纳米Al_2O_3复合磷化膜分散剂的选择

Selection of Dispersants for Nano-Alumina Doped Composite Phosphating Film

磷化液中加入纳米颗粒Al2O3能提高其综合性能,但纳米颗粒的团聚影响磷化膜性能的提高;磷化液中加入分散剂可以解决纳米颗粒的团聚问题,可以在碳钢表面形成高硬度和高耐磨性的纳米Al2O3复合磷化膜。测试了9种不同分散剂对磷化液沉降值、磷化膜外观的影响,初步优选出3种分散剂:聚乙二醇20000,三乙醇胺,柠檬酸三铵,并配制了复合分散剂。采用SEM观察了优化分散剂对磷化膜微观形貌的影响,用TT260覆层测厚仪测试了膜厚,用电子能谱仪(EDS)分析了复合膜中铝元素的含量。结果表明:复合分散剂和柠檬酸三铵对磷化液中纳米Al2O3的分散效果比较好,阳离子型分散剂三乙醇胺对纳米Al2O3复合磷化膜有细密化的作用。

Nanometer Al_2O_3 doped composite phosphating film was formed on the surface of mild steel by adding Al_2_O3 nanoparticles into the phosphating solution, aiming at increasing the hardness and wear resistance of the phosphating film.Thus various dispersants were introduced into the phosphating solution to get rid of agglomeration of the nanoparticles therein, and three kinds of optimal dispersants, i.e., polyethylene gly-col 20,000, triethanolamine and tri-ammonium citrate, were selected.The effect of the dispersants on the subsidence value of phosphating fluid and appearances of phosphating films were investigated, where the morphologies of the phosphating films were observed using a scanning electron microscope.Moreover, the film thickness was measured using a TT260 thickness tester, and the content of Al in the phosphating film was detected by means of energy dispersive spectrometry (EDS).Results showed that composite dispersant and tri-ammonium citrate were better than the other dispersants in terms of the dispersion capacity for Al_2O_3 nanoparticles, while cationic dispersant triethanolamine was helpful to increasing the compactness of the phosphating films.