Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 25Citation - Scopus: 25Characterization Investigations During Mechanical Alloying and Sintering of W-20 Vol% Sic Composites(Elsevier Ltd., 2010) Coşkun, Selim; Öveçoğlu, M. Lütfi; Özkal, Burak; Tanoğlu, MetinThe effect of mechanical alloying and the sintering regime on the microstructural and the physical properties of W-SiC composites were investigated. Powder mixtures of W-20 vol.% SiC were mechanically alloyed (MA'd) using a Spex mill for 3 h, 6 h and 24 h. MA'd powders were characterized by Laser Diffraction Particle Size Analyzer, SEM and XRD investigations. MA'd W-20 vol.% SiC powder composites were sintered under inert Ar and reducing H2 gas conditions at 1680 °C and 1770 °C for 1 h. The microstructural and mechanical characterizations of the sintered samples were carried out by scanning electron microscope (SEM) and X-ray diffraction (XRD) and Vickers Hardness analyses. The addition of SiC remarkably increases the hardness of the composites. Hardness is also increased with decreasing grain size and increasing amount of MA. © 2009 Elsevier B.V. All rights reserved.Article Citation - WoS: 19Citation - Scopus: 23Silicon Oxycarbide-Based Composites Produced From Pyrolysis of Polysiloxanes With Active Ti Filler(Elsevier Ltd., 2006) Akkaş, Hatice Deniz; Öveçoğlu, M. Lütfi; Tanoğlu, MetinPhenyl (PPS) and methyl (PMS) containing polysiloxanes were pyrolyzed at elevated temperatures (900-1500 °C) under argon atmosphere to investigate the phase developments within the polymers. It was found that pyrolysis of the polymers under inert atmosphere up to 1300 °C leads to amorphous silicon oxycarbide (SiOxCy) ceramics. Conversions at higher temperatures results in the transformations into the crystalline β-SiC phases. Ceramic matrix composites (CMCs) were developed based on the active filler controlled pyrolysis (AFCOP) of polysiloxanes with active Ti filler additions. CMC monoliths were prepared with 60-80 wt.% of active Ti particulates blended into polymer precursors. Green bodies of the composites were made by warm pressing under 15 MPa pressure and ceramics were obtained by pyrolysis at elevated temperatures between 900 and 1500 °C under argon atmosphere. The results showed that due to the incorporation of active Ti fillers, formation of crystalline phases such as TiC, TiSi, and TiO occured within the amorphous matrix due to the reactions between the Ti and the polymer decomposition products. The microstructural and mechanical characterization results of the composites are presented within the paper.