Advances in Materials Science Research. Volume 36

ISBN-13: 9781536148480 / Angielski

Maryann C. Wythers

Opis

In the preliminary study included in Advances in Materials Science Research. Volume 36, a novel fiberglass catalyst with highly dispersed 1-2 nm Pd clusters confined in the bulk of fiberglass at a depth of 10 nm was proposed. In spite of extremely low palladium content, this catalyst showed high performance in the selective hydrogenation of acetylene. Basic research of physicochemical properties of the silicate glass as well as the Pd/FG catalyst revealed that mass transfer of reagents in the bulk of glass does not limit the reaction rate, and the glass has a capability to absorb a large amount of polar or readily polarizable molecules like acetylene but not ethylene. In another study, vaporized materials (such as liquid vapors) were ejected through a nozzle into a vacuum, and liquid clusters with various cluster sizes were formed by adiabatic expansion. The vacuum has an important role in cluster formation, and the fundamental properties of the vacuum and clusters are described in terms of an existence in emptiness. Next, the following operations are discussed: mechanical cutting (with punching dies, guillotines, waterjets and laser beams), clamping, welding, riveting, and the coating of sheet surfaces with insulating layers. A practical laboratory stand for the examination of finished cores used in induction motors, designed by one of the authors at the Wroclaw Branch of the Electrotechnical Institute, is presented. The authors deal with the issue of lead-free solders at high application temperatures, with the aim to study the effect of lanthanides addition on the properties of solders for high application temperatures. The Bi-based solders Bi11Ag2La, Bi2La, Bi2Y were designed and fabricated as innovative soldering alloys. The study of effect of lanthanides in the soldering process was especially oriented toward soldering Al2O3 and ZrO2 ceramic materials. Some examples of errors that can occur in soldering ae listed, while several selected defects are reviewed: non-wettability of the solder pads, dewetting, wrong solder mask design, warpage, head-in-pillow, cracks in the joints, pad cratering, black pad, solder beading, tombstoning, dendrites, voids, flux spattering from the solder paste, popcorning and whiskers. In closing, the authors discuss the development of processing technology for producing electrical steels with increased silicon content, which is considered one of the novel achievements in contemporary materials science dealing with magnetic materials. Commercially available steels produced by JFE Steel Corporation are analyzed.