Cavitation Erosion Behavior Of Titanium Alloy Films Prepared By Ion Beam Enhanced Deposition

The metal coatings have been widely used in microelectromechanical systems with the rapid development of microelectromechanical. When the liquid is flowing through the micropumps and microvalves, there is definitely a possibility of cavitation erosion in the micro-electromechanical systems if apt hydrodynamic conditions develop, just like the cavitation erosion in the conventional scale hydraulic machinery. The cavitation erosion performance of coatings prepared by ion beam enhanced deposition were investigated on a ultrasonic magnetostrictive cavitation erosion tester. The cavitation erosion process and mechanism were analyzed, and the influence of the different power of the tester on the cavitation erosion performance was explored. The main conclusions are as follow:1. A lot of cavitation pits were produced on the surface of the titanium alloy films after the cavitation test, and the positions and sizes of the pits were stochastic. The number and size of the pits increased with the testing time. It was found that the pits were caused by the effect of cavitation bubbles collapsed. The size and position were decided by the distribution of cavitation bubbles on the surface of the tester.2. It was found that there existed different cavitation erosion behaviors by contrasting the cavitation erosion process of titanium alloy films and the titanium alloy bulk. There are no obvious slippage and deformation along the grain boundary both on the surface of the titanium alloy films and the titanium alloy bulk. There is obvious plastic deformation during the cavitation erosion process of the the titanium alloy bulk, but it is not found during the cavitation erosion process of the the titanium alloy films.3. The cavitation erosion progressed into incubation period, concave formation by the effect of cavitation bubbles collapsed, delamination, and localized fracture, corresponding to the four stages of the cavitation erosion.4. The optical microscope topographs of the samples during the stages of cavitation erosion were treated with the colors-abstraction method. The Cavitation erosion curves were drawen according the data of the colors-abstraction process. It is found that two-color image processing can exhibit the inception of cavitation erosion process well, which can be used to analyze surface changes of the materials qualitatively.5. After the cavitation erosion test with different powers, it was found that the damaged area of samples increased with the power in the same testing time, and it was easy to get the stage of coating's desquamation. Because the cavitation intensity was altered with the change of the ultrasonic intensity of the device, and the ultrasonic intensity was decided by the power of the device.