Erosion behavior of aluminide coating modified with yttrium addition under different erosion conditions

Oxygen-active elements have recently been found beneficial to the wear resistance of (Cr, Al)-containing alloys in corrosive environments. In this work, the performance of aluminide coating modified with yttrium, a typical oxygen-active element, under different erosion conditions was evaluated. Compared to yttrium-free coating and the mild steel substrate, the yttrium-containing coating showed considerably enhanced erosion resistance under the following erosion conditions: dry sand erosion at different temperatures; erosion in tap water containing 30% silica sand; erosion in a dilute NaCl solution containing 30% silica sand; and erosion in a dilute H2SO4 solution containing 30% silica sand. The study demonstrated that yttrium significantly improved the resistance of aluminide coating to both corrosive erosion and dry sand erosion. Yttrium effects on mechanical properties, micro-wear behavior and corrosion properties were also investigated. It was clarified that the protective role that yttrium played was attributable to its beneficial effect on corrosion behavior rather than the mechanical properties. (C) 2000 Elsevier Science S.A. All rights reserved.