Thesis
Synthesis and evaluation of organic/inorganic hybrid materials for high temperature applications
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2024
- Thesis identifier
- T16857
- Person Identifier (Local)
- 201793904
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Organic-inorganic hybrid materials are becoming increasingly used in industry for providing usefulproperties, including high mechanical strength and thermal resistivity. As part of this thesis, the useof these materials in joining silicon carbide (SiC) rods for use in heating elements was investigated.A phenol-formaldehyde (PF) based resin is used in an organic adhesive-based system for joining SiCheating elements. The thermal profile determined that the thermal stability was low, the variationbetween resin chemistry was high and porosity was a major issue for the resistance and strength ofthe weld. Due to this a replacement system was identified.The pre-ceramic polymer Allylhydridopolycarbosilane (AHPCS) was identified as a replacementadhesive. Using thermal volatilisation analysis accompanied with solid-state nuclear magneticresonance, Fourier-Transform infrared spectroscopy, mass spectrometry, differential scanningcalorimetry and thermogravimetric analysis the thermal profile was identified. Three thermalprocesses were observed between 160-670 °C. AHPCS cross-links through the allyl group andundergoes carbon-silicon rearrangement, with volatilisation of oligomers, chain fragments andcompounds such as methane, ethane, methanol, propane, propene. The major volatile released ishydrogen from dehydrocoupling of Si-H and C-Hbonds which leads to radical recombination of siliconand carbon, forming the SiC network which recrystallises to β-SiC by 1100 °C. Dicumyl peroxide at 1 %w/w was used as the thermal initiator which provided AHPCS with the highest final ceramic yield. TVAanalysis showed differences in the thermal profile with lower cross-linking temperature, reducedvolatilisation and higher Si-C recombination compared to unadulterated AHPCS. The post-fired flexuralstrength, resistance and porosity were improved in the AHPCS based formulations with only greenstrength being higher in the PF resin. This, along with both the safety and the consistency betweenadhesive chemistry, showed that AHPCS with dicumyl peroxide was a successful replacement for thePF resin in joining SiC heating elements.
- Advisor / supervisor
- Liggat, John
- Resource Type
- DOI
- Embargo Note
Relações
Itens
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File | 2024-05-07 | Embargo |