Ion-exchange modification of potassium magnesium titanate for high-performance wear–corrosion-resistant composite coatings

Abstract

K2MgTi7O16@K0.8Mg0.4Ti1.6O4(PMTC) core–shell composite whiskers and TiO2 (TO) whiskers have been obtained from potassium magnesium titanate whisker (K0.8Mg0.4Ti1.6O4, KMTO) by a first different degree ion-controlled exchange reaction and a subsequent heat treatment. These materials have been successfully used as functional fillers to enhance the performance of fluorine–olefin vinyl ether copolymer (FEVE) fluorocarbon coatings. The tribological and electrochemical impedance spectroscopy results indicated that PMTC and TO whiskers can significantly enhance the friction and corrosion resistance of FEVE composite coatings compared with KMTO/FEVE composite coatings. Particularly, the 5 wt. % PMTC/FEVE composite coating displays an enhanced wear resistance (Friction coefficient is 0.632. Wear volume loss is 0.006 mm3) than that of pure FEVE coating. (Fiction coefficient is 0.865 and wear volume loss is 0.177 mm3.) And the |Z|0.01 Hz value of 10 wt.% TO/FEVE composite coating is 109.8 Ω·cm2, which indicates its highly protective nature when compared to that of pure coating (~ 107 Ω·cm2). Besides, the microstructure of cross sections, worn surfaces and wear debris of the composite coatings was analyzed by scanning electron microscopy (SEM), and the related anti-wear and anti-corrosion mechanisms were revealed. The present process and design can be extended to the synthesis and modification of a variety of other layered materials including titanates, tantalates, chalcopyrites, etc.