Method for measuring coating thickness and interfacial roughness simultaneously by ultrasonic

Abstract

The invention discloses a method for measuring coating thickness and interfacial roughness simultaneously by ultrasonic and belongs to the technical field of ultrasonic nondestructive test and evaluation for materials. The method adopts an ultrasonic pulse echo detection system which comprises a sample table, an interfacial roughened coating sample, a delay block probe, a flow detector, a digital oscilloscope and a computer. Aiming to solve the difficult problem about measuring thickness and roughness of the nondestructive characterization interfacial roughened coating, the method includes deriving a sound pressure reflection coefficient amplitude spectrum / r(f;rq,d) / of the interfacial roughened coating structure, performing correlation operation to theoretical and experimental sound pressure reflection coefficient amplitude spectrums of different frequency bandwidth to obtain thickness di and roughness Rqi of the coating corresponding to the maximum correlation coefficient eta<max>(Rq,d) of each bandwidth, averaging thickness and roughness measured within different frequency windows to obtain mean d and mean Rq which are respectively the coating thickness and the interfacial roughness needed to solve. The method fills a gap in the coating thickness and roughness nondestructive characterization methods.

Description

technical field [0001] The invention relates to an ultrasonic method for simultaneously measuring the thickness of a coating layer and the roughness of an inner interface, which belongs to the technical field of ultrasonic nondestructive testing. Background technique [0002] Practice has shown that interface roughening is an effective measure to improve the bonding strength of the interface, and it is also an effective measure to improve the stress impact resistance, thermal corrosion resistance and service life of the coating layer during service. The degree of roughness directly affects the interfacial bonding strength, interfacial residual stress, and the degree of interface oxidation, etc., and the residual tensile stress caused by roughness may lead to cracking and peeling of the coating layer, which means that interfacial roughness not only enhances interfacial bonding, but also introduces Factors that are unfavorable to the life of the interface. Therefore, reasonab...

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Problems solved by technology

However, none of the above methods are suitable for the roughness measurement of the coating layer and the substrate interface.

The preparation process of the coating layer will also lead to changes in the surface roughness of the substrate. When there is roughness in the inner interface of the coating layer, it is difficult to characterize its thickness and roughness. reports for effective characterization

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