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.

In the presence of N 2 and CO gases, MgAl 2 O 4 -Ti(C,N) composite has been synthesised by aluminothermic reduction. The phase characterisation and microstructure of this novel composite were investigated by powder X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The results show that the nitridation reaction begins at 1100uC. With an increase of temperature, TiC starts to appear and forms Ti(C,N) solid solution with TiN; the grain size of Ti(C,N) grows with increasing temperature and the final product is MgAl 2 O 4 -Ti(C,N).MST/6150