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Effect of rare-earth co-doping on the microstructural and magnetic properties of BaFe12O19

Güler P., Ertuğ B., İpek-Işıkcı N., Kara A.

Advances in Materials Science

2020

Vol. 20, nr 3(65)

23--35

Ba0.85(La,Y)0.15Fe12O19 hexaferrite magnets were produced using the powder metallurgy method. The phase analysis of the ferrite magnets was carried out by X-ray diffraction (XRD) technique. A single hexaferrite phase was present in both samples as revealed by XRD patterns. The microstructural evolution in the hexaferrite samples was examined using Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-Ray Spectroscopy (EDS). The grain morphology altered with the sintering temperature. Room temperature ferrimagnetic hysteresis curves were obtained by Vibrating Sample Magnetometer (VSM). The crystallite size and the lattice parameters (a,c) were also calculated after sintering at 1150ºC and 1250ºC. Saturation magnetizations, Ms were determined to be 48.60 emu/g and 52.95 emu/g for the samples sintered at 1150ºC and 1250ºC, respectively whereas the remanent magnetizations, Mr were 29.26 emu/g and 31.17 emu/g. The coercivity, Hc decreased from 3.95 kOe to the value of 2.44 kOe with the sintering temperature due to the increase of the crystallite size. The squareness ratios (Mr/Ms) of the ferrimagnetic samples were different because the uniaxial anisotropies altered after sintering at 1150ºC and 1250ºC. The maximum energy product, (BH)max dropped from 35.81 kJ/m3 to 27.38 kJ/m3 when the sintering temperature increased. This result can be attributed to a combination of higher magnetization and the lower coercivity.

The effect of filter type on filling during Low Pressure Die Casting: a numerical study

Yavuz H., Kara A., Çubuklusu H. E., Çe Ö. B., Aybarç U.

Journal of Achievements in Materials and Manufacturing Engineering

2016

Vol. 75, nr 2

71--77

Purpose: Effect of filter types on filling during low pressure die casting researched to find optimal filtration design for wheel casting process. Design/methodology/approach: Three types of filters, which are commonly used during low pressure die casting for light alloy aluminium wheel production, investigated with numerical simulation. In addition, numerical simulation for without filter is made for control variable. According to numerical simulation results, filling time, molten metal velocity results are used to define suitability of the molten metal for wheel casting. Thirteen Control points and two filtration areas generated to calculate the molten metal velocities before and after the filtration areas. Findings: Three different filtration designs for aluminium wheel casting compared according to molten aluminium velocity results of numerical simulation in terms of flow of melt. Filtration design with flat filter is the optimal filtration design for aluminium wheels casting, according to numerical simulations. In addition, combination of other filters with flat filter is suggested to find optimal filtration design according to performance of filters during low pressure die casting. Research limitations/implications: 0.5 m/s velocity for molten metal is accepted as a critical maximum limit for reliable casting according to literature search on aluminium casting. No field test was done in this study. Originality/value: Effect of flow properties on casting quality is promising research field and the effect of filters is part of this research field.