MAKING SMALL SPHERES
The mill for the production of small balls, of hard and semi hard material contains as a main part a ring covered with the abrasive material (glued) on the abrasion surface. The ring has the vertical axis. The abrasive surface is made by gluing with glue that softens by heating. The moving of spherical material is made with compressed air, rotating in the grinding space, motion imprinted on the diffuser air. Compressed air comes through the center of the mill through a circuit with minimal aerodynamic resistances. Air pressure: 1 – 2 bar. Ball size: 1 mm. The grinding space has a 7 (horizontal) x 6 (vertical) mm section with an (average) length of 162 mm. The used raw material has cubic shape with a 30 % greater edge than the ball diameter.
Keywords: small spheres, technology, hard and half hard materials
Cuvinte cheie: sfere mici, tehnologie, materiale dure și semidure
MAKING SMALL SPHERES
MORPHOLOGICAL AND STRUCTURAL ASPECTS
OF Fe50Ni50 POWDER MIXTURE SUBJECTED TO
The mechanical alloying experiment was performed inti a planetary
ball mill using elemental Fe and Ni powders mixed together at 50 wt. % ratio.
Powder samples were taken out after 1, 2, 4, 8, 16, 32, 48, and 64 hours of
milling. These samples were subjected to X-ray diffraction, sieving analysis,
and optical microscopy inspection. The results allow us to conclude that Ni
presents a ductile behaviour meanwhile Fe acts as a brittle component which
conducts to the forming of mixed particles of Ni embedding smaller Fe one. The
particle structure is more refined progressive with the milling time. Finally, the
solid solution of Fe in Ni FCC is completely formed at 64 hours of milling.
Keywords: Fe-Ni, alloy mechanical, planetary mill
Cuvinte cheie: Fe-Ni, aliere mecanică, moară planetară
SOLID STATE SOLUBILITY EXTINCTION OF Fe-Ni SISTEM
BY MECHANICAL ALLOYING
Experiments took place in a high energy ball planetary mill, with four
villas. There were used 46 balls having 15 mm diameter to mill 100 g powder
mixtures of Fe80Ni20, Fe70Ni30, Fe60Ni40, Fe50Ni50, Fe40Ni60, Fe30Ni70,
Fe20Ni80 (figures in mass %) in each vial. Milling space of each vial was filled
a half with balls and powder and the balls/powder mass ratio was of 8: 1. There
were taken samples (5 g of mixture powder) at 0, 1, 2, 4, 8, 16, 32, 48, and 64
hours of milling. The appeared identified phases are solid solutions of Fe(VCC)
and Ni(FCC) in the milled mixtures subjected to a minimum 2 hours of milling.
Iron is imposing its crystallizing system between 70 – 100 mass % of Fe and
nickel between 40 – 100 mass % of Ni.
Cuvinte cheie: aliere mecanică, pulberi Fe – Ni, moară planetară
Keywords: mechanical alloying, Fe-Ni powders, planetary mill
The mechanical alloying experiments were performed on a high
energy planetary ball mill. Four vials were used for powder mixtures milling.
The milling charge contains 46 steel balls having 15 mm average diameter and
100 g powder mixture. It corresponds to a charge level of ½ of the vial volume
and represents a 8:1 ball/powder ratio. The powder mixtures: Fe60Ni40, Fe50Ni50,
Fe40Ni60, were milled for 1, 2, 4, 8, 16, 32, 48 şi 64 hours. At each milling time
were taken samples for analysis (5 grams). The X-ray diffraction analysis
reveals that after 8 hours of milling the Fe peaks disappear and the Ni phase is
featured in all powder mass. The calculated crystal parameters prove that the
mechanical alloying process induces Ni structure for all powder mixtures after 8
hours of milling resulting a substitution solid solution where some Ni atoms
were replaced with Fe ones.
Cuvinte cheie: aliere mecanică, pulberi Fe Ni, moara planetară
Keywords: mechanical alloying, powder Fe Ni, planetary mill