Coating density ultrasonic measurement method based on pressure reflection coefficient phase spectrum

Abstract

A coating density ultrasonic measurement method based on sound pressure reflection coefficient phase spectrum, belongs to the field of material ultrasonic non-destructive inspection and assessment technique, which uses a spike pulse ultrasonic waterlogging focusing echo system composed of an ultrasonic flaw analyzer, an ultrasonic spike pulse waterlogging focusing probe, a coating sample, a flume, a digital oscilloscope and a computer. First, the system is used to collect one aliasing signal comprising a coating surface sampling signal reflection signal and a matrix boundary reflection signals, then the system is used to collect a surface echo signal of a standardized block, FFT transformation is respectively performed on the collected sample signal and the standardized signal, data of a real part and an imaginary part are obtained, finally coating density is computed. Ultrasound of 1-20 MHz is used to measure the coating density, also is extendible to measure density of homogeneous coating or heterogeneous coating. The invention is not restricted by the material and uniformity, the device is simple, operation is strong, cost is low, practicality is easy, measurement accuracy is high, repeatability is good.

Description

technical field The invention relates to an ultrasonic measurement method for coating density based on the sound pressure reflection coefficient phase spectrum, which belongs to the technical field of ultrasonic nondestructive testing and evaluation of materials. Background technique So far, there is no practical ultrasonic non-destructive measurement method that can be directly used to measure the coating density. The characteristics of the coating are: the thickness of the coating is relatively thin (micron scale); the coating and the substrate form a multi-interface structure. These two characteristics increase the difficulty of ultrasonically measuring the coating density. At present, the ultrasonic measurement of coating density can be realized by laser excitation of surface waves to measure the phase velocity dispersion curve in the coating, combined with the method of numerical fitting, such as American scholar Krishnaswamy et al. in "Ultrasonic characterization of me...

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Problems solved by technology

At present, the ultrasonic measurement of coating density can be realized by laser excitation of surface waves to measure the phase velocity dispersion curve in the coating, combined with the method of numerical fitting, such as American scholar Krishnaswamy et al. in "Ultrasonic characterization of mechanical properties of Cr-and W -doped diamond-like carbon hard coatings", but the laser ultrasonic system is expensive and limited to laboratory research; in addition, the density can be estimated by measuring the ultrasonic transfer function in the coating combined with parameter estimation methods, such as American scholar Kinra et al. described in the article "Ultrasonic nondestructive evaluation of thin (sub-wavelength) coatings", but this method is only applicable to homogeneous coatings

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