scholarly journals In-situ study of the corrosion process of biodegradable magnesium alloys

2021 ◽  
pp. 18-25
Author(s):  
P. N. Myagkikh ◽  
◽  
E. D. Merson ◽  
V. A. Poluyanov ◽  
D. L. Merson ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Magnesium Alloys ◽  
Human Body ◽  
Corrosion Damage ◽  
Az31 Alloy ◽  
Corrosion Process ◽  
Ex Situ ◽  
Zk60 Alloy ◽  
In Situ Methods

The interest in magnesium and its alloys considerably increases in recent years. These materials have a unique complex of properties: light-weight and strength make magnesium alloys promising structural materials for the aircraft industry and space application, and ability to reabsorb in vivo conditions and good biocompatibility allow producing biodegradable surgical implants of magnesium alloys, which can resorb in a human body without detriment to health. The materials for such demanding applications require detailed investigation of their properties, such as corrosion, including the kinetics of corrosion rate and staging of corrosion damage on the surface. To obtain a full view of the corrosion process, in addition to common ex-situ methods such as the corrosion rate evaluating using the weight loss method and the morphology corrosion damage investigation by optical or confocal laser scanning microscopy (CLSM), it is important to use modern in-situ methods. In-situ methods allow obtaining data immediately during the experiment and not after its completion. The authors carried out a comprehensive study of the corrosion process of the commercial ZK60 and AZ31 magnesium alloys in the simulated human-body environment (temperature, corrosion media composition, circulation of corrosion media) using in-situ methods, including hydrogen evolution corrosion rate evaluating and video-observation of a sample surface. The results show that AZ31 alloy is more corrosion-resistant than ZK60 alloy. Moreover, AZ31 alloy is prone to filiform surface corrosion, and ZK60 alloy exhibits severe pitting corrosion. Based on the comparison of the data obtained by in-situ and ex-situ methods, the authors concluded on their main differences and features.

scholarly journals Corrosion Properties of Biodegradable AZ31 and ZK60 Magnesium Alloys: In Situ Study

2021 ◽  
Vol 6 (1) ◽  
pp. 3
Author(s):  
Evgeniy Merson ◽  
Vitaliy Poluyanov ◽  
Dmitry Merson ◽  
Pavel Myagkikh
Keyword(s):  
Corrosion Rate ◽  
Real Time ◽  
Hydrogen Evolution ◽  
Magnesium Alloys ◽  
Laser Scanning Microscopy ◽  
Ex Situ ◽  
Confocal Laser ◽  
Time Interval ◽  
Surface Observation

Biodegradable magnesium alloys are promising materials for application in medicine. The corrosion rate and type of corrosion are among the most important properties for this kind of materials. The fine-grained biodegradable alloys AZ31 (hot-rolled) and ZK60 (extruded) were studied in the present work with the use of in situ methods including the hydrogen evolution corrosion rate measurement and real-time surface observation as well as ex situ methods such as the weight loss assessment and the post-mortem examination by confocal laser scanning microscopy. The experimental methods included immersion test in SBF (0.9% NaCl aqueous solution) during 120 h with 37 °C with recirculating corrosion media. The hydrogen evolution was measured with a burette with a constant time interval of 1 hour. The real-time surface observation was carried out with a high-resolution camera. The measurement of pH level was done twice a day. Corrosion rate curves, 3D morphology of corroded morphology and video recordings showing evolution of corrosion damage have been obtained. As a result, ZK60 was found to be less corrosion-resistant and addicted to pitting corrosion, whereas AZ31 showed pronounced susceptibility to filiform corrosion.

Texture, Microstructure and Strain Sensibility in Compressed Magnesium Alloys

2005 ◽  
Vol 488-489 ◽  
pp. 185-188 ◽  
Author(s):  
Ping Yang ◽  
Zude Zhao ◽  
Li Meng ◽  
Xueping Ren ◽  
Shao Dong Huang
Keyword(s):  
Plane Strain ◽  
Magnesium Alloys ◽  
Deformation Process ◽  
Az31 Alloy ◽  
Deformation Mechanisms ◽  
Strain Condition ◽  
Zk60 Alloy ◽  
Initial Texture ◽  
Kinetics Of ◽  
External Strain

Depending on its initial texture and external strain condition differences in deformation mechanisms, kinetics of dynamic recrystallization or even superplastic behaviors may emerge in magnesium alloys leading to distinct microstructure and texture evolutions. When imposed strain condition is altered, e.g. from plane strain compression to rolling or uniaxial compression, the deformation anisotropy will decrease in different rates and basal slip and {1012} twinning will dominate deformation process. This work examines this strain sensibility by inspecting the σ-ε curves, microstructures and textures in a quasi plane-strain compressed ZK60 alloy and compares the results with those of AZ31 alloy compressed in channel die.

scholarly journals Corrosion Resistance of Steel Pipelines under Various Thermal Insulation Materials

2021 ◽  
Vol 2(50) ◽  
Author(s):  
Anatoly Zemlyanko ◽  
◽  
Vyacheslav Semenov ◽  
Aleksey Zhukov ◽  
Elena Shuvalova ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Open Porosity ◽  
Residual Life ◽  
Experimental Studies ◽  
Corrosion Damage ◽  
Corrosion Process ◽  
Water Soluble ◽  
Insulating Materials ◽  
Remaining Service Life ◽  
Insulation Systems

The durability of insulation systems for pipelines is determined by the operational resistance of the pipeline material and the design of the insulation system. The issue of studying the corrosion processes of steel pipelines under various heat-insulating materials is relevant. The aim of the work was to study the process of corrosion of steel pipelines under insulating materials of vari-ous nature and porosity. The object of research is pipeline insulation systems. The subject of research is the corrosion processes in various insulation systems. This goal was achieved by car-rying out a set of experimental studies aimed at studying the rate of the corrosion process of the metal of the pipeline, insulated with various materials, with the subsequent calculation of the remaining service life of the pipeline. The most significant results are: the dependence of the corrosion rate and the area of damage of carbon steel on the structure (porosity) of the heat-insulating material, the residual number of ions of water-soluble chlorides. It was found that the maximum corrosion rate of steel under materials with open porosity is 0.29-0.41 mm/year. The increase in the rate of the corrosion process is directly proportional to the increase in the number of chlorine anions in the structure of the material. The smallest area of corrosion damage to the steel surface is observed under materials with open porosity. The significance of the results ob-tained consists in determining the residual life of the pipeline under a heat-insulating layer of various materials.

Fruit wrapping kraft coated paper promotes the isolation of actinobacteria using ex situ and in situ methods

2021 ◽  
Author(s):  
Faezeh Almasi ◽  
Maghsoud Kafshnouchi ◽  
Fatemeh Mohammadipanah ◽  
Javad Hamedi
Keyword(s):  
Ex Situ ◽  
Coated Paper ◽  
In Situ Methods

The synthesis of Ru/CNF colloidal catalysts: Comparison of ex-situ and in-situ methods

2017 ◽  
Vol 4 (11) ◽  
pp. 11364-11370 ◽  
Author(s):  
Yuliya S. Demidova ◽  
Irina L. Simakova ◽  
Tim Schubert ◽  
Dmitry Yu. Murzin
Keyword(s):  
Ex Situ ◽  
In Situ Methods

scholarly journals Conservation of Rare Plants Using “Ex Situ“ And ”In Situ” Methods in Coal Industry Objects Designing

2018 ◽  
Vol 41 ◽  
pp. 02009
Author(s):  
Oleg Kupriyanov ◽  
Tatyana Strelnikova
Keyword(s):  
Natural Habitat ◽  
Botanical Garden ◽  
Coal Industry ◽  
Rare Plants ◽  
Ex Situ ◽  
Open Pit ◽  
Plant Populations ◽  
Industrial Enterprises ◽  
In Situ Methods

The experience of predesign inspection of the territory put under impact of future open pit is observed in the article. Geobotanical researches were carried out and populations of two plant species included in the Red Book of the Kemerovo region were found: Glycyrrhiza uralensis Fischer and Epipactis helleborine (L.) Grantz. Conservation of G. uralensis was carried out by “in situ” method – by transfer on other natural habitat. Individuals of E. helleborine were transferred at the territory of the Kuzbass botanical garden. Two years' observations of populations’ condition have shown successful growth of all individuals. These methods of conservation of rare plant populations are recommended by Project of UNDP-GEF for implementation at the industrial enterprises.

scholarly journals Inclusion removal and grain refinement of magnesium alloy castings

2021 ◽  
Author(s):  
Abdallah Elsayed
Keyword(s):  
Magnesium Alloy ◽  
Neutron Diffraction ◽  
Grain Refinement ◽  
Magnesium Alloys ◽  
Ex Situ ◽  
Inclusion Removal ◽  
Carbon Inoculation ◽  
Aluminum Silicon Carbide ◽  
In Situ Neutron Diffraction

Magnesium alloys show promise to be materials for lightweighting of automotive and aerospace vehicles improving fuel efficiencies and vehicle performance. A majority of magnesium alloy components are produced using casting where susceptibility to forming inclusions and coarse grain sizes could result. Development of effective inclusion removal techniques and better understanding of grain refinement of magnesium alloys could help in improving their mechanical properties to advance them to more structurally demanding applications. This research aimed to develop an environmentally friendly alternative to the grain refinement and inclusion removal capabilities of carbon based hexachloroethane as it releases dioxins, chlorine gas and corrodes foundry equipment. A secondary aim was to pioneer in-situ neutron diffraction to examine the solidification of magnesium alloys. The research involved preparing tensile samples of AZ91E magnesium alloy using permanent mould casting. Inclusion removal was conducted by using filtration and argon gas bubbling. Castings grain refined using hexachloroethane (0.25, 0.50 and 0.75 wt.%) were compared against ex-situ aluminum-silicon carbide and in-situ aluminum-carbon based grain refiners combined with filtration and argon gas bubbling. Further, in-situ neutron diffraction was utilized for phase analysis and fraction solid determination of magnesium-zinc and magnesium-aluminum alloys. There was a significant improvement in yield strength, ultimate tensile strength and elongation with filtration plus argon bubbling, carbon inoculation or both filtration plus argon bubbling and carbon inoculation. The results indicated that the mechanism of the observed ~20% reduction in grain sizes with carbon inoculation (hexachloroethane, ex-situ aluminum-silicon carbide and in-situ aluminum-carbon) was explained through duplex nucleation of Mn-Al and Al-Mg-C-O (likely Al2MgC2) phases. Finally, in-situ neutron diffraction was used to follow the formation of Mg17Al12 eutectic phase in a magnesium-9 wt.% aluminum alloy. For the magnesium-zinc alloys, in-situ neutron diffraction enabled characterization of the effects of zirconium to the fraction solid growth of (1010), (0002) and (1011) α-Mg planes. The societal and environmental impact of this research is significant. There is a clear demonstration of alternatives to the universally used hexachloroethane grain refiner promoting harmful emissions. Improved mechanical properties resulting from new grain refinement and iv inclusion filtration are a major advancement in promoting weight reduction, improved castability and decreased environmental impact for automotive and aerospace industries.

Ex Situ and In Situ Methods for Complete Oxygen and Non-Carbidic Carbon Removal from (0001)SI 6H-SiC Surfaces

1996 ◽  
Vol 423 ◽  
Author(s):  
Sean W. King ◽  
Mark C. Benjamin ◽  
Richard S. Kern ◽  
Robert J. Nemanich ◽  
Robert F. Davis
Keyword(s):  
Ex Situ ◽  
Carbon Removal ◽  
Capping Layer ◽  
In Situ Methods ◽  
Acids And Bases

AbstractComparisons between the wetting characteristics of (0001)si 6H-SiC and (111) Si surfaces in various acids and bases were made. It was found that 10:1 HF dipped Si (111) surfaces were hydrophobic where as the (0001)si 6H-SiC surfaces were hydrophilic. (0001)si 6H-SiC surfaces capped with a 20Å Si layer, however, were hydrophobic after HF dipping and exhibited outgassing levels on annealing which were several orders of magnitude lower than SiC wafers dipped in HF without the capping layer. Annealing the Si capped (0001)si 6H-SiC surfaces in UHV at 1100°C for 5 min. was found to be sufficient to thermally desorb the Si capping layer and produce a (3×3) Si rich, oxygen free (0001)si 6H-SiC surface.

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