Improvements in the MgB2 ceramics formation by using a dry mechanical milling method

Abstract

The development of the MgB2 manufacturing process to increase current density is an important issue to study. In this work, the MgB2 ceramics were manufactured by using the solid-state technique. To study the influence of dry milling on the formation of the MgB2 ceramics and grain size, variations in ball to powder weight ratio (BPR) and sintering temperature were used as control parameters. Magnesium and boron powder with stoichiometric ratio 2:1 was weighed and milled for 2 h. The milled powder was compacted and sintered at 1023 K and 1123 K for 2 h. By XRD and SEM analysis, we confirmed that the BPR ratio increased magnesium reactivity in MgB2 ceramics formation and refined the grain size. The MgB2 phase of 88.21% was obtained in the sample sintered at temperature of 1123 K and BPR=2:1. To determine the critical temperature of MgB2, we select the sample with the smallest impurities phase to measure its electrical property. The critical onset temperature (Tc-onset) for the selected sample is 40.56 K (?Tc = 0.4 K).