ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 64, (4) 434 - 446 (2020)


USE OF PARTIALLY HYDROLYZED PVA FOR BORON CARBIDE SYNTHESIS FROM POLYMERIC PRECURSOR
 
Karaahmet Oguz, Cicek Bugra
 
Yildiz Technical University, Department of Metallurgical and Materials Engineering, 34210, Esenler, Istanbul, Turkey.

Keywords: Industrial raw materials, Sol-gel, pH, Composition ratio, Single-source reactant, Low temperature, Boron Carbide (B₄C) , Hydrolyzed PVA
 

Boron carbide (B₄C) synthesis from a polymeric precursor is an alternative to a traditional carbothermal reduction, promising low energy consumption and production costs, particularly for a polymeric precursor such as polyvinyl borate (PVBO). The sol-gel technique is preferred in the production of polymeric precursors owing to its convenience in producing single-source reactants for synthesizing B₄C at low temperatures (˂ 1800 °C). The sol-gel parameters, such as the composition, viscosity, and pH, affect the formation of the polymeric precursor. In this study, industrial-grade partially hydrolyzed PVA and technical-grade boric acid (H₃BO₃) are used to produce PVBO. We aim to specify the viscosity and pH values for different ratios of PVA:H₃BO3₃. A sample with a weight ratio of PVA:H3BO3 of 1:1 (PHD101) is determined to have the optimum process parameters. Calcination is performed between 500 °C and 700 °C for 1-3 h to produce a single-source reactant, which consists of boron oxide (B₂O₃) and carbon. It was observed that B₂O₃ was distributed on the nano-scale level in the carbon matrix. The reactant is heat-treated at 1400 °C for 5 h and crystalline, polyhedral, and irregular B₄C particles are synthesized at low temperatures from industrial grade raw materials.


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doi: 10.13168/cs.2020.0031
 
 
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