Study On The Microstructure And Thermal Energy Storage Properties Of 52Ni-42Si-6Al Alloy

With the continuous development of human society,the problem of energy is becoming more and more serious.As a kind of sustainable clean energy,solar energy has been paid more and more attention.Recently,although concentrated solar thermal power technology is becoming more and more mature,there are some contradictions between the production and consumption of heat in time and space.As an important solution to solve this problem,thermal energy storage technology can improve the efficiency of energy utilization and realize high-efficiency thermal energy storage.In the field of medium and high temperature thermal energy storage,metal and its alloy are used as thermal energy storage materials with obvious advantages.Some metal phase change thermal energy storage materials are suitable for solar thermal power generation thermal energy storage system because of their proper phase change temperature,large energy storage density,high thermal conductivity and small change of phase change volume.In this paper,52Ni-42Si-6Al phase change thermal energy storage material was designed and prepared.The microstructure and phase of the material were analyzed by metallographic microscope,scanning electron microscope and X-ray diffraction analyzer.It was found that the phase of 52Ni-42Si-6Al ternary eutectic alloy was composed of three phases:?₁(Al Ni₂Si),Ni Si and Ni₃Si₂.The granular Ni Si phase was uniformly distributed in the matrix of?₁(Al Ni₂Si).The phase transformation temperature,latent heat,specific heat,thermal diffusivity and thermal conductivity of the tested materials were studied by using differential scanning calorimeter and laser thermal conductivity meter.It was found that the 52Ni-42Si-6Al phase change material with density of 6.065 g/cm³ began to melt at about 920.5?,and its latent heat reached 233.2 k J/kg,with high thermal conductivity.Based on the vacuum thermal cycling experiments of 52Ni-42Si-6Al phase change material,it is found that the phase change temperature and density of 52Ni-42Si-6Al eutectic alloy do not change after 1000thermal cycles,the latent heat of phase change gradually decreases from 233.2 k J/kg to 204.8k J/kg,and its microstructure also becomes coarse.After long-term thermal cycling,52Ni-42Si-6Al alloy still has high thermal conductivity,and its properties are excellent The thermal conductivity at constant temperature first increases and then decreases with the increase of the number of cycles,and reaches the maximum at 750 thermal cycles.The compatibility test of 52Ni-42Si-6Al phase change thermal energy storage material and aluminum oxide at high temperature shows that there is no obvious corrosion and damage on the alumina crucible,and the container made of alumina can be compatible with52Ni-42Si-6Al phase change thermal energy storage material for a long time during the thermal cycle.Therefore,52Ni-42Si-6Al phase change thermal energy storage material can be used as phase change thermal energy storage material at about 1000?in solar thermal power generation system.