A Study on the Effect of Mechanical Activating of Plain Carbon Steel Surface on the Protection Properties of Applied Zinc Phosphate Coating and Paint Adhesion Improvement

Subject Areas : journal of New Materials

L. F.Y ¹ (کارشناس ارشد مهندسی متالورژی و مواد، دانشگاه صنعتی سهند.)
M. آزادبه ² (دانشیار دانشکده مهندسی متالورژی و مواد، دانشگاه صنعتی سهند.)

Received: 2014-02-05 Accepted : 2014-02-05 Published : 2014-05-22

Keywords: Mechanical Activation, Plain Carbon Steel, Zinc Phosphate Coating, Fine Grain Size Structure, Corrosion Resistance, Paint Adhesion,

Abstract :

In this paper, the effect of mechanical surface preparation such as grinding of surface by 180 grade emery papers, sand blasting and shot blasting on the quality of zinc phosphate coating is discussed. The investigation of formed layer by Scanning Electron Microscopy (SEM) technique shown that the very rough shot blasted surface was not created the suitable condition for applying a compact and fine-grained coating. On the other hand, Preparation of surface by sand blasting produced a great number of active centers on the surface and therefore reduced the final size of phosphate crystallites in comparison with grinding operation.Furthermore, the protection properties of samples were described and compared through the neutral salt spray (NSS) test and the electrochemical measuring techniques such as polarization and Electrochemical Impedance Spectroscopy (EIS). The results showed that surface preparation operation by sand blasting before phosphating, has evident influence on improving corrosion resistance. Also, the dry adhesion  investigation of two diverse paint types including air dry paint (Epoxy-Polyurethane) and oven paint (alkyd - melamine paint, (Series YS)) shown that sandblasting of surface, before applying coating, improved the paint adhesion