Effect of High‐Energy Ball Milling and Silica Fume Addition inBaCO₃–Al₂O₃. Part I: Formation of Cementing Phases

Abstract

The effects of high-energy ball milling and subsequent calcination on the formation of barium aluminate cementing phases using mixtures of Al 2 O 3 and BaCO 3 were investigated. Silica fume was further added in the raw mixtures to observe its role on the cementing phase formation. Results indicated that the decomposition temperature of BaCO 3 lowered remarkably with the increase in milling time. Barium aluminate cements with grain size in nanometer range were obtained from high-energy ball-milled raw mixtures. X-ray diffraction (XRD) results confirmed several crystalline barium-silicate and barium aluminate phases present. Formation of crystalline BaOÁAl 2 O 3 phase was observed between 1000°C and 1100°C in the raw mixtures, which were obtained in amorphous state after milling for 5 h. This temperature is at least 300°C lower than that used in the traditional solid-state method. Fume SiO 2 additions resulted in BaOÁAl 2 O 3 Á2SiO 2 (celsian) formation which acted as a retarder, provides more workability and mechanical strength.M. Rigaud-contributing editor Manuscript No. 34918.

Role of CaF2on mechanochemically synthesized leucite as dental veneering glass ceramics

“…These prepared materials are suitable for PFM as its CTE value of 14?2610 26 uC 21 is close to standard CTE of nickel-chrome alloy (13?9610 26 uC). 31 3 Variation of crystallite size of MCL and MCL-C with temperature 4 Coefficient of thermal expansion curves of LTF, MCL1000, MCL1100, MCL-C1000 and MCL-C1100 …”

“…These prepared materials are suitable for PFM as its CTE value of 14?2610 26 uC 21 is close to standard CTE of nickel-chrome alloy (13?9610 26 uC). 31 3 Variation of crystallite size of MCL and MCL-C with temperature 4 Coefficient of thermal expansion curves of LTF, MCL1000, MCL1100, MCL-C1000 and MCL-C1100 There is no visible microcrack appearance due to phase transformation of metastable kalsilite to leucite. The particle size distribution of the leucite crystal is in the range of 0?6-1?0 mm.…”

“…This preparation method is simple, economical and also suitable for large scale production of other nanoparticles ceramic system. 25 This process has been successfully utilised to obtain a number of nanomaterials including Al 2 O 3 , 26 ZnO, 27 31 The main idea of the present work is to demonstrate that submicrometre size leucite glass ceramics can be produced at relatively low temperatures using mechanically activated precursors. Two blends in which one containing Al 2 O 3 , SiO 2 and K 2 CO 3 in the stoichiometric ratio of leucite and the other with same stoichiometric ratio with 2 wt-%CaF 2 as additive was prepared.…”