重型卡车车架磷化工艺

Phosphating process for heavy duty truck frames

重型卡车的车架材质主要由热轧板组成,其表面疏松、多孔,车架表面在脱脂、水洗、表调等工序中极易发黄、生锈。本文对前处理剂进行改进,使之适应热轧板的特性。研究了磷化液中Zn2+、Mn2+及Ni2+质量浓度对磷化膜表面形貌、膜重、P比(即Zn2Fe(PO4)2.4H2O与Zn3(PO4)2.4H2O之比)的影响,得出这几种离子的适宜用量为:Zn2+1.2～1.6g/L,Mn2+0.4～1.0g/L,Ni2+0.7～1.3g/L。所得磷化膜不易生锈,磷化工艺与阴极电泳具有很好的配套性,极大地提升了重型汽车车架的涂装性能。

For its loose and porous structure, the surface of heavy duty truck frames made of hot-rolled steel sheets tends to rust and turn yellow easily during the process of degreasing, washing and surface conditioning. The treatment agent was improved aiming at the characteristics of hot -rolled steel. The effects of the mass concentrations of Zn^2＋, Mn^2＋ and Ni^2＋ in phosphating bath on the surface morphology and weight of phosphating coating and the ratio of Zn2Fe（PO4）2·4H2O （P phase） to Zn3（PO4）2·4H2O （H phase） in it were studied. The suitable concentrations of these ions in phosphating bath are as follows： Zn^2＋ 1.2-1.6 g/L, Mn^2＋ 0.4-1.0 g/L, and Ni^2＋0.7-1.3 g/L. The obtained phosphating coating doesn＇t rust easily. The phosphating process matches the cathodic electrophoresis very well, greatly improving the coating performance for heavy duty truck frames.