Thermoplastic filament winding with online-impregnation. Part B. Experimental study of processing parameters

In part A of this paper, a novel process technology was presented which allows to combine thermoplastic filament winding with online melt impregnation of fibre bundles. In this part, a comprehensive study of process parameters was conducted. Circular glass fibre (GF) reinforced polypropylene (PP) or polyamide 12 (PA12) tubes were produced as sample component. Processing speeds of up to 15 m/min could be achieved in case of GF/PP before a drop in quality of the parts had to be accepted. The present limitation in winding speed is not attributed to impregnation problems but to an excessive rise in force required to pull the fibre tow off the impregnation device. Measures for process improvement and increase in productivity were proposed.     

Some properties of electron beam evaporated amorphous Mo-N films

A series of amorphous Mo-N films was prepared by electron beam evaporation of molybdenum in varying partial pressures of nitrogen and deposited onto substrates cooled to about 80 K. The alloy films were characterized by X-ray diffraction, the superconducting transition temperature,T _c, and the crystallization temperature,T _x. The maximumT _c (8.3 K) and sharpest transition occurred with the minimum nitrogen pressure necessary to form the amorphous structure, as revealed by X-ray diffraction. After annealing the as-deposited films, both bcc and fcc phases were found with the bcc/fcc ratio decreasing with increasing nitrogen partial pressure. Differential scanning calorimetry (DSC) measurements showed significant differences in the shape of peaks associated with either bcc, bcc+fcc, or fcc phases. The temperature,T _x, associated with the fcc crystallization increased with nitrogen content. Heats of crystallization had an average value of about 63 J g^?1. Changes in position of the first amorphous X-ray diffraction peak showed that the amorphous structure was expanded by increasing nitrogen content.     

An investigation of radiation-recrystallization coupling laboratory and field studies

Near-surface faceted crystals are often attributed as being the weak-layer in fatal slab avalanches. To gain a further understanding of these crystals Montana State University researchers collaborated with the Yellowstone Club Ski Patrol to investigate near-surface metamorphism. Detailed weather information as well as daily observations and grain-scale images were collected from January to April, 2008. Several radiation-recrystallization events were observed throughout this period. Near-surface facets were successfully developed using laboratory simulations of recorded field data. A comparison of measured data with a thermal model indicated that natural snow would likely have higher temperature gradients compared to the laboratory snow test given the same environmental conditions. This phenomenon indicates that low-density snow may be conducive, but not obligatory, to form near-surface facets. This work highlights that field and laboratory investigations may be coupled to reveal information not present in the individual studies alone.