Research And Development Of A New Type Of Ultrasonic Testing Coupling Medium

The ultrasonic testing has the very important position in the field of nondestructive testing and medical science.In the process of automatic detection,coupling medium provide the necessary link between ultrasonic sensors and checked materials.At present,nondestructive testing of industrial pipe often use water as a coupling agent all at once,which is convenient to be cleaned and low cost at the same time.But when testing,the water losses seriously.This causes great waste of resources.When detect insulation pipe,it is hard to clean water treatment in thermal insulation layer,which bring huge trouble to testing work.This topic is proposed under the background of such applications.The purpose of this experiment is to develop a kind of solid coupling medium,whose sound impedance and acoustic attenuation coefficient is close to the water and it has a certain water seepage properties and strength.At the same time the acoustic impedance of coupling medium can be adjusted according to the test object,which can make the ultrasonic wave transmit through the interface.This is a resource conservation,environmental testing,also has a better protect to the insulation pipeline,realizing the goal of the experiment.In this experiment,select a variety of polymer materials and mix them with water in different proportion.Through dissolving,heating and cooling process,it can form a solid coupling gel.Use ultrasonic testing instrument to measure the sound velocity and attenuation coefficient of the coupling medium.And compare it with water.Do experiments with different frequency probes to verify the influence of probe frequency to acoustic characteristics of the coupling mediums.At the same time measure its water loss rate and service life by monitoring the change of the coupling medium acoustic characteristics.Finally,use the standard block to test the application performance in practice.The experiment results show that carrageenan and agar are very ideal,whose sound velocity and attenuation coefficient are quite close to water,and have a certain strength and water retention performance.Sound velocity increases and acoustic attenuation coefficient decreases with the increase of the coupling medium concentration.Probe frequency almost has no effect on acoustic characteristics.Water loss rate increases with time.The two coupling mediums are time-efficient.When using the standard test block,the sound pressure reflection coefficient of the coupling medium is close to that of water and there is no interfaceecho when mixed with water.The two coupling mediums can satisfy the requirements of the measurement.