Preparation And Properties Of Porous Gradient Ceramics From Diatomite

The application of porous ceramic materials in water purification,beverage purification,medicine,bioengineering and other industries has gradually become an important part in the sustainable development of modern industrial production.Diatomite,known as the "natural molecular sieve",which has a natural micro-porous structure,is a good material in the preparation of filter aid,porous ceramic materials.However,the present diatomaceous porous ceramic materials have disadvantages of low strength,poor permeability and low separation efficiency,which seriously restricts their application in the field of porous materials.In recent years,the design concept of porous gradient materials has been widely applied in the production of various functional materials.Preparation of porous gradient ceramics by diatomite as raw material has an important significance.In this study,porous gradient ceramic is prepared by formula adjustment and taking diatomite as the main raw material,mixing lithium carbonate and wollastonite as sintering agent.The porosity gradient porous ceramics with high mechanical strength and high selectivity has a layer-by-layer structure.By analyzing the phase,morphology,mechanical properties and filtration performance,the impact of sintering temperature and the content of pore-forming agent on the properties of mechanics and filtration were invested.The results of the study are as follows:1.The sintering temperature has an important effect on the pore structure of diatomite.When the sintering temperature is lower than 1100 ?,the porosity gradient porous ceramics has good porosity,but its mechanical strength is too low to be applied practically.When the sintering temperature is controlled at1100 ?~1140 ?,the pore structure of diatomite particles can be retained to the maximum,and the porous ceramics have certain mechanical strength.When the sintering temperature is higher than 1140?,the prepared porous ceramics have good mechanical strength,the natural pore structure is destroyed.Therefore,considering the effect of sintering temperature on the strength and porosity of porous ceramics,the optimum sintering temperature is 1140?.2.A pore gradient ceramic,which has a layer-by-layer structure,was successfully prepared.The porous gradient ceramic,whose bending strength is 22.5 MPa,is made up of a porous support layer and a separation layer.The porosity of the separation layer is 55.43% and the pore diameter is 0.2~0.8?m.The porosity of the support layer is 59.05% and the pore diameter is 8 ?m~20 ?m.3.The effects of the amount of lithium carbonate and wollastonite on the sintering properties of the support were studied.With lithium carbonate as the combustion agent,the strength of the support was effectively improved.Lithium carbonate becomes liquid at low temperature and undergoes sintering reaction with the oxide in the blank to produce dense Li Al Si3O8 phase,which greatly improves the strength of the support.Wollastonite has a low volume effect at sintering.By controlling its addition amount,it can effectively control the bulk effect of sintering.4.The filter accuracy of the ceramic was tested.It had a retention rate of 99% for particles having a particle size greater than 5 ?m and a retention rate of 97% for particles having a particle size of 2 ?m.