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In this study, an increase in the reflection loss (RL) value for SrFe(11.9-x)In0.1Snx/2Znx/2O19 samples (x = 0; 0.10; 0.35 and 0.50) is reported. The X-ray diffraction (XRD) pattern of all samples confirmed that the SrFe(11.9-x)In0.1Snx/2Znx/2O19 samples (x = 0, 0.10, 0.35, and 0.50) posses polycrystalline with single phase. We have demonstrated that co-substitution of Zn2+ and Sn4+ ions with a fraction of x = 0.10 reduced the coercivity of the pure nano strontium hexaferrite (SHF) from 346.80 kA/m to 50.34 kA/m. The substitution of Fe3+ ion by Sn2+ and Zn4+ affect the coercivity decreased significantly. Meanwhile, the saturation magnetization and remanence slightly decreases. Hence, the decreasing of coercivity cause the reflection loss (RL) increase from -16.43 dB to -25.62 dB. We believed the RL value can be increased efficiently by reducing the coercivity of the sample obtained by co-substitution of Zn2+ and Sn4+ ions to Fe3+ in the main phase of SrFe11.9In0.1O19.

Ni-TiN/Si3N4 composite coatings on tungsten carbide were prepared by electrodeposition. The influences of electrodeposition temperature at 35 – 45 °C on coating microstructure and its impact to the mechanical and tribology properties were investigated to optimize the process parameter. A compact morphology of coatings gradually increased with increasing electrodeposition temperature that was addressed to the finer Ni crystallite size which resulted from co-deposition of TiN and Si3N4 particles. The finer crystallite size caused the increase of coating hardness with the highest (8.86 GPa) was achieved for the sample deposited at 45 °C. However, from the result of wear rate test, it was shown that the lowest wear rate (28.5 μm) was observed on the sample deposited at 40 °C.

Composite of two phases with crystal grains of titanium nitride (TiN) and amorphous of silicon nitride (Si3N4) had shown an improvement of mechanical properties as shown by composite layer of nickel (Ni) and TiN. In this study, Ni-TiN/Si3N4 composite layer on tungsten carbide bar have been prepared by using electrodeposition to study the effect of current density on the microstructure and mechanical properties of the layer. The optimum properties of composite coating with no crack morphology and maximum hardness was shown by the sample electrodeposited at current density of about 2.5 mA/cm2. The high hardness was attributed to the nickel crystallite size refinement

Microwave absorption properties of double layer magnetic absorbers based on BaFe12O19 (BFO) and BaFe10CoZnO19 (BFCZO) have been investigated in X-band (8.2–12.4 GHz) frequencies. The BFO and BFCZO were prepared by using a solid state reaction process. The crystalline structures were investigated by X-ray diffraction (XRD), The complex permittivity and permeability are determined using Vector Network Analyzer (VNA) in a range from 8.2 GHz to 12.4 GHz. The double layer magnetic absorbers, composed of the BFO as matching layer and the BFCZO as absorption layer, with a total thickness of 5 mm, showed an effective reflection loss (RL) an effective absorbing bandwidth below –5 dB.

In order to enhance a new microwave absorbing capabilities in the X-band frequency range, polycrystalline magnetic materials of BaFe12O19 barium hexaferrite were fabricated through conventional ceramic method and the Fe3O4 powder from iron sand were prepared through magnetic separation after milling process by using planetary ball mill. Microwave absorbing capabilities of multilayer absorbers, composed of BaFe12O19 barium hexaferrite and the Fe3O4 powder, with a total thickness of 10 mm, were investigated by a vector network analyzer (VNA) in the range of 8.2 –12.4 GHz. According to transmission line theory, reflection of microwave radiations from multilayer magnetic materials is calculated. The reflection loss (RL) strongly depends on thickness of multilayer absorbers and showed an optimal RL. Keywords : BaFe12O19, Fe3O4 powder, reflection loss, multilayer absorbers.

Microwave absorption characteristics of double layer of barium hexaferrite attached on the silica to from a composite on the basis of wave propagation theory have been investigated. Barium hexaferrite, BaFe12O19, was synthesized through ceramic method from stoichiometric mixtures of BaCO3 and Fe2O3 as precursors. The mixture was pelletized under the pressure of 10 MPa and sintered at 1100 °C for 5 hours. Silica in the forms of powder was purified by using HCl. The crystal structure of the samples was characterized using X-ray diffraction (XRD), microstructure was examined using scanning electron microscope (SEM), hysteresis curves recorded by PERMAGRAPH techniques, whereas the microwave absorbing properties for X-band was recorded using a vector network analyzer (VNA). Relative complex permeability and permittivity, and reflection loss values were calculated at given thickness according to transmittance line theory within the range 8.2–12.4 GHz. Based on this study, the layer dimension and frequency that results in low reflection loss can be estimated from the material properties of the barium hexaferrite/silica composite material.