Development and characterisation of a carbon fibre reinforced MAX phase composite material.

Nel, Jan Heimriks (2017-12)

Thesis (MEng)--Stellenbosch University, 2017.

Thesis

ENGLISH ABSTRACT: A carbon fibre reinforced MAX phase ceramic matrix composite (CMC) was produced in prepreg form and sintered using spark plasma sintering (SPS). MAX phase ceramics is a group of ternary ceramics exhibiting a combination of advantageous properties of both metals and ceramics. The CMC prepreg was designed with a carbon fibre weave acting as reinforcement and a MAX phase (Ti2AlC) acting as the matrix. Polymethyl methacrylate (PMMA) was used to coat the fibres and Ti2AlC powder combination to achieve a flexible and robust prepreg. Ti2AlC powder was prepared by attrition milling in a liquid medium. The particle size distribution was measured using dynamic light scattering (DLS) and scanning electron microscopy (SEM). The mean particle size was reduced from 16 cm to 275 nm, allowing infiltration of the powder into a fibre weave. The effect of the attrition milling on the elemental composition of the powder was evaluated using energy dispersive spectroscopy (EDS) and powder X-ray diffraction (PXRD). Electrophoretic deposition (EPD), vacuum infiltration, and pressure infiltration were evaluated for ceramic infiltration into a carbon fibre weave. The ceramic infiltration was investigated by examining polished cross-sections using optical microscopy. Prepreg layers were combined and thermal debinding was performed at 400 °C to remove the PMMA coating. The CMC was sintered using SPS at 20 MPa and 1400 °C to create a 30 mm CMC disc. The sintered CMC had a density of 2.04 g/cm3 and open porosity of 16 %. The microstructure of the CMC was evaluated using optical microscopy, SEM, and X-ray computed tomography (CT). The discs were fractured using the ball on three balls (B3B) test method to determine the strength and mechanical response. EDS and SEM analysis was employed to evaluate diffusion between carbon fibres and Ti2AlC matrix. Aluminium diffused from the matrix into the fibres, resulting in the formation of Al4C3 in the carbon fibre and TiC in the matrix surrounding the fibre.

AFRIKAANSE OPSOMMING: 'n Koolstof-versterkte MAX-fase keramieksamestelling was in 'prepreg' vorm gelewer en gesinter deur gebruik te maak van vonk plamsa-sintering (VPS). MAX-fase keramieke is n drieledige groep keramieke wat n kombinasie van bevorderlike eienskappe van beide metale en keramieke bevat. Die keramieksamestelling is ontwerp met n koolstofveselweefstof wat as n versterker en n MAX-fase (Ti2AlC) wat as n matriks optree. 'n Bindstof (PMMA) was gebruik om die vesels en Ti2AlC-poeier kombinasie te bedek om n buigsame en sterk 'prepreg' te lewer. Ti2AlC-poeier is deur middel van afslytingsmaling in n vloeibare medium voorberei. Die partikelgrootte is deur dinamiese straalstrooiing en skanderings-elektronmikroskopie (SEM) gemeet. Die mediaan partikelgrootte is van 16 µmm na 275 nm verminder wat toelaat dat die poeier die weefstof in ltreer. Die uitwerking van die afslytingsmaling op die poeier se elementale samestelling is deur middel van energie-verstrooings-spektroskopie (EVS) en poeier X-straaldi raksie bepaal. Elektroforetiese neerslagvorming , vakuumin ltrasie en drukinfiltrasie is gevalueer vir keramiek-in ltrasie in n koolstofweefstof. Die keramiekinfiltrasie is ook ondersoek deur n gepoleerde deursnit deur middel van optiese mikroskopie waar te neem. 'Prepreg'-lae is gekombineer en termiese ontbinding het teen 400 °C plaasgevind om die PMMA deklaag te verwyder. Die keramiek-samestelling is deur middel van VPS teen 20 MPa en 1400 °C gesinter om 30 mm keramiek-samestallingskywe te vorm. Die gesinterde keramiek-samestelling het n digtheid van 2.04 g/cm3 en n oopporeusheid van 16 % gehad. Die mikrostruktuur van die keramiek-samestelling is deur optiese mikroskopie, SEM en X-straal-saamgestelde tomografie. Die skywe is deur middel van die bal op drie balle (B3B) toetsmetode gebreek om die sterkte en die meganiese vermo daarvan te toets. EVS en SEM-analise is ingespan om die diffusie tussen die koolstofvesels en die Ti2AlC-matriks te evalueer. Aluminium het vanaf die matriks na die vesels gediffundeer en gelei tot die vorming van Al4C3 in die koolstofvesels en TiC in die matriks rondom die vesels.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/102884
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