Pengaruh Waktu Dry Mechanical Milling dan Heat Treatment Terhadap Mikrostruktur, Densitas dan Sifat Magnet dari NdFeB

Abstract

Has been done smoothing process of NdFeB flakes using conventional ball mill by dry milling method within an inert gas atmosphere using Nitrogen gas (N2) while milling process was held. The materials used were NdFeB flakes. Milling time which became the research parameter was varied for 8 hours, 16 hours, 24 hours and 48 hours. Then NdFeB powder particle diameter was measured by PSA, the crystal structure analysis by XRD, microstructure observation by SEM-EDX and the hysteresis curve by VSM. For density test, magnetic properties (flux density) and the BH-curve by Permagraph was done on pellet form samples. Sample in flakes form which has been milled with milling time variety, was pressed with 7 tonf force for 2 minutes and with added adhesive celuna as much as 3 wt% up to become pellets form with a diameter ±1.6 cm. Further the pellet samples were given heat treatment for 1 hour at temperature 110ᵒC, 150ᵒC and 170ᵒC. Pellet samples were then coated with sirlak. Then the pellet samples density was measured using a caliper. Pellet samples that have been done heat treatment, were magnetized with the impulse magnetizer in 1500V DC voltage. Pellet samples that have been magnetized , flux density was measured using a Gaussmeter. From the magnetic flux density sample value, the best sample that obtained was the sample in milling time for 48 hours at heat treatment temperature was 170ᵒC and obtained magnetic flux density at 485.8 Gauss. The highest density at 5.74 g / cm3 and NdFeB pellet coercivity are 1.171 kOe and BHmax 0.62 MGOe.