Petr Dostál

Degradation of polymeric bellows effecting life cycle of constant-velocity joint

ABSTRACT One broken and three new polymeric constant-velocity boots (bellows) being a spare part of a constant-velocity joint in two military vehicles were analyzed to identify basic composition and to determine if composition or structure of broken bellows differ. Infrared spectroscopy, differential scanning calorimetry, and thermogravimetry were used for analyses. Bellows for both vehicles are produced from thermoplastic elastomer. Broken bellows is chemically degraded and material just from the fracture is deformed plastically. The life cycle of bellows depends especially on applied stress and temperature (that about −20°C seems to be critical due to crystallization of soft segments).

INFLUENCE OF ROUGHNESS ON QUALITY MOLYBDENUM DEPOSIT LAYER BY THERMAL SPRAYING

BUJNA MARIAN, PRISTAVKA MIROSLAV, DOSTAL PETR, KORENKO MAROS, KADNAR MILAN. 2016. Infl uence of Roughness on Quality Molybdenum Deposit Layer by Thermal Spraying. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 64(1): 9–14. In this paper we deal with the impact of roughness on the quality of molybdenum layer. Insuffi cient cleaning may result in a poor quality of the sprayed layer. Our aim is to analyze the infl uence of surface roughness on the quality of molybdenum layer thickness applied by thermal spraying. Thermal spraying infl uence several physical and chemical properties of the coating surface. The most important ones include: hardness, density, porosity, corrosion resistance and adhesion. This

Corrosion Resistance of Galvanized Steel in the Environment of a Bioreactor

Abstract The article deals with monitoring the corrosion resistibility of welded materials in the anaerobic fermenter (bioreactor). The main goal of this research is to assess the change of hardness after degradation. The change of hardness occurs in the corrosion environment and it correlates with the corrosion resistibility of material. The purpose of this experiment is to recognize the possibilities of using the CMT welded materials in the defined environment. As an innovative technology the acoustic emission method is used for assessment of surface layer disruption during hardness testing. Aluminium alloy with galvanized steel (AluZinc) was used as an experimental material. The basic materials were welded by the filler material AlSi3.

Acoustic Emission with Testing the Pressure Resistance and Structural Integrity in Mineral Feeds

Abstract This work deals with a specific method of non-destructive testing - acoustic emission. The theoretical part of the article is focused on the underlying principle of this method and its applicability. The experimental part is focused on the research of pressure resistance in mineral feed using acoustic emission. Mineral feed is a condensed cube of rock salt (sodium chloride) with supplementary minerals, which is fed to livestock and game to supply the mineral elements necessary for their health and condition. Acoustic emission gives the overview of internal changes in material structure. With use of specific software we can interpret the acoustic signal and identify the current state of material integrity in real time.