cleaning, pretreatment & surface preparation
NON-PHOSPHATE TRANSITION METAL
COATINGS
BY BRUCE DUNHAM AND DR. DAVID CHALK, DUBOIS CHEMICALS,
SHARONVILLE, OHIO
INTRODUCTION
Traditional iron phosphate and zinc phosphate conversion coatings havebeen used for more than a century as pretreatments for painting over a varietyof metals. These “legacy” phosphate pretreatments have served well; however,environmental regulations restricting phosphate discharge, increasedphosphate and zinc costs, and higher corrosion-resistance requirements have provided impetus for the development of non-phosphate alternatives. Duringthe evaluations of the various technologies, it was discovered that these newnon-phosphate pretreatment conversion coatings conferred significant costsavings and operational benefits along with their promised decreased environmentalimpact.Considered new and experimental in the New Millennium........
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