated,and the difficulty of phosphating nucleation increases,leading to problems such as coarse phosphating crystallization and insufficient coverage.However,when there are a large number of small oxide particles evenly distributed on the surface of the steel plate,the oxide and the iron matrix can form a large number of primary batteries,which can improve the local phosphating acid etching and deposition reaction speed,and thus improve the phosphating performance.By controlling the carbon content of low carbon aluminum killed steel and the temperature of annealing rapid cooling section and over aging section,carbides with small size and evenly distributed are successfully precipitated on the steel plate surface.Due to the potential difference between carbide and iron matrix,the number of primary batteries on the steel plate surface is also increased,which promotes the nucleation of phosphating.The grain size of the obtained phosphating film is under 5μm,the coverage rate is 100%.
作者
张亮
郝玉林
刘兴全
林兴明
孙鹏
王志涛
Zhang Liang;Hao Yulin;Liu Xingquan;Lin Xingming;Sun Peng;Wang Zhitao(Beijing Shougang Co.,Ltd.,Beijing 100041,China;Research Institute of Technology of Shougang Group Co.,Ltd.,Beijing 100043,China;Tianjin Shougang Iron&Steel Trading Co.,Ltd.,Tianjin 300000,China)
出处
《电镀与精饰》
CAS
北大核心
2024年第2期22-29,共8页
Plating & Finishing
关键词
低碳铝镇静钢
磷化
氧化物
碳化物
low carbon aluminum killed steel
phosphating
oxide
carbide
