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

PENGARUH WAKTU DRY MECHANICAL MILLING DAN HEAT
TREATMENT TERHADAP MIKROSTRUKTUR, DENSITAS DAN SIFAT
MAGNET DARI NdFeB

ABSTRAK

Telah dilakukan proses penghalusan serpihan NdFeB dengan menggunakan
conventional ball mill dengan menggunakan metode dry milling dalam atmosfir
gas inert dengan menggunakan gas Nitrogen (N2) saat proses milling berlangsung.
Bahan yang digunakan adalah serpihan NdFeB. Waktu milling yang menjadi
parameter penelitian divariasikan selama 8 jam, 16 jam, 24 jam dan 48 jam.
Kemudian serbuk NdFeB diukur diameter partikel serbuk dengan PSA, analisis
struktur kristal dengan XRD, pengamatan mikrostruktur dengan SEM-EDX dan
kurva histeresis dengan VSM. Untuk pengujian densitas, sifat magnetik (fluks
density) dan kurva B-H dengan Permagraph dilakukan pada sampel berbentuk
pelet. Sampel dalam bentuk serpihan yang telah dimilling dengan berbagai variasi
waktu milling, dicetak dengan gaya 7 tonf selama 2 menit, dan dengan
ditambahkan bahan perekat celuna sebanyak 3 wt%, hingga membentuk pelet
dengan diameter ±1,6 cm. Selanjutnya sampel pelet di heat treatment selama 1
jam pada suhu 110ᵒC , 150ᵒC dan 170ᵒC. Sampel pelet kemudian dicoating
dengan sirlak. Kemudian, sampel pelet diukur densitasnya dengan menggunakan

jangka sorong. Sampel pelet yang telah dilakukan heat treatment, dimagnetisasi
dengan impulse magnetizer pada tegangan 1500V DC. Sampel pelet yang telah
dimagnetisasi diukur fluks density menggunakan Gaussmeter. Dari nilai densitas
fluks magnet sampel, diperoleh sampel terbaik yaitu sampel hasil milling selama
48 jam pada suhu heat treatment 170ᵒC dan diperoleh fluks magnet sebesar 485,8
Gauss. Densitas tertinggi sebesar 5,740 gr/cm3 dan koersivitas pelet NdFeB yaitu
1,171 kOe dan BHmaks sebesar 0,62 MGOe.
Kata kunci : NdFeB, heat treatment , dry milling , ball mill , gas inert

Universitas Sumatera Utara

EFFECT OF DRY MECHANICAL MILLING TIME AND HEAT
TREATMENT ON MICROSTRUCTURE, DENSITY AND MAGNET
PROPERTIES OF 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.

Keywords : NdFeB, heat treatment , dry milling , ball mill , inert gas

Universitas Sumatera Utara