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1

Vascular corrosion casting of human heart  

Directory of Open Access Journals (Sweden)

Full Text Available Variation in the morphological pattern of coronary arteries and their major branches is an important factor in the assessment and treatment of coronary heart disease. Detailed knowledge of the blood supply of the heart is necessary today because of the wider practice of cardiac surgery, and also for better understanding of the anomalous branches, anastomosis and dominance pattern in circulation caused by coronary vasculature. We utilized 80 human heart specimens and found right dominance in 69 specimens, left dominance in 9 specimens and balanced type of circulation in 2 specimens. We observed anastomosis between the major arteries in arteriogram but in vascular corrosion method we did not found because cast substance interpretation to minor vessels is too difficult. The present study acknowledges about Coronary vascular pattern, circulatory dominance of the arteries and by using the vascular corrosion method. [Int J Res Med Sci 2013; 1(3.000: 237-239

J. Vasudeva Reddy

2013-06-01

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Vascular corrosion casting: analyzing wall shear stress in the portal vein and vascular abnormalities in portal hypertensive and cirrhotic rodents.  

Science.gov (United States)

Vascular corrosion casting is an established method of anatomical preparation that has recently been revived and has proven to be an excellent tool for detailed three-dimensional (3D) morphological examination of normal and pathological microcirculation. In addition, the geometry provided by vascular casts can be further used to calculate wall shear stress (WSS) in a vascular bed using computational techniques. In the first part of this study, the microvascular morphological changes associated with portal hypertension (PHT) and cirrhosis in vascular casts are described. The second part of this study consists of a quantitative analysis of the WSS in the portal vein in casts of different animal models of PHT and cirrhosis using computational fluid dynamics (CFD). Microvascular changes in the splanchnic, hepatic and pulmonary territory of portal hypertensive and cirrhotic mice are described in detail with stereomicroscopic examination and scanning electron microscopy. To our knowledge, our results are the first to report the vascular changes in the common bile duct ligation cirrhotic model. Calculating WSS using CFD methods is a feasible technique in PHT and cirrhosis, enabling the differentiation between different animal models. First, a dimensional analysis was performed, followed by a CFD calculation describing the spatial and temporal WSS distributions in the portal vein. WSS was significantly different between sham/cirrhotic/pure PHT animals with the highest values in the latter. Up till now, no techniques have been developed to quantify WSS in the portal vein in laboratory animals. This study showed for the first time that vascular casting has an important role not only in the morphological evaluation of animal models of PHT and cirrhosis, but also in defining the biological response of the portal vein wall to hemodynamic changes. CFD in 3D geometries can be used to describe the spatial and temporal variations in WSS in the portal vein and to better understand the forces affecting mechanotransduction in the endothelium. PMID:20714322

Van Steenkiste, Christophe; Trachet, Bram; Casteleyn, Christophe; van Loo, Denis; Van Hoorebeke, Luc; Segers, Patrick; Geerts, Anja; Van Vlierberghe, Hans; Colle, Isabelle

2010-11-01

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Microvascular system of the rat incisor enamel organ. A scanning electron microscopic study of vascular corrosion casts.  

Science.gov (United States)

The rat incisor is a commonly used model in studies of tooth eruption, amelogenesis and effects of mechanical loading on the dental and periodontal tissues. The purpose of this study was to assess the three-dimensional architecture of the microvascular bed of the rat incisor enamel organ, to describe the direction of blood flow, and to provide a histometric assessment of the vascular categories that can be statistically analyzed. Vascular corrosion casts were prepared and examined by scanning electron microscopy. The microvasculature of the labial periodontal space was arranged in three distinct layers. The inner layer in direct relation to the enamel organ consisted of a capillary network which was drained by short venules at the cemento-enamel junction. The intermediate layer consisted of arterioles oriented parallel to the long axis of the incisor mainly mid-labially, branching off smaller arterioles to the capillary network. The outer layer was formed by flattened sinusoid vessels of larger caliber. Blood supply was from the anterior superior alveolar artery branches through the arterioles into the capillary network. Drainage was postero-laterally along the cemento-enamel junction via short venules which emptied into the sinusoid vessels, finally to flow through Volkmann's canals into the alveolar bone via small venules. The findings demonstrate that the microvasculature of the rat incisor enamel organ has an exceptionally high level of physiologically-adapted structural organization. PMID:9879913

El-Agroudi, M A; Selliseth, N J; Selvig, K A

1998-12-01

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Vascularization of the brains of the Atlantic and Pacific hagfishes, Myxine glutinosa and Eptatretus stouti: a scanning electron microscope study of vascular corrosion casts.  

Science.gov (United States)

The microvascularization of the brains of the hagfishes, Myxine glutinosa L. and Eptatretus stouti, were studied by scanning electron microscopy (SEM) of microvascular corrosion casts. Sections of these casts were used to determine the vascular territories of defined brain areas. Histological serial sections (10 microm) of the brains served for correlation of findings. Analysis of the microvascular casts of both species revealed that the blood supply to and from these brains arose ventrally and dorsally, respectively. Neither species possesses an arterial circle (Circulus Willisi) and both have similar microvascular patterns. The only difference between Myxine and Eptatretus was that the posterior cerebral artery in Myxine divides into mesencephalic and rhombencephalic branches, and in Eptatretus a third branch, termed telencephalic branch, arises from the posterior cerebral artery. 3D-morphometry revealed that luminal diameters of: 1) intracerebral arteries and arterioles range from 35.11 +/- 5.66 microm (mean +/- SEM) in the hypothalamus to 92.69 +/- 14.48 microm in the thalamus; 2) capillaries range from 17.8 +/- 0.44 microm in the olfactory bulb to 21.70 +/- 0.87 microm in the basal ganglia; and 3) intracerebral venules and veins range from 49.38 +/- 4.17 microm in the hypothalamus to 75.58 +/- 6.59 microm in the rhombencephalon. Interbranching distances of arteries and arterioles range from 179.19 +/- 11.32 microm in the optic tectum to 235.19 +/- 94.64 microm in the hypothalamus. Capillaries range from 91.07 +/- 6.22 microm in the hypothalamus to 116.15 +/- 9.45 microm in the thalamus, and venules and veins range from 137.30 +/- 18.11 microm in the hypothalamus to 189.83 +/- 17.47 microm in the optic tectum. Intervascular distances range from 70.58 +/- 3.58 microm in the olfactory bulb to 89.52 +/- 5.74 microm in the optic tectum. Branching angles of arteries and arterioles range from 38.39 +/- 10.9 degrees in the olfactory bulb to 100.73 +/- 9.4 degrees in the optic tectum, and the branching angles of capillaries range from 74.40 +/- 5.42 degrees in the optic tectum to 90.24 +/- 4.66 degrees in the olfactory bulb. Finally, the branching angles of the venules and veins range from 67.84 +/- 6.83 degrees in the tegmentum of the mesencephalon to 92.30 +/- 6.35 degrees in the optic tectum. PMID:11981804

Cecon, Stephan; Minnich, Bernd; Lametschwandtner, Alois

2002-07-01

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Microangioarchitecture of the guinea pig gallbladder and bile duct as studied by scanning electron microscopy of vascular corrosion casts.  

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The microvasculature of the gallbladder, the common bile duct, and the duodenal papilla was investigated in 20 albino guinea pigs (Cavia porcellus) using microvascular corrosion casting and scanning electron microscopy (SEM). Main supplying and draining vessels (first-order vessels) approach the gallbladder along the cystic duct. From the latter, penetrating vessels (second-order vessels) arise which pierce the muscular coat of the gallbladder body to form the plexus of third-order vessels be...

Aharinejad, S.; Lametschwandtner, A.

1992-01-01

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Characterization of the vasa vasorum in the human great saphenous vein: a scanning electron microscopy and 3D-morphometry study using vascular corrosion casts.  

Science.gov (United States)

The vasa vasorum (VV) of explanted segments of the human great saphenous vein (Vena saphena magna; HGSV), harvested during dissection for coronary bypass grafts or diseased vein segments from the "Salzburger Landesklinikum," were studied by scanning electron microscopy and three-dimensional morphometry of microvascular corrosion casts. The main objective of this study was to examine the VV's structural arrangement in order to find the most vital segments of the HGSV and in turn to improve the results of coronary bypass surgeries. The study presents a meticulous analysis of the whole microvascular system of the VV of the HGSV and its three-dimensional arrangement. It is one of the first studies yielding detailed quantitative data on geometry of the VV of the HGSV. A detailed insight into different vascular parameters such as vessel diameter, interbranching, intervascular distances, and branching angles at different levels of the VV's angioarchitecture and in different parts of the HGSV in health and disease is given. Further, the geometry of bifurcations was examined in order to compute the physiological optimality principles of this delicate vascular system based on its construction, maintenance, and function. PMID:24913662

Herbst, Markus; Hölzenbein, Thomas Joachim; Minnich, Bernd

2014-08-01

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Corrosion Studies of Wrought and Cast NASA-23 Alloy  

Science.gov (United States)

Corrosion studies were carried out for wrought and cast NASA-23 alloy using electrochemical methods. The scanning reference electrode technique (SRET), the polarization resistance technique (PR), and the electrochemical impedance spectroscopy (EIS) were employed. These studies corroborate the findings of stress corrosion studies performed earlier, in that the material is highly resistant to corrosion.

Danford, M. D.

1997-01-01

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Wear-corrosion study of white cast irons  

Energy Technology Data Exchange (ETDEWEB)

A US Bureau of Mines study to quantify synergism between wear and corrosion of white cast iron in an aqueous sulfate environment was conducted using a rotating cylinder-anvil apparatus. A commercial 13.5% Cr white cast iron sample and the individual constituents of a white cast iron were studied to determine the role of each phase in the degradation processes of wear, corrosion and wear-corrosion synergism. These constituent phases consisting of matrix (13%Cr-87%Fe), Cr-depleted matrix (5%Cr-95%Fe) two M{sub 7}C{sub 3}`s and two M{sub 3}C (where M=Fe,Cr) were fabricated by powder metallurgy. The wear-corrosion studies consisted of four tests: the potentiodynamic polarization tests with and without anvil pressure and wear tests with and without cathodic protection. The force on the anvils was 28 kg and the rotation speed of the approximately 2.5 cm diameter samples was 5.24 (rad s{sup -1}) with peripheral velocity of 0.0654 m s{sup -1}. Even though corrosion alone was a small percentage of the total degradation, representing as little as 0.1% of the total degradation, the wear-corrosion synergism contribution was significant, accounting for as much as 91% of the total degradation. (orig.)

Watson, S.W. [US Bureau of Mines, Albany Research Center, OR (United States); Madsen, B.W. [US Bureau of Mines, Albany Research Center, OR (United States); Cramer, S.D. [US Bureau of Mines, Albany Research Center, OR (United States)

1995-03-01

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Corrosion fatigue of cast aluminium- and cast magnesium alloys; Korrosionsermuedung von Aluminium- und Magnesium-Gusslegierungen  

Energy Technology Data Exchange (ETDEWEB)

The fatigue properties of the aluminium cast alloys AlSi7Mg and AlSi10Mg, magnesium high pressure die-cast AZ91 hp and AM60 hp, as well as low-pressure permanent mould casting AZ91 hp were determined at numbers of cycles to failure between 10{sup 5} and 10{sup 9} in ambient air and in saltwater spray. The investigations were performed at constant amplitudes and in addition at varying load amplitudes for aluminium cast alloy AlSi10Mg and low-pressure permanent mould casting AZ91 hp with a high-frequency testing facility (20 kHz ultrasound). The SN-curves of the aluminium cast alloys and of the magnesium low-pressure permanent mould casting are steeper in corrosive environment than in laboratory air. No endurance limit could be detected up to 10{sup 9} cycles in both environments. The magnesium high pressure die-cast alloys do not have an endurance limit in saltwater spray, whereas an endurance limit could be detected in laboratory air. The life time curves for in-service loading conditions are about parallel to the SN-curves for ambient air, but steeper for corrosive environment. The reason for the reduced fatigue properties in corrosive environment are accelerated crack initiation and higher crack propagation rates. Material defects may lead to a large scatter of the fatigue data for testing in air as well as in saltwater spray. Corrosion pits are formed on the surface of both light-weight alloys at higher number of cycles. They become crack initiation sites. (orig.) 10 refs.

Mayer, H.; Papakyriacou, M.; Stanzl-Tschegg, S.; Zettl, B. [Univ. fuer Bodenkultur, Vienna (Austria). Inst. fuer Meteorol. und Phys.; Tschegg, E. [Technische Univ., Vienna (Austria). Inst. fuer Angewandte und Technische Physik; Lipowsky, H.; Roesch, R.; Stich, A. [Audi AG, Ingolstadt (Germany)

1999-02-01

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Stress Corrosion Cracking Behavior of Cast Stainless Steels  

International Nuclear Information System (INIS)

Casting of austenitic stainless steels offers the possibility of directly producing large and/or relatively complex structures, such as the first wall shield modules or the diverter cassette for the ITER fusion reactor. Casting offers major cost savings when compared to fabrication via welding of quarter modules machined from large forgings. However, the strength properties of such cast components are typically considered inferior to those of conventionally forged and annealed components. To improve and validate cast stainless steel as a substitute for wrought stainless steel, a development and testing program was initiated, utilizing nitrogen and manganese additions to promote improved performance. This paper focuses on the response of the first set of developmental alloys to neutron-irradiation and susceptibility to stress corrosion cracking. These cast materials may also have applications for different components in light water reactors. Results showed that all steels exhibited irradiation-induced hardening and a corresponding drop in ductility, as expected, although there is still considerable ductility in the irradiated samples. The cast steels all exhibited reduced hardening in comparison to a wrought reference steels, which may be related to a larger grain size. Higher nitrogen contents did not negatively influence irradiation performance. Regarding stress corrosion cracking susceptibility, the large difference in grain size limits the comparison between wrough size limits the comparison between wrought and cast materials, and inclusions in a reference and archive cast alloy tests complicate analysis of these samples. Results suggest that the irradiated archive heat was more susceptible to cracking than the modified alloys, which may be related to the more complex microstructure. Further, the results suggest that the modified cast steel is at least as SCC resistant as wrought 316LN. The beneficial effect of nitrogen on the mechanical properties of the alloys remains after irradiation and is not detrimental to SCC resistance.

11

Corrosion resistant high silicon cast iron  

International Nuclear Information System (INIS)

Abstract: In domestic foundries production of acid resistance high silicon cast iron quite defined and because of that is with small productivity and many defect products. Process monitoring is with problems, because of that material is hard and brittle so sampling for characterisation is difficult, except of chemical analysis. That is reason for non destructive testing application, mainly ultrasonic. (Original)

12

Heat-transfer corrosion behaviour of cast Al alloy  

International Nuclear Information System (INIS)

Heat-transfer corrosion behaviour of an ISO 2379 cast Al alloy was studied in antifreeze radiator coolant under heat-rejecting condition. Extensive analyses of microstructures and corroded surfaces were carried out under the optical microscope, scanning electron microscope equipped with energy dispersive spectroscopy and X-ray diffractometer. Heat-rejecting condition led to a cavitation process and cavities were observed within the ?-Al matrix. Crevice corrosion was predominant at oxygen depleted regions in heat-transfer corrosion cell. Al2Cu, Al15(Fe,Mn)3Si2 dendrites, Al4Cu2Mg8Si7 and Si phases served as the effective cathodes resulting microgalvanic corrosion at the anodic site of ?-Al matrix

13

Corrosion evaluation of traditional and new bronzes for artistic castings  

International Nuclear Information System (INIS)

By electrochemical and accelerated weathering tests, the corrosion behaviour of a new type of tin-bronze, containing about 3 wt.% silicon (SI3 bronze) was compared to a traditional 5% Sn, 5% Zn, 5% Pb bronze used for artistic castings (G85 bronze) under conditions simulating urban-industrial and marine environments. The aggressive media were: a synthetic pH 3.1 acid rain (AR) solution; a typical moist SO2-NO x for a climatic chamber and AR or 3.5% NaCl aqueous solution for salt spray cabinet. In all the environments the corrosion product layers formed on SI3 bronze were more uniform and protective than those formed on the traditional G85 bronze. The nature and morphology of the corrosion products were investigated by X-ray diffraction (XRD), optical and scanning electron microscopy with microprobe (SEM-EDS), atomic force microscopy (AFM)

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Microvasculature of the dorsum of the rat tongue: a scanning electron microscopic study using corrosion casts.  

Science.gov (United States)

The purpose of this study was to examine the microvascular system of the dorsum of the rat tongue in relation to the subepithelial connective tissue relief. Methylmethacrylate corrosion casts of the vasculature as well as specimens in which the epithelium had been removed were prepared and examined by scanning electron microscopy (SEM). The SEM images revealed four distinct layers in the vasculature of the lamina propria. Superficially, Layer 1 comprised the irregularly shaped ends of capillary loops. Layer 2 consisted of parallel ascending and descending capillaries. These two layers were drained by the subjacent Layer 3, a fish-net-like venous plexus. More deeply, Layer 4 contained arterioles ascending from the muscular layers of the tongue. The vessels of larger papillary structures formed cylindric networks supplied by several arterioles and drained through a single venule to the venous plexus in Layer 3. At their base, the capillary loops often showed a constriction, suggestive of a sphincter. Arteriovenous anastomoses were rare. The epithelium-connective tissue interface showed short conical papillae as well as larger papillary structures which corresponded in both distribution and size to the capillary loops found in the vascular casts. The results confirm that the tongue is highly vascularized and demonstrate that the vascular supply to the papillae, taste buds, and other surface structures forms a highly organized and specific system which is adapted to the specific functions of this organ in the rat. PMID:8290883

Selliseth, N J; Selvig, K A

1993-12-01

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Corrosion of two kinds of cast steels containing chromium in hot concentrated alkaline  

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A typical hot concentrated alkaline corrosion environment exists in alumina metallurgical industry, so that steel materials with outstanding alkaline corrosion resistance are strongly demanded for its processing equipment. In this paper, the corrosion resistance of two kinds of martensitic cast steels containing chromium in static 303g/L NaOH alkaline solution at 85? was studied through polarization and potential-time curves, corrosion weight loss and corrosion morphology analysis. Experime...

Li, Wei; Liu, Jun-quan; Tu, Xiao-hui

2007-01-01

16

Corrosion behaviour of unalloyed steel and cast iron in groundwaters of the bedrock of Northern Switzerland  

International Nuclear Information System (INIS)

The corrosion behaviour of both materials is essentially the same in the two water compositions investigated. No significant effect of the bentonite on the corrosion behaviour could be detected. The corrosion rate decreases rapidly over the first 500 hours; after that time the corrosion rate settles to values difficult to determine accurately, but estimated to be less than 10 ?m/a both at 800C and 1400C. Localized attack was not observed. It is concluded that a corrosion allowance of 20 mm is adequate to ensure a life of 1'000 years for cast steel and cast iron under repository conditions close to the test conditions. (orig./PW)

17

Aqueous drainage paths in the equine eye: scanning electron microscopy of corrosion cast.  

Science.gov (United States)

The anterior vasculature of the pony eye was examined by the corrosion cast method. The anterior segment of the pony eye has a vascular pattern which is similar but distinct from that of other mammalian species. Large iridal veins collateralized directly with the anterior vortex venous system. The intrascleral plexus was present but formed a fine, radially oriented, extensive network. This contrasted to the circumferential larger-diameter intrascleral plexus noted in dogs and the canal of Schlemm present in primates. The intrascleral plexus only drained posteriorly in the pony as compared to that in other species where anterior collateralizations have been described. The pattern of aqueous outflow was found to have relevance clinically in veterinary medicine and could provide insight into the frequent occurrence and treatment of equine recurrent uveitis as well as diseases of the posterior segment. PMID:3199448

Smith, P; Samuelson, D; Brooks, D

1988-10-01

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Characteristics of low nickel ferritic-austenitic corrosion resistant cast steel  

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The article presents the results of microscopic examinations of corrosion resistant cast steel with reduced nickel content obtained in a test casting with varying wall thickness. Investigations were carried out in as-cast condition and after heat treatment. Regardless of the casting wall thickness, increasing the manganese and nitrogen content to about 5 % and 2 500 ppm, respectively, yields the material with a two-phase microstructure containing ferrite in an amount of 55,6 ÷ 57,2 % (magnet...

Kalandyk, B.; Zapa?a, R.; Sobula, S.; Go?rny, M.; Boron?, ?.

2014-01-01

19

Corrosion behaviour of powder metallurgical and cast Al-Zn-Mg base alloys  

International Nuclear Information System (INIS)

The behaviour of Al-Zn-Mg base alloys produced by powder metallurgy and casting has been studied using potentiodynamic polarisation in 0.3% and 3% NaCl solutions. The influence of alloy production route on microstructure has been examined by scanning electron microscopy, Auger electron spectroscopy and secondary ion mass spectrometry. An improvement in performance of powder metallurgy (PM) materials, compared with the cast alloy, was evident in solutions of low chloride concentration; less striking differences were revealed in high chloride concentration. Both powder metallurgy and cast alloys show two main types of precipitates, which were identified as Zn-Mg and Zr-Sc base intermetallic phases. The microstructure of the PM alloys is refined compared with the cast material, which assists understanding of the corrosion performance. The corrosion process commences with dissolution of the Zn-Mg base phases, with the relatively coarse phases present in the cast alloy showing ready development of corrosion

20

Corrosion of two kinds of cast steels containing chromium in hot concentrated alkaline  

Directory of Open Access Journals (Sweden)

Full Text Available A typical hot concentrated alkaline corrosion environment exists in alumina metallurgical industry, so that steel materials with outstanding alkaline corrosion resistance are strongly demanded for its processing equipment. In this paper, the corrosion resistance of two kinds of martensitic cast steels containing chromium in static 303g/L NaOH alkaline solution at 85? was studied through polarization and potential-time curves, corrosion weight loss and corrosion morphology analysis. Experimental results showed that protection effect by passive film of cast steel containing Cr was temporary. The low carbon steel without Cr content also exhibited chemical passivity in the same solution. The corrosion mode of the tested Cr-containing cast steel was composed of active dissolving corrosion and caustic embrittlement cracking. Dissolving corrosion was the primary mechanism for the induced weight loss, while severe caustic embrittlement cracking was secondary. With the increase of chromium content in the cast steel, the tendency of the caustic embrittlement cracking decreased, while the active dissolving corrosion increased.

LI Wei

2007-02-01

 
 
 
 
21

Corrosion properties and corrosion evolution of as-cast AZ91 alloy with rare earth yttrium  

International Nuclear Information System (INIS)

Highlights: ? Minor addition of Y will increase the corrosion resistance of AZ91 alloy, and 0.3 wt.% Y is the optimum addition. ? A film composed of Mg(OH)2, MgCO3, Al(OH)3 and Al2O3 is formed on the surface of AZ91 alloy with rare earth Y free. ? The film of AZ91 alloy with 0.3 wt.% Y is mainly composed of Mg(OH)2 and MgCO3 without any Al(OH)3 and Al2O3. ? The relative quantity of MgCO3 in the surface film of AZ91 + 0.3 wt.% Y is bigger than that of AZ91 alloy with Y free. ? Y2O3 phase is found in the surface film of alloy III, which benefits to stabilize the surface film. -- Abstract: The corrosion resistance property and the corrosion evolution of as-cast AZ91 alloy with rare earth Y addition are investigated by using immersion tests, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). The results show that the proper amount of Y in the alloys can improve the corrosion resistance of AZ91 alloys effectively. With the increment of Y, the corrosion rate of the modified AZ91 alloys by Y addition was markedly less than that of AZ91 alloy. The corrosion rate of AZ91 alloy with 0.3 wt.% Y was the slightest, but further addition of Y content over 0.3 wt.% make the corrosion heavier. The XPS analysis suggests that the compound film of AZ91 alloy with 0.3 wt.% Y is mainly composed of Mg(OH)2 and MgCO3 without any Al(OH)3 and Al2O3, in addition, Y2O3 phase is found in the compound film of AZ91 alloy with 0.3 wt.% Y, which benefits to stabilize the surface film.

22

Corrosion Behavior of the As-cast and Heat-treated ZA27 Alloy  

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Corrosion behaviour of the as-cast and heat-treated ZA27 alloy was examined. The alloy was prepared by conventional melting and casting route and then thermally processed by applying T4 heat treatment regime (solutionizing at 370 °C for 3 hours followed by water quenching and natural aging). Corrosion rate of the as-cast and heat-treated ZA27 alloy was determined in 3.5 wt. % NaCl solution through immersion test using both weight loss method and polarization resistance measurements. It was s...

Bobic, B.; Mitrovic, S.; Babic, M.; Vencl, A.; Bobic, I.

2011-01-01

23

Influence of the casting processing route on the corrosion behavior of dental alloys.  

Science.gov (United States)

Casting in the presence of oxygen may result in an improvement of the corrosion performance of most alloys. However, the effect of corrosion on the casting without oxygen for dental materials remains unknown. The aim of this study was to investigate the influence of the casting technique and atmosphere (argon or oxygen) on the corrosion behavior response of six different dental casting alloys. The corrosion behavior was evaluated by electrochemical measurements performed in artificial saliva for the different alloys cast in two different conditions: arc melting in argon and oxygen-gas flame centrifugal casting. A slight decrease in open-circuit potential for most alloys was observed during immersion, meaning that the corrosion tendency of the materials increases due to the contact with the solution. Exceptions were the Co-based alloys prepared by plasma, and the Co-Cr-Mo and Ni-Cr-4Ti alloys processed by oxidized flame, in which an increase in potential was observed. The amount of metallic ions released into the artificial saliva solution during immersion was similar for all specimens. Considering the pitting potential, a parameter of high importance when considering the fluctuating conditions of the oral environment, Co-based alloys show the best performance in comparison with the Ni-based alloys, independent of the processing route. PMID:25491859

Galo, Rodrigo; Rocha, Luis Augusto; Faria, Adriana Claudia; Silveira, Renata Rodrigues; Ribeiro, Ricardo Faria; de Mattos, Maria da Gloria Chiarello

2014-12-01

24

Influence of the cooling rate on the corrosion resistance of duplex cast steel  

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Full Text Available The results of the influence of the cooling rate of the casting made of the acid-resistant ferritic - austenitic cast steel on the microstructure and corrosion resistance are presented in the paper. Samples cut out from the walls of the casting being cooled at the cooling rate of 3,2 - 0,5 ºC/s were used in the study. Different cooling rates create favorable conditions for the segregation processes lowering properties of castings. It was found, that differences in the polarization curves occur only in the more aggressive corrosive environment. The reason of such behaviour of cast steel is the segregation of elements dissolved in austenite and the difference in the volume fraction of ferrite and austenite in the walls of the different thickness.

B. Kalandyk

2013-01-01

25

Influence of the cooling rate on the corrosion resistance of duplex cast steel  

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The results of the influence of the cooling rate of the casting made of the acid-resistant ferritic - austenitic cast steel on the microstructure and corrosion resistance are presented in the paper. Samples cut out from the walls of the casting being cooled at the cooling rate of 3,2 - 0,5 ºC/s were used in the study. Different cooling rates create favorable conditions for the segregation processes lowering properties of castings. It was found, that differences in the polarization curves occ...

Kalandyk, B.; Starowicz, M.; Kawalec, M.; Zapa?a, R.

2013-01-01

26

The anaerobic corrosion of carbon steel and cast iron in artificial groundwaters  

International Nuclear Information System (INIS)

In Sweden, high level radioactive waste will be disposed of in a canister with a copper outer and a cast iron or carbon steel inner. If the iron insert comes into contact with anoxic geological water, anaerobic corrosion leading to the generation of hydrogen will occur. This paper presents a study of the anaerobic corrosion of carbon steel and cast iron in artificial Swedish granitic groundwaters. Electrochemical methods and gas collection techniques were used to assess the mechanisms and rates of corrosion and the associated hydrogen gas production over a range of conditions. The corrosion rate is high initially but is anodically limited by the slow formation of a duplex magnetite film. The effects of key environmental parameters such as temperature and ionic strength on the anaerobic corrosion rate are discussed

27

On Corrosion of Ferrous Metals in Typical Indian Soils Part I : Cast Iron  

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Full Text Available Corrodibility of cast iron in ten typical Indian soils, employing Schwerdtfeger's soil corrosion cell procedure and the physico-chemical properties of the soils responsible for their corrosivity have been determined. The results have been statistically analysed, interpreted and correlated with various factors. Corrosion of cast iron in non acidic soils (p/supH4-10 proceeds through electro-chemical mechanism. Usually the rate of corrosion is maximum at the beginning and with development of the film of corrosion products, the rate gradually decrease with time until it becomes more or less constant, 'Even' general corrosion is observed on most of the cases. The maximum penetration is directly proportional corrodibility. The corrosivity of soils in situ is directly poroportional to the moisture equivalent or, in turn, to the clay content. The corrosivity of soils increases with the concentration at soluble electrolytes. Ferric oxide present in a laterite soil functions as a cathodic depolariser and hence increases its corrosivity. In an acidic soil, the corrosion mainly proceeds through the mechanism of direct chemical reaction.

Brajendra Nath Tripathi

2014-05-01

28

Corrosion resistance of various bio-films deposited on austenitic cast steel casted by lost-wax process and in gypsum mould  

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This work is the next of a series concerning the improvement of austenitic cast steel utility predicted for use in implantology for complicated long term implants casted by lost-wax process and in gypsum mould. Austenitic cast steel possess chemical composition of AISI 316L medical steel used for implants. In further part of present work investigated cast steel indicated as AISI 316L medical steel. Below a results of electrochemical corrosion resistance of carbon layer and bi-layer of carbon/...

Gawron?ski, J.

2010-01-01

29

Corrosion Behavior of the As-cast and Heat-treated ZA27 Alloy  

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Full Text Available Corrosion behaviour of the as-cast and heat-treated ZA27 alloy was examined. The alloy was prepared by conventional melting and casting route and then thermally processed by applying T4 heat treatment regime (solutionizing at 370 °C for 3 hours followed by water quenching and natural aging. Corrosion rate of the as-cast and heat-treated ZA27 alloy was determined in 3.5 wt. % NaCl solution through immersion test using both weight loss method and polarization resistance measurements. It was shown that applied thermal treatment resulted in increased ductility of the heat-treated alloy and had a small beneficial effect on the corrosion resistance of ZA27 alloy.

B. Bobic

2011-06-01

30

An Electrochemical Evaluation on the Corrosion of Weld Zone in Cold Arc Welding of the Cast Iron  

International Nuclear Information System (INIS)

Cold arc welding of cast iron has been widely used with repair welding of metal structures. However its welding is often resulted in the galvanic corrosion between weld metal zone and heat affected zone(HAZ) due to increasing of hardness. In this study, corrosion properties such as hardness, corrosion potential, surface microstructures, and variation of corrosion current density of welding zone with parameters of used electrodes for cast iron welding were investigated with an electrochemical evaluation. Hardness of HAZ showed the highest value compared to other welding zone regardless of kinds of used electrodes for cast iron welding. And its corrosion potential was also shifted to more negative direction than other welding zone. In addition, corrosion current density of WM in polarization cures was qualitatively smaller than that of HAZ. Therefore galvanic corrosion may be apparently observed at HAZ. However galvanic corrosion may be somewhat controlled by using an optimum welding electrode

31

Corrosion behavior of nodular cast iron casks for low and intermediate level wastes  

International Nuclear Information System (INIS)

In applying new conditioning methods dehydrated wastes (e.g. concentrates, ion exchange resins) from operation of nuclear power plants and wastes from decommissioning (e.g., highly-activated core components) are conditioned using high integrity nodular cast iron casks without further solidification. Therefore more stringent requirements have to be made for the packaging material. The objective of the investigations was to evaluate the corrosion resistance of the cask material. For this purpose chemical corrosion tests were made applying corrosion media actually considered or postulated in accident scenarios during interim storage or after disposal in the abandoned iron ore mine Konrad or in a salt formation. The conclusion from the corrosion experiments, which have been performed up to now for the basic packaging material, indicates that nodular cast iron casks with wall thicknesses about 200 mm seem to ensure good protection for wastes especially from nuclear power plants with relatively short-lived radionuclides

32

Mechanical properties and corrosion behaviour of 18Cr-11Ni-2,5Mo cast steel  

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Full Text Available The study discusses the effect of variable carbon concentration (0,02; 0,07 and 0,14% on the mechanical properties and corrosion resistance in 3,0% NaCl solution of 18Cr-11Ni-2,5Mo austenitic cast steel. It has been proved that at the concentration of 0,07%C, products made of the examined cast steel reveal on their surface some symptoms of local corrosion. Carbon concentration raised to 0,14%C results in advanced intercrystalline corrosion and the onset of local corrosion. Carbon concentration increased from 0,02 to 0,14% also results in the tensile strength UTS raised from 487MPa to 579MPa (a nearly 20% increase with elongation El reduced from 55,3% to 49,6%, and reduction of area RA from 69,3% to 53,4%.

M. Starowicz

2009-10-01

33

A cast 7050 friction stir weld with scandium: microstructure, corrosion and environmental assisted cracking  

International Nuclear Information System (INIS)

Microstructure, corrosion and environmental cracking behavior of friction stir welded cast aluminum 7050 ingots alloyed with scandium additions was investigated. An over-aged (T7451) and a homogenization (24 h/475 deg. C) temper were applied to the as-cast plates before friction stir welding, while a post-weld heat treatment was applied to all welds to verify the changes in the corrosion behavior. It was found that the as-cast and heat treated friction stir weld samples exhibited a fully recrystallized equiaxed grain microstructure. The scandium did not significantly dissolve in any of the phases present and remained homogeneously distributed within the matrix. The as-cast friction stir weld microstructure exhibited apart from the nugget region coarse grain boundary phases, wide precipitate-free zones and coarse intragranular precipitates. The post-weld heat treatment (1 h/480 deg. C-1 h/100 deg. C boiling water and quench) increased the tensile strength of the as-cast weld, but decreased the strength of the heat treated welds. The heat treatment of the as-cast samples to an overaging (T7451) and homogenization (24 h/475 deg. C) temper increased the general corrosion susceptibility of the friction stir welds

34

Calculated phase diagrams and the corrosion of die-cast Mg-Al alloys  

International Nuclear Information System (INIS)

The corrosion of commercial die-cast Mg-Al alloys was elucidated by a study, of the corrosion in 3% NaCl, of (i) high-pressure die-cast (HPDC) model Mg-Al alloys, (ii) low-purity Mg, (iii) high-purity (HP) Mg and (iv) HP Mg heat treated at 550 deg. C. HPDC is the most important route for the production of Mg components. The corrosion of the model alloys was dominated by the Fe impurity element. The present research identified the appearance of the Fe-rich particles in the microstructure. In high magnification (?1000x to 5000x) secondary electron images, they appear as small white features, typically less than 1 ?m in diameter. In order to understand the impurity tolerance limits, (i) the appropriate corrosion literature was summarised and reviewed and (ii) Mg phase diagrams were calculated using the Pandat software package. Calculated phase diagrams can explain (i) the tolerance levels for Fe and Cu and (ii) the production of high-purity castings by means of control of melt conditions; this has high significance for the production of quality castings from recycled Mg. A full analysis requires that the Mg database be extended to include Ni, Co and some RE. The Fe tolerance limit is ?5-10 ppm for cast HP Mg heat treated at 550 deg. C. Analysis of the Mg corrosion literature indicates that several studies have been dominated by the Fe impurity content and have not dealt with the stated aims; it means that the full chemical composition should be reported in all studiition should be reported in all studies of the corrosion of Mg alloys

35

Calculated phase diagrams and the corrosion of die-cast Mg-Al alloys  

Energy Technology Data Exchange (ETDEWEB)

The corrosion of commercial die-cast Mg-Al alloys was elucidated by a study, of the corrosion in 3% NaCl, of (i) high-pressure die-cast (HPDC) model Mg-Al alloys, (ii) low-purity Mg, (iii) high-purity (HP) Mg and (iv) HP Mg heat treated at 550 deg. C. HPDC is the most important route for the production of Mg components. The corrosion of the model alloys was dominated by the Fe impurity element. The present research identified the appearance of the Fe-rich particles in the microstructure. In high magnification ({approx}1000x to 5000x) secondary electron images, they appear as small white features, typically less than 1 {mu}m in diameter. In order to understand the impurity tolerance limits, (i) the appropriate corrosion literature was summarised and reviewed and (ii) Mg phase diagrams were calculated using the Pandat software package. Calculated phase diagrams can explain (i) the tolerance levels for Fe and Cu and (ii) the production of high-purity castings by means of control of melt conditions; this has high significance for the production of quality castings from recycled Mg. A full analysis requires that the Mg database be extended to include Ni, Co and some RE. The Fe tolerance limit is {approx}5-10 ppm for cast HP Mg heat treated at 550 deg. C. Analysis of the Mg corrosion literature indicates that several studies have been dominated by the Fe impurity content and have not dealt with the stated aims; it means that the full chemical composition should be reported in all studies of the corrosion of Mg alloys.

Liu Ming [University of Queensland, Division of Materials, ARC CoE for Design in Light Metals, St. Lucia, Brisbane, Qld 4072 (Australia); Swiss Federal Laboratories for Materials Science and Technology, Uberlandstrasse 129, CH-8600 Dubendorf (Switzerland); Uggowitzer, Peter J. [ETH Zuerich, Department of Materials, CH-8093 Zurich (Switzerland); Nagasekhar, A.V. [University of Queensland, Division of Materials, ARC CoE for Design in Light Metals, St. Lucia, Brisbane, Qld 4072 (Australia); Schmutz, Patrik [Swiss Federal Laboratories for Materials Science and Technology, Uberlandstrasse 129, CH-8600 Dubendorf (Switzerland); Easton, Mark [Monash University, Department of Materials Engineering, CAST Co-operative Research Centre, Melbourne, Vic. 3800 (Australia); Song Guangling [University of Queensland, Division of Materials, ARC CoE for Design in Light Metals, St. Lucia, Brisbane, Qld 4072 (Australia); Atrens, Andrej [University of Queensland, Division of Materials, ARC CoE for Design in Light Metals, St. Lucia, Brisbane, Qld 4072 (Australia); Swiss Federal Laboratories for Materials Science and Technology, Uberlandstrasse 129, CH-8600 Dubendorf (Switzerland)], E-mail: andrejs.atrens@uq.edu.au

2009-03-15

36

Improvements in continuous casting of corrosion resistant steel  

International Nuclear Information System (INIS)

The results of studies on improvements in continuous casting of 12Kh18N10T steel with argon protection are presented. The effect of the method of metal supply to the crystallizer on the ingots quality is considered. The conclusion is drawn on the necessity of continuous steel casting with maximum possible- and constant rate. The economic effect as a result of the above improvements constitutes 37 rbes/t

37

Effect of tempering on corrosion resistance of cast aluminium bronzes  

International Nuclear Information System (INIS)

The subject of this study is corrosion resistance of aluminium bronzes, which are copper base alloys containing aluminium up to 12% with additions of nickel, iron and manganese. The main conclutions that can be drawn are: (1) The dealloying corrosion resistance of nickel-aluminium bronze is much better than that of aluminium bronze with iron and manganese additions, but it is not immune; (2) The dealloying corrosion resistance of aluminium bronzes can be improved by appropiate heat treatments. The best properties were obtained by temperering between 600 and 800 deg C, depending on the initial microstructure; (3) In crevice conditions, where local acidification can occur, dealloying of aluminium bronzes is a consequence of the preferential attack of aluminium-rich phases. By appropriate tempering, a uniform distribution of aluminium-rich phases is obtained and the continous path for selective corrosion is not formed

38

Improvement in corrosion resistance of a nodular cast iron surface modified by plasma beam treatment  

International Nuclear Information System (INIS)

Nodular cast iron (NCI) specimens with corrosion-resistant surfaces were fabricated by plasma beam treatment and tempering (400 °C, 1 h), which consisted of plasma surface melting, plasma surface melting + tempering, plasma surface alloying and plasma surface alloying + tempering. In this manner, near-surface graphite nodules were eliminated, and inter-dendrites and eutectics with a hyper-eutectic structure appeared on the modified surfaces, as indicated by SEM. The corrosion behaviour of treated specimens in 3.5 wt% NaCl was characterised by electrochemical methods and compared with that of an untreated NCI specimen at 25 °C. The corrosion resistance ranked as follows: surface-alloyed and tempered specimen > surface-alloyed specimen ? surface-melted and tempered specimen > surface-melted specimen > the untreated NCI specimen. Metallographic as well as electrochemical corrosion studies illustrate the beneficial effects of surface modification in refining the microstructure and in enhancing the corrosion resistance of NCI.

39

A new corrosion protection coating system for pressure-cast aluminium automotive parts  

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A simple to employ corrosion protecting coating based on sol-gel derived new nanocomposites for Al alloys has been developed. This composite coating reacts to the Al surface by formation of a thermodynamically stabilized interface. Moreover, for pressure cast Al, the coating process can be used for sealing the pores at the same time.

Schmidt, Helmut K.; Langenfeld, Stefan; Nass, Ru?diger

1997-01-01

40

The vasculature of the periodontal ligament: a scanning electron microscopic study using corrosion casts in the rat.  

Science.gov (United States)

The purpose of this study was to examine the 3-dimensional architecture of the microvascular system of the rat periodontal ligament (PDL). Vascular corrosion casts were prepared and examined by scanning electron microscopy. Cervically, arterioles and venules communicated with the profuse capillary network of the gingiva. The mid-root segment of the PDL contained arterioles and venules that mainly coursed occluso-apically near the alveolar wall, as well as capillary loops located closer to the root surface. Arterioles entered the PDL through vascular canals from the bone marrow, then coursed coronally and branched into an interconnected network of capillaries. The capillaries formed hairpin loops pointing coronally. At the tip, the capillary loops were enlarged in diameter and had an irregular luminar surface. The capillaries then coursed apically, anastomosing freely, until entering a venule. Large venules mainly followed a coronal-apical path, giving the PDL vasculature a palisade-like appearance. These vessels either left the PDL through vascular canals in the alveolar wall or connected in an apical, venous cap with venules exiting through the apical foramen. The results show that the microvasculature forms a highly organized system presumably related to the specialized functions of the periodontium. Cervically, a dense capillary system may be required for antimicrobial defense and rapid tissue turnover. The vasculature in the middle segment supports the suspensory structures, while the venous cap in the apical region may be designed to cushion masticatory forces.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7853133

Selliseth, N J; Selvig, K A

1994-11-01

 
 
 
 
41

Characteristics of low nickel ferritic-austenitic corrosion resistant cast steel  

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Full Text Available The article presents the results of microscopic examinations of corrosion resistant cast steel with reduced nickel content obtained in a test casting with varying wall thickness. Investigations were carried out in as-cast condition and after heat treatment. Regardless of the casting wall thickness, increasing the manganese and nitrogen content to about 5 % and 2 500 ppm, respectively, yields the material with a two-phase microstructure containing ferrite in an amount of 55,6 ÷ 57,2 % (magnetic method and 52,3 ÷ 55,2 % (analytical method. Based on the results of metallographic examinations, total elimination of the secondary austenite from the microstructure was observed. Microhardness measurements showed average values of 352,3 ?HV20 and 267 ?HV20 for the chromium ferrite and austenite, respectively.

B. Kalandyk

2014-10-01

42

Evaluation of corrosion resistance of casting magnesium alloy AZ31 in NaCl solutions  

International Nuclear Information System (INIS)

The results of tests of corrosion resistance of casting magnesium alloy AZ31 in NaCl solutions of 0,01 to 2 M concentration have been presented. Electrochemical measurements were carried out with application of VoltaLab (registered) PGP201 system by Radiometer. On the ground of registered polarisation curves, typical features characterising alloy resistance to electrochemical corrosion, i.e. corrosion potential, polarisation resistance, corrosion current density and corrosion rate, were determined. Electrochemical impedance spectroscopy was applied for evaluation of phenomena that occurred on the surface of the tested alloy. Resistance to corrosion was tested by means of immersion method for 1 to 5 days. By means of scanning electron microscope with field emission FE SEM S-4200 Hitachi in cooperation with spectrometer EDS Voyager 3500 Noran Instruments, quantitative and qualitative analysis of chemical composition in micro-zones was made. The study also presents the results of measurements of geometrical features of AZ31 alloy surface after corrosion tests. The results of the tests show undoubtedly deterioration of corrosion properties of magnesium alloy AZ31 together with the increase in molar concentration of NaCl solution.

43

Evaluation of corrosion resistance of casting magnesium alloy AZ31 in NaCl solutions  

Energy Technology Data Exchange (ETDEWEB)

The results of tests of corrosion resistance of casting magnesium alloy AZ31 in NaCl solutions of 0,01 to 2 M concentration have been presented. Electrochemical measurements were carried out with application of VoltaLab (registered) PGP201 system by Radiometer. On the ground of registered polarisation curves, typical features characterising alloy resistance to electrochemical corrosion, i.e. corrosion potential, polarisation resistance, corrosion current density and corrosion rate, were determined. Electrochemical impedance spectroscopy was applied for evaluation of phenomena that occurred on the surface of the tested alloy. Resistance to corrosion was tested by means of immersion method for 1 to 5 days. By means of scanning electron microscope with field emission FE SEM S-4200 Hitachi in cooperation with spectrometer EDS Voyager 3500 Noran Instruments, quantitative and qualitative analysis of chemical composition in micro-zones was made. The study also presents the results of measurements of geometrical features of AZ31 alloy surface after corrosion tests. The results of the tests show undoubtedly deterioration of corrosion properties of magnesium alloy AZ31 together with the increase in molar concentration of NaCl solution.

Przondziono, J; Hadasik, E; Wieczorek, J [Department of Materials Technology, Silesian University of Technology, Krasihskiego 8, 40-019 Katowice (Poland); Walke, W [Institute of Engineering Materials and Biomaterials, Silesian University of Technology, Konarskiego 18a, 44-100 Gliwice (Poland); Szala, J, E-mail: joanna.przondziono@polsl.pl [Department of Materials Science, Silesian University of Technology, Krasihskiego 8, 40-019 Katowice (Poland)

2011-05-15

44

Corrosion resistance of various bio-films deposited on austenitic cast steel casted by lost-wax process and in gypsum mould  

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Full Text Available This work is the next of a series concerning the improvement of austenitic cast steel utility predicted for use in implantology for complicated long term implants casted by lost-wax process and in gypsum mould. Austenitic cast steel possess chemical composition of AISI 316L medical steel used for implants. In further part of present work investigated cast steel indicated as AISI 316L medical steel. Below a results of electrochemical corrosion resistance of carbon layer and bi-layer of carbon/HAp deposited on AISI 316L researches are presented. Coatings were manufactured by RF PACVD and PLD methods respectively. Obtained results, unequivocally indicates on the improvement of this type of corrosion resistance by substrate material with as deposited carbon layer. While bi-layer of carbon/HAp are characterized by very low corrosion resistance.

J. Gawro?ski

2010-01-01

45

Influence of cerium additions on the corrosion behaviour of high pressure die cast AM50 alloy  

International Nuclear Information System (INIS)

Highlights: ? Ce addition modified the microstructure of AM50 magnesium alloy. ? Ce addition reduces grain size of AM50 magnesium alloy. ? Ce addition causes the formation of a new phase called ?-Al11Ce3. ? The corrosion resistance is significantly increased by the addition of cerium to the AM50 alloy. - Abstract: The influence of Ce additions to AM50 magnesium alloy prepared by high pressure die casting on the microstructure and corrosion behaviour has been investigated. The corrosion behaviour was evaluated by hydrogen evolution, salt spray, potentiodynamic polarization and electrochemical impedance experiments. The results show that Ce addition promotes the formation of Al11Ce3 phase and reduces the amount of ?-phase (Mg17Al12). The corrosion resistance is improved with increasing Ce content which can be attributed to the formation of Al11Ce3 phase, reduction of ?-phase (reduced galvanic effects) and higher purity of AME50X alloys (melt cleaning effects).

46

Microstructure Aspects of a Newly Developed, Low Cost, Corrosion-Resistant White Cast Iron  

Science.gov (United States)

The purpose of this work is to study the influence of heat treatment on the corrosion resistance of a newly developed white cast iron, basically suitable for corrosion- and wear-resistant applications, and to attain a microstructure that is most suitable from the corrosion resistance point of view. The composition was selected with an aim to have austenitic matrix both in as-cast and heat-treated conditions. The difference in electrochemical potential between austenite and carbide is less in comparison to that between austenite and graphite. Additionally, graphitic corrosion which is frequently encountered in gray cast irons is absent in white cast irons. These basic facts encouraged us to undertake this work. Optical metallography, hardness testing, X-ray diffractometry, and SEM-EDX techniques were employed to identify the phases present in the as-cast and heat-treated specimens of the investigated alloy and to correlate microstructure with corrosion resistance and hardness. Corrosion testing was carried out in 5 pct NaCl solution (approximate chloride content of sea water) using the weight loss method. In the investigated alloy, austenite was retained the in as-cast and heat-treated conditions. The same was confirmed by X-ray and EDX analysis. The stability and volume fraction of austenite increased with an increase of heat-treated temperature/time with a simultaneous decrease in the volume fraction of massive carbides. The decrease in volume fraction of massive carbides resulted in the availability of alloying elements. These alloying elements, on increasing the heat treatment temperature or increasing the soaking period at certain temperatures, get dissolved in austenite. As a consequence, austenite gets enriched as well as becomes more stable. On cooling from lower soaking period/temperature, enriched austenite decomposes to lesser enriched austenite and to a dispersed phase due to decreasing solid solubility of alloying elements with decreasing temperature. The dispersed second phase precipitated from the austenite adversely influenced corrosion resistance due to unfavorable morphology and enhanced galvanic action. Corrosion rate and hardness were found to decrease with an increase in heat treatment temperatures/soaking periods. It was essentially due to the increase in the volume fraction and stability of the austenitic matrix and favorable morphology of the second phase (carbides). The corrosion resistance of the investigated alloy, heat treated at 1223 K (950 °C) for 8 hours, was comparable to that of Ni-Resist iron. Thus, a microstructure comprising austenite and nearly spherical and finer carbides is the most appropriate from a corrosion point of view. Fortunately, the literature reveals that the same microstructure is also well suited from a wear point of view. It confirms that this investigated alloy will be suitable for corrosive-wear applications.

Sain, P. K.; Sharma, C. P.; Bhargava, A. K.

2013-04-01

47

Rapid casting of patterned vascular networks for perfusable engineered three-dimensional tissues  

Science.gov (United States)

In the absence of perfusable vascular networks, three-dimensional (3D) engineered tissues densely populated with cells quickly develop a necrotic core. Yet the lack of a general approach to rapidly construct such networks remains a major challenge for 3D tissue culture. Here, we printed rigid 3D filament networks of carbohydrate glass, and used them as a cytocompatible sacrificial template in engineered tissues containing living cells to generate cylindrical networks that could be lined with endothelial cells and perfused with blood under high-pressure pulsatile flow. Because this simple vascular casting approach allows independent control of network geometry, endothelialization and extravascular tissue, it is compatible with a wide variety of cell types, synthetic and natural extracellular matrices, and crosslinking strategies. We also demonstrated that the perfused vascular channels sustained the metabolic function of primary rat hepatocytes in engineered tissue constructs that otherwise exhibited suppressed function in their core.

Miller, Jordan S.; Stevens, Kelly R.; Yang, Michael T.; Baker, Brendon M.; Nguyen, Duc-Huy T.; Cohen, Daniel M.; Toro, Esteban; Chen, Alice A.; Galie, Peter A.; Yu, Xiang; Chaturvedi, Ritika; Bhatia, Sangeeta N.; Chen, Christopher S.

2012-09-01

48

Physicochemical studies of glucose, gellan gum, and hydroxypropyl cellulose--inhibition of cast iron corrosion.  

Science.gov (United States)

Glucose, gellan gum, and hydroxypropyl cellulose were studied against the acid corrosion of cast iron by means of weight loss, potentiodynamic polarization, and AC impedance spectroscopy techniques. The inhibition efficiency was found to increase with increasing concentration of the inhibitors. The effect of immersion time and temperature were also studied. The addition of potassium iodide to the corrosion-inhibition system showed both antagonism and synergism toward inhibition efficiency. Polarization studies revealed the mixed-type inhibiting nature of the carbohydrates. The adsorption of inhibitors on the cast iron surface obeys Langmuir adsorption isotherm model, both in presence and absence of KI. Physical interaction between the inhibitor molecules and the iron surface was suggested by the thermochemical parameters, rather than chemical interaction. PMID:23618271

Rajeswari, Velayutham; Kesavan, Devarayan; Gopiraman, Mayakrishnan; Viswanathamurthi, Periasamy

2013-06-01

49

Effect of extracellular polymeric substances on corrosion of cast iron in the reclaimed wastewater.  

Science.gov (United States)

Microorganisms were cultured in the R2A medium with inoculum from biofilm in a reclaimed wastewater distribution system and then extracellular polymeric substances (EPS) were extracted from the culture. Characterization of EPS and their effects on the corrosion of cast iron were examined. EPS extracted from different culturing stages contained different proportions of protein and polysaccharide but with similar functional groups. All types of EPS could inhibit cast iron corrosion and the EPS from the stationary stage had the highest inhibition efficiency. The inhibition efficiency was increased with addition of a small amount of EPS while decreased with excessive amount of EPS. EPS formed a protective film on the metal surface, which retarded the cathodic reduction of oxygen. Excessive amount of EPS promoted anodic dissolution through EPS-Fe binding. The CO and C(O, N) in EPS could be the anodic electrochemical sites with possible products of C(C, H). PMID:24618284

Jin, Juntao; Wu, Guangxue; Zhang, Zhenhua; Guan, Yuntao

2014-08-01

50

Corrosion behaviour of ductile cast irons partially modified with silicon in 0.03 M NaCl  

International Nuclear Information System (INIS)

NaCl. The increasing demand of ductile cast irons with extensive technological applications leads to enlarge the corrosion resistance of this group of metallic materials. In this sense, the use of different chemical compositions on such cast irons becomes one of the most interesting aspects among the different ways to improve their behaviour against corrosion due to the extra opportunity for increasing the mechanical properties. Additionally such improvements have to be made without any increase of processing costs to keep the interesting competitiveness of developed cast irons. In the present work the preliminary results obtained from corrosion tests made on a group of cast irons with different chemical compositions are presented. Among ductile cast irons, silicon content has been varied in order to investigate the effect of this element on corrosion resistance of the alloys. The obtained results show a slight improvement of this property for the alloys with high silicon content with respect to the conventional ones though such effect was found in the first time period of the corrosion tests. Interestingly this improvement was found for alloys that exhibit better tensile properties than the conventional ductile irons. Thus an important way for developing new ductile cast irons with improved corrosion properties by alloying has been opened. (Author)

51

Corrosion Behaviour of Al (6063 Alloy (As-Cast and Age Hardened in H2SO4 Solution  

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Full Text Available The heat treatment and corrosion of aluminum 6063 alloy was investigated. The aim of this work was to determine the effect of heat treatment on the microstructure and the corrosion of aluminum 6063 alloy using weight loss method. The samples conditions were; as-cast, solution treated, supersaturated and age hardened condition. They were soaked in a 10 molar solution of sulphuric acid and monitored with time. The corrosion rate was calculated for various immersion periods. The result shows that the corrosion rate of the alloy was due to the nature of heat treatment given to the samples. Similarly, it was also found that the corrosion rate of the Al(6063 alloy was higher in the as-cast sample compared to the heat treated alloy. The passivation on the heat treated Al(6063 alloy was a little more stable therefore reducing the corrosion rate after 35 days of immersion for the aged hardened samples.

F. A. Ovat

2012-08-01

52

General corrosion and galvanic corrosion properties of differently PVD treated magnesium die cast alloy AZ91  

Energy Technology Data Exchange (ETDEWEB)

Developing PVD coating systems with better corrosion resistance leads to a duplex process, consisting of a plasma anodisation and an Al{sub 2}O{sub 3} top coating which can both be performed in a modified commercial PVD unit. The tested specimens were investigated by means of optical microscopy, SEM and EDX. Furthermore a novel immersion technique to determine the time dependent corrosion behavior of coated magnesium alloys is introduced. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Hoche, H.; Broszeit, E.; Berger, C. [Staatliche Materialpruefungsanstalt und Fachgebiet und Institut fuer Werkstoffkunde, Technischen Universitaet Darmstadt, D-64283 Darmstadt (Germany); Blawert, C. [GKSS Forschungszentrum Geesthacht GmbH, D-21502 Geesthacht (Germany)

2003-12-01

53

Electrochemical impedance spectroscopy evaluation of the corrosion behavior of die cast and thixocast AXJ530 magnesium alloy in chloride solution  

Energy Technology Data Exchange (ETDEWEB)

The most used commercial magnesium alloy is AZ91D, but its creep resistance is low. A new Mg-Al-Ca-Sr alloy (AXJ530) has better creep resistance than AZ91. However, the corrosion resistance of die cast AXJ530 is much lower than AZ91. To improve its corrosion performance, the alloy is thixocast from billets previously cast with electromagnetic stirring. This thixocast AXJ530 has comparable corrosion property to AZ91 in 0.05 M NaCl solution. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

Jin, S.; Amira, S.; Ghali, E. [Department of Mining, Metallurgical and Materials Engineering, Laval University, Quebec, QC (Canada)

2007-01-15

54

Blood vessel remodeling in pig ovarian follicles during the periovulatory period: an immunohistochemistry and SEM-corrosion casting study  

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Full Text Available Abstract Background The present research aims to describe the process of vascular readjustment occurring in pig ovary during the periovulatory phase (from LH surge to ovulation that drives the transformation of the follicle, a limited blood supplied structure, into the corpus luteum, a highly vascularised endocrine gland required to maintain high levels of progesterone in pregnancy. The swine model was chosen because it is characterized by a long periovulatory window (about 40–44 hrs-similar to human that permits to recover follicles at a precise endocrinological timing. Methods By validated hormonal protocol (eCG+hCG, able to mimic the physiologic gonadotropin stimulation, preovulatory follicles (PreOFs, 60 h-eCG, follicles in the middle (early periovulatory follicles, EPerOFs, 18 h-hCG or late (LPerOFs, 36 h-hCG periovulatory phase were isolated from prepubertal gilts. To understand the angiogenic process, morphological/morphometrical analyses were performed by combining immunohistochemistry (IHC and SEM of vascular corrosion casts (VCC techniques. Results PreOFs showed a vascular plexus with proliferating endothelial cells (EPI. This plexus was characterized by a dense inner capillary network, with angiogenic figures, connected to the outer network by anastomotic vessels (arterioles and venules of the middle network. EPerOFs decreased their EPI, blood vessel extension in the outer network, and evidenced a reduced compactness of blood vessels. In LPerOFs, a rapid neovascularization was associated to an intensive tissue remodeling: the follicle acquired an undulated aspect presenting arterioles/venules near the basal membrane, increased vascular extension by EPI, sprouting and non-sprouting angiogenesis. The analysis of vascular geometric relations and branching angles evidenced similar values at all stages. Conclusion These data allow us to hypothesize that EPerOFs are in a quiescent status. LPerOFs represent the "metamorphic" follicles that rapidly turn-on angiogenesis to sustain a successful corpus luteum formation. Particularly, it is interesting to underlie that the non-sprouting angiogenesis, typical of structures in rapid neovascularization, occurred only in the LPerOFs. Moreover, vascular geometric relations showed as blood vessel remodeling occurs with the "maximum output and the minimum energetic expense". This knowledge will allow to better understand the mechanisms regulating the reproductive success and to clarify the complex physiological angiogenic process in adult tissues.

Berardinelli Paolo

2009-07-01

55

Effects of microbial redox cycling of iron on cast iron pipe corrosion in drinking water distribution systems.  

Science.gov (United States)

Bacterial characteristics in corrosion products and their effect on the formation of dense corrosion scales on cast iron coupons were studied in drinking water, with sterile water acting as a reference. The corrosion process and corrosion scales were characterized by electrochemical and physico-chemical measurements. The results indicated that the corrosion was more rapidly inhibited and iron release was lower due to formation of more dense protective corrosion scales in drinking water than in sterile water. The microbial community and denitrifying functional genes were analyzed by pyrosequencing and quantitative polymerase chain reactions (qPCR), respectively. Principal component analysis (PCA) showed that the bacteria in corrosion products played an important role in the corrosion process in drinking water. Nitrate-reducing bacteria (NRB) Acidovorax and Hydrogenophaga enhanced iron corrosion before 6 days. After 20 days, the dominant bacteria became NRB Dechloromonas (40.08%) with the protective corrosion layer formation. The Dechloromonas exhibited the stronger corrosion inhibition by inducing the redox cycling of iron, to enhance the precipitation of iron oxides and formation of Fe3O4. Subsequently, other minor bacteria appeared in the corrosion scales, including iron-respiring bacteria and Rhizobium which captured iron by the produced siderophores, having a weaker corrosion-inhibition effect. Therefore, the microbially-driven redox cycling of iron with associated microbial capture of iron caused more compact corrosion scales formation and lower iron release. PMID:25150521

Wang, Haibo; Hu, Chun; Zhang, Lili; Li, Xiaoxiao; Zhang, Yu; Yang, Min

2014-11-15

56

The development of high strength corrosion resistant precipitation hardening cast steels  

Science.gov (United States)

Precipitation Hardened Cast Stainless Steels (PHCSS) are a corrosion resistant class of materials which derive their properties from secondary aging after a normalizing heat treatment step. While PHCSS materials are available in austenitic and semi-austenitic forms, the martensitic PHCSS are most widely used due to a combination of high strength, good toughness, and corrosion resistance. If higher strength levels can be achieved in these alloys, these materials can be used as a lower-cost alternative to titanium for high specific strength applications where corrosion resistance is a factor. Although wrought precipitation hardened materials have been in use and specified for more than half a century, the specification and use of PHCSS has only been recent. The effects of composition and processing on performance have received little attention in the cast steel literature. The work presented in these investigations is concerned with the experimental study and modeling of microstructural development in cast martensitic precipitation hardened steels at high strength levels. Particular attention is focused on improving the performance of the high strength CB7Cu alloy by control of detrimental secondary phases, notably delta ferrite and retained austenite, which is detrimental to strength, but potentially beneficial in terms of fracture and impact toughness. The relationship between age processing and mechanical properties is also investigated, and a new age hardening model based on simultaneous precipitation hardening and tempering has been modified for use with these steels. Because the CB7Cu system has limited strength even with improved processing, a higher strength prototype Fe-Ni-Cr-Mo-Ti system has been designed and adapted for use in casting. This prototype is expected to develop high strengths matching or exceed that of cast Ti-6Al-4V alloys. Traditional multicomponent constitution phase diagrams widely used for phase estimation in conventional stainless steels, give poor estimates of secondary phases in PHCSS. No measureable retained austenite was observed in any of the CB7Cu-1 steels studied, in spite of the fact that austenite is predicted by the constitution diagrams. A designed experiment using computationally derived phase equilibrium diagrams and actual experimental tests on CB7Cu of different compositions suggests that the ferrite phase is less stable than the constitution diagrams for austenitic stainless steels suggest. Delta ferrite was also more stable in slower-cooled sand cast material as compared to thin, fast-cooled investment cast material. High temperature solutionizing treatments were effective in dissolving delta ferrite at temperatures above 1900°F (˜1040°C). Delta ferrite dissolution was found to proceed at high rates during initial dissolution, and then was found to slow after 1 hour. Diffusion during the later stages is well-predicted by classical diffusion models. Repeated solution treatments were found to modestly increase both ductility and strength, likely due to subgrain refinement through austenite regrowth. Multistaged aging provided superior strength and toughness increases over similarly peak-aged and near peak-aged material aged at a single temperature. Peak-aged material fractography suggested that low energy quasi-cleavage fracture was likely due to age precipitate embrittlement along with some nucleation of MnS particulates at prior austenite grain boundaries. Yield strengths approaching 190 ksi (1310MPa) can be achieved in CB7Cu-1 if appropriate best-practices "+" processing techniques are used. This includes hot isostatic processing to reduce solidification segregation and heal microporosity, high temperature homogenization for effective age hardening and ferrite reduction, double-cycle solutionizing for structure refinement, and multistaged age strengthening for finer precipitate control. The experimental prototype 11-11PH (Fe-Ni-Cr-Ti-Mo) casting alloys was cast and was found to be delta-ferrite free in the as-cast condition. In this material, proper quench process

Abrahams, Rachel A.

57

Corrosion resistances and passivation of powder metallurgical and conventionally cast 316L and 2205 stainless steels  

International Nuclear Information System (INIS)

Highlights: ? Corrosion of powder metallurgical (P/M) and conventional steels has been compared. ? P/M 316L steel has higher pitting corrosion resistance than conventional 316L steel. ? Differences in the passivation process were found for the steels in 0.5 M HCl. ? The presence of three mixed potentials is explained using the mixed potential theory. ? XPS results show differences in the composition and thickness of the passive films. - Abstract: The corrosion resistances and passivation of austenitic 316L and duplex 2205 powder metallurgical (P/M) steels, produced by gas atomizing and hot isostatic pressing (HIP), have been compared with those of their conventional cast counterparts. P/M 316L steel is shown to have significantly higher pitting corrosion resistance than conventional 316L steel in 0.5 M HCl. This effect is ascribed to the fine grained microstructure of the P/M 316L steel yielding an improved passive layer. The latter hypothesis is supported by photoelectron spectroscopy data demonstrating differences between the thickness and composition of the passive layers for the 316L steels.

58

Risk based service life prediction of underground cast iron pipes subjected to corrosion  

International Nuclear Information System (INIS)

Aging and deterioration of underground cast iron pipes is inevitable after their long time in service, with corrosion being the most predominant mechanism for pipe failures. Although considerable research has been undertaken in the past few decades, more is on the effects of corrosion on structural capacity of pipes than that on the prediction of their service life. This paper presents a methodology to quantitatively assess the risk of pipe collapse and predict its remaining service life using a time-dependent reliability theory. The concept of stress intensity in fracture mechanics is employed to establish the failure criterion of pipe collapse. An empirical model is derived for maximum pit growth of corrosion from the available data based on mathematical regressions. An example is provided to illustrate the application of the proposed method. It is found in the paper that the risk of pipe collapse increases with an increase in the diameter of the pipe for both external and internal corrosion. It is also found that the tougher the pipe is, the smaller the risk of its collapse. The paper concludes that a time-dependent reliability method is a very useful tool to predict the risk of pipe collapse and its remaining service life. The proposed method can help the water industry develop rehabilitation or replacement strategy for existing pipe networks with a view for better management of the pipe asset

59

Corrosion behaviour of chemical conversion treatments on as-cast Mg-Al alloys: Electrochemical and non-electrochemical methods  

Energy Technology Data Exchange (ETDEWEB)

Magnesium alloys are often used in as-cast conditions. So, the aim of this work is to characterize the corrosion protection of as-cast AZ91D alloys coated with simple chemical conversion (phosphate-permanganate, and cerium-based coatings). With the two coatings, the electrochemical measurements show that the corrosion protection is due to both the inhibition of cathodic and anodic reactions, because of the presence of stable CeO{sub 2} or manganese oxides in basic pH. Nevertheless, the non-electrochemical tests of corrosion are required to bring to light the healing effect of phosphate-permanganate coating compared to Ce-coating and to describe the corrosion behaviour completely. Finally phosphoric and soda pickling associated to phosphate-permanganate conversion treatment or cerium coating are ecologically efficient alternatives to fluoride-based pickling and the chromating treatment.

Rocca, E. [Institut Jean Lamour UMR CNRS 7198, Nancy Universite - Corrosion Group, B.P. 70239, 54506 Vandoeuvre-Les-Nancy (France)], E-mail: emmanuel.rocca@lcsm.uhp-nancy.fr; Juers, C.; Steinmetz, J. [Institut Jean Lamour UMR CNRS 7198, Nancy Universite - Corrosion Group, B.P. 70239, 54506 Vandoeuvre-Les-Nancy (France)

2010-06-15

60

Effect of different Mo contents on tensile and corrosion behaviors of CD4MCU cast duplex stainless steels  

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In the present study, the effect of Mo contents on the microstructure, tensile and corrosion behaviors of as-solutionized CD4MCU cast duplex stainless steel was examined. The polarization test was conducted in 3.5% NaCl +5% H2SO4 aqueous solution for general corrosion resistance and the slow strain rate tests were also conducted in air and 3.5% NaCl+5% H2SO4 aqueous solution to study the Stress Corrosion Cracking (SCC) of the present alloy. A substantial microstructural evolution of CD4MCU cast duplex stainless steel was observed with different Mo contents, which in turn affected the tensile and corrosion behaviors significantly. The beneficial effect of Mo on improving the corrosion and the SCC resistances was largely overwhelmed by this variation of microstructural characteristics. The relationship between the microstructural evolution and the tensile and corrosion behavior of CD4MCU cast duplex stainless steels with different Mo contents was discussed based on the optical and SEM micrographic and fractographic observations

 
 
 
 
61

Laser treatment of dual matrix structured cast iron surface: Corrosion resistance of surface  

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Laser gas assisted treatment of dual matrix structured cast iron surface is carried out and the corrosion response of the surface is examined. A carbon film containing 15% SiC particles and remaining 85% carbon are formed at the workpiece surface prior to the laser treatment process. The formation of carbon film enhances the absorption of the incident laser beam and accommodates uniformly the SiC particles at the workpiece surface. Nitrogen at high pressure is used as an assisting gas during the laser treatment process. Metallurgical and morphological changes in the laser treated layer are examined using a scanning electron microscope, energy dispersive spectroscopy, and X-ray diffraction. Electrochemical tests are carried out to measure the corrosion response of the laser treated and untreated workpiece surfaces. It is found that laser treatment results in a dense layer consisting of fine grains, partially dissolved SiC, and nitrogen compounds in the treated region, which improves corrosion resistance of the laser treated workpiece surface.

Yilbas, B. S.; Toor, I.; Karatas, C.; Malik, J.; Ovali, I.

2015-01-01

62

Effects of disinfectant and biofilm on the corrosion of cast iron pipes in a reclaimed water distribution system.  

Science.gov (United States)

The effects of disinfection and biofilm on the corrosion of cast iron pipe in a model reclaimed water distribution system were studied using annular reactors (ARs). The corrosion scales formed under different conditions were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM), while the bacterial characteristics of biofilm on the surface were determined using several molecular methods. The corrosion scales from the ARs with chlorine included predominantly ?-FeOOH and Fe2O3, while CaPO3(OH)·2H2O and ?-FeOOH were the predominant phases after chloramines replaced chlorine. Studies of the consumption of chlorine and iron release indicated that the formation of dense oxide layers and biofilm inhibited iron corrosion, causing stable lower chlorine decay. It was verified that iron-oxidizing bacteria (IOB) such as Sediminibacterium sp., and iron-reducing bacteria (IRB) such as Shewanella sp., synergistically interacted with the corrosion product to prevent further corrosion. For the ARs without disinfection, ?-FeOOH was the predominant phase at the primary stage, while CaCO3 and ?-FeOOH were predominant with increasing time. The mixed corrosion-inducing bacteria, including the IRB Shewanella sp., the IOB Sediminibacterium sp., and the sulfur-oxidizing bacteria (SOB) Limnobacter thioxidans strain, promoted iron corrosion by synergistic interactions in the primary period, while anaerobic IRB became the predominant corrosion bacteria, preventing further corrosion via the formation of protective layers. PMID:22209261

Wang, Haibo; Hu, Chun; Hu, Xuexiang; Yang, Min; Qu, Jiuhui

2012-03-15

63

Moessbauer studies of the corrosion products of cast iron in aqueous ammonium nitrate solution  

International Nuclear Information System (INIS)

The corrosion products of cast iron in 45% NH4NO3 solution at different temperatures have been studied using mainly Moessbauer spectroscopy. Ferrihydrite (Fe5HO8x4H2O or 5Fe2O3x9H2O) is found along with ?-FeOOH in the initial stages of the reaction at room temperature. At a later stage, partial dissolution of ?-FeOOH takes place and magnetite is precipitated. Above 80 deg C either Fesub(3-x)Osub(4) or Fe5HO8x4H2O or ?-Fe2O3 is formed as the major product depending on the ratio of the reactants. (author)

64

Dental casting alloys behaviour during power toothbrushing with toothpastes of various abrasivities. Part II: corrosion and ion release.  

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The purpose of this study was to evaluate the long term effect of abrasivity of toothpastes normally used over the corrosion behavior and ion release of the different dental casting alloys. Three dental casting alloys (Ni-Cr, Co-Cr and commercially pure Ti) were studied. Four specimens of each material were immersed, brushed without paste or brushed with one of four toothpastes of different Relative Dentine Abrasivity (RDA 50, 52, 80, and 114). An electric toothbrush with a load of 250 g was used for 420 min. Corrosion behavior was determined by means a potenciostat with high sensitivity and the ion release determined by Inductively Coupled Plasma-Mass Spectrometry. Two-way ANOVA and non-parametric tests were used to detect significant differences. Titanium specimens exhibited the best corrosion behavior after and before the toothbrushed, being the worst of the three alloys the Cr-Ni. Titanium oxide produced spontaneously on the Ti surface is the main cause of the high corrosion resistance of the material. However, the eutectoid of the CrNi with chemical composition between different phases produces pitting on the phases boundaries with an important decrease of the corrosion resistance. Besides, the CrNi produces high values of the Ni and Cr release. Slight increment in roughness were observed after toothbrushing and depended on the material but not on the toothpaste used. The increase of the microhardness (residual stresses) provokes a decrease of the corrosion resistance and an increase of the ion release. PMID:18389346

Molina, C; Nogués, Ll; Martinez-Gomis, J; Peraire, M; Salsench, J; Sevilla, P; Gil, F J

2008-09-01

65

Influence of Thermal Aging on Primary Water Stress Corrosion Cracking of Cast Duplex Stainless Steels  

International Nuclear Information System (INIS)

In order to evaluate the SCC (stress corrosion cracking) susceptibility of cast duplex stainless steels which are used for the main coolant piping material of pressurized water reactors (PWRs), the slow strain rate test (SSRT) and the constant load test (CLT) were performed in simulated PWR primary water at 360 C. The main coolant piping materials contain ferrite phase with ranging from 8 to 23 % and its mechanical properties are affected by long time thermal aging. The 23% ferrite material was prepared for test as the maximum ferrite content of main coolant pipes in Japanese PWRs. The brittle fracture in the non-aged materials after SSRT is mainly caused by quasi-cleavage fracture in austenitic phase. On the other hand, a mixture of quasi-cleavage fracture in austenite and ferrite phases was observed on long time aged material. Also on CLT, (2 times ?y), after 3,000 hours exposure, microcracks were observed on the surface of non-aged and aged for 10,000 hours at 400 C materials. The crack initiation site of CLT is similar to that of SSRT. The SCC susceptibility of the materials increases with aging time. It is suggested that the ferrite hardening with aging affect SCC susceptibility of cast duplex stainless steels. (authors)

66

Microstructural characteristics and corrosion behavior of a super duplex stainless steel casting  

International Nuclear Information System (INIS)

The machining of super duplex stainless steel castings is usually complicated by the difficulty involved in maintaining the dimensional tolerances required for given applications. Internal stresses originating from the solidification process and from subsequent heat treatments reach levels that exceed the material's yield strength, promoting plastic strain. Stress relief heat treatments at 520 deg. C for 2 h are an interesting option to solve this problem, but because these materials present a thermodynamically metastable condition, a few precautions should be taken. The main objective of this work was to demonstrate that, after solution annealing at 1130 deg. C and water quenching, stress relief at 520 deg. C for 2 h did not alter the duplex microstructure or impair the pitting corrosion resistance of ASTM A890/A890M Grade 6A steel. This finding was confirmed by microstructural characterization techniques, including light optical and scanning electron microscopy, and X-ray diffraction. Corrosion potential measurements in synthetic sea water containing 20,000 ppm of chloride ions were also conducted at three temperatures: 5 deg. C, 25 deg. C and 60 deg. C

67

The utility of the combination of the corrosion cast method and post mortem MSCT scans.  

Science.gov (United States)

A careful post-mortem investigation is needed to determine the cause of death of patients bearing coronary stents and to describe complications of stent implantation. The main purpose of this study was to combine post mortem methods of CT angiography and corrosion cast preparation for the visualization of coronary stenoses, coronary stents, instent restenosis, and stent occlusion. Injection-corrosion method was combined with post-mortem MSCT angiography to characterize the pathomorphological changes after stent implantation in 6 male cadaver hearts. Multi-slice computed tomography was employed to visualize the coronary artery system. For image post processing, multiplanar reconstructions, maximal intensity projections and three dimensional reconstructions were used. This study was assessing the feasibility of post mortem MSCT for intracoronary stent evaluation. We described a method for characterization of the coronary side branch stenosis caused by stent implantation. Post mortem CT imaging proved to be a feasible and highly reproducible technique for the characterization of pathological changes in the coronary system. PMID:25034501

Tör?, Klára; Matlakovics, Balázs; Dudás, Ibolyka; Karlinger, Kinga; Kiss, Mátyás; Molnár, Agnes; Nemeskéri, Agnes

2014-09-01

68

Corrosion behavior of silver-palladium dental casting alloys in artificial saliva  

Science.gov (United States)

Ag-Pd dental casting alloys have been used as alternatives to high gold alloys in restorative dentistry since the 1980s. These alloys exhibited mechanical properties superior to gold alloys and excellent adherence to porcelain in porcelain fused to metal (PFM) restorations, such as dental crowns. However, later increases in the price of palladium along with concerns regarding possible allergic reactions and palladium's cytotoxicity have limited the use of these alloys. Evaluation of the biocompatibility concern requires a better understanding of the interaction of Ag-Pd alloys with the oral environment, and the cost problem would be lessened if the palladium content could be reduced without lowering the corrosion resistance. Previous studies have shown differences in the corrosion behavior between Pd-rich and Ag-rich alloys, but the mechanisms of the two behaviors are not well understood. The purpose of this study was to characterize the electrochemical behavior of binary Ag-Pd alloys under conditions simulating the exposure in the oral cavity. Electrochemical measurements, surface and solution analysis were performed with alloy composition, electrolyte composition, and exposure time as variables. Results showed the corrosion behavior for all alloys was governed by the formation of an insoluble thiocyanate salt combined with selective dissolution of Ag for the Pd-rich alloys. The tendency to form thiocyanate was found to dominate over the tendency to form chloride, the formation of which was suggested in other studies. The electrode behavior has been explained on the basis of the theory of behavior of electrodes of the second kind. The difference in behavior of Ag-rich and Pd-rich alloys has been related to the difference in the solubility of the salts and difference in bonding of thiocyanate with Pd and Ag.

Krajewski, Katherine Mary

69

Corrosion resistance of cast irons and titanium alloys as reference engineered metal barriers for use in basalt geologic storage: a literature assessment  

International Nuclear Information System (INIS)

A survey and assessment of the literature on the corrosion resistance of cast irons and low-alloy titanium are presented. Selected engineering properties of cast iron and titanium are briefly described; however, the corrosion resistance of cast iron and titanium in aqueous solutions or in soils and their use in a basalt repository are emphasized. In evaluating the potential use of cast iron and titanium as structural barrier materials for long-lived nuclear waste packages, it is assumed that titanium has the general corrosion resistance to be used in relatively thin cross sections whereas the cost and availability of cast iron allows its use even in very thick cross sections. Based on this assumption, the survey showed that: The uniform corrosion of low-alloy titanium in a basalt environment is expected to be extremely low. A linear extrapolation of general corrosion rates with an added corrosion allowance suggests that a 3.2- to 6.4-mm-thick wall may have a life of 1000 yr. Pitting and crevice corrosion are not likely corrosion modes in basalt ground waters. It is also unlikely that stress corrosion cracking (SCC) will occur in the commercially pure (CP) titanium alloy or in palladiumor molybdenum-alloyed titanium materials. Low-alloy cast irons may be used as barrier metals if the environment surrounding the metal keeps the alloy in the passive range. The solubility of the corrosion product and the semipermeable nature of the oxide film allow significant uniform corrosion over long time periods. A linear extrapolation of high-temperature corrosion rates on carbon steels and corrosion rates of cast irons in soils gives an estimated metal penetration of 51 to 64 mm after 1000 yr. A corrosion allowance of 3 to 5 times that suggests that an acceptable cast iron wall may be from 178 to 305 mm thick. Although they cannot be fully assessed, pitting and crevice corrosion should not affect cast iron due to the ground-water chemistry of basalt

70

MCC [Materials Characterization Center] corrosion tests at reference testing conditions for A27 cast steel in Hanford ground water  

International Nuclear Information System (INIS)

The corrosion of A27 cast steel in synthetic Hanford ground water was characterized by uniform wastage of the metal with no evidence of pitting or intergranular corrosion. The average corrosion rate decreased with increasing test duration which indicated that the corrosion rate for long time periods can be conservatively predicted for conditions simulated by these tests. The corrosion products for the static and flowby tests were very similar and consisted of a gel-like, very adherent, amorphous layer next to the metal with adherent packing material (basalt = bentonite) attached. The corrosion product for the air/steam tests was a very thin, asherent layer that was uniform over the specimen surfaces. No spalling was observed for periods as long as 120 days. The amount of corrosion for the air/steam tests at 3000C was very small with an average corrosion rate of 1.62 ?m/y for 120-day tests. The corrosion rate decreased with time and there was no indication of localized corrosion. A comparison of interlaboratory results for the three kinds of corrosion tests indicated that a relative large component of variability occurred between laboratories compared to smaller variations within each laboratory. For the longest tests compared, the total individual specimen relative standard deviations, including within-laboratory variations and between-laboratory variations, were 12% for the 120-day pressure vessel tests, 15% for the 300-day flowby tests, and 26% for the 1e 300-day flowby tests, and 26% for the 120-day air/steam tests

71

Microstructure, mechanical property and corrosion behavior of interpenetrating (HA + ?-TCP)/MgCa composite fabricated by suction casting  

International Nuclear Information System (INIS)

The novel interpenetrating (HA + ?-TCP)/MgCa composites were fabricated by infiltrating MgCa alloy into porous HA + ?-TCP using suction casting technique. The microstructure, mechanical properties and corrosion behaviors of the composites have been evaluated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical testing, electrochemical and immersion tests. It was shown that the composites had compact structure and the interfacial bonding between MgCa alloy and HA + ?-TCP scaffolds was very well. The ultimate compressive strength of the composites was about 500–1000 fold higher than that of the original porous scaffolds, and it still retained quarter-half of the strength of the bulk MgCa alloy. The electrochemical and immersion tests indicated that the corrosion resistance of the composites was better than that of the MgCa matrix alloy, and the corrosion products of the composite surface were mainly Mg(OH)2, HA and Ca3(PO4)2. Meanwhile, the mechanical and corrosive properties of the (HA + ?-TCP)/MgCa composites were adjustable by the choice of HA content. - Highlights: • The composites were fabricated by infiltrating MgCa alloy into porous HA + ?-TCP. • The microstructure, mechanical and corrosion properties were investigated. • It showed composites had compact structures and good interfacial bonding. • The mechanical and corrosive properties can be adjustable by the HA content. The corrosion mechanism of the composite has been explained

72

Characterization of biofilm and corrosion of cast iron pipes in drinking water distribution system with UV/Cl2 disinfection.  

Science.gov (United States)

The effect of UV/Cl2 disinfection on the biofilm and corrosion of cast iron pipes in drinking water distribution system were studied using annular reactors (ARs). Passivation occurred more rapidly in the AR with UV/Cl2 than in the one with Cl2 alone, decreasing iron release for higher corrosivity of water. Based on functional gene, pyrosequencing assays and principal component analysis, UV disinfection not only reduced the required initial chlorine dose, but also enhanced denitrifying functional bacteria advantage in the biofilm of corrosion scales. The nitrate-reducing bacteria (NRB) Dechloromonas exhibited the greatest corrosion inhibition by inducing the redox cycling of iron to enhance the precipitation of iron oxides and formation of Fe3O4 in the AR with UV/Cl2, while the rhizobia Bradyrhizobium and Rhizobium, and the NRB Sphingomonas, Brucella producing siderophores had weaker corrosion-inhibition effect by capturing iron in the AR with Cl2. These results indicated that the microbial redox cycling of iron was possibly responsible for higher corrosion inhibition and lower effect of water Larson-Skold Index (LI) changes on corrosion. This finding could be applied toward the control of water quality in drinking water distribution systems. PMID:24859195

Zhu, Ying; Wang, Haibo; Li, Xiaoxiao; Hu, Chun; Yang, Min; Qu, Jiuhui

2014-09-01

73

Systematic Microstructural and Corrosion Performance Evaluation of CK-3MCuN and CN-3MN High Molybdenum Stainless Steel Castings; FINAL  

International Nuclear Information System (INIS)

High molybdenum austenitic stainless steel castings are widely accepted for their high strength, excellent weldability, and good corrosion resistance over a wide range of temperatures in highly oxidizing aqueous and gaseous media in chemical processing and other environments. With their desirable performance, high molybdenum austenitic stainless steel castings are increasingly applied in industry in a similar manner as wrought materials. In general, cast and wrought stainless and high alloy steels are anticipated to possess equivalent resistance to corrosive media, and they are frequently used in conjunction with each other. However, alloying element segregation usually is more evident in castings than in wrought counterparts. Segregation of alloying elements can lead to the formation of secondary phases, such as sigma. Mechanical properties and especially the corrosion resistance of castings may be affected by the secondary phases. In addition, improper heat treatment procedures c an also lead to the formation of carbides and secondary phases in high alloy and austenitic stainless steels

74

Blood microvascular organization of the nasal-associated lymphoid tissue of the guinea pig: a scanning electron microscopic study of corrosion casts.  

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Full Text Available It has previously been confirmed that the guinea pig has aggregations of 10-20 lymphoid follicles at the junction of the nasal cavity and the nasopharyngeal duct. The vascular architecture of this nasal-associated lymphoid tissue (NALT was studied by the corrosion cast/scanning electron microscope method. The NALT was supplied by branches of the inferior nasal artery. These afferent arterial branches gave off arterioles to the follicles and the interfollicular regions, where the arterioles ramified into capillaries. Some of these arterioles reached the subepithelial region to form a single-layer dense capillary network. The subepithelial capillaries gathered into short collecting venules, which in turn drained into high endothelial venules (HEV in the interfollicular region. The HEV, which also receives tributaries from the follicular and interfollicular capillary plexuses, descended in the interfollicular regions and finally flowed into the efferent veins at the bottom of the NALT. Indentations impressed by high endothelial cells (HEC were prominent on the surface of the HEV casts, and their frequency was larger in the upper course or segments than in the lower. This suggests that the incidence of HEC in the upper segments is higher than in the lower segments, and these findings are consistent with the hypothesis that some substances which are taken up into the subepithelial capillaries and transported to the venules induce differentiation and maintain of HEVs.

Okada,Satoko

1995-08-01

75

Corrosion inhibition of Eleusine aegyptiaca and Croton rottleri leaf extracts on cast iron surface in 1 M HCl medium  

Science.gov (United States)

The adsorption and corrosion inhibition activities of Eleusine aegyptiaca (E. aegyptiaca) and Croton rottleri (C. rottleri) leaf extracts on cast iron corrosion in 1 M hydrochloric acid solution were studied first time by weight loss and electrochemical techniques viz., Tafel polarization and electrochemical impedance spectroscopy. The results obtained from the weight loss and electrochemical methods showed that the inhibition efficiency increased with inhibitor concentrations. It was found that the extracts acted as mixed-type inhibitors. The addition of halide additives (KCl, KBr, and KI) on the inhibition efficiency has also been investigated. The adsorption of the inhibitors on cast iron surface both in the presence and absence of halides follows the Langmuir adsorption isotherm model. The inhibiting nature of the inhibitors was supported by FT-IR, UV-vis, Wide-angle X-ray diffraction and SEM methods.

Rajeswari, Velayutham; Kesavan, Devarayan; Gopiraman, Mayakrishnan; Viswanathamurthi, Periasamy; Poonkuzhali, Kaliyaperumal; Palvannan, Thayumanavan

2014-09-01

76

Corrosion behaviour of some cast stainless steels and high alloy white irons in scrubber solutions of flue gas desulfurization plants  

International Nuclear Information System (INIS)

Weight loss and electrochemical measurements have been used to determine the ranges of applicability of cast austenitic stainless steel Werkstoff No. 1.4408, of two special cast ferritic-austenitic stainless steels NORIDUR 9.4460 and NORICLOR NC 246 and of two high alloy Cr and CrMo white irons in scrubber solutions of Flue Gas Desulfurization (FGD) plants. Whereas the Werkstoff No. 1.4408 cannot be used due to its insufficient resistance to general and localized corrosion, NORIDUR 9.4460 can be used in scrubber solutions with pH > 2.5 and chloride concentrations up to 80 g/l, NORICLOR NC 246 with 5% Mo even in liquids with pH > 1.5 and chlorides up to 100 g/l. At lower pH-values both duplex stainless steels show active corrosion of either the austenite or the ferrite depending on the contents of hydrochloric acid in the solution. At higher chloride concentrations pitting occurs on the passive materials. The CrMo white iron NORILOY NL 252 with 25% Cr and 2% Mo can be used in scrubber liquids with pH > 3.5. As the ferritic matrix is cathodically protected by the precipitated carbides, there is no sensitivity of this alloy to chlorides. In liquids with pH < 3.5 there is selective corrosion of the ferritic matrix. For practical application of all these cast alloys the limits for purely corrosive attack have to be modified to assure resistance to a superposition of corrosion, erosion/abrasion and cavitation on parts exposed to real flow conditions in FGD scrubbers. (orig.l flow conditions in FGD scrubbers. (orig.)

77

Effect of sulfate on the transformation of corrosion scale composition and bacterial community in cast iron water distribution pipes.  

Science.gov (United States)

The chemical stability of iron corrosion scales and the microbial community of biofilm in drinking water distribution system (DWDS) can have great impact on the iron corrosion and corrosion product release, which may result in "red water" issues, particularly under the situation of source water switch. In this work, experimental pipe loops were set up to investigate the effect of sulfate on the dynamical transformation characteristics of iron corrosion products and bacterial community in old cast iron distribution pipes. All the test pipes were excavated from existing DWDS with different source water supply histories, and the test water sulfate concentration was in the range of 50-350 mg/L. Pyrosequencing of 16S rRNA was used for bacterial community analysis. The results showed that iron release increased markedly and even "red water" occurred for pipes with groundwater supply history when feed water sulfate elevated abruptly. However, the iron release of pipes with only surface water supply history changed slightly without noticeable color even the feed water sulfate increased multiply. The thick-layered corrosion scales (or densely distributed tubercles) on pipes with surface water supply history possessed much higher stability due to the larger proportion of stable constituents (mainly Fe3O4) in their top shell layer; instead, the rather thin and uniform non-layered corrosion scales on pipes with groundwater supply history contained relatively higher proportion of less stable iron oxides (e.g. ?-FeOOH, FeCO3 and green rust). The less stable corrosion scales tended to be more stable with sulfate increase, which was evidenced by the gradually decreased iron release and the increased stable iron oxides. Bacterial community analysis indicated that when switching to high sulfate water, iron reducing bacteria (IRB) maintained dominant for pipes with stable corrosion scales, while significant increase of sulfur oxidizing bacteria (SOB), sulfate reducing bacteria (SRB) and iron oxidizing bacteria (IOB) was observed for pipes with less stable corrosion scales. PMID:24784453

Yang, Fan; Shi, Baoyou; Bai, Yaohui; Sun, Huifang; Lytle, Darren A; Wang, Dongsheng

2014-08-01

78

Corrosion behaviour of the AlSi6Cu4 alloy and cast AlSi6Cu4-graphite particles composite  

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Full Text Available The corrosion behaviour of the AlSi6Cu4 alloy as a composite matrix and of composites with 8% vol. of graphite particles was investigated. The corrosion experiments were performed over a range of elevated temperatures and were carried out in sea water (3.5%NaCl solution. We have focused our attention to the determination of the mode of corrosion attack and to the determination of the rate ofcorrosion and other corrosion characteristics. Both as-cast and annealed matrix and composite specimens were tested, as well as the99.9% as-cast aluminium for comparison. Corrosion behaviour of the materials was assessed by the corrosion potential (Ec and bypotentiodynamic (polarization curves. As expected, composite is less corrosion resistant than the matrix alloy. In addition to pitting,a severe galvanic corrosion occurs as a result of galvanic couple aluminium/graphite formation. Corrosion potentials imply that examinedmaterials would be sufficiently resistant in non or slightly oxidizing solutions without dissolved oxygen. All studied materials corrode very slowly at potentials negative to corrosion potential, while at potentials positive to corrosion potential the corrosion rate goes up by 1 or 2 orders.

S. Holecek

2009-04-01

79

Microstructure, mechanical property and corrosion behavior of co-continuous ?-TCP/MgCa composite manufactured by suction casting  

International Nuclear Information System (INIS)

Highlights: • The novel co-continuous ?-TCP/MgCa composite was fabricated using suction casting technique. • The microstructure, mechanical and corrosion properties of the composite were investigated. • It showed the composite had compact structure and good interfacial combination. • The ultimate compressive strength of the composite was near with the natural bone. • And the corrosion resistance of the composite was better than that of the MgCa bulk alloy. - Abstract: The co-continuous ?-TCP/MgCa composite was fabricated by infiltrating MgCa alloy into porous ?-TCP using suction casting technique. The microstructure, mechanical property and corrosion behaviors of the composite have been evaluated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical testing, electrochemical and immersion tests. It was shown that the composite structure was compact and the interfacial combination between MgCa alloy and ?-TCP scaffold was very well. The composite had an ultimate compressive strength of (147 ± 13) MPa, which was near with the natural bone (2–180 MPa) and about 1000-fold higher than that of the original porous ?-TCP scaffold, but it still retained over half of the strength of the MgCa bulk alloy. The electrochemical and immersion tests indicated that the corrosion resistance of the composite was better than that of the MgCa bulk alloy, and the corrosion rate of the MgCa matrix alloy was quicker than that of the porous scaffold for the composite. The corrosion products of the composite surface were mainly Mg(OH)2, hydroxyapatite (HA) and Ca3(PO4)2

80

Galvanic corrosion of copper-cast iron couples in relation to the Swedish radioactive waste canister concept  

Energy Technology Data Exchange (ETDEWEB)

To ensure the safe encapsulation of spent nuclear fuel rods for geological disposal, SKB are considering using the Copper-Iron Canister, which consists of an outer copper canister and an inner cast iron container. The canister will be placed into boreholes in the bedrock of a geologic repository and surrounded by bentonite clay. In the unlikely event of the outer copper canister being breached, water could enter the annulus between the inner and outer canister and at points of contact between the two metals there would be a possibility of galvanic interactions. To study this effect, copper-cast iron galvanic couples were set up in a number of different environments representing possible conditions in the SKB repository. The tests investigated two artificial pore-waters and a bentonite slurry, under aerated and deaerated conditions, at 30 deg. C and 50 deg. C. The currents passing between the coupled electrodes and the potential of the couples were monitored for several months. In addition, some bimetallic crevice specimens based on the multi-crevice assembly (MCA) design were used to simulate the situation where the copper canister will be in direct contact with the cast iron inner vessel. The effect of growing an oxide film on the surface of the cast iron prior to coupling it with copper was also investigated. The electrochemical results are presented graphically in the form of electrode potentials and galvanic corrosion currents as a function of time. The galvanic currents in aerated conditions were much higher than in deaerated conditions. For example, at 30 deg. C, galvanic corrosion rates as low as 0.02 {mu}m/year were observed for iron in groundwater after de-aeration, but of the order of 100 {mu}m/year for the cast iron at 50 deg. C in the presence of oxygen. The galvanic currents were generally higher at 50 deg. C than at 30 deg. C. None of the MCA specimens exhibited any signs of crevice corrosion under deaerated conditions. It will be shown that in deaerated conditions the galvanic corrosion rates of iron coupled to copper are close to the values observed for anaerobic corrosion rates of uncoupled iron. The results from the work presented in the paper will be discussed in relation to understanding the evolution of the environment within the annulus of the SKB canister if premature failure of the outer copper canister were to occur. (authors)

Smart, N.R.; Fennell, P.A.H.; Rance, A.P. [Serco Assurance, Culham Science Centre, Abingdon, Oxfordshire, OX14 3ED (United Kingdom); Werme, L.O. [SKB, Box 5864, SE-10240, Stockholm (Sweden)

2004-07-01

 
 
 
 
81

Influence of Electrolytic Plasma Oxidation Coating on Tensile Behavior of Die-Cast AM50 Alloy Subjected to Salt Corrosion  

Science.gov (United States)

Three different thickness ceramic coatings were deposited on die-cast AM50 magnesium alloy in KOH and NaAlO2 solution using electrolytic plasma oxidation (EPO) technology for corrosion prevention. Immersion corrosion tests were carried out in 3.5% NaCl solution for 336 hours to investigate the effect of coating thicknesses on tensile and fracture behaviors of the coated AM50 alloys. The results show that the yield strength (YS) and ultimate tensile strength (UTS) of the coated AM50 alloy subjected to immersion corrosion increase with an increase in coating thicknesses. Further analyses on stress and strain curves indicate that the coating enhances the strain-hardening rates of the corroded alloy during its plastic deformation. SEM examination on the fractured surface manifests that the substrate AM50 alloys exhibit characteristics of ductile deformation with deep dimples. However, brittle features prevail on the fractured surface of the mixed layer of coating plus oxidation corrosion product. Micro cracks were observed between the mixed layer and the AM50 alloy substrate induced by corrosion and within the mixed layer induced by EPO process, which could be responsible for the brittle fracture.

Han, Lihong; Nie, Xueyuan; Zhang, Peng; Zhang, Qiang; Hu, Henry

82

Corrosion behaviour of the AlSi6Cu4 alloy and cast AlSi6Cu4-graphite particles composite  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The corrosion behaviour of the AlSi6Cu4 alloy as a composite matrix and of composites with 8% vol. of graphite particles was investigated. The corrosion experiments were performed over a range of elevated temperatures and were carried out in sea water (3.5%NaCl solution). We have focused our attention to the determination of the mode of corrosion attack and to the determination of the rate ofcorrosion and other corrosion characteristics. Both as-cast and annealed matrix and composite specimen...

Holecek, S.; Nadolski, M.; Konopka, Z.; Lagiewka, M.; Pozar, J.; Zyska, A.

2009-01-01

83

Effect of N addition on tensile and corrosion behaviors of CD4MCU cast duplex stainless steels  

Science.gov (United States)

The effect of N addition on the microstructure, tensile, and corrosion behaviors of CD4MCU (Fe-25Cr-5Ni-2.8Cu-2Mo) cast duplex stainless steel was examined in the present study. The slow strain rate tests were also conducted at a nominal strain rate of 1 × 10-6/s in air and 3.5 pct NaCl+5 pct H2SO4 solution for studying the stress corrosion cracking (SCC) behavior. It was observed that the volume fraction of austenitic phase in CD4MCU alloy varied from 38 to 59 pct with increasing nitrogen content from 0 to 0.27 wt. pct. The tensile behavior of CD4MCU cast duplex stainless steels, which tended to vary significantly with different N contents, appeared to be strongly related to the volume changes in ferritic and austenitic phases, rather than the intrinsic N effect. The improvement in the resistance to general corrosion in 3.5 pct NaCl+5 pct H2SO4 aqueous solution was notable with 0.13 pct N addition. The further improvement was not significant with further N addition. The resistance to SCC of CD4MCU cast duplex stainless steels in 3.5 pct NaCl+5 pct H2SO4 aqueous solution, however, increased continuously with increasing N content. The enhancement in the SCC resistance was believed to be related to the volume fraction of globular austenitic colonies, which tended to act as barriers for the development of initial pitting cracks in the ferritic phase into the sharp ones.

Son, Jinil; Kim, Sangshik; Lee, Jehyun; Choi, Byunghak

2003-08-01

84

Effects of Ce addition on microstructure, mechanical properties and corrosion resistance of as-cast AZ80 magnesium alloy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study, Ce was introduced into the AZ80 alloy and the effects of Ce addition on the microstructure, mechanical properties and corrosion resistance of the as-cast AZ80 magnesium alloy were investigated. The results show that the addition of Ce into the AZ80 alloy can not only refine the microstructure, but also result in the formation of the needle-like Al4Ce phase. These tiny Al4Ce phases are homogeneously distributed at grain boundaries and within grains. An appropriate Ce addition c...

Wang Wei; Xu Chunxiang; Zhang Jinshan

2014-01-01

85

Structural aspects of corrosion resistance in alloys based on the Fe3Al intermetallic phase in the cast state  

Science.gov (United States)

This paper presents the results of investigation of four cast alloys based on the Fe3Al intermetallic phase. Microstructure tests using light microscopy, electron scanning microscopy and X-ray diffraction methods, have been performed. On this basis, a presence of particles rich in zirconium and molybdenum, and in case of the alloy with 28 at.% aluminium and 5 at.% chromium — the presence of sigma phase (FeCr), has been found. Also, the results of the study of the microstructure influence on the electrochemical corrosion resistance in the 5 % NaCl solution have been presented. The Fe-26Al-2Cr-1Mo-0.1Zr-0.005B at.% and Fe-26Al-5Cr-1Mo-0.1Zr-0.005B at.% alloys exhibited increased corrosion resistance in comparison to the Fe-23Al-1Mo-0.1Zr-0.005B at.% alloy without chromium addition. The appearance of the sigma phase in the alloy of Fe-28Al-5Cr-1Mo-0.1Zr-0.005B at.% chemical composition resulted in lowering the corrosion resistance of this alloy and a change in corrosion character from the pitting to the intercrystalline one.

Lachowicz, M. M.; Haimann, K.; Lachowicz, M. B.; Jasionowski, R.; Pawlak, S.

2012-09-01

86

Investigations of high-temperature corrosion of Cr-Ni cast steel  

Directory of Open Access Journals (Sweden)

Full Text Available Austenitic cast steels of Cr25-Ni32-Nb grade have found wide application in chemical and petrochemical industries. This study discusses the problem of the kinetics of oxidation of these materials in the atmosphere of laboratory air at temperatures of 930 and 1000 °C. Considering the operating conditions of castings (centrifugally cast reformer tubes, the results of the oxidation test of specimens taken from the zone of columnar crystals and equiaxial grains were presented.

R. Zapa?a

2009-07-01

87

Investigations of high-temperature corrosion of Cr-Ni cast steel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Austenitic cast steels of Cr25-Ni32-Nb grade have found wide application in chemical and petrochemical industries. This study discusses the problem of the kinetics of oxidation of these materials in the atmosphere of laboratory air at temperatures of 930 and 1000 °C. Considering the operating conditions of castings (centrifugally cast reformer tubes), the results of the oxidation test of specimens taken from the zone of columnar crystals and equiaxial grains were presented.

Zapa?a, R.; Kalandyk, B.

2009-01-01

88

Energy Saving Melting and Revert Reduction (E-SMARRT): Optimization of Heat Treatments on Stainless Steel Castings for Improved Corrosion Resistance and Mechanical Properties  

Energy Technology Data Exchange (ETDEWEB)

It is commonly believed that high alloy steel castings have inferior corrosion resistance to their wrought counterparts as a result of the increased amount of microsegregation remaining in the as-cast structure. Homogenization and dissolution heat treatments are often utilized to reduce or eliminate the residual microsegregation and dissolve the secondary phases. Detailed electron probe microanalysis (EPMA) and light optical microscopy (LOM) were utilized to correlate the amount of homogenization and dissolution present after various thermal treatments with calculated values and with the resultant corrosion resistance of the alloys.The influence of heat treatment time and temperature on the homogenization and dissolution kinetics were investigated using stainless steel alloys CN3MN and CK3MCuN. The influence of heat treatment time and temperature on the impact toughness and corrosion reistance of cast stainless steel alloys CF-3, CF-3M, CF-8, and CF-8M was also investigated.

John N. DuPont; Jeffrey D. Farren; Andrew W. Stockdale; Brett M. Leister

2012-06-30

89

APPLIED 3-DANATOMY OF LIVER BILE DUCTS IN INJECTION CORROSION CASTS  

Directory of Open Access Journals (Sweden)

Full Text Available On the 20 post-autopsy adult isolated liver specimens of patients of both sexes (17 male and 3female aged 29–88, the injection-corrosion method was used. Colored acrylate was injected into the biliary system, and uncolored acrylate into the portal vein. A total of 17 acrylate casts were of proper quality.Within the 9 portal segments, both the anatomical determination and quantity and the mode of confluence of intrahepatic bile ducts were established. Different modes of biliary tract confluence up to the sectors and hepatics were found. Besides the most frequent findings of conventionally confluence bile ducts, there were aberrant modalities of biliary drainage in eight cases. Among them 5 cases had confluence of posterior and anterior sector ducts in the left hepatic duct and 1 case had confluence at first of anterior and then posterior sector ducts in the left hepatic duct. Also, extrahilar connection of the right posterior with left lateral into common hepatic duct, where the latter entered themedial and anterior sectors ducts in1 case was found. There was a subsequent confluence of ducts from the 8th and 5th segments in 1 case, and from the lateral andmedial sectorswith or without caudate lobe in 3 cases. A common (4 or separate (2 confluence of left and right portions ducts in the left drainage system were in 6 cases, whereas in both, the left and right drainage system in 7 cases was found. Rare, there wasan aberrant single channel from the right portion in 1 case, as well as the presence and biliary drainage only of the left portion of 1st segment was found. Segment 9 bile ducts drained all three subsegments (b, c and d in 10 cases, and only two (c and d in 3 cases, as well as only two (c and b of present three subsegments in 3 cases. Also, there was even one case with present 9d subsegment and without 9th segment duct. Those modalities are of interest in an applying and accurate interpretation and performance of diagnostic and interventional procedures, as well as in segmental, sectoral or hemihepatic resection in liver surgery.

Jurkovikj Dragica M.

2013-01-01

90

Microstructure and corrosion behavior of die-cast AM60B magnesium alloys in a complex salt solution: A slow positron beam study  

Energy Technology Data Exchange (ETDEWEB)

The microstructure and corrosion behavior of high pressure die-cast (HPDC) and super vacuum die-cast (SVDC) AM60B magnesium alloys were investigated in a complex salt solution using slow positron beam technique and potentiodynamic polarization tests. The experiments revealed that a CaCO3 film was formed on the surface of the alloys and that the rate of CaCO3 formation for the SVDC alloy with immersion time was slower than that of the HPDC alloy. The larger volume fraction of b-phase in the skin layer of the SVDC alloy than that of the HPDC alloy was responsible for the better corrosion resistance.

Liu, Y.F. [Wuhan University; Qin, Q.L. [Wuhan University; Yang, W. [Wuhan University; Wen, W. [University of Kentucky; Zhai, T. [University of Kentucky; Yu, B. [University of Alberta; Liu, D.Y. [University of Alberta; Luo, A. [GM Research and Development Center; Song, GuangLing [ORNL

2014-01-01

91

Effects of Ce addition on microstructure, mechanical properties and corrosion resistance of as-cast AZ80 magnesium alloy  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, Ce was introduced into the AZ80 alloy and the effects of Ce addition on the microstructure, mechanical properties and corrosion resistance of the as-cast AZ80 magnesium alloy were investigated. The results show that the addition of Ce into the AZ80 alloy can not only refine the microstructure, but also result in the formation of the needle-like Al4Ce phase. These tiny Al4Ce phases are homogeneously distributed at grain boundaries and within grains. An appropriate Ce addition can also change the ?-Mg17Al12 phase at the grain boundaries from continuous network to small island-like. At the same time, with the increase of Ce content from 0 to 2.0wt.%, the macro-hardness of the as-cast alloy is enhanced linearly, while impact toughness, tensile strength and elongation all firstly increase and then decrease. The AZ80 alloy containing 1.0wt.% Ce exhibits the optimal properties. Its macro-hardness, impact toughness, tensile strength and elongation are 61.90 HB, 15.50 J·cm-2, 171.80 MPa and 3.35%, increase by 9.95%, 63%, 13.3% and 36.7%, respectively compared with the base alloy. In addition, Ce can enhance the corrosion resistance of the AZ80 magnesium alloy.

Wang Wei

2014-05-01

92

Effect of cerium addition on microstructure and corrosion resistance of die cast AZ91 magnesium alloy  

Energy Technology Data Exchange (ETDEWEB)

A novel AZ91 Ce containing magnesium alloy characterized by excellent corrosion resistance is fabricated by adding rare earth Ce (cerium) in the form of a Mg-Ce master alloy. The metallographic investigation shows that Ce added to AZ91 can obviously decrease the size of {beta}-Mg{sub 17}Al{sub 12} and forms Al{sub 11}Ce{sub 3} intermetallic compounds in the shape of fine needles. The corrosion tests and electrochemical measurements indicate that the corrosion resistance of AZ91 Ce containing magnesium alloy is obviously higher than that of AZ91. Furthermore, increasing the content of Ce in the magnesium alloy can further enhance the corrosion resistance. X-ray photoelectron spectroscopy (XPS) reveals that Ce can be incorporated into corrosion products in the form of CeO{sub 2} in the course of corrosion. Based on the preliminary analysis, the addition of Ce can improve the corrosion resistance of AZ91 by decreasing the size of {beta}-Mg{sub 17}Al{sub 12} and enhancing the protective effectiveness of corrosion products. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

Song, Y.L.; Liu, Y.H.; Wang, S.H.; Yu, S.R.; Zhu, X.Y. [Key Laboratory of Automobile Materials of Ministry of Education and Department of Materials Science and Engineering, Jilin University, No.5988 Renmin Street, Changchun 130025 (China)

2007-03-15

93

Influence of rare earth Y on the corrosion behavior of as-cast AZ91 alloy  

International Nuclear Information System (INIS)

The influence of different contents of rare earth Y on the corrosion resistance of AZ91 alloy was investigated by the salt spray test and electrochemical measurements. It was found that the proper amount of Y was effective on improving the corrosion resistance of AZ91 alloy. The optimal modification effect was obtained when the Y content in the alloys was 0.3 wt.%. However, with the increase of rare earth Y, the corrosion rate became bigger slightly, and further addition of Y content over 0.3 wt.% resulted in the increment of the corrosion rate. It is suggested that the excessive rare earth Y can reduce the corrosion resistance of AZ91 alloy.

94

Influence of rare earth Y on the corrosion behavior of as-cast AZ91 alloy  

Energy Technology Data Exchange (ETDEWEB)

The influence of different contents of rare earth Y on the corrosion resistance of AZ91 alloy was investigated by the salt spray test and electrochemical measurements. It was found that the proper amount of Y was effective on improving the corrosion resistance of AZ91 alloy. The optimal modification effect was obtained when the Y content in the alloys was 0.3 wt.%. However, with the increase of rare earth Y, the corrosion rate became bigger slightly, and further addition of Y content over 0.3 wt.% resulted in the increment of the corrosion rate. It is suggested that the excessive rare earth Y can reduce the corrosion resistance of AZ91 alloy.

Luo, T.J. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Yang, Y.S. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)], E-mail: ysyang@imr.ac.cn; Li, Y.J.; Dong, X.G. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

2009-11-01

95

Comparative analysis of the behavior to corrosion of forged and cast austenitic stainless steel when used in a surgical prosthesis  

International Nuclear Information System (INIS)

The selection of a material to be used in implants involves tests that cover aspects relative to its resistance to corrosion and its bio-compatibility. Testing the material implanted in the human body is a very difficult process or it is impossible via direct electrochemistry. Because of this laboratory tests have been developed that simulate the natural setting of the material in the organism using saline solutions that are kept at 37oC and pH 7.4. The material that is to be used should be resistant to corrosion in the body so that ions are not released into the organism and the device should maintain its integrity in service and not to suffer degradation. This work compares the behavior to corrosion of samples of a cast prosthesis (lower tibia, made of stainless steel ACI CF 3M) and a forged prosthesis (femorals, made of stainless steel ASTM F 621) with laminated bars of the same quality (stainless steel ASTM F 138). The samples were characterized with physical and electrochemical tests under three different thermal conditions: solubilized, annealed and forged or cast. The test pieces were submitted to electrochemical direct current tests during their immersion in a 0.9% deoxygenated NaCl solution and thermostatisized at 37oC. The Cr and Fe content in solution at the end of the electrochemical test was evaluated together with the micro hardness of the material and the characterization of the final stage of the material was carried out by optic of the material was carried out by optic microscopy and sweep electronics (CW)

96

Wear and Corrosion Resistance of Fe Based Coatings by HVOF Sprayed on Gray Cast-Iron for Automotive Application  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, commercially available FeSiNiCr and FeBCr alloy powders were designed with suitable compositions, gas atomized and then coated on gray cast-iron substrate. The microstructures of the feed stock Fe based alloy powders and the coatings were investigated by means of optical microscopy (OM, X-Ray diffraction (XRD, Thermogravimetric analysis (TGA and Scanning Electron Microscopy (SEM. In the present study, both the coating materials experienced two-body wear mechanisms. The results showed that for loads of 0.05 N, 0.1 N and 0.2 N, the wear resistance of FeBCr coating was less than FeSiNiCr by 44 %, 40 % and 31 %, respectively. The results indicated that the coated substrates exhibited lower corrosion current densities and lower corrosion rates, when placed in 20 wt.% H2SO4 solutions. In addition, the use of optimal spraying parameters/conditions gave improvements to the corrosion resistance of the substrates that had been treated with the crystalline coating.

M.S. Priyan

2014-12-01

97

Corrosion  

Science.gov (United States)

Presents some materials for use in demonstration and experimentation of corrosion processes, including corrosion stimulation and inhibition. Indicates that basic concepts of electrochemistry, crystal structure, and kinetics can be extended to practical chemistry through corrosion explanation. (CC)

Slabaugh, W. H.

1974-01-01

98

Rapid casting of patterned vascular networks for perfusable engineered three-dimensional tissues  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the absence of perfusable vascular networks, three-dimensional (3D) engineered tissues densely populated with cells quickly develop a necrotic core. Yet the lack of a general approach to rapidly construct such networks remains a major challenge for 3D tissue culture. Here, we printed rigid 3D filament networks of carbohydrate glass, and used them as a cytocompatible sacrificial template in engineered tissues containing living cells to generate cylindrical networks that could be lined with ...

Miller, Jordan S.; Stevens, Kelly R.; Yang, Michael T.; Baker, Brendon M.; Nguyen, Duc-huy T.; Cohen, Daniel M.; Toro, Esteban; Chen, Alice A.; Galie, Peter A.; Yu, Xiang; Chaturvedi, Ritika; Bhatia, Sangeeta N.; Chen, Christopher S.

2011-01-01

99

Effect of yttrium-rich misch metal on the microstructures, mechanical properties and corrosion behavior of die cast AZ91 alloy  

International Nuclear Information System (INIS)

Die cast AZ91-xYmm (x = 0-0.8 wt.%) magnesium alloys with excellent tensile properties and corrosion resistance behavior were successfully prepared by a simple addition of yttrium-rich misch metal (Ymm) to AZ91. Influences of Ymm on the microstructure, mechanical properties and corrosion behavior of AZ91 were investigated. The results showed that addition of Ymm to die cast AZ91 alloy could refine the microstructure including primary ?-Mg and eutectic ?-Mg17Al12. When the content of Ymm reached 0.8 wt.% a small quantity of Al2Y phase would form. The tensile properties were improved greatly with addition of Ymm to AZ91. The creep rate of the AZ91-Ymm alloys, tested at 150 deg. C/50 MPa, was one order of magnitude lower than that of AZ91. When addition of Ymm was more than 0.3 wt.%, the salt-spray corrosion resistance of AZ91-Ymm alloys could be 30-40 times of that of AZ91. The improvement of corrosion resistance with addition of Ymm was confirmed by the results of electrochemical polarization experiments. Mechanism of the improvement of mechanical properties and corrosion behavior caused by Ymm was also discussed

100

Effect of yttrium-rich misch metal on the microstructures, mechanical properties and corrosion behavior of die cast AZ91 alloy  

Energy Technology Data Exchange (ETDEWEB)

Die cast AZ91-xYmm (x = 0-0.8 wt.%) magnesium alloys with excellent tensile properties and corrosion resistance behavior were successfully prepared by a simple addition of yttrium-rich misch metal (Ymm) to AZ91. Influences of Ymm on the microstructure, mechanical properties and corrosion behavior of AZ91 were investigated. The results showed that addition of Ymm to die cast AZ91 alloy could refine the microstructure including primary {alpha}-Mg and eutectic {beta}-Mg{sub 17}Al{sub 12}. When the content of Ymm reached 0.8 wt.% a small quantity of Al{sub 2}Y phase would form. The tensile properties were improved greatly with addition of Ymm to AZ91. The creep rate of the AZ91-Ymm alloys, tested at 150 deg. C/50 MPa, was one order of magnitude lower than that of AZ91. When addition of Ymm was more than 0.3 wt.%, the salt-spray corrosion resistance of AZ91-Ymm alloys could be 30-40 times of that of AZ91. The improvement of corrosion resistance with addition of Ymm was confirmed by the results of electrochemical polarization experiments. Mechanism of the improvement of mechanical properties and corrosion behavior caused by Ymm was also discussed.

Zhang Jinghuai [State Key Laboratory of Rare Earth Resources Application, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of the Chinese Academy of Science, Beijing 100049 (China); Niu Xiaodong; Qiu Xin [State Key Laboratory of Rare Earth Resources Application, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Liu Ke [State Key Laboratory of Rare Earth Resources Application, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of the Chinese Academy of Science, Beijing 100049 (China); Nan Changming [Shanxi Wenxi Yinguang Magnesium Group, Shanxi 043800 (China); Tang Dingxiang [State Key Laboratory of Rare Earth Resources Application, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Meng Jian [State Key Laboratory of Rare Earth Resources Application, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)], E-mail: jmeng@ciac.jl.cn

2009-03-05

 
 
 
 
101

Subsurface microstructural changes in a cast heat resisting alloy caused by high temperature corrosion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A cast HP ModNb alloy (Fe–25Cr–35Ni–1Nb, wt.%) was oxidised and carburised in CO–CO2 corresponding to aC = 0.1 and pO2 = 3 1016 atm at 1080 C. Formation of an external, chromium-rich oxide scale led to depletion of this metal in a deep alloy subsurface zone. Within that zone, secondary chromium-rich carbides dissolved, primary carbides oxidised, solute silicon and aluminium internally oxidised, and extensive porosity developed. Pore volumes correspond to the difference be...

Oquab, Djar; Xu, Nan; Monceau, Daniel; Young, David

2010-01-01

102

Corrosion and protection of heterogeneous cast Al-Si (356) and Al-Si-Cu-Fe (380) alloys by chromate adn cerium inhibitors  

Science.gov (United States)

In this study, the localized corrosion and conversion coating on cast alloys 356 (Al-7.0Si-0.3Mg) and 380 (Al-8.5Si-3.5Cu-1.6Fe) were characterized. The intermetallic phases presence in the permanent mold cast alloy 356 are primary-Si, Al5FeSi, Al8Si6Mg3Fe and Mg2Si. The die cast alloy 380 is rich in Cu and Fe elements. These alloying elements result in formation of the intermetallic phases Al 5FeSi, Al2Cu and Al(FeCuCr) along with primary-Si. The Cu- and Fe-rich IMPS are cathodic with respect to the matrix phase and strongly govern the corrosion behavior of the two cast alloys in an aggressive environment due to formation of local electrochemical cell in their vicinity. Results have shown that corrosion behavior of permanent mould cast alloy 356 is significantly better than the die cast aluminum alloy 380, primarily due to high content of Cu- and Fe-rich phases such as Al2Cu and Al 5FeSi in the latter. The IMPS also alter the protection mechanism of the cast alloys in the presence of inhibitors in an environment. The presence of chromate in the solution results in reduced cathodic activity on all the phases. Chromate provides some anodic inhibition by increasing pitting potentials and altering corrosion potentials for the phases. Results have shown that performance of CCC was much better on 356 than on 380, primarily due to inhomogeneous and incomplete coating deposition on Cu- and Fe- phases present in alloy 380. XPS and Raman were used to characterize coating deposition on intermetallics. Results show evidence of cyanide complex formation on the intermetallic phases. The presence of this complex is speculated to locally suppress CCC formation. Formation and breakdown of cerium conversion coatings on 356 and 380 was also analyzed. Results showed that deposition of cerium hydroxide started with heavy precipitation on intermetallic particles with the coatings growing outwards onto the matrix. Electrochemical analysis of synthesized intermetallics compounds in the presence of soluble cerium cations showed that of anodic and cathodic activity was not as strongly inhibited as was observed for chromate ions. Overall cerium conversion coating showed good performance on Al-Si (356) ally, but poor performance on Fe- and Cu-rich alloy (380).

Jain, Syadwad

103

Radiographic aspects and angioarchitectural arrangements in corrosion casts of the blood supply to the human sternocleidomastoid muscle by the sternocleidomastoid branch of the occipital artery / Aspectos radiográficos e da microvasculatura do músculo esternocleidomastóideo pelo pelo ramo da artéria occipital  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A contribuição do ramo esternocleidomastóideo da artéria occipital para a irrigação do músculo esternocleidomastóideo foi avaliada em cadáveres humanos não fixados, através da injeção de contraste radiográfico e de resina polimerizável para estudo da microvasculatura. O músculo foi dividido nos terç [...] os superior, médio e inferior, a partir da sua inserção no processo mastóideo do osso temporal. Na maioria dos músculos, o pedículo superior apresentou-se formado por dois ramos paralelos longitudinais. Em todos os casos, o contraste radiográfico atingiu ou ultrapassou a parte média do músculo. Na parte mais distal do terço inferior, há pouca ou nenhuma contribuição do pedículo superior para a irrigação dessa região muscular sugerindo a contribuição de outros vasos para a sua irrigação. Os modelos de corrosão demonstraram a presença de uma profusa rede vascular no interior do músculo. Abstract in english The contribution of the sternocleidomastoid branch of the occipital artery (superior arterial pedicle - SAP) to the irrigation of the sternocleidomastoid muscle (SCM) was evaluated in fresh human cadavers by injecting radiological dye and a resin for microvasculature corrosion casts. From its insert [...] ion in the mastoid process of the temporal bone, the SCM was divided into superior, medium, and inferior thirds. In most of the SCM, The SAP are formed by two longitudinal parallel branches. In all specimens, the radiological dye injected into the SAP reached or trespassed the middle part of the studied SCM. The SAP was poorly distributed in the lowermost region of the inferior third of the SCM, suggesting the contribution of other arteries or pedicles. The corrosion casts of the microvasculature showed a profuse network of microscopic vessels in those levels where the SAP was detected.

Luis Bernardo, Fróes; Erasmo Magalhães Castro de, Tolosa; Roberto de Souza, Camargo; Eduardo, Pompeu; Edson Aparecido, Liberti.

1999-08-01

104

Corrosion/erosion of alumina-graphite composite refractories in continuous casting of steel  

International Nuclear Information System (INIS)

New compositions in alumina, graphic , silicon nitride and flux were prepared to develop state of the art alumina-graphite composite refractories. Effect of time on the dissolution of these refractories were studied. It was found that flux and nitride bonding also effect the life of alumina-graphite composite refractories. The composite refractories were subjected to steel up to 1600 degree centigrade for the determination of corrosion/erosion of these refractories. The free formation energy can be use as a relative measure of stability of oxides. The silica in the binder phase is reduced by carbon from the melt to yield silicon and carbon mono-oxide gas. Silica particles present in the refractory are dissolved initially to cause further dissolution of the refractory phase. It causes an increase in the silicon level in the melt and the carbon level of low carbon steel in also increased. (author)

105

Revascularization of an excisional wound in gingiva and oral mucosa. A scanning electron microscopic study using corrosion casts in rats.  

Science.gov (United States)

The purpose of this study was to examine microvascular regeneration associated with gingival wound healing. A full-thickness piece of gingiva and oral mucosa was excised along the palatal aspect of the right maxillary first and second molars in 20 young Wistar rats. The contralateral side served as unoperated control. After 2, 4, 7, 10 or 20 days of healing, microvascular corrosion casts were produced and examined by scanning electron microscopy. At 2 days, vessels surrounding the wound were dilated and impressions representing sites of leukocyte margination were prominent in the walls of venules. Capillary buds were emerging from venules and capillaries. At 4 days, the vessel buds had lengthened and connected in pairs to produce capillary loops. At 7 days, new vessels extended deeply into the wound space, mainly from the medical side, in a palisade-like pattern. At 10 days, the denuded bone surface was still not completely revascularized and Volkman's canals opening to the wound area were empty. At 20 days, the bone surface was covered by large, irregular vessels which originated mainly from the palatal mucosa. The periodontal ligament was less important in the tissue repair process, while the bony vasculature contributed little or not at all to revascularization of the healing gingiva and palatal mucosa. PMID:8714741

Selliseth, N J; Selvig, K A

1995-06-01

106

Influence of thermal aging on primary water stress corrosion cracking of cast duplex stainless steels  

International Nuclear Information System (INIS)

In order to evaluate the SCC susceptibility of cast duplex stainless steels which are often used for the main coolant piping of pressurized water reactors (PWRs), the slow strain rate test (SSRT) and the constant load test (CLT) of the materials were performed in simulated primary water at 360degC. The stainless steel contains ferritic phase with ranging from 8 to 23% and its mechanical properties are affected by long time thermal aging. Therefore, we paid attention to the influence of its ferrite content and thermal aging on the SCC susceptibility of this stainless steel and prepared three kinds of specimen with different ferrite contents (23%, 15% and 8%). The reduction in area observed by the SSRT in simulated primary water at 360degC was smaller than that obtained by the tensile test in air at the same temperature. Microcracks were observed on the unaged specimen surfaces and aged ones at 400degC for 10,000 hours after 3,000 hours of the CLT with the load condition of two times of yield strength. The SCC susceptibility was evaluated by reduction ratio defined by the ratio of the reduction in area by the SSRT to that by the tensile test. The reduction ratio was not clear for low ferrite specimens, but apparently decreased with increasing aging time for the specimen with 23% ferrite. This change by aging time can be explained as follows: (1) the brittle fracture in the unaged specimens is mainly caused by quasi-cleavage fracture in austenitic phase. (2) After aging,ture in austenitic phase. (2) After aging, it becomes a mixture of quasi-cleavage fracture in both austenitic and ferritic phases and phase boundary fracture of both phases. (author)

107

Dominância coronariana em corações humanos em moldes por corrosão / Coronary dominance patterns in the human heart investigated by corrosion casting  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Esse trabalho tem como objetivo analisar os padrões de dominância circulatória de corações humanos, o número de ramos que a artéria coronária direita fornece ao ventrículo esquerdo, o número de ramos que a artéria coronária esquerda fornece ao direito e a presença de anastomoses intercoron [...] arianas, com sua localização e frequência. MÉTODOS: Foram produzidos 25 moldes de corações submetidos à instilação de acrílico colorido e posterior corrosão com ácido clorídrico, no Laboratório de Cirurgia Experimental da FURB. Peças com lesões e cicatrizes não foram usadas. RESULTADOS: Os corações pertenciam a indivíduos de ambos os sexos, sendo 17 (68%) de indivíduos do sexo masculino, com idade média de 40,2 anos (15 a 70 anos). A dominância direita ocorreu em 18 (72%) peças, com 1, 2, 3 e 4 ramos em 2, 14, 2 e 1 moldes, respectivamente; a dominância esquerda foi observada em 5 (20%) casos, com 1 ramo em 4 moldes e 2 em 1 molde; e a dominância balanceada foi verificada em 2 (8%) moldes. Houve diferença significativa entre a dominância direita e esquerda (? > 5%), direita e balanceada (? > 5%) e sem significância entre esquerda e balanceada (? Abstract in english OBJECTIVES: The aim of this work was to analyze the dominance patterns of the circulation of the human heart, the number of branches from the right coronary artery to the left ventricle, the number of branches from the left coronary artery to the right ventricle and the frequency and location of int [...] ercoronary anastomoses. METHODS: Casts were made of 25 hearts by the injection of colored acrylic resin and subsequent corrosion using hydrochloric acid at the experimental surgery laboratory of Furb. Specimens with lesions or scars were discarded. RESULTS: The hearts, from both men (17 - 68%) and women (8 - 32%), had a mean age of 40.2 (15 to 70) years-old. Right dominance occurred in 18 (72%) subjects, with 1, 2, 3 and 4 branches leading to the left ventricle in 2, 14, 2 and 2 casts, respectively. Left dominance occurred in 5 (20%) with 1 branch leading to the right ventricle in 4 molds and 2 in one. Balanced circulation was observed in two molds (8%). There were significant differences between right and left dominance (? > 5%) and between right dominance and balanced circulation (? > 5%), however the same was not true between left dominance and balanced circulation (?

Décio Cavalet Soares, Abuchaim; Carlos Alexandre, Spera; Djalma Luis, Faraco; Jurandir Marcondes, Ribas Filho; Oswaldo, Malafaia.

2009-12-01

108

Effect of Heat Treatments on the Microstructure, Hardness and Corrosion Behavior of Nondendritic AlSi9Cu3(Fe Cast Alloy  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper we studied the influence of heat treatments on properties of AlSi9Cu3(Fe nondendritic cast alloy. Solution heat treatment, six hours at 520 °C, while making the grains more spherical modifies corrosion morphology into intergranular corrosion and corrosion surrounding spherical particles in 3 % NaCl solution. Past solution treatment, quenching at 520 °C after one hour with two weeks of natural aging transform the shape of grains into equiaxes form. Two weeks of natural aging and 30 minutes of aging at 150, 200, 250 °C after solution treatment and quenching give birth to the "Chinese script" form of the Al15(MnFe3Si intermetallic particles. The prolongation of the duration period of aging to one hour at 200 °C is sufficient to transform the morphology of corrosion into located corrosion by pitting, and a longer aging cancels the "Chinese script" form. DOI: http://dx.doi.org/10.5755/j01.ms.19.3.1397

Nacer ZAZI

2013-09-01

109

Corrosion  

International Nuclear Information System (INIS)

The corrosion behavior of materials in melts with different anions are considered. Topics presented include iron- and nickel-based alloys, flouride melts, nitrate and nitride melts, hydroxide melts, carbonate melts, and sulfate melts

110

A Comparative Analysis of the Corrosive Effect of Artificial Saliva of Variable pH on DMLS and Cast Co-Cr-Mo Dental Alloy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Dental alloys for direct metal laser sintering (DMLS) are available on the market today, but there is little scientific evidence reported on their characteristics. One of them is the release of ions, as an indicator of the corrosion characteristics of a dental alloy. Within this research, the difference in the elution of metals from DMLS and cast (CM) samples of Co-Cr-Mo dental alloy in saliva-like medium of three different pH was examined by inductively-coupled plasma mass spectrometry (ICP-...

Tatjana Puskar; Danimir Jevremovic; Williams, Robert J.; Dominic Eggbeer; Djordje Vukelic; Igor Budak

2014-01-01

111

A galvanic corrosion study of brass/stainless steel and brass/cast iron couples; Estudio de corrosion galvanica en pares laton/acero inoxidable y laton/fundicion de hierro  

Energy Technology Data Exchange (ETDEWEB)

Corrosion attack in heat exchanger systems is a topic of main interest for the maintenance in each industrial plant. These are multi galvanic systems with particular geometric and fluidodynamic complexity. Corrosive damages include zinc selective dealeation in copper alloys. In order to explain zinc dealeation attack, this paper deals with laboratory scale testing, characterization and interactions between two copper and zinc alloys (Yellow brass UNS C268 and Admiralty brass UNS C443) compared to AISI 316 stainless steel and cast iron. The tests were performed at 20 degree centigrade in 1.5 % NaCl and 1.5 % Na{sub 2}SO{sub 4} solutions, pH 8 and each material was characterized by potentiodynamic sweeps. The couples are analyzed by studying transient galvanic currents. We conclude about the cause of the analyzed pathology, brass protection potential ranges and its coupling compatibility with other metals. (Author) 33 refs.

Ohanian, M.; Diaz, V.; Corengia, M.; Zinola, C. F.

2011-07-01

112

Physics-Based Stress Corrosion Cracking Component Reliability Model cast in an R7-Compatible Cumulative Damage Framework  

International Nuclear Information System (INIS)

This is a working report drafted under the Risk-Informed Safety Margin Characterization pathway of the Light Water Reactor Sustainability Program, describing statistical models of passives component reliabilities. The Risk-Informed Safety Margin Characterization (RISMC) pathway is a set of activities defined under the U.S. Department of Energy Light Water Reactor Sustainability Program. The overarching objective of RISMC is to support plant life-extension decision-making by providing a state-of-knowledge characterization of safety margins in key systems, structures, and components (SSCs). The methodology emerging from the RISMC pathway is not a conventional probabilistic risk assessment (PRA)-based one; rather, it relies on a reactor systems simulation framework in which physical conditions of normal reactor operations, as well as accident environments, are explicitly modeled subject to uncertainty characterization. RELAP 7 (R7) is the platform being developed at Idaho National Laboratory to model these physical conditions. Adverse effects of aging systems could be particularly significant in those SSCs for which management options are limited; that is, components for which replacement, refurbishment, or other means of rejuvenation are least practical. These include various passive SSCs, such as piping components. Pacific Northwest National Laboratory is developing passive component reliability models intended to be compatible with the R7 framework. In the R7 paradigm with the R7 framework. In the R7 paradigm, component reliability must be characterized in the context of the physical environments that R7 predicts. So, while conventional reliability models are parametric, relying on the statistical analysis of service data, RISMC reliability models must be physics-based and driven by the physical boundary conditions that R7 provides, thus allowing full integration of passives into the R7 multi-physics environment. The model must also be cast in a form compatible with the cumulative damage framework that R7 is being designed to incorporate. Primary water stress corrosion cracking (SCC) of reactor coolant system Alloy 82/182 dissimilar metal welds has been selected as the initial application for examining the feasibility of R7-compatible physics-based cumulative damage models. This is a potentially risk-significant degradation mechanism in Class 1 piping because of its relevance to loss of coolant accidents. In this report a physics-based multi-state model is defined (Figure ES-1), which describes progressive degradations of dissimilar metal welds from micro-crack initiation to component rupture, while accounting for the possibility of interventions and repair. The cumulative damage representation of the multi-state model and its solutions are described, along with the conceptual means of integration into the R7 environment.

113

Architectural optimization of an epoxy-based hybrid sol-gel coating for the corrosion protection of a cast Elektron21 magnesium alloy  

Science.gov (United States)

An epoxy-based hybrid sol-gel coating was prepared in various architectural configurations has been studied for the corrosion protection of a cast Elektron21 magnesium alloy. The creation of a single layer of this coating presents defects consisting of macro-pores and protuberances, which opens access for corrosive species to reach the metallic substrate. These defects are suspected to result from the high reactivity of the substrate, as well as to the irregular topography of the substrate disrupted by the microstructure of the own magnesium alloy. Hence, a sol-gel coating in bilayer architecture is proposed, where the first layer would “inert” the surface of the magnesium substrate, and the second layer would cover the defects of the first layer and also thickening the coating. The morphological characteristics of the sol-gel coatings were analyzed by scanning electron microscopy (SEM), and their corrosion behavior was evaluated by OCP (open circuit potential) monitoring and electrochemical impedance spectroscopy (EIS) in chloride media. It is shown that both the architectural arrangement and the individual thickness of the first and second layers have an important influence on the anticorrosion performances of the protective system, just as much as its global thickness.

Murillo-Gutiérrez, N. V.; Ansart, F.; Bonino, J.-P.; Kunst, S. R.; Malfatti, C. F.

2014-08-01

114

Intergranular pitting and abrasive corrosion of duplex 25Cr-5Ni-6Mo stainless cast steels with nitrogen  

International Nuclear Information System (INIS)

The corrosion and corrosion-erosion resistance of duplex steels 22-25% Cr, 6% Ni, 3-5% Mo, 0.1-0.2% N have been investigated in aqueous chloride solutions. The investigated alloys showed very good resistance against pitting and intergranular corrosion in the passive range of temperature up to 50oC. Anodic polarisation measurements performed in aqueous 1M H2SO4 + 1M NaCl solutions show that the morphology and content of ferrite influence the dissolution rate of alloys in the active range - range of potentials were passivation of alloys does not occur. (author)

115

Effect of Sn addition on the corrosion behavior of Ti-7Cu-Sn cast alloys for biomedical applications.  

Science.gov (United States)

The aim of this study was to investigate the effects of Sn content on the microstructure and corrosion resistance of Ti7CuXSn (x=0-5wt.%) samples. The corrosion tests were carried out in 0.9wt.% NaCl solution at 25°C. The electrochemical corrosion behavior of the Ti7CuXSn alloy samples was evaluated using potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), and equivalent circuit analysis. The resulting impedance parameters and polarization curves showed that adding Sn improved the electrochemical corrosion behavior of the Ti7CuXSn alloy. The Ti7CuXSn alloy samples were composed of a dual-layer oxide consisting of an inner barrier layer and an outer porous layer. PMID:25491984

Tsao, L C

2015-01-01

116

Response of fine-cast gas turbine blade materials to mechanical long-term stress and hot gas corrosion  

International Nuclear Information System (INIS)

Using important uncoated and coated blade materials for industrial and aircraft gas turbines the fatigue behavior and the LCF tensile swelling behaviour were examined under flowing hot gas. Gas turbine specific corrosion cases were investigated in the range of relatively high temperatures. The time-dependent strength values of the base materials are usually specified in air, so the question was whether hot gas corrosion lowers these values more strongly than can be explained by the reduction of cross section as a result of hot gas corrosion. It was also investigated whether the (Al, PtAl, CoCrAlY, CoNiCrAlY) protective layers of this combined thermal and mechanical corrosive stress can resist without premature failure. Flight turbine materials showed strong corrosion damage at 1000 degrees Centigrade under corrosion condition intensified by sea salt. Large-scale cross-section losses were found in the M 002 mod uncoated monocrystal alloy already before 1000 hours of exposure, although the fatigue strength was reduced not more than the explainable measure. Layers on the basis of Al, PtAl and CoNiCrAlY were consumed to a large extent after approximately 2000 hours. (orig./RHM)

117

Study of waterline corrosion on the carbon steel liner cast in concrete at the condensation pool. I. Literature review II. Study of the risk for waterline corrosion on the steel liner cast in concrete at the cylinder wall at Barsebaeck 1  

International Nuclear Information System (INIS)

The reactor containment in Swedish BWR-type nuclear power plants consists of an inner cylinder-shaped container of stainless steel, with an outer liner of carbon steel about 300 mm from the stainless steel container, both cast in concrete. If water leaks from the inner stainless steel container into the concrete, the risk of corrosion on the carbon steel liner may be increased by the presence of a waterline, and voids in the concrete at the metal surface. The first part of the report is a survey of published information regarding waterline corrosion and the effect of wholly or partly liquid-filled voids at a steel surface cast in concrete. The second part is a report on the investigations of the corrosion status of the steel liner on the inside of the reactor containment at the Barsebaeckverket 1 plant and of the laboratory investigations of the concrete samples that were taken from the reactor containment wall. The waterline corrosion effect is caused by local differences in environmental factors at the water/air border, primarily the supply of oxygen (air), which allows corrosion cells similar to galvanic cells to be set up. On a vertical, partly immersed steel structure the corrosion rate largely varies with the supply of oxygen, with the highest corrosion rate at or immediately above the waterline, where the supply of both oxygen (air) and electrolyte is good. The relative corrosion rates around the waterline may be modified by the action of various concentration ed by the action of various concentration cells. Waterline effects due to aeration cells or other concentration cells have been shown to increase the risk for corrosion damage locally, even when the overall corrosion rate does not increase, since corrosion is concentrated to a smaller area and may have a more localised character. Waterline conditions can also develop at a cast-in metal surface inside partly water-filled voids in the concrete. Voids as such at a concrete/metal interface, leaving metal without adhering concrete, have also been shown to increase the corrosion risk. In laboratory experiments, corrosion on bare (not concrete-covered) metal surfaces occurred at quite low chloride concentration and high pH value in the surrounding concrete. Based on the results of the investigations of the corrosion status of the steel liner, and of the concrete samples from the reactor containment the following conclusions can be stated: Visual inspections of the corrosion state of the steel liner showed that there was only superficial corrosion on the liner. The liner had not been subject to waterline corrosion. The appearance of the corrosion products on the steel liner varied with the supply of oxygen. Red, grey and black-coloured corrosion products were present, presumably iron oxide-hydroxide (FeOOH), hematite (Fe2O3), and magnetite (Fe3O4). The superficial corrosion that was observed on the steel liner is probably due to the fact that the reactor containment has been drained of water since 2000, which locally changed the environment in the interface between concrete and steel: drying-up, with better access of air (oxygen). The overall state of the concrete in the examined core samples is good. The crack frequency in the concrete is low, except in the outmost (0-2 mm) concrete layer. The top layer with a high frequency of microcracks in the concrete samples has a maximum depth of 2 mm in all samples except 1:5 (high frequency of cracks to a depth of 11 mm) and 3:3 (high frequency of cracks to a depth of 14 mm). The pH value of the water in contact with the concrete binder is 12,5. The outer layer of the concrete (0-2 mm depth in concrete) is carbonated and shows signs of water damage. Secondary ettringite had formed in the voids of the concrete as a result of the exposure to humidity. This has no significant influence on the properties of the concrete

118

Corrosion fatigue of AZ91E-T6 cast magnesium alloy in a 3.5 percent NaCl aqueous environment  

Energy Technology Data Exchange (ETDEWEB)

The objective of this research was to obtain and compare constant and variable amplitude fatigue behavior of AZ91E-T6 cast magnesium alloy in both an air and 3.5% NaCl aqueous corrosive environment. An additional objective was to determine if commonly used models that describe fatigue behavior and fatigue life are applicable to this material and test environment. Fatigue tests included constant amplitude strain-controlled low cycle fatigue with strain ratio, R, equal to 0, {minus}1 and {minus}2, Region 2 constant amplitude fatigue crack growth with load ratio, R, equal to 0.05 and 0.5 and variable amplitude fatigue tests using keyhole notched specimens. In all fatigue tests, the corrosion environment was significantly detrimental relative to the air environment. Mean strains influenced fatigue life only if accompanied by significant mean stress. The Morrow and Smith, Watson, and Topper mean stress models provided both accurate and inaccurate fatigue life calculations. Likewise, variable amplitude fatigue life calculations using the local strain approach and based upon the formation of a 1 mm crack at the keyhole notch were both accurate and fairly inaccurate depending on the specific model used.

Stephens, R.I.; Schrader, C.D.; Lease, K.B. [Univ. of Iowa, Iowa City, IA (United States). Mechanical Engineering Dept.

1995-07-01

119

Erosion-corrosion and surface protection of A356 Al/ZrO2 composites produced by vortex and squeeze casting  

International Nuclear Information System (INIS)

Erosive-corrosive wear behavior of Al-Si-Mg (A356 Al) alloy and its composite reinforced by ZrO2 and produced by vortex and squeeze techniques has been studied in water containing 40% sand slurry. The worn surfaces of investigated alloys have been studied and the mechanism of material removal from the specimen surface was examined to be associated with number of subsequent and repetitive stages. The possibility of Ni coating for Al composites by electrochemical deposition is investigated. The surface layer was characterized by microhardness measurements, optical microscope, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) analysis. The electrochemical results obtained from polarization studies for Ni-coated, A356 Al alloy and composites in 3.5% sodium chloride solution indicated higher protection exhibited by Ni coatings due to the nickel properties. The squeezed cast composite is characterized by high corrosion and wear resistance comparing the composite produced by vortex process. This study revealed that the Ni-coated materials provide higher abrasive resistance and therefore a longer service life compared to A356 Al-ZrO2

120

Effect of sulfate on the transformation of corrosion scale composition and bacterial community in cast iron water distribution pipes  

Science.gov (United States)

The stability of iron corrosion products and the bacterial composition of biofilm in drinking water distribution systems (DWDS) could have great impact on the water safety at the consumer ends. In this work, pipe loops were setup to investigate the transformation characteristics ...

 
 
 
 
121

Casting Atmosphere Effects on the Precipitates, Magnetism, and Corrosion Resistance of Fe78Si9B13 Glassy Alloys  

Science.gov (United States)

The precipitates, magnetism, and corrosion resistance of Fe78Si9B13 glassy samples fabricated in vacuum and air atmospheres (labeled as VAC and AIR samples, respectively) were studied. The findings show that the fraction of the amorphous phase in VAC samples is lower than that in the AIR counterparts. The Fe phase in VAC samples grows preferentially along the orientation. The distribution of magnetization M 4000 of VAC samples oriented parallel and orthogonal to the field ( H // and H ?) at H = 4000 Oe is more scattered than AIR samples. The corrosion resistance of VAC samples is lower than AIR counterparts, which can be attributed to the minor alloying effect of oxygen and the passive effect of silicon atoms supplied from the amorphous phase.

Meng, L. L.; Li, X. Y.; Pang, J.; Wang, L.; An, B.; Yin, L. J.; Song, K. K.; Wang, W. M.

2013-11-01

122

Influence of thermal aging on primary water stress corrosion cracking of cast duplex stainless steel (second report). Consideration on fractography after slow strain rate technique  

International Nuclear Information System (INIS)

In order to evaluate the stress corrosion cracking (SCC) susceptibility of cast duplex stainless steel which is used for the main coolant pipe of pressurized water reactors (PWRs), the slow strain rate technique (SSRT) and the constant load test (CLT) of the materials were performed in simulated primary water at 360degC. The cast duplex stainless steel contains ferrite phase with ranging from 8 to 23% and its mechanical properties are affected by long time thermal aging. Therefore, we paid attention to the influence of its ferrite content and thermal aging on the SCC susceptibility of this unaged and aged stainless steel and prepared three kinds of specimen with different ferrite contents (23%, 15% and 8%). The brittle fracture of the unaged specimens after SSRT mainly consists of quasi-cleavage fracture in austenitic phase. After aging, it changes to a mixture of quasi-cleavage fracture in both austenitic and ferritic phases. Microcracks were observed on the unaged specimen surfaces and aged ones for 10,000 hours at 400degC after about 10,000 hours of the CLT under the load condition of 1.2?2.0 times of yield strength. The crack initiation sites of CLT specimens are similar to SSRT fracture surfaces. The SCC susceptibility of this 23% ferrite material increases with aging time at 400degC. The SCC susceptibility of 15% and 23% ferrite materials are higher than that of 8% ferrite material with aging condition for 30,000h at 400degC. (author)degC. (author)

123

A Comparative Analysis of the Corrosive Effect of Artificial Saliva of Variable pH on DMLS and Cast Co-Cr-Mo Dental Alloy  

Directory of Open Access Journals (Sweden)

Full Text Available Dental alloys for direct metal laser sintering (DMLS are available on the market today, but there is little scientific evidence reported on their characteristics. One of them is the release of ions, as an indicator of the corrosion characteristics of a dental alloy. Within this research, the difference in the elution of metals from DMLS and cast (CM samples of Co-Cr-Mo dental alloy in saliva-like medium of three different pH was examined by inductively-coupled plasma mass spectrometry (ICP-MS. The obtained results show that the metal elution in artificial saliva from the DMLS alloy was lower than the elution from the CM alloy. The release of all investigated metal ions was influenced by the acidity, both from the DMLS and CM alloy, throughout the investigated period of 30 days. The change in acidity from a pH of 6.8 to a pH of 2.3 for the cast alloy led to a higher increase of the elution of Co, Cr and Mo from CM than from the DMLS alloy. The greatest release out of Co, Cr and Mo was for Co for both tested alloys. Further, the greatest release of all ions was measured at pH 2.3. In saliva of pH 2.3 and pH 4.5, the longer the investigated period, the higher the difference between the total metal ion release from the CM and DMLS alloys. Both alloys showed a safe level of elution according to the ISO definition in all investigated acidic environments.

Tatjana Puskar

2014-09-01

124

Heat and corrosion resistant cast CN-12 type stainless steel with improved high temperature strength and ductility  

Science.gov (United States)

A cast stainless steel alloy and articles formed therefrom containing about 0.5 wt. % to about 10 wt. % manganese, 0.02 wt. % to 0.50 wt. % N, and less than 0.15 wt. % sulfur provides high temperature strength both in the matrix and at the grain boundaries without reducing ductility due to cracking along boundaries with continuous or nearly-continuous carbides. Alloys of the present invention also have increased nitrogen solubility thereby enhancing strength at all temperatures because nitride precipitates or nitrogen porosity during casting are not observed. The solubility of nitrogen is dramatically enhanced by the presence of manganese, which also retains or improves the solubility of carbon thereby providing additional solid solution strengthening due to the presence of manganese and nitrogen, and combined carbon. Such solution strengthening enhances the high temperature precipitation-strengthening benefits of fine dispersions of NbC. Such solid solution effects also enhance the stability of the austenite matrix from resistance to excess sigma phase or chrome carbide formation at higher service temperatures. The presence of sulfides is substantially eliminated.

Mazias, Philip J. (Oak Ridge, TN); McGreevy, Tim (Morton, IL); Pollard,Michael James (East Peoria, IL); Siebenaler, Chad W. (Peoria, IL); Swindeman, Robert W. (Oak Ridge, TN)

2007-08-14

125

Heat and corrosion resistant cast CF8C stainless steel with improved high temperature strength and ductility  

Science.gov (United States)

A CF8C type stainless steel alloy and articles formed therefrom containing about 18.0 weight percent to about 22.0 weight percent chromium and 11.0 weight percent to about 14.0 weight percent nickel; from about 0.05 weight percent to about 0.15 weight percent carbon; from about 2.0 weight percent to about 10.0 weight percent manganese; and from about 0.3 weight percent to about 1.5 weight percent niobium. The present alloys further include less than 0.15 weight percent sulfur which provides high temperature strength both in the matrix and at the grain boundaries without reducing ductility due to cracking along boundaries with continuous or nearly-continuous carbides. The disclosed alloys also have increased nitrogen solubility thereby enhancing strength at all temperatures because nitride precipitates or nitrogen porosity during casting are not observed. The solubility of nitrogen is dramatically enhanced by the presence of manganese, which also retains or improves the solubility of carbon thereby providing additional solid solution strengthening due to the presence of manganese and nitrogen, and combined carbon.

Maziasz, Philip J. (Oak Ridge, TN); McGreevy, Tim (Washington, IL); Pollard, Michael James (Peoria, IL); Siebenaler, Chad W. (Dunlap, IL); Swindeman, Robert W. (Oak Ridge, TN)

2010-08-17

126

Zirconium and cast zirconium  

International Nuclear Information System (INIS)

A survey is given on the occurence of zirconium, production of Zr sponge and semi-finished products, on physical and mechanical properties, production of Zr cast, composition of the commercial grades and reactor grades qualities, metal cutting, welding, corrosion behavior and use. (IHOE)

127

A study on the corrosion behavior of Ce-modified cast AZ91 magnesium alloy in the presence of sulfate-reducing bacteria  

International Nuclear Information System (INIS)

The corrosion behavior of AZ91Ce alloy in the presence of sulfate-reducing bacteria (SRB) was investigated using a specially designed in-situ corrosion method. For comparison, AZ91 alloy was also studied under the same corrosion condition. It seemed that AZ91Ce alloy was susceptible to crystal boundary corrosion under SRB condition to some extent. A possible mechanism for the crystal boundary corrosion was proposed. The microstructure and corrosion morphologies of alloys were analyzed by optical microscope and SEM, and the corrosion products were detected by X-ray photoelectron spectrometer (XPS). The analysis results showed that Ce in AZ91 alloy can reduce the grain size, and impede the formation of oxide, and thereby improved the corrosion performance. The electrochemical test revealed that the formation of Ce compound can restrict the cathodic reaction, and thus improve the corrosion resistance significantly as observed under the sterile condition. However, it appeared that the improvement was unconspicuous in the presence of SRB

128

A study on the corrosion behavior of Ce-modified cast AZ91 magnesium alloy in the presence of sulfate-reducing bacteria  

Energy Technology Data Exchange (ETDEWEB)

The corrosion behavior of AZ91Ce alloy in the presence of sulfate-reducing bacteria (SRB) was investigated using a specially designed in-situ corrosion method. For comparison, AZ91 alloy was also studied under the same corrosion condition. It seemed that AZ91Ce alloy was susceptible to crystal boundary corrosion under SRB condition to some extent. A possible mechanism for the crystal boundary corrosion was proposed. The microstructure and corrosion morphologies of alloys were analyzed by optical microscope and SEM, and the corrosion products were detected by X-ray photoelectron spectrometer (XPS). The analysis results showed that Ce in AZ91 alloy can reduce the grain size, and impede the formation of oxide, and thereby improved the corrosion performance. The electrochemical test revealed that the formation of Ce compound can restrict the cathodic reaction, and thus improve the corrosion resistance significantly as observed under the sterile condition. However, it appeared that the improvement was unconspicuous in the presence of SRB.

Liu Yaohui [Department of Materials Science and Engineering, Jilin University at Nanling Campus, Renmin Street 5988, Changchun 130025 (China)], E-mail: liuyaohui2005@yahoo.com; Wang Qiang; Song Yulai; Zhang Dawei; Yu Sirong; Zhu Xianyong [Department of Materials Science and Engineering, Jilin University at Nanling Campus, Renmin Street 5988, Changchun 130025 (China)

2009-04-03

129

Lean duplex stainless steels—The role of molybdenum in pitting corrosion of concrete reinforcement studied with industrial and laboratory castings  

International Nuclear Information System (INIS)

Highlights: ? Mo influence on corrosion of DSS was studied with industrial and laboratory heats. ? Beneficial effect of Mo was associated with ferrite corrosion resistance. ? Mo-species in the alkaline solution did not improve pit resistance. ? Mo role in DSS under alkaline conditions was ascribed to its presence in oxide film. - Abstract: The influence of Mo addition on pitting corrosion resistance of lean duplex stainless steels is not clearly understood in alkaline chloride conditions even if this element is widely recognized to increase corrosion resistance in acidic and neutral environments. This work aims to study the effect of Mo on pitting corrosion of lean duplex stainless steels in synthetic concrete pore solutions simulating degraded concrete. Results are discussed with respect to the influence of Mo on pitting potential for two industrial alloys in chloride rich and carbonated solution simulating concrete pore environments. To establish the real effect of Mo addition on lean duplex corrosion and passivation properties, two specific laboratory lean duplex alloys, for which the only difference is strictly the Mo content, are also studied. Mo presented a strong positive influence on the pitting corrosion resistance of industrial and laboratory lean duplex stainless steels in all studied chloride-rich solutions, but its effect is as less pronounced as the pH increases. In presence of Mo, pitting initiates and propagates preferentially in the austenitics preferentially in the austenitic phase at high temperature.

130

Estudio de los efectos corrosivos del diésel y biodiésel sobre una fundición de hierro gris / Study of the corrosive effects of diesel and biodiesel on gray cast iron  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish La fundición de hierro gris es un material utilizado en la industria de los combustibles por su bajo costo, alta resistencia mecánica y su proceso de manufactura. Presenta resistencia química deficiente por su alta reactividad y propensión a la corrosión. El uso del biodiésel crea retos de com [...] patibilidad para este material, debido a su auto-oxidación y alta higroscopicidad, que actúan como aceleradores de los procesos corrosivos. Dentro de las aplicaciones dadas a este material, existen condiciones de alta temperatura y presión que afectan la interacción con el biodiésel y su proceso de corrosión. Las muestras de fundición de hierro gris fueron sometidas al contacto con biodiésel de palma mediante la técnica de inmersión estática, en condiciones ambientales (18°C) y de ciclos térmicos (Oxidación cíclica entre 18 y 200°C) con la finalidad de cuantificar los efectos corrosivos. El material fue inmerso por un período de 450 horas y se registró su peso periódicamente. Se analizó adicionalmente la superficie del material por microscopía óptica, microscopía electrónica de barrido (SEM) y difracción de rayos X (XRD). Los resultados indicaron mayor velocidad de corrosión sobre la fundición de hierro inmersa en el combustible biodiésel, en comparación al diésel regular. Adicionalmente se observó que los ciclos térmicos aceleran los procesos corrosivos hasta 4 veces con respecto a la temperatura ambiente. Abstract in english Gray cast iron is a material used in the fuel industry by its low cost, high mechanical strength and its manufacturing process. It has poor chemical resistance due to its high reactivity and susceptibility to corrosion. The use of biodiesel creates challenges of compatibility for this material, due [...] to its oxidation and high hygroscopicity, which act as accelerators of corrosive processes. Within the applications this material has to offer, there are conditions of high temperature and pressure that affect the interaction with biodiesel and its process of corrosion. Gray cast iron samples were subjected to contact with palm biodiesel using the technique of static immersion in ambient conditions (18°C) and thermal cycles (Cyclic oxidation since18 to 200°C) and the corrosive effects were quantified. The material was immersed for a period of 450 hours and its weight was periodically recorded until the end of the test. The surface of the material was also analyzed by optical microscopy, scanning electron microscopy and x-ray diffraction. The results indicated a greater rate of corrosion on the cast iron for biodiesel fuel compared to regular diesel. In addition, it was observed that the thermal cycles accelerate the corrosive processes up to 4 times with respect to the ambient temperature.

Ariel Augusto, Amaya; Oscar Edwin, Piamba; Jhon Jairo, Olaya.

2014-06-01

131

Bimetallic layered castings alloy steel – grey cast iron  

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Full Text Available Purpose: In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast process so-called method of mould cavity preparation.Design/methodology/approach: Prepared bimetallic layered castings consist two fundamental parts i.e. bearing part and working part (layer. The bearing part of bimetallic layered casting is typical foundry material i.e. pearlitic grey cast iron, whereas working part (layer is depending on accepted variant plates of alloy steels sort X6Cr13, X12Cr13, X10CrNi18-8 and X2CrNiMoN22-5-3. The ratio of thickness between bearing and working part is 8:1. The verification of the bimetallic layered castings was evaluated on the basis of ultrasonic NDT (non-destructive testing, structure and macro- and microhardness researches. Moreover was made computer simulation of solidification of bimetallic layered casting in NovaFlow&Solid software.Findings: The results of studies and their analysis show efficiency of new, innovative technology of corrosion and heat resisting layered castings.Research limitations: In further research, authors of this paper are going to application of different material on bearing part of bimetallic layered casting.Practical implications: Prepared bimetallic layered castings according to work out technology can work in conditions, which require from working surface layer of element a high heat resistance and/or corrosion resistance in medium for example of industrial water.Originality/value: The value of this paper resides in new effective method of manufacture of heat resisting castings, mainly for lining of quenching car to coke production

T. Wróbel

2011-04-01

132

Structure of a cast high-strength corrosion-resistant 05Kh20AG10N3MF austenitic steel containing 0.40 or 0.53% nitrogen  

Science.gov (United States)

The phase composition and fine structure of a high-strength corrosion-resistant 05Kh20AG10N3MF austenitic steel containing 0.40 or 0.53% N are studied by X-ray diffraction and electron microscopy. In the as-cast state, this steel has a structure containing austenite, ? ferrite, and dispersed CrV(C, N) carbonitrides. The ? ferrite is represented by layers between austenite grains, the dislocation density in which is lower than in the ? ferrite. After quenching from 1100, 1150, and 1200°C, the structure of the steel with 0.53% N has no ? ferrite and the structure of the steel with 0.40% N has a low ?-ferrite content and ?-phase precipitates.

Blinov, V. M.; Bannykh, I. O.; Betsofen, S. Ya.; Khodyrev, M. S.; Blinov, E. V.

2010-01-01

133

Influência da taxa de resfriamento na corrosão em aço inoxidável fundido / Influence of cooling rate on corrosion of casting stainless steel  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese As indústrias de extração de petróleo e produção de gás têm utilizado de forma crescente os aços inoxidáveis, por serem ligas que combinam boa propriedade mecânica a resistência à corrosão e são economicamente viáveis, para aplicações em linha de escoamento onshore e offshore. Estes materiais geralm [...] ente exibem excelente resistência à corrosão, tenacidade e soldabilidade. Entretanto, de todos os tipos de corrosão, a corrosão de localizada por pite é o processo mais difícil de controlar. O presente trabalho estuda o efeito da taxa de resfriamento na corrosão dos aços inoxidáveis martensíticos 13Cr-4Ni-0,02C e 13Cr-2Ni-0,1C. Foi observado que o aumento da taxa de resfriamento levou a formação de uma microestrutura refinada e com estruturas dendríticas. A taxa de corrosão foi determinada por ensaio de imersão e foi observado que quanto maior a taxa de resfriamento, maior a taxa de corrosão para os aços estudados. A densidade de pite, profundidade de pite e taxa de corrosão foram maiores para o aço 13Cr-2Ni-0,1C. Isto se deve por apresentar uma microestrutura mais refinada e maior quantidade de estruturas dendríticas, que podem atuar como sítios nucleantes no processo de corrosão. Abstract in english The oil drilling and gas production industries has been making increasing use of stainless steels because of their good combination of mechanical propriety and corrosion resistance and economically-viables alloys for onshore and offshore pipeline applications. These materials usually exhibit excelle [...] nt corrosion resistance, toughness and weldability. However, of all the different types of corrosion, localized pitting corrosion is the most difficult process to control. The present work studies the effect of the cooling rate on corrosion of martensitics stainless steels 13Cr-4Ni-0,02C and 13Cr-2Ni-0,1C. It was observed that higher cooling rate led to the formation of a finer microstructure and with dendritics structures presence. The corrosion rate was determined by immersion tests and it was observed that the higher cooling rate, the higher the corrosion rate for the studied steels. Pitting density, pitting depth, and corrosion rates were all higher for 13Cr-2Ni-0,1C steel. This is due to its more refined microstructure and more dendritics structures that can act as nucleation sites for the corrosion process.

N.A., Mariano; J.P., Murolo; V.F., Pereira; A.S.N., Pallone; M.A.G., Tommaselli.

2008-06-01

134

Improvement of corrosion resistance in NaOH solution and glass forming ability of as-cast Mg-based bulk metallic glasses by microalloying  

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Full Text Available The influences of the addition of Ag on the glass forming ability (GFA and corrosion behavior were investigated in the Mg-Ni-based alloy system by X-ray diffraction (XRD and electrochemical polarization in 0.1 mol/L NaOH solution. Results shows that the GFA of the Mg-Ni-based BMGs can be improved dramatically by the addition of an appropriate amount of Ag; and the addition element Ag can improve the corrosion resistance of Mg-Ni-based bulk metallic glass. The large difference in atomic size and large negative mixing enthalpy in alloy system can contribute to the high GFA. The addition element Ag improves the forming speed and the stability of the passive film, which is helpful to decrease the passivation current density and to improve the corrosion resistance of Mg-Ni-based bulk metallic glass.

Peng Hao

2011-02-01

135

The effects of trace impurities in coal-derived liquid fuels on deposition and accelerated high temperature corrosion of cast superalloys  

Science.gov (United States)

The effects of trace metal impurities in coal-derived liquids on deposition, high temperature corrosion and fouling were examined. Alloys were burner rig tested from 800 to 1100 C and corrosion was evaluated as a function of potential impurities. Actual and doped fuel test were used to define an empirical life prediction equation. An evaluation of inhibitors to reduce or eliminate accelerated corrosion was made. Barium and strontium were found to limit attack. Intermittent application of the inhibitors or silicon additions were found to be effective techniques for controlling deposition without losing the inhibitor benefits. A computer program was used to predict the dew points and compositions of deposits. These predictions were confirmed in deposition test. The potential for such deposits to plug cooling holes of turbine airfoils was evaluated. Tests indicated that, while a potential problem exists, it strongly depended on minor impurity variations.

Lowell, C. E.; Deadmore, D. J.; Santoro, G. J.; Kohl, F. J.

1981-01-01

136

Corrosion Resistance of Laser Produced in-situ Particle Reinforced Fe-matrix Composite Coating with High Nickel Content on Spheroidal Graphite Cast Iron  

Science.gov (United States)

Fe-matrix composite coatings reinforced by in-situ particles with high nickel content were produced on QT450-10 by laser alloying. Coatings with different microstructure proportions and particle distributions were obtained by the adjustment of the content of Ni, Ti and Zr in the alloying powder and the laser parameters. The influence of the content of Ni and the particle distribution on coating's corrosion resistance is studied, which is revealed by the electrochemical characteristics. The results indicate that the alloying coating with more content of nickel and less particles get corroded much harder with a higher corrosion rate.

Qiwen, W.; Mingxing, M.; Cunyuan, P.; Xiaohui, Y.; Weiming, Z.

137

Effects of alloy composition on cyclic flame hot-corrosion attack of cast nickel-base superalloys at 900 deg C  

Science.gov (United States)

The effects of Cr, Al, Ti, Mo, Ta, Nb, and W content on the hot corrosion of nickel base alloys were investigated. The alloys were tested in a Mach 0.3 flame with 0.5 ppmw sodium at a temperature of 900 C. One nondestructive and three destructive tests were conducted. The best corrosion resistance was achieved when the Cr content was 12 wt %. However, some lower-Cr-content alloys ( 10 wt%) exhibited reasonable resistance provided that the Al content alloys ( 10 wt %) exhibited reasonable resistance provided that the Al content was 2.5 wt % and the Ti content was Aa wt %. The effect of W, Ta, Mo, and Nb contents on the hot-corrosion resistance varied depending on the Al and Ti contents. Several commercial alloy compositions were also tested and the corrosion attack was measured. Predicted attack was calculated for these alloys from derived regression equations and was in reasonable agreement with that experimentally measured. The regression equations were derived from measurements made on alloys in a one-quarter replicate of a 2(7) statistical design alloy composition experiment. These regression equations represent a simple linear model and are only a very preliminary analysis of the data needed to provide insights into the experimental method.

Deadmore, D. L.

1984-01-01

138

Effects of alloy composition on cyclic flame hot-corrosion attack of cast nickel-base superalloys at 900 deg C  

International Nuclear Information System (INIS)

The effects of Cr, Al, Ti, Mo, Ta, Nb, and W content on the hot corrosion of nickel base alloys were investigated. The alloys were tested in a Mach 0.3 flame with 0.5 ppmw sodium at a temperature of 900 C. One nondestructive and three destructive tests were conducted. The best corrosion resistance was achieved when the Cr content was 12 wt %. However, some lower-Cr-content alloys ( 10 wt%) exhibited reasonable resistance provided that the Al content alloys ( 10 wt %) exhibited reasonable resistance provided that the Al content was 2.5 wt % and the Ti content was Aa wt %. The effect of W, Ta, Mo, and Nb contents on the hot-corrosion resistance varied depending on the Al and Ti contents. Several commercial alloy compositions were also tested and the corrosion attack was measured. Predicted attack was calculated for these alloys from derived regression equations and was in reasonable agreement with that experimentally measured. The regression equations were derived from measurements made on alloys in a one-quarter replicate of a 2(7) statistical design alloy composition experiment. These regression equations represent a simple linear model and are only a very preliminary analysis of the data needed to provide insights into the experimental method

139

Effect of alloy composition on the sodium-sulfate induced hot corrosion attack of cast nickel-base superalloys at 900 C  

Science.gov (United States)

The effects of Cr, Al, Ti, Mo, Ta, Nb, and W content on the hot corrosion of Ni-base alloys were examined experimentally. The superalloys were tested for 300 1-hr cycles at 900 C in a Mach 0.3 burner rig flame containing 0.5 ppmw sodium. The data reveal that the best corrosion resistance is obtained when the Cr content is greater than 12 percent; however, good resistance is detected in some alloys with Cr content less than 10 percent provided that the Al content is less than 2.5 wt pct and the Ti content is less than 4 wt pct. It is observed that the influence of W, Ta, Mo, and Nb content on resistance is dependent on Al and Ti contents. The derivation of an equation for estimating hot corrosion attack as a function of alloy composition using multiple linear regression analysis is described. The applicability of the equation is tested using various data sets of alloys. It is noted that the equation can be used to explain the effects of alloy composition on attack rates.

Stearns, C. A.; Deadmore, D. L.; Barrett, C. A.

1987-01-01

140

The Mechanical and Corrosion Behaviors of As-cast and Re-melted AlCrCuFeMnNi Multi-Component High-Entropy Alloy  

Science.gov (United States)

A multi-component AlCrCuFeMnNi high-entropy alloy, prepared by vacuum induction melting, was investigated for structural, mechanical, and corrosion characteristics, before and after the re-melting process. Optical microscopy analysis revealed a dendritic solidification behavior. The interdendritic area contains two main phases and occasionally small hard phases. The re-melting process produced a finer dendritic structure, with rounded dendrites and reduced interdendritic hard phases. The SEM-EDAX analysis showed that the dendrite region contains a Widmanstatten type of structure and are composed of Cr-Fe rich phases, whereas the interdendrite region contains Cu and Mn rich phases. XRD analysis revealed two disordered BCC type A2 structures with high Cr and Fe content and an FCC A12 type of structure for the Cu and Mn rich interdendritic phase. The lattice constants, determined by X-ray diffraction, are 2.87 and 2.91 Å for the A2 phases and 3.67 Å for A1 phase. The Vickers micro hardness increased with the homogeneity of the alloy, having a maximum value of 4370 MPa for the re-melted sample. Corrosion tests carried out in 3.5 wt pct sodium chloride aerated solution indicated that the corrosion resistance improved with the re-melting process, being 1.5 to 2 times better than that of 304 stainless steel.

Soare, Vasile; Mitrica, Dumitru; Constantin, Ionut; Popescu, Gabriela; Csaki, Ioana; Tarcolea, Mihai; Carcea, Ioan

2014-08-01

 
 
 
 
141

Influence of reinforcement grade and matrix composition on corrosion resistance of cast aluminium matrix composites (A3xx.x/SiCp) in a humid environment  

Energy Technology Data Exchange (ETDEWEB)

A study of the influence of the silicon carbide (SiC{sub p}) proportion and the matrix concentration of four aluminium metal matrix composites (A360/SiC/10p, A360/SiC/20p, A380/SiC/10p, A380/SiC/20p) exposed to high relative humid environment was carried out under simulation in a climatic chamber. The matrix of A360/SiC/xxp composites was virtually free of copper while the A380/SiC/xxp matrix contained 3.13-3.45wt% Cu and 1.39-1.44wt% Ni. The kinetics of the corrosion process was studied on the basis of gravimetric tests. The nature of corrosion products was analysed by Scanning Electron Microscopy (SEM) and Low Angle X-Ray Diffraction (XRD) before and after accelerated testing to determine the influence of microstructural changes on corrosion behaviour during exposure to the corrosive environment. The corrosion damage to Al/SiCp composites was low at 80% Relative Humidity (RH) and increased with temperature, SiCp proportion, relative humidity and Cu matrix concentration. The main attack nucleation sites were the interface region between the matrix and the reinforcement particles. The corrosion process was influenced more by the concentration of alloy elements in the matrix than by the proportion of SiCp reinforcement. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Eine Studie zum Einfluss des Siliziumkarbidanteils (SiCp) und der Zusammensetzung des Grundwerkstoffs von vier Aluminiummatrixverbundwerkstoffen (A360/SiC/10p, A360/SiC/20p, A380/SiC/10p, A380/SiC/20p), die in Umgebungen mit relativ hoher Feuchtigkeit ausgelagert waren, wurde unter simulierten Bedingungen in einer Klimakammer durchgefuehrt. Die Matrix des A360/SiC/xxp-Verbundwerkstoffs war praktisch Kupfer-frei waehrend die A380/SiC/xxp Matrix 3,13-3,45 Gew.-% Cu und 1,39-1,44 Gew.-% Ni enthielt. Die Kinetik des Korrosionsprozesses wurde auf der Basis von gravimetrischen Messungen studiert. Die Beschaffenheit der Korrosionsprodukte wurde mittelt REM-Untersuchungen und Kleinwinkelroentgendiffraktometrie (XRD) vor und nach der beschleunigten Pruefung analysiert, um den Einfluss der Gefuegeveraenderungen auf das Korrosionsverhalten waehrend der Auslagerung in der korrosiven Umgebung zu bestimmen. Der Korrosionsschaden an den Al/SiCp-Verbundwerkstoffen war niedrig bei 80% relativer Feuchte und nahm mit der Temperatur, dem SiCp-Anteil, der relativen Feuchte und der Kupferkonzentration der Matrix zu. Die Hauptkeimbildungsbereiche fuer den Angriff befanden sich an der Grenzflaeche zwischen der Matrix und den Verstaerkungspartikeln. Der Korrosionsprozess wurde mehr durch die Konzentration der Legierungselemente in der Matrix als durch den Anteil der SiCp-Verstaerkung beeinflusst. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Pardo, A.; Viejo, F.; Carboneras, M. [Departamento de Ciencia de Materiales, Facultad de Quimica Universidad Complutense, 28040, Madrid (Spain); Merino, M.C. [Departamento de Ciencia de Materiales, Facultad de Quimica Universidad Complutense, 28040, Madrid (Spain); Departamento de Tecnologia Industrial, Universidad Alfonso X El Sabio, 28691, Villanueva de la Canada, Madrid (Spain); Lopez, M.D. [Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, 28931, Mostoles, Madrid (Spain); Merino, S. [Departamento de Tecnologia Industrial, Universidad Alfonso X El Sabio, 28691, Villanueva de la Canada, Madrid (Spain)

2003-05-01

142

40 CFR Appendix - Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC...  

Science.gov (United States)

...HAP Emissions Limits for Open Molding, Centrifugal Casting, and...Air Pollutants: Reinforced Plastic Composites Production Other...HAP Emissions Limits for Open Molding, Centrifugal Casting, and...limit is a 1 . . . 1. Open molding—corrosion-resistant...

2010-07-01

143

Short-term stress-corrosion-cracking tests for cast A27 steel and A36 steel weldments in simulated Hanford groundwater  

International Nuclear Information System (INIS)

Relatively short-term (approximately 2000 h) tests were conducted on precracked self-loaded fracture mechanics specimens of two candidate container materials in simulated Hanford groundwater at two temperatures: 1500C and 2500C. The two materials tested were cast ASTM A27 Grade 60-30 steel, and weldments in wrought ASTM A36 steel. Three different levels of applied stress intensity factors (K) were tested for each material/temperature combination. The results of these short-term tests suggested no crack extension in either material. In addition, short-term (1 week) load relaxation tests were conducted on precracked steels at 2500C. These results aid in the interpretation of test results for specimens tested for larger exposures in groundwater environments

144

Urinary casts  

Science.gov (United States)

... the kidney. They are seen in many kidney diseases. Renal tubular epithelial cell casts reflect damage to cells in the kidney called tubule cells. These casts are seen in conditions such as ... disease (such as CMV nephritis ), and kidney transplant rejection . ...

145

Influence of Fasciola Hepatica on Serum Biochemical Parameters and Vascular and Biliary System of Sheep Liver  

Directory of Open Access Journals (Sweden)

Full Text Available Background: The aim of this study was to evaluate the functional capacity of the liver based on the activity of specific enzymes and bilirubin in serum and also to investigate the influence of mechanical and toxic effects of Fasciola hepatica on the structures of the blood vessels and biliary tract in the sheep liver.Methods: Blood samples and liver of 63 indigenous sheep of Pramenka breed, slaughtered in the period from March to December 2009 were used. Based on parasitological findings in the liver, all animals were divided into two groups: control (n=34 and infected group (n=29. For investigation and description of pathological changes in sheep liver, naturally infected with F. hepatica, corrosion cast technique was used.Results: Biochemical analysis of tested parameters showed a significant elevation (P?0.05 of serum gamma-glutamyl transferase (GGT, total bilirubin (TBIL and direct bilirubin (DBIL in infected sheep group comparing with the control group. No significant differences were observed for activity of aspartate aminotranferase (AST between groups. Vascular and biliary systems of the liver were found to be affected.Conclusion: Results of biochemical analysis are consistent with pathological findings and measuring of tested parameters could be used in early diagnosis of sheep fasciolosis and to test the effectiveness of anthelmintic therapy. Corrosion cast technique is very useful for investigation of pathological changes and neoangiogenesis of vascular and biliary system in sheep liver, caused by mechanical and toxic effects of F. hepatica.

A Hodži?

2013-03-01

146

Salt Bath Oxinitriding of Gray Cast Iron  

Science.gov (United States)

Salt bath oxinitriding is a duplex surface treatment developed to improve tribological and corrosion properties of ferrous materials. In this research, gray cast iron samples were nitrided at the temperature range of 480°C-580°C, and then oxidized in an oxidative salt bath. The phase composition of surface layer was identified by X-ray diffraction. Using a microhardness tester, hardness of nitrided gray cast iron was measured. Corrosion behavior of treated (nitrided and oxinitrided) samples was evaluated using potentiodynamic polarization technique in 3.5% NaCl solution. XRD analyses indicate that the surface layer in nitrided and oxinitrided samples is composed of ?-iron nitride (Fe2-3N) and magnetite (Fe3O4), respectively. Results show that the corrosion resistance of gray cast iron can be improved up to 170%.

Ahmadi, M.; Teimouri, M.; Aliofkhazraee, M.; Mousavi Khoee, S. M.

147

Anodization of cast aluminium alloys produced by different casting methods  

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Full Text Available In this paper the usability of two casting methods, of sand and high pressure cast for the anodization of AlSi12 and AlSi9Cu3 aluminium cast alloys was investigated. With defined anodization parameters like electrolyte composition and temperature, current type and value a anodic alumina surface layer was produced. The quality, size and properties of the anodic layer was investigated after the anodization of the chosen aluminium cast alloys. The Alumina layer was observed used light microscope, also the mechanical properties were measured as well the abrasive wear test was made with using ABR-8251 equipment. The researches included analyze of the influence of chemical composition, geometry and roughness of anodic layer obtained on aluminum casts. Conducted investigations shows the areas of later researches, especially in the direction of the possible, next optimization anodization process of aluminum casting alloys, for example in the range of raising resistance on corrosion to achieve a suitable anodic surface layer on elements for increasing applications in the aggressive environment for example as materials on working building constructions, elements in electronics and construction parts in air and automotive industry.

K. Labisz

2008-08-01

148

Selected properties of new „duplex” cast steel  

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Full Text Available In this paper selected properties of new „duplex” cast steel are presented. The new cast steel was devised in HYDRO-VACUUM company in Grudzi?dz, where “duplex” cast steel for pump elements is smelted. The goal was to devise a new grade of “duplex” cast steel of better physicochemical properties and cheaper than now applied. It was demonstrated, that there is the possibility of devising the new grade of “duplex” cast steel. It is characterized by higher mechanical properties, similar wear resistance and greater corrosion resistance in 15% water solution of H2SO4 in comparison to now applied “duplex” cast steel. The chemical composition was selected to obtain in microstructure about of 50% ferrite and 50% austenite. It guarantee the highest properties and the lowest costs of its smelting.In the paper results of: the microstructure, Rm, Rp0,2, A5, HB, wear resistance and corrosion resistance in water solution of 15% HCl and H2SO4 acids of new cast steel was presented. They were compared with now applied in HYDRO-VACUUM company “duplex” cast steel.

S. Pietrowski

2011-10-01

149

Developing of chromium cast steel on sleeves of heavy machines  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The results of investigations of hardness, impact resistance, abrasive and corrosive wear of selected chromium cast steel with destination on sleeves of heavy machines were introduced in the article. First results of exploational investigations talked over on the end.

Kilarski, J.; Studnicki, A.; Suchon?, J.

2010-01-01

150

A scanning electron-microscopic, stereo-pair study of methacrylate corrosion casts of the mouse palatal and molar periodontal microvasculature.  

Science.gov (United States)

Microvascular beds of the palate, gingiva and periodontal ligament had interconnected but distinct, regional patterns. The palatal vasculature reflected mucosal-crest morphology: crestal capillary vessels of the rugae anastomosed with sagitally-orientated rows of 8 microns capillary loops, and, in the inter-rugal troughs, these formed a flat plexus overlying collecting veins more than 100 microns in diameter. Maxillary and mandibular molar ligaments had similar microvascular patterns. The molar gingiva had a circular, outer capillary and inner venous system linked by radial anastomoses. The outer (7 microns) capillaries enclosed the three molars in a continuous horizontal loop coursing beneath the crestal epithelium; the inner (10-15 microns) venous vessels encircled each molar just below the epithelial attachment. Glomerulus-like vascular formations, with an arterial and venous stalk, were associated with the inner circular system and extended toward the crevicular epithelium. Axially aligned, post-capillary, periodontal-ligament vessels (21 microns) anastomosed with the inner circular system, forming different patterns in the occlusal, middle and apical thirds. The apical pattern comprised an enveloping plexus of anastomosing venous vessels supplied by arterio-venous shunts; similar shunts were present throughout the ligament. The microvascular bed of the mandibular inter-radicular ligament was characterized by the presence of a large venous ampulla measuring 60 by 200 microns. Some regions of the ligament microvasculature drained via the medullary vessels into 50 microns-diameter venules located interdentally deep to the molar apices. Volumetrically, the ligament microvascular bed was predominantly of post-capillary venules, and morphologically, a paired arterial and venous system was not demonstrated. PMID:3479097

Wong, R S; Sims, M R

1987-01-01

151

Magnesium-lithium casting alloys  

Science.gov (United States)

The strength properties of magnesium-lithium alloys at room, low, and high temperatures are investigated. It is found that the alloys may have practical application at ambient temperatures up to 100 C, that negative temperatures have a favorable influence on the alloy strength, and that cyclic temperature variations have practically no effect on the strength characteristics. The influence of chemical coatings on corrosion resistance of the MgLi alloys is examined. Several facilities based on pressure casting machines, low-pressure casting machines, and magnetodynamic pumps were designed for producing MgLi alloy castings. Results were obtained for MgLi alloys reinforced with fibers having a volumetric content of 15%.

Latenko, V. P.; Silchenko, T. V.; Tikhonov, V. A.; Maltsev, V. P.; Korablin, V. P.

1974-01-01

152

The effect of recasting on corrosion of DUCINOX prosthetic alloy  

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Full Text Available The effect of recasting, up to two times, Ni-Cr (DUCINOX prosthetic alloy on its corrosion properties was carried out. The corrosion measurements were done in deoxygenated Fusayama Meyer artificial saliva solution at temperature of 37°C. In the study following electrochemical methods were used: measurement of free corrosion potential Ecor in open circuit, measurement of polarization resistance according to Stern-Geary's method and measurement of potentiodynamic characteristic in wide range of anodic polarization. In general, it can be stated that casting number weakly influence on corrosion properties of investigated alloy. At free corrosion potential there is no monotonic dependence of corrosion parameters versus casting number. However, at extreme anodic potentials monotonic changes of corrosion parameters with increasing casting number is observed. Obtained results and drawn conclusions are partially compatible with literature data.

L. Klimek

2009-07-01

153

On Tool Failure in Die Casting  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Die casting is a very cost-efficient method of forming thin-walled and complex near net-shaped products with close geometric tolerances and good surface finish. A permanent die tool is used to make large quantities of identical products. The performance and tool life are limited by several mechanisms, e.g. thermal fatigue cracking, erosion, and corrosion. To develop new and more resistant tool materials for die casting detailed knowledge of the actual casting conditions and the tool failure m...

Persson, Anders

2003-01-01

154

Tribological Properties of Al-SiC Metal Matrix Composites: A Comparison Between Sand Cast and Squeeze Cast Techniques  

Science.gov (United States)

Tribological behaviour of Al-SiC metal matrix composites prepared using two different fabrication techniques, viz. sand cast and squeeze cast techniques are studied in a multi- tribotester (TR-25, DUCOM, India) under dry sliding conditions and ambient atmosphere for varying volume fraction of reinforcement, applied load and sliding speed. Friction increases with increase in applied load and sliding speed and volume fraction of reinforcement. Wear test results show increased wear rates at higher load and speed, while increase in SiC volume fraction yields decrease in wear rate. Corrosion study conducted in 3.5 % NaCl solution shows that squeeze cast composites have better corrosion resistance than sand cast composites. Vickers's microhardness test shows improved hardness properties for squeeze cast composites compared to sand cast ones. The microstructure study of wear tracks reveals domination of abrasive wear with minor traces of adhesive wear.

Ghosh, S.; Sahoo, P.; Sutradhar, G.

2014-10-01

155

Automatic inspection of surface defects in die castings after machining  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new camera based machine vision system for the automatic inspection of surface defects in aluminum die casting was developed by the authors. The problem of surface defects in aluminum die casting is widespread throughout the foundry industry and their detection is of paramount importance in maintaining product quality. The casting surfaces are the most highly loaded regions of materials and components. Mechanical and thermal loads as well as corrosion or irradiation attacks are directed pri...

S?wi??o, S. J.; Perzyk, M.

2011-01-01

156

About some corrosion mechanisms of AZ91D magnesium alloy  

International Nuclear Information System (INIS)

The present work is dedicated to a study of the corrosion resistance of AZ91D (91% Mg) alloy in wet environments. Three industrial alloys obtained by die-casting or sand casting were subjected to salt spray corrosion tests (ASTM-B117 standard) and immersion tests. Weight loss kinetic curves were measured. Surface analysis was performed by X-ray photoelectron diffraction (XPS). After corrosion the sand cast alloy presents a surface mainly enriched in hydroxides and carbonates while the die-cast alloy presents a surface enriched also in mixed Mg-Al oxides. The quantitative analysis of the rate Mg/Al shows an enrichment in aluminium for the die-cast alloys in comparison to the sand cast alloy

157

Nodular cast iron and casting monitoring  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper quality monitoring of nodular cast iron and casting made of it is presented. A control system of initial liquid cast iron to spheroidization, after spheroidization and inoculation with using of TDA method was shown. An application of an ultrasonic method to assessment of the graphite form and the metal matrix microstructure of castings was investigated.

S. Pietrowski

2008-10-01

158

The influence of sigma phase on erosion and corrosion properties of duplex steel  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents the results of investigations concerning the influence of ? phase precipitating on the erosion and corrosion properties of ferritic-austenitic cast steel. The object of investigation have been two grades of corrosion-resistant cast steel: GX2CrNiMoCuN25-6-3-3 and GX2CrNiMoN25-6-3. The examinations have involved measurements for obtaining potentiodynamic curves, examination of erosion and corrosion resistance, and microstructural analysis. The supersaturated cast steel and the material after heat treatment have been examined. It has been found that the tribological properties of supersaturated cast steel are worse than those of the supersaturated and annealed cast steel. The highest erosion and corrosion resistance has been achieved as a result of ferrite decomposition ? ? ?’+ ?. The examinations of corrosion resistance have revealed that the ageing process after supersaturation do not cause significant changes in the anti-corrosive properties.

Z. Stradomski

2010-07-01

159

Casting materials  

Science.gov (United States)

A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.

Chaudhry, Anil R. (Xenia, OH); Dzugan, Robert (Cincinnati, OH); Harrington, Richard M. (Cincinnati, OH); Neece, Faurice D. (Lyndurst, OH); Singh, Nipendra P. (Pepper Pike, OH)

2011-06-14

160

Fabrication of bulk metallic glasses by centrifugal casting method  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The aim of the present work is characterization of the centrifugal casting method, apparatus andproduced amorphous materials, which are also known as bulk metallic glassesDesign/methodology/approach: The studied centrifugal casting system consists of two main parts: castingapparatus and injection system of molten alloy. The described centrifugal casting method was presented bypreparing a casting apparatus “CentriCast – 5”. The apparatus includes a cylindrical copper mold, which isrotated by a motor. The transmission allows to changing the speed of rotating mold.Findings: Bulk metallic glasses are a novel class of engineering materials, which exhibit excelent mechanical,thermal, magnetic and corrosion properties. Centrifugal casting is a useful method to produce bulk amorphousmaterials in form of rings, tubes or cylindrical parts. Presented centrifugal casting method and casting apparatushas been prepared to fabricate the samples of bulk metallic glass in form of rings with an outer diameter of 25mm and controlled thicknesses by changing the weight of the molten alloy.Research limitations/implications: Studied centrifugal casting method and casting apparatus has beenprepared to fabricate the samples of bulk metallic glass. For future research a characterization of microstructureand properties of prepared material will be performed.Practical implications: The centrifugal casting is a useful process to produce bulk amorphous materials in formof rings, tubes or graded amorphous matrix composites. It seems to be a very simple method, which allows toobtain BMG materials.Originality/value: The centrifugal casting method allows to produce bulk amorphous rings with thicknessabove 1-mm.

R. Nowosielski

2007-01-01

 
 
 
 
161

The ancient Chinese casting techniques  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the course of Chinese civilization, which lasted more than 5,000 years, casting production has made a huge contribution. In this paper, some representative metal castings were presented. According to their forming techniques, they can be grouped into stone mould casting, clay mould casting, ablation casting, lost wax casting, stack casting, permanent mould casting, sand casting, etc. According to their materials, they can be categorized into tin bronze, bimetallic bronze, malleable cast ir...

Tan Derui; Lian Haiping

2011-01-01

162

Characterization of the corrosion behaviour and solutions for the corrosion protection of Mg alloys  

Energy Technology Data Exchange (ETDEWEB)

Magnesium alloys offer a high potential for weight-saving in traffic systems and other applications. Furthermore, it is possible to reduce the production costs compared to aluminium if the die casting process is used. Nevertheless, some problems remain to be solved. One of them concerns the corrosion behaviour of magnesium alloys. This presentation surveys the current situation as to corrosion behaviour and protection of magnesium together with important criteria for interpretation after the corrosion tests and the proposal of new approaches for corrosion protection. (orig.)

Bommer, H. (Daimler-Benz AG, Muenchen (Germany))

1998-01-01

163

Final Report, Volume 1, Metallurgical Evaluation of Cast Duplex Stainless Steels and their Weldments  

Energy Technology Data Exchange (ETDEWEB)

Duplex stainless steels (DSS) are being specified for chloride containing environments due to their enhanced pitting and stress corrosion cracking resistance. They exhibit improved corrosion performance over the austenitic stainless steels. Duplex stainless steels also offer improved strength properties and are available in various wrought and cast forms. Selected grades of duplex stainless steel castings and their welds, in comparison with their wrought counterparts, were evaluated, regarding corrosion performance and mechanical properties and weldability. Multiple heats of cast duplex stainless steel were evaluated in the as-cast, solution annealed (SA) static cast and SA centrifugal cast conditions, while their wrought counterparts were characterized in the SA condition and in the form of as-rolled plate. Welding, including extensive assessment of autogenous welds and a preliminary study of composite welds (shielded metal arc weld (SMAW)), was performed. The evaluations included critical pitting temperature (CPT) testing, intergranular corrosion (IGC) testing, ASTM A923 (Methods A, B and C), Charpy impact testing, weldability testing (ASTM A494), ferrite measurement and microstructural evaluations. In the study, the corrosion performances of DSS castings were characterized and assessed, including the wrought counterparts for comparison. The evaluation filled the pore of lack of data for cast duplex stainless steels compared to wrought materials. A database of the pitting corrosion and IGC behavior of cast and wrought materials was generated for a greater depth of understanding for the behavior of cast duplex stainless steel. In addition, improved evaluation methods for DSS castings were developed according to ASTM A923, A262, G48 and A494. The study revealed that when properly heat treated according to the specification, (1) DSS castings have equal or better pitting and intergranular corrosion resistance than their wrought counterparts; (2) Welding reduces the pitting and intergranular corrosion resistance for both the wrought and cast duplex alloys; (3) Castings generally have better toughness than their wrought counterparts in the temperature range of �������¢����������������80���������������°C to +20���������������°C; (4) All shield metal arc (SMA) test welds in DSS castings, with recommended or over matching filler metal, indicate that welding is not a significant factor when considering DSS applications.

Wen, Songqing; Lundin, Carl, W.; Batten, Greg, W.

2005-09-30

164

Final Report, Volume 1, Metallurgical Evaluation of Cast Duplex Stainless Steels and their Weldments  

Energy Technology Data Exchange (ETDEWEB)

Duplex stainless steels (DSS) are being specified for chloride containing environments due to their enhanced pitting and stress corrosion cracking resistance. They exhibit improved corrosion performance over the austenitic stainless steels. Duplex stainless steels also offer improved strength properties and are available in various wrought and cast forms. Selected grades of duplex stainless steel castings and their welds, in comparison with their wrought counterparts, were evaluated, regarding corrosion performance and mechanical properties and weldability. Multiple heats of cast duplex stainless steel were evaluated in the as-cast, solution annealed (SA) static cast and SA centrifugal cast conditions, while their wrought counterparts were characterized in the SA condition and in the form of as-rolled plate. Welding, including extensive assessment of autogenous welds and a preliminary study of composite welds (shielded metal arc weld (SMAW)), was performed. The evaluations included critical pitting temperature (CPT) testing, intergranular corrosion (IGC) testing, ASTM A923 (Methods A, B and C), Charpy impact testing, weldability testing (ASTM A494), ferrite measurement and microstructural evaluations. In the study, the corrosion performances of DSS castings were characterized and assessed, including the wrought counterparts for comparison. The evaluation filled the pore of lack of data for cast duplex stainless steels compared to wrought materials. A database of the pitting corrosion and IGC behavior of cast and wrought materials was generated for a greater depth of understanding for the behavior of cast duplex stainless steel. In addition, improved evaluation methods for DSS castings were developed according to ASTM A923, A262, G48 and A494. The study revealed that when properly heat treated according to the specification, (1) DSS castings have equal or better pitting and intergranular corrosion resistance than their wrought counterparts; (2) Welding reduces the pitting and intergranular corrosion resistance for both the wrought and cast duplex alloys; (3) Castings generally have better toughness than their wrought counterparts in the temperature range of -80 C to +20 C; (4) All shield metal arc (SMA) test welds in DSS castings, with recommended or over matching filler metal, indicate that welding is not a significant factor when considering DSS applications.

Wen, Songqing; Lundin, Carl, W.; Batten, Greg, W.

2005-09-30

165

Phase Transformation in Cast Superaustenitic Stainless Steels  

Energy Technology Data Exchange (ETDEWEB)

Superaustenitic stainless steels constitute a group of Fe-based alloys that are compositionally balanced to have a purely austenitic matrix and exhibit favorable pitting and crevice corrosion resistant properties and mechanical strength. However, intermetallic precipitates such as sigma and Laves can form during casting or exposure to high-temperature processing, which degrade the corrosion and mechanical properties of the material. The goal of this study was to accurately characterize the solid-solid phase transformations seen in cast superaustenitic stainless steels. Heat treatments were performed to understand the time and temperature ranges for intermetallic phase formations in alloys CN3MN and CK3MCuN. Microstructures were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy and wavelength dispersive spectroscopy (EDS, WDS). The equilibrium microstructures, composed primarily of sigma and Laves within purely austenitic matrices, showed slow transformation kinetics. Factors that determine the extent of transformation, including diffusion, nucleation, and growth, are discussed.

Nathaniel Steven Lee Phillips

2006-12-12

166

Wear resistant steels and casting alloys containing niobium carbide  

Energy Technology Data Exchange (ETDEWEB)

Niobium, like titanium and vanadium, forms superhard MC carbides that remain relatively pure in technical alloys on account of their low solubility for other metallic alloying elements. However, because they have a greater hardness than the precipitated chromium carbides commonly used in wear-resistant alloys, they are suitable as alternative hard phases. This contribution deals with new wear-resistant steels and casting alloys containing niobium carbide. These include a secondary hardening hardfacing alloy, a composite casting alloy for wear applications at elevated temperatures, a white cast iron as well as two variants of a corrosion-resistant cold-work tool steel produced by melt metallurgy and by powder metallurgy. A heat-resistant casting alloy is also discussed. Based on equilibrium calculations the microstructures developing during production of the alloys are analysed, and the results are discussed with respect to important properties such as abrasive wear and corrosion resistance. (orig.)

Theisen, W.; Siebert, S.; Huth, S. [Lehrstuhl Werkstofftechnik, Ruhr-Univ. Bochum (Germany)

2007-12-15

167

Moldless casting by laser  

Science.gov (United States)

The principle of laser cladding involves the use of high power carbon-dioxide lasers and powder deposition technology to provide wear and corrosion resistant surface coatings to engineering components. By injecting metal powder into a laser generated melt pool on a moving substrate a solidified metal track can be produced. Deposition of successive tracks produces a multi-layer build. Laser direct casting (LDC) utilizes a coaxial nozzle enabling consistent omnidirectional deposition to produce 3D components from a selection of metal powders. The influence of the principal process parameters over the process features namely, powder catchment efficiency, beam shape and build rates are presented with several successfully generated 3D components. Nickel, stainless steel and satellite powders were deposited at laser powders of 0.4 to 1.4 kW and speeds of 500 to 1000 mm/min achieving build rates of 3 to 9 mm3/s. Fully dense metallurgical structures have been produced with no cracking or porosity and powder catchment efficiencies up to 85% have been achieved.

McLean, Marc A.; Shannon, G. J.; Steen, William M.

1997-09-01

168

Vascular Depression  

Directory of Open Access Journals (Sweden)

Full Text Available Research until today has found a positive relationship between vascular risk factors and depression. With the advance in neuroimaging methods in the last years, a more definite relation between cerebrovascular diseases and old-age depression have been described, and in the light of the studies in this field, a ‘vascular depression’ subtype has been defined. According to this hypothesis, ‘vascular depression’ implies a special depression subtype which begins first time in old age, which is accompanied less by depressive mood, characterized by impairment in cognitive abilities, especially in executive functions, dominated by psychomotor retardation and somatic symptoms, and lack of family history of depression. A group of researchers stated that defining vascular depression only with clinical findings would be insufficient, suggested brain imaging findings are required for the diagnosis, and subcortical hyperintensities are related to depression symptoms. Late-onset depression is shown to be related to frontal subcortical white-matter hyperintensities, and these findings were found to be correlated with affect dysregulation and executive dysfunction in late-life depression. Executive dysfunction as well as memory and attention problems in late-onset depression have been shown in different studies. Thus, vascular depression hypothesis is thought to be related with subcortical dementia upon these findings. There is currently no consensus on the concept of vascular depression and diagnostic criteria. But this concept which is explaining a subgroup of late-life depressions, predicting the treatment outcome, and implying a preventable disease with the control of vascular factors, makes vascular depression a very important topic. In this review, research on vascular depression hypothesis, findings and critics about the concept will be reviewed.(Arc­hi­ves of Neu­ropsy­chi­atry 2013; 50: 1-8

Yunus Emre Sönmez

2013-03-01

169

High Cr white cast iron/carbon steel bimetal liner by lost foam casting with liquid-liquid composite process  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Liners in wet ball mill for mineral processing industry must bear abrasive wear and corrosive wear, and consequently, the service life of the liner made from traditional materials, such as Hadfield steel and alloyed steels, is typically less than ten months. Bimetal liner, made from high Cr white cast iron and carbon steel, has been successfully developed by using liquid-liquid composite lost foam casting process. The microstructure and interface of the composite were analyzed using optical m...

Xiao Xiaofeng; Ye Shengping; Yin Weixin

2012-01-01

170

Influence of the casting temperature on dental Co-base alloys properties  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: The goal of the study is to find the relationship between the value of casting temperature on corrosion resistance, hardness and mechanical properties of two Co-Cr-Mo alloys Remanium 2000+ and Wirobond LFC used in dentistry.Design/methodology/approach: Realized investigations starts from preparing the mould and cast two CoCrMo alloys in 1430, 1440, 1450 and 1460°C. Electrochemical corrosion research were made in water centre which simulated artificial saliva environment, by recordin...

Reimann, L.; Dobrzan?sk, L. A.

2013-01-01

171

The corrosion resistance of two non-noble alloys  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nickel-chromium and cobalt-chromium alloys are commonly used for crown and bridge castings. These non-noble dental alloys are much cheaper than noble dental alloys but on the other hand they have disadvantages related to their lower corrosion resistance and corrosion products (released ions), some of them recognized as toxic ions that may cause allergies and other oral pathologies. Therefore it is important to evaluate the corrosion behaviour of such alloys. This study aims to evaluate the...

Capelo, Sofia; Fernandes, Jcs; Proenc?a, L.; Fonseca, Ite

2013-01-01

172

High temperature corrosion of metals  

International Nuclear Information System (INIS)

This paper covers three main topics: 1. high temperature oxidation of metals and alloys, 2. corrosion in sulfur containing environments and 3. structural changes caused by corrosion. The following 21 subjects are discussed: Influence of implanted yttrium and lanthanum on the oxidation behaviour of beta-NiA1; influence of reactive elements on the adherence and protective properties of alumina scales; problems related to the application of very fine markers in studying the mechanism of thin scale formation; oxidation behaviour of chromia forming Co-Cr-Al alloys with or without reactive element additions; growth and properties of chromia-scales on high-temperature alloys; quantification of the depletion zone in high temperature alloys after oxidation in process gas; effects of HC1 and of N2 in the oxidation of Fe-20Cr; investigation under nuclear safety aspects of Zircaloy-4 oxidation kinetics at high temperatures in air; on the sulfide corrosion of metallic materials; high temperature sulfide corrosion of Mn, Nb and Nb-Si alloys; corrosion behaviour or NiCrAl-based alloys in air and air-SO2 gas mixtures; sulfidation of cobalt at high temperatures; preoxidation for sulfidation protection; fireside corrosion and application of additives in electric utility boilers; transport properties of scales with complex defect structures; observations of whiskers and pyramids during high temperature corrosion of iron in SO2; corrosion and creep of alloy 800H under simulated coal gasification conditions; microstructural changes of HK 40 cast alloy caused by exploitation in tubes in steam reformer installation; microstructural changes during exposure in corrosive environments and their effect on mechanical properties; coatings against carburization; mathematical modeling of carbon diffusion and carbide precipitation in Ni-Cr-based alloys. (MM)

173

Fatigue Assessment of Cast Components : Influence of Cast Defects  

Digital Repository Infrastructure Vision for European Research (DRIVER)

 This thesis is on the fatigue assessment of cast components with special attention to defects. The primary material in view is nodular cast iron, but also cast steel is considered. However, the fatigue behaviour is in principle valid for general use on other cast metals.The first two papers is about general cast material behaviour in fatigue loading. The materials considered are a high strength alloyed cast steel and a medium strength nodular cast iron. It is concluded that cast defects is ...

Bjo?rkblad, Anders

2008-01-01

174

Exploitation of rare earth metals in cast steel production for power engineering  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents results of experiments carried out on industrial melts. There has been tested the REM influence on carbon properties (0.20%C as well as austenitic cast steel Cr-Ni 18/8+Ti type.It was found that REM cause an essential improvement of cast steels impact strength and in case of austenitic cast steel – also the corrosion resistance improvement in boiling 65%HNO3 (Huey test.

J. Kasi?ska

2008-12-01

175

Exploitation of rare earth metals in cast steel production for power engineering  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper presents results of experiments carried out on industrial melts. There has been tested the REM influence on carbon properties (0.20%C) as well as austenitic cast steel Cr-Ni 18/8+Ti type.It was found that REM cause an essential improvement of cast steels impact strength and in case of austenitic cast steel – also the corrosion resistance improvement in boiling 65%HNO3 (Huey test).

Kasin?ska, J.; Gajewski, M.

2008-01-01

176

Aluminide protective coatings on high–temperature creep resistant cast steel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents the results of research on aluminide protective coatings manufactured on high–temperature creep resistant cast steel. The main purpose of these coatings is protection against the high temperature corrosion, especially at high carburizing potential atmosphere. Coatings were obtained on cast steel type G–XNiCrSi36–18 with the following methods: pack cementation, paste method, cast method and slurry cementation. The phase composition, thickness and morphology of coating...

Kubicki, J.; Kochman?ska, A.

2009-01-01

177

Bimetallic layer castings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: In paper is presented technology of bimetallic layer casting in configuration: working part (layer) from ferritic or austenitic alloy steel and bearing part from grey cast iron.Design/methodology/approach: In applied technology surface layer on the basis of alloy steel at 2 or 5mm thickness was put directly in founding process of cast iron with use of preparation of mould cavity method. Quality of bimetallic layer castings was estimated on the base of ultrasonic non-destructive testi...

Cholewa, M.; Wro?bel, T.; Tenerowicz, S.

2010-01-01

178

LLNL casting technology  

Science.gov (United States)

Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US competiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience casting metals and nonmetals; advanced measurement and instrumentation systems. Department of Energy (DOE) funding provides the leverage for LLNL to collaborate with industrial partners to share this advanced casting expertise and technology. At the same time, collaboration with industrial partners provides LLNL technologists with broader insights into casting industry issues, casting process data, and the collective experience of industry experts. Casting R&D is also an excellent example of dual-use technology; it is the cornerstone for increasing US industrial competitiveness and minimizing waste nuclear material in weapon component production. Annual funding for casting projects at LLNL is $10M, which represents 1% of the total LLNL budget. Metal casting accounts for about 80% of the funding. Funding is nearly equally divided between development directed toward US industrial competitiveness and weapon component casting.

Shapiro, A. B.; Comfort, W. J., III

1994-01-01

179

High quality casting materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: The paper briefly presents results of the new developed high quality cast materials.Design/methodology/approach: The following materials are: hypereutectoid cast steel with various microstructure modular graphite obtained in as-cast condition (raw state), ductile cast iron of bainite-martensitic carbides structure obtained in a raw state, aluminum bronzes and silumins with additives of: chromium, molybdenum, wolfram, vanadium.Findings: These alloys are characterized primarily by sign...

Pietrowski, S.

2010-01-01

180

CASTE FRAMEWORK AT NATIONAL LEVEL  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Caste is an important element of the Indian political process. It is legitimate. Caste has been inequality creating in Indian society. Therefore its influence on power shaping & Policy Making process. In this sense caste element has got sphere of influence in political process. Relationship between Caste & politics has been more eminent. Caste has been influencing on politics & politics has been influenced by caste. Limitation of Dominant caste at national level: dominant caste has been deman...

PRAKASH PAWAR

2013-01-01

 
 
 
 
181

Egyptian Caste System  

Science.gov (United States)

Understand the culture, character, and societal characteristics of different classes in the ancient Egyptian caste system Understand the culture, character, and societal characteristics of different classes in the ancient Egyptian caste system Go to these sites to learn about the Egyptian Caste System ...

Issen, Ms.

2009-09-17

182

Corrosion Engineering.  

Science.gov (United States)

A description is provided for a Corrosion and Corrosion Control course offered in the Continuing Engineering Education Program at the General Motors Institute (GMI). GMI is a small cooperative engineering school of approximately 2,000 students who alternate between six-week periods of academic study and six weeks of related work experience in…

White, Charles V.

183

Fireside Corrosion  

Energy Technology Data Exchange (ETDEWEB)

Oxy-fuel fireside research goals are: (1) determine the effect of oxyfuel combustion on fireside corrosion - flue gas recycle choice, staged combustion ramifications; and (2) develop methods to use chromia solubility in ash as an ash corrosivity measurement - synthetic ashes at first, then boiler and burner rig ashes.

Holcomb, Gordon

2011-07-14

184

Primary Crystallization of High Chromium Cast Steel in Metastable Conditions  

Directory of Open Access Journals (Sweden)

Full Text Available The analysis of the primary crystallization of wear corrosive-erosive high chromium cast steel was introduced in the article on the basis of investigations the widened method of the differential thermal analysis with testers DTA-C and DTA-Is. The use of these testers enabled the analysis of crystallization for the various rates of cooling.

A. Studnicki

2012-12-01

185

Developing of chromium cast steel on sleeves of heavy machines  

Directory of Open Access Journals (Sweden)

Full Text Available The results of investigations of hardness, impact resistance, abrasive and corrosive wear of selected chromium cast steel with destination on sleeves of heavy machines were introduced in the article. First results of exploational investigations talked over on the end.

J. Kilarski

2010-10-01

186

Primary Crystallization of High Chromium Cast Steel in Metastable Conditions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The analysis of the primary crystallization of wear corrosive-erosive high chromium cast steel was introduced in the article on the basis of investigations the widened method of the differential thermal analysis with testers DTA-C and DTA-Is. The use of these testers enabled the analysis of crystallization for the various rates of cooling.

Studnicki, A.; Kondracki, M.; Szajnar, J.

2012-01-01

187

The influence of sigma phase on erosion and corrosion properties of duplex steel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper presents the results of investigations concerning the influence of ? phase precipitating on the erosion and corrosion properties of ferritic-austenitic cast steel. The object of investigation have been two grades of corrosion-resistant cast steel: GX2CrNiMoCuN25-6-3-3 and GX2CrNiMoN25-6-3. The examinations have involved measurements for obtaining potentiodynamic curves, examination of erosion and corrosion resistance, and microstructural analysis. The supersaturated cast steel and ...

Stradomski, Z.; Brodziak, A.

2010-01-01

188

EFFECT OF THE HEAT AND SURFACE LASER TREATMENT ON THE CORROSION DEGRADATION OF THE Mg-Al ALLOYS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper there is presented the corrosion behavior of the cast magnesium alloys as cast state, after heat and laser treatment. Pitting corrosion resistance of the analyzed alloys was carried out using the potentiodynamic electrochemical method (direct current), based on a anodic polarization curve. On the basis of the achieved anodic polarization curves, using the Tefel extrapolation method near to the corrosion potential, the quantitative data were determined, which describe the electro...

Dobrzan?ski, Leszek A.; Tomasz Ta?ski; Szymon Malara

2011-01-01

189

Improved cast stainless steels for shield module applications  

International Nuclear Information System (INIS)

Full text of publication follows: Casting of austenitic stainless steels offers the possibility of directly producing large and/or relatively complex structures, such as the first wall shield modules or the divertor cassette for the International Tokamak Experimental Reactor (ITER). Casting offers major cost savings when compared to fabrication via welding together quarter modules machined from large forgings. However, because of the large grain size, low dislocation density and extensive segregation of alloying elements, the strength properties of such cast components are frequently inferior to those of conventionally forged and annealed components. To improve and validate cast stainless steel as a substitute for wrought stainless steel for shield module applications, a series of test cast steels based on the commercially available CF3M specification have been designed and fabricated. These modifications utilize combinations of Mn and N,which are expected to synergistically result in significant increases in strength. In addition, two other alloys will enhance solid solution strengthening with Cu and W additions to increase strength. It will be necessary to demonstrate that these compositional modifications do not adversely affect performance in the ITER water corrosion and radiation environments Computational thermodynamics and solidification modeling predict that these improved cast steel compositions to be fully austenitic throughout the solidification process. Po throughout the solidification process. Post-cast heat treatments are a second-route for improving strength and properties of cast materials. Homogenizing treatments to remove second particles have also been explored as means of improving strength in cast stainless steel. In this paper, the physical metallurgy, mechanical properties, and irradiation tolerance of the improved cast stainless steel compositions and heat treatments will be compared to standard cast stainless steel. Fracture toughness, weldability, and non-destructive analysis of the improved cast stainless steel will also be discussed. This work was supported by the US-ITER program. (authors)

190

Corrosion and corrosivity monitoring system  

Science.gov (United States)

Honeywell International has developed and flight-tested a Corrosion and Corrosivity Monitoring System (C2MS). The C2MS detects galvanic corrosion in the main gearbox feet fasteners of helicopters. In addition, it monitors the environmental conditions inside the main floorboard compartment to determine the need for structural maintenance. The C2MS sensor on a main gearbox feet fastener sends a small electrical signal through the fastener and housing to measure the conductivity of the assembly. The measured conductivity value is used to determine if galvanic corrosion is present in the fastener assembly. The floorboard compartment sensors use a surrogate metal coupon to measure the corrosivity of the environment. The information from this sensor is used to recommend an extension to the calendar-based maintenance schedule. Fleet-wide information can be gathered by the system. The C2MS uses two Data Collection Units (DCUs) to store the corrosion data: one for the main gearbox feet fasteners and one for the main floorboard compartment. The DCU design addresses the issues of long battery life for the C2MS (greater than 2 years) and compactness. The data from the DCUs is collected by a personal digital assistant and downloaded to a personal computer where the corrosion algorithms reside. The personal computer display provides the location(s) of galvanic corrosion in the main gearbox feet fasteners as well as the recommended date for floorboard compartment maintenance. This paper discusses the methodology used to develop the C2MS software and hardware, presents the principles of the galvanic corrosion detection algorithm, and gives the laboratory and flight test results that document system performance in detecting galvanic corrosion (detection and false alarm rate). The paper also discusses the benefits of environmental sensors for providing a maintenance scheduling date.

Braunling, Russ; Dietrich, Paul

2005-05-01

191

Vascular Access for Hemodialysis  

Science.gov (United States)

... Kidney Failure Series : Vascular Access for Hemodialysis Vascular Access for Hemodialysis On this page: What is a ... the Kidney Failure Series What is a vascular access? A vascular access is a hemodialysis patient’s lifeline. ...

192

Evaluation of microstructural effects on the corrosion behaviour of AZ91D magnesium alloy  

DEFF Research Database (Denmark)

The effect of microconstituents on the corrosion and electrochemical behaviour of AZ91D alloy prepared by die-casting and ingot casting route has been investigated in 3.5% NaCl solution at pH 7.25. The experimental techniques used include constant immersion technique, in-situ corrosion monitoring, and potentiodynamic polarisation experiments. Surface examination and analytical studies were carried out using optical and scanning electron microscopy, EDX and XRD. The corrosion behaviour of microconstituents namely primary alpha, eutectic alpha and beta phases was significantly different. Goring of aluminum showed influence on corrosion behaviour more significantly in ingot material. Areas with aluminium concentration less than about 8% were found to be prone to corrosion attack compared with either those with higher amount of aluminium or beta phase. Die-cast material with smaller grain size and fine beta phase offered marginally lower corrosion rate and better passivation compared with the ingot. In die-cast and ingot, hydrogen evolution took place preferentially on beta phase. XRD pattern of non-corroded and corroded surface revealed the removal of beta phase from alloy surface during corrosion. The corrosion products for ingot consisted of Mg(OH)(2) with small amounts beta phase, magnesium-aluminum oxide and MgH2 while for die-cast, the product showed a highly amorphous structure. (C) 2000 Elsevier Science Ltd. All rights reserved.

Ambat, Rajan; Aung, Naing Naing

2000-01-01

193

Vascular sarcomas.  

Science.gov (United States)

Vascular sarcomas are soft-tissue tumors that arise from the endothelium with a malignant potential. This review discusses the management of epithelioid hemangioendothelioma (EHE) and angiosarcoma. EHE is a vascular tumor of intermediate malignant potential with an indolent course. EHE arising from the liver, lung, or bone tends to be multifocal and the rate of progression is slow and often unpredictable. Treatment should be considered in patients with significant symptomatic deterioration and/or progressive disease on imaging studies. Various cytotoxic and targeted therapies are available for management, with disease stabilization as the most common outcome. Angiosarcoma is an aggressive vascular tumor with a high malignant potential. Multidisciplinary care is critical for the management of localized disease, and the best outcomes are often observed in patients when a combination of systemic and local therapy options is used. Metastatic angiosarcoma is treated primarily with systemic therapy, and several cytotoxic and targeted therapies are available, alone or in combination. The choice of therapy depends on several factors, such as cutaneous location of the tumor, performance status of the patient, toxicity of the treatment, and patient goals. PMID:23852636

Ravi, Vinod; Patel, Shreyaskumar

2013-08-01

194

Expandable pattern casting research  

Science.gov (United States)

The Expandable Pattern Casting (EPC) Process is a developing foundry technology that allows designers the opportunity to consolidate parts, reduce machining, and minimize assembly operations. An air gauging system was developed for measuring foam patterns; exact shrinkage depended on type and density of the foam. Compaction studies showed that maximum sand densities in cavities and under overhangs are achieved with vibrational amplitudes 0.001-0.004 in., and that sand moved most freely within a few inches of the top free surface. Key to complete mold filling while minimizing casting defects lies in removing the foam decomposition products. The most precise iron castings were made by EPC in four commercial EPC foundries, with attention paid to molding and compaction. EP cast 60-45-12 ductile iron had yield strengths, ultimate strengths, and elastic modulus similar to conventionally cast ductile iron cast from the same ladle.

1993-09-01

195

Die casting plutonium  

International Nuclear Information System (INIS)

A successful method of die casting plutonium is described. The method is an improvement over conventional pour-cast techniques in that the plutonium can be solidified more rapidly. One advantage of rapid solidification is that cast structures can be improved. Another advantage is that the plutonium has little time to react with its surroundings, so experimenters can choose from a larger selection of die construction materials

196

New casting coatings  

International Nuclear Information System (INIS)

In this project the results of the researches about the influence of the four types of ceramic coatings of the evaporating patterns (on the basis of talc, mullite, zircon and cordierite) on the talc of the Lost Foam process and the castings quality are presented. For the valid evaluation of the results, some parallel examinations of the quality of castings obtained by casting in sand were carried out. (Original)

197

Casting in Sport  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Attempts by sports medicine professionals to return high school athletes with hand and wrist injuries to competition quickly and safely have been the source of confusion and debate on many playing fields around the country. In addition to the differing views regarding the appropriateness of playing cast usage in high school football, a debate exists among sports medicine professionals as to which material is best suited for playing cast construction. Materials used in playing cast constructio...

Decarlo, Mark; Malone, Kathy; Darmelio, John; Rettig, Arthur

1994-01-01

198

Quality control of cast brake discs  

Directory of Open Access Journals (Sweden)

Full Text Available The largest industrial application so far have the gray cast irons which are characterized by low tensile and bending strength, while at the same time they have good ultimate comprehensive strength. Additionally, the fatigue strength of gray cast irons is comparatively low and they are only to some extend sensitive for the surface waters effects. Cast iron is the material, which is comparatively easy to be processed, and for this reason – it is not expensive. Brake discs are exploited in particularly hard conditions. They must be resistant both against the thermal fatigue and abrasion wearing (at dry friction as well as against seizing, corrosion and mechanical load [1-3]. The gray cast iron, better than other materials, fulfills all the requirements necessary for making the material for the casts resistant against such tough conditions. This work reflects the researches aiming to define the quality of cast brake discs (ventilated and non-ventilated ones upon a period of their exploitation in real conditions. The following researches were performed: evaluations of the disc surface condition, measurement of disc thickness, examination of run – out flank and metallographic analysis. In order to more detailed recognition of mechanisms and reasons of brake discs wearing in real conditions, one should conduct additional examinations: computer analysis of the microstructure, chemical composition analysis, etc., as well as study of the technology of their production in foundries, where they are manufactured [4]. By obtaining the full set of the mentioned above data one can draw final conclusions and remove causes of possible defects.

M. Stawarz

2008-04-01

199

Fatigue - corrosion of endoprosthesis titanium alloys.  

Science.gov (United States)

Commercial total hip prostheses often show certain metallurgical faults (porosities, coarse grains, growth dendrites, carbide networks). In order to investigate more accurately the role played by these different parameters in prostheses failure we performed a large number of systematic corrosion, fatigue and fatigue - corrosion tests on these materials and on commercial total hip prostheses. Ultimate strengthes seem to be reached for cast cobalt alloys, whereas titanium alloys, such as Ta 6 V, present very high fatigue limit under corrosion. Thus, rotative bending fatigue - corrosion tests in biological environment provide values about 50 DaN/mm2. This value, is nevertheless appreciably higher than those obtained with stellites and stainless steel. Titanium alloys, because of their mechanical performances, their weak Young's modulus (11000 DaN/mm2) and their relative lightness (4.5. g/cm3), which are associated with a good biocompatibility, seem very promising for permanent implants realisation. PMID:454780

Cornet, A; Muster, D; Jaeger, J H

1979-01-01

200

Multi-layers castings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In paper is presented the possibility of making of multi-layers cast steel castings in result of connection of casting and welding coating technologies. First layer was composite surface layer on the basis of Fe-Cr-C alloy, which was put directly in founding process of cast carbon steel 200–450 with use of preparation of mould cavity method. Second layer were padding welds, which were put with use of TIG – Tungsten Inert Gas surfacing by welding technology with filler on Ni matrix, Ni and...

Szajnar, J.; Wro?bel, P.; Wro?bel, T.

2010-01-01

 
 
 
 
201

Evolution of halictine castes  

Science.gov (United States)

Social halictine bees have female castes that range from species with no size differences to those with a discrete bimodality. Female caste differences are inversely correlated with the number of males produced in the first brood. It is proposed that the sexual dimorphism of solitary forms is being usurped by the female caste system of species in the process of turning social. Thus, caste differences and summer male suppression are greatest in the social species originating from solitary precursors with distinct sexual dimorphism, and are least in species evolving from solitary ancestors with a continuous sexual polymorphism.

Knerer, Gerd

1980-03-01

202

PLANT DIVERSITY OF THE ZHELTOKAMENSKIY OPEN CAST MINES  

Directory of Open Access Journals (Sweden)

Full Text Available Floristic structure data of soil algae, lichens, mosses, and vascular plants are given. Rare plant species which are protected at the Ukrainian, European, and International levels were revealed. The species list of trees and bushes was conducted. The soil analysis was carried out by such parameters: pH-value, the maintenance of hygroscopic water, the maintenance of mineral substances. Vegetation biomass on the open cast mines sample areas is defined. Ecological analysis of the biotopes of registered algae species was performed. The ecological analysis of the vascular plants species biotopes was carried out.The estimation of the perspective vegetation pattern was suggested for natural restoration of the open cast mines. The plant species are selected according to the ecological and morphological characteristics for plant rehabilitation and planting of open cast mines.

Yarova T.A.

2012-11-01

203

[Studies on titanium casting. (1) Influence of the mold temperature on titanium castings].  

Science.gov (United States)

Pure titanium and titanium alloys have excellent biocompatibility, excellent corrosion tarnish resistance, a quarter of the specific gravity of gold base alloys and suitable mechanical properties for dental clinical use. However, titanium has some undesirable characteristics. For example, it has a high melting temperature and chemical reactivity at high temperatures. The investigate influence of the mold temperature on castability and mechanical properties of the titanium castings was study. The castability was found to be good at various mold temperatures, but the higher the mold temperature during casting, the greater the adhesive phenomenon between titanium surface and the investment. From the EPMA observation of the surface layer on the titanium castings, an Si- rich layer whose thickness increased considerably with increasing temperature was observed. The Vickers hardness in the surface layer was greater than that in the inner part. At a higher mold temperature during casting the thickness of the high Vickers hardness layer was increased. There was a relationship between the Vickers hardness value and the thickness of Si rich layer. In the tensile strength test of titanium castings, elongation values decrease and tensile strength values increased with the rise in mold temperature. PMID:2135519

Kuroiwa, A; Wada, K; Hibino, Y; Yoshida, O; Kakumoto, Y; Kouchi, H; Nagayama, K; Hashimoto, H

1990-03-01

204

Effect of Al additions and heat treatment on corrosion properties of Mg-Al based alloys  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: In this paper there is presented the corrosion behavior of cast magnesium alloys in as cast state and after heat treatment.Design/methodology/approach: The following results concern scanning electron microscopy investigations in the SE as well BSE observation mode, for better phase contrast results, also qualitative microanalysis was applied for chemical composition investigations of the surface. Pitting corrosion resistance was carried out using the potentiodynamic electrochemical m...

Dobrzan?ski, L. A.; Labisz, K.; Tan?ski, T.

2011-01-01

205

Closed aluminium skeleton casting  

Directory of Open Access Journals (Sweden)

Full Text Available In this miclc authors showcd method for rnanuraauring of skeleton castings with continuous cxtcmal surfacc. Wall lhickncss of thcexternal surface was 6 mm. Thc cxprirnental casting was rnanulacturcd in order to verify lhc rcsults of fitling mould cavity which wcreohtaincd by numerical simu tation. Thc alurninosilicarc core was ad to pducc cxpcrimntal aluminum skelaon castings wilhdimensions or (1 15x65~13 6 mm. Expximental casting was manufactured with elevated temperature of mwld (370 K. Luwcr andstotrcd ingalc with high gcting sysicm (300mm was usd. Analysis of ability of metal to fill rhe mould cavity in esrablish tcchnologicalconditions was jxrfomcd. Dcgm of tclincrncnt OF structure in typicall rcgion of skctcton casting was compared. Qualitative diffccrentdcgrcc of fineness of cuteetic was confirmed. Sclcction of mDdification conditions AlSi alloy of skclcton casting is nmssary.Thc manufacturing af skclcron casting in establish tcchnological conditions enables obtained vcry gdfil ling or mould cavity andsuitable cxtcrnaE gmmctrical form of casting.

M. Dziuba-Ka?u?a

2008-03-01

206

Continuous casting method  

International Nuclear Information System (INIS)

The steel to be cast is SUS 304 stainless steel containing 0.4 to 2.0mass% B boron to be used for cells of a spent fuel rack of a nuclear power plant. The conditions for casting are such that casting speed is from 0.4 to 0.8 m/min, the gap of support rolls in a secondary cooling region in the direction of casting is 300mm or less, and a ratio of solid phase in the central portion of the thickness of the cast piece passing through the final portion of the second cooling region is 0.2 or less. A desired lower limit between the support rolls is about 150mm. If the casting speed is less than 0.4m/min, the ratio of the solid phase at the central portion of the thickness of the cast piece at the final position of the secondary cooling region can not be reduced to 0.2. If the ratio of the solid phase exceeds 0.2, porosities are formed. The lower limit of the ratio of the solid phase is about 0.05. With such a constitution, cast pieces with no surface and internal defects can be manufactured without forming break out. (I.N.)

207

Higher Education's Caste System  

Science.gov (United States)

In this article, the author discusses the history of the present caste system in higher education. He shows how the public's perception of this caste system is based on image and not usually on the quality of teaching and curriculum in colleges and universities. Finally, he discusses a model for accessibility to higher education and how higher…

Iannone, Ron

2004-01-01

208

Cast iron - a predictable material  

Digital Repository Infrastructure Vision for European Research (DRIVER)

High strength compacted graphite iron (CGI) or alloyed cast iron components are substituting previously used non-ferrous castings in automotive power train applications. The mechanical engineering industry has recognized the value in substituting forged or welded structures with stiff and light-weight cast iron castings. New products such as wind turbines have opened new markets for an entire suite of highly reliable ductile iron cast components. During the last 20 years, casting process s...

Sturm, Jorg C.; Guido Busch

2011-01-01

209

Color Casts Detection and Adjustment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a new method for detection and adjustment color cast. Using the neural network to detect color cast and classify images into three subsets: no cast, real cast, and intrinsic cast (image presenting a cast due to a predominant color that must be preserved). We have a database of 700 images which are downloaded from internet or acquired using various digital still cameras. We randomly select 350 images from the database for the neural network learning, and the others are for ...

Sheng-Fuu Lin; Huang-Tsun Chen; Tsung-Han Lin

2011-01-01

210

Solidification and casting  

CERN Document Server

Written by leading experts in their respective fields, Solidification and Casting provides a comprehensive review of topics fundamental to metallurgy and materials science as well as indicates recent trends.From an industrial perspective, the book begins with chapters on the casting techniques most commonly used in industry today. It then describes the underlying science fundamental to solidification mechanisms, including fluid flow, the effects of cooling rates, modern simulation, and modelling methods in use and their application in various casting scenarios. Next, the authors consider the microstructure of cast materials and their defects, and explore how different casting processes can control these parameters. The book concludes with the most recent developments in the field and discusses new processes and materials, such as novel alloys and composites, metallic glasses, ceramics, and superconducting oxides.

Cantor, Brian

2002-01-01

211

Multi-layers castings  

Directory of Open Access Journals (Sweden)

Full Text Available In paper is presented the possibility of making of multi-layers cast steel castings in result of connection of casting and welding coating technologies. First layer was composite surface layer on the basis of Fe-Cr-C alloy, which was put directly in founding process of cast carbon steel 200–450 with use of preparation of mould cavity method. Second layer were padding welds, which were put with use of TIG – Tungsten Inert Gas surfacing by welding technology with filler on Ni matrix, Ni and Co matrix with wolfram carbides WC and on the basis on Fe-Cr-C alloy, which has the same chemical composition with alloy, which was used for making of composite surface layer. Usability for industrial applications of surface layers of castings were estimated by criterion of hardness and abrasive wear resistance of type metal-mineral.

J. Szajnar

2010-01-01

212

Expendable Pattern Casting Technology  

Science.gov (United States)

The expendable pattern casting (EPC) process is a potential casting process breakthrough which could dramatically improve the competitiveness of the U.S. foundry industry. Cooperatively supported by U.S. Industry and the Department of Energy and managed by the American Foundrymen's Society, a project was started in May 1989 to develop and optimize expendable pattern casting technology. Four major tasks were conducted in the first phase of the project. Those tasks involved: (1) reviewing published literature to determine the major problems in the EPC process; (2) evaluating factors influencing sand flow and compaction; (3) evaluating and comparing casting precision obtained in the EPC process with that obtained in other processes; and (4) identifying critical parameters that control dimensional precision and defect formation in EP castings.

1990-07-01

213

Influence of the casting temperature on dental Co-base alloys properties  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The goal of the study is to find the relationship between the value of casting temperature on corrosion resistance, hardness and mechanical properties of two Co-Cr-Mo alloys Remanium 2000+ and Wirobond LFC used in dentistry.Design/methodology/approach: Realized investigations starts from preparing the mould and cast two CoCrMo alloys in 1430, 1440, 1450 and 1460°C. Electrochemical corrosion research were made in water centre which simulated artificial saliva environment, by recording of anodic polarization curves with use the potentiodynamic methods. The compression strength, yield strength and unit shortening was evaluated during the static compression tests on multi-role testing machine MTS. Hardness test were obtained by use the microhardness FM ARS 9000 FUTURE TECH Vickers methods with load 1 kg.Findings: The manufacturing conditions for the Co-Cr-Mo alloys are one of the possible method which effects in increase or decrease of the safety factor in construction. Realized research of the increasing casting temperature about 10-20°C in regard to conditions offered by producer was found that hardness and corrosion resistance change only in small value, while corrosion current of samples casted from 1460°C increase by one order of magnitude to casting from 1430°C. Increase or decrease casting temperature results in decrease the mechanical properties yield strength and compression strength for both alloys.Practical implications: Scientific research of the cobalt alloys used on the dentures confirmed that casting temperature as one of the condition during the manufacturing influence on the most important useful properties like corrosion resistance, strength of the prosthetic constructions and machinability of the CoCrMo alloys.Originality/value: The paper presents an effect of correct selection the casting temperature, on the most important properties of CoCrMo alloys use in dental engineering.

L. Reimann

2013-03-01

214

The spheroidisation of VC carbides in high- vanadium cast iron  

Directory of Open Access Journals (Sweden)

Full Text Available High-vanadium cast iron is a type of white cast iron, in which a regular fibrous ? + VC eutectic with about 20 vol.% of vanadium carbidescrystallises. The paper presents the results of research during which the high-vanadium cast iron was subjected to spheroidisation treatmentwith magnesium Elmag 5800 master alloy. The purpose of this operation was to obtain the VC carbides of a spheroidal shape. The studyalso included metallographic examinations and testing of mechanical properties carried out on high-vanadium cast iron of a eutecticcomposition in as-cast condition and after the spheroidising treatment. The attempt to spheroidise the vanadium carbides has proved to be quite successful. The introduction of magnesium alloy has made nearly one half of the crystallised vanadium carbides acquire a spheroidal shape. The, obtained in this way, high-vanadium cast iron with vanadium carbides of a spheroidal shape showed very high mechanical andplastic properties. The tensile strength Rm increased by 60% compared to the as-cast alloy, while ductility increased more than twenty times. The presented results are based on the initial trials, but further studies of this new material are planned, mainly to check itsresistance to abrasion, to impacts and corrosion. Tests are also planned to increase the fraction of spheroidal carbides and measure theeffect of their content on the mechanical and tribological properties

M. Kawalec

2011-07-01

215

Corrosion resistance of Mg-RE-Zr alloys  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: Magnesium alloys are widely used in the automotive and aerospace industries. Data concerning corrosion of Mg alloys are numerous, but those concerning Mg-RE alloys are scarce. In this paper, the corrosion behavior of cast magnesium alloys containing rare earth elements (WE54, WE43 and Elektron21) were investigated by immersion test in 3.5% NaCl for times up to 7 days.Design/methodology/approach: The study was conducted on WE54, WE43 and Elektron 21 alloys in the as-cast condition. I...

Kie?bus, A.; Michalska, J.; Rzychon?, T.

2007-01-01

216

Point corrosion in steel 17 247  

International Nuclear Information System (INIS)

Susceptibility to point and intergranular corrosion was studied for titanium-stabilized steel CSN 17 247. Specimens were used from two melts featuring different surface finish, placed in three different corrosion media, viz.: 10% iron chloride solution, a solution of copper sulfate, sulfuric acid and distilled water with an addition of copper dust, and a boiling solution of 65% nitric acid. The specimens did not show susceptibility to intergranular corrosion in the sulfuric acid medium. In the boiling nitric acid, the melt with a higher titanium level and a coarser grain showed a lower corrosion rate than that with a lower titanium level, finer grain and the presence of delte-ferrite in the structure. An intensive course of point corrosion was found in the iron chloride medium. As for working, the lowest corrosion rate was found for conventional metal cutting treated surfaces, a higher rate for electrolytically polished surfaces. The highest rate of corrosion was observed for cast grit blasted surfaces. (Z.M.). 3 tabs., 8 refs

217

Corrosion behaviour of solution nitrided stainless steels  

Energy Technology Data Exchange (ETDEWEB)

The case of near net shape parts made from austenitic steel X2CrNiMo17-13-2 and austenitic-ferritic steels X2CrNiMoN22-5-3 (wrought) and G-X3CrNiMoCuN26-6-3-3 (cast) is interstitially enriched with nitrogen by the diffusion-based process ''solution nitriding''. In order to obtain good corrosion resistance and mechanical properties, the solution nitriding parameters and the applied cooling time are selected so, that precipitates are avoided (X2CrNiMo17-13-2, X2CrNiMoN22-5-3). However, in case of a superimposed hydroabrasive load, the presence of nitrides in the case is found to be beneficial. The solution nitrided and the solution annealed conditions of the steels are compared with respect to their susceptibility to corrosion by means of electrochemical polarisation curves. The erosion corrosion behaviour of the materials is analysed in pilot scale flow-loop tests using particle loaded corrosive and particle loaded non-corrosive media. It is shown that ''solution nitriding'' leads to improved corrosion behaviour and/or improved erosion corrosion resistance, in particular in the case of the duplex steels. (orig.)

Berns, H.; Juse, R.L. [Bochum Univ. (Germany); Eul, U.; Heitz, E. [Deutsche Gesellschaft fuer Chemisches Apparatewesen, Chemische Technik und Biotechnologie e.V. (DECHEMA), Frankfurt am Main (Germany)

1999-07-01

218

Corrosion behaviour of solution nitrided stainless steels  

International Nuclear Information System (INIS)

The case of near net shape parts made from austenitic steel X2CrNiMo17-13-2 and austenitic-ferritic steels X2CrNiMoN22-5-3 (wrought) and G-X3CrNiMoCuN26-6-3-3 (cast) is interstitially enriched with nitrogen by the diffusion-based process ''solution nitriding''. In order to obtain good corrosion resistance and mechanical properties, the solution nitriding parameters and the applied cooling time are selected so, that precipitates are avoided (X2CrNiMo17-13-2, X2CrNiMoN22-5-3). However, in case of a superimposed hydroabrasive load, the presence of nitrides in the case is found to be beneficial. The solution nitrided and the solution annealed conditions of the steels are compared with respect to their susceptibility to corrosion by means of electrochemical polarisation curves. The erosion corrosion behaviour of the materials is analysed in pilot scale flow-loop tests using particle loaded corrosive and particle loaded non-corrosive media. It is shown that ''solution nitriding'' leads to improved corrosion behaviour and/or improved erosion corrosion resistance, in particular in the case of the duplex steels. (orig.)

219

Metal Corrosion  

Science.gov (United States)

This learning activity will allow students the opportunity to observe long term corrosion of materials. The instructor will set up several jars or beakers filled with either fresh or salt water, and the class will observe the corrosion of nails, pennies and aluminum foil over time. This activity would be appropriate for grade 4 through college level students. Two weeks should be set aside to observe the results of the experiment. Student, instructor and course evaluation questions are included. This document will serve as a framework for instructors and may be downloaded in PDF format.

Stoebe, Thomas G.

2011-09-22

220

Centrifugal castings of stainless steel spiked with radioactive tracers  

International Nuclear Information System (INIS)

The results of making centrifugal castings of stainless steel spiked with radioactive tracers are presented in this report. After casting, the cylinders were machined and analyses made of the tracer content of the machining chips. The structure of the castings was also investigated for porosity and corrosion resistance. The tests have demonstrated that centrifugal castings can be made from a stainless steel supply contaminated with isotopes of cobalt, strontium, cesium, and iridium. With radiation levels of about 0.4 mR/h [which approaches the Defense Waste Processing Facility (DWPF) upper limit], no smearable surface contamination was obtained from the machined cylinders. For 60 to 67 ?Ci of radioactive isotopes melted with 500 lbs of steel, the contact activity of the ingots was about 0.8 mR/h and the machined cylinders 0.4 mR/h. Most of the original 192Ir and all the 60Co activity was found distributed in the ingots and in the centrifugally cast cylinders. The 60Co was homogeneously distributed and the iridium showed a slight migration due to the centrifugal force field of 120 G's. Porosity and corrosion resistance measurements showed an acceptable structure. 4 refs., 16 figs., 3 tabs

 
 
 
 
221

Container material for the disposal of highly radioactive wastes: corrosion chemistry aspects  

International Nuclear Information System (INIS)

Prior to disposal in crystalline formations it is planned to enclose vitrified highly radioactive waste from nuclear power plants in metallic containers ensuring their isolation from the groundwater for at least 1,000 years. Appropriate metals can be either thermodynamically stable in the repository environment (such as copper), passive materials with very low corrosion rates (titanium, nickel alloys), or metals such as cast iron or unalloyed cast steels which, although they corrode, can be used in sections thick enough to allow for this corrosion. The first part of the report presents the essentials of corrosion science in order to enable even a non-specialist to follow the considerations and arguments necessary to choose the material and design the container against corrosion. Following this, the principles of the long-term extrapolation of corrosion behaviour are discussed. The second part summarizes and comments upon the literature search carried out to identify published results relevant to corrosion in a repository environment. Results of archeaological studies are included wherever possible. Not only the general corrosion behaviour but also localized corrosion and stress corrosion cracking are considered, and the influence of hydrogen on the material behaviour is discussed. Taking the corrosion behaviour as criterion, the author suggests the use either of copper or of cast iron or steel as an appropriate container material. The report concludes with proposals for further studies. (Auth.)

222

The ancient Chinese casting techniques  

Directory of Open Access Journals (Sweden)

Full Text Available In the course of Chinese civilization, which lasted more than 5,000 years, casting production has made a huge contribution. In this paper, some representative metal castings were presented. According to their forming techniques, they can be grouped into stone mould casting, clay mould casting, ablation casting, lost wax casting, stack casting, permanent mould casting, sand casting, etc. According to their materials, they can be categorized into tin bronze, bimetallic bronze, malleable cast iron, ductile cast iron, brass, cupronickel alloy (Packtong, etc. According to their surface decorative techniques they can be devided into gem inlay, gilding, gold and silver inlay, copper inlay, engraved decoration, surface tin-enrichment, mother-of-pearl inlay, burnished works with gold or silver inlay, surface coloring and cloisonné enamel, etc.

Tan Derui

2011-02-01

223

CASTE FRAMEWORK AT NATIONAL LEVEL  

Directory of Open Access Journals (Sweden)

Full Text Available Caste is an important element of the Indian political process. It is legitimate. Caste has been inequality creating in Indian society. Therefore its influence on power shaping & Policy Making process. In this sense caste element has got sphere of influence in political process. Relationship between Caste & politics has been more eminent. Caste has been influencing on politics & politics has been influenced by caste. Limitation of Dominant caste at national level: dominant caste has been demanding for representation on national level. But their demands were not accepted by forward castes. The forward caste has been controlling National level power. Dominant caste has been controlling the state level power.Hinduvat Framework has Successes but Caste Framework has Failure. ST'S Community is not related to Caste Politics. Caste framework is Failure to inclusion of all backward Caste. Caste framework had not successful to decided Social & Economic Public Policy. Because of this caste framework is empty so it has no capacity to competing with other frameworks. It has own Sense of Political Efficacy but on national level it made no impact.

PRAKASH PAWAR

2013-04-01

224

Evaluation on the Corrosion of the Three Ni-Cr Alloys with Different Composition  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Dental casting alloys are widely used in contact with oral tissue for many years now. With the development of new dental alloys over the past 15 years, many questions remain unanswered about their biologic safety. Concepts and current issues concerning the response to the biologic effects of dental casting alloys are presented. In this paper, samples of three commercially available nickel-chrome (Ni-cr) casting alloys (Dentaurum, Bego, Sankin) were taken to assess their corrosion behavior...

Ramesh Chowdhary; Rao, Srinivasa B.

2011-01-01

225

Symptomatic stent cast.  

LENUS (Irish Health Repository)

Biliary stent occlusion is a major complication of endoscopic stent insertion and results in repeat procedures. Various theories as to the etiology have been proposed, the most frequently studied is the attachment of gram negative bacteria within the stent. Several studies have shown prolongation of stent patency with antibiotic prophylaxis. We report the case of stent occlusion from a cast of a previously inserted straight biliary stent; a "stent cast" in an 86-year-old woman with obstructive jaundice. This was retrieved with the lithotrypter and she made an uneventful recovery. This is the first reported case of a biliary stent cast.

Keohane, John

2012-02-03

226

Cast iron zinc galvanizing improved by high temperature oxidation process  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: To evaluate influence of the high-temperature oxidation, as the preliminary stage previous to coating with zinc on the change of surface layer structure as well as subsurface layer of cast iron with flake, vermicular and nodular graphite.Design/methodology/approach: The experiment was led in the temperature range: 850-1050ºC in ambient air. Samples have been taken out from the furnace separately after: 2-12 hours. After scale layer removal the hot dip zinc coating in industrial conditions has carried out. Received effects were compared to these obtained during cast iron coating without preliminary thermal processing. To observation both optical and scanning microscope was applied. Sample’s surface quality was described additionally by roughness measurements.Findings: As the consequence of conducted high-temperature oxidation in subsurface layer of cast iron pores have been created, that in result of coating in liquid zinc were filled with new phase and in this way the new zone with different properties was obtained. Cast iron layer enriched in zinc is considerably thicker than layers got with application of other methods.Research limitations/implications: It is suggested to verify the corrosion resistance of cast iron coated with zinc according to presented method and compare of got results with classic zinc coating effects.Practical implications: The proposed method consisted on combining of hot dip zinc coating of cast iron with previous high temperature oxidation makes possible creation of sub-surface layer with composite character, composed of “after –graphite” voids filled with zinc and metallic matrix, without necessity of pressure processing.Originality/value: New application of high temperature corrosion as the heat treatment improving effects obtained after cast iron zinc coating.

D. J?drzejczyk

2010-11-01

227

Bimetallic layered castings alloy steel – grey cast iron  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast process so-called method of mould cavity preparation.Design/methodology/approach: Prepared bimetallic layered castings consist two fundamental parts i.e. bearing part and working part (layer). The bearing part of bimetallic layered casting is typical foundry material i.e. pearlitic grey cast iron, whereas working part (layer) is depending on accepted variant plat...

Wro?bel, T.

2011-01-01

228

Bainite obtaining in cast iron with carbides castings  

Directory of Open Access Journals (Sweden)

Full Text Available In these paper the possibility of upper and lower bainite obtaining in cast iron with carbides castings are presented. Conditions, when in cast iron with carbides castings during continuous free air cooling austenite transformation to upper bainite or its mixture with lower bainte proceeds, have been given. A mechanism of this transformation has been given, Si, Ni, Mn and Mo distribution in the eutectic cell has been tested and hardness of tested castings has been determined.

S. Pietrowski

2010-01-01

229

Bainite obtaining in cast iron with carbides castings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In these paper the possibility of upper and lower bainite obtaining in cast iron with carbides castings are presented. Conditions, when in cast iron with carbides castings during continuous free air cooling austenite transformation to upper bainite or its mixture with lower bainte proceeds, have been given. A mechanism of this transformation has been given, Si, Ni, Mn and Mo distribution in the eutectic cell has been tested and hardness of tested castings has been determined.

Pietrowski, S.; Gumienny, G.

2010-01-01

230

Adhesion Casting In Low Gravity  

Science.gov (United States)

Adhesion casting in low gravity proposed as technique for making new and improved materials. Advantages of low-gravity adhesion casting, in comparison with adhesion casting in normal Earth gravity, comes from better control over, and greater uniformity of, thicknesses of liquid films that form on and adhere to solid surfaces during casting.

Noever, David A.; Cronise, Raymond J.

1996-01-01

231

Thin Wall Iron Castings; FINAL  

International Nuclear Information System (INIS)

Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified

232

Flow-induced corrosion behavior of absorbable magnesium-based stents.  

Science.gov (United States)

The aim of this work was to study corrosion behavior of magnesium (Mg) alloys (MgZnCa plates and AZ31 stents) under varied fluid flow conditions representative of the vascular environment. Experiments revealed that fluid hydrodynamics, fluid flow velocity and shear stress play essential roles in the corrosion behavior of absorbable magnesium-based stent devices. Flow-induced shear stress (FISS) accelerates the overall corrosion (including localized, uniform, pitting and erosion corrosions) due to the increased mass transfer and mechanical force. FISS increased the average uniform corrosion rate, the localized corrosion coverage ratios and depths and the removal rate of corrosion products inside the corrosion pits. For MgZnCa plates, an increase of FISS results in an increased pitting factor but saturates at an FISS of ?0.15Pa. For AZ31 stents, the volume loss ratio (31%) at 0.056Pa was nearly twice that (17%) at 0Pa before and after corrosion. Flow direction has a significant impact on corrosion behavior as more severe pitting and erosion corrosion was observed on the back ends of the MgZnCa plates, and the corrosion product layer facing the flow direction peeled off from the AZ31 stent struts. This study demonstrates that flow-induced corrosion needs be understood so that Mg-based stents in vascular environments can be effectively designed. PMID:25200844

Wang, Juan; Giridharan, Venkataraman; Shanov, Vesselin; Xu, Zhigang; Collins, Boyce; White, Leon; Jang, Yongseok; Sankar, Jagannathan; Huang, Nan; Yun, Yeoheung

2014-12-01

233

An overview of the corrosion aspect of dental implants (titanium and its alloys)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Titanium and its alloys are used in dentistry for implants because of its unique combination of chemical, physical, and biological properties. They are used in dentistry in cast and wrought form. The long term presence of corrosion reaction products and ongoing corrosion lead to fractures of the alloy-abutment interface, abutment, or implant body. The combination of stress, corrosion, and bacteria contribute to implant failure. This article highlights a review of the various aspects of corros...

Chaturvedi T

2009-01-01

234

Formability of twin roll cast AA5XXX alloy sheet for automotive applications  

Energy Technology Data Exchange (ETDEWEB)

Properties required fo aluminum sheet for automotive applications are high strength, good formability, weldability and corrosion resistance and are met largely by a number of AA5XXX alloys. Twin-roll casting has recently been used to produce low-cost/high-quality AA5XXX aluminum sheet for such applications. Initial results are encouraging and the strip-cast AA5052 and AA5182 alloys are shown to have equivalent or superior mechanical properties and better corrosion resistance with respect to their DC-Cast and Hot Rolled counterparts. While the use of aluminum sheet in automotive structural applications is increasing, better formability to overcome the problems encountered in sheet forming operations has become a critical issue. An attempt was made, in the present work, to characterize the formability of the twin-roll cast AA5XXX alloy sheets further by employing forming limit diagrams and other standard formability assessment tests. (orig.)

Duendar, M.; Akkurt, A.S. [ASSAN Aluminum, Tuzla, Istanbul (Turkey); Birol, Y. [MCTRI, Marmara Research Center, TUBITAK, Gebze, Kocaeli (Turkey)

2002-07-01

235

Method of casting aerogels  

Science.gov (United States)

The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm.sup.3 to 0.6 g/cm.sup.3. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of alcogel which occurs during the drying step of supercritical extraction of solvent.

Poco, John F. (Livermore, CA)

1993-01-01

236

EFFECT OF THE HEAT AND SURFACE LASER TREATMENT ON THE CORROSION DEGRADATION OF THE Mg-Al ALLOYS  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper there is presented the corrosion behavior of the cast magnesium alloys as cast state, after heat and laser treatment. Pitting corrosion resistance of the analyzed alloys was carried out using the potentiodynamic electrochemical method (direct current, based on a anodic polarization curve. On the basis of the achieved anodic polarization curves, using the Tefel extrapolation method near to the corrosion potential, the quantitative data were determined, which describe the electrochemical corrosion process of the investigated alloys: value of the corrosion potential Ecorr (mV, polarization resistance RP (kohm.cm2, corrosion current density icorr (10-6A/cm2, corrosion rate Vcorr (mm/year as well the mass loss Vc (g/m2<.

Leszek A. Dobrza?ski

2011-09-01

237

Corrosion behavior of thixomolded Mg-Al alloys  

Energy Technology Data Exchange (ETDEWEB)

Thixomolding is a new process technology for the high-volume production of magnesium products. This paper describes the corrosion properties of thixomolded Mg-Al alloy specimens in the saline environment. The thixomolded specimen exhibits a higher corrosion resistance compared to die cast ones. The anodic polarization curve in 5wt% NaC1 solution shows a unique passivation-depassivation behavior. The improved heat transfer between the Mg slurry and the die during the injection process produces a fine microstructure and the enrichment of Al content near the surface. The effect of the alloying element on the corrosion performance is also investigated. (author)

Nakatsugawa, I.; Yamada, F.; Takayasu, H.; Tsukeda, T.; Saito, K. [The Japan Steel Works Ltd., Hiroshima (Japan)

1999-07-01

238

Corrosion behavior of thixomolded Mg-Al alloys  

International Nuclear Information System (INIS)

Thixomolding is a new process technology for the high-volume production of magnesium products. This paper describes the corrosion properties of thixomolded Mg-Al alloy specimens in the saline environment. The thixomolded specimen exhibits a higher corrosion resistance compared to die cast ones. The anodic polarization curve in 5wt% NaC1 solution shows a unique passivation-depassivation behavior. The improved heat transfer between the Mg slurry and the die during the injection process produces a fine microstructure and the enrichment of Al content near the surface. The effect of the alloying element on the corrosion performance is also investigated. (author)

239

Corrosion Doctors  

Science.gov (United States)

This site provides a vast amount of general information about various kinds of degradation processes and their impacts on earth systems and human health. It features modules on corrosion effects by natural waters, microbial processes, atmospheric processes, global warming, global dimming (due to particulate matter) and toxic elements. The site also features a recommended reading list, glossary, periodic table of toxic elements, self-administered quizzes, and a long list of related links.

Doctors, Corrosion

240

Corrosion inhibition  

International Nuclear Information System (INIS)

A hydrocarbonaceous liquid stream is modified to contain a minor amount of the amide reaction product of a polyalkylene polyamine and a neo-acid having 5 to 20 carbon atoms, the neo-acid having three alkyl groups on the carbon atom which is in the alpha position relative to the carboxylic group, whereby corrosion of iron and other metals contacted by said stream is significantly reduced

 
 
 
 
241

Fabrication and ageing of cast austenitic steels  

International Nuclear Information System (INIS)

An investigation has been undertaken to determine the magnitude of any reduction in properties which may occur in cast duplex stainless steels and weldments during long term exposure to reactor operating conditions. Test panels were fabricated in CF3 stainless steel by a manual metal arc (MMA) process using 19.9.L (Type 308L) consumables. The mechanical properties and intergranular corrosion resistance of parent material and weldments were measured following accelerated ageing at 3750 and 4000C for up to 10,000 hours. Both the impact energy and J/sub R/ fracture toughness properties of the cast austenitic/ferritic stainless steel were reduced following aging at 4000C for 10,000 hours, whereas austenitic stainless steel MMA weld metals exhibited a reduction in J/sub R/ fracture toughness but no change in impact energy. Even in the unaged state, MMA weld metals were shown to have a much lower resistance to stable crack growth than the parent cast steel, and, following aging, there is a further reduction in the ductile tearing resistance of such weld metals. Therefore, in any assessment of the structural integrity of the reactor coolant pump bowl for a pressurized water reactor (PWR), the weld metal fracture properties during service are likely to be of considerable importance

242

Shadow corrosion  

Science.gov (United States)

An electrochemical mechanism, based on energetically favored complimentary reduction and oxidation reactions, operating in conjunction with radiolysis is proposed for explaining the shadow corrosion phenomenon observed under BWR conditions. The electrochemical reaction on platinum and nickel alloys (Inconel and X-750) is the oxidation of H 2O 2 to produce a localized enhancement in the concentrations of HO 2 and O 2. Energy level of the conduction band of ZrO 2 matches well with that for the reduction of HO 2 and O 2 regenerating H 2O 2. This reduction of the powerful oxidants, stimulates electron emission in ZrO 2 which then is balanced by increased oxidation of zirconium to generate additional electrons and hence also anion vacancies. A coupling between Zircaloy and platinum or nickel alloy is provided by H + transport, the source for initiating shadow corrosion, to Zircaloy-2 (Zircaloy-2 negative relative to platinum or the nickel alloy) in the gap between the materials. An enhanced localized corrosion of Zircaloy-2 occurs, its incidence dependent upon the transport of HO 2, O 2, H + and H 2O 2 in the coolant in the gap.

Ramasubramanian, N.

2004-07-01

243

A new method of producing casts for anatomical studies.  

Science.gov (United States)

The objective of the present study was to verify if polyurethane foam is a suitable material to make accurate casts of vessels and viscera, and to develop a method based on its use for anatomical studies. This new technique has been tested primarily on the lungs of different animals, but also on the renal, intestinal and equine digital vessels. It consisted of three steps: specimen preparation, injection of the foam and corrosion of the cast. All structures injected with foam were properly filled. The bronchial tree and the vessels could be observed up to their finer branches. The method is inexpensive, simple and requires no special equipment. The pre-casting procedure does not require perfusion of the specimens with formalin, or prolonged flushing with carbon dioxide gas or air for drying. The polyurethane foam does not need a catalyst. It is simply diluted with acetone, which does not cause shrinkage of the cast due to evaporation during hardening. The foam naturally expands into the cavities without high pressure of the inoculum, and hardens in just 2 or 3 h at room temperature. Only two drawbacks were observed. The first is the fact that multiple injections cannot be made in the same cavity since the foam solidifies quickly; the second is the slight brittleness of the cast, due to the low elasticity of polyurethane foam. In conclusion, polyurethane foam was a suitable material for producing accurate casts of vessels and viscera. PMID:24788383

De Sordi, Nadia; Bombardi, Cristiano; Chiocchetti, Roberto; Clavenzani, Paolo; Trerè, Claudio; Canova, Marco; Grandis, Annamaria

2014-09-01

244

Sigma phase in the cast alloy based on the FeB3BAl intermetallic phase  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents study results for cast alloy based on the FeB3BAl intermetallic phase. The study material was Fe-28Al-5Cr-1Mo-0,1Zr-0,005B% at. alloy in the cast state. The microscopic research, phase analysis with X-ray diffraction, bending test and observation of thealloy surface exposed to corrosion have been performed. It has been found that presence of the sigma phase in the material structureinfluences high hardness of the tested alloy, its susceptibility to brittle fracture and favours the intercrystalline corrosion.

R. Jasionowski

2011-04-01

245

Quality of the joint between cast steel and cast iron in bimetallic castings  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents conception and production method of skeleton composite castings with use of cast steel G35CrSiMnMoNi skeletoncasting and chromium cast iron EN-GJN-XCr15 filling. Working elements in winning machines and devices, which work in intensiveaberasive wear i.e. liner of exhausters, percussive and ram hammers, are destination of bimetallic castings. Skeleton geometry was basedon three-dimensional symmetrical cubic net consisting of circular connectors and nodes joining 6 connectors according to Cartesian coordinatesystem. Dimension of an elementary cell was equal to 10 mm and diameter of single connector was equal to 5 mm. In rangeof studies were casted cast steel skeletons with chromium cast iron filling and based on metallographic research on light and scanningelectron microscope was made quality assessment of joint in bimetallic castings. Moreover in range of studies was used microanalysisof chemical composition in transition zone of cast steel-cast iron joint.

M. Cholewa

2008-10-01

246

Corrosion of ferrous materials in a basaltic environment  

International Nuclear Information System (INIS)

The results of corrosion tests on A27 cast low-carbon steel are discussed. The corrosion performance of these materials was tested in condensed systems at temperature ranging from 50 C to 200 C and in air-steam mixtures between 150 C and 300 C. The groundwater used was a deoxygenated mild sodium chloride solution. When used, the packing material was 75 percent crushed basalt and 25 percent Wyoming sodium bentonite. In synthetic groundwater corrosion rates for both cast carbon steel and A387 steel in saturated packing and air-steam mixtures were low; maximum rates of 9 ?m/a for A27 steel and 1.8 ?m/a for A387 steel were observed. These maximum rates were observed at intermediate temperatures because of the formation of non-protective corrosion films. In A27 steel magnetite was the principal corrosion product, with non-protective siderite observed at 100 C. Pits were difficult to produce in saturated packing in A27 steel and did not grow. In air-steam mixtures corrosion rates of both steels were again very low, less than 1 ?m/a. Magnetite and small amounts of hematite were detected in corrosion product films

247

Streptococcus mutans attachment on a cast titanium surface  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english This study examined by means of scanning electron microscopy (SEM), the attachment of Streptococcus mutans and the corrosion of cast commercially pure titanium, used in dental dentures. The sample discs were cast in commercially pure titanium using the vacuum-pressure machine (Rematitan System). The [...] surfaces of each metal were ground and polished with sandpaper (#300-4000) and alumina paste (0.3 µm). The roughness of the surface (Ra) was measured using the Surfcorder rugosimeter SE 1700. Four coupons were inserted separately into Falcon tubes contained Mueller Hinton broth inoculated with S. mutans ATCC 25175 (10(9) cuf) and incubated at 37 °C. The culture medium was changed every three days during a 365-day period, after which the falcons were prepared for observations by SEM. The mean Ra value of CP Ti was 0.1527 µm. After S. mutans biofilm removal, pits of corrosion were observed. Despite the low roughness, S. mutans attachment and biofilm formation was observed, which induced a surface corrosion of the cast pure titanium.

Sicknan Soares da, Rocha; Adilson César Abreu, Bernardi; Antônio Carlos, Pizzolitto; Gelson Luis, Adabo; Elisabeth Loshchagin, Pizzolitto.

2009-03-01

248

Development of an Innovative Laser-Assisted Coating Process for Extending Lifetime of Metal Casting Dies. Final Report  

Energy Technology Data Exchange (ETDEWEB)

Die casting dies used in the metal casting industry fail due to thermal fatigue cracking accompanied by the presence of residual tensile stresses, corrosion, erosion and wear of die surfaces. This phase 1 SBIR Final Report summarize Karta Technologies research involving the development of an innovative laser coating technology for metal casting dies. The process involves depositing complex protective coatings of nanocrystalline powders of TiC followed by a laser shot peening. The results indicate a significant improvement in corrosion and erosion resistance in molten aluminum for H13 die casting die steels. The laser-coated samples also showed improved surface finish, a homogeneous and uniform coating mircrostructure. The technology developed in this research can have a significant impact on the casting industry by saving the material costs involved in replacing dies, reducing downtime and improving the quality.

Madhav Rao Gonvindaraju

1999-10-18

249

Corrosion of stainless steels  

International Nuclear Information System (INIS)

The paper starts by describing the alloy components of stainless steels and then proceeds to discuss the corrosion processes. The chromium depletion theory, pitting, stress crack corrosion, intercrystalline corrosion, intercrystalline fatigue crack corrosion, corrosion due to deformation, and corrosion due to the formation of Evans' elements are discussed. Further sections deal with the brazing und welding of stainless steels and with the test solutions used. (orig./IHOE)

250

Corrosion behavior of carbon steels under tuff repository environmental conditions  

International Nuclear Information System (INIS)

Carbon steels may be used for borehole liners in a potential high-level nuclear waste repository in tuff in Nevada. Borehole liners are needed to facilitate emplacement of the waste packages and to facilitate retrieval of the packages, if required. Corrosion rates of low carbon structural steels AISI 1020 and ASTM A-36 were determined in J-13 well water and in saturated steam at 1000C. Tests were conducted in air-sparged J-13 water to attain more oxidizing conditions representative of irradiated aqueous environments. A limited number of irradiation corrosion and stress corrosion tests were performed. Chromium-molybdenum alloy steels and cast irons were also tested. These materials showed lower general corrosion but were susceptible to stress corrosion cracking when welded. 4 references, 4 tables

251

Corrosion behavior of carbon steels under tuff repository environmental conditions  

International Nuclear Information System (INIS)

Carbon steels may be used for borehole liners in a potential high-level nuclear waste repository in tuff in Nevada. Borehole liners are needed to facilitate emplacement of the waste packages and to facilitate retrieval of the packages, if required. Corrosion rates of low carbon structural steels AISI 1020 and ASTM A-36 were determined in J-13 well water and in saturated steam at 1000C. J-13 well water is representative of water which has percolated through the tuff horizon where the repository would be located. Tests were conducted in air-sparged J-13 water to attain stronger oxidizing conditions. a limited number of irradiation corrosion and stress corrosion tests were performed. Chromium-molybdenum alloy steels and cast irons were also tested. These materials showed lower general corrosion but were susceptible to stress corrosion cracking when welded. 4 refs., 7 tabs

252

Corrosion/94 conference papers  

International Nuclear Information System (INIS)

The approximately 500 papers from this conference are divided into the following sections: Rail transit systems--stray current corrosion problems and control; Total quality in the coatings industry; Deterioration mechanisms of alloys at high temperatures--prevention and remediation; Research needs and new developments in oxygen scavengers; Computers in corrosion control--knowledge based system; Corrosion and corrosivity sensors; Corrosion and corrosion control of steel reinforced concrete structures; Microbiologically influenced corrosion; Practical applications in mitigating CO2 corrosion; Mineral scale deposit control in oilfield-related operations; Corrosion of materials in nuclear systems; Testing nonmetallics for life prediction; Refinery industry corrosion; Underground corrosion control; Mechanisms and applications of deposit and scale control additives; Corrosion in power transmission and distribution systems; Corrosion inhibitor testing and field application in oil and gas systems; Decontamination technology; Ozone in cooling water applications, testing, and mechanisms; Corrosion of water and sewage treatment, collection, and distribution systems; Environmental cracking of materials; Metallurgy of oil and gas field equipment; Corrosion measurement technology; Duplex stainless steels in the chemical process industries; Corrosion in the pulp and paper industry; Advances in cooling water treatment; Marine corrosion; Performance of materials in environmsion; Performance of materials in environments applicable to fossil energy systems; Environmental degradation of and methods of protection for military and aerospace materials; Rail equipment corrosion; Cathodic protection in natural waters; Characterization of air pollution control system environments; and Deposit-related problems in industrial boilers. Papers have been processed separately for inclusion on the data base

253

Three-dimensional registration of synchrotron radiation-based micro-computed tomography images with advanced laboratory micro-computed tomography data from murine kidney casts  

Science.gov (United States)

Malfunction of oxygen regulation in kidney and liver may lead to the pathogenesis of chronic diseases. The underlying mechanisms are poorly understood. In kidney, it is hypothesized that renal gas shunting from arteries to veins eliminates excess oxygen. Such shunting is highly dependent on the structure of the renal vascular network. The vascular tree has so far not been quantified under maintenance of its connectivity as three-dimensional imaging of the vessel tree down to the smallest capillaries, which in mouse model are smaller than 5 ?m in diameter, is a challenging task. An established protocol uses corrosion casts and applies synchrotron radiation-based micro-computed tomography (SR?CT), which provides the desired spatial resolution with the necessary contrast. However, SR?CT is expensive and beamtime access is limited. We show here that measurements with a phoenix nanotomrm (General Electric, Wunstorf, Germany) can provide comparable results to those obtained with SR?CT, except for regions with small vessel structures, where the signal-to-noise level was significantly reduced. For this purpose the nanotom®m measurement was compared with its corresponding measurement acquired at the beamline P05 at PETRA III at DESY, Hamburg, Germany.

Thalmann, Peter; Hieber, Simone E.; Schulz, Georg; Deyhle, Hans; Khimchenko, Anna; Kurtcuoglu, Vartan; Olgac, Ufuk; Marmaras, Anastasios; Kuo, Willy; Meyer, Eric P.; Beckmann, Felix; Herzen, Julia; Ehrbar, Stefanie; Müller, Bert

2014-09-01

254

Anodization of cast aluminium alloys produced by different casting methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper the usability of two casting methods, of sand and high pressure cast for the anodization of AlSi12 and AlSi9Cu3 aluminium cast alloys was investigated. With defined anodization parameters like electrolyte composition and temperature, current type and value a anodic alumina surface layer was produced. The quality, size and properties of the anodic layer was investigated after the anodization of the chosen aluminium cast alloys. The Alumina layer was observed used light microscope...

Labisz, K.; Dobrzan?ski, L. A.; Konieczny, J.

2008-01-01

255

Continuous roll casting of aluminium alloys – casting parameters analysis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The main goal of the paper was to present the influence of casting parameters on casting conditions and interference of casting parameters on the final strip characteristics such as constant strip thickness, surface quality and roughness of aluminum alloys sheet 6,30 to 6,50 mm thick. The study shows that casting speed, roll force and roll gap should have the greatest influence on the final strip thickness, and that the examined parameters agree well with the theoretical standpoints.

Krstic? Vukelja, E.; Duplanc?ic?, I.; Lela, B.

2010-01-01

256

Casting Characteristics of Aluminum Die Casting Alloys  

Energy Technology Data Exchange (ETDEWEB)

The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

Makhlouf M. Makhlouf; Diran Apelian

2002-02-05

257

Effects of Cr - Ni 18/9 Austenitic Cast Steel Modification by Mischmetal  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the results of Cr - Ni 18/9 austenitic cast steel modifications by mischmetal. The study was conducted on industrial melts. Cast steel was melted in an electric induction furnace with a capacity of 2000 kg and a basic lining crucible. .The mischmetal was introduced into the ladle during tapping of the cast steel from the furnace. The effectiveness of modification was examined with the carbon content of 0.1% and the presence of ? ferrite in the structure of cast steel stabilized with titanium. The changes in the structure of cast steel and their effect on mechanical properties and intergranular corrosion were studied. It was found that rare earth metals decrease the sulfurcontent in cast steel and above all, they cause a distinct change in morphology of the ? ferrite and non-metallic inclusions. These changes have improved mechanical properties. R02, Rm, and A5 and toughness increased significantly. There was a great increase of the resistance to intergranular corrosion in the Huey test. The study confirmed the high efficiency of cast steel modification by mischmetal in industrial environments. The final effect of modification depends on the form and manner of placing mischmetal into the liquid metal and the melting technology, ie the degree of deoxidation and desulfurization of the metal in the furnace.

M. Gajewski

2012-12-01

258

Characterization of Al-Mn particles in AZ91D investment castings  

International Nuclear Information System (INIS)

Manganese is currently added to Mg-Al alloys in order to improve the corrosion behavior of cast components. A part of this manganese is dissolved in the magnesium matrix and the balance is found as fine Al(Mn,Fe) particles dispersed within castings. For AZ91D specimens prepared using the plaster mould investment casting process, these particles were observed in very large quantity at the surface of castings. These particles were characterized by scanning electron microscopy and electron probe microanalysis. It was found that they consist of Al8Mn5 phase and that their morphology and size depend on local solidification conditions. Their presence at the surface of the castings is related to low solidification rates and reduced thermal gradients at the mould/metal interface

259

Corrosion/95 conference papers  

International Nuclear Information System (INIS)

The papers in this conference represent the latest technological advances in corrosion control and prevention. The following subject areas are covered: cathodic protection in natural waters; materials for fossil fuel combustion and conversion systems; modern problems in atmospheric corrosion; innovative ideas for controlling the decaying infrastructure; deposits and their effects on corrosion in industry; volatile high temperature and non aqueous corrosion inhibitors; corrosion of light-weight and precoated metals for automotive application; refining industry corrosion; corrosion in pulp and paper industry; arctic/cold weather corrosion; materials selection for waste incinerators and associated equipment; corrosion measurement technology; environmental cracking of materials; advancing technology in the coating industry; corrosion in gas treating; green inhibition; recent advances in corrosion control of rail equipment; velocity effects and erosion corrosion in oil and gas production; marine corrosion; corrosion of materials in nuclear systems; underground corrosion control; corrosion in potable and industrial water systems in buildings and its impact on environmental compliance; deposit related boiler tube failures; boiler systems monitoring and control; recent developments and experiences in reactive metals; microbiologically influenced corrosion; corrosion and corrosion control for steel reinforced concrete; international symposium on the use of 12 and 13 Cr stainlemposium on the use of 12 and 13 Cr stainless steels in oil and gas production environments; subsea corrosion /erosion monitoring in production facilities; fiberglass reinforced pipe and tubulars in oilfield service; corrosion control technology in power transmission and distribution; mechanisms and methods of scale and deposit control; closing the loop -- results oriented cooling system monitoring and control; and minimization of aqueous discharge

260

Effect of heat treatment on corrosion resistance of WE54 alloy  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: Poor corrosion resistance is one of the main causes to prevent magnesium alloys for wide applications.The addition of rare earth elements (RE is an effective way to improve corrosion resistance of magnesiumalloys. Heat treatment condition can also influence the corrosion behavior of magnesium alloys. The purpose ofthe investigation was to study the corrosion resistance of WE54 alloy after heat treatment.Design/methodology/approach: The study was conducted on WE54 alloy in the as-cast condition and after heattreatment at 250-300?C for periods of time 4 – 96 h. Immersion test was performed using not deaerated 3.5%NaCl solution at room temperature. Specimens were placed in 3.5% NaCl solution for periods of time betweenone and 7 days. The dissolution rates (mg cm-2 day-1 were determined by weight loss measurements. Afterimmersion test, the microstructure and the appearances of the corroded structure were examined by scanningelectron microscopy.Findings: The corrosion rate of WE54 alloy strongly depends on heat treatment condition. WE54 alloy in theas-cast and after solution treated have similar corrosion behavior, different from that of aged specimens. Thecurves of corrosion rate for aged specimens were higher than that for as-cast and solution treated conditions. Itwas also noticed that the longer time of ageing the higher corrosion rates were observed.Research limitations/implications: The knowledge about corrosion behavior of Mg-RE-Zr alloys is currentlyunder evaluation on many speciality applications where lightweight connected with optimum corrosionresistance are required.Practical implications: The knowledge about corrosion behavior of Mg-RE-Zr alloys is currently underevaluation on many speciality applications where lightweight connected with optimum corrosion resistance arerequired.Originality/value: This paper includes the effect of heat treatment condition on corrosion resistance of WE54magnesium alloy.

T. Rzycho?

2007-01-01

 
 
 
 
261

Bulk metallic glass tube casting  

International Nuclear Information System (INIS)

Research highlights: ? Tubular specimens of Zr55Cu30Al10Ni5 cast in custom arc-melting furnace. ? Tilt casting supplemented by suction casting. ? Bulk metallic glass formed only with optimized processing parameters. ? Fully amorphous tubes with 1.8 mm wall thickness and 25 mm diameter. - Abstract: Tubular bulk metallic glass specimens were produced, using a custom-built combined arc-melting tilt-casting furnace. Zr55Cu30Al10Ni5 tubes with outer diameter of 25 mm and 0.8-3 mm wall thicknesses were cast, with both tilt and suction casting to ensure mold filling. Tilt casting was found to fill one side of the tube mold first, with the rest of the tube circumference filled subsequently by suction casting. Optimized casting parameters were required to fully fill the mold and ensure glass formation. Too small melt mass and too low arc power filled the mold only partially. However, too large melt mass and higher arc power which lead to the best mold filling also lead to partial crystallization. Variations in processing parameters were explored, until a glassy ring with 1.8 mm thickness was produced. Different sections of the as-cast ring were investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and instrumented indentation to ensure amorphous microstructure. Atomic force microscopy (AFM) was used to compare the surface qualities of the first- and last-filled sections. These measurements confirmed the glassy structure of the cast ring, andsy structure of the cast ring, and that, the tilt cast tube section consistently showed better surface quality than the suction cast section. Optimized casting parameters are required to fully realize the potential of directly manufacturing complex shapes out of high-purity bulk metallic glasses by tilt casting.

262

The Influence of Corrosion on the Microstructure of Thermally Treated ZA27/SiCp Composites  

Directory of Open Access Journals (Sweden)

Full Text Available The influence of corrosion on the microstructure of ZA27/SiCp composites was examined. The composites were produced by compo casting technique and then subjected to the thermal treatment (T4 regime. Microstructural examinations were performed after 30-day exposure of thermally treated composites in the sodium-chloride solution. Corrosion processes have occurred in the composite matrix. Corrosion did not affect SiC particles in the composites. The local progress of corrosion in depth of the composite matrix was noticed in micro-cracks. Corrosion resistance of ZA27/SiCp composites was evaluated based on the mass loss of composite samples during the immersion test. It was found that corrosion resistance of the composites decreased with increase in content of SiC particles. The applied thermal treatment had a negative influence on the corrosion resistance of ZA27/SiCp composites.

B. Bobi?

2014-03-01

263

Scheduled Caste Women: Problems And Challenges  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper analyzed the Caste system based on Varnas during the ancient India. It also examined the demerits of caste attached to the present scheduled castes in general and scheduled caste women in particular. The scheduled caste women are disadvantaged by their caste and gender and as such they are subject to exploitation and discrimination by their family members, by their caste people and by forward castes. Hence, there is increase in exploitation, discrimination and violence against the s...

Vijayakumar Murthy; Jaikishan Thakur

2013-01-01

264

Grain boundary corrosion of copper canister material  

International Nuclear Information System (INIS)

The proposed design for a final repository for spent fuel and other long-lived residues in Sweden is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will then be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast inner container fitted inside a corrosion-resistant copper canister. During fabrication of the outer copper canisters there will be some unavoidable grain growth in the welded areas. As grains grow they will tend to concentrate impurities within the copper at the new grain boundaries. The work described in this report was undertaken to determine whether there is any possibility of enhanced corrosion at grain boundaries within the copper canister. The potential for grain boundary corrosion was investigated by exposing copper specimens, which had undergone different heat treatments and hence had different grain sizes, to aerated artificial bentonite-equilibrated groundwater with two concentrations of chloride, for increasing periods of time. The degree of grain boundary corrosion was determined by atomic force microscopy (AFM) and optical microscopy. AFM showed no increase in grain boundary 'ditching' for low chloride groundwater. In high chloride groundwater the surface was covered uniformly with a fine-grained oxide. No increases in oxide thickness were observed. No significant grain boundary attack was observed using optical microscopy either. The work suggests that in aerated artificial groundwaters containing chloride ions, grain boundary corrosion of copper is unlikely to adversely affect SKB's copper canisters

265

Mix/Cast Contamination Control  

Science.gov (United States)

Presented is a training handbook for Mix/Cast Contamination Control; a part of a series of training courses to qualify access to Mix/Cast facilities. Contents: List Contamination Control Requirements; Identify foreign objects debris (FOD), Control Areas and their guidelines; Describe environmental monitoring; List Contamination Control Initiatives; Describe concern for Controlled Materials; Identify FOD Controlled Areas in Mix/Cast.

Wallentine, M.

2005-01-01

266

Wear resistance of cast iron  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper investigations of abrasive and adhesive wear resistance of different cast iron grades have been presented. Examinations showed, that the most advantageous pair of materials is the cast iron – the hardened steel with low-tempered martensite. It was found, that martensitic nodular cast iron with carbides is the most resistant material.

Pietrowski, S.; Gumienny, G.

2008-01-01

267

Bimetallic layered castings alloy steel – carbon cast steel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast processso-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer). The bearing part of bimetallic layered casting is typical foundry material i.e. ferritic-pearlitic carbon cast steel, whereas working part (layer) is plate of austenitic alloy steel sort X10CrNi 18-8. The ratio of thickness betwe...

Wro?bel, T.; Cholewa, M.; Tenerowicz, S.

2011-01-01

268

Society for Vascular Medicine  

Science.gov (United States)

... Learn more! Updated! Patient Information Pages from Vascular Medicine December 2014 Carotid artery disease More info for ... Learn more. Trending Now: Hot Topics in Vascular Medicine Video Series! Fibromuscular Dysplasia (FMD) with Drs. Jeffrey ...

269

Effect of inoculation on microstructure, mechanical and corrosion properties of high manganese ductile Ni-resist alloy  

International Nuclear Information System (INIS)

Highlights: • Experimental purpose of mechanical properties of modified ductile Ni-resist. • Evaluation of the influence of high manganese content on mechanical properties and corrosion behaviour. • Metallurgical, phases analysis and microstructural parameters determination. - Abstract: The performance of modified ductile Ni-resist (DNR) adapted with higher manganese content, may be improved by inoculation in order that it may be of use in corrosive and high temperature application. In this study, DNR cast alloy was casting to different manganese content before undergoing inoculation process with various inoculation percentages. Scanning Electron Microscope/Energy Dispersive X-ray Spectroscopy SEM/EDS characterized the corrosion products. The results showed that increasing inoculation did decreased carbide formation led to improved tensile value and decreased hardness value. Moreover, inoculation led to uniform distribution of graphite resulted in lower corrosion rates. It can be concluded that inoculation process improved the mechanical properties of the alloy and satisfy the corrosion resistance criteria required for corrosive environment

270

Pipe Lines – External Corrosion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two areas of corrosion occur in pipe lines: corrosion from the medium carried inside the pipes; corrosion attack upon the outside of the pipes (underground corrosion. Electrolytic processes are also involved in underground corrosion. Here the moisture content of the soil acts as an electrolyte, and the ions required to conduct the current are supplied by water-soluble salts (chlorides, sulfates, etc.) present in the soil. The nature and amount of these soluble materials can vary within a wide...

Dan Babor

2008-01-01

271

Corrosion resistance of Mg-RE-Zr alloys  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: Magnesium alloys are widely used in the automotive and aerospace industries. Data concerning corrosion of Mg alloys are numerous, but those concerning Mg-RE alloys are scarce. In this paper, the corrosion behavior of cast magnesium alloys containing rare earth elements (WE54, WE43 and Elektron21 were investigated by immersion test in 3.5% NaCl for times up to 7 days.Design/methodology/approach: The study was conducted on WE54, WE43 and Elektron 21 alloys in the as-cast condition. Immersion test was performed using not deaerated 3.5% NaCl solution at room temperature. Several specimens were placed in 3.5% NaCl solution for periods of time between one and 7 days. The dissolution rates (mg/cm-2day-1 were determined by weight loss measurements.Findings: Elektron 21 alloy exhibits the highest corrosion rate during the immersion test, while WE54 and WE43 alloys had a similar corrosion behavior. The corrosion rates of WE54 and Elektron 21 alloys incresed lineally with increasing the exposure time in 3.5% NaCl, and that of WE43 was almost unchanged and finally reached maximum value 0.26 mg/cm-2day-1.Research limitations/implications: The knowledge about corrosion behavior of Mg-RE-Zr alloys is currently under evaluation on many speciality applications where lightweight connected with optimum corrosion resistance are requiredPractical implications: The comparative results of corrosion behavior of new Mg-RE-Zr alloys leads to optimum choice of alloy for application in automotive, aircraft and aerospace industries.Originality/value: This paper includes the comparative results of corrosion resistance investigations of new Mg-RE–Zr alloys.

A. Kie?bus

2007-03-01

272

An overview of the corrosion aspect of dental implants (titanium and its alloys  

Directory of Open Access Journals (Sweden)

Full Text Available Titanium and its alloys are used in dentistry for implants because of its unique combination of chemical, physical, and biological properties. They are used in dentistry in cast and wrought form. The long term presence of corrosion reaction products and ongoing corrosion lead to fractures of the alloy-abutment interface, abutment, or implant body. The combination of stress, corrosion, and bacteria contribute to implant failure. This article highlights a review of the various aspects of corrosion and biocompatibility of dental titanium implants as well as suprastructures. This knowledge will also be helpful in exploring possible research strategies for probing the biological properties of materials.

Chaturvedi T

2009-01-01

273

Control of cast iron and casts manufacturing by Inmold method  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper the usability of cast iron spheroidizing process in mould control by ATD method as well as by ultrasonic method were presented. Structure of instrumentation needed for control form performance of cast iron spheroidizing by Inmold method was illustrated. Author, pointed out that amount of magnesium master alloy should obtain 0,8 ÷ 1,0% of mass in form at all. Such quantity of preliminary alloy assure of obtain of nodular graphite in cast iron. In consequence of this, is reduce the cast iron liquidus temperature and decrease of recalescence temperature of graphite-eutectic crystallization in compare with initial cast iron. Control of casts can be carried out by ultrasonic method. In plain cast iron, ferritic-pearlitic microstructure is obtaining. Additives of 1,5% Cu ensure pearlitic structure.

S. Pietrowski

2009-07-01

274

Thermal aging of cast duplex stainless steels  

International Nuclear Information System (INIS)

Cast duplex stainless steels of CR8M and CF8 are used in major components because of their superior characteristics, such as corrosion resistance, weldability and so on. But, these stainless steels are known to have tendency of thermal aging embrittlement after long term service. Therefore, mechanical properties have been investigated using Charpy impact specimens and fracture toughness specimens aged at 300?400 C up to 40,000 hours. As the results, effects of thermal aging on mechanical properties of these stainless steels were identified and a good relationship between Charpy impact energy and fracture toughness was obtained. In addition, prediction method for Charpy absorbed energy and fracture toughness was established

275

Quality of the joint between cast steel and cast iron in bimetallic castings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper presents conception and production method of skeleton composite castings with use of cast steel G35CrSiMnMoNi skeletoncasting and chromium cast iron EN-GJN-XCr15 filling. Working elements in winning machines and devices, which work in intensiveaberasive wear i.e. liner of exhausters, percussive and ram hammers, are destination of bimetallic castings. Skeleton geometry was basedon three-dimensional symmetrical cubic net consisting of circular connectors and nodes joining 6 connectors...

Cholewa, M.; Tenerowicz, S.; Wro?bel, T.

2008-01-01

276

Automatic inspection of surface defects in die castings after machining  

Directory of Open Access Journals (Sweden)

Full Text Available A new camera based machine vision system for the automatic inspection of surface defects in aluminum die casting was developed by the authors. The problem of surface defects in aluminum die casting is widespread throughout the foundry industry and their detection is of paramount importance in maintaining product quality. The casting surfaces are the most highly loaded regions of materials and components. Mechanical and thermal loads as well as corrosion or irradiation attacks are directed primarily at the surface of the castings. Depending on part design and processing techniques, castings may develop surface discontinuities such as cracks or tears, inclusions due to chemical reactions or foreign material in the molten metal, and pores that greatly influence the material ability to withstand these loads. Surface defects may act as a stress concentrator initiating a fracture point. If a pressure is applied in this area, the casting can fracture. The human visual system is well adapted to perform in areas of variety and change; the visual inspection processes, on the other hand, require observing the same type of image repeatedly to detect anomalies. Slow, expensive, erratic inspection usually is the result. Computer based visual inspection provides a viable alternative to human inspectors. Developed by authors machine vision system uses an image processing algorithm based on modified Laplacian of Gaussian edge detection method to detect defects with different sizes and shapes. The defect inspection algorithm consists of three parameters. One is a parameter of defects sensitivity, the second parameter is a threshold level and the third parameter is to identify the detected defects size and shape. The machine vision system has been successfully tested for the different types of defects on the surface of castings.

S. J. ?wi??o

2011-07-01

277

Corrosion/96 conference papers  

International Nuclear Information System (INIS)

Topics covered by this conference include: cathodic protection in natural waters; cleaning and repassivation of building HVAC systems; worldwide opportunities in flue gas desulfurization; advancements in materials technology for use in oil and gas service; fossil fuel combustion and conversion; technology of corrosion inhibitors; computers in corrosion control--modeling and information processing; recent experiences and advances of austenitic alloys; managing corrosion with plastics; corrosion measurement technology; corrosion inhibitors for concrete; refining industry; advances in corrosion control for rail and tank trailer equipment; CO2 corrosion--mechanisms and control; microbiologically influenced corrosion; corrosion in nuclear systems; role of corrosion in boiler failures; effects of water reuse on monitoring and control technology in cooling water applications; methods and mechanisms of scale and deposit control; corrosion detection in petroleum production lines; underground corrosion control; environmental cracking--relating laboratory results and field behavior; corrosion control in reinforced concrete structures; corrosion and its control in aerospace and military hardware; injection and process addition facilities; progress reports on the results of reinspection of deaerators inspected or repaired per RP0590 criteria; near 100% volume solids coating technology and application methods; materials performance in high temperature environments contaice in high temperature environments containing halides; impact of toxicity studies on use of corrosion/scale inhibitors; mineral scale deposit control in oilfield related operations; corrosion in gas treating; marine corrosion; cold climate corrosion; corrosion in the pulp and paper industry; gaseous chlorine alternatives in cooling water systems; practical applications of ozone in recirculating cooling water systems; and water reuse in industry. Over 400 papers from this conference have been processed separately for inclusion on the data base

278

The anaerobic corrosion of carbon steel in concrete  

International Nuclear Information System (INIS)

The report describes the work of a two year programme investigating the anaerobic corrosion of carbon steel embedded in a range of candidate repository cements and concretes at laboratory temperatures. The factors investigated in the study were the rate of the anaerobic corrosion reaction, the effect of hydrogen overpressure on the reaction rate and the form of the corrosion product. Both electrochemical and sample weight loss corrosion rate measurements were used. The cements and concretes used were prepared both with and without small additions of chloride (2% by weight of mix water). The results indicate that the corrosion rate is low, < 1 ?m/year, the effect of hydrogen overpressure is not significant over the range of pressures investigated, 1-100 atmospheres, and that the corrosion product is dependent on the cement used to cast the samples. Magnetite was identified in the case of blast furnace slag replacement cements but for pulverised fuel ash and ordinary Portland cements no corrosion product was evident either from X-ray diffraction or laser Raman measurements. Further work is presently underway to investigate the effects of elevated temperatures and chloride levels on the anaerobic corrosion reaction and the rate of hydrogen gas production. (author)

279

Color Casts Detection and Adjustment  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a new method for detection and adjustment color cast. Using the neural network to detect color cast and classify images into three subsets: no cast, real cast, and intrinsic cast (image presenting a cast due to a predominant color that must be preserved. We have a database of 700 images which are downloaded from internet or acquired using various digital still cameras. We randomly select 350 images from the database for the neural network learning, and the others are for testing. From each training image, we can calculate 13 statistical parameters as input to the neural network. The second part is the white balance algorithm which is applied to the image while a real cast is found by the color cast detector. The test image is divided into m blocks. For each block, the output weighting can be obtained by a fuzzy system and the luminance weighted value is also calculated. Finally, we can obtain the new amplifier gains of the R, G, and B channel to adjust the color cast. If the input image be classified as no cast or intrinsic cast, white balance algorithm is not applied.

Sheng-Fuu Lin

2011-07-01

280

Cast iron - a predictable material  

Directory of Open Access Journals (Sweden)

Full Text Available High strength compacted graphite iron (CGI or alloyed cast iron components are substituting previously used non-ferrous castings in automotive power train applications. The mechanical engineering industry has recognized the value in substituting forged or welded structures with stiff and light-weight cast iron castings. New products such as wind turbines have opened new markets for an entire suite of highly reliable ductile iron cast components. During the last 20 years, casting process simulation has developed from predicting hot spots and solidification to an integral assessment tool for foundries for the entire manufacturing route of castings. The support of the feeding related layout of the casting is still one of the most important duties for casting process simulation. Depending on the alloy poured, different feeding behaviors and self-feeding capabilities need to be considered to provide a defect free casting. Therefore, it is not enough to base the prediction of shrinkage defects solely on hot spots derived from temperature fields. To be able to quantitatively predict these defects, solidification simulation had to be combined with density and mass transport calculations, in order to evaluate the impact of the solidification morphology on the feeding behavior as well as to consider alloy dependent feeding ranges. For cast iron foundries, the use of casting process simulation has become an important instrument to predict the robustness and reliability of their processes, especially since the influence of alloying elements, melting practice and metallurgy need to be considered to quantify the special shrinkage and solidification behavior of cast iron. This allows the prediction of local structures, phases and ultimately the local mechanical properties of cast irons, to asses casting quality in the foundry but also to make use of this quantitative information during design of the casting. Casting quality issues related to thermally driven stresses in castings are also gaining increasing attention. State-of-the-art tools allow the prediction of residual stresses and iron casting distortion quantitatively. Cracks in castings can be assessed, as well as the reduction of casting stresses during heat treatment. As the property requirements for cast iron as a material in design strongly increase, new alloys and materials such as ADI might become more attractive, where latest software developments allow the modeling of the required heat treatment. Phases can be predicted and parametric studies can be performed to optimize the alloy dependent heat treatment conditions during austenitization, quenching and ausferritization. All this quantitative information about the material's performance is most valuable if it can be used during casting design. The transfer of local properties into the designer? world, to predict fatigue and durability as a function of the entire manufacturing route, will increase the trust in this old but highly innovative material and will open new opportunities for cast iron in the future. The paper will give an overview on current capabilities to quantitatively predict cast iron specific defects and casting performance and will highlight latest developments in modeling the manufacture of cast iron and ADI as well as the prediction of iron casting stresses.

Jorg C. Sturm

2011-02-01

 
 
 
 
281

The mechanism of the end grain corrosion of stainless steel in nitric acid solutions and its prevention  

International Nuclear Information System (INIS)

Austenitic stainless steels with low carbon content have good corrosion resistance in nitric acid solutions. However, these steels are susceptible to corrosion in nitric acid solutions which contain highly oxidizing ions such as Cr2O72-, Run+ etc. One of these is called 'End Grain Corrosion' or 'Tunnelling Corrosion'. In this type of corrosion, a part of the cross-section of plate is preferentially attacked severely. In this study, it was clarified that the end grain corrosion was caused by intergranular corrosion (IGC) at phosphorus segregated areas which were induced during casting. And it was also found that the decrease of P content less than 0.015%, and heat treatments to reduce segregation of P were very effective to prevent the end grain corrosion. (author)

282

Study on the effect of corrosion on the tensile behavior of an AZ91 alloy  

Energy Technology Data Exchange (ETDEWEB)

The effect of corrosion on the tensile behavior of an as-cast AZ91 alloy was investigated via systematical experiments. The corrosion residual strength of the AZ91 magnesium alloy is approximately negative linear dependent on the extreme depth of corrosion pit, which was quantitatively obtained by the corrosion morphology analysis and the statistic analysis. Experimental results reveal that the corrosion residual strength of the AZ91 magnesium alloy dropped quickly in the first 40 h due to the initiation and development of the corrosion pit and subsequently decreased slowly as a result of the development of the corrosion pit encountered the {beta} phase. The {beta} phase at the grain boundary of the primary {alpha} phase acts as an effective barrier to prevent the development of the corrosion pit into the alloy matrix and thus remarkably prevents the drop of the corrosion residual strength. In general, the variation of the corrosion residual strength exhibits an exponential decay regulation within the testing time. Consequently, the empirical prediction of the corrosion residual strength was given with regard to the variation of the corrosion residual strength varied with the immersion time. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Wang, Q.; Liu, Y.H.; Zhang, L.N.; Song, Y.L.; Zhang, D.W.; Li, C.F. [Key Laboratory of Automobile Materials, Ministry of Education, College of Materials Science and Engineering, Jilin University, Changchun (China)

2010-03-15

283

Effect of Al additions and heat treatment on corrosion properties of Mg-Al based alloys  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: In this paper there is presented the corrosion behavior of cast magnesium alloys in as cast state and after heat treatment.Design/methodology/approach: The following results concern scanning electron microscopy investigations in the SE as well BSE observation mode, for better phase contrast results, also qualitative microanalysis was applied for chemical composition investigations of the surface. Pitting corrosion resistance was carried out using the potentiodynamic electrochemical method (direct current, based on anodic polarisation curve. Based on the achieved anodic polarisation curves, using the Tefel extrapolation method near to the corrosion potential, the quantitative data were determined, which describe the electrochemical corrosion process of the investigated alloys: value of the corrosion potential Ecor (mV, polarisation resistance Rp (k?/cm2, corrosion current density icor (?A/cm2, corrosion rate Vp (mm/year as well the mass loss Vc (g/m2.Findings: Surface morphology of the samples after corrosion test performed after and before heat treatment show irregular shaped pinholes and numerous cracks on the material surface layer.Research limitations/implications: The applied cooling rate and alloy additions seems to be a good compromise for properties and microstructures, nevertheless further tests should be carried out in order to examine different cooling rates and parameters of solution treatment process and aging process.Practical implications: Investigation results concerning the surface layer presents some interesting findings connected to the layer morphology, which can be of high interest for practical application for the reason of better layer quality as well as surface layer properties. Limitation of surface damage including irregular shaped pinholes and numerous cracks is of very high importance for decreasing the influence of pitting corrosion onto the surface layer corrosion resistance in very width range o applications.Originality/value: The value of this paper is to define the influence of heat treatment parameters and aluminium addition on corrosion resistance properties of magnesium-aluminium cast alloys.

L.A. Dobrza?ski

2011-01-01

284

Corrosion resistance of Elektron 21 magnesium alloy  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: Elektron 21 magnesium alloy containing neodymium, gadolinium and zinc has high strength, good corrosion resistance and excellent castability. It is designed mainly for aerospace applications. The purpose of the investigation was to study the corrosion resistance of Elektron 21 magnesium alloy in as cast condition and after heat treatment in 3.5% NaCl saturated with Mg(OH2 solution.Design/methodology/approach: Solution treatment was performed at 525°C/8h/water, while ageing treatments at following conditions 250°C/4-96h/air. Immersion test was performed in 3.5% NaCl saturated with Mg(OH2 solution at room temperature. Specimens were placed in 3.5% NaCl solution for periods of time between one and 5 days. After immersion test, the microstructure and the appearances of the corroded structure were examined by optical microscopy (Olympus GX-70 and a scanning electron microscopy (Hitachi S3400.Findings: The corrosion rates of Elektron 21 alloy increased with increasing the exposure time and finally (after 5 days reached maximum value 0.092 mg/cm-2day-1. Solution treatment at 520°C for 8 h caused decrease in corrosion rate (0.072 mg cm-2 day-1 due to dissolving of intermetallic phase precipitates at matrix. Ageing at 200°C for 4h and 16h caused next decrease in corrosion rate to value 0.052 and 0,055 mg cm-2 day-1 respectively, while after ageing for 48h corrosion rate increase to value 0.067 mg cm-2 day-1, due to increase of volume fraction and size of ?’ phase and precipitations of equilibrium ? phase. It was also noticed that the longer time of ageing the higher corrosion rates were observed.Research limitations/implications: Future researches should include investigations of the influence of other environments on the corrosion resistance of Elektron 21 alloy.Practical implications: The improvement of corrosion resistance of Elektron 21 alloy can cause increase in it application in aerospace industry.Originality/value: The relationship between the ageing parameters, microstructure and corrosion resistance in Elektron 21 magnesium alloy was specified.

A. Kie?bus

2007-05-01

285

Model studies of erosion corrosion at saturated steam turbine components  

International Nuclear Information System (INIS)

Erosion corrosion arising in the high-pressure section of saturated steam turbines at non-rotating components of non-alloyed or cast steels essentially effects maintenance strategy and revision cycles being realizable in nuclear power plant turbines. With regard to the large variety of influencing factors, on which an erosion corrosion wear is dependent through longer operating periods, experimentally supported research works in various countries aim at establishing sufficiently exact empirical computation models for erosion corrosion wear under various conditions. The model studies incorporated into these efforts and carried out at the erosion corrosion test facility of the Dresden University of Technology operating since 1986 are intended to result in a computation model having sufficient precision for the operational conditions of the nuclear power station turbines employed in the GDR. (author)

286

Corrosion-resistant nickel-base alloys for gas turbines  

Energy Technology Data Exchange (ETDEWEB)

Laboratory corrosion screening procedures used during the past ten years in developing nickel-base superalloys for gas turbine applications are described. Hot salt corrosion tests have included crucible and salt shower exposures. Reproducible techniques were established and alloy composition effects defined, leading to development of M313, IN-587, a IN-792. Correlations have been made with corrosion results in burner rigs, and engine experience confirming anticipated behavior is now becoming available. During this work a number of limitations of these accelerated laboratory tests were uncovered; these are discussed. Finally, brief descriptions of the states of development of alloy MA 755E (an oxide dispersion-strengthened superalloy) and IN-939 (a cast 23 percent chromium superalloy) are outlined as examples of advanced corrosion resistant, high strength materials of the future.

Schultz, J.W.; Hulsizer, W.R.

1976-08-01

287

Removable cast partial dentures.  

Science.gov (United States)

In planning treatment for partially edentulous patients, the dentist is often confronted with conditions that preclude fixed prosthodontics. In these instances the cast removable partial denture is often the alternative of choice. In planning and producing a removable partial denture that will be most satisfactory, a systematic evaluation at the very beginning of treatment can prevent many problems that often occur when planning is limited. PMID:7746614

Ruffino, A R

1995-03-01

288

The vascular endothelium / El endotelio vascular  

Scientific Electronic Library Online (English)

Full Text Available SciELO Peru | Language: English Abstract in spanish La investigación sobre el endotelio vascular en los últimos 40 años ha provisto ideas para entender la enfermedad vascular. Este nuevo conocimiento ha encontrado su camino en la medicina clínica. En esta revisión nos ocupamos de ciertas áreas de la investigación en las que se ha obtenido avances sig [...] nificativos en la prevención y el tratamiento cardiovascular, así como algunas interrogantes que aún permanecen sin respuesta. Abstract in english Over the last 40 years, research on the vascular endothelium has provided important clues for the understanding of vascular disease. This new knowledge is finding its way into clinical medicine. In this review we deal with some areas where significant advances in the prevention and treatment of card [...] iovascular research has been achieved and with some of the remaining questions.

Salvador, Moncada.

2014-10-01

289

Bimetallic layered castings alloy steel – carbon cast steel  

Directory of Open Access Journals (Sweden)

Full Text Available In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast processso-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer. The bearing part of bimetallic layered casting is typical foundry material i.e. ferritic-pearlitic carbon cast steel, whereas working part (layer is plate of austenitic alloy steel sort X10CrNi 18-8. The ratio of thickness between bearing and working part is 8:1. The quality of the bimetallic layered castings was evaluated on the basis of ultrasonic NDT (non-destructive testing, structure and macro- and microhardness researches.

T. Wróbel

2011-01-01

290

The mutual co-regulation of extracellular polymeric substances and iron ions in biocorrosion of cast iron pipes.  

Science.gov (United States)

New insights into the biocorrosion process may be gained through understanding of the interaction between extracellular polymeric substances (EPS) and iron. Herein, the effect of iron ions on the formation of biofilms and production of EPS was investigated. Additionally, the impact of EPS on the corrosion of cast iron coupons was explored. The results showed that a moderate concentration of iron ions (0.06 mg/L) promoted both biofilm formation and EPS production. The presence of EPS accelerated corrosion during the initial stage, while inhibited corrosion at the later stage. The functional groups of EPS acted as electron shuttles to enable the binding of iron ions. Binding of iron ions with EPS led to anodic dissolution and promoted corrosion, while corrosion was later inhibited through oxygen reduction and availability of phosphorus from EPS. The presence of EPS also led to changes in crystalline phases of corrosion products. PMID:25069092

Jin, Juntao; Guan, Yuntao

2014-10-01

291

Casting larger polycrystalline silicon ingots  

Energy Technology Data Exchange (ETDEWEB)

Solarex has developed and patented a directional solidification casting process specifically designed for photovoltaics. In this process, silicon feedstock is melted in a ceramic crucible and solidified into a large grained semicrystalline silicon ingot. In-house manufacture of low cost, high purity ceramics is a key to the low cost fabrication of Solarex polycrystalline wafers. The casting process is performed in Solarex designed casting stations. The casting operation is computer controlled. There are no moving parts (except for the loading and unloading) so the growth process proceeds with virtually no operator intervention Today Solarex casting stations are used to produce ingots from which 4 bricks, each 11.4 cm by 11.4 cm in cross section, are cut. The stations themselves are physically capable of holding larger ingots, that would yield either: 4 bricks, 15 cm by 15 an; or 9 bricks, 11.4 cm by 11.4 an in cross-section. One of the tasks in the Solarex Cast Polycrystalline Silicon PVMaT Program is to design and modify one of the castings stations to cast these larger ingots. If successful, this effort will increase the production capacity of Solarex`s casting stations by 73% and reduce the labor content for casting by an equivalent percentage.

Wohlgemuth, J.; Tomlinson, T.; Cliber, J.; Shea, S.; Narayanan, M.

1995-08-01

292

Contemporary art casting’s education in Guangdong  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Based on the practical experience of establishing three art casting laboratories in three different colleges of Guangdong, this paper focuses on the development of contemporary art casting’s education. By analyzing the reason for the shortage of professionals nowadays and the characteristics of modern foundry industry in the Pearl River Delta, the authors try to find out what kind of knowledge structures a modern foundry industry professional should have. Then, from the viewpoint of educat...

Wu Chunmiao; Ji Qing

2012-01-01

293

Continuous roll casting of aluminium alloys – casting parameters analysis  

Directory of Open Access Journals (Sweden)

Full Text Available The main goal of the paper was to present the influence of casting parameters on casting conditions and interference of casting parameters on the final strip characteristics such as constant strip thickness, surface quality and roughness of aluminum alloys sheet 6,30 to 6,50 mm thick. The study shows that casting speed, roll force and roll gap should have the greatest influence on the final strip thickness, and that the examined parameters agree well with the theoretical standpoints.

E. Krsti? Vukelja

2010-04-01

294

Zinc-The key to preventing corrosion  

Science.gov (United States)

Centuries before it was identified as an element, zinc was used to make brass (an alloy of zinc and copper) and for medicinal purposes. Metallic zinc and zinc oxide were produced in India sometime between the 11th and 14th centuries and in China in the 17th century, although the discovery of pure metallic zinc is credited to the German chemist Andreas Marggraf, who isolated the element in 1746. Refined zinc metal is bluish-white when freshly cast; it is hard and brittle at most temperatures and has relatively low melting and boiling points. Zinc alloys readily with other metals and is chemically active. On exposure to air, it develops a thin gray oxide film (patina), which inhibits deeper oxidation (corrosion) of the metal. The metal's resistance to corrosion is an important characteristic in its use.

Kropschot, S.J.; Doebrich, Jeff L.

2011-01-01

295

Modelling of Corrosion Cracks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Modelling of corrosion cracking of reinforced concrete structures is complicated as a great number of uncertain factors are involved. To get a reliable modelling a physical and mechanical understanding of the process behind corrosion in needed.

Thoft-christensen, Palle

2010-01-01

296

Modelling of Corrosion Cracks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Modelling of corrosion cracking of reinforced concrete structures is complicated as a great number of uncertain factors are involved. To get a reliable modelling a physical and mechanical understanding of the process behind corrosion in needed.

Thoft-christensen, Palle

2003-01-01

297

Unique intermetallics combat wear and corrosion  

International Nuclear Information System (INIS)

Properties of Tribaloy materials are reviewed. Examination of these materials shows that both high-temperature wear and corrosion resistance are provided by dispersing a hard intermetallic phase in a softer cobalt or nickel-base alloy matrix. The materials are supplied as powders which can be plasma sprayed or hot isostatically pressed into 99.5 percent dense parts. Most grades can be shell mold or investment cast; and Tribaloy welding rods are available for hardfacing applications. Tribaloy powders can also be blended with other powders, such as nickel or Monel. The blend can then be plasma sprayed or compacted by conventional P/M techniques. (U.S.)

298

Corrosion of container materials under clay repository conditions  

International Nuclear Information System (INIS)

The work done in Belgium on steels and a number of corrosion-resistant materials is discussed. Laboratory screening tests have been performed to find candidate container materials. Materials of interest have been further tested in surface clays and are being tested in deep clay formations at the Mol site. These tests have concentrated on characterizations of the clay environment under equilibrium and disturbed conditions. The performance of some materials will be monitored for up to 50000 hours in the form of conventional corrosion specimens. Eventually corrosion and performance tests will be performed on full-size or scaled-down containers. The effects of parameters identified as being important based on characterization of the clay environment will be studied further in the laboratory. Electrochemical measurements and experiments on the effects of gamma radiation have been started. The materials that have been tested in clay environments include corrosion allowance materials - carbon steel, unalloyed cast iron, and cast iron alloyed with silicon and nickel - as well as corrosion resistant materials: AISI 304, 316 and 430 stainless steels; aluminum alloys; nickel 200; Inconel 600 and 625; Incoloy 800; Hastelloy C4 and B; and titanium grades 2 and 7

299

General corrosion, irradiation-corrosion, and environmental-mechanical evaluation of nuclear-waste-package structural-barrier materials. Progress report  

International Nuclear Information System (INIS)

Pacific Northwest Laboratory is studying the general corrosion, irradiation-corrosion, and environmentally enhanced crack propagation of five candidate materials in high-temperature aqueous environments simulating those expected in basalt and tuff repositories. The materials include three cast ferrous materials (ductile cast iron and two low-alloy Cr-Mo cast steels) and two titanium alloys, titanium Grade 2 (commercial purity) and Grade 12 (a Ti-Ni-Mo alloy). The general corrosion results are being obtained by autoclave exposure of specimens to slowly replenished simulated ground water flowing upward through a bed of the appropriate crushed rock (basalt or tuff), which is maintained at the desired test temperature (usually 2500C). In addition, tests are being performed in deionized water. Metal penetration rates of iron-base alloys are being derived by stripping off the corrosion product film and weighing the specimen after the appropriate exposure time. The corrosion of titanium alloy specimens is being determined by weight gain methods. The irradiation-corrosion studies are similar to the general corrosion tests, except that the specimen-bearing autoclaves are held in a 60Co gamma radiation field at dose rates up to 2 x 106 rad/h. For evaluating the resistance of the candidate materials to environmentally enhanced crack propagation, three methods are being used: U-bend and fracture toughness specimens exposed in autoclaves; slow strain rate studies in repository-relevant environments to 3000C; and fatigue crack growth rate studies at ambient pressure and 900C. The preliminary data suggest a 1-in. corrosion allowance for iron-base barrier elements intended for 1000-yr service in basalt or tuff repositories. No evidence has yet been found that titanium Grade 2 or Grade 12 is susceptible to environmentally induced crack propagation or, by extension, to stress corrosion cracking

300

Experiences of corrosion and corrosion protection in seawater systems in the Nordic countries  

International Nuclear Information System (INIS)

A summary is given of the experience of the corrosion resistance of pumps, heat exchangers, valves and pipings in different seawater cooling systems in Scandinavia, including power reactor cooling systems in Finland and Sweden. For pumps and heat exchangers the experience has been so extensive that a clear picture of today's standing can be given. Owing to scanty data concerning valves and pipes, the survey of the corrosion in these components is less well supported. Vertically extended centrifugal pumps are the pumps in general use in power plant cooling systems. To counteract corrosion on pump riser and pump casing having an organic surface coating, and on stainless steel shafts and impellers, these components should be provided with internal and external cathodic protection. For tube and plate type heat exchangers, titanium has proved to be the best material choice. Rubber-enclosed carbon steel pipings, or pipings having a thick coating of epoxy plastic, have shown very strong corrosion resistance in power plant seawater cooling systems. Valves in seawater systems have primarily been affected by corrosion due to poorly executed or damaged organic coating on cast iron. Different seawater-resistant bronzes (red bronze, tin bronze and aluminium bronze) are therefore preferable as valve materials

 
 
 
 
301

Study of corrosion-erosion behaviour of stainless alloys in industrial phosphoric acid medium  

Energy Technology Data Exchange (ETDEWEB)

The corrosion and corrosion-abrasion resistance of some stainless steels in industrial phosphoric acid 30% P{sub 2}O{sub 5} has been studied using electrochemical techniques. The corrosion rate of materials increases with the increase of temperature. Alloys which contain chromium, molybdenum and nitrogen in sufficient quantities present the best behaviour. In the abrasion-corrosion conditions, the experimental device set up allowed to follow continually samples electrochemical behaviour. Under dynamic conditions and without solid particles, the increase of acid projection speed has no effect on the alloys corrosion behaviour. The adding of abrasive leads to a general increase of corrosion rate and to a decrease of material resistance. Under these conditions, materials attack is controlled by synergistic effect between the abrasion and the impurities. The cast 30% Cr shows good resistance according to his high chromium content.

Guenbour, Abdellah [Laboratory of Electrochemistry-Corrosion, Av. Ibn Batouta, BP1014-Faculty of Science, Rabat (Morocco)]. E-mail: guenbour@fsr.ac.ma; Hajji, Mohamed-Adil [Group Corrosion and Protection of Materials, ENIM, Rabat (Morocco); Jallouli, El Miloudi [Group Corrosion and Protection of Materials, ENIM, Rabat (Morocco); Bachir, Ali Ben [Laboratory of Electrochemistry-Corrosion, Av. Ibn Batouta, BP1014-Faculty of Science, Rabat (Morocco)

2006-12-30

302

Study of corrosion-erosion behaviour of stainless alloys in industrial phosphoric acid medium  

International Nuclear Information System (INIS)

The corrosion and corrosion-abrasion resistance of some stainless steels in industrial phosphoric acid 30% P2O5 has been studied using electrochemical techniques. The corrosion rate of materials increases with the increase of temperature. Alloys which contain chromium, molybdenum and nitrogen in sufficient quantities present the best behaviour. In the abrasion-corrosion conditions, the experimental device set up allowed to follow continually samples electrochemical behaviour. Under dynamic conditions and without solid particles, the increase of acid projection speed has no effect on the alloys corrosion behaviour. The adding of abrasive leads to a general increase of corrosion rate and to a decrease of material resistance. Under these conditions, materials attack is controlled by synergistic effect between the abrasion and the impurities. The cast 30% Cr shows good resistance according to his high chromium content

303

Modeling tools for concrete casting  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Thanks to the recent advances in the cementitious materials rheology field, existing works allows for the physical quantification of workability of fresh concrete. The objective of this thesis is to develop techniques allowing for the prediction of casting according to these rheological measurements, the geometry of the element to be cast and the selected casting process. The methodology adopted is to isolate and treat each of the involved phenomena in a simpler configuration and then to grad...

Nguyen, Thi Lien Huong

2007-01-01

304

Cast dielectric composite linear accelerator  

Science.gov (United States)

A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.

Sanders, David M. (Livermore, CA); Sampayan, Stephen (Manteca, CA); Slenes, Kirk (Albuquerque, NM); Stoller, H. M. (Albuquerque, NM)

2009-11-10

305

Localized corrosion information using high resolution measurement devices  

DEFF Research Database (Denmark)

High performance demand for several engineering alloys and components, and miniaturization of electronics and development of MEMS requires better understanding of local corrosion characteristics frequently down to µm scale. This is because in metallic materials corrosion is a sensitive function of microstructure, in particular the local electrochemical activities of several microstructural heterogeneities such as second phase particles and grain boundaries. The overall corrosion behaviour of the material is determined by the local interaction of several microstructural features. On the other hand in engineering components, structural heterogeneities of a higher scale could be produced by joining and processing techniques such as welding (eg. heat affected zone and nugget), cutting and machining operations. In all these cases understanding the corrosion properties of an individual microstructural region in conjunction with microstructural analysis, using advanced microscopic tools, becomes very important. Corrosion of microelectronics circuits and MEMs is also a recent problem, which demands measurement resolution down to few microns as the components are extremely small, and measurement needs to be carried out without damaging the entire component. These limitations can be overcome by the use of high resolution corrosion measurement devices, which in various forms are being used by few investigators. One popular approach is the so called microelectrochemical set up, which use a pipette connected to a system to control the solution flow at the tip. Through addition of reference and counter electrodes, the pipette system becomes a microscopic electrochemical cell, which can then be used with high precision to determine the electrochemical characteristics of the microstructural region of interest. The capability of the technique could be further enhanced by adding new features such as high resolution video visualization systems, fretting/tribo-corroson attachments, and also by integrating it with stress corrosion testing, corrosion investigation of concrete for a few to name with. The corrosion group in MPT, Technical University of Denmark has developed various types of microelectrochemical devices with resolutions 1 mm - 10 ?m; also integrated them with stress corrosion testing, fretting corrosion measurements and potential profiling for complex geometries such as die-cast and engine components. This paper describe the methods and the results of local corrosion investigations of aluminium alloy microstructure, friction stir welds, spot-welds, cast components and microelectronic devices.

Ambat, Rajan

2005-01-01

306

Erosion-corrosion  

International Nuclear Information System (INIS)

A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment

307

Fracture Mechanisms in Steel Castings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The investigations were inspired with the problem of cracking of steel castings during the production process. A single mechanism of decohesion - the intergranular one - occurs in the case of hot cracking, while a variety of structural factors is decisive for hot cracking initiation, depending on chemical composition of the cast steel. The low-carbon and low-alloyed steel castings crack due to the presence of the type II sulphides, the cause of cracking of the high-carbon tool cast steels is ...

Stradomski, Z.; Stachura, S.; Stradomski, G.

2013-01-01

308

Corrosion testing of selected packaging materials for disposal of high-level waste glass in rock-salt formations  

International Nuclear Information System (INIS)

In previous corrosion studies performed in salt brines, unalloyed steels, Ti 99.8-Pd and Hastelloy C4 have proved to be the most promising materials for long-term resistant packagings to be used in heat-generating waste (vitrified HLW, spent fuel) disposal in rock-salt formations. Investigations of the iron-base materials Ni-Resist D2 and D4, cast iron and Si-cast iron have also been carried out in order to complete the results available to date. The three steels (fine-grained steel, low-carbon steel, cast steel) investigated and Ti 99.8-Pd resisted pitting and crevice corrosion as well as stress-corrosion cracking under all test conditions. Gamma dose-rates of 1 Gy/h - 100 Gy/h or H2S concentrations in the brines as well as welding and explosion plating did not influence noticeably the corrosion behaviour of the materials. Furthermore, the determined corrosion rates of the steels (50 ?m/a-250 ?m/a, depending on the test conditions) are intercomparable and imply technically acceptable corrosion allowances for the thick-walled containers discussed. For Ti 99.8-Pd no detectable corrosion was observed. By contrast, Hastelloy C4 proved susceptible to pitting and crevice corrosion at gamme dose-rates higher than 1 Gy/h and in the presence of H2S (25 mg/l) in Q-brine. The materials Ni Resist D2 and D4, cast iron and Si-cast iron corroded at negligible rates in the in-situ experiments performed in rock salt/limited amounts of NaCI-brine. Nevertheless, these materials must be ruled out as container materials because they have proved to be susceptible to pitting and intergranular corrosion in previous laboratory studies conducted with MgCI2-rich brine (Q-brine) in excess. 15 refs.; 29 figs.; 7 tabs

309

The anaerobic corrosion of carbon steel in concrete  

International Nuclear Information System (INIS)

The report describes the work of a two year programme investigating the anaerobic corrosion of carbon steel embedded in a range of candidate repository cements and concretes at laboratory ambient temperatures. The factors investigated in the study were the rate of the anaerobic corrosion reaction, the effect of hydrogen overpressure on the reaction rate and the form of the corrosion product. Both electrochemical and sample weight loss corrosion rate measurements were used. The cements and concretes used were prepared both with and without small additions of chloride (2% by weight of mix water). The results indicate that the corrosion rate is low, <1 ?m/year, the effect of hydrogen overpressure is not significant over the range of pressures investigated, 1-100 atmospheres, and that the corrosion product is dependent on the cement used to cast the samples. Magnetite was identified in the case of blast furnace slag replacement cements but for pulverised fuel ash and ordinary Portland cements no corrosion product was evident either from X-ray diffraction or laser Raman measurements. (Author)

310

Cast iron-base alloy for cylinder/regenerator housing  

Science.gov (United States)

NASACC-1 is a castable iron-base alloy designed to replace the costly and strategic cobalt-base X-40 alloy used in the automotive Stirling engine cylinder/generator housing. Over 40 alloy compositions were evaluated using investment cast test bars for stress-rupture testing. Also, hydrogen compatibility and oxygen corrosion resistance tests were used to determine the optimal alloy. NASACC-1 alloy was characterized using elevated and room temperature tensile, creep-rupture, low cycle fatigue, heat capacity, specific heat, and thermal expansion testing. Furthermore, phase analysis was performed on samples with several heat treated conditions. The properties are very encouraging. NASACC-1 alloy shows stress-rupture and low cycle fatigue properties equivalent to X-40. The oxidation resistance surpassed the program goal while maintaining acceptable resistance to hydrogen exposure. The welding, brazing, and casting characteristics are excellent. Finally, the cost of NASACC-1 is significantly lower than that of X-40.

Witter, Stewart L.; Simmons, Harold E.; Woulds, Michael J.

1985-01-01

311

Formation of intermetallic compound coating on magnesium AZ91 cast alloy  

International Nuclear Information System (INIS)

This study describes an intermetallic compound coating formed on AZ91 Mg cast alloy. The Al sputtered on AZ91 cast alloy reacted with substrate during a short period of heat treatment at 435 deg. C, resulting in the formation of a continuous intermetallic compound layer. The short period treatment has the advantage of minimizing the negative effect on the microstructure of substrate and the mechanical properties, comparing with the reported diffusion coatings. DSC measurement and examination on the cross-section of Al sputtered samples show that local melting occurred along the Al/substrate interface at the temperature range between 430?435 deg. C. The formation mechanism of intermetallic compound coating is proposed in terms of the local melting at Al/substrate interface. The salt water immersion test showed significant improvement in corrosion resistance of the intermetallic compound coated AZ91 cast alloy compared with the as-cast alloys.

312

Formation of intermetallic compound coating on magnesium AZ91 cast alloy  

Science.gov (United States)

This study describes an intermetallic compound coating formed on AZ91 Mg cast alloy. The Al sputtered on AZ91 cast alloy reacted with substrate during a short period of heat treatment at 435°C, resulting in the formation of a continuous intermetallic compound layer. The short period treatment has the advantage of minimizing the negative effect on the microstructure of substrate and the mechanical properties, comparing with the reported diffusion coatings. DSC measurement and examination on the cross-section of Al sputtered samples show that local melting occurred along the Al/substrate interface at the temperature range between 430~435°C. The formation mechanism of intermetallic compound coating is proposed in terms of the local melting at Al/substrate interface. The salt water immersion test showed significant improvement in corrosion resistance of the intermetallic compound coated AZ91 cast alloy compared with the as-cast alloys.

Zhu, Tianping; Gao, Wei

2009-08-01

313

Formation of intermetallic compound coating on magnesium AZ91 cast alloy  

Energy Technology Data Exchange (ETDEWEB)

This study describes an intermetallic compound coating formed on AZ91 Mg cast alloy. The Al sputtered on AZ91 cast alloy reacted with substrate during a short period of heat treatment at 435 deg. C, resulting in the formation of a continuous intermetallic compound layer. The short period treatment has the advantage of minimizing the negative effect on the microstructure of substrate and the mechanical properties, comparing with the reported diffusion coatings. DSC measurement and examination on the cross-section of Al sputtered samples show that local melting occurred along the Al/substrate interface at the temperature range between 430{approx}435 deg. C. The formation mechanism of intermetallic compound coating is proposed in terms of the local melting at Al/substrate interface. The salt water immersion test showed significant improvement in corrosion resistance of the intermetallic compound coated AZ91 cast alloy compared with the as-cast alloys.

Zhu Tianping; Gao Wei, E-mail: tzhu004@aucklanduni.ac.nz [Department of Chemical and Materials Engineering, University of Auckland (New Zealand)

2009-08-15

314

Development of high performance cast stainless steels for ITER shield module applications  

Science.gov (United States)

Casting of austenitic stainless steels offers the possibility of directly producing large and/or relatively complex structures, such as the first wall shield modules or the divertor cassette for the ITER, which may lead to simpler component fabrication and major cost savings. Past efforts to use cast steel for these large components were unsuccessful due to lower than acceptable strength in the test components. To improve and validate cast stainless steel as a substitute for wrought stainless steel for shield module applications, a series of test cast steels based on the commercially available CF3M specification have been designed and fabricated. These modifications utilize combinations of Mn and N, which result in significant increases in strength, fracture toughness, and impact properties. These mechanical performance improvements have been achieved without any loss of irradiation performance, corrosion performance, or weldability.

Busby, J. T.; Maziasz, P. J.; Rowcliffe, A. F.; Santella, M.; Sokolov, M.

2011-10-01

315

Corrosion resistance of oxy-nitrided and oxy-nitro-carburized layers; Resistance a la corrosion des couches oxynitrurees et oxynitrocarburees  

Energy Technology Data Exchange (ETDEWEB)

Nitridation treatments are broadly used in mechanic industries to improve friction behavior and the resistance to wear and fatigue of steel and cast iron parts. Since 1980 technical studies have shown that these treatments can also improve the resistance to corrosion and this technique has been applied to the cladding of control rods of nuclear reactors. New treatments or treatments involving particular operations such as oxidation, smoothing, impregnation and passivation have been developed to improve both mechanical properties and the resistance to corrosion of nitrided layers. In this article we describe 2 kinds of treatment: oxy-nitridation and oxy-nitro-carburization and their performances against corrosion. (A.C.) 18 refs.

Vermesan, G.; Lieurade, H.P.; Duchateau, D.; Ghiglione, D.; Peyre, J.P

1998-04-01

316

Phase transformations in cast duplex stainless steels  

Science.gov (United States)

Duplex stainless steels (DSS) constitute both ferrite and austenite as a matrix. Such a microstructure confers a high corrosion resistance with favorable mechanical properties. However, intermetallic phases such as sigma (sigma) and chi (chi) can also form during casting or high-temperature processing and can degrade the properties of the DSS. This research was initiated to develop time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams of two types of cast duplex stainless steels, CD3MN (Fe-22Cr-5Ni-Mo-N) and CD3MWCuN (Fe-25Cr-7Ni-Mo-W-Cu-N), in order to understand the time and temperature ranges for intermetallic phase formation. The alloys were heat treated isothermally or under controlled cooling conditions and then characterized using conventional metallographic methods that included tint etching, and also using electron microscopy (SEM, TEM) and wavelength dispersive spectroscopy (WDS). The kinetics of intermetallic-phase (sigma + chi) formation were analyzed using the Johnson-Mehl-Avrami (JMA) equation in the case of isothermal transformations and a modified form of this equation in the case of continuous cooling transformations. The rate of intermetallic-phase formation was found to be much faster in CD3MWCuN than CD3MN due mainly to differences in the major alloying contents such as Cr, Ni and Mo. To examine in more detail the effects of these elements of the phase stabilities, a series of eight steel castings was designed with the Cr, Ni and Mo contents systematically varied with respect to the nominal composition of CD3MN. The effects of varying the contents of alloying additions on the formation of intermetallic phases were also studied computationally using the commercial thermodynamic software package, Thermo-Calc. In general, a was stabilized with increasing Cr addition and chi by increasing Mo addition. However, a delicate balance among Ni and other minor elements such as N and Si also exists. Phase equilibria in DSS can be affected by local composition fluctuations in the cast alloy. This may cause discrepancy between thermodynamic prediction and experimental observation.

Kim, Yoon-Jun

317

Corrosion Studies on Concrete Using Treated and Untreated Textile Effluent and Impact of Corrosion Inhibitor  

Directory of Open Access Journals (Sweden)

Full Text Available An attempt was made to use the waste water from textile industry for construction purpose, so that the shortage in water can be greatly reduced and the waste water can be suitably disposed for safe guarding the environment.  The basic properties of the treated and untreated water from the textile industry were tested and the results were found to be satisfactory such that it can be used for construction purposes.  By using the waste water from the textile industry cubes, cylinders and beams were casted and tested for its mechanical properties (compressive strength, tensile strength, flexural strength etc and the result was found to be satisfactory.  Hence the experiment was continued on for durability studies where the corrosion attack was also studied.  The results of other durability studies were found to be satisfactory.  In this experimental study the results of specimen’s casted using treated and untreated textile water were compared with the specimens casted with potable water.  Since there was some corrosion, admixtures were added to counter act the same and the results were found to be satisfactory. 

K Nirmalkumar

2009-02-01

318

Comparison Of Metal Corrosion Inhibition By Gravimetric And Linear Polarization Resistance Methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Studies were conducted to evaluate the effectiveness of various dosages of the selected silicate and phosphate compounds applied for corrosion inhibition of cast iron, copper, lead, and galvanized steel specimens. The compounds selected for study were zinc polyphosphate (Calgon C-39), zinc orthophosphate (Virchem V-931), sodium metasilicate and glassy silicate. The effectiveness of these compounds for corrosion inhibition were studied under differing water quality conditions using gravimetric...

Banerji, Shankha

1992-01-01

319

The corrosion resistance of titanium - ruthenium alloys in hydrochloric acid media  

International Nuclear Information System (INIS)

Alloys of the Ti-Ru system in the cast state and in the annealed state have been investigated. The investigated samples were prepared by the method of induction melting in the helium atmosphere. The corrosion resistance was investigated by the weight method in the solution of hydrochloric acid. The results of the corrosion experiments were calculated as a mean value of two parallel samples. 2 tabs., 4 refs

320

Increased corrosion resistance of the AZ80 magnesium alloy by rapid solidification.  

Science.gov (United States)

Magnesium (Mg) and Mg-alloys are being considered as implantable biometals. Despite their excellent biocompatibility and good mechanical properties, their rapid corrosion is a major impediment precluding their widespread acceptance as implantable biomaterials. Here, we investigate the potential for rapid solidification to increase the corrosion resistance of Mg alloys. To this end, the effect of rapid solidification on the environmental and stress corrosion behavior of the AZ80 Mg alloy vs. its conventionally cast counterpart was evaluated in simulated physiological electrolytes. The microstructural characteristics were examined by optical microscopy, SEM, TEM, and X-ray diffraction analysis. The corrosion behavior was evaluated by immersion, salt spraying, and potentiodynamic polarization. Stress corrosion resistance was assessed by Slow Strain Rate Testing. The results indicate that the corrosion resistance of rapidly solidified ribbons is significantly improved relative to the conventional cast alloy due to the increased Al content dissolved in the ?-Mg matrix and the correspondingly reduced presence of the ?-phase (Mg17 Al12 ). Unfortunately, extrusion consolidated solidified ribbons exhibited a substantial reduction in the environmental performance and stress corrosion resistance. This was mainly attributed to the detrimental effect of the extrusion process, which enriched the iron impurities and increased the internal stresses by imposing a higher dislocation density. In terms of immersion tests, the average corrosion rate of the rapidly solidified ribbons was alloy and 26 mm/year for the rapidly solidified extruded ribbons. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2014. PMID:25491147

Aghion, E; Jan, L; Meshi, L; Goldman, J

2014-12-10

 
 
 
 
321

Effects of friction reducing additives on the corrosion of metals in aqueous solutions. [Cast iron GG 25; unalloyed steel DIN 1. 0333; AlMg 3; CuZn 39 Pb 3; Cu]. Die Wirkung von reibungsmindernden Zusaetzen auf die Metallkorrosion in waessrigen Medien  

Energy Technology Data Exchange (ETDEWEB)

It is known that small additions of certain chemical agents to water can significantly alter its flow behaviour ('drag reducing additives'). Such solutions show also different mass transfer properties as compared with pure water. Since corrosion reactions are frequently mass transfer controlled it might be expected, that drag reducers will affect the metal corrosion as well. In order to get more insight into the subject, various experiments with several substances known as drag reducing agents were performed (hexadecyltrimethyl-ammoniumsalicylate and two commercially available cationic tensides). The experimental techniques used were rotating disc electrodes and corrosion tests with segmented tube as a corrosion sample. The results obtained indicate that the products tested indeed reduce the rate of corrosion of different materials, this due to partly interfering with the mass transfer of oxygen, or/and acting directly as a corrosion inhibitor. In addition, a synergic effect with other conventional water treatment chemicals, was observed. Certain problems with respect to the practical use of such additives (e.g. in district heating systems) are discussed. (orig.).

Weber, J.; Knopf, K. (Sulzer-Innotec, Winterthur (Switzerland))

1991-07-01

322

Colour Metallography of Cast Iron - White Cast Iron (?  

Directory of Open Access Journals (Sweden)

Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour metallographic photos. Except for focusing on the effect of high carbon phases in cast iron, in this book, special attention is also paid to the effect of austenite on solidification, graphite morphology, and quality of cast iron; at the same time, the study on the solidification behaviours in the region around eutectic cells and its effects on mechanical properties of cast iron, are also emphasized.

Zhou Jiyang

2011-11-01

323

Colour Metallography of Cast Iron - Chapter 5: White Cast Iron (?  

Directory of Open Access Journals (Sweden)

Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour metallographic photos.Except for focusing on the effect of high carbon phases in cast iron, in this book, special attention is also paid to the effect of austenite on solidification, graphite morphology, and quality of cast iron; at the same time, the study on the solidification behaviours in the region around eutectic cells and its effects on mechanical properties of cast iron, are also emphasized.

Zhou Jiyang

2011-08-01

324

Cast Fe-base cylinder/regenerator housing alloy  

Science.gov (United States)

The development of an iron-base alloy that can meet the requirements of automotive Stirling engine cylinders and regenerator housings is described. Alloy requirements are as follows: a cast alloy, stress for 5000-hr rupture life of 200 MPa (29 ksi) at 775 C (1427 F), oxidation/corrosion resistance comparable to that of N-155, compatibility with hydrogen, and an alloy cost less than or equal to that of 19-9DL. The preliminary screening and evaluation of ten alloys are described.

Larson, F.; Kindlimann, L.

1980-01-01

325

The influence of carbon and copper on the solidification process of the ferritic-austenitic cast steel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Technological problems which occur during the production of castings made of ferritic-austenitic (duplex) cast steel have caused that this most modern material among corrosion-resistant cast steels is seldom produced in Poland. The main reason of arising problems is the necessity of achieving a very low carbon content (Cmax = 0.03%, according to PN-EN 10283:2004) and the occurring of hot cracking. It is impossible for our domestic foundries to achieve such a low carbon content, because it dem...

Stradomska, J.

2009-01-01

326

Towards Corrosion Detection System  

Directory of Open Access Journals (Sweden)

Full Text Available Corrosion is a natural process that seeks to reduce the binding energy in metals. The end result of corrosion involves a metal atom being oxidized. Surface corrosion on aluminum aircraft skins, near joints and around fasteners, is often an indicator of buried structural corrosion and cracking In this paper we proposed a new method on which we are moving towards designing a method to detect the corrosion within the metals, the new method has defined texture analysis as the main method for this approach, the proposed enhancement shows less false positive and less false negative. The main functions used in this approach beside texture analysis are Edge detection, structure element and image dilation. The new approach has designed to detect a part of the image that has been affected by the corrosion, the tested images has showed a good result lying on detecting the corrosion part from the image.

B.B.Zaidan

2010-05-01

327

Scheduled Caste Women: Problems And Challenges  

Directory of Open Access Journals (Sweden)

Full Text Available The paper analyzed the Caste system based on Varnas during the ancient India. It also examined the demerits of caste attached to the present scheduled castes in general and scheduled caste women in particular. The scheduled caste women are disadvantaged by their caste and gender and as such they are subject to exploitation and discrimination by their family members, by their caste people and by forward castes. Hence, there is increase in exploitation, discrimination and violence against the scheduled caste women. The female feticide, illiteracy, gender inequality, Devadasi, Jogini practice, Nude Service to Deity, different types of violence, dowry, child marriage, etc are few of the problems faced by scheduled caste women in present society. Statistics of the violence acts against the scheduled caste women is discussed in the paper and there is need to strictly enforce the legislations passed to protect the violence against scheduled caste women. For this purpose, there is need of enquiry from lady police officials.

Vijayakumar Murthy

2013-12-01

328

Corrosion of candidate container materials in air-steam mixtures  

International Nuclear Information System (INIS)

The environment during the operating period of a high-level nuclear waste repository in basalt is expected to be air saturated with steam. Liquid groundwater is not expected to be in contact with the container surface during that time. The report presents corrosion findings from tests conducted for one to twenty-five months in an air-steam environment. Tests were carried out with bare metal specimens exposed to an air atmosphere containing 12% moisture in chambers maintained at temperatures between 150/degree/C and 300/degree/C. Cast carbon steel exhibited total penetrations less than 0.002 mm for exposures up to 25 months. A ferritic alloy steel, Fe9Cr1Mo, showed corrosion results very similar to cast carbon steel. Unalloyed copper materials showed essentially linear corrosion rates, with total penetrations between 0.002 mm at 150/degree/C and 0.14 mm at 300/degree/C in 25 months. Cupronickel 90-10 exhibited total penetrations between 0.001 mm at 150/degree/C and 0.05 mm at 300/degree/C in 25 months. There was a tendency for the corrosion rate to increase with time for cupronickel at 250/degree/C and 300/degree/C possibly because of a mid-test change in the corrosion mechanism. Limited testing of specimens surrounded with bentonite/basalt packing material indicated that the presence of packing has no strong effect on the corrosion of iron-base materials; however, copper-base and cupronickel materials corroded at higher rates in the presence of packing, with a possiblin the presence of packing, with a possible shift towards the lower bare specimen corrosion rates with increasing time. 8 refs., 5 figs., 3 tabs

329

Vascular Plant Image Gallery  

Science.gov (United States)

Texas A&M University's Bioinformatics Working Group offers this no-nonsense botany teaching resource. Vascular plants are arranged alphabetically by family from Acanthaceae to Zygophyllaceae and users simply click for the images. Brief descriptions are provided (which may indicate the popular name of the plant). The site is searchable. Familiarity with vascular plant taxonomic nomenclature is assumed.

Manhart, James R.

330

Management of vascular trauma  

International Nuclear Information System (INIS)

Objective: To characterize the vascular injuries, their management and the results. Subjects and Methods: Cases of vascular injuries received at the hospital amongst the total of 3134 trauma patients were evaluated. Thirty six cases with 41 vascular lesions were evaluated, excluding the three primary amputations. Vascular injuries were then characterized by age, gender, site, mechanism, associated injuries, need and type of surgery. Results: Penetrating trauma accounted for 94.4% of all vascular admissions. Five percent of the vascular injuries developed complications. Surgical intervention was required in all cases (100%). Reverse saphenous vein graft was used in 82.9%. The injured veins were mostly ligated except one, which was managed by saphenous vein graft. The average time lapsed between injury and intervention of patients ranged between 2 to 18 hours. No mortality or secondary hemorrhage was documented. Conclusion: Vascular trauma represents a small percentage of all trauma admissions. It has a high morbidity and most require surgical intervention. The operative intervention rates are higher in patients with vascular injuries than in the general trauma population but with prompt surgery, the chances of limb salvage increases and the overall complication rate reduces. (author)

331

Continuous casting of hollow billets  

International Nuclear Information System (INIS)

Continuous casting technology of hollow billets has been developed for near-net-shape casting of pipe. A cylindrical water cooled copper mould was used as a core to make a hole at the center of the round billet, while the hot-top casting technique was applied in order to provide space for the submerged entry nozzle and to cast tube blanks of thin wall thickness. A pilot scale casting of a 160mm-diameter billet, which has a 100mm-diameter hole, was conducted and the metallurgical investigation of the billet quality and the numerical analysis were performed to determine the optimum casting conditions. The hot-top casting technique, in which the induction heating (IH) of the oscillating ceramic mould stabilizes the solidification start level, enables both the smooth surface and the thin wall thickness of the hollow billet. The combination of the IH type hot-top casting technique and a water cooled copper mould, create a favourable condition at the shell exterior for generating equiaxed crystal as both fluid flow and thermal conditions, promote high equiaxed structure ratio and elimination of macrosegregation in hollow billets. (author)

332

Education and Caste in India  

Science.gov (United States)

This paper analyses the policy of reservation for lower castes in India. This policy is similar to that of affirmative action in the United States. The paper provides a brief overview of the caste system and discusses the types of groups that are eligible for reservation, based on data from government reports. The stance of this paper is that…

Chauhan, Chandra Pal Singh

2008-01-01

333

Electrochemical corrosion testing: An effective tool for corrosion inhibitor evaluation  

Energy Technology Data Exchange (ETDEWEB)

Corrosivity of an Antifreeze/Coolant can lead to localized attacks which are a major cause for metal failure. To prevent this phenomenon, specific corrosion inhibitors are used to protect the different metals in service. This paper will discuss the electrochemical principles behind corrosion, Realized corrosion and corrosion inhibition. It will also discuss electrochemical techniques which allow for the evaluation of these inhibitors.

Bartley, L.S.; Van de Ven, P.; Mowlem, J.K. [Texaco R& D, Beacon, NY (United States)

1996-10-01

334

Colour Metallography of Cast Iron  

Directory of Open Access Journals (Sweden)

Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron.Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron , uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditionalmaterials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour metallographic photos.Except for focusing on the effect of high carbon phases in cast iron, in this book, special attention is also paid to the effect of austenite on solidification, graphite morphology, and quality of cast iron; at the same time, the study on the solidification behaviours in the region around eutectic cells and its effects on mechanical properties of cast iron, are also emphasized.

Zhou Jiyang

2009-05-01

335

Cast and splint immobilization: complications.  

Science.gov (United States)

During the past three decades, internal fixation has become increasingly popular for fracture management and limb reconstruction. As a result, during their training, orthopaedic surgeons receive less formal instruction in the art of extremity immobilization and cast application and removal. Casting is not without risks and complications (eg, stiffness, pressure sores, compartment syndrome); the risk of morbidity is higher when casts are applied by less experienced practitioners. Certain materials and methods of ideal cast and splint application are recommended to prevent morbidity in the patient who is at high risk for complications with casting and splinting. Those at high risk include the obtunded or comatose multitrauma patient, the patient under anesthesia, the very young patient, the developmentally delayed patient, and the patient with spasticity. PMID:18180390

Halanski, Matthew; Noonan, Kenneth J

2008-01-01

336

Surface films and corrosion of copper  

International Nuclear Information System (INIS)

In Sweden and Finland the spent nuclear fuel is planned to be encapsulated in cast iron canisters that have an outer shield made of copper. The copper shield is responsible for the corrosion protection of the canister construction. General corrosion of the copper is not expected to be the limiting factor in the waste repository environment when estimating the life-time of the canister construction. However, different forms of localised corrosion, i.e. pitting, stress corrosion cracking, or environmentally assisted creep fracture may cause premature failure of the copper shield. Of the probable constituents in the groundwater, nitrites, chlorides, sulphides and carbonates have been suggested to promote localised corrosion of copper. The main assumption made in planning this research program is that the surface films forming on copper in the repository environment largely determine the susceptibility of copper to the different forms of localised corrosion. The availability of reactants, which also may become corrosion rate limiting, is investigated in several other research programs. This research program consists of a set of successive projects targeted at characterising the properties of surface films on copper in repository environment containing different detrimental anions. A further aim was to assess the significance of the anion-induced changes in the stability of the oxide films with regard to localised corrosion of copper. This report summarises the results from a series of investigations on properties of surface films forming on copper in water of pH = 8.9 at temperature of 80 deg C and pressure of 2 MPa. The main results gained so far in this research program are as follows: The surface films forming on copper in the thermodynamic stability region of monovalent copper at 80 deg C consist of a bulk part (about 1 mm thick) which is a good ionic and electronic conductor, and an outer, interfacial layer (0.001 - 0.005 mm thick) which shows p-type semiconductor properties. The thin outer layer controls the corrosion properties of copper, corrosion rate being limited by ionic transport through the layer and the charge transfer step of the film dissolution. Chlorides cause a breakdown of the oxide film in the stability region of divalent copper, but they seem to have no effect on the properties of the film in the stability region of monovalent copper; oxidising conditions with simultaneous exposure to chlorides are thus expected to subject copper to localised corrosion. Sulphides at the concentration of 10 ppm dissolved H2S were found not to promote the formation of a three-dimensional film of Cu2S (or other copper sulphides), thus the mechanisms of localised corrosion which operate under reducing conditions and are based on the formation of copper sulphides seem not to be valid. In the presence of 10 ppm H2S the corrosion rate of copper is controlled by the charge transfer step of the dissolution of the outer layer

337

Surface films and corrosion of copper  

Energy Technology Data Exchange (ETDEWEB)

In Sweden and Finland the spent nuclear fuel is planned to be encapsulated in cast iron canisters that have an outer shield made of copper. The copper shield is responsible for the corrosion protection of the canister construction. General corrosion of the copper is not expected to be the limiting factor in the waste repository environment when estimating the life-time of the canister construction. However, different forms of localised corrosion, i.e. pitting, stress corrosion cracking, or environmentally assisted creep fracture may cause premature failure of the copper shield. Of the probable constituents in the groundwater, nitrites, chlorides, sulphides and carbonates have been suggested to promote localised corrosion of copper. The main assumption made in planning this research program is that the surface films forming on copper in the repository environment largely determine the susceptibility of copper to the different forms of localised corrosion. The availability of reactants, which also may become corrosion rate limiting, is investigated in several other research programs. This research program consists of a set of successive projects targeted at characterising the properties of surface films on copper in repository environment containing different detrimental anions. A further aim was to assess the significance of the anion-induced changes in the stability of the oxide films with regard to localised corrosion of copper. This report summarises the results from a series of investigations on properties of surface films forming on copper in water of pH = 8.9 at temperature of 80 deg C and pressure of 2 MPa. The main results gained so far in this research program are as follows: The surface films forming on copper in the thermodynamic stability region of monovalent copper at 80 deg C consist of a bulk part (about 1 mm thick) which is a good ionic and electronic conductor, and an outer, interfacial layer (0.001 - 0.005 mm thick) which shows p-type semiconductor properties. The thin outer layer controls the corrosion properties of copper, corrosion rate being limited by ionic transport through the layer and the charge transfer step of the film dissolution. Chlorides cause a breakdown of the oxide film in the stability region of divalent copper, but they seem to have no effect on the properties of the film in the stability region of monovalent copper; oxidising conditions with simultaneous exposure to chlorides are thus expected to subject copper to localised corrosion. Sulphides at the concentration of 10 ppm dissolved H{sub 2}S were found not to promote the formation of a three-dimensional film of Cu{sub 2}S (or other copper sulphides), thus the mechanisms of localised corrosion which operate under reducing conditions and are based on the formation of copper sulphides seem not to be valid. In the presence of 10 ppm H{sub 2}S the corrosion rate of copper is controlled by the charge transfer step of the dissolution of the outer layer 57 refs, 35 figs, 7 tabs

Hilden, J.; Laitinen, T.; Maekelae, K.; Saario, T.; Bojinov, M. [VTT Manufacturing Technology, Espoo (Finland)

1999-03-01

338

Oil ash corrosion  

International Nuclear Information System (INIS)

In this paper a review of experience with oil ash corrosion is presented along with current design practices used to avoid excessive tube wastage. Factors influencing oil ash corrosion include fuel chemistry, boiler operation, and boiler design. These factors are interdependent and determine the corrosion behavior in utility boilers. Oil ash corrosion occurs when vanadium-containing ash deposits on boiler tube surfaces become molten. These molten ash deposits dissolve protective oxides and scales causing accelerated tube wastage. Vanadium is the major fuel constituent responsible for oil ash corrosion. Vanadium reacts with sodium, sulfur, and chlorine during combustion to produce lower melting temperature ash compositions, which accelerate tube wastage. Limiting tube metal temperatures will prevent ash deposits from becoming molten, thereby avoiding the onset of oil ash corrosion. Tube metal temperatures are limited by the use of a parallel stream flow and by limiting steam outlet temperatures. Operating a boiler with low excess air has helped avoid oil ash corrosion by altering the corrosive combustion products. Air mixing and distribution are essential to the success of this palliative action. High chromium alloys and coatings form more stable protective scaled on tubing surfaces, which result in lower oil ash corrosion rates. However, there is not material totally resistant to oil ash corrosion

339

Grain boundary corrosion of copper canister weld material  

International Nuclear Information System (INIS)

The proposed design for a final repository for spent fuel and other long-lived residues in Sweden is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will then be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast inner container fitted inside a corrosion-resistant copper canister. During fabrication of the outer copper canisters there will be some unavoidable grain growth in the welded areas. As grains grow, they will tend to concentrate impurities within the copper at the new grain boundaries. The work described in this report was undertaken to determine whether there is any possibility of enhanced corrosion at grain boundaries within the copper canister, based on the recommendations of the report SKB-TR--01-09 (INIS ref. 32025363). Grain boundary corrosion of copper is not expected to be a problem for the copper canisters in a repository. However, as one step in the experimental verification it is necessary to study grain boundary corrosion of copper in an environment where it may occur. A literature study aimed to find one or several solutions that are aggressive with respect to grain boundary corrosion of copper. Copper specimens cut from welds of real copper canisters where exposed to aerated ammonium hydroxide solution for a period of 14 days at 80 degrees C and 10 bar pressure. The samples were investigated prior to exposure using the scanning Kelvin probe technique to characterize anodic and cathodic areas on the samples. The degree of corrosion was determined by optical microscopy. No grain boundary corrosion could be observed in the autoclave experiments, however, a higher rate of corrosion was observed for the weld material compared to the base material. The work suggests that grain boundary corrosion of copper weld material is most unlikely to adversely affect SKB's copper canisters under the conditions in the repository

340

Grain boundary corrosion of copper canister weld material  

Energy Technology Data Exchange (ETDEWEB)

The proposed design for a final repository for spent fuel and other long-lived residues in Sweden is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will then be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast inner container fitted inside a corrosion-resistant copper canister. During fabrication of the outer copper canisters there will be some unavoidable grain growth in the welded areas. As grains grow, they will tend to concentrate impurities within the copper at the new grain boundaries. The work described in this report was undertaken to determine whether there is any possibility of enhanced corrosion at grain boundaries within the copper canister, based on the recommendations of the report SKB-TR--01-09 (INIS ref. 32025363). Grain boundary corrosion of copper is not expected to be a problem for the copper canisters in a repository. However, as one step in the experimental verification it is necessary to study grain boundary corrosion of copper in an environment where it may occur. A literature study aimed to find one or several solutions that are aggressive with respect to grain boundary corrosion of copper. Copper specimens cut from welds of real copper canisters where exposed to aerated ammonium hydroxide solution for a period of 14 days at 80 degrees C and 10 bar pressure. The samples were investigated prior to exposure using the scanning Kelvin probe technique to characterize anodic and cathodic areas on the samples. The degree of corrosion was determined by optical microscopy. No grain boundary corrosion could be observed in the autoclave experiments, however, a higher rate of corrosion was observed for the weld material compared to the base material. The work suggests that grain boundary corrosion of copper weld material is most unlikely to adversely affect SKB's copper canisters under the conditions in the repository.

Gubner, Rolf; Andersson, Urban; Linder, Mats; Nazarov, Andrej; Taxen, Claes [Corrosion and Metals Research Inst. (KIMAB), Stockholm (Sweden)

2006-01-15

 
 
 
 
341

General and localized corrosion of magnesium alloys: A critical review  

Science.gov (United States)

Magnesium (Mg) alloys as well as experimental alloys are emerging as light structural materials for current, new, and innovative applications. This paper describes the influence of the alloying elements and the different casting processes on the microstructure and performance of these alloys and corrosion. It gives a comprehensible approach for the resistance of these alloys to general, localized and metallurgically influenced corrosion, which are the main challenges for their use. Exposure to humid air with ˜65% relative humidity during 4 days gives 100-150 nm thickness. The film is amorphous and has an oxidation rate less than 0.01 µm/y. The pH values between 8.5 and 11.5 correspond to a relatively protective oxide or hydroxide film; however above 11.5 a passive stable layer is observed. The poor corrosion resistance of many Mg alloys can be due to the internal galvanic corrosion caused by second phases or impurities. Agitation or any other means of destroying or preventing the formation of a protective film leads to increasing corrosion kinetics. The pH changes during pitting corrosion can come from two different reduction reactions: reduction of dissolved oxygen (O) and that of hydrogen (H) ions. Filiform corrosion was observed in the uncoated AZ31, while general corrosion mainly occurred in some deposition coated alloys. Crevice corrosion can probably be initiated due to the hydrolysis reaction. Exfoliation can be considered as a type of intergranular attack, and this is observed in unalloyed Mg above a critical chloride concentration.

Ghali, Edward; Dietzel, Wolfgang; Kainer, Karl-Ulrich

2004-02-01

342

Control of cast iron and casts manufacturing by Inmold method  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper the usability of cast iron spheroidizing process in mould control by ATD method as well as by ultrasonic method were presented. Structure of instrumentation needed for control form performance of cast iron spheroidizing by Inmold method was illustrated. Author, pointed out that amount of magnesium master alloy should obtain 0,8 ÷ 1,0% of mass in form at all. Such quantity of preliminary alloy assure of obtain of nodular graphite in cast iron. In consequence of this, is reduce t...

Pietrowski, S.

2009-01-01

343

Optimization of Sigma Phase Precipitates with Respect to the Functional Properties of Duplex Cast Steel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper presents the results of examination concerning optimization of the ? phase precipitates with respect to the functional properties of ferritic-austenitic cast steel. The examined material comprised two grades of corrosion-resistant cast steel, namely GX2CrNiMoN25-6-3 and GX2CrNiMoCuN25-6-3-3, used for example in elements of systems of wet flue gas desulphurisation in power industry. The operating conditions in media heated up to 70°C and containing Cl- and SO4 ions and solid partic...

Stradomski, Z.; Brodziak-hyska, A.; Kolan, C.

2012-01-01

344

Sigma phase in the cast alloy based on the FeB3BAl intermetallic phase  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper presents study results for cast alloy based on the FeB3BAl intermetallic phase. The study material was Fe-28Al-5Cr-1Mo-0,1Zr-0,005B% at. alloy in the cast state. The microscopic research, phase analysis with X-ray diffraction, bending test and observation of thealloy surface exposed to corrosion have been performed. It has been found that presence of the sigma phase in the material structureinfluences high hardness of the tested alloy, its susceptibility to brittle fracture and favo...

Jasionowski, R.; Haimann, K.; Lachowicz, M.; Podrez-radziszewska, M.

2011-01-01

345

Microstructure Based Modeling of ? Phase Influence on Mechanical Response of Cast AM Series Mg Alloys  

Energy Technology Data Exchange (ETDEWEB)

Magnesium alloys have become popular alternatives to aluminums and steels for the purpose of vehicle light-weighting. However, Mg alloys are hindered from wider application due to limited ductility as well as poor creep and corrosion performance. Understanding the impact of microstructural features on bulk response is key to improving Mg alloys for more widespread use and for moving towards truly predicting modeling capabilities. This study focuses on modeling the intrinsic features, particularly volume fraction and morphology of beta phase present, of cast Mg alloy microstructure and quantifying their impact on bulk performance. Computational results are compared to experimental measurements of cast plates of Mg alloy with varying aluminum content.

Barker, Erin I.; Choi, Kyoo Sil; Sun, Xin; Deda, Erin; Allison, John; Li, Mei; Forsmark, Joy; Zindel, Jacob; Godlewski, Larry

2014-09-30

346

Pediatric vascular access  

International Nuclear Information System (INIS)

Pediatric interventional radiologists are ideally suited to provide vascular access services to children because of inherent safety advantages and higher success from using image-guided techniques. The performance of vascular access procedures has become routine at many adult interventional radiology practices, but this service is not as widely developed at pediatric institutions. Although interventional radiologists at some children's hospitals offer full-service vascular access, there is little or none at others. Developing and maintaining a pediatric vascular access service is a challenge. Interventionalists skilled in performing such procedures are limited at pediatric institutions, and institutional support from clerical staff, nursing staff, and technologists might not be sufficiently available to fulfill the needs of such a service. There must also be a strong commitment by all members of the team to support such a demanding service. There is a slippery slope of expected services that becomes steeper and steeper as the vascular access service grows. This review is intended primarily as general education for pediatric radiologists learning vascular access techniques. Additionally, the pediatric or adult interventional radiologist seeking to expand services might find helpful tips. The article also provides education for the diagnostic radiologist who routinely interprets radiographs containing vascular access devices. (orig.)rig.)

347

Mechanical and corrosion properties of binary Mg–Dy alloys for medical applications  

International Nuclear Information System (INIS)

Microstructure, mechanical and corrosion properties of binary magnesium–dysprosium (Mg-5, 10, 15, 20 wt.% Dy) alloys were investigated for medical applications. In the as-cast condition, the distribution of Dy is quite inhomogeneous. Mg–10Dy alloy exhibits a moderate tensile and compression yield strength, and the best elongation and corrosion resistance. After T4 (solutionizing) treatment, the distribution of Dy becomes homogeneous. The tensile and compression yield strength of all Mg–Dy alloys decreases. The elongation remains unchanged, while the corrosion resistance is largely improved after T4 treatment.

348

Mechanical and corrosion properties of binary Mg-Dy alloys for medical applications  

Energy Technology Data Exchange (ETDEWEB)

Microstructure, mechanical and corrosion properties of binary magnesium-dysprosium (Mg-5, 10, 15, 20 wt.% Dy) alloys were investigated for medical applications. In the as-cast condition, the distribution of Dy is quite inhomogeneous. Mg-10Dy alloy exhibits a moderate tensile and compression yield strength, and the best elongation and corrosion resistance. After T4 (solutionizing) treatment, the distribution of Dy becomes homogeneous. The tensile and compression yield strength of all Mg-Dy alloys decreases. The elongation remains unchanged, while the corrosion resistance is largely improved after T4 treatment.

Yang Lei, E-mail: lei.yang@hzg.de [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Huang Yuanding; Peng Qiuming; Feyerabend, Frank; Kainer, Karl Ulrich; Willumeit, Regine; Hort, Norbert [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany)

2011-12-15

349

Corrosion resistance of oxy-nitrided and oxy-nitro-carburized layers  

International Nuclear Information System (INIS)

Nitridation treatments are broadly used in mechanic industries to improve friction behavior and the resistance to wear and fatigue of steel and cast iron parts. Since 1980 technical studies have shown that these treatments can also improve the resistance to corrosion and this technique has been applied to the cladding of control rods of nuclear reactors. New treatments or treatments involving particular operations such as oxidation, smoothing, impregnation and passivation have been developed to improve both mechanical properties and the resistance to corrosion of nitrided layers. In this article we describe 2 kinds of treatment: oxy-nitridation and oxy-nitro-carburization and their performances against corrosion. (A.C.)

350

Evaluation of cast carbon steel and aluminum for rack insert in MCO Mark 1A fuel basket  

Energy Technology Data Exchange (ETDEWEB)

This document evaluates the effects ofusing a cast carbon steel or aluminum instead of 3O4L stainless steel in the construction ofthe fuel rack insert for the Spent Nuclear Fuel MCO Mark IA fuel baskets. The corrosion, structural, and cost effects are examined.

Graves, C.E., Fluor Daniel Hanford

1997-03-21

351

Resistance to corrosion by water at high temperatures of Al-Fe-Ni alloy after prolonged heat treatment. Influence of Ti and Zr additions  

International Nuclear Information System (INIS)

The influence of titanium and zirconium additions on the heterogeneity texture of Al-Fe-Ni alloys, and the resultant effect on their corrosion resistance, is briefly recalled. The present article records the results of corrosion tests on these alloys after prolonged heat treatment. Without additions, the eutectic structure of the basis alloy is subject to a coalescence, which results in a deterioration of corrosion resistance. This effect applies equally to the as-cast and to the wrought conditions. The addition of titanium or zirconium retards this deterioration very considerably, both for the as-cast and wrought alloys. (author)

352

Corrosion, microstructure, and metallography  

International Nuclear Information System (INIS)

Of the forty-one papers presented, nearly half of them deal with microstructural aspects of corrosion, corrosion control and corrosion failure analysis. They describe various analytical approaches for studying corrosion and for diagnosing corrosion failure mechanisms. Details include microstructural features of corrosion on a wide range of materials or coatings and in environments ranging from within the human body to outer space. Another series of papers handles microstructure-property relationships and contains reports on hydrogen embrittlement of AISI 316 stainless steel, shell and detail cracking in railroad rails, and the precipitation of martensitic Fe-Ni-W alloys. A third grouping looks at microstructure-fracture relationships. Coverage of advancements in metal-lographic techniques includes the use of microcomputers, applied techniques of inplace analysis, and use of the Tandem Van de Graff accelerator facility

353

Metal-matrix corrosion studies in Canadian shield granitic groundwaters  

International Nuclear Information System (INIS)

The Canadian Nuclear Fuel Waste Management program is evaluating two basic supported-shell container concepts for used-fuel immobilization. One concept uses a compacted particulate material within the container to support a thin, corrosion-resistant shell. The other concept, called the metal-matrix concept, uses a cast-in-place metal matrix for shell support. This paper describes corrosion studies on the candidate matrix materials, lead, zinc and aluminum-7 wt.% Si (Al-7 wt.% Si), in the temperature range 293 to 423 K and the dissolved oxygen content range 8 to 410 mg/L. Test specimens were analyzed for general and localized corrosion and the corrosion products were identified. The results showed that, unlike lead, zinc and Al-7 wt.% Si are susceptible to localized corrosion. Lead showed only low general corrosion rates of 2 to 83 ?m/a compared with zinc (36 to 15,800 ?m/a) and Al-7 wt.% Si (6 to 209 ?m/a) in the above temperature and oxygen content ranges. Maximum pit depths of about 0.9 mm on Al-7 wt.% Si and 0.6 mm on zinc were observed. These results indicate that, of the candidate matrix metals studied, lead has the greatest potential to retard radionuclide release from used-fuel disposal containers. 10 references, 7 figures, 2 tables

354

Corrosion studies on containment materials for vitrified heat generating waste  

International Nuclear Information System (INIS)

Mean corrosion rates of carbon steels, monitored by Rsub(p) measurements on specimens in on-going long term immersion tests, are presented. True corrosion rates measured on specimens from two dismantled tests after > 2 years exposure were about 25 ?m yr-1 for both cast and forged steel buried in granite at 90 C but only approx. 3 and 7 ?m yr-1 for the same materials, respectively, in bentonite. Extreme value statistical analysis of maximum pit penetrations observed in experimental studies, to compensate for the small area of test specimens compared with a container, indicates that after 1000 years the maximum pit depth could be 200 mm. Overall, tests with ?-radiation on carbon steel specimens immersed in deaerated seawater at 90 C show that there is an acceleration of corrosion rate with continued exposure at the three radiation dose rates used. However in deaerated groundwater at 90 C the general corrosion rate of forged 0.2% carbon steel is -1 at a dose rate of 105 Rads h-1. Threshold stresses for the initiation of stress corrosion cracking in carbon steel parent and weld metal have been estimated. Preliminary experiments have been initiated to investigate the effect of sulphate reducing bacteria on the corrosion of carbon steel buried in bentonite. (author)

355

Microstructure and Corrosion Properties of AlCoCrFeNi High Entropy Alloy Coatings Deposited on AISI 1045 Steel by the Electrospark Process  

Science.gov (United States)

Electrospark deposition (ESD) was employed to clad the AlCoCrFeNi high-entropy alloy (HEA) on AISI 1045 carbon steel. The relationship between the microstructure and corrosion properties of the HEA-coated specimens was studied and compared with that of the copper-molded cast HEA material. Two major microstructural differences were found between the cast HEA material and the HEA coatings. First, the cast material comprises both columnar and equiaxed crystals with a columnar-to-equiaxed transition (CET), whereas the HEA coatings consist of an entirely columnar crystal structure. The CET phenomenon was analyzed based on Hunt's criterion. Second, unlike the cast HEA material, there was no obvious Cr-rich interdendritic segregation and nano-sized precipitate distributed within the dendrites of the HEA coating. With regard to corrosion properties, the corrosion current of the HEA-coated specimen was significantly lower than for the 1045 steel and the cast HEA material. This was attributed to the ESD specimen having a relatively high Cr oxide and Al oxide content at the surface. Moreover, for the ESD specimen, the absence of Cr-rich interdendritic phase and second-phase precipitation resulted in a relatively uniform corrosion attack, which is different from the severe galvanic corrosion attack that occurred in the cast specimen.

Li, Q. H.; Yue, T. M.; Guo, Z. N.; Lin, X.

2013-04-01

356

High temperature failures of heat resistant cast steel; Hochtemperaturschaeden bei hitzebestaendigem Stahlguss  

Energy Technology Data Exchange (ETDEWEB)

Heat resistant cast steel can fail by high temperature, the atmosphere, deposits and mechanical stresses. High temperature corrosion by gas atmospheres can be oxidation, nitriding, carburization, metal dusting, sulphur and chlorine attack. Corrosion by deposits as oil ash or chromates and liquid metals as copper base alloys, lead, tin and zinc leads to a rapid reduction in wall thickness. Besides there are mechanical stresses which lead to failures by stress rupture cracks or thermoshock. The additional effect by material aging should be considered as well. (orig.)

Steinkusch, W. [Pose-Marre Edelstahlwerk GmbH, Erkrath (Germany)

1998-02-01

357

Meningites bacterianas agudas complicações vasculares: vascular complications Bacterial meningitis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Os autores apresentam o estudo de quatro crianças que tiveram arterite como complicação vascular de meningite bacteriana aguda. Apresentam revisão dos mecanismos fisiopatológicos envolvidos nas alterações vasculares que têm trazido reais progressos no entendimento dessas complicações.The authors present the study of four children with arteritis as vascular complication of acute bacterial meningitis. They report pathophysiological mechanisms involved in vascular lesions, and prog...

Moura-ribeiro, Maria Valeriana L.; Rocha, Cristiane M.; Fernandes, Walter L. M.; Guerreiro, Marilisa M.

1993-01-01

358

Erosion-corrosion; Erosionkorrosion  

Energy Technology Data Exchange (ETDEWEB)

A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment 32 refs, 16 figs, tabs

Aghili, B

1999-05-01

359

Slip-Cast Superconductive Parts  

Science.gov (United States)

Complex shapes fabricated without machining. Nonaqueous slip-casting technique used to form complexly shaped parts from high-temperature superconductive materials like YBa(2)Cu(3)O(7-delta). Such parts useful in motors, vibration dampers, and bearings. In process, organic solvent used as liquid medium. Ceramic molds made by lost-wax process used instead of plaster-of-paris molds, used in aqueous slip-casting but impervious to organic solvents and cannot drain away liquid medium. Organic-solvent-based castings do not stick to ceramic molds as they do to plaster molds.

Wise, Stephanie A.; Buckley, John D.; Vasquez, Peter; Buck, Gregory M.; Hicks, Lana P.; Hooker, Matthew W.; Taylor, Theodore D.

1993-01-01

360

Corrosion control. 2. ed.  

International Nuclear Information System (INIS)

The purpose of this text is to train engineers and technologists not just to understand corrosion but to control it. Materials selection, coatings, chemical inhibitors, cathodic and anodic protection, and equipment design are covered in separate chapters. High-temperature oxidation is discussed in the final two chapters ne on oxidation theory and one on controlling oxidation by alloying and with coatings. This book treats corrosion and high-temperature oxidation separately. Corrosion is divided into three groups: (1) chemical dissolution including uniform attack, (2) electrochemical corrosion from either metallurgical or environmental cells, and (3) stress-assisted corrosion. Corrosion is logically grouped according to mechanisms rather than arbitrarily separated into different types of corrosion as if they were unrelated. For those university students and industry personnel who approach corrosion theory very hesitantly, this text will present the electrochemical reactions responsible for corrosion summed up in only five simple half-cell reactions. When these are combined on a polarization diagram, which is also explained in detail, the electrochemical processes become obvious. For those who want a text stripped bare of electrochemical theory, several noted sections can be omitted without loss of continuity. However, the author has presented the material in such a manner that these sections are not beyond the abilities of any high school graduate who is interested in high school graduate who is interested in technology

 
 
 
 
361

Study on decontamination of plutonium contaminated metal surface by cerium (IV) corrosion process  

International Nuclear Information System (INIS)

To acquire optimal corrosion technical parameter, corrosion process experiment was conducted to stainless steel, carbon steel and cast iron. The experiment results showed nitric acid concentration of corrosion solution had stronger effect on oxidation capability and the stronger oxidation capability was acquired when nitric acid concentration of corrosion solution was 2 mol/L. Under 2 mol/L HNO3+ 0.05 mol/L cerium (IV), the corrosion depth of 10.1, 15.2 and 25.4 was obtained by means of 48 h corrosion process to stainless steel, carbon steel and cast iron, respectively. At the same condition, for plutonium contamination ranging from 0.48 Bq/cm2 to 0.68 Bq/cm2 fell to ranging from 0.06 Bq/cm2 to 0.08 Bq/cm2. Based the experimental results, it could be inferred that cerium (IV) corrosion process was a suitable method for decontamination of plutonium contaminated metal surface. (author)

362

Women and Vascular Disease  

Science.gov (United States)

... and stent placement Cancer - bone Cancer - breast Cancer - kidney Cancer - liver Cancer - lung Deep vein thrombosis Endovascular Treatment ... catheters Vertebroplasty Women and vascular disease Women's health Social Media Facebook Twitter (SIRspecialists) YouTube RSS Feeds Radiation ...

363

Compilation of Hanford corrosion studies  

International Nuclear Information System (INIS)

Experimental Hanford corrosion studies are reviewed with the intent of identifying the types and rates of corrosion encountered, surveying the experimental techniques used to gather corrosion data, and indicating how these data contribute to tank failure predictions. The experimental studies in this document can be divided into the following areas: general and pitting corrosion, stress corrosion cracking, corrosivity of solidified high-level waste, and cathodic protection. (U.S.)

364

Digital vascular imaging (DVI)  

International Nuclear Information System (INIS)

Digitization of the video signals from an image intensifier/TV chain, followed by subtraction, contrast enchancement and reconversion to analogue signals, enables high quality angiographic images to be obtained from an intravenous injection of contrast medium. As the examination is basically noninvasive it can be used in outpatients. The possibilities of Digital Vascular Imaging are demonstrated by images obtained from the various vascular regions using a triple-mode 14 in. image intensifier with a Plumbicon. TV tube. (Auth.)

365

Vascular graft infections  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Vascular procedures are rarely complicated by infection, but if prosthetic vascular graft infection (PVGI) occurs, morbidity and mortality are high. Several patient-related, surgery-related and postoperative risk factors are reported, but they are not well validated. PVGI is due to bacterial colonisation of the wound and the underlying prosthetic graft, generally as a result of direct contamination during the operative procedure, mainly from the patient's skin or adjacent bowel. There is no c...

Hasse, Barbara; Husmann, Lars; Zinkernagel, Annelies; Weber, Rainer; Lachat, Mario; Mayer, Dieter

2013-01-01

366

Microvascularization on collared peccary placenta : a microvascular cast atudy in late pregnancy  

DEFF Research Database (Denmark)

The microvascularization of the collared peccary (Tayassu tajacu) placenta was studied by vascular casts and immunolocalization of a-smooth muscle actin and vimentin, to identify the three dimensional organization and vascular flow interrelation in the microvasculature between the maternal and fetal compartments of the placentae. The immunolocalization of vimentin in the vascular endothelium and in the smooth muscle cells of blood vessels showed indented capillaries along the uterine epithelium and the trophoblast at the sides of complementary maternal and fetal microfolds, or rugae. This confers the three-dimensional structure observed in vascular casts. On the maternal side, casts demonstrated uterine folds coated by with primary and secondary ridges, and by areolae dispersed between these ridges. The arteriole runs through the center/middle of ridges, branching at the top into a microvascular network wall in a basket-like fashion. At the base of these baskets venules were formed. On the fetal side, arterioles branched centrally in the fetal rugae into a capillary network in a bulbous form, complementary to the opposite maternal depressions forming the baskets. At the base of the bulbous protrusions, the fetal venules arise. The blood vessel orientation in the materno-fetal interface of the placentae of collared peccaries suggests a blood flow pattern of the type countercurrent to cross current. The same pattern has been reported in domestic swine demonstrating that, even after 38 million years, the Tayassuidae and Suidae families exhibit similar placental morphology, which is here characterized at the microvascular level.

Santos, Tatiana Carlesso; Oliveira, Moacir Franco

2012-01-01

367

Deconstructing the Caste Hegemony: Lambada Oral Literature  

Directory of Open Access Journals (Sweden)

Full Text Available Indian society is very carefully and dexterouslystratified on the basis of castes and sects. This carefulnessand dexterity are used not only to divide the society intothousands of sections but also to protect and preserve thissystem for ages, banning and barring mobility andinteraction between castes. Each caste has a caste lowerthan itself in hierarchy. Even the most downtrodden anddiscriminated against section like “untouchables” are dividedsharply among themselves according to their castes andpractice untouchability against one another. Subservience toone caste and subjugating another caste will put eachcaste’s agenda, position and attitude in tact by making itrigid in its hierarchical behaviour.

Suneetha Rani Karamsi

2010-05-01

368

Casting technique for light metal alloy  

International Nuclear Information System (INIS)

Light metal alloys such as aluminum, magnesium, zinc and etc. can be produced in the various forms by casting technique. The casting technique for aluminum is classified as mold casting either using a sand mold or permanent mold; or both. Aluminum alloys casting are the most versatile of all common foundry alloys and generally have the highest castability ratings. Aluminum is adaptable to many of the commonly used casting methods and can be readily cast in metal molds. This work is attempted to investigate the availability and reliability of casting technique in obtaining of finish product. (Author)

369

Casting Using A Polystyrene Pattern  

Science.gov (United States)

New technique for making metal aircraft models saves significant amount of time and effort in comparison with conventional lost-wax method. Produces inexpensive, effective wind-tunnel models. Metal wind-tunnel model cast by use of polystyrene pattern.

Vasquez, Peter; Guenther, Bengamin; Vranas, Thomas; Veneris, Peter; Joyner, Michael

1993-01-01

370

Virtualisation of casting engineering  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: Fast response to an enquiry, minimization of costs of identification of best-suited process solution, as well as a capacity to tackle new challenges is the shortest description of the requirements posed by the contemporary market of machines and equipment. These, in consequence, called for making use of mathematical models and their solution by means of simulation algorithms.Design/methodology/approach: The notable effectiveness of numerical methods streamlined the production preparation process. Maintaining competitiveness, even more tough because of economic factors, is only possible due to cost-effective operation, high quality and well-timed order completion. These, on the other hand, can be facilitated by a broad application of IT tools aiding production management and preparation.Findings: Integration of systems aiding design processes, systems used for simulating selected elements of technologies, as well as of systems supporting instrumentation manufacturing calls for a need to solve a number of complex problems related to IT, mathematical modelling, logistics and knowledge management. Software packages for a simulation of processes that are indispensable in order to achieve the designed distribution of matter structures and condition are of particular importance.Research limitations/implications: Despite the fact that there is a wide range of software for these purposes available on the market, there is a need to build and integrate into IT systems new purpose-developed solutions customised to technologies applied and non-standard problems.Originality/value: Virtualization of casting engineering

J.S. Suchy

2007-09-01

371

Tunneling corrosion mechanism of the hot forged austenitic stainless steel in highly oxidizing nitric acid  

International Nuclear Information System (INIS)

Austenitic Stainless Steels have been used for reprocessing plants where spent nuclear fuels are dealt with in hot nitric acid. Conventional stainless steels are resistant enough to nitric acid. However, they are prone to localized corrosion when nitric acid becomes highly oxidizing with birth of oxidants such as Ce4+ or Cr6+ ion during the reprocessing. Pitting type corrosion, so-called tunneling or end-grain corrosion occurred on the forgings of 25%-20%-Nb stainless steel (310Nb stainless steel) in such nitric acid solutions because of transpassive corrosion. It has been well known that metal surfaces of steel products casted, forged or rolled are susceptible to the tunneling corrosion in aggressive corrosion media. Nevertheless, neither clear explanations of the mechanism nor definite countermeasures have been proposed yet. This paper describes the mechanism and countermeasures on the tunneling corrosion of stainless steels in nitric acid relevant to spent nuclear fuel reprocessing. The results obtained are as follows: both general and intergranular corrosion occur on austenitic stainless steels in boiling 8N HNO3 with Cr6+ions. Tunneling corrosion is initiated and propagates at the metal surfaces of 310Nb stainless steel forgings along chromium depleted areas vertical to metal flows. The grooves due to the tunneling corrosion are of diameters of 0.5 to 2 mm with a maximum depth of 6mm depending on exposure time and Cr6+ concentration in nitric acid. Tunneling corrosion proceeds by build up of galvanic corrosion cells with Cr depleted parts as anodes and their neighborhoods as cathodes. The Cr depleted parts are formed during solidification of ingots and still retained parallel to the metal flow even after forging. The ESR (Electro Slag Remelting) is one of the useful preventive methods to tunneling corrosion from the view point of steel homogenization

372

Selected properties of new „duplex” cast steel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper selected properties of new „duplex” cast steel are presented. The new cast steel was devised in HYDRO-VACUUM company in Grudzi?dz, where “duplex” cast steel for pump elements is smelted. The goal was to devise a new grade of “duplex” cast steel of better physicochemical properties and cheaper than now applied. It was demonstrated, that there is the possibility of devising the new grade of “duplex” cast steel. It is characterized by higher mechanical properties, ...

Pietrowski, S.; Gumienny, G.; Masalski, M.

2011-01-01

373

Copper alloys in investment casting technology  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents research results in the field of casting technology of copper and copper alloys using the investment casting technology, both from historical as well as modern technology perspective. The analysis of exemplary elements of the old casting moulds is included, as well as the Bronze Age casts. The chemical content of various copper alloys was determined and the application of lost wax method was confirmed in the Bronze Age workshop. At present, investment casting method is use...

Rzadkosz, S.; Zych, J.; Garbacz-klempka, A.; Kranc, M.; Kozana, J.; Pie?kos?, M.; Kolczyk, J.; Jamrozowicz, ?.; Stolarczyk, T.

2015-01-01

374

Manufacturing synthetic cast iron for NPP components  

Energy Technology Data Exchange (ETDEWEB)

The process of producing synthetic cast iron grade SCH30-SCH40 to manufacture cast parts for NPPs with the use of melting in commercial frequency induction furnaces has been developed and introduced. Strict observation of the manufacturing procedure permits to obtain high-quality cast iron with flake graphite for NPP main castings without using expensive modifiers. Cast iron smelted according to the suggested technology is characterized by high strength indices at tension (400 MPa) and bending (540 MPa).

Blozhko, N.K.; Petrov, L.A.; Narkevich, E.A.; Nikitin, L.A.; Kurochkin, V.S.

1984-07-01

375

Low-alloy constructional cast steel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Production of constructional casting competitive for welded structure of high-strength steel first of all required high metallurgical quality of cast steel. Assumptions, methodology and results of investigation which the aim was determination of the most advantageous: configuration and parameters of metallurgical treatments and ways to modify, in aspects of reach the low-alloy cast steel of the highest quality as possible, are presented. A series of low-alloy cast steel melts modeled on cast ...

Bartocha, D.; Kilarski, J.; Suchon?, J.; Baron, C.; Szajnar, J.; Janerka, K.

2011-01-01

376

Geometric aspects of the casting process  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Manufacturing is the process of converting raw materials into useful products. Among the most important manufacturing processes, casting is a commonly used manufacturing process for plastic and metal objects. The industrial casting process consists of two stages. First, liquid is filled into a cavity formed by two cast parts. After the liquid has hardened, one cast part retracts, carrying the object with it. Afterwards, the object is ejected from the retracted cast part. In both retraction an...

Ahn, H. -k

2001-01-01

377

Inoculation of chromium white cast iron  

Directory of Open Access Journals (Sweden)

Full Text Available It has been proved that an addition of boron carbide introduced as an inoculant to the chromium white cast iron changes the structureof castings. Castings after inoculation revealed a different structure with numerous grains. Primary precipitates of chromium carbide also appeared, reducing the mechanical properties of as-cast parts. Properly established heat treatment regime makes chromium iron castings regain their, originally high, mechanical properties.

D. Kopyci?ski

2009-01-01

378

CASTE SYSTEMS IN INDIA: AN OVERVIEW  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The phenomenon of Caste has aroused more controversy than any other aspect of Indian life and thought. Some see India's caste system as the defining feature of Indian culture and some have dismissed it as a colonial artefact. Since the days of the British rule, both historians and anthropologists referred to India as a 'caste society'. Obviously this is an overstatement of the importance of caste. But for many leading personalities, caste was, and is, a real force in India...

Amit Kumar; Lal Das, S. N.

2014-01-01

379

Natural analogues for expansion due to the anaerobic corrosion of ferrous materials  

International Nuclear Information System (INIS)

In Sweden, spent nuclear fuel will be encapsulated in sealed cylindrical canisters, consisting of a cast iron insert and a copper outer container. The canisters will be placed in a deep geologic repository and surrounded by bentonite. If a breach of the outer copper container were to occur the cast iron insert would undergo anaerobic corrosion, forming a magnetite film whose volume would be greater than that of the base metal. In principle there is a possibility that accumulation of iron corrosion product could cause expansion of the copper canister. Anaerobic corrosion rates are very slow, so in the work described in this report reference was made to analogous materials that had been corroding for long periods in natural anoxic aqueous environments. The report considers the types of naturally occurring environments that may give rise to anoxic environments similar to deep geological groundwater and where ferrous materials may be found. Literature information regarding the corrosion of iron archaeological artefacts is summarised and a number of specific archaeological artefacts containing iron and copper corroding in constrained geometries in anoxic natural waters are discussed in detail. No evidence was obtained from natural analogues which would suggest that severe damage is likely to occur to the SKB waste canister design as a result of expansive corrosion of cast iron under repository conditions

380

Natural analogues for expansion due to the anaerobic corrosion of ferrous materials  

Energy Technology Data Exchange (ETDEWEB)

In Sweden, spent nuclear fuel will be encapsulated in sealed cylindrical canisters, consisting of a cast iron insert and a copper outer container. The canisters will be placed in a deep geologic repository and surrounded by bentonite. If a breach of the outer copper container were to occur the cast iron insert would undergo anaerobic corrosion, forming a magnetite film whose volume would be greater than that of the base metal. In principle there is a possibility that accumulation of iron corrosion product could cause expansion of the copper canister. Anaerobic corrosion rates are very slow, so in the work described in this report reference was made to analogous materials that had been corroding for long periods in natural anoxic aqueous environments. The report considers the types of naturally occurring environments that may give rise to anoxic environments similar to deep geological groundwater and where ferrous materials may be found. Literature information regarding the corrosion of iron archaeological artefacts is summarised and a number of specific archaeological artefacts containing iron and copper corroding in constrained geometries in anoxic natural waters are discussed in detail. No evidence was obtained from natural analogues which would suggest that severe damage is likely to occur to the SKB waste canister design as a result of expansive corrosion of cast iron under repository conditions.

Smart, N.R.; Adams, R. [Serco Assurance, Culham Science Centre (United Kingdom)

2006-10-15

 
 
 
 
381

Corrosion resistance of neodymium composite materials reinforced with metal powders  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The goal of the study is to investigate the corrosion resistance of hard magnetic composite materials Nd-Fe-B with 5%, 10% and 15% by weight of iron powder, casting copper alloy with tin CuSn10, steel corrosion-resistant X2CrNiMo17-12-2 and Epidian100 (2.5% by mass as a binder in a humid environment at 40°C and 5% NaCl solution at 35°C and to determine their current-voltage characteristics.Design/methodology/approach: The investigations of corrosion resistance of hard magnetic composite materials in climate chambers were carried out : test 1 (temperature 40°C, relative humidity 93%, duration 96 h, test 2 (temperature 35°C, 5% NaCl solution, duration 6 h. Pitting corrosion were made in an environment of 5% NaCl solution at 35°C.Findings: The results of corrosion tests allows to determinate that the best corrosion show composite materials with addition of 15% of CuSn10 or X2CrNiMo17-12-2.Practical implications: Composite materials Nd-Fe-B – polymer matrix can greatly expand the application possibilities of hard magnetic materials however further examination to obtain materials with improved properties are still needed.Originality/value: Results show corrosion resistance of Nd-Fe-B - polymer matrix composite materials determined by different methods. Results are the base for further investigations of the impact of corrosion environment on the magnetic properties of such composite materials.

M. Dzieko?ska

2012-12-01

382

The influence of carbon and copper on the solidification process of the ferritic-austenitic cast steel  

Directory of Open Access Journals (Sweden)

Full Text Available Technological problems which occur during the production of castings made of ferritic-austenitic (duplex cast steel have caused that this most modern material among corrosion-resistant cast steels is seldom produced in Poland. The main reason of arising problems is the necessity of achieving a very low carbon content (Cmax = 0.03%, according to PN-EN 10283:2004 and the occurring of hot cracking. It is impossible for our domestic foundries to achieve such a low carbon content, because it demands for out-of-furnace treatment. It should be mentioned that the standards developed by international cast steel producers admit also cast steel grades with higher carbon content than the PN-EN 10283:2004 Standard. The so far produced in Poland massive castings have exhibited higher (~ 0,05‚0,12 carbon content, but also the significant hot cracking susceptibility. Is the increased carbon content along with about 3% copper addition, which lowers the temperature of the end of solidification process, the reason of hot cracking of produced castings? The paper presents the results of investigation performed by DDTA and ThermoCalc analyses, as well as by microstructural examination for duplex cast iron with varying carbon content.

J. Stradomska

2009-07-01

383

Operational experiences of corrosion in seawater-cooled heat exchanges in Finnish and Swedish power plants  

International Nuclear Information System (INIS)

A survey has been made of the corrosion behaviour of seawater cooled heat exchangers in Finnish and Swedish power plants. Of the tube materials only titanium and a few high alloy stainless steels have been entirely corrosion resistant during 2-3 years of operation. Aluminium brass has been attacked by erosion corrosion and pitting, and CuNi 70/30 by erosion corrosion. The failure rate (FR) for aluminium brass is normally below 0,1, which is less than half of that reported from American power stations cooled with pure seawater. The survey shows that FeSO4 dosage and cathodic protection with impressed current from Fe anodes reduces the corrosion of aluminium brass. On the other hand no conclusions can be drawn about the effect of sponge ball cleaning or chlorination. Tube plates of Muntz metal, Naval Brass and type 316 clad steel have exhibited very marginal corrosion problems. In the latter, however, the corrosion in the tube to tube plate crevices has increased after changing from copper alloy to titanium tubes. In water boxes of carbon steel and cast iron with organic coating the corrosion problems have been small. Stainless steel type 304 has been attacked by crevice corrosion, but not the high alloy type 904 L

384

Fireside corrosion of superheater alloys for advanced-cycle steam plants: Final report  

Energy Technology Data Exchange (ETDEWEB)

Coal ash corrosion data are needed to solve existing problems and to identify candidate materials for new improved coal-fired power plants. This report addresses the question of coal-ash corrosion data in the following areas: Laboratory corrosion test data on higher strength tube materials and cast support materials; discussion and interpretation of results of these data; discussion of methods for avoiding corrosion, including the concept of operating above the bell-shaped curve; and review of recent fireside corrosion studies and plant experience. Recent US and overseas laboratory tests using synthetic ash show severe corrosion losses for high-temperature alloys such as austenitic stainless steels containing molybdenum and Fe-Ni-Cr alloys. This corrosion loss occurs in the temperature range between 677 and 718/sup 0/C (1250 and 1325/sup 0/F). The laboratory tests performed during this program have shown that some modified stainless steels such as the Foster Wheeler-developed Alloy 4C and Sandvik 253 MA will provide substantially improved resistance to corrosion, which will be adequate, in most cases. For most steels and high alloys, the maximum corrosion rates were above 704/sup 0/C (1300/sup 0/F), indicating that future designs for plants operating in this region must incorporate additional material development. Alternative materials and special alloys containing silicon additions appear promising. 28 refs., 34 figs., 20 tabs.

Rehn, I.M.

1987-05-01

385

STUDIES ON CASTING FLUIDITY AND POROSITY ON SOLIDIFICATION OF ALUMINIUM SILICON EUTECTIC ALLOY  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aluminium Silicon eutectic alloy called LM-6 contains 10 to 13% of Silicon by weight. It has good casting properties such as high strength to weight ratio and excellent corrosion resistance. So this alloy finds application in automobile, aircraft and marine industries. In this project work, modifier is added to improve the mechanical properties of LM-6 alloy such as tensile strength, fluidity and also the variation in porosity distribution. Modification is a chemical treat...

Anju Ramesh; Saleem, N.; Najarajan, N. M.

2014-01-01

386

Microstructure of AE44 magnesium alloy before and after hot-chamber die casting  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: AE44 magnesium alloy allows attractive high temperature mechanical properties, as well as diecastabilityand good corrosion resistance. It contains magnesium, aluminum, cerium and lanthanum. Typically,it is used in automotive industry for structural components working at elevated temperature (150÷175°C). Theaim of this paper is to present the results of investigations on the microstructure of the AE44 magnesium alloybefore and after hot chamber die casting.Design/methodology/approac...

Kie?bus, A.

2007-01-01

387

Corrosion in power engineering  

International Nuclear Information System (INIS)

The proceedings contain full texts of 28 contributions, out of which 3 fall within the INIS subject scope. These are concerned with general corrosion problems in nuclear power industry and with corrosion effects of decontamination solutions on the structural materials of primary circuits of nuclear power plants. (Z.M.)

388

Archaeological analogs and corrosion  

International Nuclear Information System (INIS)

In the framework of the high level and long life radioactive wastes disposal deep underground, the ANDRA built a research program on the material corrosion. In particular they aim to design containers for a very long time storage. Laboratory experiments are in progress and can be completed by the analysis of metallic archaeological objects and their corrosion after hundred years. (A.L.B.)

389

Thermogalvanic corrosion revisited  

Energy Technology Data Exchange (ETDEWEB)

Thermogalvanic corrosion is a phenomenon that seems to be overlooked in current equipment designs and failure analyses. The mechanisms involving reactions between zones of a metal component as a function of temperature differences are explained. The potentials are functions of the temperature and dynamics of the system involved. Because the reactions are small, identification of the corrosion effect requires continual observation.

Hamner, N.E. (Technedit, Katy, TX (United States))

1993-06-01

390

Erosion and erosion-corrosion  

International Nuclear Information System (INIS)

It is very difficult to interpret the technical term of erosion-corrosion' which is sometimes encountered in piping systems of power plants, because of complicated mechanisms and several confusing definitions of erosion-corrosion phenomena. 'FAC (flow accelerated corrosion)' is recently introduced as wall thinning of materials in power plant systems, as a representative of 'erosion-corrosion'. FAC is, however, not necessarily well understood and compared with erosion-corrosion. This paper describes firstly the origin, definition and fundamental understandings of erosion and erosion-corrosion, in order to reconsider and reconfirm the phenomena of erosion, erosion-corrosion and FAC. Next, typical mapping of erosion, corrosion, erosion-corrosion and FAC are introduced in flow velocity and environmental corrosiveness axes. The concept of damage rate in erosion-corrosion is finally discussed, connecting dissolution rate, mass transfer of metal ions in a metal oxide film and film growth. (author)

391

Crude unit corrosion and corrosion control  

Energy Technology Data Exchange (ETDEWEB)

In the petroleum refining process, the Crude Unit is the initial stage of distillation of the crude oil into useable fractions, either as end products or feed to downstream units. The major pieces of equipment found on units will vary depending on factors such as the assay of the design crude, the age of the refinery, and other downstream units. The unit discussed in this paper has all of the major pieces of equipment found on crude units including double desalting, a preflash section, an atmospheric section, a vacuum section, and a stabilization section. This paper reviews fundamental corrosion issues concerning the Crude Unit process. It is, in concise form, a description of the process and major equipment found in the Crude Unit; types of corrosion and where they occur; corrosion monitoring and inspection advice; and a list of related references for further reading. 12 refs., 1 fig.

Bagdasarian, A. [Chevron Research and Technology Co., Richmond, CA (United States); Feather, J.; Hull, B.; Stephenson, R.; Strong, R.

1996-08-01

392

Long-term corrosion behavior of cathodicly protected cask materials  

International Nuclear Information System (INIS)

The concept of a canister based on the principle of cathodic protection has been introduced. The main points for this concept are: nonself-shielding canisters require a radiation protection jacket during the operational stage of the repository; cost-efficient material for radiation protection is nodular cast iron; and multilayered canister consisting of materials which become successively more noble towards the inner shells has been found to be too large and too heavy for a repository. This problem has been overcome now by a new and cost-efficient production method. This is accomplished by immersing a tube made of stainless steel in molten GGG 40.3 at a defined temperature and letting them cool together. Dimensions and weight now meet the requirements of the repository. In case of an accident, that is intrusion of brine into the repository and contact with the canister, corrosion will start uniformly at the outer cast iron package. This package is sufficiently designed not to be used up in a projected term of 500 years. If, nonetheless, the cast iron jacket should rupture by means of corrosion or mechanical damage, a shortcircuit cell will form with the cast iron being the anode and the stainless steel acting as the cathode. The testing of welded large-scale integral structures, which can be regarded as mock-ups of a canister section, is in progress since March 1984 to demonstrate the feasibility of this container concept. Two such bodies are immersed in brine at 100 such bodies are immersed in brine at 100 degree C. Examinations with the very sensitive liquid penetration test fluorescent proved both bodies to be free of incipient cracks or local corrosion in the area of the weld seams

393

Fluxless recycling of die-cast AZ91 magnesium alloy scrap  

Energy Technology Data Exchange (ETDEWEB)

Magnesium die-casting has experienced dramatic growth over the past decade and the recycling of magnesium scrap has become increasingly important due to the generation of substantial quantities of scrap in the die-casting process. Magnesium is a readily recyclable material and the recycling of magnesium scrap is crucial in making magnesium more competitive. The main concern associated with using the secondary magnesium is the high level of Fe content and oxide inclusions that are detrimental to the corrosion and mechanical properties of the secondary alloy. In this study, the die-cast specimens were produced using the recycled class 1 scrap which is refined by means of Ar bubbling and Mn addition without using refining fluxes, and their mechanical properties and corrosion characteristics were investigated. The results showed that the tensile properties of the secondary AZ91 alloy were equivalent to those of the primary magnesium alloy after appropriate treatments. The corrosion resistance of the recycled magnesium was also found to increase by Ar bubbling and Mn addition. (orig.)

Jung, H.C.; Lee, Y.C.; Shin, K.S. [School of Materials Science and Engineering, Research Inst. of Advanced Materials, Seoul National Univ. (Korea)

2005-07-01

394

Titan Casts Revealing Shadow  

Science.gov (United States)

A rare celestial event was captured by NASA's Chandra X-ray Observatory as Titan -- Saturn's largest moon and the only moon in the Solar System with a thick atmosphere -- crossed in front of the X-ray bright Crab Nebula. The X-ray shadow cast by Titan allowed astronomers to make the first X-ray measurement of the extent of its atmosphere. On January 5, 2003, Titan transited the Crab Nebula, the remnant of a supernova explosion that was observed to occur in the year 1054. Although Saturn and Titan pass within a few degrees of the Crab Nebula every 30 years, they rarely pass directly in front of it. "This may have been the first transit of the Crab Nebula by Titan since the birth of the Crab Nebula," said Koji Mori of Pennsylvania State University in University Park, and lead author on an Astrophysical Journal paper describing these results. "The next similar conjunction will take place in the year 2267, so this was truly a once in a lifetime event." Animation of Titan's Shadow on Crab Nebula Animation of Titan's Shadow on Crab Nebula Chandra's observation revealed that the diameter of the X-ray shadow cast by Titan was larger than the diameter of its solid surface. The difference in diameters gives a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere. The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. "Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may account for some of this atmospheric expansion," said Hiroshi Tsunemi of Osaka University in Japan, one of the coauthors on the paper. The X-ray brightness and extent of the Crab Nebula made it possible to study the tiny X-ray shadow cast by Titan during its transit. By using Chandra to precisely track Titan's position, astronomers were able to measure a shadow one arcsecond in diameter, which corresponds to the size of a dime as viewed from about two and a half miles. Illustration of Crab, Titan's Shadow and Chandra Illustration of Crab, Titan's Shadow and Chandra Unlike almost all of Chandra's images which are made by focusing X-ray emission from cosmic sources, Titan's X-ray shadow image was produced in a manner similar to a medical X-ray. That is, an X-ray source (the Crab Nebula) is used to make a shadow image (Titan and its atmosphere) that is recorded on film (Chandra's ACIS detector). Titan's atmosphere, which is about 95% nitrogen and 5% methane, has a pressure near the surface that is one and a half times the Earth's sea level pressure. Voyager I spacecraft measured the structure of Titan's atmosphere at heights below about 300 miles (500 kilometers), and above 600 miles (1000 kilometers). Until the Chandra observations, however, no measurements existed at heights in the range between 300 and 600 miles. Understanding the extent of Titan's atmosphere is important for the planners of the Cassini-Huygens mission. The Cassini-Huygens spacecraft will reach Saturn in July of this year to begin a four-year tour of Saturn, its rings and its moons. The tour will include close flybys of Titan that will take Cassini as close as 600 miles, and the launching of the Huygens probe that will land on Titan's surface. Chandra's X-ray Shadow of Titan Chandra's X-ray Shadow of Titan "If Titan's atmosphere has really expanded, the trajectory may have to be changed." said Tsunemi. The paper on these results has been accepted and is expected to appear in a June 2004 issue of The Astrophysical Journal. Other members of the research team were Haroyoski Katayama (Osaka University), David Burrows and Gordon Garmine (Penn State University), and Albert Metzger (JPL). Chandra observed Titan from 9:04 to 18:46 UT on January 5, 2003, using its Advanced CCD Imaging Spectrometer instrument. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the Office of Space Science, NASA Headquarters,

2004-05-01

395

Monitoring corrosion rates and localised corrosion in low conductivity water  

DEFF Research Database (Denmark)

Monitoring of low corrosion rates and localised corrosion in a media with low conductivity is a challenge. In municipal district heating, quality control may be improved by implementing on-line corrosion monitoring if a suitable technique can be identified to measure both uniform and localised corrosion. Electrochemical techniques (LPR, EIS, crevice corrosion current) as well as direct measurement techniques (high-sensitive electrical resistance, weight loss) have been applied in operating plants. Changes in the corrosion processes are best monitored in non-aggressive, low conductivity media with sensitive electrical resistance technique and crevice corrosion current measurements.

Hilbert, Lisbeth Rischel

2006-01-01

396

Vascular nevi in children  

Directory of Open Access Journals (Sweden)

Full Text Available Background: Vascular nevi are cutaneous anomalies of angiogenesis and vasculogenesis resulting in various different clinical presentations. Aim: The purpose of our descriptive study was to observe the various types of vascular nevi in children and their features. Methods: A total of 4256 pediatric cases attending the dermatology OPD during the study period from August 2002 to August 2004 were screened for vascular nevi. Results: Out of these, 19 children (0.44% had vascular nevi-17 hemangiomas of infancy (HOIs and 2 port-wine stains. The mean age of the affected children was 1.3 years (ranging from 2.5 months to 8 years. There were 13 girls and 6 boys. Seventeen (89.5% patients had progressing lesions and two (10.5% had non-involuting ones. A solitary lesion was seen in ten (52.6% cases and two to five lesions were present in five (26.3% cases. The nevi were distributed over multiple sites in seven (36.8% cases, the head and neck in six (31.6% cases, the chest and lower limb in two (10.5% cases each, and the upper limbs and genitalia in one (5.3% case each. Among the hemangiomas of infancy, 15 (88.2% cases of superficial type and 2 (11.8% cases of deep type were seen. The cutaneous complications included ulceration in four cases and infection in one. Conclusions: HOIs were the most common vascular nevi of childhood.

Senthilkumar M

2006-01-01

397

Reliability and Sensitivity Analysis of Cast Iron Water Pipes for Agricultural Food Irrigation  

Directory of Open Access Journals (Sweden)

Full Text Available This study aims to investigate the reliability and sensitivity of cast iron water pipes for agricultural food irrigation. The Monte Carlo simulation method is used for fracture assessment and reliability analysis of cast iron pipes for agricultural food irrigation. Fracture toughness is considered as a limit state function for corrosion affected cast iron pipes. Then the influence of failure mode on the probability of pipe failure has been discussed. Sensitivity analysis also is carried out to show the effect of changing basic parameters on the reliability and life time of the pipe. The analysis results show that the applied methodology can consider different random variables for estimating of life time of the pipe and it can also provide scientific guidance for rehabilitation and maintenance plans for agricultural food irrigation. In addition, the results of the failure and reliability analysis in this study can be useful for designing of more reliable new pipeline systems for agricultural food irrigation.

Yanling Ni

2014-07-01

398

Aluminide protective coatings on high–temperature creep resistant cast steel  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the results of research on aluminide protective coatings manufactured on high–temperature creep resistant cast steel. The main purpose of these coatings is protection against the high temperature corrosion, especially at high carburizing potential atmosphere. Coatings were obtained on cast steel type G–XNiCrSi36–18 with the following methods: pack cementation, paste method, cast method and slurry cementation. The phase composition, thickness and morphology of coatings were determined. Coatings capacity of carbon diffusion inhibition and thermal shocks resistance of coatings were determined with different methods. It was found, that all of the coatings reduce carbon diffusion in different degree and all coatings liable to degradation in consequence cracking and oxidation. Coating life time is mainly dependent on morphology, phase composition and service condition (thermal shocks first of all.

J. Kubicki

2009-10-01

399

Naphthenic corrosion resistance, mechanical properties and microstructure evolution of experimental Cr-Mo steels with high Mo content  

Digital Repository Infrastructure Vision for European Research (DRIVER)

One method to face the effects of naphthenic acid corrosion in petroleun refining plants is to use alloys with good resistance to this kind of corrosion. For this purpose, molybdenum additions to chromium containing steels are specially recommended. In this work, experimental Fe-9Cr-xMo (x = 5, 7 and 9 wt. (%)) ingots were cast, forged and hot rolled before being tested in a naphthenic acid environment. Evolution of the mechanical properties with composition is presented. The precipitation an...

Lorena Braga Moura; Rodrigo Freitas Guimarães; Hamilton Ferreira Gomes de Abreu; Hélio Cordeiro de Miranda; Sérgio Souto Maior Tavares1

2012-01-01

400

Monitoring corrosion rates and localised corrosion in low conductivity water  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Monitoring of low corrosion rates and localised corrosion in a media with low conductivity is a challenge. In municipal district heating, quality control may be improved by implementing on-line corrosion monitoring if a suitable technique can be identified to measure both uniform and localised corrosion. Electrochemical techniques (LPR, EIS, crevice corrosion current) as well as direct measurement techniques (high-sensitive electrical resistance, weight loss) have been applied in operating...

Hilbert, Lisbeth Rischel

2007-01-01

 
 
 
 
401

Fillability of Thin-Wall Steel Castings  

Energy Technology Data Exchange (ETDEWEB)

The use of steel components is being challenged by lighter nonferrous or cast iron components. The development of techniques for enhancing and ensuring the filability of thin-wall mold cavities is most critical for thinner wall cast steel production. The purpose of this research was to develop thin-wall casting techniques that can be used to reliably produce thin-wall castings from traditional gravity poured sand casting processes. The focus of the research was to enhance the filling behavior to prevent misrunds. Experiments were conducted to investigate the influence of various foundry variables on the filling of thin section steel castings. These variables include casting design, heat transfer, gating design, and metal fluidity. Wall thickness and pouring temperature have the greatest effect on casting fill. As wall thickness increases the volume to surface area of the casting increases, which increases the solidification time, allowing the metal to flow further in thicker sect ions. Pouring time is another significant variable affecting casting fill. Increases or decreases of 20% in the pouring time were found to have a significant effect on the filling of thin-wall production castings. Gating variables, including venting, pouring head height, and mold tilting also significantly affected thin-wall casting fill. Filters offer less turbulent, steadier flow, which is appropriate for thicker castings, but they do not enhance thin-wall casting fill.

Robert C. Voigt; Joseph Bertoletti; Andrew Kaley; Sandi Ricotta; Travis Sunday

2002-07-30

402

Corrosion Failures in Marine Environment  

Directory of Open Access Journals (Sweden)

Full Text Available This paper gives a brief description of typical marine environments and the most common form of corrosion of materials used in this environment. Some typical case histories of failures pertaining to pitting,