In o rde r to reduce energy consumpt ion , a t t empts are now being made at add ing at t i t ives to ceramics. In the previous studies we have observed tha t add i t i on o f a small percentage o f addi t ivies such as glass, r ice-husk ash and wol las toni te to porce la in can reduce the firing t empera tu re of the t r iaxial body to a grea t extent [1, 2]. In this let ter the effect o f add i t ion o f glass, r ice-husk ash and wol las toni te on the s t rength and bond ing o f porce la in has been observed. A t t e m p t s have been made to app ly the Spr igg 's equa t ion for the s t rength o f such compos i tes and s t r e n g t h d e n s i t y dependence is observed. The fracture surfaces o f these composi t ies have been observed by scanning e lec t ron microscopy . China clay, flint, ball clay, waste glass powder and wol las toni te were ob t a ined f rom different sources and their chemical analysis was pe r fo rmed using the wet chemical analysis m e t h o d (Table I). Rice husk ash was p repa red by firing washed rice husk. R a w mate r ia l s were separa te ly g r o u n d to pass t h rough a 200 mesh B.S. Sieve. The conven t iona l porce la in mix (china clay 50%, fe ldspar 25% and flint 25%) was taken as the base mater ia l . Different po r t ions o f r ice-husk ash, glass and wol las ton i te were a d d e d to the porce la in (Table II) . The specimens were p repa red in the form o f rods by slip cast ing, using p las ter o f par is moulds . To ob t a in the p rope r consis tency o f the slip, a small quan t i t y o f e lectrolyte (1 :1 ra t io sod ium ca rbona t e and sod ium silicate mixture) was found essential in each case, bu t the a m o u n t var ied with the compos i t i on o f the body . The specimens were dr ied at 110 ° C for 48 h and were fixed at different t empera tu res between 1000 and 1200 ° C in
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May 1, 2004
Sue Miles 
Open Access