The influence of surface modification of lithium zinc phosphate pigment on corrosion inhibition of mild steel and adhesion strength of epoxy coating

摘要

In this paper, the influence of sol-gel surface modification of lithium zinc phosphate (LZP) pigment by methacryloxy propyl trimethoxy silane on corrosion inhibition, dispersion stability and adhesion strength was studied. IR spectroscopy and fhermogravimetric analysis confirmed that organic functional group was successfully grafted onto the LZP surface. EIS and polarization measurements of mild steel showed an improvement in corrosion resistance for the extract of surface modified pigment in 3.5 % NaCl solution which was connected to better solubility proved by ICP-OES. The dispersion stability of the pigment in epoxy resin was found to be improved after surface modification. In addition, the adhesion strength of the epoxy coating containing surface modified pigment to mild steel after exposure to salt spray (5 % NaCl solution) was enhanced. The sol-gel surface modification had led to increase in hydrophobicity of the pigment particle surface, but simultaneously increased solubility of the pigment in water possibly due to the lower degree of agglomerates or aggregates of the pigment particles.