Optimized ultrasonic assisted dispersion of un-functionalized titanium dioxide (TiO) nanoparticles (0.5-20wt%) into epoxy resin is reported. The investigation shows that there is a direct relation among nanoparticles content, inter-particle spacing and cluster size of the particles on the glass transition temperature (T) and tensile properties of the prepared nanocomposites. A significant improvement in tensile strength and modulus with minimal detrimental effect on the toughness was observed for the prepared composites, where compared to pristine epoxy resins, about 26% and 18% improvement in tensile strength and strain-to-break %, respectively, was observed for 10wt% particles loading, whereas a maximum improvement of about 54% for tensile toughness was observed for 5wt% particles loaded resins. The investigations found that a strong particle-matrix interface results in the enhancement of the mechanical properties due to leading toughening mechanisms such as crack deflection, particle pull out and plastic deformation.

Titania nanoparticle dispersion and its effect on thermal properties of epoxy-based nanocomposite were examined by producing it via ultrasonic vibration process. Atomic force microscope images of the epoxy/TiO2 nanocomposite revealed a good dispersion of nanoparticle up to an optimum level of loading (10 wt%), which results in its improved glass transition temperature and thermal stability. But, a higher particle loading in epoxy reflects decrease in the glass transition temperature and thermal stability of the nanocomposite, which may be attributed to the significant increase in clustering of the nanoparticles.

This work demonstrates the successful silanization of ZrO2 nanoparticles (ZN) and their incorporation in glass fiber/epoxy composites. Microscopic investigation under transmission electron microscope elucidates antiaggregation and size enhancement of silanized ZrO2 nanoparticles (SZNs). FTIR spectroscopy has been used to demonstrate the chemical nature of the SZNs prepared. EDX results reveal the presence of Si onto SZNs. Incorporation of SZNs shows a strong influence on tensile and flexural properties of hybrid multiscale glass fiber composite (SZGFRP) compared to that of the neat epoxy glass fiber composite (GFRP). A significant variation of tensile strength, stiffness, and toughness of ∼27%, 62%, and 110% is observed with respect to GFRP. Strength and modulus under bending are also enhanced to ∼22% and ∼38%, respectively. Failure mechanisms obtained from macroscopic and microscopic investigation demonstrate reduced interfacial delamination for SZGFRP. Additionally, increased roughness of the fiber surface in SZGFRP laminates produces better interfacial bonding arising from SZN incorporation in laminates. This symptomatic behavior exposes the espousal of organically modified ZrO2 to enhance the interfacial bonding for their use in next generation hybrid laminates.

Dispersion of nanoparticles and its effect on the mechanical properties were investigated by fabricating nanocomposites via mechanical mixing (MM) and ultrasonic dual mode mixing (UDMM) methods. The mechanical mixing of ZrO 2 nanoparticles in epoxy resin was employed using glass rod stirring and the ultrasonic dual mode mixing was employed by ultrasonic vibration along with magnetic stirring to produce ZrO 2 -epoxy nanocomposite. Micrographs obtained using a field emission scanning electron microscope revealed an improved dispersion quality of ZrO 2 nanoparticles especially for the UDMM method. The improvement in dispersion was reflected in much improved tensile and fracture properties of the nanocomposite.

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A new ironmaking concept is being proposed that involves the combination of a rotary hearth furnace (RHF) with an iron-bath smelter. The RHF makes use of iron-oxide-carbon composite pellets as the charge material and the final product is direct-reduced iron (DRI) in the solid or molten state. This part of the research includes the development of a reactor that simulated the heat transfer in an RHF. The external heat-transport and high heating rates were simulated by means of infrared (IR) emitting lamps. The reaction rates were measured by analyzing the offgas and computing both the amount of CO and CO 2 generated and the degree of reduction. The reduction times were found to be comparable to the residence times observed in industrial RHFs. Both artificial ferric oxide (PAH) and naturally occurring hematite and taconite ores were used as the sources of iron oxide. Coal char and devolatilized wood charcoal were the reductants. Wood charcoal appeared to be a faster reductant than coal char. However, in the PAH-containing pellets, the reverse was found to be true because of heat-transfer limitations. For the same type of reductant, hematite-containing pellets were observed to reduce faster than taconite-containing pellets because of the development of internal porosity due to cracking and fissure formation during the Fe 2 O 3 -to-Fe 3 O 4 transition. This is, however, absent during the reduction of taconite, which is primarily Fe 3 O 4 . The PAH-wood-charcoal pellets were found to undergo a significant amount of swelling at low-temperature conditions, which impeded the external heat transport to the lower layers. If the average degree of reduction targeted in an RHF is reduced from 95 to approximately 70 pct by coupling the RHF with a bath smelter, the productivity of the RHF can be enhanced 1.5 to 2 times. The use of a two-or three-layer bed was found to be superior to that of a single layer, for higher productivities.

A new ironmaking concept using iron-oxide-carbon composite pellets has been proposed, which involves the combination of a rotary hearth furnace (RHF) and an iron bath smelter. This part of the research focuses on studying the two primary chemical kinetic steps. Efforts have been made to experimentally measure the kinetics of the carbon gasification by CO 2 and wu¨stite reduction by CO by isolating them from the influence of heat-and mass-transport steps. A combined reaction model was used to interpret the experimental data and determine the rate constants. Results showed that the reduction is likely to be influenced by the chemical kinetics of both carbon oxidation and wu¨stite reduction at the temperatures of interest. Devolatilized wood-charcoal was observed to be a far more reactive form of carbon in comparison to coalchar. Sintering of the iron-oxide at the high temperatures of interest was found to exert a considerable influence on the reactivity of wu¨stite by virtue of altering the internal pore surface area available for the reaction. Sintering was found to be predominant for highly porous oxides and less of an influence on the denser ores. It was found using an indirect measurement technique that the rate constants for wu¨stite reduction were higher for the porous iron-oxide than dense hematite ore at higher temperatures (>1423 K). Such an indirect mode of measurement was used to minimize the influence of sintering of the porous oxide at these temperatures.

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