| Mullite whiskers are widely used as reinforcements in composites due to their special crystal structure and excellent properties.In recent years,with the high value utilization of solid waste has become a research hotspot,the research of mullite whisker preparation with different solid waste has appeared at home and abroad.In this paper,mullite whiskers were successfully prepared by molten salt method with silica dust and alumina slurry as main raw materials,and the synthesis process was systematically studied.The crystal structure and micro morphology were studied by X-ray diffraction（XRD）,infrared spectroscopy（FTIR）,field emission scanning electron microscopy（FESEM）and transmission electron microscopy（TEM）,the results are as follows（1）Mullite whiskers were prepared by molten salt method with silica powder and dust ash as silicon source and aluminum sulfate octadecyl hydrate as aluminum source.Through sample analysis,the process parameters of mullite whisker synthesis were obtained as follows:calcination temperature 1000℃,calcination time 3h,molten salt type Na2SO4,molten salt ratio 1.2:1,and the length diameter ratio of mullite whisker was 20～40.It is found that the initial temperature of Mullitization is lower than that of dust.（2）The physicochemical properties of waste slurry from aluminium air batteries were analyzed,including p H value,solid content,chemical composition and mineral composition.The occurrence of Al in waste slurry was studied.It was found that Al in waste slurry existed mainly in the form of KAl O2.On this basis,the technological route of mullite whisker synthesis using waste slurry as aluminum source was explored:firstly,the waste slurry was pretreated to convert it into aluminum potassium sulfate solid,and then aluminum potassium sulfate was decomposed at high temperature to produce Al2O3and K2SO4,which were used as aluminum source and molten salt for mullite whisker preparation respectively.（3）Based on the relevant properties of waste slurry,mullite whiskers were prepared by molten salt method with silica powder as silicon source,aluminum sulfate octadechydrate and waste slurry as aluminum source respectively.Through sample analysis,the process parameters of mullite whiskers synthesized by waste slurry were obtained as follows:calcination temperature 950℃,calcination time 3h,adding molten salt K2SO4and molten salt ratio 0.8:1 The ratio of whisker length to diameter is 8～40.It is found that the preparation temperature of waste slurry system is low and the amount of molten salt needed is small.（4）Mullite whiskers were prepared by molten salt method with dust and waste slurry as main raw materials.Through sample analysis and research,the process parameters of synthesizing mullite whiskers from dust and waste slurry were obtained as follows:calcination temperature 950℃,calcination time 3h.When molten salt K2SO4is added and the ratio of molten salt is 0.8:1,the length diameter ratio of mullite whiskers is 4～20.It is found that the calcination temperature,calcination time and the amount of molten salt all have a great influence on the experimental results;the high temperature,the long time and the excessive content of K element in the raw materials are easy to produce heterophase.（5）The growth of mullite whiskers in porous mullite matrix was studied.The better mixing ratio was selected:n（Al2O3）:n（Si O2）=3:2,m（Na2SO4）:m[Al2（SO4）3+Si O2]=1.2:1.The microstructure showed that mullite whiskers were obtained in the pores of mullite matrix,which explored a new way for mullite whisker reinforced porous materials. |
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