Hot corrosion behavior of slip-cast alumina-chrome refractory crucible against molten glass M. Nath, K. Dana, S. Gupta and H. S. Tripathi * Alumina-chrome bodies were prepared by slip casting route. Slip casted bodies were sintered in the temperature range of 1550–1650 8C in reducing atmosphere with 2 h soaking time at peak temperature. Highly dense alumina- chrome body with bulk density 4.24 g/cc and almost zero apparent porosity were obtained at 1650 8C. The hot corrosion test of alumina-chrome crucible against borosilicate glass was carried out in static condition at 1200 8C for 4 h. The study of the glass–refractory interface after static corrosion test was done by scanning electron microscopy, energy dispersive X-ray spectroscopy analysis and X-ray diffraction (XRD) analysis. The XRD pattern of glass–refractory interface does not show formation of any new phases. Elemental mapping of glass–refractory interface indicates corrosion up to a depth of 70 mm has taken place in the form of ion migration. 1 Introduction Alumina-chrome refractories are very well known for their high chemical stability and outstanding corrosion resistances against molten glass and slags. And for these properties, it has been used for years in the field of various types of furnaces as castables and shaped refractory. Those properties also make them useful in gasifiers, incinerators, and in some vitrification processes too [1–5]. The corrosion resistance of any ceramics is considered to depend mainly on two major factors, which are (a) their solubility and (b) relative density and apparent porosity of the sintered body. Alumina-chrome refractory shows high chemical stability and corrosion resistance due to the extremely low solubility of chromic oxide in molten salts/slags. So, highly dense alumina-chrome refractory with minimum porosity should be excellent corrosion resistant against the molten glass. But, it is very difficult to sinter alumina-chrome body near to its theoretical density [2, 6, 7]. There are numerous processes such as cold isostatic pressing, uniaxial pressing, CVD, hot pressing etc. by which dense ceramic materials can be prepared. Numerous investiga- tions were carried out to develop alumina-chrome system by several researchers applying different methods of preparation altering variable parameters. It has been found that furnace atmosphere of reducing condition and addition of additives (TiO 2 ) accelerates the densification process of alumina-chrome refractory [8–19]. Slip casting is a very useful method of ceramic forming process. Studies on various slip properties of alumina slurries for slip casting and evaluation of various mechanical properties are present in the literature [20–23]. However, information on method of preparation of alumina-chrome refractory by slip casting method and its high temperature corrosion by molten glass is not well reported. In the present paper, we have prepared alumina-chrome product using titania additive by slip casting method and sintering was done in reducing condition. The static corrosion tests were carried out at 1200 8C for 4 h with borosilicate glass and investigation on corrosion of the glass–refractory interface were done by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. 2 Experimental 2.1 Materials preparation The major raw materials used in this study are calcined alumina (Al 2 O 3 ) and chromia (Cr 2 O 3 ). All the materials were obtained from S.D. Fine Chemicals, India and all are of chemical grade with >99% purity. Since Al 2 O 3 and Cr 2 O 3 form complete solid solution over the entire composition range, 1:1 Al 2 O 3 and Cr 2 O 3 is selected and 1 wt% TiO 2 was added as sintering additive [8, 18]. The batch material was attrition milled using a zirconia pot and zirconia grinding media for 4 h in ethanol medium, optimized from our earlier studies [18]. The milled slurry thus obtained was dried in air initially at room temperature followed by 24 h drying 742 DOI: 10.1002/maco.201206813 Materials and Corrosion 2014, 65, No. 7 M. Nath, S. Gupta, H. S. Tripathi Refractories Division, CSIR–Central Glass and Ceramic Research Institute, 196 Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032 (India) E-mail: hstripathi@cgcri.res.in K. Dana Advanced Clay and Traditional Ceramics Division, CSIR–Central Glass and Ceramic Research Institute, 196 Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032 (India) ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com www.matcorr.com