Synthetic Process And Property Of High-entropy(Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)O Ceramics By Microwave Sintering

High-entropy ceramics usually refer to ceramic composites with simple crystal structure which are composed of five or more main components in equal molar ratio or close to equal molar ratio.In view of the excellent structural and functional properties of high entropy ceramics,they are widely used in mechanics,magnetism,electricity and so on,showing a good application prospect.This article uses the microwave sintering(Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)O typical system of high-entropy ceramic,changes in the process of the preparation process,microwave heating process,the variation of parameters such as temperature,reflected power To explore the microwave heating preparation(Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)O high-entropy synthetic mechanism of the ceramics.The main research contents and conclusions are as follows.In the experimental process,five metal oxides,MgO,CoO,NiO,CuO,and ZnO,were selected as raw materials for ball milling and mixing of raw materials according to the molar ratio of metal atoms.(Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)O high-entropy powder and high-entropy ceramics were prepared by microwave heating process.During the preparation of high entropy powder,the heating temperature ranged from 650°C to1200°C,each increase of 50°C,and the holding time was 30 minutes.In the process of preparing high-entropy ceramics,the sintering quality is selected as 10g,20g,and 30g,respectively.The sintering temperature was from 800 to 1200°C,and the temperature was increased by 100°C each time.XRD,SEM,EDS,DTA-TG and other means were used to characterize the formation process of(Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)O phase and analyze the phase formation mechanism.At the same time,mechanical properties such as bending strength and Vickers hardness were tested.High-entropy oxide powders of(Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)O with homogeneous and single chemical composition and rock salt phase structure were successfully synthesized by microwave heating process.The heating temperature ranges from 650°C to 1200°C,increasing by 50°C each time,and the holding time was 30 minutes.It was found that(Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)O composite materials could be synthesized within 1 hour under microwave heating above 850°C.The interaction between raw materials and microwave during the heating process,the microwave plasma effect,and the reaction sequence and synthesis mechanism of high entropy oxide ceramics ware discussed from the changes in input power and reflected power.In the microwave heating process,Mg O and Co O with rock salt react first,while wurtzite Zn O and tenorite Cu O react last.At the same time,the interaction between different ions in the raw material and the Jahn-Teller deformation under microwave irradiation were explored.(Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)O high-entropy ceramics were prepared by microwave sintering,and their density,porosity,and mechanical properties were characterized,including bending strength,and microhardness testing.The results show that at the same temperature,the density gradually increases with the increase of mass;When the mass is the same,the density first increases and then decreases with the increase of temperature,and the bending strength and microhardness also exhibit the same rule.When the mass is20 g and the temperature is 1000°C,the density reaches 92.87%,the bending strength is290±20 MPa,the elastic modulus is 187.05±5 GPa,and the microhardness is 681±18 Hv.