Volume 58 (2014): Edizione 2 (June 2014)

Inorganic compounds were often used to protect wood from wood-decaying fungi and insects (e.g. compounds of arsenic, copper, chromium, zinc or boron) or as a retarder of combustion (e.g. ammonium salts, boron compounds). However, their use may accelerate degradation processes, which may show up as worsening of mechanical properties. The study deals with the impact of selected inorganic compounds (sodium chloride, copper sulphate pentahydrate, boric acid and ammonium sulphate) on cellulose. The samples of cellulose impregnated with the said compounds were subject to artificial aging. The cellulose was monitored for weight changes, changes in colour, values of aqueous extract pH, an average polymerization grade, mechanical properties, elementary composition and the content of bound inorganic compounds. The study was meant to identify stability of the used inorganic compounds in the conditions of artificial aging. The results imply that copper sulphate pentahydrate and ammonium sulphate accelerated degradation of cellulose the most. The effect of boric acid lead to larger deterioration of specimens namely in the conditions of dry aging. Sodium chloride had a negligible impact on the course of degradation. Used compounds continue to be at least partly retained in the cellulose specimens even after rinsing.

Materials for storing nuclear waste are a hot topic all over the globe right now. This study monitors corrosion behaviour of copper as one of the contemplated materials in the Czech bentonite Rokle B75. The tests were carried out in a thermostated cell deaerated with argon at temperatures of 90 and 40°C in the environment of bentonite pore solution, bentonite pore solution with an addition of sulphides and wet bentonite suspension. The scanning electron microscopy, X-ray diffraction, Raman spectroscopy, electrochemical impedance spectroscopy and resistometric methods of corrosion rate measurements were applied. The most compact layer is formed in the environment of bentonite pore solution. The addition of sulphides leads to a significant growth of thickness of the layer of corrosion products and its porosity. However, the porosity decreases towards the layer - metal interface. The layer formed after exposure to the wet bentonite suspension is reported to have the worst parameters. Nevertheless, considering the final temperature of 40°C in the repository, the corrosion rate will still be acceptable.

The work is focused on the evaluation of cadmium layer corrosion according to Boeing specification and how is the status of the underlying material influenced by the corrosion. Plating was applied on the steel panels (type 4130). These metal sheets were partially corroded, therefore there were chosen various surface pretreatment, which removed the corrosion attack and subsequently cadmium plating was carried out. Corrosion neutral salt spray test for 336 hours was done according to ASTM B117.

In the statistical treatment of measured data, factor analysis is often necessary. The methods involved can be used individually to emphasize the basic common factors in the group of variables; the factors produced can be then utilized as input data for other data analysis methods. The number of variables required to describe the system may be lowered, because the original variables may be correlated and, possibly, there is a smaller set of linearly independent variables. Thus, factor analysis is among the possible methods for the data analysis, when dealing with quantitative analytical measurements. Factor analysis of the measured data was used to lower the amount of variables in the analysis of steel; it was found that 94.5 % of the overall variance in the data can be attributed to three factors. Three original variables were assigned to these factors, lowering the number of required variables.

The study summarises the basic information on daguerreotype, the first ever practically used photographic process, which was used mainly in the period 1840 - 1860. Daguerrotype takes advantage of a photosensitive layer of silver halides on a silver layer to capture an image, it uses a reaction of silver with mercury vapours to develop the image. The production process via daguerreotype as described hasn’t changed since its deployment and stabilisation in the middle of 19th century. The properties of a daguerreotype image are given by its soft microstructure, which could have only been described after introduction of the electron microscopy. The susceptibility of daguerrotypes to damage and degradations stems not only from their low mechanical resistance but also from unsuitable conservation interventions and archiving conditions.