Method for detecting piezoelectric material surface layer Young modulus through laser acoustic surface waves

Abstract

The invention discloses a method for detecting piezoelectric material surface layer Young modulus based on a laser acoustic surface wave technology. The method comprises the steps of utilizing a pulse laser for exciting high frequency acoustic surface waves on the surface layer of a piezoelectric test piece, picking up acoustic surface wave signals with the propagation distance ranging from 1 cm to 2 cm for processing, fitting dispersion curves, and obtaining the phase velocity approaching a true value; establishing a laminated piezoelectric material model under an ideal condition, uniting a wave equation and an electromagnetic wave equation of the acoustic surface waves on piezoelectric media, and obtaining a basic propagation equation of the surface waves; calculating the corresponding relation between the wave velocity and the wave number in combination with boundary conditions of the piezoelectric media; obtaining the relation among the wave velocity, the frequency and the Young modulus under the ideal condition, conducting analysis and comparison on the dispersion curves fitted through tests, and obtaining the absolute Young modules E<->, the minimum Young modulus E and the maximum Young modules E of the tested piece. By means of the method, the reliability and anti-interference property of a detection result can be improved, a detection device is transformed toward miniaturization, confidentiality and the like, and application of the technology to theoretical research and practical application is promoted.

Description

technical field [0001] The invention belongs to the field of material performance detection and specifically designs a method for detecting the Young's modulus of the surface layer of a piezoelectric material. Background technique [0002] Piezoelectric materials are materials that can convert electrical energy into mechanical energy. When an external force acts on the piezoelectric material and causes the material to deform, a discharge phenomenon occurs. Piezoelectric materials are widely used in thermo-optoacoustic electronics and other fields because of their unique properties, simple fabrication, low cost, and high energy conversion efficiency. With the development of high technology in this field, people have higher and higher requirements on the performance of piezoelectric materials. Generally, piezoelectric materials are very difficult to process. If there is a slight improper processing, the surface and sub-surface of the workpiece will be damaged to varying degr...

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Problems solved by technology

However, the measurement results of nanoindentation technology are easily affected by the internal and external conditions of the test piece, such as the creep and thermal drift of the internal piezoelectric device will greatly interfere with the results

When measuring thin film specimens at the same time, the measurement results will be greatly affected by the substrate material

In addition, methods such as dynamic mechanical spectrum analysis technology, Brillouin light scattering technology, and acoustic scanning microscopy are also used in the measurement of Young's modulus of piezoelectric materials, but due to inconvenient operation, large errors, expensive equipment, and lack of Applicability and other factors cannot be widely used

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