Preparation And Application Investigation Of Mechanoluminescence Materials

Mechanoluminescence（ML）,a special luminescence phenomenon,is the light emission caused by external stimulus,such as compression,stretching,bending,impact,friction,etc.The mechanoluminescent phenomenon can be divided into destructive mechanoluminescence,plasticmechanoluminescenceandelastic mechanoluminescence.Among them,the elastic mechanoluminescence materials possess many advantages,including repeatable,fast response,high luminous intensity,wide range of stress response and so on.In addition,in the elastic deformation range,the mechanoluminescence intensity is proportional to its deformation size,achieving real-time visual display of the stress distribution,which makes it possible that the mechanoluminescence materials are used as a sensor for detecting the structural damage,fractures,and deformation.In order to further study the application value of mechanoluminescence materials in the detection of welding defects,we have developed a new kind of mechanoluminescence material and researched the properties of this materials.The main contents of this study include the following three aspects:（1）A cyan mechanoluminescence material Ba₂Zr₂Si₃O₁₂:Eu²⁺,Dy³⁺has been prepared successfully.The XRD refinement results shows that Ba₂Zr₂Si₃O₁₂:Eu²⁺,Dy³⁺is a piezoelectric material belong to P2₁3 space group.Fluorescence spectra show that the emission peak is located at 516 nm and the bright cyan emission belongs to the5d-4f electric dipole transition of Eu²⁺ions.At the same time,the effect of different doping concentrations on the luminescence properties was studied.The results of stress test show that when the doping concentration is 3%,the sample possesses the best mechanoluminescence performance and the mechanoluminescence intensity can be seen by the naked eye,which shows that it has a potential application in stress detection.（2）Mechanoluminescence materials Sr_0.975Al_1.97O₄:Eu_0.025,Ho_0.075（SAOEH）have been prepared by the high temperature solid-state method.The XRD,fluorescence spectra and afterglow curves of SAOEH were measured.The prepared SAOEH samples were mixed with the transparent resin in proportion to prepare mechanoluminescence thin films with different thicknesses,then they were applied to the welding defects detection of steel plates.The results show that the stress intensity of the luminescent film increases first and then decreases with the increase of the film thickness,and the suitable thickness is 0.9 mm.Under the same conditions,the mechanoluminescence thin film can have the responses to the different tensile strength sizes and different tensile strength speeds.（3）In order to investigate the visualization properties of mechanoluminescence films（SAOEH）on the welding defect,we have tested the performance of steel-based mechanoluminescence films with a lab-built system.Particularly,we have found that the mechanoluminescence films has a good response to the applied load after a simple test.The stability test showed that the mechanoluminescence films possess a stable luminescence output under the repeating load.What’s more,the mechanoluminescence films could be highly sensitive to the defects on the back of the steel sheet.By using CCD camera and origin8.5,the stress emission images of the films were collected and the results showed that the mechaoluminescence films could display the stress distribution on the steel plate surface and its relative size in real time.