Electrochemical aspects of protection afforded by finish coat on zinc‐rich primers

Abstract

A barrier type of finish coat on zinc‐rich primers can effectively prevent corrosion on mild steel structures in marine environments. Chlorinated rubber is well known for its impermeability of water vapours and corrosive ions. Micaceous iron oxide (MIO) and titanium dioxide (Ti02) are the best barrier pigments available in the world. The chlorinated rubber based top coatings have been prepared by incorporating these two pigments separately and applied over three types of zinc‐rich primers (ZRP) (butyl titanate ZRP, cashew nut shell liquid ZRP and epoxy polyamide ZRP). The electro chemical aspects of protection afforded by these coating systems have been evaluated on mild steel substrate in 3 percent NaCI solution by potential‐time, polarisation and impedance techniques. This study revealed an interesting correlation between the polarisation and impedance observations. The inorganic ZRP with top coated systems behave differently to organic ZRP with top coated systems. The MIO pigmented finish coat affords equally higher duration of protection of steel substrate from corrosive saline environment, even though the PVC value is considerably lower than the TiO2 pigmented top coat systems.

Corrosion Inhibitors: Other Important Applications

“…Coating with this is comparable to red lead in linseed oil in protection. Protection of passenger car bottoms by using priming coats with the pigment achieved [74] Barium oxide-iron oxide Developed for corrosion control of fertilizer plants. Corrosion protection is satisfactory [75] Zinc phosphate/barium phosphate primer Nontoxic and promotes excellent intercoat adhesion.…”

Eco‐friendly, acrylic resin‐modified potassium silicate as water‐based vehicle for anticorrosive zinc‐rich primers

“…Spectra depression is due to the porous nature of the coatings. 7,22 The EIS data were fitted using Zview and Zsim softwares. Table III shows the EIS extracted parameters for B series (modified with acrylic/styrene).…”

“…The impedance reduction for first few days is due to zinc particles activation, and then it increases because of reduction the active surface area due to zinc consumption and zinc corrosion products formation in the pores of the coatings. Spectra depression is due to the porous nature of the coatings . The EIS data were fitted using Zview and Zsim softwares.…”

A novel approach to the synthesis of a non‐toxic, platy pigment for anticorrosive paints

“…Pigments obtained from these deposits vary considerably in morphology, physical characteristics and chemical purity. MIO is a metallic grey lamellar form of Fe 2 O 3 ; its flake‐like particle structure is responsible for the barrier effect (Carter, 1988; Bishop and Zobel, 1983; Kalendova, 2002a; Kalendova and Snuparek, 2000; Selvaraj and Guruviah, 2001; Giudice and Benitez, 2000).…”