| Nowadays,energy saving and emission reduction become the theme of social development.The establishment of the carbon perking and carbon neutrality goals target has put forward clear requirements for the development of various industries in China.Especially in high-temperature industries,it is necessary to improve production efficiency and reduce energy consumption.Therefore,advanced heat insulation materials must be developed to strengthen the thermal insulation effect of kiln body and reduce heat dissipation loss.Porous ceramic materials contain a large number of pores and have the advantages of low bulk density,high porosity,high strength,low thermal conductivity,high temperature resistance,and bulk stability,which are suitable as kiln insulation materials.In this study,mullite-zirconia porous ceramic materials are prepared with kyanite,andalusite and sillimanite as the main raw material.The study will provide theoretical and technical basis for the preparation and precise control of the structure of high-performance porous materials,and lay a foundation for further guiding production.It is also of great significance for energy saving and emission reduction,efficient utilization of mineral resources and promoting the research and development of a new generation of high-performance refractory materials in China.In this study,mullite porous ceramic materials with high-temperature industry were prepared by one-step foaming and in-situ sintering process using kyanite,andalusite and sillimanite as the main raw materials andα-alumina as the auxiliary material.Systematically studied the raw slurry solids content,alumina content and sintering temperature on kyanite based,andalusite based and sillimanite based mullite porous ceramic material physical properties,phase composition and microstructure of influence law,set up effective regulatory mechanism,structure and performance of their formation mechanisms,optimizing the suitable raw material composition,solids content and sintering temperature.Then on the basis of the above research,the introduction of zircon,monoclinic zirconia and corundum,respectively,to prepare mullite-zirconia porous ceramic materials,systematically studied the types of zirconia sources and the effects of the amount of zirconia on the properties,composition and microstructure of the samples,and clarified the mechanism of zirconia strength and toughness.Studies on the preparation of kyanite-based mullite porous materials with kyanite andα-alumina as the main raw materials shows that:the bulk density and compressive strength of the samples gradually became larger with the increase of the solid content,the pores of the samples gradually decreased.With the increase of alumina content,the bulk density and compressive strength of samples gradually increase,while the intensity of mullite diffraction peak increases.With the increase of sintering temperature,the bulk density and linear change rate of the samples decrease first and then increase,the mullite diffraction peak gradually increased,and mullite grows by two-dimensional nucleation mechanism.When the solid phase content is 55vol%,alumina content is 60%,and sintering temperature is 1500℃,the comprehensive performance of the sample is better,and its bulk density is 0.49 g·cm-3,compressive strength is1.02 MPa,linear change rate is-2.07%,and the linear change rate on reheating is-1.65%.The study on the preparation of andalusite-based mullite porous materials with andalusite andα-alumina as the main raw materials shows that:with the increase of solid phase content of slurry,the bulk density and compressive strength of the samples increase gradually,the strength of mullite diffraction peak increases first and then basically remains unchanged,and the pore size of the samples becomes smaller and the pore wall becomes complete.With the increase of alumina content,the bulk density and compressive strength of the samples decrease first and then increase,the linear change rate on reheating increases gradually,and the diffraction peak of mullite increases gradually.With the increase of the sintering temperature,the density and linear change rate of the samples first decrease and then increase,and the diffraction peak of mullite gradually increases,and the crystal changes from needle-columnar-like to short-columnar-like,and then forms steps.When the solid content of the solid phase content is 55vol%,the alumina content is 65%,the sintering temperature is 1550℃,the comprehensive properties of the samples are better,the bulk density is 0.53 g·cm-3,the apparent porosity is80.63%,the compressive strength is 1.44 MPa,the linear change rate is-1.15%,the linear change rate on reheating under 1500℃×24 h is-0.1%.The study on the preparation of sillimanite-based mullite porous materials with sillimanite andα-alumina as the main raw materials shows that with the increase of solid content,the bulk density and compressive strength increase,and the pore size decreases and the particle bonding becomes compact.With the increase of alumina content,the bulk density and compressive strength of samples increase,while the intensity of mullite diffraction peak decreases.With the increase of sintering temperature,the bulk density decreases first and then increases,the diffraction peak intensity of mullite increases,and the grain becomes coarser and forms stepped morphology.When the solid phase content of the slurry is 55 vol%,alumina content is 65%and calcination temperature is 1600℃,the comprehensive performance of the sample is better,with bulk density of 0.57 g·cm-3,apparent porosity of 81.56%,compressive strength of 2.95 MPa,the linear change rate is-6.06%and the linear change rate on reheating under 1500℃×24 h is-0.07%.Based on the above research optimization,kyanite andα-alumina as main raw materials,adding different source of zirconium,preparation of mullite-zirconia porous materials,the results showed that when zircon is used as zirconium source,the bulk density and compressive strength of samples decrease first and then increase with the increase of the amount of zircon,Zirconia is uniformly distributed at mullite grain boundaries.When monoclinic zirconia is used as zirconium source,the bulk density and compressive strength of samples increase gradually,the apparent porosity and linear change rate decrease gradually,the diffraction peak of zirconia increases gradually,and more spherical zirconia particles are evenly distributed among mullite grains.When AZ40 is used as zirconium source,the bulk density and compressive strength of the samples decrease first and then increase with the increase of its dosage,while the change trend of apparent porosity is opposite.The intensity of the diffraction peak of mullite decreases and that of zirconia increases gradually.When AZ40 is used as zirconium source and the dosage is 14 wt%,the enhanced effect is obvious,the comprehensive performance is better,the compressive strength is 3.85 MPa,the bulk density is 0.46 g·cm-3,the apparent porosity is82.97%,and the linear change rate is 1.02%. |
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