scholarly journals Study of the Thermochemical Surface Treatment Effect on the Phase Precipitation and Degradation Behaviour of DSS and SDSS

Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 165 ◽  
Author(s):  
Alisiya Biserova-Tahchieva ◽  
Jose Maria Cabrera ◽  
Nuria Llorca-Isern
Keyword(s):  
Corrosion Behaviour ◽  
General Corrosion ◽  
Secondary Phases ◽  
Phase Precipitation ◽  
Degradation Behaviour ◽  
Surface Protection ◽  
Thermochemical Process ◽  
Long Time ◽  
Plasma Carburizing ◽  
Carburizing Process

In this study, the effect of a plasma ion carburizing process to duplex and superduplex stainless steels (DSS and SDSS), at 925 °C for a long time, as thermochemical process influencing the microstructural evolution is presented. The objective is to analyse the diffusion elements’ influence on the precipitation of secondary phases after additional short thermal treatment. A comparison among the different treatments was performed after the resulting microstructures were analysed by Field Emission—Scanning Electron Microscope. Precipitation of secondary phases—sigma (σ), chi (χ), nitrides and carbides—seemed to occur during the treatments in a similar way for both steels (DSS and SDSS), although they showed a different morphology and precipitation mode. General corrosion behaviour of untreated and treated samples was investigated by potentiodynamic tests in order to prove their corrosion resistance. It was found that an improvement of the surface protection after the plasma carburizing process occurred.

Degradation Behaviour of Metallic Biomaterials for Degradable Stents

2006 ◽  
Vol 15-17 ◽  
pp. 113-118 ◽  
Author(s):  
Hendra Hermawan ◽  
Maryam Moravej ◽  
Dominique Dubé ◽  
Michel Fiset ◽  
D. Mantovani
Keyword(s):  
Potentiodynamic Polarization ◽  
Degradation Rate ◽  
Corrosion Behaviour ◽  
Dynamic Test ◽  
Potential Candidate ◽  
Human Coronary Artery ◽  
Ion Release ◽  
Degradation Behaviour ◽  
Static Immersion

The short-term need of scaffolding function of stent and the prevention of potential longterm complication of permanently implanted stent have directed to the original idea of biodegradable stent. Selecting and developing materials showing appropriate mechanical and degradation properties are key steps for the development of this new class of medical devices. Therefore, the study of their in vitro degradation behaviour is mandatory for the selection of potential candidate materials suited in vivo. In this work, the degradation behaviour of current studied biodegradable metals including three magnesium alloys (Mg, AM60B and AZ91D), pure iron and Fe-35Mn was investigated. The tests were performed in a simulated blood plasma solution at 37±0.1 oC, using three different methods; potentiodynamic polarization, static immersion, and dynamic test in a test-bench which mimics the flow condition in human coronary artery. Degradation rate was determined as ion release rate measured by using atomic adsorption spectroscopy (AAS) and also estimated from weight loss and corrosion current. Surface morphology and chemical composition of corroded specimens were analyzed by using SEM/EDS. The three degradation methods provide consistent results in corrosion tendency, where Mg showed the highest corrosion rate followed by AZ91D, AM60B, Fe-35Mn and iron. Potentiodynamic polarization gives a rapid estimation of corrosion behaviour and rate. Static immersion test shows the effect of time on the degradation rate and behaviour. Dynamic test provides the closest approach to the environment after stent implantation and its results show the effect of the flow on the materials degradation. In conclusion, the three investigated methods can be applied for screening, selecting and validating materials for degradable stent application before going further to in vivo assessments.

scholarly journals Study on Upgradation in Carburizing Technologies for steel strength

2019 ◽  
pp. 78-84
Keyword(s):  
Surface Hardness ◽  
Carbon Diffusion ◽  
Lower Surface ◽  
Diffusion Controlled ◽  
Steel Strength ◽  
Carbon Transfer ◽  
Gas Carburizing ◽  
Kinetics Of ◽  
Plasma Carburizing ◽  
Carburizing Process

Carburizing technologies are used to provide strength on low quality metals. This technology is being developing with novel improvements significantly. The carburizing process consists of, first releasing Carbon mono-oxide from charcoal material and then transfers carbon to raw metal. There are favorable upgradation in these technologies from researchers which have a paramount industrial importance. In Vacuum gas carburizing, the steel metal is carburized with (Acetylene and Propane) gases. These gases are at low pressure and high temperature. The results show that the metal is 1.5 times harder than its raw form. There are also used mathematical models to validate the results. It used gas and solid phases for validation. In pulse carburizing, carbon diffusion on steel is investigated with heat treatment. This process includes several carburizing stages. This process is based on Darken bi velocity and drift velocity. It accounts to demonstrate the kinetics of carbon transfer on steel surface. This design is very useful by regarding carburizing time for this process design. In Plasma carburizing, the mixtures of gases are used to harden the steel. The carburizing temperature was varied in cementite and martensitic. The favorable results show that these specimens have (Lower surface roughness, higher surface hardness and Low wear rate). It is a most novel diffusion controlled novel process till the present time. The carburized metal is used in industry by including (Turbine gears and Air craft engine). Henceforth, It is of great importance to study the carburizing technologies for providing better strength on metal.

Pulsed Eddy Current Response to General Corrosion in Concrete Rebar

2020 ◽  
Vol 3 (4) ◽  
Author(s):  
Ian Eddy ◽  
P. R. Underhill ◽  
J. Morelli ◽  
T. W. Krause
Keyword(s):  
Transient Response ◽  
Exponential Decay ◽  
Eddy Current ◽  
Structural Integrity ◽  
Concrete Structures ◽  
Highway Bridges ◽  
General Corrosion ◽  
Current Response ◽  
Pulsed Eddy Current ◽  
Long Time

Abstract Corrosion of carbon steel rebar in concrete structures, such as highway bridges and buildings, has a direct impact on their structural integrity since the rebar provides the tensile strength within the structure. Rebar strength depends on the remaining effective radius of a given rod. Long-time decay up to 0.1 s, in the transient response of pulsed eddy current (PEC), was examined as a potential method to quantify general corrosion in ferromagnetic rebar. The transient response of a coaxial solenoidal drive–receive coil pair, oriented parallel to the rebar axis, was analyzed over a range of distances into the concrete (liftoff) and rebar radii. At long times, the single exponential decay constant was largely independent of liftoff. A power law relationship for the characteristic decay time, consistent with long-time diffusion of electromagnetic fields into a rod, was observed. The intercept of a best-fit line to measured voltage decay decreased exponentially with liftoff and maintained a measurable response up to 110 mm distance for a 25 mm (1 in.) diameter rebar. This exponential decay was present in 22 mm (7/8 in.), 19 mm (3/4 in.), and 15 mm (5/8 in.) samples as well. Reported results demonstrate the potential for PEC to quantify remaining cross-sectional area of rebar in concrete structures.

scholarly journals On the Application of Bipolar Electrochemistry to Characterise the Localised Corrosion Behaviour of Type 420 Ferritic Stainless Steel

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 794 ◽  
Author(s):  
Yiqi Zhou ◽  
Dirk Lars Engelberg
Keyword(s):  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Pitting Corrosion ◽  
Corrosion Behaviour ◽  
General Corrosion ◽  
Full Spectrum ◽  
Nucleation Sites ◽  
Corrosion Pitting ◽  
Cathodic Region ◽  
Bipolar Electrochemistry

Bipolar electrochemistry has been applied to Type 420 ferritic stainless steel in order to determine the full spectrum of anodic-to-cathodic polarisation behaviour. The occurrence of crevice corrosion, pitting corrosion in combination with general corrosion, pitting corrosion only, general corrosion only, followed by a cathodic region has been observed. Instances of pitting corrosion initiated near chromium-rich carbides with Cr23C6, Cr3C2, and Cr7C3 identified as pit nucleation sites. The observed pit growth kinetics were independent of the electrochemical over-potential. Characterisation of the pit size distributions supports the presence of a critical dissolved volume for the transition of metastable to stable pit growth and pit coalescence.

Weight Gain and Hydrogen Absorption in Supercritical Water At 500°C of Chromium-Coated Zirconium-Based Alloys: Transverse vs Longitudinal Direction

2021 ◽  
Author(s):  
Kittima Khumsa-Ang ◽  
Stephane Rousseau ◽  
Oksana Shiman
Keyword(s):  
Weight Gain ◽  
Supercritical Water ◽  
Hydrogen Absorption ◽  
Corrosion Behaviour ◽  
Reactor Core ◽  
Neutron Cross Section ◽  
Zirconium Alloys ◽  
Longitudinal Direction ◽  
General Corrosion ◽  
Enriched Uranium

Abstract Canadian Nuclear Laboratories (CNL) has an on-going Research & Development programme to support the development of a scaled-down 300 MWe version of the Canadian Super-Critical Water Reactor (SCWR) concept. The 300 MWe and 170-channel reactor core concept uses low enriched uranium fuel and features a maximum cladding temperature of 500°C. Our goal is to test surfacemodified zirconium alloys for use as fuel cladding. Zirconium alloys are attractive as they offer low neutron cross section thereby allowing the use of low enriched fuel. In this paper, we report on the results of general corrosion experiments used to evaluate chromiumcoated zirconium-based alloys in the two chemistries (630 ug/kg O2 in both deaerated and lithiated supercritical water). These experiments were conducted in a refreshed autoclave at 500°C and 23.5 MPa. After exposure, the weight gain and the hydrogen absorption were examined. At adequate coating thickness, longitudinal and transverse coupons show similar corrosion behaviour with improved corrosion resistance compared to uncoated coupons. The measured concentrations of hydrogen absorption are higher for the transverse coupons. Alkaline treatment resulted in higher weight gains than was found in pure oxygenated supercritical water.

Pengaruh Substitusi Ion Mn dan Ion Co Serta Ion Ti pada Pembentukan Fasa dan Sifat Magnetik Barium Hexaferrite BaFe9(MnCo)1,5Ti1,5O19 Disintesis Melalui Rute Metallurgi Serbuk

2013 ◽  
Vol 3 (01) ◽  
pp. 79
Author(s):  
Priyono P ◽  
Eddy Siradj ◽  
Azwar Manaf
Keyword(s):  
Applied Field ◽  
High Performance ◽  
Room Temperature ◽  
Barium Hexaferrite ◽  
Lattice Parameter ◽  
Partial Substitution ◽  
Powder Metallurgy Method ◽  
Secondary Phases ◽  
X Ray ◽  
Long Time

<span>Barium ferrite with hexagonal molecular BaFe<span>12<span>O<span>19 <span>is well-known for its high performance <span>permanent magnetic and good mechanical properties and attracted attention of researchers for <span>a long time. The hexaferrite powders were produced according to a conventional ceramic <span>process with powder metallurgy method. Moreover, the powders were analyzed by X-ray <span>diffraction, to detect the presence of secondary phases. The magnetic properties of the samples<br /><span>were measured at room temperature using Permeagraph with a maximum applied field of 1.5 <span>T. The calculation of the lattice parameter on conventional magnets (BaFe<span>12<span>O<span>19<span>) results a = b = <span>5,894 Å and c = 23,210 Å, while the substituted phase has a range value of a = b between <span>5,893 Å to 5,899 Å, and c lattice parameter value is in the range of 23,328 ˚A to 23,346 Å.<br /><span>With the partial substitution of Fe<span>+3 <span>ions by Mn<span>+2 <span>ions, ion Co<span>+2 <span>and Ti<span>+4 <span>ion magnetic <span>properties decrease primarily on the magnetic coercivity from 125 kA / m (conventional) to ~ 5 <span>kA /m in the substituted materials.</span></span></span></span></span></span></span></span></span></span></span><br /></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>

In-Situ Corrosion Studies on Cast Steel for a High-Level Waste Packaging in a Rock Salt Repository

1988 ◽  
Vol 127 ◽  
Author(s):  
W. Schwarzkopf ◽  
E. Smailos ◽  
R. Koster
Keyword(s):  
Electron Beam ◽  
Rock Salt ◽  
Corrosion Behaviour ◽  
Cast Steel ◽  
Maximum Temperature ◽  
High Level Waste ◽  
General Corrosion ◽  
Vertical Temperature Profile ◽  
Corrosion Studies

ABSTRACTPrevious corrosion studies performed on a number of materials have shown that unalloyed steels are promising materials for long-term resistant packagings to be used in disposal of heat-generating wastes in rock salt formations. This is the reason why those steels are the subject of more detailed investigations. This paper reports an in-situ experiment conducted in the Asse salt mine in which the influence of selected characteristics (welding, shape) of containers on the corrosion behaviour of cast steel was studied. The material was tested in NaCl brine which might intrude into an HLW borehole in an accident scenario. For this, an electron beam welded cast-steel tube was stored for 18 months in a 2-m deep heated borehole and the annular gap between the tube and the borehole wall was filled with saturated NaCl brine. The vertical temperature profile in the borehole was in the range from 90°C to 200°C; the maximum temperature occurred in the center of the heated zone and the minimum temperature in the upper parts of tube.Under the testing conditions cast steel was subjected to general corrosion at a maximum corrosion rate of 120 μm/a. Considering this magnitude of the corrosion rates, the resulting corrosion allowances are technically acceptable for a packaging having long service-lives. Pitting and crevice corrosion as well as stress-corrosion cracking did not occur in cast steel, and electron beam welding did not exert a noticeable influence on cast-steel corrosion. With these results available, cast steel continues to be considered as a promising HLW packaging material.

Mg–1Zn–1Ca alloy for biomedical applications. Influence of the secondary phases on the mechanical and corrosion behaviour

2020 ◽  
Vol 831 ◽  
pp. 154735 ◽  
Author(s):  
N. Pulido-González ◽  
B. Torres ◽  
S. García-Rodríguez ◽  
P. Rodrigo ◽  
V. Bonache ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Corrosion Behaviour ◽  
Secondary Phases

Intergranular and general Corrosion behaviour of 17-4 PH weldments

1995 ◽  
Vol 46 (9) ◽  
pp. 534-538 ◽  
Author(s):  
K. S. Raja ◽  
K. Prasad Rao
Keyword(s):  
Corrosion Behaviour ◽  
General Corrosion

Influence of Microstructural Constituents and Applied Thermomechanical Processes on Corrosion Behaviour of Aluminum Alloys Produced with Twin Roll Casting (TRC) Technique

2014 ◽  
Vol 794-796 ◽  
pp. 181-186 ◽  
Author(s):  
Cemil Işıksaçan ◽  
Mert Günyüz ◽  
Onur Birbaşar ◽  
Cengiz Konya ◽  
Murat Dündar
Keyword(s):  
Free Surface ◽  
Aluminum Alloys ◽  
Corrosion Behaviour ◽  
Corrosion Mechanism ◽  
General Corrosion ◽  
Corrosion Performance ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Thermomechanical Processes ◽  
Twin Roll

Aluminum alloys produced with Twin Roll Casting (TRC) technology still necessitate to be thoroughly investigated in some areas. Corrosion mechanisms operating under special conditions with the contribution of unique features of the microstructure are among those. Materials produced with TRC have unique features inherently generated due to the solidification path of the material during casting. Contrary to the very fine particles at the locations close to the free surface, centerline segregation (CLS) occurring at the mid-plane of the thickness have different morphological and compositional features than rest of the microstructure. While, unless directly exposed, it has almost no contribution to the general corrosion behavior of the alloy, some manufacturing processes generation new free surfaces in the material for CLS to be exposed to the corrosive media can be harmful for overall general corrosion performance of the alloy. It differentiates itself in corrosion behaviour with its compositional and morphological features than rest of the microstructure. Hence, influence of CLS on corrosion behaviour of two different alloys in 3000 and 8000 series employed for heat exchangers and packaging applications, respectively, are studied in the present study. Since CLS does not disappear with rolling passes but only changes its morphology, samples were taken at appropriate thickness of the downstream process that allow corrosion tests to be conducted at the cross section of the samples. Metallographical preparation techniques were used to reveal the CLS. Samples were dipped in to the HCl-NaCl containing test solution to observe the progress of corrosion in the matrix and heavily populated CLS areas during the course of test. Open-circuit potential (OCP) measurements were carried out on the rolled free surface, quarter plane and mid plane of the samples after milling the surface of the samples. Different samples produced with compositional and thermomechanical processing route variants were used. Results show that composition of the alloy and applied thermomechanical processes influence the corrosion characteristics of CLS and accordingly the overall corrosion performance. Other important finding is the contribution of manufacturing method to corrosion mechanism whether if it reveals the CLS by creating new free cross sectional surfaces.

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