Study On Fused Silica Ceramics Prepared By Gel-gasting

Fused silica ceramics are widely used in the fields of aviation,electronics and solar energy because of their excellent thermal shock resistance,low thermal expansion coefficient and low thermal conductivity.However,the quartz ceramics prepared by traditional processes are generally low in density,High porosity defects,hindering its wider application.In this paper,the process of preparing high-strength and high-density fused silica ceramics by coagulation process is studied systematically,and the influencing factors of ceramic green preparation and sintering process are optimized and improved.In this study,high purity fused silica powder as the main raw material,the use of low toxicity of HEMA/TMPTA system,dispersant is NH4 PAA,APS is initiator and TEMED is a catalyzer,and Si₃N₄ were used as sintering aids and sintered by microwave sintering furnace,respectively.The pH value,initiator and catalyst were 5Vol% ammonium persulfate solution（APS）The samples were tested and analyzed by the method of characterization of ceramic slurry,combined with universal material testing machine,XRD,SEM and electron density densities.The results show that when the solid content of the slurry is 60vol%,the pH value is 4,the amount of the dispersant is 1.5wt% and the ultrasonic vibration time is20 min,the dispersibility and fluidity of the slurry are the most stable.The ratio of monomer to crosslinking agent is 2: 1 and the initiator dosage is 0.2wt%.The curing time is 30 min,and the flexural strength of green body can reach 16.5MPa.When microwave sintering is used,Si₃N₄ additive.When the heating rate is 20℃/min,the sintering temperature is 1150℃ and the holding time is 2h,the bending strength of the sample can reach 36.3MPa and the bulk density can reach 1.98g/cm 3,the performance has been further improved,the experiment achieved the desired results.