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Ohaya et al.13 showed that the addition of 5 wt-%MgO to aluminium titanate powder facilitated the preparation of T ialite was prepared from the chloride salts of fabricated bodies with improved mechanical strength. This aluminium and titanium via a urea formaldehyde was attributed to the formation of fine particles of corundum resin formation route. T ialite was readily formed at and spinel at the grain boundaries that prevented grain 1450-1500°C in bodies processed from powders growth and thus reduced microcracking. containing either 3 wt-%MgF 2 or 5 wt-%MgO added The work reported in the present paper aimed at the during resin formation. T he resultant material preparation of tialite by a urea formaldehyde polymeric withstood heat treatment at 1100°C for 24 h without route with the addition of stabilised MgO-ZrO 2 or Mg dissociation. In bodies prepared by mixing powders of ions, either in the form of oxide or fluoride, by powder MgO, MgF 2 , or a combination of both with polymer mixing as well as during resin formation as MgF 2 or prepared powder, the resultant tialite was less stable Mg(NO 3 ) 2 .6H 2 O. The powders obtained on calcination against dissociation.BCT /305 were studied and their stability examined.

Hwang 5 showed that addition of B 2 O 3 promoted the formation of a-cordierite. Misirli et al. 6 prepared porous Borate frit was added to a ceramic composition in alumina bodies of reasonable strength (245 MPa) suitable proportions between 3 and 10% (equivalent to for ceramic lters and ceramic-metal composites by adding 1-2%B 2 O 3 ) as a partial substitute for feldspar. Fuming between 0•5 and 1•5 wt-% B 2 O 3 to a-alumina. They showed silica, soda feldspar, and local bene ciated clay from that aluminium borate was completely formed at 1000°C, the Red Sea were the other components of the mix. with brous grain growth between 1000 and 1100°C. Zinc Mixes were fast red at temperatures between 1100 borates have also been used as a ux in porcelain bodies and 1250°C. T he addition of borate frit hindered the substituting for feldspars. Wala and Rosiek 7 found that the rate of dissolution of feldspar at temperatures up to ring temperature was lowered by 200°C and that the 1175°C, entering the structure of the mullite to form a density, exural strength, and thermal shock resistance of borate-mullite solid solution at 1200°C. T his phase the bodies were improved. Orlova et al. 8 showed that the occurs in 'swamps' of very ne acicular networks which sintering temperature and mechanical properties of alumina raise the modulus of rupture of the investigated mixes. porcelain bodies were reduced on adding 1 wt-% B 2 O 3 to Addition of 5% f rit (equivalent to 1-1•1%B 2 O 3 ) the batch composition. They attributed this to the presence improved the modulus of rupture without aVecting other of B 2 O 3 in the glassy phase, which enhanced crystallisation properties. Higher additions shortened the maturing and grain growth of the corundum to a grain size of range. BCT /491 20-40 mm. With the expansion in the construction of tile plants in T he authors are in the Department of Ceramics, Egypt, disposal of the sludge has become a problem requir-National Research Centre, T ahrir Street, 12622 Dokki, ing a solution. The tendency is to recycle sludge from such Giza, Egypt

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compositions, granite can be used in the range 15-40% for both conventional and fast ring regimes, whilst substituting M ica schist, a rock composed mainly of ne grained feldspars by rhyolite or felsite favours early maturing of the muscovite mica and quartz with orthoclase and microproduct. Also, the latter substitution leads to crystallisation cline feldspars as accessory minerals, was used to of mullite with much ner grains (<1-2 mm) than the use substitute feldspars from pegmatite in tile recipes. T he of granite, where grain size can reach 10 mm. When the rock is easily crushed and ground and contains a high accessory minerals separated from kaolin after bene ciation proportion of silica and potash ( 71 and 6•9% respect-(mainly mica) were used, no proper melt was recorded in ively) . Compositions containing 40% ne powder the mixes, and the presence of feldspar was found to be (<50 mm) were used. T he presence of feldspar and essential for the development of the ceramic bond in the quartz caused dissolution of the mica in the melt and red bodies. 9 Fiori and Fabbri 1 0 showed that additions of inhibited a tendency towards pinholing resulting from the same proportion of granite could be used for the separate melting of the mica grains. T he crystallisation production of red stoneware tiles in rapid ring cycles. of mullite doubled the modulus of rupture. Addition of Rhyolite has also been used to prepare glaze recipes by borate, however, reduced the content of mullite, which Bansagli and Szilagyi. 1 1 in turn decreased the modulus of rupture and caused In an attempt to recycle sludge byproduct in ceramic separate melting of the mica. BCT /547 plants, Ibrahim et al.1 2 studied the addition of 3-10% borate frit, equivalent to 1-2%B 2 O 3 , as a co uxing material Professor Ibrahim