Search results for "Whisker"
showing 5 items of 15 documents
Ceramic materials wear mechanisms when cutting nickel-based alloys
1999
Abstract In this paper the performances of some commercial ceramic inserts when cutting AISI 310 steel are investigated and compared to those of a traditional carbide based tool. The most important wear mechanism in the ceramic inserts is related to the segmented edges of the chips that abrade a notch at the end of the cut zone. Alumina–zirconia inserts are very sensitive to this kind of wear, whereas tools made of Sialon and alumina with SiC whiskers exhibit slightly better performances despite the concomitant chemical wear mechanisms.
Superconducting transition of single-crystal tin microstructures
2001
Single-crystal superconducting microstructures have been fabricated. The resistances of tin whiskers were measured in a multiprobe configuration. Contacts were made of copper, gold, or niobium films using e-beam lithography followed by a lift-off process. Structures with normal metal probes showed unusual behavior: below the critical temperature of bulk tin, the resistance decreases in distinct steps and does not reach zero even when cooled down to 1 K. The origin of these phenomena is not clear but is likely related to a proximity effect.
Wear of Ceramic Tools When Working Nickel Based Alloys
1996
In order to improve the toughness of alumina materials, various trials have recently been made. These include toughening by the addition of zirconia and of significant amounts of titanium carbide to ceramic oxide Al2O3 and the more recent use of nitride based ceramics, which have resulted in an increase of fracture toughness and in a significant improvement of ceramic tool performance. Another very recent way of improving ceramic materials consists in adding SiC whiskers to Al2O3 matrix. This composite material is also suitable for machining nickel based alloys. In order to evaluate and to qualify these materials some test cycles have been carried out in continuous cutting conditions, emplo…
Adaptive Whisking in Mice
2021
Rodents generate rhythmic whisking movements to explore their environment. Whisking trajectories, for one, appear as a fixed pattern of whisk cycles at 5-10 Hz driven by a brain stem central pattern generator. In contrast, whisking behavior is thought to be versatile and adaptable to behavioral goals. To begin to systematically investigate such behavioral adaptation, we established a whisking task, in which mice altered the trajectories of whisking in a goal-oriented fashion to gain rewards. Mice were trained to set the whisker to a defined starting position and generate a protraction movement across a virtual target (no touch-related tactile feedback). By ramping up target distance based o…
Bi-2212 and Y123 highly curved single-crystal-like objects: whiskers, bows and ring-like structures
2012
High-temperature superconducting objects of Bi2Sr2CaCu2O8 and Y Ba2Cu3O7 highly curved in the ab-plane, such as curved/kinked whiskers, bows and ring-like structures, were obtained within a solid?liquid?solid (SLS) grass-like growth mechanism. As-grown objects are crystals with three-dimensional epitaxy similar to conventional single crystals: they can be viewed as crystal parts ?cut? from a conventional rectangular crystal. Between our curved objects and conventional crystals, whiskers or thin films there are some differences in the superconducting properties induced only by the shape factors and no new physics is observed. Some details of the growth mechanism are discussed, emphasizing cu…