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Predicting the dynamics of an electrically charged drop impacting a solid surface is of great importance in various industrial applications such as spray coating and painting. An impacting drop decelerates immediately before the touch-down by the lubrication pressure of the intervening air. The pressure build-up forms a dimple resulting in the entrapment of bubbles under the drop. We measured and visualized the dimple and bubble formations using high-speed interferometry and back-light imaging techniques by focusing on the effect of the electrostatic charge on the surface deformation. We clarified that the dimple size decreased, and the kink of the dimple became more flattened with increasing the charge, which resulted in forming a micro-bubble band around a central bubble. By comparing the dimple profile obtained with interferometry and bubble images, we revealed that an air layer, thinner than 266 nm, raptures into small pieces forming a microbubble band while a thicker air layer collapses into a bubble. Replacing a substrate from conductive to dielectric hinders the decrease in dimple volume, confirming Maxwell stress acting between the drop bottom surface and the substrate plays a crucial role in determining the bubble entrapment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Japan Research Association for Textile End-Uses / Sen'i Seihin Shohi Kagaku is the property of Japan Research Association for Textile End-Uses / Sen'i Seihin Shohi Kagaku and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this research, shot-blaster apparatus is intended mechanical milling apparatus by using air blast shot peening method. Normally, Alumina or abrasive powder is used as media particle to clean the product surface in the shotblaster apparatus. In this paper, SUS304L stainless steel powders, the most widely used austenite stainless steel, were intended as shot-blaster media. This SUS304L powder media hit the tungsten carbide by high pressure from air compressor so that is deformed severely. The SUS304L compact was made by spark plasma sintering process. The microstructure and mechanical properties of the SUS304L compacts compared with the conventional compacts prepared using initial powders. The SUS304L powders have plastic deformation on the particle surface after shot-blasting. The deformed powders fractions are increased with increasing shot-blasting time. However, deformed powders fractions are stable at about 70 to 75% after 18 ks of shot-blasting time. The bimodal structure of SUS304L compacts can produced by shot-blasting process because small grain areas are observed in the sintered compact prepared from shot-blasted powders. The tensile results reveal that the SUS304L compacts made by shot-blasted powders exhibit high strength and especially high ductility compared with the conventional SUS304L compact. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Japan Research Association for Textile End-Uses / Sen'i Seihin Shohi Kagaku is the property of Japan Research Association for Textile End-Uses / Sen'i Seihin Shohi Kagaku and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of the Japan Research Association for Textile End-Uses / Sen'i Seihin Shohi Kagaku is the property of Japan Research Association for Textile End-Uses / Sen'i Seihin Shohi Kagaku and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Influence of additive material to surface roughness in turning of sintered steels is not well known. In this study, effect of manganese sulfide (MnS), silica and alumina powder was investigated on a viewpoint of material characteristics near turned surface. The surface roughness of the sintered steel added with MnS was smaller than the others. MnS was extended and dispersed finely in the deformed layer near the turned surface, while silica and alumina were localized but not extended. Nano indentation test showed that the deformed layer of the sintered steel added with MnS had lower hardness in comparison with others. We considered that a tear mark of the cutting chip separated from deformed layer was lowered by MnS and the trace of torn chips, namely the surface roughness became relatively small. However, the deformed layer of the sintered steel added with silica or alumina was close to that of the additive-free sintered steel and the surface roughness became similar to these cases. [ABSTRACT FROM AUTHOR]

Harmonic structure has three dimensional gradient microstructure. The harmonic structure has a heterogeneous microstructure consisting of bimodal grain size together with a controlled and specific topological distribution of fine and coarse grains. In other words, the harmonic structure is heterogeneous on micro- but homogeneous on macro-scales. The harmonic structure design has been applied to structural metallic materials, such as ferrous and non-ferrous materials, via a powder metallurgy route consisting of controlled severe plastic deformation of the corresponding powder and subsequent sintering process. At a macro-scale, the harmonic structure materials exhibited significantly better combination of strength and ductility, as compared to their homogeneous microstructure counterparts. This behavior was essentially related to the ability of the harmonic structure to promote the uniform distribution of strain during plastic deformation, leading to improved mechanical properties by avoiding or delaying localized plastic instability. In addition, the harmonic structure materials also showed many unique deformation behaviors. [ABSTRACT FROM AUTHOR]