Ustav Kovovych Materialu A Korozniho Inzenyrstvi

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Ustav Kovovych Materialu A Korozniho Inzenyrstvi

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Kovaleik T.,Ustav kovovych materialu a korozniho inzenyrstvi | Gonda A.,Ustav kovovych materialu a korozniho inzenyrstvi | Stoulil J.,Ustav kovovych materialu a korozniho inzenyrstvi
Koroze a Ochrana Materialu | Year: 2013

The study deals with the possibility to apply a new type of duplex steel FeCr20Mn4Ni2N (LDX 2101) as concrete reinforcement. The study compares it with other materials used for concrete reinforcement, especially in terms of mechanical and corrosion properties. Tensile strength, yield strength, ductility and susceptibility to corrosion cracking were mechanical properties subject to the assessment. Resistance to crevice and pitting corrosion was assessed by the electrochemical noise method and exposure tests in a model concrete pore solution with the addition of chlorides and by measurements of corrosion potential, polarization resistance and impedance spectroscopy in concrete bricks, which either did not contain any chlorides or contained chlorides in the amount of 3 wt.% cement as a reference. The steel FeCr20Mn4Ni2N shows high-strength characteristics. In terms of corrosion resistance, it has a similar behaviour as common steel FeCr18Ni8. Only the FeCr18Ni10Mo2 steel shows a passive behaviour in the environment of concrete contaminated with a high content of chlorides. © 2013, Versita. All rights reserved.


Sefl V.,Ustav kovovych materialu a korozniho inzenyrstvi | Rapouch J.,Ustav kovovych materialu a korozniho inzenyrstvi | Stoulil J.,Ustav kovovych materialu a korozniho inzenyrstvi
Koroze a Ochrana Materialu | Year: 2012

The paper studied potential substitutes to sodium dichromate acting as an inhibitor for calcium chloride-based cooling solutions. Mixtures of anodic (molybdate, phosphate, silicate) and cathodic inhibitors and oxidizing substances facilitating formation of a compact magnetite layer (nitrates, nitrites) were used as alternatives. Effi ciency of the inhibitors was studied at fi rst through accelerated measurements of the polarization resistance. The inhibitors for long-term exposure tests were chosen based on the measurements. The combination of “passivating” nitrate and ceric cation acting as the cathodic inhibitor seems to be ideal. This mixture shows a similar decline of the corrosion rate as dichromate. © 2012, Versita. All rights reserved.


Joska L.,Ustav kovovych materialu a korozniho inzenyrstvi | Fojt J.,Ustav kovovych materialu a korozniho inzenyrstvi | Moravec H.,Ustav kovovych materialu a korozniho inzenyrstvi
Koroze a Ochrana Materialu | Year: 2013

Various forms of diamond-like carbon layers have been widely used in industrial applications and there are numerous potential opportunities of their utilisation in biomaterial applications. The DLC layers are bio-inert. It is assumed that a certain level of bioactivity could be achieved by alloying with bioactive metals (Ti, Zr, etc.). The paper studied the impact of DLC layers alloying with zirconium on corrosion properties of coated systems and on the interaction with a simulated body fl uid. The tests were performed in a physiological solution (untreated pH, pH=4.2, pH=4.2+200 ppm F-) and simulated body fl uid. Composition of the surface was assessed by photoelectron spectroscopy (XPS), the electrochemical response was evaluated by electrochemical impedance spectroscopy (EIS). The concentration of zirconium was 7.4 % at. on the surface of the layers and the metal was in an oxidised form. Corrosion response of alloyed layers differed signifi cantly from that of the unalloyed DLC, the behaviour of which corresponded more to zirconium. The systems showed high corrosion resistance in saline solutions, however, the presence of fl uoride ions destabilised the layers. After the exposure to the simulated body fl uid, XPS tests indicated a slight increase of Ca-P concentration on the surface of alloyed specimens compared to the unalloyed specimens. This result was confi rmed by EIS tests. DLC layers alloyed with zirconium are highly resistant to corrosion under ambient conditions and in the environment with lowered pH (as a result of infl ammation). The results imply that alloying lead to changes in terms of bioactivity. Further testing is required to confi rm these results. © 2013, Versita. All rights reserved.


Prusa F.,Ustav kovovych materialu a korozniho inzenyrstvi | Vojtech D.,Ustav kovovych materialu a korozniho inzenyrstvi | Kucera V.,Ustav kovovych materialu a korozniho inzenyrstvi | Bernatikova A.,Ustav kovovych materialu a korozniho inzenyrstvi
Chemicke Listy | Year: 2017

Mechanical alloying and subsequent compaction via spark plasma sintering belongs to prospective combination of two methods capable to produce materials with enhanced mechanical properties, as compared with their conventionally cast equivalents. During this processes, a maximum effort is focused to maintain refined microstructure and to preserve this character even after compaction. Resulting materials are characterized by high hardness, compressive strength or excellent thermal stability. From several materials prepared at our Department, the Al-20Si- 16Fe and Al-10Si-21Fe alloys achieved hardness of 400 HV 30 and compressive strength of ca. 1000 MPa; moreover, these materials exhibited quite a unique anomaly of the yield drop during the compressive test at elevated temperatures. The cobalt-based alloy represented by the Co-26Cr-6Mo-0,25C alloy showed an even higher hardness (650 HV 30) and compressive strength reaching 3100 MPa. The positive influence of short-term mechanical alloying was demonstrated by the first observation of quasicrystaline phase present in the Al-24Cu-13Fe alloy, which arose after 90 minutes of the process. The procedures mentioned can be used even to prepare the Ni-Ti alloys, till now usually prepared by vacuum induction or arc melting, with required phase compositions and intensively refined microstructure with a very low value of porosity. © 2017, Czech Society of Chemical Engineering. All rights reserved.


Novikova D.,Ustav Kovovych Materialu A Korozniho Inzenyrstvi | Kouril M.,Ustav Kovovych Materialu A Korozniho Inzenyrstvi | Msallamova S.,Ustav Kovovych Materialu A Korozniho Inzenyrstvi | Stoulil J.,Ustav Kovovych Materialu A Korozniho Inzenyrstvi | Strnadova N.,Ustav Technology Vody A Prostredi
Koroze a Ochrana Materialu | Year: 2016

Concentrating of pore bentonite water as a result of water evaporation at the hot container surface is expected when the bentonite cover of the permanent nuclear waste container is being gradually saturated. The study assesses the influence of an extent of the pore water enrichment by chloride and sulphate ions up to a multiple of a hundred of their equilibrium concentration. An increase of concentration of these ions does not imply an increase of the electrolyte aggressivity automatically. A minimum of corrosion resistance was observed at triplicate concentration at all temperatures, 40, 70 and 90°C. Even more significant impact on corrosion behaviour was recognized for composition of anoxic atmosphere above the electrolyte. Contrary to nitrogen, the mixture of nitrogen and carbon dioxide remarkably elevates the electrolyte's corrosion aggressivity. © by M. Kouřil 2016.


Svadlena J.,Ustav Kovovych Materialu A Korozniho Inzenyrstvi | Boryskova S.,Kabinet Restaurovani Fotografie FAMU
Koroze a Ochrana Materialu | Year: 2015

Unsuitable storage conditions and use of materials which may be a source of pollutants in indoor environments are major threats to the long-term preservation of historic metal objects. Materials proposed for use in protecting and storage of museum or archive collections need to be sufficiently verified in terms of safety for the protected objects before these materials can be safely recommended. One of the basic techniques used for the purpose of testing of new materials (and verifying of those that are already in use) is the Oddy test whose advantages lies in its simple requirements for the experimental equipment and a possibility to modify this method for a particular use. In this work, a variant of the Oddy test was applied with a modification for a specific case - evaluation of materials used for recasing of daguerreotypes. Besides the commonly used visual assessment, electrochemical reduction of corrosion products on the exposed samples was used to compare the Oddy test results. The results indicate that the influence of the test materials is minor compared to the influence of the state of the daguerreotypes surface. This conclusion is consistent with expectations about safety of the tested materials that are used in conservation practice for the protection of archival and historical photographic collections.


Formanek J.,Ustav Kovovych Materialu a Korozniho Inzenyrstvi | Jandova J.,Ustav Kovovych Materialu a Korozniho Inzenyrstvi | Sis J.,SVUM a.s.
Chemicke Listy | Year: 2012

The aim of the study is to review hydrometallurgical and partly pyrometallurgical technologies of the Zn and Mn recovery from spent Zn/MnC 2 batteries. Main attention was devoted to basic hydrometallurgical operations such as leaching, precipitation, solvent extraction and electrolysis, which are described in patents and literature. Compared with pyrometallurgical processes, hydrometallurgy is a well-established and efficient method for the recovery of not only Zn and Mn but also other battery components such as steel, plastics and paper.


Novak P.,Ustav kovovych materialu a korozniho inzenyrstvi
Chemicke Listy | Year: 2012

This review summarizes recent research of intermetallics in the Department. The research is focused on hightemperature materials, shape memory alloys and hydrogen storage materials. In the case of high-temperature intermetallics, the development of TiAl-Ti5Si3 and NiAl-Al2O3 composites and Fe-Al-Si alloys is described. Powder metallurgy using reactive sintering has been established as an innovative and promising method for easy preparation of the materials. This method is currently tested and optimized for NiTi shape memory alloys. In the case of NiTi alloys for medicinal implants, surface treatment was developed to improve their corrosion resistance in body fluids and biocompatibility. Another important property of intermetallics (such as LaNi5 or Mg2Ni) is their ability to reversibly store hydrogen. In hydrogen storage, hydrides (e.g. Mg2NiH4) are formed. Hydrogen can be released from the materials by heating. The current aim is to develop an easy and efficient method of hydrogen storage and to to lower the hydrogen release temperature.


Pecenova Z.,Ustav Kovovych Materialu A Korozniho Inzenyrstvi | Kouril M.,Ustav Kovovych Materialu A Korozniho Inzenyrstvi
Koroze a Ochrana Materialu | Year: 2016

Historical lead artefacts (small figurines, appliques, bull (metal seal) can be stored in depository and archives in inconvenient storage conditions. The wooden show-case or paper packagings release volatile organic compound to the air during their degradation. These acids, mainly acetic acid are very corrosive for lead. The thin layer of corrosion products which slows atmospheric corrosion is formed on lead surface in atmospheric condition. In presence of acetic acid vapour the voluminous corrosion products are formed and fall off the surface. These corrosion products do not have any protection ability. The lead could be protected against acid environment by layer of "metal soup" which is formed on surface after immersion in solution of salt of carboxylic acid for 24 hours. The solutions of acids (with vary long of carbon chain) and their salts are examined. Longer carbon chain provides better efficiency convers layer. The disadvantages are low solubility of carboxylic acids in water and bad abrasion resistance of formed layer. © 2016 Pecenová Z. et al.


Moravec H.,Ustav kovovych materialu a korozniho inzenyrstvi | Fojt J.,Ustav kovovych materialu a korozniho inzenyrstvi | Filip V.,Ustav kovovych materialu a korozniho inzenyrstvi | Joska L.,Ustav kovovych materialu a korozniho inzenyrstvi
Chemicke Listy | Year: 2014

Ti implants have become an important instrument in handling various problems associated with the loss of flexibility of a joint system. Having replaced a damaged joint with an endoprosthesis reduces pain, restores flexibility and improves the patient's quality of life. The implantbone integration may be a complicated and lengthy process. Therefore, the state of the material surface is of vital importance. Ti can be treated electrochemically to produce a tubular nanostructure, which can later be modified to achieve bioactivity. Moreover, the large adsorption surface enables anchoring of biologically active substances and pharmaceuticals. The nanostructure and its further modifications could facilitate and strengthen the implant-bone integration, and thus shorten the healing process. The article describes the preparation of nanostructures and summarizes the knowledge of Ti surface treatment.

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