Papers by Keyword: Ferrite

Abstract: Advanced high-strength steels (AHSS) can offer an excellent combination of high strength and light weight for applications including cold forming. These steels may be used in press braking and profile and section manufacturing. The aim of this work is to study the mechanical properties and microstructure of steel used in the manufacturing of roll-formed profiles with decreased radii. In this study, ferritic feedstock steel with 450 N/mm² yield strength, coiled at room temperature, and the sections with wall thicknesses of 7.1 mm and 12.5 mm are studied with middle line radii of 7.5 mm and 13 mm, respectively. Mechanical properties and impact toughness, especially considering the corners of cold-formed profiles, without and with aging (250 °C for 1 h), are studied. Cold deformation on corners is influenced by thickness and tensile strength in aged conditions. Impact energies are at a high level at-40 °C and-60 °C, and aging does influence the toughness but not on the hardness.

Abstract: This study investigated the impact from nitrogen content in backing gases on the microstructure and corrosion resistance of food grade stainless steel weld metal. Three types of backing gases were employed: 100%Ar, 85%Ar+15%N₂, and 100%N₂. Statistical analysis using ANOVA revealed a significant effect from nitrogen content on the ferrite phase fraction within the weld metal microstructures (p-value = 3.5E-05), indicating a reduction in the ferrite phase with increasing nitrogen content. Moreover, increasing nitrogen content positively shifted the pitting corrosion potential, indicating enhanced corrosion resistance. Optical microscopy confirmed lower pit density in samples with nitrogen backing gas as compared with samples with argon backing gas. These findings underscore the crucial role of nitrogen content in backing gases at influencing microstructure and corrosion resistance in stainless steel weld metal, with higher nitrogen levels correlated with improved corrosion resistance.

Abstract: This research investigated the Fe doping effects on the Strontium Titanate (SrTiO₃) structure to improve its photocatalytic activity. The so-called Fe-doped STO photocatalysts with a stoichiometry formula of SrTi_1-xFe_xO₃ (x = 0, 0.01, and 0.05) were successfully fabricated using the coprecipitation method. The XRD characterization confirmed the formation of STO, SrTi_0.99Fe_0.01O₃, and SrTi_0.95Fe_0.05O₃ photocatalysts and the shrinkage crystallite size due to increasing Fe content. The FTIR characterization supported the XRD results, where all samples revealed Sr-Ti-O bonds with no observed Fe-O bonds indicating the successful fabrication and doping. The photocatalytic activity was examined by the degradation of Methylene Blue (MB) dye under UV light for 1, 2, 3, 4, and 5 irradiation times, and the absorbance was determined using a Spectrophotometer instrument. All samples have successfully degraded MB dye where the %degradation linearly increased with longer irradiation times. The results further exhibited that the SrTi_0.95Fe_0.05O₃ sample had the highest %degradation at 75.3% while SrTi_0.99Fe_0.01O₃ samples achieved the highest kinetic rate at 0.2557 min^-1. All Fe-doped samples revealed better photocatalytic activity than the undoped STO, proving that Fe doping could improve the photocatalytic activity of SrTiO₃.

Abstract: This paper reports on the successful synthesis of fine nanoparticles of nickel-substituted lithium-iron ferrites of composition Li_0.5-x/2Ni_xFe_2.5-x/2O₄ (0.2≤ x ≤1.0) by the sol-gel autocombustion method. It has been found that the alternating current (AC) and direct current (DC) conductivity is preferably tuned due to its dependence on temperature and nickel doping. Analysis of the Arrhenius dependences also confirms the appearance of more than one conduction mechanism upon substitution. The predominance of one type of conductivity over another depends on the concentration of the substituting element. Measurement of the magnetic properties has shown that the substitution of Ni²⁺ can significantly change the saturation and residual magnetization. Samples of composition Li_0.4Ni_0.2Fe_2.4O₄ have the highest saturation magnetization (84.08 emu/g), residual magnetization (15.85 emu/g), and the lowest coercive force (0.18 kOe). All the obtained results indicate a significant effect of the substitution of Ni²⁺ ions on the structure and properties of Li_0.5-x/2Ni_xFe_2.5-x/2O₄ ferrite nanoparticles.Photocatalytic properties have been obtained by the degradation of Methylene Blue dye under illumination with a halogen lamp. It is shown that an increase in the content of nickel ions leads to a change in the type of conductivity: from n-type (unsubstituted lithium pentaferrite) to p-type (with substitution x = 0.8 and higher). These systems are characterized by hopping conduction realized by octa-positions according to the mechanisms Fe³⁺+e^-↔Fe²⁺, and Ni³⁺↔Ni²⁺+h⁺. The predominance of one or another mechanism depends on the content of nickel ions. The optical band gap ranges from 1.4 to 2.25 eV. Samples with nickel content x = 0.4 and x = 0.8 have shown the best degradation ability, which is 97% within 160 min for Methylene Blue.

Abstract: Comprehensive metallographic studies of steel forgings with different machinability by cutting with an edge tool were also completed. Structural features and properties of steel were revealed, having adversely influence on tool life and the process of chip formation during cutting. Metal Science criteria have been given for assessing the manufacturability of steel at machining operations. Microstructures of steel with satisfactory and unsatisfactory machinability are presented. The technological parameters of heat treatment of steel 18HGR have been established, causing a show of banding of ferrite-pearlite structure. The thermokinetic diagram shows an area of development of the segregation banding structure. An important role in assessing the manufacturability of steels is shown of the microhardness of individual structural components and the difference in values between them. The best results in machinability by cutting are observed when the microhardness of pearlite is not more than 350 HV, ferrite is not more than 210 HV and the difference in microhardness between these components is not more than 80 HV.

Abstract: Deforestation issues increased dramatically every year specially to produce paper. Therefore, to supplement the limited wood fibre resources, non-wood fibres especially sugarcane bagasse introduced an alternatives resolve for raw material is considered in paper-based industries. This study addresses the analysis of magnetic sugarcane bagasse materials as substitute fibres in papermaking. Paper is generally made with cellulose fibre which has some specific features used for educational, packaging, and cleaning purposes. Sugarcane bagasse (Saccarhum officinarum) is popular for its cellulose, holocellulose, and lignin that far more convenient than wood fibres. Meanwhile, the demands of magnetic material in magnetic papermaking industry has increased due to its excellent mechanical characteristics. As the magnetic paper shows some superiority in properties such as renewable use and folding resistance. The used of filler in this study is to alter the properties such as texture, opacity, brightness, dimensional stability, and overall printability. Thus, the used of ferrite (Fe) magnet as a filler can enhance the paper properties. Ferrite is recognized as a hard-magnetic material with distinct properties such as good mechanical hardness and chemical stability, therefore it is a much more convenient material for magnetic paper production. Through the observation under Scanning Electron Microscope (SEM), the image obtained shows that magnetics sugarcane bagasse paper was more convenient to be used as an alternative for paper making. Next, Fourier-Transform Infrared Spectroscopy (FTIR) recognizes the presence of a functional group of the magnetics sugarcane bagasse paper. Moreover, the chemical properties obtained from this study show that the magnetics sugarcane bagasse was as good as the commercial paper available in the industries. To increase the integrity of the paper, the radiation process by using gamma-ray was done to the paper to see the different for pre and post radiation.

Abstract: Magnetic nanoparticles for thermotherapy must be biocompatible and possess high thermal efficiency as heating elements. The biocompatibility of Mg_0.8Ni_0.2Fe₂O₄ nanoparticles was studied using a cytotoxicity colony formation assay and a cell viability assay. HeLa cells exhibited cytotoxic effects when exposed to three different concentrations of 150 μg/ml, 100 μg/ml, and 50 μg/ml nanoparticles. Therefore, concentrations of 50 μg/ml showed the lowest cytotoxic activity and the lowest toxicity to living cells. In vitro cytotoxicity of samples was then investigated by two methods, colony formation assay and cell viability assay. The Hela inhibited cell growth as 16.8% during heating by magnetic field generators.

Abstract: One of steel 08H14N5M2DL scopes in the industry is an aircraft industry, to be exact, production of racks of the chassis for airplanes and helicopters which test cyclic types of loadings (take-off/landing). Despite the margin of safety which is put at the design of the aircraft, an important role plays, both quality of the material and its ability to save the mechanical properties during all assigned resource for the aircraft. Therefore the development of necessary conditions of production of steel under which the highest mechanical properties and also the ability to save them on the maximum period will be received becomes relevant and today. Work purpose: Identification and prevention of the most significant negative factors having an impact on mechanical properties of steel 08H14N5M2DL in the course of its receiving. In the work, 257 melting of steel of VNL-3 brand in the open IST-0.16 induction furnace with lining from a ground, magnesite brick is investigated. Methods of research are control of the content of austenite and existence of δ - ferrite in structure there were by measurement of values of a magnetic flux density cold and hot tests on the IFSS-1 device and also calculations of the number of products of wear, the solubility of nitrogen in steel VNL-3 and saturation nitrogen. It is revealed that negative impact on mechanical properties of VNL steel – 3 is rendered by nonmetallic inclusions, the maintenance of δ-ferrite and nitrogen. It is established that for stabilization of mechanical properties of steel, aging temperature after tempering in 500 °C allows to support and save steady indicators of mechanical properties. The fact that δ the ferrite exception of solid steel will allow reducing the oxygen content in it not less, than for 0.019% is confirmed owing to what iron crystallizes in γ-phase, passing δ-modification. The presented results confirm prospects of the developed approach in receiving the high-quality steel intended for use in the aviation industry.

Abstract: We conducted comparative tests of the wear resistance of metals operating under abrasive conditions. Samples were cut from the working parts of mixer-pneumosuperchargers. The chemical composition and mechanical properties were determined. To compare samples under abrasive wear conditions, we designed and assembled a carousel installation. The principle of its operation is based on mixing the abrasive medium by the samples being studied with a given speed. Wear resistance was evaluated by weight loss by samples after several test cycles. To determine changes in the structure of the metal during abrasive wear, metallographic studies of the samples were carried out before and after the tests. It is shown that the best complex of service and mechanical properties is possessed by 110G13L steel.

Abstract: This research aims to investigate the effect Si on microstructures and mechanical properties of normalized pressure vessel steel A517 Grade Q. The Si contents were varied from 0.5, 0.9, 1.2, and 1.6. The normalizing process was carried out at 920 °C in 10 minutes. The microstructures were characterized by optical light microscope and Scanning Electron Microscope (SEM), and The mechanical tests were conducted by hardness, tensile, wear, and impact testing machine. The microstructures and mechanical properties were investigated. The results of the microstructures test show that the phases of the material are bainite and ferrite. The increase of Si content will refine and distribute the bainite phase in the ferrite matrix. The mechanical tests show that the Si content will affect the mechanical properties such as hardness, tensile strength, ductility, wear resistance, and toughness. The Increase of Si content from 0.5 up to 1.2 will increase the hardness, tensile strength, and wear resistance, and will decrease the elongation and toughness of the normalized pressure vessel steel A517 grade Q. The mechanical properties seem constant from 1.2 up to 1.6 of Si.