Study On Characteristics Of Iridium And Iridium Rhodium Alloy Temperature Sensors

Temperature is a physical quantity that characterizes the degree of hot and cold of an object,and temperature measurement plays a role that cannot be ignored in many fields,such as crop growth,chemical production,aerospace and other fields.With the improvement of aerospace technology,the upper limit requirements for temperature measurement are also getting higher and higher.Standard thermocouple temperature sensors can no longer meet the needs,and materials with high melting point and stable chemical properties are urgently needed to be used in temperature measurement in the aerospace field.After research and analysis,it is found that the iridium-rhodium alloy meets this characteristic.In order to find more suitable iridium-rhodium alloys with rhodium content,based on the first-principles method of density functional theory,the iridium-rhodium alloys were modeled and analyzed.According to the simulation test results,a more suitable iridium-rhodium alloy wire was selected to prepare a thermocouple temperature sensor for analysis.In this paper,based on density functional theory,the crystal structure,elastic constant and other characteristic parameters of pure metal iridium and pure metal rhodium are studied,which can provide reference for the modeling of iridium-rhodium alloys with different rhodium contents.The crystal structure modeling adopts the virtual crystal approximation method.At the same time,the crystal structures,lattice constants and elastic constants of iridium-rhodium alloys with different rhodium contents were analyzed,so as to provide a reference for the use of iridium-rhodium alloy thermocouple temperature sensors.The main calculation results are as follows:1.Establish the crystal structure models of pure metal iridium and pure metal rhodium,optimize their geometric structures,and adjust specific calculation parameters,such as exchange correlation energy approximation,plane wave pseudopotential method,etc.comparison of experimental parameters.According to the experimental results,the calculation parameters were selected to calculate the characteristic parameters of iridium-rhodium alloys with different rhodium contents.2.The crystal structure models of iridium-rhodium alloys with different rhodium contents are established based on the virtual crystal approximation method.During the calculation and simulation process,the calculation parameters refer to the calculation parameters of pure metal iridium and rhodium.The characteristic parameters of energy band structure and density of states of iridium-rhodium alloys with different rhodium contents were studied.The analysis results show that the energy band structure of iridium-rhodium alloys varies with the content of rhodium.Ir Rh10,Ir Rh20,Ir Rh40 and Ir Rh80 alloys are selected to calculate the work function.The work function calculation results show that the work functions of Ir Rh10,Ir Rh20 and Ir Rh80 alloys are relatively close and higher than that of iridium rhodium 40 alloy,so the thermoelectric potential of the material used as a thermocouple temperature sensor should be the highest.3.Thermocouple temperature sensors prepared from iridium,iridium-rhodium 10 alloy,and iridium-rhodium 40 alloy respectively,build a temperature field platform with a temperature range of 300?-2100?,and study the characteristics of the thermocouple temperature sensor.The results show that at the same temperature,the thermocouple made of iridium-rhodium 40 alloy wire and iridium is higher than the thermocouple temperature sensor made of iridium-rhodium 10 alloy wire and iridium wire.The iridium rhodium40-iridium thermocouple temperature sensor has better performance in many test experiments.It is consistent with the calculation and simulation results,and has reference significance for the selection of thermocouple temperature sensor.