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Effect Of Boron Powder Purity On Superconducting Properties Of Mgb2, Xun Xu, Meng J. Qin, Konstantin K. Konstantinov, Dayse Dos Santos, Wai Kong Yeoh, Jung Ho Kim, S. X. Dou
Effect Of Boron Powder Purity On Superconducting Properties Of Mgb2, Xun Xu, Meng J. Qin, Konstantin K. Konstantinov, Dayse Dos Santos, Wai Kong Yeoh, Jung Ho Kim, S. X. Dou
Faculty of Engineering - Papers (Archive)
The effect of the properties of starting boron powders on the superconducting properties of MgB2 has been studied. The 92% and 96% pure powders produce lower surface reactivity and larger particle size than the 99% boron powder, as can be seen from Brunauer–Emmett–Teller (BET) and scanning electron microscopy (SEM) results, indicating that the low purity powders cannot be used to archive the same superconducting properties as those of samples made from pure 99% boron powder. However, the purity of 92% and 96% boron powders can be improved by using a simple chemical process, leading to enhanced magnetic critical current …
Magnetorheological Properties Of Aqueous Ferrofluids, Yongbo Yang, Lin Li, Guang Chen, Weihua Li
Magnetorheological Properties Of Aqueous Ferrofluids, Yongbo Yang, Lin Li, Guang Chen, Weihua Li
Faculty of Engineering - Papers (Archive)
The nanosized magnetite particles were synthesized by means of a coprecipitation method and used to prepare the aqueous ferrofluids with various volume fractions. The magnetorheological properties of the aqueous ferrofluids have been investigated as a function of magnetic field. Under steady-state shear, the apparent viscosity for all of the ferrofluids exhibited a shear thinning behavior. But the Bingham model was invalid since the ferrofluids did not show a yield stress before they began to flow. However, the shear stress increased linearly with shear rate after a critical shear rate, showing a Bingham-like behavior. A Bingham-like yield stress, which was obtained …