Low temperature synthesis of boron carbide using a polymer precursor powder route

Murray, Paul (2013). Low temperature synthesis of boron carbide using a polymer precursor powder route. University of Birmingham. M.Res.

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Abstract

Boron carbide has a leading role in high performance applications due to its excellent mechanical properties. This work assesses the possibility of using polyvinylalcohol (PVA) and boric acid (H\(_3\)B0\(_3\)) to synthesise boron carbide powder (B\(_4\)C) with a small amount of free carbon. The process steps involve:
• Mixing PVA and H\(_3\)B0\(_3\) in a dehydration condensation reaction to synthesise polyvinylborate (PVBO).
• PVBO is pyrolysed to carbonise the PVA and remove water from the boric acid to leave carbon and boron oxide.
• Pyrolysed sample is heat treated to synthesise boron carbide.

A combination ofFTIR, TGA, XRD, Raman Spectroscopy and SEM has been used to characterise the PVBO, pyrolysed product and final heat treated product. The optimum processing conditions found were to use a composition of 3.7 g PVA arid 1 g H\(_3\)B0\(_3\), and to pyrolyse at 600\(^o\) c for 2 hours at a heating rate of 10\(^o\) c min-\(^1\). The pyrolysed sample wassubsequently heat treated at 1400\(^o\) c for 5 hours at a heating rate of 10\(^o\) c min - \(^1\). This produced (B\(_4\)C) powder with a small amount of residual carbon. The results offer a potential low temperature and low cost alternative to the commercially produced (B\(_4\)C).

Type of Work:

Thesis (Masters by Research > M.Res.)

Award Type:

Masters by Research > M.Res.

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