Influence Of Al203 Particle Mixed Dielectric Fluid on Machining Performance of Ti6Al4V

In this research work, an attempt was made to machine Ti6Al4V titanium alloy utilizing AA6061/10Gr composite tool. The composite tool was fabricated using stir casting technique and Al2O3 particles of size 5µm were incorporated in the dielectric fluid to enhance the machining performance. Experiments were conducted by varying Al203 concentration, pulse on time, current, and pulse off time, and the responses Material Removal Rate (MRR), Tool Wear Rate (TWR), and Surface Roughness (Ra) were recorded. Experiments runs were planned using Taguchi orthogonal array. The results revealed that adding powder increases MRR and TWR owing to the excessive heat generation and bridging effect respectively. The best surface finish was attained due to the increase in spark gap and complete flushing of machined debris. Coating of materials over the machined specimen was observed when the parametric value of Ton was higher than 60s under PMEDM conditions. Pits, craters and cracks were observed on the machined topography which was eliminated when 5g/l of Al2O3 particles were added to dielectric fluid. MEIOT technique was utilized for optimization and it was observed that Ton 15µs, Toff 4µs and current 7A and powder concentration of 10g/l results in best machining performance.

Highly anisotropic thermal conductivity and electrical insulation of nanofibrillated cellulose/Al2O3@rGO composite films: effect of the particle size

Abstract: Nanofibrillated cellulose (NFC) film has received tremendous attention due to its excellent electrical insulation, which shows great application prospects in the field of electronic devices. However, the low efficient heat dissipation of NFC film largely limits its use in advanced applications. In this work, the rGO hybrid fillers loaded alumina (Al2O3) particles with different sizes were synthesized by different drying methods and then they were mixed with NFC to prepare a series of NFC-based composite films. The effect of Al2O3 particle sizes on the thermal conductivity of NFC-based composite films was studied. The results showed that the surface areas of l-Al2O3 particles were smaller than that of s-Al2O3 particles, resulting in the smaller interface thermal resistance and superior thermal conductivity of the film containing l-Al2O3 particles. The NFC-based composite films showed great potential for the applications in thermal management by adjusting the particle size of fillers.

Impact of Al2O3 Particle Size on the Open Porosity of Ni/Al2O3 Composites Prepared by the Thermal Oxidation at Moderate Temperatures

The performance of attractive Ni-based composites can be affected by changing their microstructures, e.g., introducing pores. Here, we report a novel, relatively low-cost process to fabricate Ni/Al2O3 composites with open porosity modified by the size of Al2O3 particles. The mixture of powders was subjected to thermal oxidation twice in air after a maximal temperature of 800 °C was reached in a stepwise manner and maintained for 120 min. The oxidation kinetics were determined thermogravimetrically. The open porosity was evaluated by an Archimedes’ principle-based method. Localization and quantification of NiO, newly formed on the Ni particle surface and acting as a mechanical bonding agent, were explored by scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffractometry. Larger ceramic particles prevented merging of NiO layers on adjacent Ni particles more efficiently; therefore, the open porosity increased from 21% to 24.2% when the Al2O3 particle diameter was increased from 5–20 µm to 32–45 µm. Because both Ni/Al2O3 composites exhibited similar flexural strength, the composite with larger Al2O3 particles and the higher open porosity could be a better candidate for infiltration by molten metal, or it can be directly used in a variety of filtration applications.