Spark plasma sintering of CNT-NiAl nanocomposites – Process parameter, densification mechanism, and grain analysis

The densification process and grain analysis of consolidated NiAl-CNT composites at 1000 °C, and at varied heating rates from 50 °C/min to 150 °C/min was investigated. The results revealed the effect of heating rate on the densification behaviour of the samples. The displacement of the composites decreased from 3.39 mm to 2.63 mm with increasing heating rate, while the porosity increased by 69% at rapid heating rate. The grain analysis of the sintered samples through the electron backscattered (EBSD) technique indicates the evolution of bigger grains as the heating rate proceeds higher. Furthermore, the mean grain size of the consolidated composites increased from 3.93 μm, to 8.05 μm due to the concentration of defects. Interestingly, there was no texture or predominance of any color evolution in the sintered materials.

Non-equilibrium fractal growth of MoS2 for electrocatalytic hydrogen evolution

Non-equilibrium fractal growth of MoS2 was induced by establishing an extremely Mo rich chemical vapor deposition (CVD) environment using a rapid heating rate in a confined reaction space.

Rapid microwave synthesis of Pb5(VO4)3X (X = F, Cl, Br and I) vanadinite apatites for the immobilisation of halide radioisotopes.

ABSTRACTMicrowave dielectric heating was utilized to synthesize potential host phases for halide radioisotopes. Synthesis of Pb5(VO4)3I was successfully achieved, without the use of a sealed container, using a modified domestic microwave oven (DMO) operating at 2.45 GHz. Rapid synthesis of Pb5(VO4)3X (X = F, Cl, Br) was also achieved using a commercially available microwave muffle furnace, also operating at 2.45 GHz. The combination of rapid heating rate and inverse temperature profile characteristic of microwave heating was found to promote formation of the target phases whilst retarding the volatilization of the halide species. Pb5(VO4)3I ceramic bodies produced in the DMO exhibited a heterogeneous zoned microstructure, whereas Pb5(VO4)3X phases with X = F, Cl, and Br fabricated in the microwave muffle furnace were dimensionally uniform suggesting this could be a promising route to fabricating single phase, dense halide containing ceramics.

Effects of Heating Methods on Recrystallization Texture of an Al-Mg-Si Alloy

The cold-rolled sheets of the Al-Mg-Si Alloy were annealed for recrystallization in the box furnace and the bath furnace respectively, then the microstructures were observed and the recrystallization textures were investigated with the orientation distribution functions (ODFs). The results show that after recrystallization annealing at slow heating rate the coarse a-Al grains and the strong recrystallization texture composed of Cube+nd25 components and the {011}<323> components were formed in the sheets of the Al-Mg-Si alloy, and after recrystallization annealing at rapid heating rate the fine a-Al grains and the weak or almost random recrystallization textures were formed.

Gas Evolution of Corn Kernels and Paper Sludge From Biomass Gasification and Pyrolysis

Gasification of biomass has become an area of key interest as it is a reasonably quick and direct way of converting the material into a fuel source that works directly in many industrial systems. The purpose of the present work is to explore gasification and pyrolysis behavior of corn kernels and paper sludge. For both corn kernels and paper sludge, low temperature gasification behavior was studied. Due to corn’s low ash fusion temperature, ∼1400 C, gasification is typically undertaken at temperatures near 1000 C, and most of the chemical mechanisms are similar down to ∼500 C. Here, tests were performed with pyrolysis temperatures from 400–800°C, at 1 atm and a rapid heating rate. The evolution of CO and CO2 were measured throughout the pyrolysis process. Results show a direct correlation between temperature and equivalence ratios and the composition of the gas byproduct for both biomasses. CO production increases with an increase in temperature while CO2 shows no temperature correlation. No hydrogen was observed, as would be expected for the short experimental residence time (0.2 seconds).

Rapid Consolidation of Nanophase Al2O3 and an Al2O3/Al2TiO5 Composite

ABSTRACTA rapid consolidation technique has been utilized in producing single phase AI2O3 in less than 10 minutes at 1400°C resulting in a grain size less than 500 nm. TiO2 has been added in hopes of obtaining Al2O3/Al2TiO5 nanocomposites in sintering times less than 30 minutes. The sintering process involves resistance heating of a graphite die containing the powder at heating rates of about 10 °C/s. The resistance heating step is preceded by a preparatory step consisting of DC voltage pulses applied across a prepressed powder compact. The retention of the nanostructure is attributed to the rapid heating rate although the possible effect of the DC pulses are also discussed. An Al2O3/Al2TiO5 composite has been produced during a short anneal immediately following sintering of an Al2O3/TiO2 nanocomposite. Substantial grain growth has been observed to occur during the transformation taking the composite to the microcrystalline regime.