A functional coating with mechanoluminescent properties for sensing cavitation erosion and early warning of protection failure

Protective materials coated on the surface of fluid machinery are often used to slow down the damage caused by cavitation. Once the protective material fails, there is no real-time monitoring to predict, which will directly threaten the safe operation of the equipment. In this work, we designed a functional SrAl2O4: Eu2+, Dy3+ coating by atmospheric plasma spraying (APS), which can sense the impact of bubble implosion and realize the early warning of the failure of anti-cavitation erosion polyurethane (PU) coating. It is found that the luminescent properties of the functional coatings are easily affected by lattice defects, amorphous phase and valence state of europium ions. The functional coating is more sensitive to the perception of micro-jets and shock waves after vacuum thermal reduction treatment, and can distinguish the difference in stress by the brightness of the light. More importantly, when the surface polyurethane coating is removed by cavitation erosion (CE) down to 0.1 mm, this functional coating emits light to warn the polyurethane coating of impending failure. Therefore, this work provided a solution for sensing CE and predicting when the protection would fail。