Research On Ultrasonic Testing Method And Equipment Development Of Debonding Defect Of Curved Surface Coating

With the gas turbine working environment temperature requirements are getting higher and higher,the requirements of turbine blade heat resistance are getting higher and higher.The turbine blades are separated from the high temperature by spraying a certain thickness of the coating,thereby improving the high temperature performance of the turbine blades.However,due to the coating in the preparation process prone to various types of defects,such as debonding,delamination,uneven thickness.The coating quality of the coating seriously affects the performance and service life of the coating.At the same time,aerial parts are mostly curved surface workpieces,and manual detection efficiency is low,the error is big.As in this paper,the detection object arc surface coating workpiece.Therefore,a set of five-axis characteristic scanning imaging detection system is applied to the ultrasonic imaging of the viscoelastic defects of circular surface coating.The acoustic properties of the Al-Si coating and the matrix were studied,including the speed of sound,the acoustic impedance,the acoustic attenuation and the ultrasonic propagation characteristics.The sound velocity,sound attenuation and acoustic impedance of the Al-Si coating and the alloy matrix were calculated by the pulse reflection method.The difference between the amplitude of the echo and the good position of the bond is calculated by theoretical calculation.According to the characteristics of the arc surface of the thermal barrier coating workpiece,we design five axis ultrasonic feature scan imaging equipment.The system uses servo motor as power core and uses PLC as control center.Developed signal circuit to achieve the control system and the motion power system signal transmission,to ensure stable and orderly motor movement.Designing five axis ultrasonic feature scan imaging software control the system.The software can achieve the motor parameters and movement speed control.According to the test requirements,it set certain accuracy to complete the testing.After the completion of the system,the samples were tested for imaging.The results show that the reflection echo of the coating / substrate bonded surface is higher than that of the bond with good echo amplitude,and the peak value of the two peaks is changed.For the ultrasonic detection of 0.5 ~ 1mm,Ultrasonic focus probe,the use of five-axis flooding ultrasonic imaging system can be stable and efficient completion of the surface coating of the workpiece automatically detected,the use of defective wave imaging can detect the coating and the substrate debonding defects.