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    Effect of T7 heat treatment on the dry sliding friction and wear properties of the SiC-reinforced AA 2014 aluminium matrix composites produced by vacuum infiltration
    (Sage Publications Ltd, 2014) Aksoz, Sinan; Bican, Osman; Calin, Recep; Bostan, Bulent
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    Effects Of Sintering, Ageing And Cryogenic Treatments On Structural And Mechanical Properties Of Aa2014-B4c Composite
    (Gazi Univ, Fac Engineering Architecture, 2013) Aksoz, Sinan; Ozdemir, A. Tamer; Çalın, Recep; Altinok, Zemzem; Bostan, Bulent
    In this study, powders of gas atomized AA2014 and solid B4C were mixed and then used in an infiltration system. To attain particulate reinforced aluminum composites, fine particles of B4C were added in right proportions of 10% and 20% respectively. Micro structures of AA2014-B4C composite were then analyzed systematically, where at first hardness measurement were applied after liquid phase sintering, ageing and cryogenic cooling. Samples were then analyzed with scanning electron microscopy (SEM) techniques to determine the effect of several heat treatment steps on the microstructure. It was found that hardness values particularly obtained right after cryogenic cooling treatment were considerably higher than that of sintering and ageing treatments. These results show that, application of cryogenics may play an effective role in the behaviour of age-hardenable alloys.
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    Investigation of the Effect of Sintering Temperatures on the Production of Porous NiTi Alloy by Loosen Sintering Method
    (Kırıkkale Üniversitesi, 2023) Tanış, Naci Arda; Bostan, Bulent
    This article aims to produce NiTi shape memory alloys, which show superelasticity and shape memory effect, as well as good biocompatibility and corrosion properties, in open and porous sizes ranging from 100-500 ?m, which are required for use as implants. This structure of pores is necessary to allow tissue growth and fluid flow inside the implants. Many powder metallurgy methods have been used in producing porous NiTi shape memory alloys. However, the packaging pressure used in these methods has not successfully created the desired pore distribution, shape, and size. The methods by which it can be produced are costly in terms of cost. In the study, production was carried out by sintering the powder mixture poured into molds without pressure with the help of binder polymers. This sintering process was carried out in an argon atmosphere for 1 hour at temperatures 1050, 1125, and 1200 °C. The study shows that pressureless loosen sintering can produce porous NiTi alloys, which is the more straightforward method. The pore distribution and proportions were examined. Homogeneous distribution and pores in desired sizes are created. It has also been determined that the binder polymer has a space-retaining effect. It was determined at which temperature the alloy sintered at different temperatures contained the desired B2 austenite phase for superelasticity. Austenite start and finish temperatures were determined for the alloy produced at each sintering temperature. As a result of this research, it was determined which phase was denser at which temperature, and the phase transformation temperatures were found. The exact temperature measurements can be calculated by changing the sintering time parameter. In addition, the change in phase transformation temperatures can be measured by heat treatment after sintering. Porous NiTi alloys can be used as dental and medical implants thanks to their excellent biocompatibility and corrosion resistance. This method will decrease production costs, and more people will have access to this material. In general, the mechanism of sintering methods is joining the points in contact with the packaging pressure by necking. In this study, the combination of the grains with the polymer without packaging pressure with the thermal expansion mechanism reveals the originality of the study.