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.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.