effect of molar ratio and resin modification on the protection properties of zinc-rich alkali silicate primer

the influence of increasing the sio2/k2o molar ratio on the electrochemical action of a waterbornepotassium silicate zinc-rich coating was investigated by means of electrochemical impedancespectroscopy (eis) and corrosion potential (ecorr) measurements. the eis results showed thatincreasing the sio2/k2o molar ratio in the range of 3.135 to 5 by the addition of nano-sio2 to theresins improved the resistance of coatings; however, higher molar ratios showed an adverse effect.moreover, the alkali silicate binder of the sample with a sio2/k2o molar ratio of 5 was improved byadding 5, 10, and 15 wt.% of acrylic resin and acrylic/styrene copolymer to potassium silicate resin.these formulated coatings were sprayed over carbon steel plates and the adhesion and morphology ofthese primers were evaluated by pull-off, cross cut, and scanning electron microscopy tests.electrochemical measurements showed that the sample with a sio2/k2o molar ratio of 5 had bettercorrosion properties than the other samples. adhesion and sem tests also showed that b1 and c2with respectively 5 and 10% acrylic derivatives had less holes, cracks, and better adhesive properties.