Karabudak, Filiz

In this study, an epoxy layer was formed by the immersion process, on the oxide layer grown by the micro-arc oxidation (MAO) treatment of the AZ91 magnesium alloy, using the thin film sealing technology, and its effect on fatigue and tensile stress under high cycle conditions was investigated. The microstructures of the AZ91 base material, MAO/AZ91 and MAO-epoxy/AZ91 samples, which were subjected to high-cycle fatigue tests and uniaxial static tensile tests, were assessed through the scanning electron microscope (SEM), X-ray diffraction (XRD) mechanical tests, and fatigue and tensile tests. As a result, the MAO-epoxy duplex coating, which has a homogeneous and compact structure, was observed to improve the fatigue limit value/life, yield strength, ultimate tensile strength, and percentage elongation values of the base material significantly.

Çelik, I.; Karakan, M.

Commercial pure titanium (CP-Ti) is used in many engineering fields because of its superior properties such as excellent corrosion resistance, high strength/weight ratio, and biocompatibility. However, it is not available at the desired rate, since the CP-Ti has poor wear resistance. For this reason, many surface treatments have been applied to improve the poor tribological properties of the CP-Ti. In this study, duplex surface treatments, which are the combination of treatments of electroless Ni-B coating and plasma nitriding, were applied on the surfaces of the CP-Ti. Structural properties of the different surfaces of the treated materials were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Microhardness measurements were made for the determination of mechanical properties and the pin-on-disk wear tests were made to determine the tribological properties. It was observed that poor wear resistance of the CP-Ti was improved with duplex surface treatments. The results showed that surface hardness, friction coefficient, and surface roughness of coated samples were better than of uncoated CP-Ti.

Budak, S.; Kaplan, M.

In this study, four different kinds of marble cutting matrices with a base composition of Fe-Cu-Sn and with variable amounts of Co powder were produced. For compaction, hot sintering process was carried out at 850°C under 35 MPa for 4 min. The mechanical and microstructural properties of the matrix materials were determined using SEM with EDS, three-point bending test, density and hardness measurement techniques. The addition of Co powders to the matrix and the subsequent hot sintering process affected the mechanical and microstructural properties of the cutting tool, such as hardness, total elongation, % porosity and phase distribution.