Grafting of ethyl α-cyanacrylate on poly(vinyl alcohol)

Because hydrophilic copolymers containing cyanacrylate elements should be useful as components of adhesives in surgery, the conditions of grafting of ethyl α-cyanacrylate on poly(vinyl alcohol) were studied. Two anthraquinone derivatives were applied as sensitizers in UV-initiated grafting; 2,6-disulfoanthraquinone sodium salt proved to be especially efficient. IR spectra and derivatograms of poly(vinyl alcohol-g-ethyl α-cyanacrylate) are described.     

Structural changes in the surface layer of plastic as a result of sliding friction in a metal-thermoplastic system

Studies on structural changes in the surface layer of plastics during internal sliding friction (friction upon seizing) of metalthermoplastic systems have been carried out. These structural changes were carried out by means of polarized light microscopy, density measurements, X-ray diffraction and IR absorption spectroscopy (ATR). They were carried out for high density polyethylene (HDPE), polypropylene (PP) and nylon 6 (PA6). As a result it was found that the formation of completely different structures was caused by internal sliding friction.     

Laser welding with filler material in the form of a wire

The methods for synthesis of arc surfacing using holding, displacing, vibroarc and cutting effects are developed. The concept of waste-free machining by cutting and a number of technological measures (flexible alloying and nano-reinforcement, multi-electrode processes, directional cooling), expanding the technological possibilities of surfacing, is described.     

Single-layer bronze hardfacing with the TIG method

This article presents an assessment of TIG pad welding technology as applied to a steel shaft with a thin single-layer coating of bronze CuSn6. Recommended technological parameters for avoidance of welding imperfections are given. Filled CuSn6 bronze layers were assessed for hardness and consumption volume in terms of friction.     

The effect of retained austenite on the fracture toughness of high-speed steels

The aim of this work was to find the quantitative dependences between fracture toughness K_lc and the volume fraction of retained austenite in the matrix of quenched high-speed steels. The tests were carried out on three model alloys of a different content quotient of Mo: W which, after quenching, were gradually supercooled up to ? 196°C and then tempered at 450°C. Also the measurements of the content of retained austenite in the vicinity of the surface of a sample fracture were carried out. It was determined that after tempering at 450°C the fracture toughness of the matrix of high-speed steels is directly proportional to the content of retained austenite in it. Every 1 % by volume of retained austenite increases the fracture toughness K_lc of the matrix by about 5%, despite the fact that most probably it is completely transformed into fresh martensite in front of a propagating crack. Higher fracture toughness of the matrix of high-speed steels rich in molybdenum should be explained exlusively by a larger content of retained austenite. Transformations in the martensitic part of the matrix of the alloys richer in molybdenum clearly reduce the advantageous effect of retained austenite on this steel feature.     

Recovery of epichlorohydrin and dichloropropanols from waste

A method of recovery of the organic compounds: dichloropropanols, epichlorohydrin, 1,2,3-trichloropropane from epichlorohydrin plant waste has been performed. The method depends on the adsorption of organic compounds in the active carbon and their desorption by allyl chloride. Allyl chloride is desorbed by steam. After desorption the solutions are recirculated to the epichlorohydrin plant.     

Identification of Rheological Parameters on the Basis of Various Types of Compression and Tension Tests

The objective of the project was to determine flow stress on the basis of various plastometric tests. The experiments used uniaxial compression, ring compression, and plane strain compression for two sizes of samples and tensile tests. The material was carbon‐manganese steel, and all the tests were performed at three temperatures (900, 1000, and 1100°C) and at three strain rates for each temperature (0.1, 1, and 10 s^?1). Inverse analysis was applied to the interpretation of the results of all compression tests. The flow stresses obtained from various compression tests were compared resulting in the following observations: consistent results between the tests were observed for low values of the Zener‐Hollomon parameter, but some discrepancies appeared for larger values of this parameter. The sensitivity of the results of inverse analysis with respect to the friction factor was investigated next, and it was concluded that the flow stress determined from ring compression showed the largest sensitivity to friction. This sensitivity was lower for uniaxial compression and plane strain compression of small samples, and no sensitivity was observed for plane strain compression of large samples. Finally, the simulations of the tensile tests were performed using the rheological models determined in compression, and reasonably good results were obtained.     

Einfluß des Molybdäns auf die Zähigkeit von Schnellarbeitsstählen

Unterschiede im Gefüge von Schnellarbeitsstählen der Grundzusammensetzungen (%) 18W-0Mo-1V und 6W-5Mo-2V. Härten von Proben aus je einer Schmelze dieser Stähle und anschließendes Anlassen bei Temperaturen von 250 bis 650°C. Bruchmechanische Biegeprüfungen, quantitative Messung des Carbidteilchendurchmessers, rasterelektronenmikroskopische Untersuchungen und Messung der Oberflächenrauheit. Folgerungen, besonders über kritische Carbidteilchengrößen in Hinsicht auf das Rißwachstum.     

Making decisions in a two-stage identification system with knowledge updating

In this article, an algorithm for updating knowledge in an adaptive system to support decision making is proposed. Taking into account the specific character of the process, a two-stage identification approach is used. The first stage is built for diagnostic purposes, i.e., the estimated parameters in the first-stage relationship are used to make a decision at the second stage. The proposed algorithms to support decision making at the second stage rest on knowledge extracted from human experts and the effects of the diagnosis (based on identification results) at the first stage. To examine the effectiveness of the proposed algorithm, a numerical simulation of a biomedical problem is carried out.