Improvement in polyurethane coating performance through zinc aluminium phosphate pigment

Abstract

Purpose This research aims to provide a comparative study of the effect of conventional zinc phosphate (ZP) and zinc aluminium phosphate (ZPA) representing second generation of phosphate-based anticorrosion pigments on the protective performance and physical mechanical properties of a solvent-borne polyurethane (PU) coating. Design/methodology/approach The two pigments were incorporated into the coating at optimum pigment volume concentration. To evaluate the protective performance, electrochemical impedance spectroscopy (EIS) was used. The effect of modification of ZP on the physical–mechanical properties of the coatings was studied through dynamic mechanical thermal analysis. Moreover, Micro Vickers hardness and pull-off tests were used to evaluate the hydrolytic coating degradation. Findings EIS revealed the superior protective function of coatings incorporated with ZPA compared to those formulated with ZP. This behaviour might be attributed to the release of sufficient inhibiting species because of partial dissolving of the anticorrosive pigments when an electrolyte penetrates into the coating. In addition, the effectiveness of modification of ZP on the physical–mechanical properties of coatings was shown. Research limitations/implications As a classical replacement for the toxic chromates, ZP has been widely used in the formulation of protective coatings. However, undesirable inhibitive function of the pigment arising from its low solubility has made modification necessary. Because of the modified solubility, second generation of phosphate-based anticorrosion pigments has been reported to reveal superior performance. Originality/value According to the literature, no report can be found studying the effect of the second generation of phosphate-based anticorrosion pigments on the physical–mechanical properties of PU coatings. The main goal of this work is to study the correlation between physical–mechanical properties and anticorrosion performance of the PU coatings.

Aluminium alloy corrosion inhibition by a two-stage modified nanoporous zeolite

“…One of the common methods of protecting metal structures from corrosion is paint coatings, which must have high durability in corrosive environments and at the same time be environmentally friendly [1][2][3]. To ensure corrosion resistance, inhibiting pigments are introduced into the coatings [4][5][6][7]. Several existing inhibiting pigments, such as chromates, show high efficiency but are toxic and cause environmental pollution [8,9].…”

Thin Plasma-Polymerized Coatings as a Primer with Polyurethane Topcoat for Improved Corrosion Resistance

“…Although the corrosion resistance provided by pp coatings is promising, applications require top coats to provide additional functionality such as color and ultraviolet stabilization. , Because of the good adhesion of the pp coating to the metal, we consider the pp coating as a surface treatment to replace the hazardous chromate pretreatment and primer at the same time. For the pp coating as a primer, Boerio et al , tested pp coatings from HMDSO deposited with various carrier gases for their adhesion to Al.…”