Processing and characterization of carbon fiber reinforced silicon carbide (C/C-SiC) matrix composites

---

Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Metalurji ve Malzeme Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2015

Öğrenci: SİMGE TÜLBEZ

Danışman: ARCAN FEHMİ DERİCİOĞLU

Özet:

The current study was undertaken to investigate the production and characterization of Carbon Fiber Reinforced Silicon Carbide (C/C-SiC) Matrix Composites. Liquid silicon infiltration (LSI) method was utilized to produce the C/C-SiC composites. Processing of these composites via LSI process composed of three main stages. CFRP production, pyrolysis and liquid silicon infiltration. Each production stage has an important effect on the efficiency of the LSI process, therefore present study investigates the effect of the corresponding parameters on the silicon infiltration process by comparing the properties of the C/C preforms and resulting C/C-SiC composites obtained by various processing conditions. Application of pyrolysis experiments at varying temperatures and TGA of the matrix material revealed that phenolic resin completely converts to turbostratic carbon above the dehydrogenization temperature of the cured phenolic resin. Moreover, increasing pyrolysis temperature results in decreasing density, increasing porosity content and increasing crack opening of the C/C preform which directly affect the efficiency of the LSI process. Taking into consideration of all of the parameters directly affect the efficiency of the LSI process, comparison of density, microstructure and flexural strength of the resulting C/C-SiC composites revealed that pyrolysis should be applied at 1000 °C and following silicon infiltration of the C/C preforms should be conducted at 1650 °C under vacuum. Impregnation of carbon nanotube (CNT) to the C/C preforms as matrix additive enhances the efficiency of liquid silicon infiltration resulting in composite having higher density and strength. Moreover, microcrystalline cellulose, CNT and nano-SiC powders added to the carbon derived from the phenolic resin enhances the SiC formation kinetics.