When powder is compacted by a differential speed rolling, the roll speed ratio of the two rolls greatly affects the structure of the compacted product. However, the effect of the roll speed ratio on the structure of the compacted product has not been calculated. In this paper, for compaction process with a differential speed rolling, the weight of the compacted product per unit area was calculated by using a modified Johanson model assuming the velocity gradient of powders, and the calculated values were compared with experimental results. As a result, both the calculated and measured weight of the compacted product decreased as the roll speed ratio increased and the roll gap decreased. It was confirmed that the roll speed ratio dependence and the roll gap dependence of the weight calculated by a modified Johanson model showed the similar trend as those of the experimental results.
To simulate the atmospheric corrosion of Mo-alloying steels in salinity environment, artificial β-FeOOH rust particles were synthesized by aerial oxidation of a mixture of aqueous FeCl2 and MoCl5 solutions at different Mo/Fe molar ratios. Increasing Mo/Fe ratio suppressed the β-FeOOH formation to generate amorphous materials. Added Mo5+ was easily incorporated in the products and remarkably inhibited the crystallization and particle growth of β-FeOOH. Specific surface area of the Mo5+-doped β-FeOOH steeply decreased with an increment of Mo/Fe ratio, meaning the strong aggregation of β-FeOOH particles by adding Mo5+. It is likely, therefore, that atmospheric corrosion of Mo-alloying steels in salinity environment forms the dense, compact and stable rust layer consisting of fine β-FeOOH rust particles on the steel to prevent further corrosion of the steel.
The dispersed state of the conductive additives and the binders, which is a fluorine polymer, in the positive electrode material of the lithium ion battery electrode was evaluated by using an energy dispersive X-ray spectrometer attached to scanning electron microscope with a low accelerating voltage. By applying a low accelerating voltage, it is possible to reduce the penetration depth of electron beam into the target material and improve the energy resolution of light elements such as carbon and fluorine. Therefore, it was clarified that the dispersion state of the conductive additives and the binders around one particle of the active material could be observed as element distribution images, and the dispersion state could be quantitatively evaluated as the coverage by image processing. By estimating the coverage of conductive additives and binders on the surface of active materials depending on the dry mixing conditions, it was suggested that this technique could be used for structural design and process optimization of electrodes for improving battery performance.