Performance Comparison of Al–Ti Master Alloys with Different Microstructures in Grain Refinement of Commercial Purity Aluminum
Three types of Al–5Ti master alloys were synthesized by a method of thermal explosion reaction in pure molten aluminum. Performance comparison of Al–5Ti master alloy in grain refinement of commercial purity Al with different additions (0.6%, 1.0%, 1.6%, 2.0%, and 3.0%) and holding time (10, 30, 60 and 120 min) were investigated. The results show that Al–5Ti master alloy with blocky TiAl3 particles clearly has better refining efficiency than the master alloy with mixed TiAl3 particles and the master alloy with needle-like TiAl3 particles. The structures of master alloys, differing by sizes, morphologies and quantities of TiAl3 crystals, were found to affect the pattern of the grain refining properties with the holding time. The grain refinement effect was revealed to reduce markedly for master alloys with needle–like TiAl3 crystals and to show the further significant improvement at a longer holding time for the master alloy containing both larger needle–like and blocky TiAl3 particles. For the master alloy with finer blocky particles, the grain refining effect did not obviously decrease during the whole studied range of the holding time.
Decomposition of Al2.7Fe0.3Ti in heated Al–Al2.7Fe0.3Ti refiner fabricated by spark plasma sintering and its refining performance
In our previous study, a novel Al-L12-type Al2.7Fe0.3Ti refiner was fabricated by spark plasma sintering (SPS) and its refining performance was studied. It was found that L12-type Al2.7Fe0.3Ti particles can be favorable heterogeneous nucleation sites for Al casts, since the lattice matching between Al2.7Fe0.3Ti and Al is good. It was also found that the thermal stability of heterogeneous nucleation sites affects the grain-refining performance. In this study, the decomposition phenomena of the Al2.7Fe0.3Ti phase in a refiner are studied by heating an Al–Al2.7Fe0.3Ti refiner fabricated by SPS. In addition, the refining performance of a heated Al–Al2.7Fe0.3Ti refiner is investigated.
Urea removal strategies for dialysate regeneration in a wearable artificial kidney.
The availability of a wearable artificial kidney (WAK) that provides dialysis outside the hospital would be an important advancement for dialysis patients. The concept of a WAK is based on regeneration of a small volume of dialysate in a closed-loop. Removal of urea, the primary waste product of nitrogen metabolism, is the major challenge for the realization of a WAK since it is a molecule with low reactivity that is difficult to adsorb while it is the waste solute with the highest daily molar production. Currently, no efficient urea removal technology is available that allows for miniaturization of the WAK to a size and weight that is acceptable for patients to carry. Several urea removal strategies have been explored, including enzymatic hydrolysis by urease, electro-oxidation and sorbent systems. However, thus far, these methods have toxic side effects, limited removal capacity or slow removal kinetics. This review discusses different urea removal strategies for application in a wearable dialysis device, from both a chemical and a medical perspective.