Effect of temperature on deposition of LaPO4 coatings produced by ultrasonic-based coating process on steel substrates

High-adhesion LaPO4 coatings were fabricated on steel substrates at temperatures of 150–400 °C after a 10 min treatment using an ultrasonic-based coating process. The principle underlying this process is the collision of ultrasonically accelerated hard balls with the substrate surface that is covered by loosely adhered LaPO4 particles. The repeated substrate-to-ball collisions flatten the precoated LaPO4 particles, bond them together and cold weld them to the substrate. The coating thickness, roughness and structure were found to depend on the substrate temperature. The LaPO4 coatings produced at temperatures ranging from 150 to 250 °C exhibited a granular and porous structure. The treatment at temperatures higher than 300 °C enabled the production of rather dense coatings.