Development of New Cavitation Resistant Coatings

Abstract Damage caused by cavitation is observed on hydro-turbines, pumps, pipes, gates, draft tubes, and outlet conduits. Mitigating the effect of cavitation on structures will reduce cost in repairs and downtime. Traditionally, stainless steel weld overlays are used for cavitation repairs on metallic structures. Welding stainless steel to mild steel creates a galvanic corrosion cell, which causes the steel to corrode and delaminate the stainless steel, resulting in no cavitation protection. Cavitation resistant coatings could be used in combination with stainless steel weld overlays to reduce the galvanic corrosion cell, thus providing dual protection and extending the service life of the repairs. Unfortunately, most coatings cannot withstand moderate or severe cavitation, but only work under mild cavitation such as in draft tubes. This research developed new cavitation resistant polyurethane elastomers with over 100 times better than most commercially available cavitation resistant coatings, possibly can perform in moderate and severe cavitation environments. Field trials have begun on a small turbine runner.