Wyniki wyszukiwania - Biblioteka Nauki

1

Ocena właściwości ochronnych powłok lakierowych analiza wyników badań impedancyjnych

100%

Kolek Z.

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nr nr 383

99-109

XX

Przedstawiono analityczne i graficzne metody analizy impedancji wyników testu opartego na teorii liniowego obwodu elektrycznego. Zaprezentowano zasady określania parametrów elektrycznego schematu zastępczego w układzie metal-powłoka lakierowa - elektrolit. Wyniki pomiarów impedancyjnych przedstawiono graficznie w postaci diagramów Nyquist i Bode'a.

EN

The analytical and graphical methods of the analysis of the impedance test results based on the linear electric circuit theory have been presented. The principles of determining the electric parameters of the metal-protective coating-electrolyte system have been given. The Nyquist and Bode diagrams have been shown.(original abstract)

2

Badania destrukcji powłok emalierskich i ich wykorzystanie w ocenie jakości wyrobów emaliowanych

51%

Chochół A.

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nr nr 133

146

XX

Odporność chemiczna powłok emalierskich nakładanych na wyroby z blachy stalowej jest jednym z najważniejszych kryteriów ich jakości. Od niej głównie zależy czas używania danych wyrobów oraz ich niezawodność. Celem pracy było zidentyfikowanie określonych procesów destrukcyjnych, zachodzących podczas symulacyjnych badań nad emalią, aby następnie analitycznie ustalić przyczyny ich powstawania. Opracowanie modeli procesów destrukcyjnych i wyjaśnienie przyczyn występowania kolejnych etapów tych procesów umożliwia ocenę metod stosowanych obecnie do badań chemoodporności emalii jak i sposobów przeciwdziałania tym zjawiskom. Poznanie tych procesów może mieć wymierne korzyści ekonomiczne w postaci wydłużenia trwałości wyrobów emaliowanych oraz przyczynić się do rozwiązania problemów ekologicznych związanych z ograniczeniem zanieczyszczenia środowiska naturalnego.

EN

In view of the good protection that enamel coatings give to base metal, counteracting the aggressive effect of various media, enamel coatings are widely used in food industry, pharmaceutical chemistry, automotive industry, electronics, and even in building engineering. They are most popular, however, on the houseware, like kitchen ware, bathtubs, sinks, gas ovens etc. Though characterised by high chemical resistance, enamel coatings are also prone to gradual destruction. Therefore, for many years, various research centres have been and are carrying out the studies which as their main target have an improvement of the resistance to chemical attack of enamel coatings applied onto the steel sheet products. This resistance is one of the most important criteria of their quality, determining the life of enamelled products and their failure-free performance. In the case of enamelled ware, the destruction is mainly due to the presence of aggressive compounds contained in food products. In reference literature numerous instrumental methods have been described which enable an assessment of the chemical resistance of enamel coatings. They are usually based on simulation tests, in the course of which a gradual and well-controlled destruction of coatings is observed. By quantitative and qualitative analyses of variations in some selected parameters, the degree of the chemical resistance of enamelled coatings is measured. Yet, great discrepancies in the applied methods and procedures, based on a selective evaluation of the effects of corrosion, make the comparison of results and their correct interpretation quite impossible. To verify the methods which determine the degree of chemical resistance of the enamel coatings it is necessary to study in detail the processes of destruction that take place in these enamels, using to this end a causal-consecutive approach. Therefore, the main aim of this study was development of models describing the phenomena of destruction which occur in various types of enamel coatings. The study was carried out on enamel coatings which differed in composition, were prepared from various raw materials and manufactured by various technological processes. It was mainly devoted to testing of the chemical resistance in acid media, which are most frequently used in practice, especially in food products which are either stored or processed in enamelled ware. A model simulating the processes of corrosion proceeding in these coatings was developed. As etching agents, various acids (acetic, citric, lactic and oxalic) were used in various concentrations. The processes of destruction proceeding in enamel coatings were examined by various methods combined with simultaneously carried out morphological examinations of the externa! film of enamel, applying a scanning electron microscope (SEM) coupled with an energy dispersive X-ray microprobe (EDX). Due to the examinations it was stated that the external layers of enamel coatings differed in respect to their morphological structure. The differences in the structure were mainly responsible for different course of the destruction processes which were noted to occur in simulation tests. The morphological examinations done for the external layers of the investigated enamels in function of the etching time enabled establishing which of the elements would be the next one to undergo the process of diffusion. The process of diffusion occurs according to some strictly determined mathematical functions, and it causes changes in the chemical constitution of coatings. This is the reason why some physical changes take place in the coating, resulting finally in its destruction. In simulation tests the processes which usually take place in enamel coatings have been presented in the form of various models of corrosion which describe the, proceeding during etching, phenomena of destruction. Two models, typical of the enamels characterised by the external structures heterogeneous and homogeneous, were prepared. It has been proved that the successive diffusion of elements does not depend on their ionic radii. The force with which the acid used in simulation tests attacks the enamel depends on the value of pH, on dissociation constant and on the stability constant of complex combinations of anions of these acids with aluminium. In this study, also the methods used most frequently in an assessment of the chemical resistance of enamels were subjected to verification. The profilogrammometric examinations, the degree of light reflection, and the degree of whiteness are not applicable in every case in determination of the chemical resistance of enamel coatings. In some cases, the examined values of these parameters result in an erroneous interpretation of how far the processes of destruction are advanced. As a result of the carried out instrumental examinations and theoretical analyses, a change in the methodology applied so far for determination of the chemical resistance of enamel coatings was proposed. (original abstract)

3

Badanie jakości wyrobów emaliowanych

51%

Chochół A.

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nr nr 427

19-28

XX

Omówiono badania opinii konsumentów na temat aktualnego stanu jakości wyrobów emaliowanych, a następnie podjęto próby określenia postępu korozji wybranych powłok emalierskich w warunkach laboratoryjnych.

EN

In part one of the paper the results of questionnaire surveys are presented. The inquiry concerned the quality assessment of enamelware. The respondents expressed their opinions about selected parameters of enamel. Next, the mechanism of enamel corroding and the possibility of measuring that parameter are analysed. The results of studies on corrosion advancement with regard to selected enamel coatings in various time intervals are presented. The paper ends with the conclusions drawn from questionnaire surveys and laboratory studies. (original abstract)