Research On The Mechanical Properties And Sintering Behavior Of Magnesia Ceramics Consoildated By Spark Plasma Sintering

Magnesium oxide ceramic is a typical high-temperature ceramic material having a melting point of 2800℃,a boiling point of 3600℃,a Young’s modulus of 300 GPa,and a Mohs hardness of 6.The main applications are in the fields of metallurgy,military,and aerospace.However,due to its large coefficient of thermal expansion,the sintering performance is poor,which limits the application of magnesium oxide ceramic materials.Densification sintering is one of the key scientific issues in the preparation of magnesium oxide ceramic materials.As a new sintering technology,spark plasma sintering has the characteristics of fast sintering speed,short sintering time and high sintering pressure.It has been widely used in the research and preparation of nanomaterials,transparent ceramics and difficult-to-sinter materials.In this study,nano-magnesia powder and nano-alumina powder were used as composite additives,and magnesium oxide ceramics and magnesia ceramic composite ceramics were prepared by spark plasma sintering technology.Sintering and mechanical properties of magnesia ceramics and magnesia ceramic composite ceramics prepared by spark plasma sintering.Through the above research work,the following main conclusions can be obtained:（1）Using the spark plasma sintering,when the sintering temperature was 1400℃,the density of the magnesium oxide ceramic sample is the highest,about 98.19%.The grain size is about 7.64μm.When the sintering temperature is 1375℃,the mechanical properties of the magnesium oxide ceramic sample are the highest.The maximum bending strength is about 211.32±15.83 MPa,and the maximum hardness is about 6.83±0.42 GPa.（2）The 2wt.%SiO₂-MgO ceramic sample was prepared at 1400℃and 30 MPa,the relative density was 99.98%,the maximum flexural strength was about253.99±7.47 MPa,and the maximum hardness was about 7.56±0.21 GPa.（3）The MgO-SiO₂-Al₂O₃ multiphase ceramic was prepared at 1400℃and 30MPa.The relative density was 99.85%,the maximum flexural strength was about269.6±9.22 MPa,and the maximum hardness was about 12.51±0.29 GPa.