The Study of Color Film Phosphating Process in Steel before Coating

摘要

This study through a lot of theoretical analysis and experimental exploration,come to add phytic acid and chromium alum in the traditional zinc phosphating solution for phosphating solution film-forming speed and improve the film density has a distinct effect,and further by orthogonal experiments and the final assessment of preferred a group of environmental,low-temperature,and no sediment of new phosphating process.The composition of the phosphating solution is as follow:zinc oxide 0.5g/L; phosphating acid 5.0mL/L; tartaric acid 0.75g/L; sodium molybdate 0.6g/L; Ma Jif salt 2.0g/L; NaF 0.25g/L; phytic acid 0.4mL/L; chromium alum 1.0g/L; flee acidity 2-4 points; total acidity 15-18 points.The experimental results show that:the new phosphating process of this studyreduces the handling costs,the stability bath performance,little changes in acidity,in the case of do not need to adjust the surface at room temperature,to forming a completed,dense,strong corrosion-resistant color phosphate crystal film on metal surface within 5 minutes,the copper sulfate bit time is 2.5mins,with good adhesion to 0,the impact resistance is 50kg/cm,it can be used in conjunction with a variety of coating processes.