Processing Of Porous Ceramics By Starch Consolidation

Porous ceramics is a kind of ceramic material with lots of pores.It has excellent pHysical and chemical properties,so it is often used in chemical industry, petroleum, metallurgy,spin industry,pHarmacy ,food machine,cement and so on.However ,the present preparing methods of the porous ceramics have some disadvantages.A new method-starch consolidation for forming porous ceramics was developed using starch as both binder and pore former.It had been increasingly employed in preparing complex-shaped,near-net-shap advanced materials.In order to get a more effective preparing technology ,porous ceramics was fabricated by starch consolidation method in the paper.The fomula of porous ceramic powder can be derived from a lot of experiment on the comparison of the properties of green body and porous ceramics. In the paper ,preparation of a concentrated suspension with low viscosity and high solid content and stability is the key to success in starch consolidation technology.We studied the rheology of ceramic slip with low viscosity and high solid content.We found that the factors of quantity of the dispersant ,PH value of the solution ,the milling times ,the solid content ,the starch content etc.played an important role to viscosity of the suspension.The research results indicated that the dry shrinkage and compressive strength of green body were inverse proportion with solid content of the suspention.And the starch content had influence on the dry shrinkage ,sintering shrinking and compressive strength.By means of analysis of the TG-DSC of starch and green body,the appropriate sintering technology could be fixed on.It was an important directive signification to improve finished product rate.The amount of starch make distinct effect on the characters of porous ceramics.As the increasing of starch content ,it increased porosity,decreased the density and compressive strength:porosity from 52.31% to 65.02% ,density from 1.202g/cm3 to 0.873 g/cm3 ,compressive strength from 6.8MPa to 2.94 MPa. Porous ceramic materials with controlled porosity can be obtained by varying the starch content in the slip composition. In the paper ,the effects of some important factors including sintering temperature and holding time ,kinds and quantity of binder ,forming techniques on the properties of porous ceramics were researched and analyzed systematically. Through analysis the appearance of the porous ceramics by SEM ,we made sure that the porous ceramics had good pore structure.The simplicity of the process as well as the low price of starches makes this new starch consolidation technique very promising from an industrial point of view.