The Visco-Elastic Behavior of PA+PAI Composites with Fiber Glass after UV Degradation

The polymeric composites on the base of the PA+PAI filled by glass fibres are usually used in automotive industry and also exposed to natural atmosphere. The research is focused on resistance study of the mentioned composites in simulated atmospheric conditions. The tested specimens contented 10, 20 and 30 % of the glass fibres and they were exposed in UV box with defined time and intensity of UV radiation and temperature. The mentioned factors have a considerable influence on utility and lifetime of product made of the polymeric composite. The effect of the exposition on the composites behaviour was evaluated microscopically, by rheological measurements and impact tests. By the rheological measurements the changes of visco-elastic parameters (complex viscosity, moduli of elasticity and plasticity) were studied after different times of exposition in the UV box as well as chosen mechanical properties

Corrosion Resistance of AISI 316Ti Stainless Steel Subjected to Shot Peening with and without Pickling in Various Chloride Environments

Surface conditions of materials affect the chemical, physical and mechanical properties of stainless steels. The main interest of this paper is to focus on corrosion properties of the AISI 316Ti stainless steel treated by shot peening and shot peening and pickling. In the last years shot peening has been widely used as a method improving fatigue properties of components under cyclical load. Because surface finishing has strong effect on corrosion susceptibility of stainless steels, e. g. pitting and created pits can initialize cracks, it is important to analyse corrosion behaviour of the material in question. In this study, the tested surfaces were characterized by SEM, EDX analyses, measurement of surface free energy and roughness. Corrosion properties were investigated in various environments by exposure, potentiodynamic cyclic and EIS tests

Corrosion Resistance of AISI 316Ti Stainless Steel Subjected to Shot Peening with and without Pickling in Various Chloride Environments

Surface conditions of materials affect the chemical, physical and mechanical properties of stainless steels. The main interest of this paper is to focus on corrosion properties of the AISI 316Ti stainless steel treated by shot peening and shot peening and pickling. In the last years shot peening has been widely used as a method improving fatigue properties of components under cyclical load. Because surface finishing has strong effect on corrosion susceptibility of stainless steels, e. g. pitting and created pits can initialize cracks, it is important to analyse corrosion behaviour of the material in question. In this study, the tested surfaces were characterized by SEM, EDX analyses, measurement of surface free energy and roughness. Corrosion properties were investigated in various environments by exposure, potentiodynamic cyclic and EIS tests

Influence of degradation process on rheological characteristics of polymer materials

Rheological properties of thermoplastic polymer materials before and after exposure in chemical solution were evaluated using Frequency sweep test, which monitors changes in viscoelastic properties of polymers with respect to their molecular structure and their behavior in thermoplastic processes. As experimental material thermoplastic polyethylene and polypropylene samples were used and subjected to influence of n‑hexane solution for period of 3 and 6 months. Measurements were performed using oscillating rheometer Physica Rheometer MCR 301 and carried out at the temperature of 160 °C and 180 °C. Degradation process resulted in changes of complex dynamic viscosity, storage and loss modulus, changes in molar mass and its distribution which sufficiently prove the rheological changes.</p

PITTING CORROSION OF STAINLESS STEEL AT THE VARIOUS SURFACE TREATMENT

<em>The stainless steel surface treatment is very important with regard to its pitting corrosion susceptibility. An effect of various types surfacing on pitting corrosion resistance of AISI 304stainless steel is investigated in this work. The samples of the tested material are turned, blasted, peened, grinded and a half of them are pickled to achieve higher purity of surfaces and better quality of passive film. Eight types of different finished surfaces are tested by electrochemical and immersion tests to determine corrosion behaviour in conditions where pitting is evoked by controlled potential and second by solution with high redox potential. By this way the effect of mechanical and chemical surface treatment on the resistance to pitting corrosion, character, size and shape of pits are compared in the conditions of different mechanisms of corrosion process.</em><span> </span

Effect of Rare Earth Cerium Addition on Oxidation Behavior of Co-Al-W Alloys at 800°C

The γ/γ′ Co-based alloys are a new class of cobalt superalloys, which are characterized by remarkable high temperature strength owing to strengthening by γ′-Co3(Al, X) phases. In this investigation, the effect of cerium addition on oxidation behavior of model Co-Al-W alloys was studied. The introduction of Ce aimed at improvement of the oxidation resistance of γ′-forming Co-based superalloys. The minor additions of cerium (0.1, 0.5 at.%) were added to the base alloy Co-9Al-9W. The alloys were prepared via induction vacuum melting (VIM). Further, a primary microstructure of the alloys was analyzed with particular regard to a segregation of Ce. The thermogravimetric analysis (TG) under non-isothermal conditions was used to preliminary estimate the oxidation behavior of alloys at different temperatures. During experiment, differential thermal analysis (DTA) was performed simultaneously. After this test, cyclic oxidation expermients was carried out at 800°C for 500 h. In as-cast state, Ce segregates to interdendritic areas and forms intermetallic phases. The effect connected with melting of interdendritic precipitates was observed at 1160°C. Ce-containing alloys were less prone of oxide spallation. Moreover, oxidation rate of these alloys substantially decreased after 100h of oxidation, whereas mass of the sample corresponding to base alloy continued to increase

INFLUENCE OF AISI 316Ti STAINLESS STELL SURFACE TREATMENT ON PITTING CORROSION IN VARIOUS SOLUTIONS

Investigation of the surface treatment effect on the resistance of AISI 316Ti stainless steel to pitting corrosion is presented in this paper. The grinded surfaces without additional chemical treatment, grinded and pickled, grinded, pickled and passivated surfaces are tested. The corrosion tests are carried out by exposition in solution which evoke pitting and by electrochemical cyclic potential - sweep method. According to the results the surface treatment has a great influence on the resistance of the tested material to pitting. It is not possible to estimate the best surface treatment because behavior of AISI 316Ti stainless steel with different surface state depends on the mechanism of corrosion processes which vary in the used experimental methods