2. Materials and methods 2.1 Raw materials and preparation of barium aluminate cements The starting raw materials, aluminum oxide and barium carbonate used in this study, were of AR grade, supplied by Loba Chemie Pvt. Ltd (Mumbai, India). Fumed silica was purchased from Shiva Minerals Pvt. (Rajgangpur, India). For reference purposes, commercially available CA-25 C calcium aluminate cement (Almatis, India) was used. The aluminum oxide and barium carbonate were weighed in a proportion to give an Al2O3:BaO weight ratio of 8:2. Mixtures of aluminum oxide and barium carbonate with and without incorporation of silica fume were prepared in the same manner. Silica fume was also introduced in two proportions, viz. 5 and 10% by weight. The complete coding of the prepared samples is given in Table 1. The mixture containing aluminum oxide and barium carbonate was pulverized in a high-energy planetary ball mill. This planetary ball mill was manufactured by VB Ceramics, Chennai, India. It consists of a cylindrical stainless steel pot of 250 ml, internally coated with tungsten carbide. Tungsten carbide grinding balls with a diameter of 10 mm were used as the hard grinding agent. The grinding media and material weight ratio were maintained at 3:1 and the grinding speed was set at a constant 300 rpm throughout the study. The grinding operation was carried out continuously at room temperature for 1, 3, 5 and 10 h. The introduction of silica fumes was only made into the mixtures after they had been sprayed for 10 hours. They were then mixed thoroughly in an agate mortar for 30 minutes. The milled mixtures were analyzed by differential scanning calorimetry (DSC) to determine their possible reaction temperatures. The NETZSCH DSC 404F3 model was used for this thermal analysis...... middle of article ......rzi, Mechanochemical synthesis of zirconia nanoparticles: formation mechanism and phase transformation, Int. J. Refract. Encounter. Hard. Master. 31 (2012) 21-27.[74]. IS: 4031-4, Method of physical testing for hydraulic cement, Part 4 Determination of consistency of standard cement paste (first revision), pp. 1-6, 1988.[75]. P. Kathirvel, J. Chandrasekaran, D. Manoharan, S. Kumar, Preparation and characterization of alpha alumina nanoparticles by in-flight oxidation of flame synthesis, J. Alloys. Compd. 590 (2014) 341-345.[76]. M. Mohapatra, DM Pattanaik, S. Anand, RP Das, Effect of barium/aluminum ratio on the phases leading to barium aluminates, Ceram. Int. 33 (2007) 531–5.[77]. AR Studart, MDM Innocentini, IR Oliveira, VC Pandolfelli, Reaction of aluminum powder with water in refractory concretes containing cement, J. Eur. Ceram. Soc. 25 (2005) 3135–43.