Design And Research On Molding System Of Chalcogenide Glass

Traditional infrared devices have many shortcomings that cannot be ignored,such as complex preparation process,long production cycle,difficult preparation of large-scale devices,and low qualified rate,resulting in costly price during processing,thus largely limiting its engineering applications.Compared with the traditional infrared materials,the chalcogenide glass not only greatly expands the field of material design as well as the material selection range of the infrared optical system,but also it can overcome its disadvantages completely,and thus it has great application potential and industrial value.This paper systematically studied the design and molding process of sulfur-based glass molding system.Firstly,the equipment of chalcogenide glass molding system was designed and studied,and prefabricated parts of the chalcogenide glass were prepared.Meanwhile,The thermophysical and mechanical propertiesof the prefabricated parts were tested and analyzed by the XRD?X-Ray Diffraction?,DSC?Differential Scanning Calorimetry?,and Fourier transform infrared spectroscopy,density analysis and micro Vickers hardness tester Finally,the three-dimensional model of the mold and the molded glass blank was designed by ProE and Qform software,and the simulation analysis was carried out.The conclusions are as follows:The Ge₂₀Sb₁₅Se₆₅ glass prefabricated part perform with a surface diameter of 15 mm and no internal crystallization was prepared by salt bath quenching.By researching the design of the mold system and molding system of the sulfur-based glass,the H13 mold steel material was selected to manufacture the mold,the three-dimensional model of the mold was designed by ProE three-dimensional drawing design software,and then the special processing was used for manufacturing,and the adjustment was continuously improved according to the pressing situation.At the same time,titanium nitride was selected as thermal spraying material,infrared radiation heating method was selected,and different heating tube shapes and assembled heating systems were compared.Finally,a circular heating tube was selected and a heating system was designed,it was found that when the molding temperature is selected as 80?,the molding time is 5 mins and the holding time 5 mins too,it can lead to a good surface fineness.The thermophysical parameters of chalcogenide glass were systematically studied by various performance measurement methods.The heat flow curve of Ge₂₀Sb₁₅Se₆₅ glass was determined by DSC.Accordingly,the glass transition point,initial crystallization point and melting point temperature were determined as 273.9?,400.5?and 485?,respectively.The calculated enthalpy of fusion was 28.48 J·g^-1.According to the VFT equation,the ideal glass transition temperature T₀ is 464 K,wherein the specific heat difference between the liquid phase and the crystalline phase is?C_p=0.0969 J·K^-1·g^-1.The specific heat expressions of the supercooled liquid phase and the crystalline phase of the molded parts was measured by isothermal step method as:C_p^l=0.2922+0.0004297T+1.189T^-22 J·K^-1·g^-1,C_p^s=0.3721+0.0007716T+1.9992×10^-6T² J·K^-1·g^-1,at 300⁴00?and 100⁴00?respectively,the calculated specific heat difference between 300 and 400?of the glass equals 0.0933J·K-1·g^-1,which is basically consistent with the theoretical value(0.0969 J·K^-1·g^-1).the Gibbs free energy and the entropy curve were drawn by the calculated results of the specific heat,and the Kazman temperature was determined by the entropy curve as T_k=506.7 K.The transverse and longitudinal wave of Ge₂₀Sb₁₅Se₆₅ chalcogenide glass perform were tested by ultrasonic method,and the elastic modulus,shear modulus and Poisson's ratio were calculated as:14.97 GPa?7.25 GPa and 0.35,respectively.The Vickers hardness was measured by a micro Vickers hardness tester of 166.9 kg/mm².The molding process of chalcogenide glass was analyzed by theoretical simulation.In the molding process of the punch,when the molding rate is 50 mm/s,the flow stress distribution is the most uniform;and in the molding process of the die,when the molding rate is 40 mm/s,The flow stress distribution inside of the part is the most uniform;during the molding of the semi-faux mold,a relatively suitable molding rate is 60 mm/s.When the sample of molded prefabricated parts is a cylinder,the closer the diameter of the prefabricated parts is to the thickness of the molded parts,the smaller the molding stress is.In the process of molding,the lenses with different models were molded.The flow stress in the lenses increases with the increase of molding rate,and the slope of the increase of molding rate decreases gradually,and finally tends to be stable.