Design And Analysis Of ZnS Coating Fixture Based On Thermal-Structural Coupling

There will be more than 100℃ in the process of optical coating.The substrate and the coating fixture usually produces thermal stress,while the film also generates a film stress.So the coating equipment slowly rising temperature to the specified temperature,holding several hours after the end of the coating to be slowly cooled to 60℃.The crack or damage on the surface of the base is usually caused by thermal stress.This paper takes Yunnan X photonics Co.,Ltd with Φ208mm multi-spectral ZnS substrate plating antireflection coatings as the research object.In this paper,a series of research work on the stress avoidance and reduction of the ZnS substrate and the coating fixture is carried out,which provides theoretical basis for practical production.The main research work is as follows:(1)The geometric configuration,coating fixture structure and material with uniformity of layer thickness,ZnS effective aperture,linear expansion coefficient,corrosion resistance,cutting machining,economy,revolves of bracket bearing capacity and fixture storage of selection principle.Finally the geometric configuration of the planet rotating fixture,which is parallel to the axis of rotation,the structure of universal reverse hanging type coating fixture,the 1050 alloy,2A02 alloy and 2A12 alloy are simulated by finite element method.(2)Base on 3D model of Solidedge with 208mm multi-spectral ZnS and three kinds of coating fixture.According to the actual production process of the coating process,the pretreatment parameters are set up.The finite element software ANSYS is used to simulate it.Pre-processing using module Preprocessor.The simulation of ZnS substrate coating process is performed using Solution.The effective stress cloud fringe distribution and the maximum deformation of the ZnS substrate and the coating fixture are obtained.It is concluded that the structure of universal reverse hanging type coating fixture and the 2A12 alloy coating fixture material are the best coating combination.(3)The optimal coating composition is improved two times to ensure the integrity of the ZnS substrate,and then the three groups of coating experiments are carried out to verify.Finally,the transmittance and reflectivity of ZnS substrate were tested.On the surface of the film do the micro test and environmental test.This test results meet the technical requirements of infrared window and GJB 2485-95 general specification for optical coatings.In order to achieve the purpose of ZnS substrate not broken.(4)In order to assist the designers through the combination of computer simulation software for a relatively scientific coating fixture structure and material,so as to reduce the losses caused by waste or defects in the coating process.At the same time,the original coating fixture structure and materials are fine tuned.Several kinds of coating fixture structure and material are provided for reference.