Surface durability during high-speed spray impingement onto heat-exchanger materials and modified surfaces

Surface durability was investigated for materials used in electronics and heat exchangers during water spray impingement at ambient conditions. Smooth, rough, and modified copper and aluminium samples were tested with surface hardness, roughness and contact angle ranging from 52–100 HV, 0.53–79.28 um and 48-153°, respectively. Although material loss and hardness alterations were insignificant after the high-speed droplet collisions, changes in surface morphology were observed. Both smooth and rough surfaces were resistant to 36-hour sprays with droplet velocities from 11–22 ms−1. However, sprays did cause changes in surface roughness and static contact angle, and the water repellent coatings were damaged, losing their low wettability.