Abstract—This study investigated bulk crystallization at pre-set temperatures of B2O 3-SiO2-Al2O 3-BaO-MgO glass system. Heat treatment at pre-set temperature was carried out between 900 and 1200 ° C on clear glasses to form non-transparent glass-ceramics. Structure of glasses were studied by Fourier transform infrared spectroscopy, phase evolution in the bulk crystallized samples was studied by x-ray diffraction, microstructures were observed by scanning electron microscope and micro-hardness was measured by Vickers method. Aluminum borate whiskers/rods were in the nano to micro sized regime and dispersed randomly within the remaining glass matrix. Whiskers had different sizes and morphologies depending on the heat treatment temperature. Increasing heat treatment temperature led to an increase in crystal size, length and the formation of hollow tubes. The surface hardness decreased when the morphology changed from fine rods into hollow tubes. The synthesized glass-ceramics in this study can be applied as machinable materials in various applications because their microstructures can resist microcracking.

Index Terms—Glass, crystallization, microstructure, whiskers, hardness.

P. Sooksaen is with the Department of Materials Science and Engineering, Faculty of Engineering and Industrial Technology, Silpakorn University. Nakhon Pathom 73000 Thailand and Center of Excellence for Petroleum, Petrochemicals and Advanced Materials, Chulalongkorn University, Bangkok 10330 Thailand (e-mail: pat@su.ac.th).

Cite: Pat Sooksaen, "Structure and Crystallization of Borate-Based Glasses for Machinable Material Applications," International Journal of Applied Physics and Mathematics  vol. 2, no. 2, pp. 089-092, 2012.