Study On The Influence Of Nitrogen On The Properties Of Fused Quartz Ceramics

Fused silica ceramics have excellent physical and chemical properties,are widely used in many kinds of structural materials and functional materials,However,because the molten quartz ceramics are easy to crystallize during the sintering process,the strength of the blank is not high,which cannot meet the requirements of quartz ceramics in different fields.Therefore,it is of great significance to improve the mechanical strength of quartz ceramics and meet the performance requirements of quartz ceramics in different fields.Gel-casting is one of the common forming methods of quartz ceramics,and it has the characteristics of high strength of forming blank,small sintering yield of processed sample,simple operation and broad application prospect.In this paper,quartz ceramic green and composite green were prepared by gel-casting,which provided experimental conditions for later experiments.In order to improve the phenomenon of low strength and low performance of quartz ceramics caused by crystallization,loss of organic matter and low sintering temperature,this paper adopts the method of nitrogen sintering at high temperature and nitrogen element introduction in situ through carbonization reduction nitrification reaction to improve the performance of quartz ceramics.The results show that the volume density of fused quartz ceramics can reach 2.09g/cm³ and the compressive strength can reach 61MPa by using nitrogen sintering at 1450?.And the pure quartz billet prepared by injection condensation type can be carbonized in high temperature nitrogen without degreasing,and the quartz billet can be directly carbonized in nitrogen.Through the high temperature nitriding of pure quartz green at 1400-1500?,the samples after nitriding were characterized,the results showed that there was a small amount of fibrous substance in the samples after nitriding at different temperatures,and the nitriding effect was not obvious.Si/SiO₂ composite billets with Si content of 5%were prepared using a low-toxicity gel system,and the resulting billets were sintered at high temperature in nitrogen to synthesize Si₂N₂O in the central position of the fused silica ceramic matrix.The influences of in situ synthesized Si₂N₂O on the microstructure and mechanical properties of fused silica ceramics were studied.The results show that Si/SiO₂ composite billets can be used to synthesize spike-like and fibrous Si₂N₂O in situ in nitrogen at 1450°C.Si₂N₂O synthesized in situ can improve the mechanical properties and microstructure of quartz ceramics.When the Si/SiO₂ composite billet is sintered in nitrogen at1450°C for`120 min,the volume density and bending strength of the quartz ceramics can reach 2.36 g/cm³ and 114.37 MPa,respectively.