Microwave synthesis of wollastonite powder from eggshells

Wollastonite powder was synthesized by microwave assisted solid-state reaction in a 2.45 GHz microwave furnace with a maximum power output of 2.4 kW. Bio-solid waste eggshell and SiO₂ were used as starting materials for the synthesis. α-Wollastonite formation started at 800 °C. The single phase was obtained after 10 min heating at 1100 °C. The use of microwave heating lowered the processing temperature and time for wollastonite synthesis.     

B deficiency in TiB2 and B solid solution in TiN in TiN–TiB2 composites prepared by spark plasma sintering

Dense TiN–TiB₂ composites were prepared by spark plasma sintering at 2573 K using TiN and TiB₂ powders. With increasing TiN content from 60 to 90 vol%, the c-axis length of TiB₂ in the TiN–TiB₂ composites decreased from the stoichiometric value (0.3230 nm) to 0.3227 nm because of B deficiency in TiB₂, whereas the a-axis length of TiB₂ was unchanged from the stoichiometric value of 0.3031 nm. The lattice parameter of TiN increased from the stoichiometric value (0.4243 nm) to 0.4250 nm with increasing TiB₂ content from 0 to 60 vol% because of B solid solution in TiN.