Structural features of near equiatomic FeCo-2V semi-hard magnetic alloy prepared by MIM technology

The structural properties of a magnetically semi-hard near equiatomic FeCo-2wt%V (FeCoV) alloy produced by Powder Injection Moulding (PIM) (option by fine metal powder - Metal Injection Moulding (MIM) technology) were investigated in this paper. Starting granulate was prepared by mixing FeCoV powder with a low-viscosity binder. After injection, the green samples were first treated with a solvent and then thermally with the same aim of removing the binder. MIM technology was completed by high-temperature sintering for 3.5 hours at temperatures from 1370 OC to 1460 OC in a hydrogen atmosphere, which provides the necessary magnetic and mechanical characteristics. The influence of sintering temperature was investigated concerning the aspects of the processes of structural transformation by the methods of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The appearance of an intense diffraction peak of the α'-FeCo phase (crystal structure type B2) was registered for all investigated samples. Structural parameters particle size Dmax, Feret X, and Feret Y exhibit constant increase with increase of sintering temperature

Structural properties of FeCoV alloys produced by PIM / MIM technology

FeCoV alloys with high saturation magnetization and high Curie temperature, making them useful for high-temperature and power-dense applications (e. g. aviation device). In this study, we report the results of observing the structural properties of 49Fe49Co2V alloy produced by PIM / MIM technology. The starting granulate was prepared by mixing FeCoV powder with a low-viscosity binder. After injection, the raw “green” samples were first treated with a solvent and then thermally with the same aim of removing the binder. MIM technology is completed by high-temperature sintering of “brown” samples for 3.5 hours at temperatures from 1370 OC to 1460 OC in a hydrogen atmosphere, which provides the necessary magnetic and mechanical characteristics. Depending on the sintering temperature, structural parameters of particle size Dmax, Feret X, Feret Y were investigated and analysed

Ispitivanje strukturnih svojstava legure FeCoV metodom skenirajuće elektronske mikroskopije - SEM

U radu su ispitivani strukturna svojstva legure 49Fe49Co2V proizvedene PIM/MIM tehnologijom, tako što je polazni granulat pripremljen mešanjem FeCoV praha sa niskoviskoznim vezivom. Nakon brizganja sirovi uzorci su najpre tretirani rastvaračem a zatim i termički s istim ciljem odstranjivanja veziva. MIM tehnologija je završena visokotemperaturskim sinterovanjem tokom 3,5 sata na temperaturama od 1370 °C do 1460 °C u atmosferi vodonika, kojim se obezbedjuju potrebne magnetne i mehaničke karakteristike. Strukturna svojstva veličine čestica Dmax, Feret X, Feret Y su ispitivana u zavisnosti od temperature sinterovanja

Magnetically soft and semi-hard materials

This study focuses on two ferromagnetic materials as representative of soft (MnZn ferrites) ceramics and semi-hard (FeCo-2wt%V) alloys, both with unique properties in a wide specter of magnetic materials. Recently, a variety of technologies have been examined for MnZn ferrite production: Powder/Ceramic Injection Moulding (PIM/CIM), chemical co-precipitation method, conventional ceramic processing, sol-gel or microemulsion. MnZn ferrites are one of the most common electronic ceramics for application as a material for microwave components (radiofrequency transformers, antennas, transducers, inductors, magnetic fluids, sensors…). They attracted attention due to the wide range of relative magnetic permeability values (from 103 to 104), high electrical resistivity (consequently low magnetic losses) as well as high thermal stability (high saturation magnetic flux density at high temperatures (Bs > 0.4 T @ 100 OC) and a relatively high Curie temperature (about 230 OC). Toroidal samples with dimensions appropriate for applications in microelectronics (inner diameter 3.5 mm, outer diameter 7 mm, height 2 mm) exhibit very stable maximum magnetic permeability in the frequency range from 50 Hz (μr ≈ 480) to 10 kHz (μr ≈ 450) @ 200 A/m. Active power referred to unit mass of about 30 W/kg was recorded at a frequency of 1 kHz (@ 280 mT. Those results were competitive with the catalog data for MnZn components devoted to applications in electronics. Magnetically semi-hard near equiatomic FeCo-2V iron-cobalt based alloy is known for its exceptional combination of high values of saturation magnetic flux density BS and Curie temperature TC (about 950 OC - it is a unique alloy with this property). Binary alloys of Fe − Co systems containing 33-55 wt.% Co are very brittle, but the addition of about 2 wt.% V prevents transformation into an ordered superlattice structure and enables a relatively high value of electrical resistivity (V as alloying element provides very good mechanical and suitable electrical properties compared to other alloying elements, W, Ti, Mo, Mn, Ta, Cu). The XRD patterns of FeCo-2wt%V (FeCoV) alloy produced by Metal Injection Moulding (MIM) technology exhibit the main diffraction peak of the α'-FeCo phase (crystal structure type B2) which increases with an increase in sintering temperature up to 1460 OC. The mechanical hardness does not coincide with the magnetic hardness, i.e. the material with the highest HV10 (value of 348) shows the lowest coercive force HcJ (about 18.4 Oe). Magnetic hardness is associated with the magnetic obstacles that prevent easy movement of magnetic domain walls (“pinning” effect). However, for mechanical hardness, the movement of dislocations, i.e. the prevention of this movement, is crucial (the elements in microstructure are highly efficient in blocking the movement of dislocations, but not that of the Bloch magnetic domain walls). As the hysteresis losses are proportional to the frequency (~ f) and eddy-current losses are proportional to the square of frequency (~ f2) it was performed separation between these two components from total magnetic power (active) losses. Numerical fitting of this functionality on frequency was performed and analyzed, as intermetallic FeCoV components can be used competitively in strategic applications, for example, the aerospace motor rotor

10.5937/tehnika1703383L= Development of methods for traffic simulation of telecommunication processes in IRITEL over 45 years

This paper summarizes the programs intended for simulation of traffic processes in different telecommunications systems. These programs are developed, implemented and verified by the members of the Institute IRITEL through numerous scientific papers and doctoral dissertations taken during 50 years of the Institute activities. Two main areas of traffic simulations are related (but not limited) to the analyses of switching systems and mobile telephony systems