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    Dry sliding wear behavior of low carbon dual phase powder metallurgy steels
    (Elsevier Sci Ltd, 2007) Tekeli, S.; Gural, A.; Ozyurek, D.
    Dry sliding wear behavior of Fe + 0.3% graphite powder metallurgy processed (PM) steels was investigated at constant sliding speed, load and distance. For this purpose, atomized iron powder was mixed with 0.3% graphite powder and sintered at 1200 degrees C for 30 min under Argon gas atmosphere. The sintered PM specimens were intercritically annealed at different temperatures (728 and 760 degrees C) and then water-quenched. After sintering, a typical ferrite + pearlite microstructure was obtained. In the microstructure of the intercritically annealed PM specimens, a ferrite + martensite microstructure was produced. After wear tests, it was seen that the wear rate of the intercritically annealed specimens was very low in comparison to as-sintered specimen. The specimen intercritically annealed at 728 degrees C showed the lowest wear rate, despite its lower martensite volume fraction. (c) 2006 Elsevier Ltd. All rights reserved.
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    EFFECT OF Al2O3 AMOUNT ON MICROSTRUCTURE AND WEAR PROPERTIES OF Al-Al2O3 METAL MATRIX COMPOSITES PREPARED USING MECHANICAL ALLOYING METHOD
    (Springer, 2010) Ozyurek, D.; Tekeli, S.; Gural, A.; Meyveci, A.; Guru, M.
    This paper reports the outcome of an investigation into the effect of Al2O3 content on the microstructure and wear properties of Al-Al2O3 metal matrix composites. The Al-Al2O3 composites are prepared by a mechanical alloying method using Al2O3 powders up to 20 vol.% as reinforcement. Alloying is performed in a vibration mill using a ball-to-powder ratio 10: 1 and a milling time varying from 30 to 100 min at a rate of 710 Hz. The prepared compositions are cold pressed at 630 MPa with a single action and sintered at 560 degrees C for 30 min under Ar gas atmosphere. The experimental results show that the reinforcing phase Al2O3 is homogeneously dispersed in the Al matrix and the interface between Al matrix and Al2O3 is well formed. Wear tests are carried out under dry sliding conditions using a pin-on-disk testing machine at three different loads of 10, 25, and 50 N and at a sliding speed of 2.08 m/sec. Total sliding distances are selected as 400, 800, 1200, and 1600 m. It is seen that the wear rate decreases with increasing Al2O3 content and sliding distance at a sliding speed of 2.08 m/sec.
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    Microstructure and dry sliding wear properties of 3Si-2Ni and 3Si-2Mn powder metallurgy steels with different graphite content
    (Sage Publications Ltd, 2011) Tekeli, S.; Gural, A.; Ozyurek, D.
    In this study, plain iron powder (ASC.100.29) was mixed with 0.35-1.1 % graphite + 3 % Si + 2 % Ni and 0.35-1.1 % graphite + 3 % Si + 2 % Mn powders. While coarse pearlitic structure with homogeneous distribution of Mn was obtained in Mn-added specimens, Ni-rich austenitic areas with divorced pearlite structure were observed in Ni-added specimens. Wear tests were carried out at a load of 50 N. The experimental results showed that the highest wear resistance was obtained in the Ni-added specimen. While subsurface brittle cracking caused more wear in the Mn-added specimens, the wear occured by plastic deformation of surface Ni-added specimens.