Ahlatci H. | Candan E. | Çimenoglu H.

Article | 2004 | Wear257 ( 05.Jun ) , pp.625 - 632

In this study, the effect of Si addition up to 8% Si on the abrasive wear and mechanical properties of Al-Si/60 vol.% SiC composites produced by pressure infiltration technique has been investigated. Optimum properties in terms of improved strength and abrasion resistance without significant loss in toughness were obtained when the matrix alloy contained 1% Si. At Si contents higher than 1%, dramatic decrease of toughness was accompanied a reduction in strength and abrasion resistance. © 2004 Elsevier B.V. All rights reserved.

Kaya F. | Bowen P.

Article | 2008 | Materials Science and Engineering A476 ( 01.Feb ) , pp.301 - 307

Fatigue crack growth resistance of metastable ß titanium composite was investigated in different heat treatment conditions. The effects of increased interfacial strength due to peak ageing on the fatigue crack growth, crack opening displacement and fibre bridging were examined and results of fibre fractures monitored by acoustic emission and fibre push back tests were correlated with fatigue crack growth and crack opening behaviour of the composites. It is shown that at maximum applied intensity factor values higher than crack arrest/catastrophic failure transition, peak ageing reduces the fatigue crack growth resistance of composit . . .e due to higher number of fibre fractures which occurs as fibre stress is increased due to increased interfacial shear stress. However, below transition heat treated composite shows better crack growth resistance compared to as-received condition under fixed Kmax,ini values. This favourable effect of increased interfacial strength on the crack growth behaviour is prominent in the composites with smaller initial unbridged defect size. © 2007 Elsevier B.V. All rights reserved Daha fazlası Daha az

Demirkol N. | Kayali E.S. | Yetmez M. | Oktar F.N. | Agathopoulos S.

Conference Object | 2011 | Key Engineering Materials484 , pp.204 - 209

The aim of this study is to produce and to investigate the mechanical and microstructural properties of composite materials made of hydroxyapatite, obtained from natural bovine bone and nano barium strontium titanium oxide (5 and 10 wt%). Compositions were mechanical alloyed and compacted to pellets. The samples were subjected to sintering at different temperatures between 1000°C and 1300°C. Compression strength, Vickers microhardness as well as density were measured. SEM and X-ray diffraction studies were also conducted. With increasing sintering temperature, microhardness, compression strength and density of composites increased. . . .With increasing addition of nano barium strontium titanium oxide (BST) to bovine hydroxyapatite (BHA), microhardness values of composites decreased at all sintering temperatures, but compression strength and density values of composites showed different tendency. Compression strengths of BHA-composites at low sintering temperatures were nearly the same, but their compression strengths at high sintering temperatures decreased with increasing nano BST addition. The best mechanical properties were obtained at 1300°C sintering temperature with BHA-5wt% nano BST. Microhardness and compression strengths values of these nano-oxide composites are generally higher than that BHA-composites produced by traditional methods. Adding of nano-oxides to BHA could be a valuable method to produce rigid and high load carrying ability when compared with BHA-composites produced by conventional methods. Nano-HA and nano-oxides composites could be even better. Those nano-nano studies are still in progress. © (2011) Trans Tech Publications, Switzerland Daha fazlası Daha az

Simsek I.N.G. | Nistal A. | García E. | Pérez-Coll D. | Miranzo P. | Osendi M.I.

Article | 2017 | Journal of the European Ceramic Society37 ( 12 ) , pp.3721 - 3729

The thermal conductivity (?) of AlN (2.9 wt.% of Y2O3) is studied as a function of the addition of multilayer graphene (from 0 to 10 vol.%). The ? values of these composites, fabricated by spark plasma sintering (SPS), are independently analyzed for the two characteristic directions defined by the GNPs orientation within the ceramic matrix; that is to say, perpendicular and parallel to the SPS pressing axis. Conversely to other ceramic/graphene systems, AlN composites experience a reduction of ? with the graphene addition for both orientations; actually the decrease of ? for the in-plane graphene orientation results rather unusual. . . .This behavior is conveniently reproduced when an interface thermal resistance is introduced in effective media thermal conductivity models. Also remarkable is the change in the electrical properties of AlN becoming an electrical conductor (200 S m-1) for graphene contents above 5 vol.%. © 2016 Elsevier Lt Daha fazlası Daha az

Gunduz O. | Yetmez M. | Ekren N. | Kilic O. | Ben-Nissan B. | Oktar F.N.

Conference Object | 2018 | Materials Science Forum923 MSF , pp.89 - 92

Nowadays hydroxyapatite (HA) bioceramics are very important because increasing traffic accidents and ageing of the population. They can be produced from synthetic or natural sources with different production methods. The biggest negative issue of HA is being very brittle and unstable under pressure. Various materials are added for restoring these weaknesses, but there is not so much studies adding nano-ingredients for restoring the mechanical properties of HA. In this study, 5-10% nano-yittria-oxide is added to bovine derived HA (BHA) and to commercial synthetic (CSHA) as a control group. Physical and mechanical properties are exami . . .ned. Results show that adding of nano-ingredients are really helping to mechanical properties of HA. © 2018 Trans Tech Publications, Switzerland Daha fazlası Daha az

Sen F. | Madakbas S. | Bastürk E. | Kahraman M.V.

Article | 2017 | Polymer (Korea)41 ( 6 ) , pp.1019 - 1026

The aim of this study was to improve thermal stability, mechanical and surface properties of thermoplastic polyurethane (TPU) with the addition of colemanite. The TPU/colemanite composites having various ratios of TPU and colemanite were prepared. The chemical structure of the prepared composites was investigated by Fourier transform infrared spectroscopy (FTIR). Thermal properties of the samples were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Mechanical properties of the samples were characterized with stress-strain test. Hydrophobicity of the samples was determined by the contact ang . . .le measurements. Moreover, the surface morphology of the samples was investigated by a scanning electron microscopy-energy dispersive spectrometer mapping (SEM-EDS). Finally, the obtained results prove that the prepared composites have good thermal, mechanical and surface properties and that they can be used in many applications such as the electronic devices, materials engineering and other emergent Daha fazlası Daha az

Madakbaş S. | Türk Z. | Şen F. | Kahraman M.V.

Article | 2017 | Journal of Inorganic and Organometallic Polymers and Materials27 ( 1 ) , pp.31 - 36

The purpose of this study is polyethylene terephthalate (PET) and modified organo-nanoclay with different masses and to contribute to the different areas of use and literature by examining these nanocomposites physical, chemical and thermal features. In this study, nanocomposite films, which work in PET that is a type of polymeric material, and work into modified organo-nanoclays with different percentages, obtained with the method called as in situ polymerization. The chemical structures of nanocomposites prepared were investigated by fourier transform infrared spectroscopy. The surface morphologies of this nanocomposites were exam . . .ined by scanning electron microscope. Their thermal properties were analyzed by differential scanning calorimetry and thermogravimetric analysis. According to the results obtained, the thermal stabilities of modified nanoclay composites got better than PET. Besides, while the percent of clay in the doped PET was rising, its fragility increased. At the same time, high mass of clay formed when the percent of contribution developed. Thus, the surface interaction of polymer–clay decreased, because the composed aggregations prevented the polymer matrix from going into the layer of clay. © 2016, Springer Science+Business Media New York Daha fazlası Daha az