This study investigates the synergistic effects of cavitation and corrosion on Cr 3 C 2 -25NiCr coatings with different levels of porosity. The coatings are deposited by HVOF spraying and evaluated based on SEM analysis, Vickers microhardness, potentiodynamic polarization measurements, and cavitation erosion tests in various environments under ultrasonic vibration. The results show that higher porosity reduces both cavitation and corrosion resistance, as expected. However, the samples did not show significant alteration of their cavitation properties in NaCl, probably because of the high corrosion resistance of the different phases in the coating. The influence of HVOF fuel-oxygen ratio and total gas flow on coating porosity, as well as phase morphology, is also discussed.

This paper discusses some of the practical uses of laser cladding and laser fusing in part manufacturing and component repair. It provides an overview of both processes and the types of surfaces they can produce. It presents application examples for each process and interprets corrosion and wear properties of the respective coatings. It also discusses the benefits of repair friendly surfaces.

Problems with corrosion resistance in hydraulic cylinders used in marine environments contribute to many failures. Thermal spraying has proven to be a reliable method for replacing electroplated coatings in aircraft, but performance in high corrosive environments is still a drawback. In the present work, a new sealing method to densify WC-CoCr HVOF coatings is tested, which appears to be applicable to hydraulic cylinders in marine environments. The method is based on the use of nanoparticle solutions that penetrate and fill pores and cracks to seal the coatings. Two such solutions are tested and compared to as-sprayed coatings. Open-circuit potential and tribocorrosion measurements in 3.4% NaCl show that sealed coatings are more resistant to corrosion and wear than as-sprayed layers.