The thermal behavior of alumina borate whisker with Bi(OH)3–Sn(OH)4 coatings

An alumina borate whisker with Bi(OH)3–Sn(OH)4 was prepared using a chemical method. The thermal decomposition of Bi(OH)3 and the evolution process of Bi2O3 (decomposition products of Bi(OH)3) as well as the thermal stability of the whiskers with coatings were described in detail. It was found that the whiskers are an important factor for accelerating the crystallization and decomposition of Bi(OH)3. The presence of the whiskers reduced the transition temperature of α-γ Bi2O3, but enhanced the transition temperature of γ-δ Bi2O3. The reaction between the whiskers and Bi2O3 is responsible for the phenomena. In addition, it can be found that the presence of whisker does not change the thermal process of mixed Bi(OH)3
• Sn(OH)4.

The TG-DSC curves of the whiskers with Bi(OH)3 and Bi(OH)3·Sn(OH)4 were presented, respectively. For the former, the thermal decomposition process consists of the decomposition of Bi(OH)3 and the phase transformation of Bi2O3. For the latter, the thermal decomposition process consists of the decomposition of Bi(OH)3·Sn(OH)4 and the reaction between Bi2O3 and SnO2.Figure optionsDownload as PowerPoint slideHighlights
► Thermal decomposition behavior of Bi(OH)3–Sn(OH)4 with and without whisker is similar.
► Presence of whisker accelerates the crystallization and decomposition of Bi(OH)3.
► The presence of whisker changes the transition temperature of Bi2O3.
► When the heating temperature is above 680 °C, whisker and Bi2O3 can react.
► When the heating temperature is above 605 °C, Bi2O3 and SnO2 can react.