Structural Analysis of Al-CNT Nanocomposite Using X-Ray Diffraction

The development of metal-matrix composites (MMCs) has mainly been driven by the growing needs of modern applications for lightweight materials yet strong enough to withstand high service loading. On the other hand, carbon nanotubes (CNTs) presenting excellent combination of mechanical and physical properties have already performed as an excellent strengthening to reinforce MMCs. In present study, an air induction furnace was used to fabricate aluminum-multiwall carbon nanotubes (Al-MWCNTs) composite. The process was benefited for better dispersion of the CNTs, which was validated during microscopic studies. Additionally, the mechanical properties were significantly augmented i.e., the yield strength from 64±3 to 115±2 MPa, the tensile strength from 82±2 to 125±3 MPa for matrix material and Al-CNTs composite, respectively. The structural analysis including, grain size, crystallite strain and dislocation density were investigated using X-ray diffraction to relate with the improvement in the properties.

Structure, thermal and electrical properties of Fe-B-Co-Nb-Ni-Si high-entropy metallic glass

New nanostructured Fe25B17.5Co21.35Nb3.65Ni25Si7.5 high-entropy metallic glass is synthesized by dint of splat-quenching technique. The estimated cooling rate is ~106 K/s. The coherently scattering domain size (crystallite size) of films of Fe 25B17.5Co21.35Nb3.65Ni25Si7.5 high-entropy metallic glass estimated by the Sherer formula is ~ 3 nm. The high-entropy metallic glass shows a high temperature of glass transition Tg ~ 800 K and the initial temperature of crystallization Tx ~ 863 K. After annealing to ~ 1010 K (above the crystallization temperature) and subsequent slow cooling, the amorphous films crystallize with the formation of several crystalline phases. The temperature dependencies of electrical resistivity of the Fe25B17.5Co21.35Nb3.65Ni25Si7.5 films indicate the occurrence of phase transformations. The phase transformation temperature (temperature of crystallization) is ~ 869 K. This value agrees well with the value obtained from the differential thermal analysis.

Effect of Calcination Temperature on Photocatalytic Activity of Synthesized TiO2 Nanoparticles via Wet Ball Milling Sol-Gel Method

In this work, TiO2 nanoparticles were successfully synthesized with narrow size distribution via a wet ball milling sol-gel method. The effect of calcination temperature on photocatalytic activity was observed from particle size, crystallite size, and phase transition of TiO2 nanoparticles. Increasing calcination temperature increased particle size, crystallite size, and the crystallinity of synthesized TiO2. Phase transition depended on variation in calcination temperatures. A two-phase mixture of anatase and brookite was obtained with lower calcination temperature whereas a three-phase mixture appeared when calcination temperature was 500–600 °C. With higher temperature, the rutile phase kept increasing until it was the only phase observed at 800 °C. Anatase strongly affected the photocatalytic activity from 300 °C to 600 °C while the particle size of TiO2 was found to have a dominant effect on the photocatalytic activity between 600 °C and 700 °C. A mixture of three phases of TiO2-600 exhibited the highest methylene blue degradation with the rate constant of 9.46 × 10−2 h−1 under ultraviolet (UV) irradiation.

Carbothermic reduction of mechanically activated NiO-carbon mixture: Non-isothermal kinetics

The effect of mechanical activation on the carbothermic reduction of nickel oxide was investigated. Mixtures of nickel oxide and activated carbon (99% carbon) were milled for different periods of time in a planetary ball mill. The unmilled mixture and milled samples were subjected to thermogravimetric analysis (TGA) under an argon atmosphere and their solid products of the reduction reaction were studied using XRD experiments. TGA showed that the reduction of NiO started at ~800? and ~720? in un-milled and one-hour milled samples respectively whilst after 25h of milling it decreased to about 430?. The kinetics parameters of carbothermic reduction were determined using non-isothermal method (Coats-Redfern Method) for un-milled and milled samples. The activation energy was determined to be about 222 kJ mol-1for un-milled mixture whilst it was decreased to about 148 kJ mol-1 in 25-h milled sample. The decrease in the particle size/crystallite size of the milled samples resulted in a significant drop in the reaction temperature.

Physical Properties of Nanocrystalline MoS2 and WS2 Particles Produced by CO2 Laser Pyrolysis

Nanocrystalline powders of 2H-MoS2 and 2H-WS2 with average particle size 5 and 9 nm, respectively, have been produced using C02laser pyrolysis. Typical production rate for these nanoparticles is 2g/hr. Particle size, crystallite size, and the structural phase were determined using X-ray diffraction(XRD), transmission electron microscopy(TEM), and Raman scattering. Particle size effects may have been observed in the Raman-active modes (WS2 and MoS2) and in the band-edge excitons (MoS2).