Applied Science Private University

About: Applied Science Private University is a education organization based out in Amman, Jordan. It is known for research contribution in the topics: Catalysis & Population. The organization has 4124 authors who have published 5299 publications receiving 116167 citations.

Three-dimensional printing with nano-enabled filaments releases polymer particles containing carbon nanotubes into air.

Abstract: Fused deposition modeling (FDM™) 3-dimensional printing uses polymer filament to build objects. Some polymer filaments are formulated with additives, though it is unknown if they are released during printing. Three commercially available filaments that contained carbon nanotubes (CNTs) were printed with a desktop FDM™ 3-D printer in a chamber while monitoring total particle number concentration and size distribution. Airborne particles were collected on filters and analyzed using electron microscopy. Carbonyl compounds were identified by mass spectrometry. The elemental carbon content of the bulk CNT-containing filaments was 1.5 to 5.2 wt%. CNT-containing filaments released up to 1010 ultrafine (d < 100 nm) particles/g printed and 106 to 108 respirable (d ~0.5 to 2 μm) particles/g printed. From microscopy, 1% of the emitted respirable polymer particles contained visible CNTs. Carbonyl emissions were observed above the limit of detection (LOD) but were below the limit of quantitation (LOQ). Modeling indicated that, for all filaments, the average proportional lung deposition of CNT-containing polymer particles was 6.5%, 5.7%, and 7.2% for the head airways, tracheobronchiolar, and pulmonary regions, respectively. If CNT-containing polymer particles are hazardous, it would be prudent to control emissions during use of these filaments.

Effect of Zr addition on hot deformation behavior and microstructural evolution of AA7150 aluminum alloy

Abstract: The hot deformation behavior of homogenized AA7150 aluminum alloys containing different Zr contents (0–0.19 wt%) was studied in uniaxial compression tests conducted at various temperatures (300–450 °C) and strain rates (0.001–10 s−1). Microstructural evolution was investigated using an optical microscope, a field-emission gun scanning electron microscope, a transmission electron microscope and the electron backscattered diffraction technique. The results reveal no significant variation in the peak flow stress or activation energy between the 7150 base alloy and the alloy containing 0.04% Zr. With a further increase in the Zr content to 0.19%, the values of peak flow stress and activation energy increased significantly. The materials constants and activation energy for hot deformation were determined from the experimental compression data obtained for all alloys studied. The solved constitutive equations yielded good predictions of the peak flow stress over wide temperature and strain-rate ranges for 7150 alloys with different Zr contents. The dynamic recovery level of the materials was reduced after being alloyed with Zr, which was associated with a decrease in the mean misorientation angle of boundaries and a decrease in subgrain size. The addition of Zr promoted the retardation of dynamic recovery and the inhibition of dynamic recrystallization during hot deformation due to the pinning effect of Al3Zr dispersoids on dislocation motion and to restrained dynamic restoration.