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Effect of process variables on the synthesis of MgB2 by high energy ball mill

Kurama H., Erkus S., Gasan H.

Physicochemical Problems of Mineral Processing

2017

Vol. 53, iss. 2

969--982

Discovery of superconductivity of MgB2 with a critical temperature of -234 °C has offered the promise of important large-scale applications. Except for the other featured synthesis methods, mechanical activation, performed by high-energy ball mills to synthesis of bulk form of MgB2 or as a first step of wire and thin film production has considered as an effective alternative production route in recent years. The aim of the present study was to determine the effect of process variables such as the ball-to-powder weight ratio (BPR), size of ball, milling time, annealing temperature and contribution of process control agent (toluene) on the product size, morphology and conversion level of precursor powders to MgB2 after subsequent heat treatment. Although, the test results revealed relatively lower weight percent of MgB2 phase formation compared with the literature, the reduced milling time, BPR and sinterability of pre-alloyed powder to MgB2 at lowered temperature (630 °C) enhanced the applicability of mechanical alloying with SPEX mill.

An investigation on fatigue life of borided AISI 1010 steel

Celik O. N., Gasan H., Ulutan M., Saygin M.

Journal of Achievements in Materials and Manufacturing Engineering

2009

Vol. 32, nr 1

13-17

Purpose: This study aims to investigate the fatigue life of box borided AISI 1010 steel materials. Design/methodology/approach: Fatigue specimens firstly have been prepared according to ASTM E466-96 standard and normalized. Then their surfaces have been cleaned by polishing. Boriding heat treatment has been applied in solid media with the help of Ekabor2 powder. Specimens have been borided at 1173-1223-1273 and 1323 K temperatures for 2-4 and 6 hours respectively. Fatigue tests have been made in rotating-bend test device. Separate S-N diagram has been formed for each boriding condition and then their results were compared with the results of the specimens on which any heat treatment has not been made. Findings: As a result it has been seen that boriding has no positive effect on fatigue life of AISI 1010 steel materials. And also it has been determined that fatigue life of the materials on which boriding heat treatment applied, decreases in between 14 %-55 %. Research limitations/implications: It can be noted that the reasons of short fatigue life determination are the boride layer’s much higher hardness than the substrate material’s, and the micro cracks existed between boride phases formed onto the surface. Originality/value: The investigations on fatigue life of borided AISI 1010 steel were made.