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The chloride permeability of concrete (UHPC) was evaluated by means of the Rapid chloride permeation test and and standard difusion test. The tests are different in the voltage applied for accelerating the transport through the concrete specimen. The permeability strongly depends on quality and curing time of the concrete.

The Czech Republic has a well-developed nuclear programme with two nuclear power plants currently in operation and three operational near-surface repositories serving for the disposal of institutional and operational low- and intermediate-level waste. Spent nuclear fuel will be disposed of in a deep geological repository to be constructed in crystalline or metamorphic rock approximately 500 m below the surface. Czech Ca–Mg bentonites will be used as the buffer and backfilling material. Steel-based materials are currently considered as the reference metallic materials in the Czech disposal canister concept. The preferred design is based on a double-walled canister with an inner shell of stainless steel and an outer shell of carbon-steel. Both parts of the canister must provide mechanical stability; the wall of the carbon-steel canister will be strengthened for corrosion-resistance purposes. The presented work focuses on canister design as confirmed by means of mechanical, thermal and criticality ca...

The aim of this review is to summarize the possibilities of replacing graphite bipolar plates in fuel-cells. The review is mostly focused on metallic bipolar plates, which benefit from many properties required for fuel cells, viz. good mechanical properties, thermal and electrical conductivity, availability, and others. The main disadvantage of metals is that their corrosion resistance in the fuel-cell environment originates from the formation of a passive layer, which significantly increases interfacial contact resistance. Suitable coating systems prepared by a proper deposition method are eventually able to compensate for this disadvantage and make the replacement of graphite bipolar plates possible. This review compares coatings, materials, and deposition methods based on electrochemical measurements and contact resistance properties with respect to achieving appropriate parameters established by the DOE as objectives for 2020. An extraordinary number of studies have been performed, but only a minority of them provided promising results. One of these is the nanocrystalline β-Nb2N coating on AISI 430, prepared by the disproportionation reaction of Nb(IV) in molten salt, which satisfied the DOE 2020 objectives in terms of corrosion resistance and interfacial contact resistance. From other studies, TiN, CrN, NbC, TiC, or amorphous carbon-based coatings seem to be promising. This paper is novel in extracting important aspects for future studies and methods for testing the properties of metallic materials and factors affecting monitoring characteristics and parameters.

Nowadays, the cathodic protection is a common way of additional corrosion protection of buried structures. This protection is usually accompanied by cathodic polarisation on the protective potential of-850 mV(CSE). Its function is to prevent undesirable corrosion rates, in case the coating protection fails. Objective was to predict a state in terms of passivity or activity in which a carbon steel is in. And to do so, there is a monitoring of pH values by amphoteric metals, which would track pH changes of cathodically protected material in a soil. For pH detection, Al and Zn, were used. Main aim was to track corrosion rate of these amphoteric metals as a most reliable way to predict pH changes. Cathodic protection led to higher pH values of model soil located closely to surface of protected material. In case of carbon steel, alkalisation led to passive state and in the same time amphoteric metals could exist in active state. The aim of this work was to clarify usage of monitoring the corrosion rate of amphoteric metals for detection of pH values influenced by cathodic polarisation.Graphical abstract: Fig. 1 Kinetic and thermodynamic demonstration of passivation of cathodically protected steel

It is essential that corrosion monitoring of indoor atmospheres be highly sensitive, especially when corrosion rates corresponding to the lowest standard corrosivity categories are supposed to be identified within one or a few days. The electrical resistance (ER) technique in combination with high sensitivity ER sensors enabled detection of corrosion loss on an atomic scale. The magnetron sputtering method was used to produce sensors equipped with 50 to 800 nm metallic track. The set of developed sensors represent a wide range of materials, e.g. copper, silver, iron, lead and bronze. Laboratory experiments have proven that copper and silver sensors respond to changes in relative humidity and temperature within minutes. Bronze and copper sensors are able to detect changes in concentrations of volatile organic acids, which are common pollutants of indoor atmospheres in museums.

A system for continuous monitoring of atmospheric corrosivity has been developed. An electronic unit measures and records changes in the electrical resistance of a thin metal track applied on an insulating substrate. If the metal corrodes, the effective cross sectional area of the track decreases and the electrical resistance increases. Sensors made of silver, copper, iron/steel, zinc, lead, tin, aluminium, bronze, and brass at thicknesses from 50 nm to 250 m were tailored for environments with different corrosivities. The developed technology proved capable of providing high sensitivity, allowing for real-time corrosion monitoring even in low-corrosive indoor cultural heritage facilities. Laboratory tests showed good reproducibility with the standard deviation of parallel measurements at less than ±20% for metals which corrode uniformly in the tested environments. Several examples selected from a broad testing programme in partner museums, libraries, and other institut ions show successful applications of the logger system for characterization of air quality control in indoor locations, during transport and in temporary exhibitions; assessment of new buildings and storage facilities; and fundamental studies of optimal conservation and storage procedures. A first outline of a classification system for lead, which is particularly sensitive to the presence of carboxylic acids, is given. The technique has a large potential as an independent method for monitoring air quality in facilities displaying and storing valuable objects of cultural heritage.

A logger enabling continuous measurement of corrosion rate of selected metals in indoor and outdoor atmospheres has been developed. Principle of the measurement method is based on the increasing electrical resistance of a measuring element made of the material concerned as its cross-sectional area diminishes due to corrosion. Zinc, iron, copper and nickel sensors at several thicknesses are available. Sensitivity of the corrosion measurement varies from 1 to 10 nm depending on the type and thickness of the sensor. Changes in the air corrosivity can be thus detected within hours or even tens of minutes. The logger lifetime in medium corrosive environments is designed to be 2 years with full autonomy. Data on the sensor corrosion rate are available any time through GPRS connection or by a non-contact inductive reading without the need of retracting the logger from the exposure site.

It is essential that corrosion monitoring of indoor atmospheres should be highly sensitive, especially, when corrosion rates corresponding to the lowest standard corrosivity categories are supposed to be identified within one or a few days. The electrical resistance technique in combination with high-sensitivity electrical resistance sensors enabled detection of a corrosion loss on an atomic scale. Case studies have demonstrated the sensors’ ability to timely inform the users about changes in the atmosphere quality. In confrontation with quartz crystal microbalance technique, resistometric sensors provided better explainable data.

The results are reported of a systematic programme of electrical resistance measurement (ERM) of copper and silver corrosion rates within various museum environments, directed towards developing preventive conservation understanding and practice. Electrical resistivity measurements were made using copper and silver probes for one month and one year in 33 locations, and these are interpreted in comparison with two standards. Advantages and drawbacks of different methods available for the evaluation of the corrosion aggressiveness of indoor air are discussed. Practical solutions are proposed for improving the protection of metal objects collections. Improvements are also proposed to maximize the efficiency and suitability of the measuring device to the very specific applications of cultural heritage collections.