Development of NanoCAP (nano composite advanced particles) technology for high density recording
In this paper, nanosized spherical magnetite particles, with the coercivity force of about 3000 Oe was developed. This material was named NanoCAP (nano composite advanced particles). This study described both magnetic and structural properties of NanoCAP. The crystal structure and the microstructure of the particles were examined using an X-ray diffractometer and high resolution transmission electron microscope, respectively. The obtained magnetization and coercivity of the particles were 89 emu/g and 2900 Oe, respectively. NanoCAP is expected to be the most promising candidate for ultrahigh capacity recording tapes.
Magnetic Properties of Fe16N2 Fine Particles.
Heat conditions for synthesis of Fe16N2 tine particles and the resulting magnetic properties were investigated. Commercial ultra fine γ - Fe2O3 particles were first reduced under hydrogen gas at temperatures between 200°C and 700°C for 8 hours and nitrided under an ammonia-argon mixed gas at 140°C for 24 hours. The powder reduced at 500°C and nitrided at 140°C was identified as nearly Fe16N2 single phase by X-ray diffraction and Mossbauer analysis. Saturation magnetization at room temperature was about 200 emu/g. Maximum coercive force (2250 Oe) was achieved in the Fe16N2 powder with the largest specific surface area.
Experimental investigation of the geotechnical properties and microstructure of lime-stabilized saline soils under freeze-thaw cycling
Abstract The Song-Nen Plain in northeastern China holds one of the three largest expanses of soda saline-alkali soil in the world. Due to its disadvantageous geotechnical properties, the saline soil in this area is unable to meet the needs of construction projects. This study evaluates the stabilizing effect of adding lime to such soils. Specifically, it investigates how the physicochemical and mechanical properties and microstructure of soda saline-alkali soil are altered by lime and how these changes are affected by both freeze-thaw cycling and the duration of curing. The results reveal that adding lime to saline soil transforms clay particles into sand and silt particles and causes the pore size distribution (PSD) to become bimodal, with small-pore and macropore populations. An increase in lime content leads to an increase in the unconfined compressive strength (UCS) but a gradual decrease in both the cation exchange capacity (CEC) and plastic index. Freeze-thaw cycles break up coarse particles and aggregate finer particles, increasing the diameter of macropores and decreasing the USC; however, the effect on specimens with >9% lime is negligible. It is further shown that the geotechnical properties of the soil change immediately after the addition of lime, indicating that the cation exchange reaction takes place very quickly. Furthermore, the pozzolanic reaction leads to an increase in the percentage of sand-sized particles and a decrease in porosity after 28 days of curing. Overall, these results indicate that it is feasible to use lime to improve the engineering properties of soda saline-alkali soil in this area.