Fabrication and characterisation of porous mullite ceramics from high voltage insulator waste

Abstract

High voltage insulator waste (HVIW) eliminated from high voltage transmission lines was used in the preparation of porous mullite ceramics. The fabrication and characterisation of porous mullite ceramics are described. The relationship between phase transitions, sintering temperature and physicochemical properties of the porous mullite ceramics are analysed and compared. The results show that the complex properties are the best when the mass ratio of HVIW/clay is 4 : 1, the amount of pore former is 500 mL kg 21 and the sintering temperature is 1500uC, the cold crushing strength reaches 4?8 MPa. Increasing the sintering temperature could strengthen the specimens. The average pore diameter of the specimens enlarged with the increasing sintering temperature. Meanwhile, the crystalline and morphology of mullite grains advanced and the maximum grain diameter reached to 1?5 mm. This improvement was attributed to the fact that complex properties of specimens could be optimised by new formation of new mullite phase.

Effect of sintering temperature and time on preparation of ceramic tiles made from tungsten tailings

“…The liquid phase in the samples allows the interconnected pores to be filled up and contributes to the increase in the densification and the decrease in the porosity of the specimens. 23 Whereas at 1100uC, larger closed pores are presented, some pores even have sizes bigger than 100-150 mm. As indicated by the XRD analysis (Fig.…”

Effects of Aggregate Content on the Interconnected Pore Formation and Properties of Porous Purging Plug Materials

“…The interconnected pore structure can be formed through the techniques mentioned below, including direct foaming [3][4][5][6], replica templating [7], adding poreforming agents [8][9][10] and so on, but the pore size by direct foaming and the replica template method is much bigger than what would be suitable to be used in steel-making applications. The method of incorporation of pore-forming agents with ceramic powder results can yield a porous structure of closed or poorly interconnected pores.…”

Effects of firing temperature on the microstructures and properties of porous mullite ceramics prepared by foam-gelcasting

“…8,9 Porous mullite ceramics containing 61.1-67.8 and 67.6-77.8% porosities and having compressive strengths of 2.7-4.8 and 3.3-32.4 MPa were prepared respectively by using the first two techniques. 5,6 When the third technique was used, mullite ceramics containing lower levels of porosity (27-54%) but having much higher bending strength (10-85 MPa) could be prepared. 7 In the case of using the last technique, porous mullite ceramics having similar levels of porosity and compressive strength to those in the case of using the second technique could be produced.…”

“…Various methods were used to fabricate porous mullite ceramics, including sacrificial template, 5 gelcasting, 6 reaction bonding 7 and freeze casting. 8,9 Porous mullite ceramics containing 61.1-67.8 and 67.6-77.8% porosities and having compressive strengths of 2.7-4.8 and 3.3-32.4 MPa were prepared respectively by using the first two techniques.…”