Abstract
ABSTRACTDense aluminum borate (Al18B4O33) materials were processed by simple milling-sintering of aluminum borate powders obtained by reacting calcined alumina and fine boric acid at temperatures of around 600–800ºC. The effect of milling on the grain size and sintering behavior of the aluminum borate powders was also determined. Sintering began at around 1000°C and was limited by the thermal decomposition (T > 1300 °C) of the borate in to alumina and boron oxide, which volatilize at this temperature. Sub-angular and medium spherical sintered grain microstructures were developed. A hardness of 6 GPa and bulk density below 2.5 g/cm3 were achieved. The results are accomplished encouraging the structural applications of borate materials.
Highlights
The formation of boron-aluminates (BA: Al18B4O33) from alumina and boron oxide occurs at intermediate temperatures, with respected to other alumina binary systems
In a recent article [27], we presented a systematic study of the formation of aluminum borate from boric acid and calcined alumina (D50: 2.5 μm)
The starting powder and milled powder were analyzed by X-ray diffraction (XRD PW 3710, Philips, The Netherlands, with Kα: Cu as incident radiation and Ni filter) in the range 2θ between 10 and 70° in order to evaluate the effect of milling time on crystallinity
Summary
The formation of boron-aluminates (BA: Al18B4O33) from alumina and boron oxide occurs at intermediate temperatures (approx 600–800 °C), with respected to other alumina binary systems. These materials present high refractoriness up to 1300oC, accompanied by chemical inertness in some environments [1]. The catalytic properties of these phases for some technological reactions is remarkable [2,3,4]. The utilization of aluminum borate needles or whiskers for reinforcement of aluminum and aluminum-based alloys is the principal application of these phases [9]. Vitroceramics with aluminum borates as the crystalline phase were studied and presented attractive technological properties [11]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
