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Performance of Mn/Bi2O3 Pyrotechnic Time Delay Compositions

100%

Tichapondwa S. M. , Guo S. , Roux W. E.

Central European Journal of Energetic Materials

2021

tom Vol. 18, no. 1

46--62

Chemical time delay detonators are used widely in mine blasting applications. In order to achieve effective blasting, detonations must follow a precisely controlled timing sequence in a specified firing pattern. Silicon fuel-based pyrotechnic compositions are widely used in mining detonators and are well studied. However, some of these formulations are deemed to be problematic, as they contain heavy metals which are bio-accumulative and toxic to the environment. Therefore, there is need to explore alternative formulations which are suitable for these applications. Manganese-fueled systems are attractive due to their metallic properties and several oxidation states of the manganese fuel. This study focused on characterizing the burn properties of Mn/Bi2O3 compositions for slow to intermediate time delay applications. The compositions supported combustion in the 25 to 55 wt.% Mn range in an inert helium atmosphere. Burn rates between 2.5 and 11.2 mm·s–1 were recorded in open burn tests, whilst closed burn tests in glass tubes resulted in burn rates of 6.3 to 11.2 mm·s–1. Both X-ray diffraction analysis of the reaction products and thermodynamic simulations confirmed that MnO and Bi are the main reaction products, with unreacted Mn and Bi2O3 also being detected. This suggests that the dominant reaction for this composition is a simple thermite-type reaction.

Antimicrobial activity, viability, and physicochemical properties of an MTA-type cement with different concentrations of bismuth trioxide

86%

Martínez-Hernández M. , Manzo-García D. , Ramírez-Ortega J. P. , Arreguín-Cano J. A. , Chávez-Cortéz E. G. , Arenas-Alatorre J. Á. , Rodríguez-Chávez J. A. , Flores-Ledesma A.

Materials Science Poland

2023

tom Vol. 41, No. 2

339--353

In medicine, bismuth is used as an antimicrobial agent. In dentistry, it is used primarily to increase radiopacity in some endodontic materials. The objective is to evaluate the antimicrobial activity, cell viability, pH, solubility, film thickness, and setting time of a mineral trioxide aggregated (MTA)-types of cement with different concentrations of bismuth trioxide. Three experimental MTA-types of cement with a bismuth trioxide (Bi2O3) concentration of 15 wt%, 20 wt%, and 25 wt% were used. The antimicrobial activity test was conducted on Streptococcus mutans and Porphyromonas gingivalis strains. Cell viability was measured by the quantitative colorimetric assay using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide) assay on a mouse fibroblast cell line (L929). Solubility, film thickness, and setting time were performed according to ISO 6876. The lowest Bi2O3 concentrations showed the best antimicrobial activity and cell viability, pH, solubility, setting time, and film thickness did not show statistically significant differences between the different Bi2O3 concentrations tested.