Papers by Keyword: Fe₂SiO₄

Abstract: Metal matrix composites have grown rapidly with their usefulness in many applications for industries. The present research aims to study the formation of Fe₂SiO₄ and pearlite phases, the reaction product of iron-silica sand nanoparticles composites. In this study iron based silica sand nanoparticles composite with 5, 10, 15 and 20wt.% of silica sand nanoparticles were developed using powder metallurgy technique being sintered at 1100°C. It was observed during the X-Ray Diffraction (XRD) and XPS analysis that the reaction between iron and silica sand nanoparticles forms the Fe₂SiO₄ phase. Field Emission Scanning Electron Microscopy (FESEM) analysis at higher magnification also reveals the formation of pearlite phase. The presence of liquid phase sintering is also observed with frozen liquid spots at microstructure of iron-silica sand nanoparticles reaction.

Abstract: Red scale is the main surface defect of hot-rolled silicon steel plate due to the formation of fayalite. Studies have been done on high temperature oxidation of Fe-Si alloy, but effect of temperature on structure of outer Fe oxide layer is not fully discussed. Thermogravimetric analyzer (TGA) was used to simulate isothermal 60-min oxidation process of Fe-2.2Si alloy under air condition at 700°C-1200°C. Cross-sectional scale morphology and elemental distribution of the oxide layer were investigated by electron probe microanalysis (EPMA). It is found that in order to observe internal oxide precipitates clearly it is helpful that the sample is etched with nitric acid solution in alcohol firstly and then etched with hydrochloric acid solution in alcohol. At 700°C-1150°C outer Fe oxide layer is mostly composed of Fe2O3 and at 1200°C it consists of FeO + Fe3O4 + Fe2O3 + mixture of FeO/Fe2SiO4.

Abstract: The oxidation behavior of Fe–Si alloys at 1073K in air was investigated. The oxidation kinetics described by the parabolic rate law of diffusion controlled oxidation and the oxidation rate decrease with the increasing Si content. Fe-Si alloys were oxidized for different times at 1073K to obtain the same scale thickness of approximately 30μm. Observations of scale cross-sections indicated the structure of oxide scale and elemental distribution in oxide scales strongly depends on Si content. The oxide scale on Fe-Si alloys with low Si content consisted of three layers with an outer Fe₂O₃, an intermediate Fe₃O₄ and an inner FeO and some voids were formed in Fe₃O₄ and FeO layers. The Si-rich oxide layer was formed at the scale/alloy interface of Fe-Si alloys with high Si content. Furthermore, the amount of internal oxidation zone increased with the increasing Si content. Observations of scale cross-sections indicated that the structure of oxide scale and elemental distribution in oxide scale strongly depend on Si content.

Abstract: This study investigates on the characterization and joining behavior between glass and KOVAR alloy with fiber laser. Due to the different chemic bonds and thermal expansion coefficients, the oxide layer plays an essential role in this process. First, surface treatments under different conditions have been discussed. It’s indicated that when the two textures (the square block and the strip phase) appeared on the KOVAR surface, the joinability of KOVAR alloy enhanced. Then, considering about three laser process parameters (beam scan speed, laser power and focus position) by the orthogonal experimentation, the result indicated that the possibility of this joining technology. Finally, the fractures graphs were observed by LEXT OSL 3000. By analyzing the FeO-SiO2-Fe phase diagram and XRD on the fractures, it displayed that a new chemical substances (Fe2SiO4) had formed which was considered as the key-materials for a good glass-to-KOVAR alloy joint.

Abstract: Hardness of oxide scales on Fe-(0, 0.5, 1.5, 3.0)Si alloys was studied at room temperature after oxidation at 1273 K for 18 ks in oxygen, and at 1073 and 1273 K for 180 and 1080 ks in dry air, by micro-Vickers hardness measurements. After oxidation at 1273 K for 18 ks, high-temperature hardness of oxide scales on Fe-(0, 1.5, 3.0)Si alloys was also measured at 1273 K. Oxide scales on Fe-Si alloys were mainly Fe2O3, Fe3O4, FeO and Fe2SiO4. Hardness of Fe2O3, Fe3O4 and FeO on Fe was 6.7, 4.0 and 3.5 (GPa), respectively, and hardness of Fe2O3 on Fe-Si alloys slightly increased with increasing silicon content at room temperature. At 1273 K, hardness of Fe3O4 and FeO on Fe was 0.08 and 0.05 (GPa), respectively, and hardness of Fe2O3 on Fe-1.5Si alloy was 0.32 (GPa), and that of Fe2O3 and Fe2SiO4 on Fe-3.0Si alloy was 0.53 and 0.63 (GPa), respectively.