Study on the growth mechanism of Bi-2212 ribbon-like thin films on flat Ag substrate by the atomization technique
The growth mechanism of Bi-2212 ribbon-like thin films on flat Ag substrate using an atomization technique was studied. The fine Bi-2212 powders were dispersed on the Ag substrate before the melting process, so as to avoid the change in the composition of the molten phase with distance, which would result in the formation of the impurity phases. Nearly reversible peritectic reaction on cooling causes the formation of well-defined Bi-2212 phase. Based on the results of in situ high temperature microscope observation, the wetting of the molten phase to the growing ribbons was identified as the essential condition for the growth of the ribbon-like thin films.
Growth of Bi–Sr–Ca–Cu–O ribbon-like thin films on sputter-deposited Ag film
Abstract This is a report on the melt growth process of Bi2Sr2Ca1Cu2Ox ribbon-like thin films on sputter-deposited Ag films. Ag films were used as the substrates for this process instead of Ag plates because their flat surfaces are superior to the Ag plate surfaces. Six Ag films on MgO single crystal (0 0 1) were prepared. Their deposition rates ranged from 11.2 to 51.4 A/s. Although the flatness of the Ag films as they were deposited was ∼1 nm independent of the deposition rate, the (0 0 1) texture of the Ag films that had been deposited slowly was superior. After annealing, the films with a faster sputter deposition rate were roughened (>100 nm). On the other hand, even though the roughness of the Ag films at a slower sputter deposition rate increased ( 100 nm). The roughness of the surface allows for further crystal growth during the melting process, which can be attributed to the capillary phenomenon. The results suggest that the wettability is important during the melting process on the Ag surface to the growth of the ribbon-like thin films.
Compressive and flexural properties of hemp fiber reinforced concrete
The compressive and flexural properties of hemp fiber reinforced concretes (FRC) were examined in this paper. Natural hemp fiber was mixed using dry and wet mixing methods to fabricate the FRC. Mechanical properties of the FRC were investigated. The main factors affecting compressive and flexural properties of the FRC materials were evaluated with an orthogonal test design. Fiber content by weight has the largest effect. The method for casting hemp FRC has been optimised. Under the optimum conditions, compressive strength increased by 4 %, flexural strength increased by 9 %, flexural toughness increased by 144 %, and flexural toughness index increased by 214 %.