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1
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Microstructure and Hardness Characteristics of Al₂O₃-B₄C Particle-Reinforced Cu Matrix Composites

100%
Öksüz K., Şahin Y.
Acta Physica Polonica A
|
2016
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vol. 129
|
issue 4
650-652
EN
Copper is widely used in industrial applications because of its high electrical and thermal conductivity, easiness of processing and good corrosion resistance. However, copper also has some distinct limitations such as low hardness, low tensile yield strength and poor creep resistance. In this report copper matrix was reinforced with ceramics like Al₂O₃ and B₄C particles using powder metallurgy (PM) method and its microstructure was examined with SEM and EDS. The microstructure has revealed an uniform distribution of particles in the matrix and a good interface bonding between B₄C particles and the matrix. However the dispersion of Al₂O₃ particles, of larger sizes, has led to some porosity and inter-particle contacts in the composites. Therefore, hardness of B₄C particle-reinforced composites is significantly higher than that of Al₂O₃ particle-reinforced composites.
2
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Effect of Yttria on the Phase Formation and Sintering of HA-Al₂O₃ Biocomposites

100%
Öksüz K., Özer A.
Acta Physica Polonica A
|
2017
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vol. 131
|
issue 3
576-579
EN
Hydroxyapatite is very-well known as the main component of hard tissues and, as such, it has attracted much attention by researchers in the recent decades. This study was aimed to present the characterization of Y₂O₃ doped 50 wt.% hydroxyapatite - 50 wt.% Al₂O₃ composite materials fabricated at relatively high temperature of 1600°C. Hydroxyapatite powder was obtained from bovine bones via calcination and ball milling technique. Fine powders ( ≤ 1 μm) of hydroxyapatite/Al₂O₃ were admixed with 0.5 and 1 wt.% Y₂O₃ powders. Powder compacts were sintered at 1600°C for 4 h in air atmosphere. The field emission scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction studies following the relative density measurements were conducted. Moreover, the microhardness was studied as the mechanical property of sintered samples. The effect of increasing Y₂O₃ content on surface morphology, elemental distribution and phase evaluation was investigated in hydroxyapatite/Al₂O₃ biocomposite materials. It was found that by increasing Y₂O₃ content, the relative density increased up to 98.8%, while the hardness increased to 863 HV_{(0.2)}. The main phases, which were found, are Hibonite - CaO(Al₂O₃)₆ and beta-tricalcium phosphate - Ca₃(PO₄)₂, according to X-ray diffraction pattern.
3
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The Effects of Aging on the Hardness and Wear Behaviour of 2124 Al Alloy/B₄C Composites

100%
Öksüz K., Oskay K.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 4
1367-1369
EN
The particulate reinforced aluminum alloy matrix composites are being increasingly used for wear component applications. The influence of matrix aging treatment on wear behavior in a powder metallurgy 2124 Al-B₄C composite was investigated. The aging responses of 2124 Al-B₄C metal matrix composite (MMC) and unreinforced matrix alloy are studied and related to variations in wear resistance properties. The MMC is aged resolution treated. Accelerated aging occurs in both MMC conditions, compared with unreinforced alloy. Wear resistance and hardness were substantially higher in the reinforced alloys. The effects of the percentage of boron carbide addition on the microstructure, hardness and wear tests of the produced material are discussed. The effects of the age hardening process are also considered.
4
Content available remote

Processing and Mechanical Properties of B₄C/Diamond Impregnated Fe/Co MMC

100%
Öksüz K., Şimşir M.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 4
1139-1141
EN
Cobalt is currently used in the production of diamond reinforced metal matrix composites (i.e. stone-cutting tools). Herein, how sintering temperature and matrix composition influences the material properties of diamond reinforced MMCs was explored. The aim of this work is to produce diamond reinforced metal matrix composites based on Fe-Co compositions with and without B₄C are processed by a PM method using a hot pressing technique. The effects of Fe and B₄C additions on the characteristic of diamond impregnated Co matrix composites have been investigated. Samples reinforced with and without B₄C having two different compositions (different Fe/Co ratio) were produced under 25 MPa pressure and sintered at 1000°C temperature. After sintering, hardness tests were carried out and wear tests were performed by pin-on-disc. The results showed that addition of Fe caused slightly decrease in the hardness of the matrix. However, reinforcing with B₄C increased the hardness of the matrix. It is observed that wear resistance of B₄C reinforced Fe-Co metal matrix composite was greater than that of composites without reinforcement. SEM and EDX techniques were used to characterize the composites.
5
Content available remote

Effects of B₂O₃ Addition on the Sintering Behavior of 0-5-10% ZrO₂ Doped BaTiO₃ Based Ceramics

81%
Öksüz K., Şen Ş., Şen U.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 4
1086-1089
EN
In this study, the effect of B₂O₃ addition on the sintering behavior of 0-5-10% ZrO₂ doped barium titanate based microwave dielectric ceramics were investigated. For this purpose, the powder mixtures consisting of BaCO₃, TiO₂ and ZrO₂ were prepared by ball milling technique in alcohol using ZrO₂ balls at 200 cycle/min for 20 h. The prepared powders were calcined at 900°C for 2 h. Produced powders were mixed 0.5% B₂O₃ and 5% PVA and pressed as green body under the pressure of 100 MPa. The disc-shaped die-pressed samples were sintered at 1250°C, 1350°C and 1450°C for 4 h. X-ray diffraction analysis showed that the main phases formed in the sintered samples are BaTiO₃ and Ba(Ti_{1-x}Zr_{x})O₃. The scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to investigate microstructure of the sintered samples. The bulk densities of the sintered samples increased with the addition of B₂O₃ content due to the low number of pores trapped between the grains.
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