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Sample records for vascular corrosion casts

  1. The vascular anatomy of the rat superficial epigastric flap by vascular corrosion casting and technical refinement for the study of choke vessels in cadaveric flap models.

    Science.gov (United States)

    Cotrufo, Stefano; Dabernig, Joerg; Russell, David; Payne, Anthony; Hart, Andrew

    2010-01-01

    Accurate depiction of cutaneous vascular microanatomy is of relevance to plastic surgical flap research, and to descriptive anatomy. Yet current techniques have not permitted full visualization of the subdermal plexus, or potential angiosomal connections. Nor has endothelial visualization been facilitated. Vascular corrosion casting techniques are promising in that regard, and were applied in an extended lateral thoracoabdominal suprafascial adipocutaneous flap in the rat (based on the superficial epigastric bundle). Technical refinements for application to further study of human cadaveric flap models are presented. The intraflap vascular branching pattern of the superficial epigastric artery is described, with filling of the lateral thoracic, intercostals, and iliolumbar angiosomes found when coagulation of vessels at the periphery was delayed until after clearance. The vascular casting protocol presented is an effective and promising tool for the study of macro- and microvascular anatomy. PMID:20010416

  2. Microvascularization of the interhyoid muscle in larval Xenopus laevis (Daudin): Scanning electron microscopy of vascular corrosion casts and correlative light microscopy.

    Science.gov (United States)

    Rattey, J; Lametschwandtner, A

    2011-03-01

    The interhyoid muscle in tadpoles of Xenopus laevis (Daudin) is an important part of the buccal pump, a functional unit that provides unidirectional flow of water through mouth and pharynx. In anuran tadpoles, this flow is crucial in both respiration (gas exchange) and food intake (ingestion). The microvascular anatomy of the interhyoid muscles of 43 tadpoles of X. laevis from developmental stages 49-60 was examined by scanning electron microscopy of vascular corrosion casts and correlative light microscopy of paraplast embedded Goldner stained serial tissue sections. Analysis of vascular corrosion casts of the interhyoid muscle showed that several descending branches of external carotid arteries supplied the interhyoid muscle. Arteries splitted into many arterioles at the dorsal surface of the interhyoid muscle and formed sheaths of longitudinally orientated capillaries around muscle fibers. Postcapillary vessels formed perpendicularly orientated arrays of collecting venules (mean diameter: 15.6 ?m), which drained the interhyoid muscle from the ventral surface into external jugular veins. Cast analyses revealed sprouting angiogenesis at the capillary level and nonsprouting angiogenesis at distal domains of the venous system. Both means of angiogenesis that persisted throughout the developmental periods examined are thought to represent a superposition of concurrent developmental and physiological processes. The dense microvascular bed of the interhyoid muscle reflects its high demand for supply with oxygen and nutrients. PMID:21312231

  3. Microvascular anatomy of the large intestine in adult Xenopus laevis: scanning electron microscopy of vascular corrosion casts and correlative light microscopy.

    Science.gov (United States)

    Lametschwandtner, A; Bartel, H; Lametschwandtner, U; Tholo, S; Minnich, B

    2010-01-01

    The microvascular anatomy of the large intestine of the adult South African Clawed Toad, Xenopus laevis (Daudin), was studied by scanning electron microscopy (SEM) of vascular corrosion casts (VCCs) and correlative light microscopy. Observations showed the large intestine to be supplied by the haemorrhoidal artery and the posterior mesenteric artery and drain via the posterior haemorrhoidal vein into either the left or right posterior abdominal vein. Both arteries and veins showed a bipinnate supply/draining pattern with branches running circumferentially. Vessels embraced the gut wall while arteries and veins in most cases alternated along the gut length. Many short terminal arterioles arose from the circumferential arteries at almost acute angles and capillarized after a short distance. Capillary lengths were short and continued into numerous postcapillary venules which merged either in a leaf vein-like formation or in a rosette-like formation with up to four draining sites per supplying arteriole. The microvasculature was found to be well adapted 1) to sustain blood flow under different amounts of feces in the gut and 2) to provide optimal conditions for the resorption of water and salts from the gut lumen into the blood vascular system by the high number of venules and their conspiciouos rosette-like and leaf vein-like patterns. PMID:21471667

  4. The microvascular anatomy of the trachea in adult Xenopus laevis Daudin (Lissamphibia; Anura): scanning electron microscopy of vascular corrosion casts and correlative light microscopy.

    Science.gov (United States)

    Tangphokhanon, Wasan; Lametschwandtner, Alois

    2012-06-01

    Studies on the amphibian respiratory tract microvascular anatomy are few and contradictory. Using scanning electron microscopy of vascular corrosion casts, correlative light microscopy of paraplast-embedded Goldner-stained serial tissue sections, and three-dimensional morphometry, we studied the topographic microvascular anatomy in the trachea of the adult South African Clawed Toad, Xenopus laevis Daudin. Histomorphology showed that the cartilaginous portion of the trachea contained irregularly shaped hyaline cartilage plates in its cranial and caudal portions and C-shaped hyaline cartilage rings in the middle portion. Tracheal cartilages formed large continuous plates on the ventral circumference, numerous small discontinuous plates on the dorsal circumference, and large vertical plates on the caudolateral circumference. The muscular portion of the trachea consisted of bands of smooth muscle that joined the free ends of cartilage plates. The supply of the trachea was via pulmonal artery-tracheobronchial trunk artery-tracheobronchial artery-tracheal artery. The subepithelial capillary network consisted of rectangular meshes which are in the area of the tracheal cartilages located between the cartilages and the respiratory epithelium. Small tracheal veins merged into a single tracheal vein that emptied into the pulmonary vein. Because of its dense subepithelial capillary network and its drainage into the pulmonal vein, the trachea could actively take part in respiration. PMID:22539457

  5. Corrosion of cast and non equilibrium magnesium alloys

    International Nuclear Information System (INIS)

    Due to their low density, magnesium alloys arc very promising as regards applications in the automotive or aeronautical industry. Their corrosion resistance has however to be increased, particularly for cast alloys which are very often two-phased and thus suffer from internal galvanic corrosion. With use of sputtering methods of elaboration, homogeneous magnesium alloys containing far from equilibrium Al, Zr or valve metals contents can be prepared. Corrosion data for Mg-Al-Zn-Sn alloys and MgZr alloys obtained by sputtering, have been determined and compared to those of cast and thixocast AZ91 alloy. Electrochemical tests have evidenced a significantly better behaviour of non equilibrium alloys which, thanks to XPS measurements, could be correlated to the composition of the superficial oxide scale formed on these alloys. (author)

  6. Stress Corrosion Cracking Behavior of Cast Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Teysseyre, Sebastien [University of Michigan; Busby, Jeremy T [ORNL; Was, Gary [University of Michigan

    2009-01-01

    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 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.

  7. 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)

  8. 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

  9. Galvanic corrosion of copper-cast iron couples

    International Nuclear Information System (INIS)

    To ensure the safe encapsulation of spent nuclear fuel rods for geological disposal, SKB are considering using the Copper-Cast 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 would enter the annulus between the inner and outer canister and at points of contact between the two metals there would be the possibility of galvanic interactions. Although this subject has been considered previously from both a theoretical standpoint and by experimental investigations there was a need for further experimental studies in support of information provided by SKB to the Swedish regulators (SKI). In the work reported here 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 porewaters at 30 deg C and 50 deg C, under aerated and deaerated conditions. Tests were also carried out in a 30 wt% bentonite slurry made up in artificial groundwater. The potential of the couples and the currents passing between the coupled electrodes were monitored for several months. The effect of growing an oxide film on the surface of the cast iron prior to coupling it with copper was investigated. In addition, some 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 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 ?m/year for iron were observed after deaeration, but the corrosion rates were near 100 ?m/year for the cast iron at 50 deg C in the presence of oxygen. There was evidence of temporary polarity reversal at very low levels of current (i.e. the copper became the anode). The galvanic corrosion rates of iron coupled to copper at low groundwater oxygen concentrations were close to the values measured for anaerobic corrosion rates of uncoupled iron. Under deaerated conditions a black film was formed on the surface of the cast iron, which was consistent with the formation of magnetite. The electrochemical potentials of the cast iron-copper couples in deaerated conditions were in the thermodynamically stable regions for magnetite and metallic copper. The galvanic currents under deaerated conditions were higher at 50 deg C than at 30 deg C, by a factor of up to 10. This can be attributed to an increase in the exchange current density for the water reduction reaction on the copper cathode and to an increase in the rate of diffusion processes in the oxide film on cast iron. There was some evidence for an increase in the galvanic corrosion rate in the presence of bentonite slurry compared to fully aqueous artificial groundwaters. Pre-grown corrosion films on cast iron did not have a significant effect on subsequent measured galvanic corrosion rates when coupled to copper in deaerated conditions. None of the MCA specimens exhibited any signs of galvanically enhanced crevice corrosion under deaerated conditions. In terms of application of the results to the evolution of the environment within the annulus of the canister the following scenario is envisaged. If water penetrates the annulus through a hole in the outer copper container a galvanic couple will be set up between the copper and the cast iron insert. The current passing between the copper and the cast iron will be concentrated at the contact points. If any residual air is present in the annulus the corrosion rate of the cast iron will be enhanced (i.e. the iron will be the anode and copper the cathode). In the absence of oxygen in the annulus, as a result of oxygen consu

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

    OpenAIRE

    Li, Wei; LIU Jun-quan; TU Xiao-hui3

    2007-01-01

    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...

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

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    LI Wei

    2007-02-01

    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.

  12. Erosion-corrosion behavior of austenitic cast iron in an acidic slurry medium

    Science.gov (United States)

    Yang, Ke; Sun, Lan; Liu, Yu-zhen; Fan, Hong-yuan

    2015-06-01

    A series of austenitic cast iron samples with different compositions were cast and a part of nickel in the samples was replaced by manganese for economic reason. Erosion-corrosion tests were conducted under 2wt% sulfuric acid and 15wt% quartz sand. The results show that the matrix of cast irons remains austenite after a portion of nickel is replaced with manganese. (Fe,Cr)3C is a common phase in the cast irons, and nickel is the main alloying element in high-nickel cast iron; whereas, (Fe,Mn)3C is observed with the increased manganese content in low-nickel cast iron. Under erosion-corrosion tests, the weight-loss rates of the cast irons increase with increasing time. Wear plays a more important role than corrosion in determining the weight loss. It is indicated that the processes of weight loss for the cast irons with high and low nickel contents are different. The erosion resistance of the cast iron containing 7.29wt% nickel and 6.94wt% manganese is equivalent to that of the cast iron containing 13.29wt% nickel.

  13. Assessing the effect of copper additions on the corrosion behaviour of grey cast iron

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    Saliu Ojo SEIDU

    2015-05-01

    Full Text Available In this research work, the effect of copper additions on the corrosion behaviour of grey cast iron in 3.5 wt% NaCl, 0.3M H2SO4, and 0.1M NaOH respectively was investigated. Grey cast iron samples containing 3.0%, 2.5%, 2.0%, and 1.5% weight percent of copper were produced. The corrosion behaviour of the grey cast iron samples produced were assessed using mass loss and corrosion rate measurements according to America Society for Testing and Materials standard (ASTM procedures in salt water, basic, and acidic environments. The results reveal that the samples containing 2.0% and 1.5% weight percent of copper show an excellent corrosion resistance while samples containing 3.0% and 2.5% weight percent of copper show good corrosion behaviour all in salt water and basic environments but poorly in acidic environment.

  14. Accelerated corrosion of steel in dry-cast reinforced concrete pipes after initiation

    Science.gov (United States)

    Weber, Brian William

    Instrumented dry-cast reinforced concrete pipe (DC-RCP) specimens in which corrosion of the reinforcing steel had initiated were selected to accelerate the corrosion. Type C and type F DC-RCP were used. An anodic current density of various magnitudes (0.5 muA/cm2, 1 muA/cm2 and 2.5 muA/cm2) was applied during the corrosion propagation stage. The specimens were placed in high humidity and selected specimens were later covered with wet sand. Selected specimens were terminated for visual examination and gravimetric analysis. Typically, the reinforcement potentials during the accelerated corrosion period were more negative for F specimens compared to C specimens. The C specimens experienced ~2x more corrosion than the F specimens. The accumulated corrosion products did not cause cracks. A method was developed that allows for modest corrosion acceleration during the corrosion propagation stage of DC-RCP.

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

    Science.gov (United States)

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

    2014-12-01

    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

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

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    B. Kalandyk

    2013-01-01

    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.

  17. 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

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

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    Brajendra Nath Tripathi

    1965-01-01

    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.

  19. Expansion due to anaerobic corrosion of steel and cast iron: Experimental and natural analogue studies

    International Nuclear Information System (INIS)

    An apparatus was constructed to measure the expansion caused by the anaerobic corrosion of steel and cast iron whilst under representative compressive loads. The detection of hydrogen and the identification of magnetite on the surface of the specimens demonstrated the occurrence of anaerobic corrosion, but no expansion was observed after over two years' exposure, suggesting that the corrosion product is too soft and deformable to cause jacking of the walls of canisters used for encapsulating spent nuclear fuel. The use of natural analogues to examine the potential for expansion caused by anaerobic corrosion in confined spaces over long time periods is discussed. (authors)

  20. 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

  1. Corrosion Behavior of Cast Iron in Freely Aerated Stagnant Arabian Gulf Seawater

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    El-Sayed M. Sherif

    2015-04-01

    Full Text Available In this work, the results obtained from studying the corrosion of cast iron in freely aerated stagnant Arabian Gulf seawater (AGS at room temperature were reported. The study was carried out using weight-loss (WL, cyclic potentiodynamic polarization (CPP, open-circuit potential (OCP, and electrochemical impedance spectroscopy (EIS measurements and complemented by scanning electron microscopy (SEM and energy dispersive X-ray (EDX investigations. WL experiments between two and 10 days’ immersion in the test electrolyte indicated that the weight-loss the cast iron increases with increasing the time of immersion. CPP measurements after 1 h and 24 h exposure period showed that the increase of time decreases the corrosion via decreasing the anodic and cathodic currents, as well as decreasing the corrosion current and corrosion rate and increasing the polarization resistance of the cast iron. EIS data confirmed the ones obtained by WL and CPP that the increase of immersion time decreases the corrosion of cast iron by increasing its polarization resistance.

  2. 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

  3. 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

  4. Corrosion behaviour of investment cast and friction stir processed Ti-6Al-4V

    International Nuclear Information System (INIS)

    The corrosion behaviour of investment cast and friction stir (FS) processed Ti-6Al-4V alloy was studied in HCl solution. FS processing was performed with the peak temperatures both above and below the ? transus. All of the samples exhibited active-passive transitions in deaerated 5% HCl at room temperature, but the ? FS processed samples exhibited superior corrosion behaviour. The corrosion morphology after immersion in 20% HCl was rationalized on the basis of a difference in partitioning of the alloying elements, which controls the composition of the ? and ? phases.

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

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Xiu; Hu, Shubing, E-mail: hushubing@163.com; Song, Wulin; Xiong, Xuesong

    2013-12-01

    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.

  6. 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.

  7. Study on the hot corrosion behavior of a cast Ni-base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.; Guo, J.T.; Zhang, J.; Yuan, C.; Zhou, L.Z.; Hu, Z.Q. [Chinese Academy of Sciences, Shenyang (China). Inst. of Metal Research

    2010-07-01

    Hot corrosion behavior of Nickel-base cast superalloy K447 in 90% Na{sub 2}SO{sub 4} + 10% NaCl melting salt at 850 C and 900 C was studied. The hot corrosion kinetic of the alloy follows parabolic rate law under the experimental conditions. The external layer is mainly Cr{sub 2}O{sub 3} scale which is protective to the alloy, the intermediate layer is the Ti-rich phase, and the internal layer is mainly the international oxides and sulfides. With increased corrosion time and temperature, the oxide scales are gradually dissolved in the molten salt and then precipitate as a thick and non-protective scale. Chlorides cause the formation of volatile species, which makes the oxide scale disintegrate and break off. The corrosion kinetics and morphology examinations tend to support the basic dissolution model for hot corrosion mechanisms. (orig.)

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

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    J. Gawro?ski

    2010-01-01

    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.

  9. 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.

  10. 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).

  11. [Effect of biofilm on the corrosion and fouling of cast iron pipe for water supply].

    Science.gov (United States)

    Teng, Fei; Guan, Yun-Tao; Li, Sha-Sha; Zhu, Wan-Peng

    2009-02-15

    The crystalline phase and the element composition in the scales on cast iron pipe for drinking water was identified with XRD and XPS respectively to investigate the effect of biofilm existence on the corrosion and fouling of cast iron pipe. The total iron concentration in the water phase was measured simultaneously. The results showed that on 0-7 d the total iron concentration was higher in the water phase of the group with biofilm growth, but on 15-30 d it was higher in the water phase of the control without biofilm growth. The major peak of XRD patterns for the scales with biofilm growth was characterized as Fe oxide, while for the scales in the control it was always characterized as CaCO3. As presented by XPS atomic ratio, the Ca atomic percentage in the scales with biofilm growth was lower than that in the scales in the control, which might be contributed to the Ca2+ absorption by extracellular polymeric substances or Ca2+ consumption by microorganism growth. In comparison with that in the scales in the control, the iron atomic percentage in the scales with biofilm growth was higher on 7 d, while lower after 7 d. It can be concluded that on 0-7 d the existence of biofilm could promote the corrosion of cast iron pipe while inhibit corrosion after 7 d. The variance of major peak of XRD pattern and XPS atomic ratio indicated that biofilm had important effect on the configuration and composition of the scales of cast iron pipe. The corrosion inhibition of biofilm thus provided a new pathway to control the corrosion of metal pipes in drinking water distribution system. PMID:19402487

  12. Oxidation and corrosion fatigue aspects of cast exhaust manifolds

    OpenAIRE

    Ekström, Madeleine

    2015-01-01

    Emission regulations for heavy-duty diesel engines are becoming increasingly restrictive to limit the environmental impacts of exhaust gases and particles. Increasing the specific power output of diesel engines would improve fuel efficiency and greatly reduce emissions, but these changes could lead to increased exhaust gas temperature, increasing demands on the exhaust manifold material. This is currently the ferritic ductile cast iron alloy SiMo51, containing about 4 wt% Si and ~1 wt% Mo, wh...

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

    Science.gov (United States)

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

    2013-04-01

    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.

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

    Science.gov (United States)

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

    2013-06-01

    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

  15. 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)

  16. Effects of heat treatment and alloying of spheroidal graphite cast iron on corrosion resistance in aqueous environment

    Energy Technology Data Exchange (ETDEWEB)

    Aoyama, M. [Dept. of Mechanical Engineering, Daido Inst. of Tech., Aichi (Japan); Tahashi, K. [Takanich Co., Ltd. Aichi (Japan); Matsuno, K. [Fuji Die Co., Ltd. Tokyo (Japan)

    2004-07-01

    The present study examined the effects of heat treatment and the addition of Cu-Ni alloy on the corrosion resistance of the matrix of spheroidal graphite cast iron in aqueous environments. Test materials of white cast iron and carbon steel were used for comparison with spheroidal graphite cast iron. The alloy spheroidal graphite cast iron that added Cu and Ni was prepared. The spheroidal graphite cast iron was subjected to three kinds of heat treatment to adjust the matrix: annealing, oil quenching, and austemper heat treatment. In electrochemical tests, measurements of corrosion electrode potential and cathode and anode polarization were used. The following was clarified from the relationship between the electrode potential and current density of each of the materials in each of the solution. The alloy spheroidal graphite cast iron had a high corrosion electrode potential owing to the addition of Cu-Ni, and tended to have a low corrosion current density. This demonstrates that in any of the materials having a matrix adjusted by heat treatment, the addition of Cu-Ni increased the corrosion resistance. The corrosion current density was highest in a sulfuric acid environment. (orig.)

  17. Ingot cast magnesium alloys with improved corrosion resistance

    International Nuclear Information System (INIS)

    This patent describes a magnesium casting alloy. It comprises: the formula MgbalAlaZnbZc wherein X is at least one element selected from the group consisting of neodymium, praseodymium, and yttrium, a ranges from about 5 to 15 atom percent, b ranges from about 0.2 to 4 atom percent, c ranges from about 0.5 to 3 atom percent, the balance being magnesium and incidental impurities, with the proviso that the sum of aluminum and zinc present ranges from about 5 to 15 atom percent

  18. Maturation of the gastric microvasculature in Xenopus laevis (Lissamphibia, Anura) occurs at the transition from the herbivorous to the carnivorous lifestyle, predominantly by intussuceptive microvascular growth (IMG): a scanning electron microscope study of microvascular corrosion casts and correlative light microscopy

    OpenAIRE

    Lametschwandtner, Alois; Ho?ll, Monika; Bartel, Heidi; Anupunpisit, Vipavee; Minnich, Bernd

    2012-01-01

    The microvascular bed of the stomach of Xenopus laevis and the changes it undergoes when the herbivorous tadpole becomes a carnivorous adult were studied by scanning electron microscopy of vascular corrosion casts and light microscopy of stained tissue sections. In tadpoles an upper and a lower gastric artery supplied, and upper, middle and lower medial and lateral gastric veins drained the vertically extending stomach. During metamorphosis, the stomach gained a horizontal cranio-caudal exten...

  19. Residual stresses and stress corrosion effects in cast steel nuclear waste overpacks

    International Nuclear Information System (INIS)

    In the concepts for final disposal of high-level radioactive waste in Switzerland, one engineered barrier consists of an overpack made out of cast steel GS-40. Whenever tensile stresses are expected in the overpack, the issue of stress corrosion cracking must be expected. A low-strength steel was chosen to minimize potential problems associated with stress corrosion cracking. A series of measurements on stress corrosion cracking under the conditions as expected in the repository confirmed that the corrosion allowance of 50 mm used for the design of the reference overpack is sufficient over the 1000 years design lifetime. Tensile stresses are introduced by the welding process when the overpack is closed. For a multipass welding, the evolution of deformations, strains and stresses were determined in a finite-element calculation. Assuming an elastic-plastic material behavior without creep, the residual stresses are high; considering creep would reduce them. A series of creep tests revealed that the initial creep rate is important for cast steel already at 400deg C. (orig.)

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

    OpenAIRE

    Ovat, F. A.; David, F. O.; Anyandi, A. J.

    2012-01-01

    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 tha...

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

    Science.gov (United States)

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

    2014-11-15

    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

  2. The development of high strength corrosion resistant precipitation hardening cast steels

    Science.gov (United States)

    Abrahams, Rachel A.

    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

  3. 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

  4. 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.

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

    International Nuclear Information System (INIS)

    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 CeO2 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.

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

    Science.gov (United States)

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

    2012-03-15

    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

  7. 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

  8. Eddy current measurement system evaluation for corrosion depth determination on cast aluminum aircraft structure

    Science.gov (United States)

    Singh, Surendra; Greving, Dan; Kinney, Andy; Vensel, Fred; Ohm, Jim; Peeler, Mike

    2013-01-01

    An eddy current (EC) technique was developed to determine the corrosion depth on a bare flange face of a cast aluminum A356-T6 aircraft engine structure. The EC response and the corrosion depths determined through metallurgical cross sections were used to develop an empirical relation between EC response and depth. The EC technique and depth determination are used to inspect the engine structures during overhaul to determine if they are fit for continued service. An accurate and reliable Non-Destructive Inspection is required to ensure that structures returned to service are safe for continued operation. NDE system reliability demonstrations of the eddy current technique are traditionally reported in terms of Probability of Detection (POD) data using MIL-HDBK-1823A. However, the calculation of POD data is based on a simple linear predictive model that is valid only if certain criteria are met. These are: 1) NDE system response is measurable (i.e. continuous data), 2) Flaw size is known and measurable (i.e. continuous data), 3) relationship between the NDE system response and flaw size is linear (or linear on a log scale), 4) variation in measured responseresponse around a predicted response for a given flaw size is normally distributed, 5) the variation around the predicted response is constant (i.e. variation does not change with flaw size), and 6) inherent variability in the NDE system is known and fully understood. In this work, a Measurement System Evaluation (MSE) of the Eddy Current System was used to address some of these concerns. This work was completed on two aircraft structures having varying corrosion depths. The data were acquired in a random manner at fifty regions of interests (ROIs). Three operators participated in this study, and each operator measured Eddy Current response three times in each ROI. In total, there were four hundred and fifty data points collected. Following this, the two structures were sectioned for measuring corrosion depth. The obtained EC response and depth data were used for quantifying the EC System inherent variability by determining Analysis Of Variance (ANOVA), Gage R&R, control charts, Gage run charts, and regression curve. Initial results from this study show that the Eddy Current System is capable for determining corrosion depths on the structures as well as for discriminating good parts from bad.

  9. 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

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

    Directory of Open Access Journals (Sweden)

    Okada,Satoko

    1995-08-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    C.D. Lundin; S. Wen; W. Liu; G. Zhou

    2001-10-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X., E-mail: wangxiang@hrbeu.edu.cn [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Dong, L.H.; Li, J.T.; Li, X.L. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Ma, X.L. [School of Materials Science and Engineering, Harbin University of Science and Technology, Harbin 150080 (China); Zheng, Y.F. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China)

    2013-10-15

    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){sub 2}, HA and Ca{sub 3}(PO{sub 4}){sub 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.

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

    Science.gov (United States)

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

    2014-09-01

    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.

  14. A CORROSION CAST STUDY OF RAMIFICATION PATTERN OF PORTAL VEIN IN RIGHT LOBE OF HUMAN LIVER

    Directory of Open Access Journals (Sweden)

    Rajput AS

    2014-12-01

    Full Text Available Objectives: The aim of the study was to know the intrahepatic ramification pattern of portal vein in right lobe of liver & its variations. Methods: 25 human fresh livers were obtained after autopsy and studied by corrosion cast method. Polymeric granules of butyl butyrate were dissolved in acetone and 20% homogenous solution was made. Solution was injected into portal vein and the injected liver was placed in 10 % formal saline for 24 hours at room temperature (20°C for polymerization of infused butyl butyrate solution. Maceration of liver tissue achieved by whole-organ immersion in 1.8 N KOH solution at 68°C for 24 hrs. Each cast thus obtained was preserved in glycerin and details were studied. Results: The length of the right portal vein varies 0.5 to 1.8 cm (1.2 cm. The right portal vein bifurcated into second order branches - right anterior portal vein (RAPV & right posterior portal vein (RPPV in 87 % of the cases, while trifurcated in rest of 13 % of cases. The angle between the anterior and posterior division ranged from 58°-95 °. Anterio-superior (P8 branch shown three type of ramification - Bifurcation type (72 %, P8- one pedicle type (8 % and P8- trifurcation type (20%. Anterio-inferior (P5 max branch shown the three type of ramification pattern - P5 -common type (72 %, P5 – P8 anterior type (28 % but P5 – P8 posterior type was not observed. Right Posterior Portal Vein has shown three types of ramification pattern - Type I-Fan shaped (64%,Type II (28 % & Type III-Trifurcation type (8%. Conclusions: The findings of present study on hepatic vasculature have immense importance in the field of hepato-biliary surgeries like hepatic resection, segmentectomy and liver transplantation.

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

    Directory of Open Access Journals (Sweden)

    S. Holecek

    2009-04-01

    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.

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

    International Nuclear Information System (INIS)

    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 ?m/year were observed for iron in groundwater after de-aeration, but of the order of 100 ?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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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)

  18. 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

  19. Gross anatomy of the portal vein and hepatic artery ramifications in dogs: corrosion cast study.

    Science.gov (United States)

    Ursic, M; Ravnik, D; Hribernik, M; Pecar, J; Butinar, J; Fazarinc, G

    2007-04-01

    The anatomical variations of the portal vein and the hepatic artery ramifications were analysed on liver corrosion casts in 20 dogs as a possible aid in the surgical management of the organ. The portal vein ramified similarly in all dogs. It divided into the smaller right portal branch from which vessels for the caudate process and both right lobes arose and the substantial left portal branch, which supplied the remaining liver portions and in 12 cases also the dorsal part of the right lateral lobe. Right lateral, right medial and left branches are the major arteries originating from the hepatic artery; however, their origin and course varied among individual animals. In 10 livers, the right lateral and the left branches originated from the hepatic artery, while the right medial branch arose from the left branch and usually supplied the right medial lobe solely. In nine livers, the right medial branch arose directly from the hepatic artery and supplied quadrate lobe and gallbladder as well, while in one liver the common artery, which subsequently divided into lobar branches, branched away from the hepatic artery. An additional branch for the caudate process, originating directly from the hepatic artery, was observed in 10 livers. Certain liver portions received the arterial blood from two major branches, which was particularly characteristic for the right medial lobe (six livers) and caudate process (10 livers). The course of the major arterial branches was also variable, although they proceeded in close anatomical relationship with the portal vein branches. The left arterial branch accompanied the left portal branch on its dorsal aspect (15 cases) or crossed it from the caudal aspect (five cases). The right lateral branch crossed the initial parts of the left and right portal branches either from cranial (12 cases) or caudal aspects (eight cases), while the right medial branch always crossed the left portal branch from its caudal aspect. PMID:17371378

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

    OpenAIRE

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

    2009-01-01

    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...

  1. 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)

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

    2012-06-30

    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.

  2. 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)

    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

    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.

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

    Directory of Open Access Journals (Sweden)

    Wang Wei

    2014-05-01

    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.

  4. 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)

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

    Directory of Open Access Journals (Sweden)

    M.S. Priyan

    2014-12-01

    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.

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

    OpenAIRE

    Nacer ZAZI

    2013-01-01

    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...

  7. Corrosion

    Science.gov (United States)

    Slabaugh, W. H.

    1974-01-01

    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)

  8. Corrosion behaviour of water waste on the gray cast iron sanitary pipelines

    International Nuclear Information System (INIS)

    The works of Plato (427-347 B.C.) contained the written description of corrosion. Plato defined rust as the earthy component separating out of the metal. (Georgius Agrico La) held to the same opinion some 2000 years later in his great mineralogical work De Natura Fossilium Iron rust (rat. Ferrug or Rubigo) is, so to speak, assertion of metallic iron. Iron can be protected against this defect by various wrapping, such as red lead, white lead, gypsum, bitumen or tar. Gaius Secundus Pliny also mentioned bitumen, pitch, white lead, and gypsum as protecting iron and bronze against corrosion. He reported that Alexander the Great had constructed Ponton Bridge at Zeugmar on the Euphrates with the aid of an iron chain. Link's that were inserted later suffered rust attacks, While the original ones remained immune. The opinion, sometimes expressed today, that modern iron inferior and more corrosion than old iron, was thus current even in ancient times. The concept of the corrosion process derived from the latin corrodere ( to eat away, to destroy ), first appeared in the philosophical transaction in 1667. It was discussed in German from the Frensh on the manufacture of white lead in 1785 and was mentioned in 1836 in the translation of an English paper by Savy on the cathodic protection of iron in sea water. However, almost unit the present day, the term was indiscriminately for corrosion reaction effects, and corrosion damage

  9. MCC corrosion tests at reference testing conditions for A27 cast steel in Hanford ground water

    International Nuclear Information System (INIS)

    The Materials Characterization Center (MCC) at Pacific Northwest Laboratory is performing three kinds of corrosion tests for the Basalt Waste Isolation Project (BWIP) to establish the interlaboratory reproducibility and uncertainty of corrosion rates of container materials for high-level nuclear waste. The three types of corrosion tests were selected to address two distinct conditions that are expected in a repository constructed in basalt. An air/steam test is designed to address corrosion during the operational period and static pressure vessel and flowby tests are designed to address corrosion under conditions that bound the conditions during the post-closure period of the repository. The results of tests at reference testing conditions, which were defined to facilitate interlaboratory comparison of data, are presented. Data are reported for the BWIP/MCC-105.5 Air/Steam Test, BWIP/MCC-105.1 Static Pressure Vessel, and BWIP/MC-105.4 Flowby Test. In those cases where data are available from a second laboratory, a statistical analysis of interlaboratory results is reported and expected confidence intervals for mean corrosion rates are given. Other statistical treatment of data include analyses of the effects of vessel-to-vessel variations, test capsule variations for the flowby test, and oven-to-oven variations for air/steam tests. 5 references, 4 figures, 9 tables

  10. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Microstructure and Corrosion Performance of Carbonitriding Layers on Cast Iron by Plasma Electrolytic Carbonitriding

    Science.gov (United States)

    Pang, Hua; Lv, Guo-Hua; Chen, Huan; Wang, Xin-Quan; Zhang, Gu-Ling; Yang, Si-Ze

    2009-08-01

    The surface carbonitriding of cast iron is investigated in an aqueous solution of acetamide and glycerin. Microstructure, chemical and phase composition and corrosion performance of the carbonitriding layers are investigated by scanning electron microscopy, energy dispersive spectroscopy and x-ray diffraction, as well as potentiodynamic polarization testing. X-ray diffraction results show that the carbonitriding coatings are composed of martensite, austenite(?-Fe), Fe2C, Fe3C, Fe5C2, FeN and in-Fe2-3N. After the plasma electrolytic carbonitriding treatment the corrosion resistance of cast iron is clearly improved compared to the substrate, and the coatings produced at 350 V for 30s give the best corrosion resistance.

  11. Effect of bacterial communities on the formation of cast iron corrosion tubercles in reclaimed water.

    Science.gov (United States)

    Jin, Juntao; Wu, Guangxue; Guan, Yuntao

    2015-03-15

    To understand the role bacterial communities play in corrosion scale development, the morphological and physicochemical characteristics of corrosion scales in raw and disinfected reclaimed water were systematically investigated. Corrosion tubercles were found in raw reclaimed water while thin corrosion layers formed in disinfected reclaimed water. The corrosion tubercles, composed mainly of ?-FeOOH, ?-FeOOH, and CaCO3, consisted of an top surface; a shell containing more magnetite than other layers; a core in association with stalks produced by bacteria; and a corroded layer. The thin corrosion layers also had layered structures. These had a smooth top, a dense middle, and a corroded layer. They mostly consisted of the same main components as the tubercles in raw reclaimed water, but with different proportions. The profiles of the dissolved oxygen (DO) concentration, redox potential, and pH in the tubercles were different to those in the corrosion layers, which demonstrated that these parameters changed with a shift in the microbial processes in the tubercles. The bacterial communities in the tubercles were found to be dominated by Proteobacteria (56.7%), Bacteroidetes (10.0%), and Nitrospira (6.9%). The abundance of sequences affiliated to iron-reducing bacteria (IRB, mainly Geothrix) and iron-oxidizing bacteria (mainly Aquabacterium) was relatively high. The layered characteristics of the corrosion layers was due to the blocking of DO transfer by the development of the scales themselves. Bacterial communities could at least promote the layering process and formation of corrosion tubercles. Possible mechanisms might include: (1) bacterial communities mediated the pH and redox potential in the tubercles (which helped to form shell-like and core layers), (2) the metabolism of IRB and magnetic bacteria (Magnetospirillum) might contribute to the presence of Fe3O4 in the shell-like layer, while IRB contributed to green rust in the core layer, and (3) the diversity of the bacterial community resulted in the complex composition of the core layer, and gas producing bacteria (sulfate-reducing bacteria and methanogenic bacteria) played a role in the formation of the porous core layer. PMID:25618521

  12. The corrosion performance of die-cast magnesium alloy MRI230D in 3.5% NaCl solution saturated with Mg(OH)2

    International Nuclear Information System (INIS)

    The environmental behavior of die-cast magnesium alloy MRI230D designated for high-temperature applications was evaluated in comparison with regular AZ91D alloy. The microstructure examination was carried out using SEM, TEM, and X-ray diffraction analysis; the corrosion performance in 3.5% NaCl solution was evaluated by immersion test, salt spray testing, potentiodynamic polarization analysis, and stress corrosion behavior by Slow Strain Rate Testing (SSRT). Although the general corrosion resistance of MRI230D was slightly improved compared to that of AZ91D alloy its stress corrosion resistance was relatively reduced. The variations in the environmental behavior of the two alloys were mainly due to the differences in their chemical composition and microstructure after die casting. In particular, the differences were related to the reduced Al content in MRI230D and the addition of Ca to this alloy, which consequently affected its relative microstructure and electrochemical characteristics. - Research Highlights: ?Corrosion and SCC resistance of a new Mg alloy MRI230D was evaluated vs. regular AZ91D. ?MRI230D has a minor advantage in corrosion performance compared with AZ91D. ?The SCC resistance of MRI230D by SSRT analysis was relatively reduced. ?The reduced SCC resistance of MRI230D was due to the detrimental effect of Ca on ductility.

  13. The corrosion performance of die-cast magnesium alloy MRI230D in 3.5% NaCl solution saturated with Mg(OH){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Aghion, E., E-mail: egyon@bgu.ac.il; Lulu, N.

    2010-11-15

    The environmental behavior of die-cast magnesium alloy MRI230D designated for high-temperature applications was evaluated in comparison with regular AZ91D alloy. The microstructure examination was carried out using SEM, TEM, and X-ray diffraction analysis; the corrosion performance in 3.5% NaCl solution was evaluated by immersion test, salt spray testing, potentiodynamic polarization analysis, and stress corrosion behavior by Slow Strain Rate Testing (SSRT). Although the general corrosion resistance of MRI230D was slightly improved compared to that of AZ91D alloy its stress corrosion resistance was relatively reduced. The variations in the environmental behavior of the two alloys were mainly due to the differences in their chemical composition and microstructure after die casting. In particular, the differences were related to the reduced Al content in MRI230D and the addition of Ca to this alloy, which consequently affected its relative microstructure and electrochemical characteristics. - Research Highlights: {yields}Corrosion and SCC resistance of a new Mg alloy MRI230D was evaluated vs. regular AZ91D. {yields}MRI230D has a minor advantage in corrosion performance compared with AZ91D. {yields}The SCC resistance of MRI230D by SSRT analysis was relatively reduced. {yields}The reduced SCC resistance of MRI230D was due to the detrimental effect of Ca on ductility.

  14. 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)

    Jain, Syadwad

    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).

  15. Corrosion behaviour of ductile cast irons partially modified with silicon in 0.03 M NaCl; Comportamiento frente a la corrosion de fundiciones con grafito laminar y esferoidal parcialmente modificadas con silicio en NaCl 0,03 M

    Energy Technology Data Exchange (ETDEWEB)

    Arenas, M. A.; Niklas, A.; Conde, A.; Mendez, S.; Sertucha, J.; Damborenea, J. J. de

    2014-07-01

    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)

  16. The role of aluminum distribution on the local corrosion resistance of the microstructure in a sand-cast AM50 alloy

    International Nuclear Information System (INIS)

    Highlights: •Site-specific analytical electron microscopy was performed on corroded AM50. •Areas close to eutectic microstructure show less corrosion damage. •Eutectic Mg grains develop an Al-rich layer between the alloy and corrosion product. •We demonstrate, using low-loss EELS, that the Al-rich layer is metallic in character. •Primary ?-Mg grains, with lower Al content, do not develop the Al-rich layer and corrode severely. -- Abstract: Site-specific analytical electron microscopy was performed on a corroded sand-cast AM50 alloy. Areas close to partially divorced eutectic were the regions with less corrosion damage. The corrosion product layer in these areas consisted of a columnar section of predominantly amorphous MgO. At the alloy interface, an aluminum-rich layer was identified. Electron energy-loss spectroscopy suggests this layer is metallic in character. The corrosion product film on the primary ?-Mg grains possessed a bi-layer morphology: a thin columnar film and a thicker, porous sub-layer. The formation of the Al-rich layer depends on the Al content in solid solution at a specific location

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

    Directory of Open Access Journals (Sweden)

    Nacer ZAZI

    2013-09-01

    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

  18. 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

  19. Effect of heat treatment on the wear and corrosion behaviors of a gray cast iron coated with a COLMONOY 88 alloy deposited by high velocity oxygen fuel (HVOF) thermal spray

    OpenAIRE

    O?z, A.; Samur, R.; Mindivan, H.; Demir, A.; Sagiroglu, S.; Yakut, A. K.

    2013-01-01

    The present work has been conducted in order to determine the influence of heat treatment on the wear and corrosion behaviours of a gray cast iron substrate coated with a Ni base coating deposited by HVOF thermal spray. The wear resistance of the coatings was obtained using a reciprocating wear tester by rubbing a 10 mm diameter steel ball on the coatings at normal atmospheric conditions. Corrosion tests were performed using potentiodynamic polarization measurements in a 3,5 % NaCl solution. ...

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

    International Nuclear Information System (INIS)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Murillo-Gutiérrez, N.V., E-mail: murillo@chimie.ups-tlse.fr [Université de Toulouse UPS-INP-CNRS, Institut Carnot CIRIMAT, Toulouse (France); Ansart, F.; Bonino, J-P. [Université de Toulouse UPS-INP-CNRS, Institut Carnot CIRIMAT, Toulouse (France); Kunst, S.R.; Malfatti, C.F. [Universidade Federal do Rio grande do Sul, Laboratory of Corrosion Research (LAPEC), Porto Alegre (Brazil)

    2014-08-01

    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.

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

    Science.gov (United States)

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

    2014-08-01

    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.

  3. Effect of heat treatment on the wear and corrosion behaviors of a gray cast iron coated with a COLMONOY 88 alloy deposited by high velocity oxygen fuel (HVOF thermal spray

    Directory of Open Access Journals (Sweden)

    A. Öz

    2013-07-01

    Full Text Available The present work has been conducted in order to determine the influence of heat treatment on the wear and corrosion behaviours of a gray cast iron substrate coated with a Ni base coating deposited by HVOF thermal spray. The wear resistance of the coatings was obtained using a reciprocating wear tester by rubbing a 10 mm diameter steel ball on the coatings at normal atmospheric conditions. Corrosion tests were performed using potentiodynamic polarization measurements in a 3,5 % NaCl solution. It was observed that the corrosion and wear resistance of the coatings increased along with the reduction of porosity and roughness by the heat treatment.

  4. 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)

  5. 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

  6. 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 ...

  7. 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)

    Tatjana Puskar

    2014-09-01

    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.

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

    Science.gov (United States)

    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

    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.

  9. Venous drainage of the dorsal sector of the liver: differences between segments I and IX. A study on corrosion casts of the human liver.

    Science.gov (United States)

    Gadzijev, E M; Ravnik, D; Stanisavljevic, D; Trotovsek, B

    1997-01-01

    The aim of this study was to determine the venous drainage of the dorsal sector of the liver in order to define the differences between segments I and IX and their implications for sectorially and segmentally oriented hepatic surgery. The study was based on corrosion casts of 61 macroscopically healthy livers. The drainage pathways of veins at least 10 mm long and 1 mm wide were evaluated and statistically analysed. On average, 9 veins drained the two segments and three veins from both segments entered the inferior vena cava. In 95% of cases the veins from segment I drained predominantly into the inferior vena cava, whereas in segment IX this pathway was dominant in only 30% of cases. In 64% of cases a vein originating in segment IX entered the right hepatic v. The difference in the venous drainage of the two segments suggests that segment IX partly belongs to the neighbouring segments and may thus be only a paracaval region of the right liver. PMID:9210240

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

    Science.gov (United States)

    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

    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.

  11. 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

  12. 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.

  13. 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)

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

    2014-06-01

    Full Text Available 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.

  14. Bimetallic layered castings alloy steel – grey cast iron

    Directory of Open Access Journals (Sweden)

    T. Wróbel

    2011-04-01

    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

  15. 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)

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

    2008-06-01

    Full Text Available 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.

  16. Centrifugally cast for top performance

    International Nuclear Information System (INIS)

    Centrifugally cast nickel-chromium alloy components, supplied by Fahralloy-Wisconsin Ltd. are being used for the lattice tubes in CANDU reactors. Horizontal centrifugal casting facilities enable tubular shapes to be made with outside diameters of 3 to 23 in.; lengths of up to 162 in. A unique feature of horizontal casting is that the mechanical properties are the same in all directions. The structure is also completely homogeneous and combines characteristically high resistance to heat and corrosion with enhanced physical and mechanical properties. (R.A.)

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

    Science.gov (United States)

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

    1981-01-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Peng Hao

    2011-02-01

    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.

  19. 77 FR 17119 - Pipeline Safety: Cast Iron Pipe (Supplementary Advisory Bulletin)

    Science.gov (United States)

    2012-03-23

    ...from service cast iron pipe that may threaten the...leakage, history, corrosion, and other unusual operating...Subject: Cast Iron Pipe (Supplementary Advisory...serviceability of cast iron pipe and schedule its replacement...leakage, history, corrosion, and other unusual...

  20. 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)

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

    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.

  1. Influence of reinforcement proportion and matrix composition on pitting corrosion behaviour of cast aluminium matrix composites (A3xx.x/SiCp)

    International Nuclear Information System (INIS)

    The influence of silicon carbide (SiCp) proportion and matrix composition on four aluminium metal matrix composites (A360/SiC/10p, A360/SiC/20p, A380/SiC/10p, A380/SiC/20p) immersed in 1-3.5 wt% NaCl at 22 deg C was investigated by potentiodynamic polarization. The kinetics of the corrosion process was studied on the basis of gravimetric measurements. The nature of corrosion products was analysed by scanning electron microscopy (SEM) and low angle X-ray diffraction (XRD). The corrosion damage in Al/SiCp composites was caused by pitting attack and by nucleation and growth of Al2O3 . 3H2O on the material surface. 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 and saline concentration

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

    Science.gov (United States)

    Deadmore, D. L.

    1984-01-01

    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.

  3. The cathodic behaviour of Al–Mn precipitates during atmospheric and saline aqueous corrosion of a sand-cast AM50 alloy

    International Nuclear Information System (INIS)

    Highlights: • Site-specific analytical electron microscopy was performed on corroded AM50. • In air-exposed alloy, Al–Mn particles show enrichment in Al and O at the surface. • In immersed AM50, Al–Mn particles develop domes of corrosion products, Mg(OH)2/MgO. • Immersed intermetallics show Al depletion at the surface, indicating high local pH. • Al depletion leads to surface delamination and ultimately formation of Mn3O4. - Abstract: The behaviour of Al–Mn precipitates during atmospheric and aqueous corrosion of an AM50 Mg alloy was investigated using site-specific analytical electron microscopy. After air-exposure, localized attack was observed close to Al–Mn precipitates, with the top layer of the intermetallic enriched in Al and O. During immersed corrosion, these precipitates developed protruding domes of corrosion products, with crystalline Mg(OH)2 on top and an inner layer of crystalline MgO. After prolonged immersion, these precipitates showed evidence of preferential Al dissolution, ultimately developing a fragmented interlayer of Mn3O4. This phase transformation is linked to the enhanced hydrogen evolution rates adjacent to these precipitates

  4. VASCULAR DEMENTIA

    Directory of Open Access Journals (Sweden)

    Maria Alekseyevna Cherdak

    2010-03-01

    vascular cognitive disorders and vascular dementia (VD. The heterogeneity of vascular cognitive disorders, concurrence of vascular and neurodegenerative diseases are discussed. Data from studies of specific therapy for VD are given.

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

    Science.gov (United States)

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

    1987-01-01

    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.

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

    Science.gov (United States)

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

    2015-04-01

    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.

  7. Enrichment of Casting Surface in Founding Process

    OpenAIRE

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

    2007-01-01

    A lot of cast steel and cast iron properties, also usable, depend on physical and chemical properties of surface layer, such as: hardness, corrosion resistance, abrasive wear resistance. The paper presents directly method of surface enrichment on casting in founding process. Layer in form of high-speed steel HS 18–0–1plate was placed on G25CrSiMnMoNi 4–4–4–2,5–4 cast steel hammer of crusher. To investigations it was used light microscopy and scanning electron microscope. Microanal...

  8. 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

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

    Directory of Open Access Journals (Sweden)

    A Hodži?

    2013-03-01

    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.

  10. Dictionary corrosion and corrosion control

    International Nuclear Information System (INIS)

    This dictionary has 13000 entries in both languages. Keywords and extensive accompanying information simplify the choice of word for the user. The following topics are covered: Theoretical principles of corrosion; Corrosion of the metals and alloys most frequently used in engineering. Types of corrosion - (chemical-, electro-chemical, biological corrosion); forms of corrosion (superficial, pitting, selective, intercrystalline and stress corrosion; vibrational corrosion cracking); erosion and cavitation. Methods of corrosion control (material selection, temporary corrosion protection media, paint and plastics coatings, electro-chemical coatings, corrosion prevention by treatment of the corrosive media); Corrosion testing methods. (orig./HP)

  11. Developing of chromium cast steel on sleeves of heavy machines

    OpenAIRE

    J. Kilarski; A. Studnicki; J. Sucho?

    2010-01-01

    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.

  12. Urinary casts

    Science.gov (United States)

    ... examined under the microscope during a test called urinalysis . Urinary casts may be made up of white ... of the urologic patient: history, physical examination, and urinalysis. In: Wein AJ, Kavoussi LR, Novick AC, et ...

  13. Pigmented casts.

    Science.gov (United States)

    Miteva, Mariya; Romanelli, Paolo; Tosti, Antonella

    2014-01-01

    Pigmented casts have been reported with variable frequency in scalp biopsies from alopecia areata, trichotillomania, chemotherapy-induced alopecia and postoperative (pressure induced) alopecia. Their presence and morphology in other scalp disorders has not been described. The authors assessed for the presence and morphology of pigmented casts in 308 transversely bisected scalp biopsies from nonscarring and scarring alopecia, referred to the Department of Dermatology, University of Miami within a year. The pigmented casts were present in 21 of 29 cases of alopecia areata (72%), 7 of 7 cases of trichotillomania (100%), 1 case of friction alopecia, 4 of 28 cases of central centrifugal cicatricial alopecia (14%), and 4 of 4 cases of dissecting cellulitis (100%). They did not show any distinguishing features except for the morphology in trichotillomania, which included twisted, linear (zip), and "button"-like pigment aggregation. The linear arrangement was found also in friction alopecia and dissecting cellulitis. Pigmented casts in the hair canals of miniaturized/vellus hairs was a clue to alopecia areata. Pigmented casts can be observed in biopsies of different hair disorders, but they are not specific for the diagnosis. Horizontal sections allow to better assess their morphology and the follicular level of presence of pigmented casts, which in the context of the other follicular findings may be a clue to the diagnosis. PMID:23823025

  14. On Tool Failure in Die Casting

    OpenAIRE

    Persson, Anders

    2003-01-01

    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...

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

    Science.gov (United States)

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

    2014-10-01

    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.

  16. 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

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

    Directory of Open Access Journals (Sweden)

    Z. Stradomski

    2010-07-01

    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.

  18. Nodular cast iron and casting monitoring

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2008-10-01

    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.

  19. Nodular cast iron and casting monitoring

    OpenAIRE

    Pietrowski, S.; Rapiejko, C.

    2008-01-01

    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.

  20. Vascular Access

    Directory of Open Access Journals (Sweden)

    Berna YELKEN

    2011-09-01

    Full Text Available Hemodialysis patients are connected to life by means of vascular access. The complications of vascular access represent one of the most important causes of morbidity, mortality and high healthcare costs in the hemodialysis patients. Although it is known that the best vascular access is AVF, the fistula use rate is still low in most countries. This review will examine; association of various vascular access with morbidity, mortality and dialysis costs; different practice patterns in the world and reasons of this; finally, solutions for vascular access problems.

  1. Fabrication of bulk metallic glasses by centrifugal casting method

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2007-01-01

    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.

  2. Casting materials

    Science.gov (United States)

    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

    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.

  3. Enrichment of Casting Surface in Founding Process

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2007-07-01

    Full Text Available A lot of cast steel and cast iron properties, also usable, depend on physical and chemical properties of surface layer, such as: hardness, corrosion resistance, abrasive wear resistance. The paper presents directly method of surface enrichment on casting in founding process. Layer in form of high-speed steel HS 18–0–1plate was placed on G25CrSiMnMoNi 4–4–4–2,5–4 cast steel hammer of crusher. To investigations it was used light microscopy and scanning electron microscope. Microanalysis of chemical microanalysis of chemical composition and hardness measurements of transient zone between cast steel and steel were made. Analysis of research result show that, exists possibility of increase in hardness and abrasive wear resistance by put on casting surface a tool steel or sintered carbides plates, which are from scrap after waste of turning tool or face milling cutter. Moreover, applied activated alloy is very useful in this method of casting surface enrichment directly in founding process.

  4. Remodeling of hepatic vascular changes after specific chemotherapy of schistosomal periportal fibrosis

    Scientific Electronic Library Online (English)

    Zilton A, Andrade; Ana Paula, Baptista; Thaynã Souto, Santana.

    2006-10-01

    Full Text Available Hepatosplenic schistosomiasis was the first human disease in which the possibility of extensive long standing hepatic fibrosis being degraded and removed has been demonstrated. When such changes occurred, the main signs of portal hypertension (splenomegaly, esophageal varices) progressively disappea [...] red, implying that a profound vascular remodeling was concomitantly occurring. Hepatic vascular alterations associated with advanced schistosomiasis have already been investigated. Obstruction of the intrahepatic portal vein branches, plus marked angiogenesis and compensatory hyperplasia and hypertrophy of the arterial tree are the main changes present. However, there are no data revealing how these vascular changes behave during the process of fibrosis regression. Here the mouse model of pipestem fibrosis was used in an investigation about these vascular alterations during the course of the infection, and also after treatment and cure of the disease. Animals representing the two polar hepatic forms of the infection were included: (1) "isolated granulomas" characterized by isolated periovular granulomas sparsely distributed throughout the hepatica parenchyma; and (2) 'pipestem fibrosis' with periovular granulomas and fibrosis being concentrated within portal spaces, before and after treatment, were studied by means of histological and vascular injection-corrosion techniques. Instances of widespread portal vein obstruction of several types were commonly found in the livers of the untreated animals. These obstructive lesions were soon repaired, and completely disappeared four months following specific treatment of schistosomiasis. Treatment was accomplished by the simultaneous administration of praziquantel and oxamniquine. The most impressive results were revealed by the technique of injection of colored masses into the portal system, followed by corrosion in strong acid. The vascular lesions of non-treated pipestem fibrosis were represented in the plastic casts by considerable diminution of the fine peripheral portal vein radicles, plus dilatation of periportal collaterals. Four months after treatment, this last picture appeared replaced by tufts of newly interwoven vessels formed along the main portal vein branches, disclosing a strong angiomatoid reparative change. Understanding about the cellular elements at play during fibro-vascular repairing changes of hepatic schistosomiais represents a matter of considerable scientific and conceptual importance. At present time one may only speculate about the participation of some type of natural stem-cell capable of restoring the diseased liver back to normal once the cause of the disorder has been eliminated.

  5. Corrosion engineering

    Energy Technology Data Exchange (ETDEWEB)

    Fontana, M.G.

    1986-01-01

    This book emphasizes the engineering approach to handling corrosion. It presents corrosion data by corrosives or environments rather than by materials. It discusses the corrosion engineering of noble metals, ''exotic'' metals, non-metallics, coatings, mechanical properties, and corrosion testing, as well as modern concepts. New sections have been added on fracture mechanics, laser alloying, nuclear waste isolation, solar energy, geothermal energy, and the Statue of Liberty. Special isocorrosion charts, developed by the author, are introduced as a quick way to look at candidates for a particular corrosive.

  6. The ancient Chinese casting techniques

    OpenAIRE

    Tan Derui; Lian Haiping

    2011-01-01

    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...

  7. Corrosion in seawater systems

    International Nuclear Information System (INIS)

    Highly alloyed stainless steels have been exposed to natural chlorinated and chlorine-free seawater at 35 deg. C. Simulated tube-tubesheet joints, weld joints and galvanic couples with titanium, 90/10 CuNi and NiAl bronze were tested and evaluated for corrosion. The corrosion rates of various anode materials - zinc, aluminium and soft iron - were also determined. Finally the risk of hydrogen embrittlement of tubes of ferritic stainless steels and titanium as a consequence of cathodic protection was studied. An attempt was also made to explain the cracking mechanism of the ferritic steels by means of transmission electron microscopy. One important conclusion of the project is that chlorinated seawater is considerably more corrosive to stainless steels than chlorine-free water, whereas chlorination reduces the rate of galvanic corrosion of copper materials coupled to stainless steels. Hydrogen embrittlement of ferritic stainless steels and titanium as a consequence of cathodic protection of carbon steel or cast iron in the same structure can be avoided by strict potentiostatic control of the applied potential. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-09-30

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-09-30

    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.

  10. Vascular Depression

    Directory of Open Access Journals (Sweden)

    Yunus Emre Sönmez

    2013-03-01

    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

  11. Thin Wall Iron Castings

    Energy Technology Data Exchange (ETDEWEB)

    J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka

    2001-10-31

    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.

  12. Phase Transformation in Cast Superaustenitic Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Nathaniel Steven Lee Phillips

    2006-12-12

    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.

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

    OpenAIRE

    Xiao Xiaofeng; Ye Shengping; Yin Weixin

    2012-01-01

    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...

  14. 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)

  15. Fatigue Assessment of Cast Components : Influence of Cast Defects

    OpenAIRE

    Bjo?rkblad, Anders

    2008-01-01

     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 ...

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

    OpenAIRE

    Yanling Ni

    2014-01-01

    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 t...

  17. Casting materials and their application in research and teaching.

    Science.gov (United States)

    Haenssgen, Kati; Makanya, Andrew N; Djonov, Valentin

    2014-04-01

    From a biological point of view, casting refers to filling of anatomical and/or pathological spaces with extraneous material that reproduces a three-dimensional replica of the space. Casting may be accompanied by additional procedures such as corrosion, in which the soft tissue is digested out, leaving a clean cast, or the material may be mixed with radiopaque substances to allow x-ray photography or micro computed topography (µCT) scanning. Alternatively, clearing of the surrounding soft tissue increases transparency and allows visualization of the casted cavities. Combination of casting with tissue fixation allows anatomical dissection and didactic surgical procedures on the tissue. Casting materials fall into three categories namely, aqueous substances (India ink, Prussian blue ink), pliable materials (gelatins, latex, and silicone rubber), or hard materials (methyl methacrylates, polyurethanes, polyesters, and epoxy resins). Casting has proved invaluable in both teaching and research and many phenomenal biological processes have been discovered through casting. The choice of a particular material depends inter alia on the targeted use and the intended subsequent investigative procedures, such as dissection, microscopy, or µCT. The casting material needs to be pliable where anatomical and surgical manipulations are intended, and capillary-passable for ultrastructural investigations. PMID:24564951

  18. Bimetallic layer castings

    OpenAIRE

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

    2010-01-01

    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...

  19. LLNL casting technology

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-01-01

    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 compentiveness 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.

  20. Special thermite cast irons

    Directory of Open Access Journals (Sweden)

    Yu. Zhiguts

    2008-07-01

    Full Text Available The given paper deals with the problems of the synthesis of cast iron by metallothermy synthesis. On the basis of investigated method of calculations structures of charges have been arranged and cast iron has been synthesized further. Peculiarities metallothermic smelting were found, mechanical properties and structure of received cast iron were investigated and different technologies for cast iron receiving were worked out.

  1. High quality casting materials

    OpenAIRE

    Pietrowski, S.

    2010-01-01

    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...

  2. Egyptian Caste System

    Science.gov (United States)

    Ms. Issen

    2009-09-17

    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 ...

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

    OpenAIRE

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

    2011-01-01

    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...

  4. Corrosion Engineering.

    Science.gov (United States)

    White, Charles V.

    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…

  5. Corrosion inhibitors

    International Nuclear Information System (INIS)

    In this paper, we briefly describe the characteristics, cost and electrochemical nature of the corrosion phenomena as well as some of the technologies that are currently employed to minimize its effect. The main subject of the paper however, deals with the description, classification and mechanism of protection of the so-called corrosion inhibitors. Examples of the use of these substances in different aggressive environments are also presented as means to show that these compounds, or their combination, can in fact be used as excellent and relatively cheap technologies to control the corrosion of some metals. In the last part of the paper, the most commonly used techniques to evaluate the efficiency and performance of corrosion inhibitors are presented as well as some criteria to make a careful and proper selection of a corrosion inhibitor technology in a given situation. (Author) 151 refs

  6. High quality casting materials

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2010-11-01

    Full Text Available 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 significant mechanical properties and high wear resistance. It was also discussed getting of layer products by combination of steel or cast iron using alphinated layer with silumin.Practical implications: The paper discusses the high quality cast alloy, layer products and presents the high quality casting materials in the point of view principles of materials selection.Originality/value: The above problem is shown in the background of “Rules of material selection” as well as a model of production system in company.

  7. External corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Place, T. [Corrosion Service Company Ltd., Edmonton, AB (Canada); Worthingham, B. [TransCanada PipeLines Ltd., Calgary, AB (Canada); Jack, T. [Nova Chemicals Ltd., Calgary, AB (Canada); Gummow, B.; Woloschuk, B. [Corrosion Service Co. Ltd., Downsview, ON (Canada)

    2003-07-01

    The 5 presentations featured by Working Group 10 focused on environmental issues, codes and standards modelling for external pipeline corrosion. Recent studies on the environmental impact of impressed current ground beds were reviewed along with ramifications to the corrosion control industry. The need to better understand the effects from anode bed operations was emphasized, particularly since there are individual landowners who would be concerned if the soil is altered. The main objective of this session was to explore differences in code interpretation and to determine if codes and standards adequately address the intention of asset management. Recent field validation of corrosion growth models were reviewed and the limitations of corrosion growth models were determined. In addition, recent developments in external corrosion mapping methods were presented. One of the topics of discussion was pipeline corrosion caused by alternating current and telluric currents. Another dealt with quality assurance and data auditing of cathodic protection surveys. A question and answer period followed each of the discussions. It was recommended that future discussions focus on the effects of all factors related to external corrosion. tabs., figs.

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

    DEFF Research Database (Denmark)

    Ambat, Rajan; Aung, Naing Naing

    2000-01-01

    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.

  9. PLANT DIVERSITY OF THE ZHELTOKAMENSKIY OPEN CAST MINES

    Directory of Open Access Journals (Sweden)

    Yarova T.A.

    2012-11-01

    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.

  10. Quality control of cast brake discs

    Directory of Open Access Journals (Sweden)

    M. Stawarz

    2008-04-01

    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.

  11. Polarization Behavior of Squeeze Cast Al2O3 Fiber Reinforced Aluminum Matrix Composites

    International Nuclear Information System (INIS)

    Electrochemical polarization behavior of squeeze cast Al2O3 short fiber reinforced Al alloy matrix composites was investigated for the basic understanding of the corrosion properties of the composites. The composites were fabricated with variations of fiber volume fraction and matrix alloys. It was found that the reinforced composites are more susceptible to corrosion attack than the unreinforced matrix alloys in general. Corrosion resistance shows decreasing tendency with increasing Al2O3 fiber volume fraction in AC8A matrix. Effect of the matrix alloys revealed that the AC8A Al matrix composite is less susceptible to corrosion attack than the 2024 and 7075 Al matrix composites. Effect of plastic deformation on electrochemical polarization behavior of the squeeze cast Al/Al2O3 composites was examined after extrusion of AC8A-10v/o Al2O3. Result shows that corrosion resistance is deteriorated after plastic deformation

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

    OpenAIRE

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

    2011-01-01

    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...

  13. 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)

  14. Degradation of stainless castings. A literature study

    International Nuclear Information System (INIS)

    Duplex cast stainless steels, containing mainly austenite and some ferrite, is used for different components in light water reactors. These alloys have good mechanical properties, good weldability, and they are resistant to intergranular stress corrosion cracking (IGSCC). Examples of components where cast duplex stainless steel is used are pump housings, valves and pipe elbows. A model for the aging/embrittlement of these materials when used in light water reactors has been developed. The model is based on regression of a large data matrix. It is mainly the impact energy (Charpy V) that has been regarded. The model only requires knowledge of the chemical composition of the material but the prediction can be improved if additional data like initial impact properties and measured ferrite content are available. The model is also capable of predicting fracture toughness. The susceptibility to IGSCC in BWR environment is primarily determined by the amount of ferrite and the carbon content of the material. When the amount of ferrite exceeds 12%, IGSCC has not been observed regardless of the carbon content. At carbon contents lower than 0.035% in weld-sensitized material IGSCC was not observed regardless of the ferrite content. Data for corrosion fatigue in primary PWR and BWR environment are available. Under BWR conditions the crack propagation rate is decreased with decreasing corrosion potential, consequently also with decreasing oxygen content of the water. Some areas have been identified where additional work is needed. In all cases the efforts should focus on characterizing cast duplex stainless steel components removed from Swedish reactors. The characterization should include: Microstructure and chemical analysis, susceptibility to IGSCC, and a comparison with existing models for embrittlement. 24 refs, 12 figs

  15. Evolution of halictine castes

    Science.gov (United States)

    Knerer, Gerd

    1980-03-01

    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.

  16. Multi-layers castings

    OpenAIRE

    J. Szajnar; P. Wróbel; T. Wróbel

    2010-01-01

    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...

  17. Vascular reactivity.

    Science.gov (United States)

    Baron, A D

    1999-07-01

    Endothelial dysfunction appears to be an integral aspect of the insulin resistance syndrome, independently of hyperglycemia. The ability of insulin to cause endothelium-derived nitric oxide (NO)-dependent vasodilation amplifies its overall effect of stimulating skeletal muscle glucose uptake and modulating vascular tone. The dose-dependent physiologic increase in skeletal muscle blood flow in response to insulin, which is highly associated with the rate of glucose metabolism, is impaired in insulin-resistant states. Insulin appears to mediate vasodilation by direct stimulation of release of NO from endothelium. Studies of the response to the endothelium-dependent vasodilator methacholine chloride in lean and obese nondiabetic subjects and obese subjects with type 2 diabetes mellitus indicate that there may be marked endothelial dysfunction very early in insulin resistance. The potent vasoprotective effects of NO mitigate various atherogenic processes, including vascular smooth muscle cell proliferation, platelet adhesion and thrombogenesis, lipid peroxidation, and monocyte adhesion to endothelial cells. The interaction between insulin and NO may contribute to the prominent outcomes of insulin resistance syndrome (viz., hypertension, thrombosis, and atherosclerosis). PMID:10418855

  18. Age-dependent changes in the pigeon bursa of Fabricius vasculature: a comparative study using light microscopy and scanning electron microscopy of vessel casts

    Science.gov (United States)

    Abbate, Franco; Pfarrer, Christiane; Jones, Carolyn J P; Ciriaco, Emilia; Germanà, Giovanni; Leiser, Rudolf

    2007-01-01

    The present study was carried out to analyse the vascularization of the pigeon bursa cloacalis of Fabricius and to determine whether it undergoes age-dependent changes during its functionally most important growth period after hatching of the pigeon. Morphological assessment of vascular corrosion casts, studied qualitatively and quantitatively, was applied for the first time to investigate the vascularization of the pigeon pigeon bursa of Fabricius. This also allowed us to analyse the microvasculature and morphological aspects of the vessel interrelationships as occurring in the natural state. The casts were compared with histological sections stained by haematoxylin-eosin and by binding of the lectin e-PHA (Phaseolus vulgaris, erythroagglutinin) to blood vessels. The vascular architecture of the bursa of Fabricius of the pigeon revealed that the organ is irrigated via two pathways, first through the terminal capillary system of lymphoid follicles arising from the internal pudendal artery, and secondly through arteries originating from the cloacal vasculature of the collum of the organ supplying the periluminal capillary system of the pigeon bursa of Fabricius. Both systems are drained by a venous system which is collateral to the system of the internal pudendal artery and clearly functions as a direct link between the lumen and vasculature of the cloaca or gut, respectively, and the bursa fabricii. This could allow the lymphocytes to be confronted with antigens from the contents of the gut, and their subsequent transport into the secondary lymphoid organs of the organism. Our results demonstrate that the blood vessels, as major and supplying part of the lymphoid system of the bursa Fabricii, clearly reflect three different phases of development: the evolution phase from about day 20 until day 50 post-hatching, the mature phase from days 50 to 90, and the involution phase after day 90. During the evolution phase the density of the vessel system rapidly increases, while in the mature phase the vascular architecture is maintained. The involution phase is dominated by vascular degeneration combined with shrinkage of the whole organ. Therefore, the morphology of the vasculature distinctly reflects the functional status of this primary lymphoid organ during its lifespan. PMID:17573827

  19. Electrochemical behaviour and corrosion of Mg-Y alloys

    International Nuclear Information System (INIS)

    Highlights: ? The corrosion performance of Mg-Y alloys reported over the largest compositional range to date. ? Quantitative microscopy identified the Mg-Y intermetallic that formed. ? Quantification of intermetallic electrochemistry via the microcell technique. ? A rational description of the corrosion response for Mg-Y alloys based on kinetics is given. - Abstract: Corrosion of cast magnesium-yttrium (Y) alloys with systematic Y additions up to a nominal 18 wt.% were studied. Corrosion performance was related to the quantitative alloy microstructure and found to increase significantly with the level of alloying and volume fraction of the Mg-Y intermetallic present. In the alloy microstructures, Mg24Y5 was principally formed; the electrochemistry of which was characterised using the electrochemical microcell method. Electrochemical testing revealed the fundamental corrosion behaviour of Mg-Y alloys and elucidated the corrosion mechanisms at play.

  20. Electrochemical behaviour and corrosion of Mg-Y alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sudholz, A.D.; Gusieva, K. [ARC Centre of Excellence for Design in Light Metals, Department of Materials Engineering, Monash University, 3800 Victoria (Australia); Chen, X.B. [CAST-CRC, Department of Materials Engineering, Monash University, 3800 Victoria (Australia); Muddle, B.C. [ARC Centre of Excellence for Design in Light Metals, Department of Materials Engineering, Monash University, 3800 Victoria (Australia); Gibson, M.A. [CSIRO Process Science and Engineering, Private Bag 33, Clayton South MDC, Clayton 3169, Victoria (Australia); Birbilis, N., E-mail: nick.birbilis@monash.ed [ARC Centre of Excellence for Design in Light Metals, Department of Materials Engineering, Monash University, 3800 Victoria (Australia); CAST-CRC, Department of Materials Engineering, Monash University, 3800 Victoria (Australia)

    2011-06-15

    Highlights: {yields} The corrosion performance of Mg-Y alloys reported over the largest compositional range to date. {yields} Quantitative microscopy identified the Mg-Y intermetallic that formed. {yields} Quantification of intermetallic electrochemistry via the microcell technique. {yields} A rational description of the corrosion response for Mg-Y alloys based on kinetics is given. - Abstract: Corrosion of cast magnesium-yttrium (Y) alloys with systematic Y additions up to a nominal 18 wt.% were studied. Corrosion performance was related to the quantitative alloy microstructure and found to increase significantly with the level of alloying and volume fraction of the Mg-Y intermetallic present. In the alloy microstructures, Mg{sub 24}Y{sub 5} was principally formed; the electrochemistry of which was characterised using the electrochemical microcell method. Electrochemical testing revealed the fundamental corrosion behaviour of Mg-Y alloys and elucidated the corrosion mechanisms at play.

  1. Alpha case formation mechanism in Ti-6Al-4V alloy investment castings using YFSZ shell moulds

    OpenAIRE

    Bauristhene, A.M.; Mutombo, Kalenda; Stumpf, Waldo E.

    2013-01-01

    Ti-64, which accounts for more than 50% of the worldwide titanium tonnage, has found commercial importance in industries requiring components with high specific strength and resistance to corrosion. Investment casting is the preferred production method due to the difficult machinability of the alloy. This study was aimed at investigating the mechanism and the extent of alpha case formation on Ti- 64 components cast using the investment casting method with YFSZ (yttria fu...

  2. Corrosion resistance of Mg-RE-Zr alloys

    OpenAIRE

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

    2007-01-01

    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...

  3. Further studies of the anaerobic corrosion of steel in bentonite

    International Nuclear Information System (INIS)

    In the horizontal emplacement concept (KBS-3H) for the disposal of radioactive waste, which is being developed in Sweden and Finland, copper canisters with cast iron inserts will be surrounded by bentonite buffer and mounted in perforated carbon steel support structures in boreholes within the bedrock. The groundwater will be reducing, leading to anaerobic corrosion of the ferrous material. It is important to understand both the effect of bentonite on the corrosion behaviour of the steel and the effect of the corrosion products on the performance of the bentonite. Previous work on the corrosion of steel in bentonite was extended to investigate a wider range of conditions, including the possible effects of alkaline plumes released from concrete support structures and the effect of chloride concentration and temperature on the corrosion rate of steel in bentonite. Corrosion rates were measured by collecting hydrogen produced by the anaerobic corrosion of iron. In addition, a range of analytical techniques was applied to study the composition and morphology of the corrosion products and the distribution and chemical state of the iron released into the bentonite. Comparison was also made between corrosion in compacted bentonite and artificial bentonite porewater. In the presence of bentonite, the corrosion product layer was relatively thin compared to fully aqueous conditions, probably because the ferrous ions released by corrosion exchanged with the bentonite interlayer n exchanged with the bentonite interlayer or attached to the surface of the bentonite grains, rather than forming a separate iron oxide phase. (author)

  4. The spheroidisation of VC carbides in high- vanadium cast iron

    Directory of Open Access Journals (Sweden)

    M. Kawalec

    2011-07-01

    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

  5. Cast iron - a predictable material

    OpenAIRE

    Sturm, Jorg C.; Guido Busch

    2011-01-01

    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...

  6. 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.)

  7. 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.)

  8. Bimetallic layer castings

    Directory of Open Access Journals (Sweden)

    M. Cholewa

    2010-11-01

    Full Text Available 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 testing and examination of the structure and selected usable properties i.e. hardness.Findings: The results of studies and their analysis show efficiency of new, innovative technology of heat-resisting layer castings.Research limitations/implications: In further research, authors of this paper are going to application of different type of alloy steels on working part (layer of bimetallic casting.Practical implications: On the basis of research results was affirmed that application of thinner plates i.e. about thickness 2mm causes their deformation in time of pouring, what disqualify this layer casting for industrial application. Considerably best results was obtained with use thickness of plate 5mm.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.

  9. Higher Education's Caste System

    Science.gov (United States)

    Iannone, Ron

    2004-01-01

    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…

  10. Closed aluminium skeleton casting

    Directory of Open Access Journals (Sweden)

    M. Dziuba-Ka?u?a

    2008-03-01

    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.

  11. 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

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

    OpenAIRE

    Ramesh Chowdhary; Rao, Srinivasa B.

    2011-01-01

    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...

  13. Solidification and casting

    CERN Document Server

    Cantor, Brian

    2002-01-01

    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.

  14. Multi-layers castings

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2010-01-01

    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.

  15. Metal Corrosion

    Science.gov (United States)

    Stoebe, Thomas G.

    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.

  16. Corrosion protection of low-carbon steel using exopolysaccharide coatings from Leuconostoc mesenteroides.

    Science.gov (United States)

    Finkenstadt, Victoria L; Côté, Gregory L; Willett, J L

    2011-06-01

    Corrosion of metals is a serious and challenging problem faced worldwide by industry. Purified Leuconostoc mesenteroides exopolysaccharide (EPS) coatings, cast from aqueous solution, inhibited the corrosion of low-carbon steel as determined by electrochemical impedance spectroscopy (EIS). There were two different corrosion behaviors exhibited when EPS films from different strains were cast onto the steel. One EPS coating reacted immediately with the steel substrate to form an iron (III) oxide layer ("rust") during the drying process while another did not. The samples that did not flash corrode had higher corrosion inhibition and formed an iron (II) passivation layer during EIS testing that persisted after the cells were disassembled. Corrosion inhibition was strain-specific as polysaccharides with similar structure did not have the same corrosion potential. PMID:21290167

  17. The ancient Chinese casting techniques

    Directory of Open Access Journals (Sweden)

    Tan Derui

    2011-02-01

    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.

  18. Corrosion inhibitors

    International Nuclear Information System (INIS)

    The corrosion inhibition efficiencies of some triazole, oxadiazole and thiadiazole derivatives for steel in presence of acidic medium have been studied by using AM1, PM3, MINDO/3 and MNDO semi-empirical SCF molecular orbital methods. Geometric structures, total negative charge on the molecule (TNC), highest occupied molecular energy level (E HOMO), lowest unoccupied molecular energy level (E LUMO), core-core repulsion (CCR), dipole moment (?) and linear solvation energy terms, molecular volume (V i) and dipolar-polarization (? *), were correlated to corrosion inhibition efficiency. Four equations were proposed to calculate corrosion inhibition efficiency. The agreement with the experimental data was found to be satisfactory; the standard deviations between the calculated and experimental results ranged between ±0.03 and ±4.18. The inhibition efficiency was closely related to orbital energies (E HOMO and E LUMO) and ?. The correlation between quantum parameters and experimental inhibition efficiency has been validated by single point calculations for the semi-empirical AM1 structures using B3LYP/6-31G** as a higher level of theory. The proposed equations were applied to predict the corrosion inhibition efficiency of some related structures to select molecules of possible activity from a presumable library of compounds

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

    Science.gov (United States)

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

    2014-12-01

    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

  20. Cast iron zinc galvanizing improved by high temperature oxidation process

    Directory of Open Access Journals (Sweden)

    D. J?drzejczyk

    2010-11-01

    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.

  1. Clean Metal Casting

    Energy Technology Data Exchange (ETDEWEB)

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The objective of this project is to develop a technology for clean metal processing that is capable of consistently providing a metal cleanliness level that is fit for a given application. The program has five tasks: Development of melt cleanliness assessment technology, development of melt contamination avoidance technology, development of high temperature phase separation technology, establishment of a correlation between the level of melt cleanliness and as cast mechanical properties, and transfer of technology to the industrial sector. Within the context of the first task, WPI has developed a standardized Reduced Pressure Test that has been endorsed by AFS as a recommended practice. In addition, within the context of task1, WPI has developed a melt cleanliness sensor based on the principles of electromagnetic separation. An industrial partner is commercializing the sensor. Within the context of the second task, WPI has developed environmentally friendly fluxes that do not contain fluorine. Within the context of the third task, WPI modeled the process of rotary degassing and verified the model predictions with experimental data. This model may be used to optimize the performance of industrial rotary degassers. Within the context of the fourth task, WPI has correlated the level of melt cleanliness at various foundries, including a sand casting foundry, a permanent mold casting foundry, and a die casting foundry, to the casting process and the resultant mechanical properties. This is useful in tailoring the melt cleansing operations at foundries to the particular casting process and the desired properties of cast components.

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

    OpenAIRE

    Chaturvedi T

    2009-01-01

    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...

  3. The Development of Corrosion Resistant Zirconium Alloy

    International Nuclear Information System (INIS)

    Corrosion test of Zr alloy consisting of quenching and tempering Zry-2,Zry-4 cast, Zr-1% Nb cast, has been. conducted. In corrosion test, thechanges during ?-quenching, tempering and corrosion test at varioustemperature and time in autoclave water medium, can be seen. The treatmentconsisted of heating at 1050 oC for 30 minutes, quenching in water andtempering at 200 oC, 300 oC, 400 oC, 500 oC, 600 oC as well as corrosiontests at 225 oC, 275 oC, 325 oC at 4, 8, 12 hours. Sample preparation forcorrosion test was based on ASTM G-2 procedure, which consisted of washing,rinsing, pickling (3.5 cc HF 50%; 2.9 cc HNO3 65% and 57 cc AMB),neutralizing in 0.1 M Al(NO3)3, 9 H2O and ultrasonic rinsing/washing.Measurement performed are weight gain during corrosion, hardness test andmicrostructure observation using microscope optic. The results show that?-quenching of Zr alloy which was followed by tempering can turn ?martensite into tempered ?1martensit. The increase of temperingtemperature decreases the Zr alloy hardness and the lowest hardness ispossessed by Zr-1% Nb alloy. The corrosion test at 275 oC and 325 oC showsthat the weight gain depends on the tempering temperature, the temperingtemperature of 400 oC and 200 oC gives the maximum weight gain for Zry-2,Zry-4 cast, Zr-1% Nb. The largest number of hydride formed during corrosionis found in Zry-2, while the small one is in Zr-1% Nb. (author)

  4. Symptomatic stent cast.

    LENUS (Irish Health Repository)

    Keohane, John

    2012-02-03

    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.

  5. Casting thermal simulation

    International Nuclear Information System (INIS)

    The whole of this study is concerned with process simulation in casting processes. This study describes the application of the finite element method as an aid to simulating the thermal design of a high pressure die casting die by analysing the cooling transients in the casting cycle. Two types of investigation were carried out to model the linear and non-linear cooling behavior with consideration of a thermal interface effect. The simulated cooling for different stages were presented in temperature contour form. These illustrate the successful application of the Finite Element Method to model the process and they illustrate the significance of the thermal interface at low pressure

  6. Bainite obtaining in cast iron with carbides castings

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2010-01-01

    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.

  7. Bainite obtaining in cast iron with carbides castings

    OpenAIRE

    S. Pietrowski; G. Gumienny

    2010-01-01

    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.

  8. Bimetallic layered castings alloy steel – grey cast iron

    OpenAIRE

    Wro?bel, T.

    2011-01-01

    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...

  9. Aqueous Corrosion Characteristics of Nickel Aluminides

    International Nuclear Information System (INIS)

    The aqueous corrosion characteristics of three nickel aluminides were studied by using (a) immersion corrosion test and (b) cyclic anodic polarization measurements. The immersion tests were conducted in 15 different solutions at 25 .deg. C and 95 .deg. C. The nickel aluminides were found to have good corrosion resistance in inorganic acids, organic acids and basic solutions 25 .deg. C except at a higher concentration of hydrochloric acid in ferric chloride solution at the temperature. All three nickel aluminides were suitably resistant to corrosion in the organic acids (oxalic acid, acetic acid), sodium chloride solution, and bases (sodium hydoxide, ammonium hydroxide) at 95 .deg. C. The cyclic anodic polarization curves were developed in N2-deaerated solution at 25 .deg. C and 95 .deg. C. In addition, open-circuit corrosion potentials were determined for the solutions in the aerated condition at 25 .deg. C to compare with the anodic curves. At 25 .deg. C, although all materials exhibited active-passive behavior in all solutions except the hydrofluoric acid, at Ecorr(aerated), passive corrosion was only indicated for the acetic acid, sodium hydroxide, and sodium chloride solutions. Nevertheless, in all cases, the predicted dissolution rates were consistent with immersion test results. Hysteresis loops indicating susceptibility to localized corrosion were observed in 0.6M sodium chloride(pH=7) solution. At 95 .deg. C, active-passive behavior was demonstrated in the acetic acid, sodium chloride, and to a limited extent in the nitric acid: but only active behavior was shown in the sulfuric and hydrofluoric acids. From the above results, it was noted that anodic dissolution of nickel aluminides significantly increased with increasing temperature and that the Cr-containing compositions had better corrosion resistance in several solutions than the Cr-free composition. Prior manufacturing procedures, i.e., casting and powder metallurgy processes did not appear to influence the corrosion behavior of the nickel aluminides

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

    Directory of Open Access Journals (Sweden)

    Leszek A. Dobrza?ski

    2011-09-01

    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<.

  11. Corrosion resistance of neodymium composite materials reinforced with metal powders

    OpenAIRE

    M. Dzieko?ska; A. Zi?bowicz; B. Zi?bowicz; L.A. Dobrza?ski

    2012-01-01

    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 com...

  12. Evaluation on the corrosion of the three ni-cr alloys with different composition.

    Science.gov (United States)

    Rao, Srinivasa B; Chowdhary, Ramesh

    2011-01-01

    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, using potentiodynamic polarization method (electrochemical method) with fusayama artificial saliva as an electrolyte medium to check for their biocompatibility. The parameters for corrosion rate and corrosion resistance were obtained from computer-controlled corrosion schematic instrument, namely, potentiostat through corrosion software (power CV). The results obtained were analyzed by classic Tafel analysis. Statistical analysis was done by Student's t-test and ANOVA test. It was concluded that Dentarum and Bego showed satisfactory corrosive behavior, with exception of Sankin which depicted higher corrosion rate and least resistance to corrosion. Thus, the selection of an alloy should be made on the basis of corrosion resistance and biologic data from dental manufactures. PMID:21461232

  13. Centrifugal casting process

    International Nuclear Information System (INIS)

    Centrifugal casting is not one of the most common metalforming techniques, but there are a few applications of great value, for example in gas cooled reactors. In this article a few examples of these applications are discussed

  14. A new method of producing casts for anatomical studies.

    Science.gov (United States)

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

    2014-09-01

    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

  15. Method of casting aerogels

    Science.gov (United States)

    Poco, John F. (Livermore, CA)

    1993-01-01

    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.

  16. Seal welded cast iron nuclear waste container

    Science.gov (United States)

    Filippi, Arthur M. (Pittsburgh, PA); Sprecace, Richard P. (Murrysville, PA)

    1987-01-01

    This invention identifies methods and articles designed to circumvent metallurgical problems associated with hermetically closing an all cast iron nuclear waste package by welding. It involves welding nickel-carbon alloy inserts which are bonded to the mating plug and main body components of the package. The welding inserts might be bonded in place during casting of the package components. When the waste package closure weld is made, the most severe thermal effects of the process are restricted to the nickel-carbon insert material which is far better able to accommodate them than is cast iron. Use of nickel-carbon weld inserts should eliminate any need for pre-weld and post-weld heat treatments which are a problem to apply to nuclear waste packages. Although the waste package closure weld approach described results in a dissimilar metal combination, the relative surface area of nickel-to-iron, their electrochemical relationship, and the presence of graphite in both materials will act to prevent any galvanic corrosion problem.

  17. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Madhav Rao Gonvindaraju

    1999-10-18

    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.

  19. 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

  20. Corrosion Doctors

    Science.gov (United States)

    Corrosion Doctors

    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.

  1. Casting AISI 316 steel by gel cast

    International Nuclear Information System (INIS)

    The feasibility of producing AISI 316 steel components from their powders and avoiding their compaction is analyzed. A casting technique is tested that is similar to gel casting, used for ceramic materials. In the initial stage, the process consists of the formulation of a concentrated barbotine of powdered metal in a solution of water soluble organic monomers, which is cast in a mold and polymerized in situ to form a raw piece in the shape of the cavity. The process can be performed under controlled conditions using barbotines with a high monomer content from the acrylimide family. Then, the molded piece is slowly heated until the polymer is eliminated, and it is sintered at temperatures of 1160oC to 1300oC under a dry hydrogen atmosphere, until the desired densities are attained. The density and micro structure of the materials obtained are compared with those for the materials compacted and synthesized by the conventional processes. The preliminary results show the feasibility of the process for the production of certain kinds of structural components (CW)

  2. Plant Vascular Biology 2013: vascular trafficking.

    Science.gov (United States)

    Ursache, Robertas; Heo, Jung-Ok; Helariutta, Ykä

    2014-04-01

    About 200 researchers from around the world attended the Third International Conference on Plant Vascular Biology (PVB 2013) held in July 2013 at the Rantapuisto Conference Center, in Helsinki, Finland (http://www.pvb2013.org). The plant vascular system, which connects every organ in the mature plant, continues to attract the interest of researchers representing a wide range of disciplines, including development, physiology, systems biology, and computational biology. At the meeting, participants discussed the latest research advances in vascular development, long- and short-distance vascular transport and long-distance signalling in plant defence, in addition to providing a context for how these studies intersect with each other. The meeting provided an opportunity for researchers working across a broad range of fields to share ideas and to discuss future directions in the expanding field of vascular biology. In this report, the latest advances in understanding the mechanism of vascular trafficking presented at the meeting have been summarized. PMID:24431156

  3. Streptococcus mutans attachment on a cast titanium surface

    Directory of Open Access Journals (Sweden)

    Sicknan Soares da Rocha

    2009-03-01

    Full Text Available 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.

  4. Streptococcus mutans attachment on a cast titanium surface

    Scientific Electronic Library Online (English)

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

    2009-03-01

    Full Text Available 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.

  5. 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)

    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

    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.

  6. 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

  7. On Potentials of Ferrous Electrodes in Soil Corrosion Cells

    Directory of Open Access Journals (Sweden)

    B. N. Tripathi

    1966-04-01

    Full Text Available Open circuit potentials of electrodes and short circuit of soil corrosion cells constituted by cast iron, mild steel and wrought iron electrodes in the typical Indian soils have been determined and the voltages and the internal resistances of the cells have been calculated. The electrode potentials do not have a simple correlation with any of the soil properties. In non-acidic soils, the cell voltage at first increases abruptly with moisture equivalent, reaches maximum at about 15 and then decreases gradually. Based on this an interpretation has been offered for the maximum corrosivity of soils, having moisture equivalent, 30, as observed for mild steel and wrought iron. In an acidic soil electrode potentials of all the ferrous metals are indentical and cell voltages, very small. Hence most of the corrosion proceeds through direct chemical reaction. Cast iron is slightly less corrodible than mild steel and wrought iron because of additional protective influence of liberated carbon deposited over the metal.

  8. 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

  9. Corrosion behavior of Mg–2.4Zn alloy micro-alloyed with Ag and Ca

    International Nuclear Information System (INIS)

    Highlights: •Corrosion of four new cast Mg–Zn alloys in NaCl solution is carried out. •Effect of alloying addition (Ag, Ca, Ag + Ca) and ageing on corrosion is studied. •Size and distribution of precipitates play major role in corrosion. •Ca-containing alloys show good corrosion resistance. •Carbonate layer imparts good corrosion resistance to ZX60 and ZQX600 alloy. -- Abstract: The corrosion behavior of few cast Mg–Zn alloys, micro-alloyed with Ag and/or Ca (0.1 at.% each), has been investigated in 3.5 wt.% NaCl solution with the help of dynamic polarization, electrochemical impedance spectroscopy, and immersion tests. The effect of microstructures on corrosion behavior has been discussed thoroughly. The corrosion products formed on the immersed samples have been characterized by X-ray diffraction and Fourier transformed infrared spectroscopy. It has been observed that the Ca containing alloys show good corrosion resistance. This is attributed to the particular microstructure and carbonate-based protective film (corrosion products) formed on the surface

  10. Laser Vascular Lesion Treatment

    Science.gov (United States)

    ... Blood vessels on and around a nose before laser treatment for vascular lesions (in this instance, by a ... above, can reduce the risk of bruising. Alternatives Laser treatment is usually the best option for vascular lesions ...

  11. Society for Vascular Medicine

    Science.gov (United States)

    ... story in tweets! Patient Information Pages from Vascular Medicine June 2015 Raynaud's Phenomenon More info for patients. ... 1, 2014 Archive Submit a Case New! Vascular Medicine Videos Dr. Bruce Gray talks about his article, ...

  12. Heart and vascular services

    Science.gov (United States)

    ... branch of medicine that focuses on the cardiovascular system. ... Circulatory system; Vascular system; Cardiovascular system ... to diagnose, monitor or treat diseases of the circulatory and vascular system include: Cardiac CT for calcium scoring Cardiac MRI ...

  13. Effect of heat treatment on corrosion resistance of WE54 alloy

    Directory of Open Access Journals (Sweden)

    T. Rzycho?

    2007-01-01

    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.

  14. Casting Characteristics of Aluminum Die Casting Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    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.

  15. 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

  16. Scheduled Caste Women: Problems And Challenges

    OpenAIRE

    Vijayakumar Murthy; Jaikishan Thakur

    2013-01-01

    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...

  17. 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

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

    Directory of Open Access Journals (Sweden)

    Chaturvedi T

    2009-01-01

    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.

  19. Corrosion resistance of Mg-RE-Zr alloys

    Directory of Open Access Journals (Sweden)

    A. Kie?bus

    2007-03-01

    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.

  20. Evaluation of an improved centrifugal casting machine.

    Science.gov (United States)

    Donovan, T E; White, L E

    1985-05-01

    A Type III gold alloy, a silver-palladium alloy, and a base metal alloy were cast in two different centrifugal casting machines. With the number of complete cast mesh squares as an indicator of castability, the Airspin casting machine produced superior castings with all three alloys. The base metal alloy produced the greatest number of complete squares with both casting machines. PMID:3889295

  1. Wear resistance of cast iron

    OpenAIRE

    S. Pietrowski; G. Gumienny

    2008-01-01

    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.

  2. Bimetallic layered castings alloy steel – carbon cast steel

    OpenAIRE

    T. Wróbel; M. Cholewa; S. Tenerowicz

    2011-01-01

    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...

  3. Pipe Lines – External Corrosion

    OpenAIRE

    Dan Babor

    2008-01-01

    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...

  4. Electroradiography of cast products

    International Nuclear Information System (INIS)

    Technique for X-ray radiography of cast products of complex configuration of ferrous and non-ferrous metals and their alloys using control action of electric field on electroradiographic plate photoreceptor are described. Flaw detector based on application of this technique is suggested. Results of investigation of optimal test conditions for St.3 steel and duralumin are presented

  5. Thrombin and vascular inflammation.

    Science.gov (United States)

    Popovi?, Milan; Smiljani?, Katarina; Dobutovi?, Branislava; Syrovets, Tatiana; Simmet, Thomas; Isenovi?, Esma R

    2012-01-01

    Vascular endothelium is a key regulator of homeostasis. In physiological conditions it mediates vascular dilatation, prevents platelet adhesion, and inhibits thrombin generation. However, endothelial dysfunction caused by physical injury of the vascular wall, for example during balloon angioplasty, acute or chronic inflammation, such as in atherothrombosis, creates a proinflammatory environment which supports leukocyte transmigration toward inflammatory sites. At the same time, the dysfunction promotes thrombin generation, fibrin deposition, and coagulation. The serine protease thrombin plays a pivotal role in the coagulation cascade. However, thrombin is not only the key effector of coagulation cascade; it also plays a significant role in inflammatory diseases. It shows an array of effects on endothelial cells, vascular smooth muscle cells, monocytes, and platelets, all of which participate in the vascular pathophysiology such as atherothrombosis. Therefore, thrombin can be considered as an important modulatory molecule of vascular homeostasis. This review summarizes the existing evidence on the role of thrombin in vascular inflammation. PMID:21858738

  6. Automatic inspection of surface defects in die castings after machining

    Directory of Open Access Journals (Sweden)

    S. J. ?wi??o

    2011-07-01

    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.

  7. 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

  8. 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)

  9. The vascular endothelium / El endotelio vascular

    Scientific Electronic Library Online (English)

    Salvador, Moncada.

    2014-10-01

    Full Text Available 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.

  10. 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

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

    Directory of Open Access Journals (Sweden)

    L.A. Dobrza?ski

    2011-01-01

    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.

  12. Cast iron - a predictable material

    Directory of Open Access Journals (Sweden)

    Jorg C. Sturm

    2011-02-01

    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.

  13. Corrosion-resistant nickel-base alloys for gas turbines

    International Nuclear Information System (INIS)

    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

  14. Corrosion resistance of Elektron 21 magnesium alloy

    Directory of Open Access Journals (Sweden)

    A. Kie?bus

    2007-05-01

    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.

  15. [Casting faults and structural studies on bonded alloys comparing centrifugal castings and vacuum pressure castings].

    Science.gov (United States)

    Fuchs, P; Küfmann, W

    1978-07-01

    The casting processes in use today such as centrifugal casting and vacuum pressure casting were compared with one another. An effort was made to answer the question whether the occurrence of shrink cavities and the mean diameter of the grain of the alloy is dependent on the method of casting. 80 crowns were made by both processes from the baked alloys Degudent Universal, Degudent N and the trial alloy 4437 of the firm Degusa. Slice sections were examined for macro and micro-porosity and the structural appearance was evaluated by linear analysis. Statistical analysis showed that casting faults and casting structure is independent of the method used and their causes must be found in the conditions of casting and the composition of the alloy. PMID:352670

  16. CASTE CONFLICTAND WOMEN VICTIMS

    Directory of Open Access Journals (Sweden)

    V. Natchathira Selvakumari

    2015-01-01

    Full Text Available Communalism as a concept or theoretical construction is used to refer to section of the population differentiated by religion or caste. In the concise Oxford Dictionarycommunalism is defined as “The antagonistic religious and social communities in a district. Communal riot was a sudden and spasmodic incident. It was an aspect of socialpathology and its causation either in prevalence of a communal atmosphere generated by religious feelings or caste feelings. It could be effectively handled by efficient administrative or police action and secular public opinion. Communal riot is a struggle of values of claims to status power and scarce resources, in which the aims of the conflicting parties are not only to gain desired values but also to neutralize or injure or eliminate their rivals.

  17. Regulation of Vascular Integrity

    OpenAIRE

    Murakami, Masahiro; Simons, Michael

    2009-01-01

    The integrity of blood vessels is critical to vascular homeostasis. Maintenance of vascular integrity has been conventionally regarded as a passive process that is largely dependent on continuous blood flow. Recent studies, however, have begun unveiling molecular processes essential for maintenance of vascular integrity and homeostasis under physiological conditions, leading to the notion that maintenance of the vasculature is an active biological process that requires continuous, basal cellu...

  18. Bimetallic layered castings alloy steel – carbon cast steel

    Directory of Open Access Journals (Sweden)

    T. Wróbel

    2011-01-01

    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.

  19. Zinc-The key to preventing corrosion

    Science.gov (United States)

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

    2011-01-01

    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.

  20. Contemporary art casting’s education in Guangdong

    OpenAIRE

    Wu Chunmiao; Ji Qing

    2012-01-01

    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...

  1. 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

  2. Roles of ? phase in the corrosion process of AZ91D magnesium alloy

    International Nuclear Information System (INIS)

    For better understanding of the roles of ? phase in the corrosion processes of AZ91D alloy, corrosion behavior of a cast (? + ? phase) and a homogenized (? phase) AZ91D alloy was investigated in NaCl aqueous solution by gas collection and electrochemical measurements. According to the hydrogen evolution properties during corrosion, two different types of corrosion tend might be differentiated. For type I, hydrogen diffused into alloy, which evoked the decreasing of hydrogen evolution rate (HER) and the weakening of negative difference effect (NDE). For type II, in the corrosion process, hydrogen in the alloys diffused into the product film (P-type semiconductor), which suggested that hydrogen entering the film would be ionized. The generated electrons during ionization decreased the concentration of vacancies in the valence band of the product films, indicating an improvement of corrosion resistance of AZ91D alloy

  3. Corrosion test of structural materials for thermo-chemical and electrolytic hybrid hydrogen production cycle

    International Nuclear Information System (INIS)

    Corrosion behavior of structural materials for thermo-chemical and electrolytic hydrogen production cycle was investigated in liquid and gaseous sulfuric acid in the temperature range of 200-500degC. The cycle is one of the hydrogen production methods using sulfuric acid and the maximum temperature through the processes is about 500degC. In this study, corrosion tests of candidate structural materials for equipment of the hydrogen production plant were performed at the conditions each equipment will be used. The concentration of sulfuric acid was 95 mass% in all experiments and maximum test duration was 500 h. Only high Si cast iron had good corrosion resistance in the boiling sulfuric acid, whereas high Si cast iron and Hastelloy C276 had good corrosion resistance in the sulfurous acid gas atmosphere (vaporized sulfuric acid or mixture of sulfur dioxide and water vapor). Furthermore, post test analysis by optical microscope and SEM-EDX were performed. (author)

  4. 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

  5. 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

  6. Corrosion inhibiting organic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Sasson, E.

    1984-10-16

    A corrosion inhibiting coating comprises a mixture of waxes, petroleum jelly, a hardener and a solvent. In particular, a corrosion inhibiting coating comprises candelilla wax, carnauba wax, microcrystalline waxes, white petrolatum, an oleoresin, lanolin and a solvent.

  7. Modelling of Corrosion Cracks

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    2003-01-01

    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.

  8. Duralumin and Its Corrosion

    Science.gov (United States)

    Nelson, WM

    1927-01-01

    The types of corrosion and factors of corrosion of duralumin are investigated. Salt water is the most common of the corroding media with which designers have to contend in using duralumin in aircraft and ships.

  9. Localized corrosion information using high resolution measurement devices

    DEFF Research Database (Denmark)

    Ambat, Rajan

    2005-01-01

    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.

  10. Surface properties and corrosion behavior of Co-Cr alloy fabricated with selective laser melting technique.

    Science.gov (United States)

    Xin, Xian-zhen; Chen, Jie; Xiang, Nan; Wei, Bin

    2013-01-01

    We sought to study the corrosion behavior and surface properties of a commercial cobalt-chromium (Co-Cr) alloy which was fabricated with selective laser melting (SLM) technique. For this purpose, specimens were fabricated using different techniques, such as SLM system and casting methods. Surface hardness testing, microstructure observation, surface analysis using X-ray photoelectron spectroscopy (XPS) and electrochemical corrosion test were carried out to evaluate the corrosion properties and surface properties of the specimens. We found that microstructure of SLM specimens was more homogeneous than that of cast specimens. The mean surface hardness values of SLM and cast specimens were 458.3 and 384.8, respectively; SLM specimens showed higher values than cast ones in hardness. Both specimens exhibited no differences in their electrochemical corrosion properties in the artificial saliva through potentiodynamic curves and EIS, and no significant difference via XPS. Therefore, we concluded that within the scope of this study, SLM-fabricated restorations revealed good surface properties, such as proper hardness, homogeneous microstructure, and also showed sufficient corrosion resistance which could meet the needs of dental clinics. PMID:23553145

  11. Fracture Mechanisms in Steel Castings

    Directory of Open Access Journals (Sweden)

    Z. Stradomski

    2013-07-01

    Full Text Available 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 the net of secondary cementite and/or ledeburite precipitated along the boundaries of solidified grains. Also the brittle phosphor and carbide eutectics precipitated in the final stage solidification are responsible for cracking of castings made of Hadfield steel. The examination of mechanical properties at 1050°C revealed low or very low strength of high-carbon cast steels.

  12. 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)

  13. Metal Casting- A Review Work

    OpenAIRE

    Haider Hussain

    2014-01-01

    This paper deals about the trends of Al/Al alloys based metal casting . It reviews the historical events of metal matrix composites (MMCs), produced in casting industries. After a brief introduction on properties of metal matrix composites. Processing and the developments of the metal matrix composites have been discussed at length. On the basis of above said subject, the future research needs in metal matrix composites on the basis of applications of the casting in industry w...

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

    Directory of Open Access Journals (Sweden)

    K Nirmalkumar

    2009-02-01

    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. 

  15. Management of Reinforcement Corrosion

    DEFF Research Database (Denmark)

    Küter, André; Geiker, Mette Rica

    Reinforcement corrosion is the most important cause for deterioration of reinforced concrete structures, both with regard to costs and consequences. Thermodynamically consistent descriptions of corrosion mechanisms are expected to allow the development of innovative concepts for the management of reinforcement corrosion.

  16. Organic corrosion inhibitors

    International Nuclear Information System (INIS)

    Adsorption of organic compounds on metallic electrodes is one of the main ways for its corrosion inhibition. The different classifications of corrosion inhibitors have been reviewed. Moreover, the most important factors in the action of organic corrosion inhibitors, metal charge surface and inhibitor structure are studied. From this, it is possible to propose the mechanisms of the inhibition. (author)

  17. Development of Lead-Free Copper Alloy-Graphite Castings

    Energy Technology Data Exchange (ETDEWEB)

    Rohatgi, P.K. [Univ. of Wisconsin-Milwaukee (US)

    1999-10-01

    In this project, graphite is used as a substitute for lead in order to maintain the machinability of plumbing components at the level of leaded brass. Graphite dispersed in Cu alloy was observed to impart good machinability and reduce the sizes of chips during machining of plumbing components in a manner similar to lead. Copper alloys containing dispersed graphite particles could be successfully cast in several plumbing fixtures which exhibited acceptable corrosion rate, solderability, platability, and pressure tightness. The power consumption for machining of composites was also lower than that of the matrix alloy. In addition, centrifugally cast copper alloy cylinders containing graphite particles were successfully made. These cylinders can therefore be used for bearing applications, as substitutes for lead-containing copper alloys. The results indicate that copper graphite alloys developed under this DOE project have a great potential to substitute for lead copper alloys in both plumbing and bearing applications.

  18. Poikiloderma vasculare atrophicans

    Directory of Open Access Journals (Sweden)

    Padmavathy L

    1994-01-01

    Full Text Available A 65 year old lady presented with generalised pruritus and discolouration of skin and mucous membranes of 5 years duration. The histopathology from the cutaneous lesions revealed features suggestive of poikiloderma vasculare atrophicans (PVA. Investigations did not reveal any underlying connective tissue disease,lymphoma or systemic disease. A diagnosis of idiopathic poikiloderma vasculare atrophicans was made.

  19. Vascular Intracranial Hypertension

    OpenAIRE

    Iencean, S. M.

    2004-01-01

    Intracranial hypertension is one of the most important syndromes in neurology and neurosurgery; raised intracranial pressure is the most common cause of death in neurosurgery. A recent classification of intracranial hypertension is based upon the etiopathogenesis of intracranial hypertension: a) parenchymatous intracranial hypertension, b) vascular intracranial hypertension, c) meningeal intracranial hypertension and d) idiopathic intracranial hypertension. Vascular etiologies can individuali...

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

    Science.gov (United States)

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

    2014-12-10

    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

  1. Fracture Mechanisms in Steel Castings

    OpenAIRE

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

    2013-01-01

    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 ...

  2. Skeleton castings dynamic load resistance

    Directory of Open Access Journals (Sweden)

    M. Cholewa

    2013-06-01

    Full Text Available Purpose: The article is to show selected results of research in a field of new type of cast spatial composite reinforcements. This article shows skeleton casting case as a particular approach to continuous, spatial composite reinforcement.Design/methodology/approach: The research is concerning properties of cast spatial microlattice structures called skeleton castings. In this paper results of impact test of skeleton casting with octahedron elementary cell were shown. The selection of internal topology of skeleton casting was based on numerical simulations of stress distribution.Findings: The possibility of manufacturing of geometrically complex skeleton castings without use of advanced techniques was confirmed.Research limitations/implications: With use of computer tomography, analysis of deformation mechanisms was carried out. Different levels of impact energies were usedPractical implications: Spatial skeleton casting with octahedron elementary cell confirmed their usefulness as impact energy absorbers.Originality/value: The overall aim of presented research was to determine the mechanisms of skeleton castings deformation processes. Thanks to CT data next step will be to create accurate numerical model for further simulation and design optimization.

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

    OpenAIRE

    J. Stradomska

    2009-01-01

    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...

  4. Phase transformations in cast duplex stainless steels

    Science.gov (United States)

    Kim, Yoon-Jun

    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.

  5. Development of EPR technique for the control of cast alloys

    International Nuclear Information System (INIS)

    The EPR DL (electrochemical potentiokinetic reactivation double loop) technique enables the detection and quantification of de-chromed areas in stainless steel materials. This dechromisation results in a local destruction of the passive film around the chrome carbides or the intermetallic chrome-based phases (phases ?, ?..). The conjunction of a corrosive mixture and chrome-depleted areas gives rise to an intergranular corrosion phenomenon (IC). This work sums up the design of testing conditions for the EPR test with a view to controlling in situ the structure of cast materials. We searched for a sensitive enough electrolyte, as well as for operational conditions leading to an easy application on site. The study was carried out with two alloys: - austenitic stainless steel CN-7M - nickel based passivable alloy CW-12MW and was accompanied with the development of a portable EPR cell for in-situ testing. (orig.)

  6. Colour Metallography of Cast Iron - White Cast Iron (?

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2011-11-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2011-08-01

    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.

  8. Scheduled Caste Women: Problems And Challenges

    Directory of Open Access Journals (Sweden)

    Vijayakumar Murthy

    2013-12-01

    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.

  9. DEGRADATION WORKS OF MONUMENTAL ART CAST BRONZE UNDER THE INFLUENCE OF ENVIRONMENTAL FACTORS

    Directory of Open Access Journals (Sweden)

    Delia NICA-BADEA

    2012-11-01

    Full Text Available Intensive pollution, combined with the lack of conservation of monuments exposed to these environments make the main cause of deterioration of cultural objects to atmospheric corrosion metal. This paper proposes a study of the main factors leading to degradation Bronze alloy, cast bronze monuments exposed to open atmosphere: corrosive environmental factors, stability and products of corrosion of bronze. In general, all corrosion products present on a metal surface are indicated as 'skate', can be composed of single-layer or multilayer products. The paper also includes a case study on the influence of environmental factors on degradation Matthias monument statue in Cluj-Napoca, Romania. Visual inspection of the monument informs us that have white spots, gray, reddish not consistent with the base color green patina, surfaces showing depigmentation, the rain washed areas, crystallization, deposition of air-borne particles.

  10. Vascular Access in Children

    International Nuclear Information System (INIS)

    Establishment of stable vascular access is one of the essential and most challenging procedures in a pediatric hospital. Many clinical specialties provide vascular service in a pediatric hospital. At the top of the “expert procedural pyramid” is the pediatric interventional radiologist, who is best suited and trained to deliver this service. Growing awareness regarding the safety and high success rate of vascular access using image guidance has led to increased demand from clinicians to provide around-the-clock vascular access service by pediatric interventional radiologists. Hence, the success of a vascular access program, with the pediatric interventional radiologist as the key provider, is challenging, and a coordinated multidisciplinary team effort is essential for success. However, there are few dedicated pediatric interventional radiologists across the globe, and also only a couple of training programs exist for pediatric interventions. This article gives an overview of the technical aspects of pediatric vascular access and provides useful tips for obtaining vascular access in children safely and successfully using image guidance.

  11. Education and Caste in India

    Science.gov (United States)

    Chauhan, Chandra Pal Singh

    2008-01-01

    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…

  12. 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)

  13. Colour Metallography of Cast Iron

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2009-05-01

    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.

  14. 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

  15. Corrosion principles and surface modification

    International Nuclear Information System (INIS)

    This chapter examines the important strategies provided by the newer ideas of corrosion science and engineering that surface modification techniques must utilize to help prevent corrosion, especially the most damaging kind of aqueous corrosion, localized corrosion. Provides a brief introduction to the principles underlying the phenomenon of corrosion in order to use them to discuss surface modification strategies to combat corrosion. Discusses the electrochemistry of corrosion; the thermodynamics of corrosion; the kinetics of corrosion; thermodynamic strategies; and kinetic strategies (formation of more protective passive films; resistance to breakdown; ductility; repassivation)

  16. 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)

  17. Long term stability analysis of cast iron shaft linings after Coal Mine closure and flooding

    International Nuclear Information System (INIS)

    This paper presents the results of a study conducted to analyse the long term stability of the cast iron shaft lining after coal mine closure and flooding. The attention is mainly focused on the behaviour during the critical phase of flooding as well as the phase corresponding to the disappearance of the water pressure and the stabilization of the environment. This pluri-disciplinary study was conducted by a team combining specialists in rock mechanics who identified the main risks and the conditions of stability of the lining and specialists in metallurgy who studied the composition of the cast iron and its corrosion behaviour after exposure to mine water. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-30

    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.

  19. Influence of mictrostructure features on the corrosion behaviourof AZ91 alloy in chloride media

    Directory of Open Access Journals (Sweden)

    Lenka Bukovinová

    2014-11-01

    Full Text Available The influence of the microstructure of as-cast AZ91 magnesium alloy, which applied to solution annealing treatment and ageing treatment respectively, was evaluated in terms of its corrosion behaviour in 0.1 M NaCl solution at room temperature. The corrosion process was monitored by electrochemical impedance spectroscopy (EIS and the surface was characterized by scanning Kelvin probe force microscopy (SKPFM. The extent of corrosion damage was dependent on the microstructure. Surface potential maps indicated that, the surface potential of ?-matrix is more positive than surface potential of ? phase.

  20. Sinuosities in vascular structures

    Science.gov (United States)

    Masson, J.-B.; Martin, J.-L.

    2007-12-01

    In most organs, depending on the scale, the nature of the heart pump, the geometry and topology of the organ, some of the blood vessels tend to exhibit sinuous trajectories. We describe a part of this sinuous behavior, including partial biological and strong physical effects in a global physical framework. We will voluntarily focus on physical and topological effects. This study is performed on the vitelline membrane of the chicken embryo. Crossing angles, sinuosity, and the oscillation amplitude of the vascular system are analyzed. Surprisingly, the equation of river meandering dynamics is found to model the sinuosities in the vascular system, and an extension of this equation to non planar case is able to explain the effect of tissue global curvature on the vascular system. Results of this study could lead to a new understanding of the interplay between biological signaling and physical effects in determining the vascular pattern in different tissues.

  1. Vascular Access for Hemodialysis

    Science.gov (United States)

    ... an infection, or a scarred vein, causing the vein to narrow. However, if a patient needs to start hemodialysis ... an infection, or a scarred vein, causing the vein to narrow. All three types of vascular access can cause ...

  2. Vascular Hyperpermeability and Aging

    OpenAIRE

    Oakley, Ryan; Tharakan, Binu

    2014-01-01

    Vascular hyperpermeability, the excessive leakage of fluid and proteins from blood vessels to the interstitial space, commonly occurs in traumatic and ischemic injuries. This hyperpermeability causes tissue vasogenic edema, which often leads to multiple organ failure resulting in patient death. Vascular hyperpermeability occurs most readily in small blood vessels as their more delicate physical constitution makes them an easy target for barrier dysfunction. A single layer of endothelial cells...

  3. Vascular alterations in schwannoma

    OpenAIRE

    Papiez, Joseph; Rojiani, Mumtaz V; Rojiani, Amyn M.

    2014-01-01

    Schwannomas or neurilemmoma are benign peripheral nerve sheath tumors, which most frequently occur at the cerebellopontine angle. This morphologic study examines vascular alterations in these tumors, comparing them to other benign spindle cell neoplasms of the nervous system, while correlating these findings with evidence of vascular permeability. Thirty-four nervous system spindle cell neoplasms, sixteen schwannomas, nine fibroblastic/transitional meningiomas and nine peripheral neurofibroma...

  4. 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.)

  5. The vascular system

    International Nuclear Information System (INIS)

    MRI has enormous potential for evaluating the vascular system. A number of important clinical uses are already evident, and most are described in this chapter. Research proceeds to develop the technique in a quantitative direction in an effort to provide a noninvasive method for measuring flow and perfusion. It is likely that the current uses of MRI in the vascular system represent the tip of the iceberg

  6. Vascular Lumen Formation

    OpenAIRE

    Lammert, Eckhard; Axnick, Jennifer

    2012-01-01

    The vascular system developed early in evolution. It is required in large multicellular organisms for the transport of nutrients, oxygen, and waste products to and from tissues. The vascular system is composed of hollow tubes, which have a high level of complexity in vertebrates. Vasculogenesis describes the de novo formation of blood vessels, e.g., aorta formation in vertebrate embryogenesis. In contrast, angiogenesis is the formation of blood vessels from preexisting ones, e.g., sprouting o...

  7. Vascularizing the heart.

    OpenAIRE

    Riley, Pr; Smart, N.

    2011-01-01

    As the developing heart grows and the chamber walls thicken, passive diffusion of oxygen and nutrients is replaced by a vascular plexus which remodels and expands to form a mature coronary vascular system. The coronary arteries and veins ensure the continued development of the heart and facilitate cardiac output with progression towards birth. Many aspects of coronary vessel development are surprisingly not well understood and recently there has been much debate surrounding both the developme...

  8. Casting process modeling using ProCAST and CAST2D

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, A.; Stein, W.; Raboin, P.

    1990-12-01

    Correctly modeling the fluid flow and heat transfer during the filling of a mold with a molten metal, and the thermal-mechanical physics of solidification and cooldown is important in predicting the quality of a cast part. Determining the dynamics of the flow and the free surface shape during filling are essential in establishing the temperature gradients in the melt and in the mold. Correctly modeling the physics of volume change on solidification, shrinkage on cooling, and contact resistance across the part-mold interface directly affects the cooling rate and ultimately the final cast shape and stress state of the cast part. In this paper we describe our current research efforts on modeling fluid fill using the commercial code ProCAST by UES, and thermal-mechanical solidification modeling using the code CAST2D by LLNL.

  9. On the corrosion of binary magnesium-rare earth alloys

    International Nuclear Information System (INIS)

    The corrosion properties of high-pressure die cast (HPDC) magnesium-rare earth (RE) based alloys have been studied. Binary additions of La, Ce and Nd to commercially pure Mg were made up to a nominal 6 wt.%. It was found that the intermetallic phases formed in the eutectic were Mg12La, Mg12Ce and Mg3Nd, respectively. Results indicated that increasing RE alloying additions systematically increased corrosion rates. This was also described in the context of the electrochemical response of Mg-RE intermetallics - which were independently assessed by the electrochemical microcapillary technique. This study is a discrete effort towards revealing the electrochemical effect of carefully controlled binary alloying additions to magnesium in order to elucidate the microstructure-corrosion relationship more generally for HPDC Mg alloys. Such fundamental information is seen to not only be useful in understanding the corrosion of alloys which presently contain RE additions, but may be exploited in the design of magnesium alloys with more predictable corrosion behaviour. There is a special need to understand this relationship - particularly for magnesium that commonly displays poor corrosion resistance

  10. 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)

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

    DEFF Research Database (Denmark)

    Santos, Tatiana Carlesso; Oliveira, Moacir Franco

    2012-01-01

    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.

  12. Pipe Lines – External Corrosion

    Directory of Open Access Journals (Sweden)

    Dan Babor

    2008-01-01

    Full Text Available 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 range, which is seen from the varying electrical conductivity and pH (varies between 3 and 10. Therefore the characteristics of a soil will be an important factor in under-ground corrosion.

  13. Incidence of ZrO2 on the physical chemical properties at high temperatures of cast powder

    International Nuclear Information System (INIS)

    The cast powders normally used in the continuous casting process in many steel mills contain a great number of oxides. The chemical composition of these materials determines the behavior of the powders in operating conditions and their corrosive effect on the submerged dips. Specifically, these powders require certain levels of fluidity in order to guarantee lubrication in the cast. No less important is the tendency to crystallization due to the formation of crystalline phases in the layer of cast powder during cooling, since the proportion of crystalline phases influences the cast's heat extraction conditions. Another aspect to be aware of is that industrial production requirements demand greater availability of the equipment and, therefore, prolonging the duration of the dipping is of considerable interest. An understanding of the phenomena in the processing conditions should start with a knowledge of the effects of the variations in the chemical composition of these powders. This work presents the influence of the added zircon oxide (ZrO2) on the fluidity and crystallization of commercial cast powders. Fluidity tests were performed with the sloped plane method and with micro-structural observations of these samples in order to observe their degree of crystallization. Corrosion tests were carried out to know what attack mechanisms are used on the dips. According to the results, the addition of zircon oxide causes an increase in both the viscosity and the an increase in both the viscosity and the proportion of crystals. So the potential addition of this oxide in the commercial powders, as an innovation in the steel company's operating practices, would cause less heat extraction from the cast steel and a lower level of lubrication. Maintaining the current processing conditions (casting speed, flow of refrigeration water, etc.) could produce serious disorder in the process and in the quality of the final product. Considering just the aspect of durability of the aluminum-graphite dips, the corrosion trials performed at 1200 oC, indicate that the speed of corrosion of the dip drops with the addition of ZrO2 in the powder. However, micro-structural observations of the attacked zones, show that the mechanisms operating during this corrosion process are the same ones that operate in the cast powder without zircon (cw)

  14. Modelling the corrosion-induced cracking of reinforced concrete structures exposed to the atmosphere

    International Nuclear Information System (INIS)

    The prediction of concrete cracking due to corrosion in atmospheric/carbonated conditions is a major issue for the evaluation of the durability of structures and the choice of maintenance policies. Because of the complexity of the phenomenon, a fully predictive approach is still missing. The proposed work can be considered as one step in this direction. It deals with a modelling study achieved at the Commissariat a l'Energie Atomique (CEA) with the CAST3M finite elements software. Model is constituted of three components: (1) concrete hydric behaviour, (2) rebar corrosion and (3) mechanical consequences on concrete (mainly concrete cracking). Actual developments consider analogies between rebar corrosion mechanisms and atmospheric corrosion ones, assuming that corrosion processes are influenced by the relative humidity evolution of atmosphere and/or of concrete. (authors)

  15. Colour Metallography of Cast Iron - White Cast Iron (?)

    OpenAIRE

    Zhou Jiyang

    2011-01-01

    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 ...

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

    OpenAIRE

    Zhou Jiyang

    2011-01-01

    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 ...

  17. 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

  18. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-10-15

    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.

  20. Automated Methods Of Corrosion Measurements

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers; Andersen, Jens Enevold Thaulov

    1997-01-01

    The chapter describes the following automated measurements: Corrosion Measurements by Titration, Imaging Corrosion by Scanning Probe Microscopy, Critical Pitting Temperature and Application of the Electrochemical Hydrogen Permeation Cell.

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

    Directory of Open Access Journals (Sweden)

    J. Stradomska

    2009-07-01

    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.

  2. 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

  3. Prefabrication of axial vascularized tissue engineering coral bone by an arteriovenous loop: A better model

    Energy Technology Data Exchange (ETDEWEB)

    Dong Qingshan [Department of Oral and Maxillofacial Surgery, Wuhan General Hospital of Guangzhou Military Command, Wuhan 430070 (China); Shang Hongtao; Wu Wei [Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Chen Fulin [Lab of Tissue Engineering, Faculty of Life Science, Northwest University, Xi' an 710069 (China); Zhang Junrui [Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Guo Jiaping [Department of Oral and Maxillofacial Surgery, Wuhan General Hospital of Guangzhou Military Command, Wuhan 430070 (China); Mao Tianqiu, E-mail: tianqiumao@126.com [Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China)

    2012-08-01

    The most important problem for the survival of thick 3-dimensional tissues is the lack of vascularization in the context of bone tissue engineering. In this study, a modified arteriovenous loop (AVL) was developed to prefabricate an axial vascularized tissue engineering coral bone in rabbit, with comparison of the arteriovenous bundle (AVB) model. An arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. It was placed in a circular side groove of the coral block. The complex was wrapped with an expanded-polytetrafluoroethylene membrane and implanted beneath inguinal skin. After 2, 4, 6 and 8 weeks, the degree of vascularization was evaluated by India ink perfusion, histological examination, vascular casts, and scanning electron microscopy images of vascular endangium. Newly formed fibrous tissues and vasculature extended over the surfaces and invaded the interspaces of entire coral block. The new blood vessels robustly sprouted from the AVL. Those invaginated cavities in the vascular endangium from scanning electron microscopy indicated vessel's sprouted pores. Above indexes in AVL model are all superior to that in AVB model, indicating that the modified AVL model could more effectively develop vascularization in larger tissue engineering bone. - Highlights: Black-Right-Pointing-Pointer A modified arteriovenous loop (AVL) model in rabbit was developed in this study. Black-Right-Pointing-Pointer Axial prevascularization was induced in a larger coral block by using the AVL. Black-Right-Pointing-Pointer The prefabrication of axial vascularized coral bone is superior as vascular carrier.

  4. Prefabrication of axial vascularized tissue engineering coral bone by an arteriovenous loop: A better model

    International Nuclear Information System (INIS)

    The most important problem for the survival of thick 3-dimensional tissues is the lack of vascularization in the context of bone tissue engineering. In this study, a modified arteriovenous loop (AVL) was developed to prefabricate an axial vascularized tissue engineering coral bone in rabbit, with comparison of the arteriovenous bundle (AVB) model. An arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. It was placed in a circular side groove of the coral block. The complex was wrapped with an expanded-polytetrafluoroethylene membrane and implanted beneath inguinal skin. After 2, 4, 6 and 8 weeks, the degree of vascularization was evaluated by India ink perfusion, histological examination, vascular casts, and scanning electron microscopy images of vascular endangium. Newly formed fibrous tissues and vasculature extended over the surfaces and invaded the interspaces of entire coral block. The new blood vessels robustly sprouted from the AVL. Those invaginated cavities in the vascular endangium from scanning electron microscopy indicated vessel's sprouted pores. Above indexes in AVL model are all superior to that in AVB model, indicating that the modified AVL model could more effectively develop vascularization in larger tissue engineering bone. - Highlights: ? A modified arteriovenous loop (AVL) model in rabbit was developed in this study. ? Axial prevascularization was induced in a larger coral block by using the AVL. ? The coral block by using the AVL. ? The prefabrication of axial vascularized coral bone is superior as vascular carrier.

  5. Corrosion resistance of neodymium composite materials reinforced with metal powders

    Directory of Open Access Journals (Sweden)

    M. Dzieko?ska

    2012-12-01

    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.

  6. Study on plasma-spraying Ni-Al-WC alloy layer on the surface of chrome cast iron and alloy layer's micro-structure and properties

    International Nuclear Information System (INIS)

    Plasma-spraying Ni-Al-WC alloy layer on the surface of chrome cast iron and alloy layer's micro-structure and properties are studied. The analysis items include chemical composition, phase structure, average microhardness, wear resistance and corrosion resistance. The experimental results indicate that metallurgical combination has been achieved completely between the spraying layer and the surface of chrome cast iron, and that the chemical composition and micro-structure in the surface layer of the sample have been changed basically, and that the microhardness, the wear resistance, the corrosion resistance in the surface layer are increased by a large margin

  7. Colonization of ion-modified polyethylene with vascular smooth muscle cells in vitro.

    Czech Academy of Sciences Publication Activity Database

    Walachová, K.; Švor?ík, V.; Ba?áková, Lucie; Hnatowicz, Vladimír

    2002-01-01

    Ro?. 23, ?. 14 (2002), s. 2989-2996. ISSN 0142-9612 R&D Projects: GA AV ?R IAA7011908 Institutional research plan: CEZ:AV0Z5011922 Keywords : vascular smooth muscle cells * ion-implanted polyethylene -wettability Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 3.008, year: 2002

  8. Modelling of flow phenomena during DC casting:

    OpenAIRE

    Zuidema, J.

    2005-01-01

    Modelling of Flow Phenomena during DC Casting Jan Zuidema The production of aluminium ingots, by semi-continuous casting, is a complex process. DC Casting stands for direct chill casting. During this process liquid aluminium transforms to solid aluminium while cooling down. This is not an instantaneous transformation, but occurs in temperature interval. In the casting process the latent heat is moved away by convection and conduction. A number of problems may occur during solidification,...

  9. CASTE SYSTEMS IN INDIA: AN OVERVIEW

    OpenAIRE

    Amit Kumar; Lal Das, S. N.

    2014-01-01

    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...

  10. Inoculation of chromium white cast iron

    OpenAIRE

    D. Kopyci?ski

    2009-01-01

    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.

  11. Computer aided casting methoding of railway system

    Directory of Open Access Journals (Sweden)

    St. M. Dobosz

    2008-07-01

    Full Text Available Authors prepared the casting technology for the frog. Casting method has been verified by simulation, using MAGMASOFT technique. In multistep simulation it was found that the positioning of casting in the mould feeding and some details of construction must be changed. Finally authors have presented the optimised solution of the technology which eliminates the porosity of casting. Analyses of the distribution of the stress during solidification and cooling in the mould proves that the deformation of casting is acceptable.

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

    OpenAIRE

    Anju Ramesh; N. Saleem; N. M Najarajan

    2014-01-01

    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...

  13. Simultaneous oxidation and decarburization of cast iron powder during plasma spraying.

    Czech Academy of Sciences Publication Activity Database

    Voleník, Karel; Schneeweiss, Old?ich; Chráska, Tomáš; Dubský, Ji?í; Písa?ka, Jan

    2009-01-01

    Ro?. 47, ?. 1 (2009), s. 19-24. ISSN 0023-432X R&D Projects: GA AV ?R IAA1041404 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z20410507 Keywords : cast iron powder * plasma spraying * oxidation * decarburization Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.345, year: 2007 http://kovmat.sav.sk/ abstract .php?rr=47&cc=1&ss=19

  14. Some observations on the strength and fatigue properties of samples extracted from cast iron water mains

    OpenAIRE

    Belmonte, HMS; Mulheron, MJ; Smith, PA

    2009-01-01

    The strength and fatigue properties of cast iron samples taken from water distribution mains have been investigated. Specimens were sourced from three sections of pipe which had experienced varying amounts of corrosion in service, enabling the variable of pipe condition to be incorporated within the study. The strengths in four-point flexure of small specimens from the pipes examined were described using Weibull statistics; different characteristic strengths and Weibull moduli were obtained, ...

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

    OpenAIRE

    Kie?bus, A.

    2007-01-01

    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...

  16. Colour Metallography of Cast Iron

    OpenAIRE

    Zhou Jiyang

    2009-01-01

    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 ...

  17. Plaster cast burns: the reality.

    Science.gov (United States)

    Read, J A; Ferguson, N; Ricketts, D M

    2008-12-01

    An in vivo experimental study was performed of the temperatures produced by a setting plaster cast using hot and cold water. The results confirmed a statistical difference in the temperatures reached using hot and cold water. Forearm and below knee plasters did not represent a burn risk. Lower limb cylinder casts reached sufficient temperatures to cause burns with hot water but did not remain at these temperatures long enough to pose a clinical risk. PMID:19033502

  18. Evaluation of the corrosion resistance of plasma nitrided austenitic stainless steel

    International Nuclear Information System (INIS)

    Plasma nitriding at 500 C for 14 h was applied to austenitic 304 stainless steel for surface hardening. The effect of surface treatment on the corrosion resistance of the material was investigated in naturally-aerated 0.5 M NaCl solution for 30 days using linear potentiodynamic polarization and electrochemical impedance spectroscopy methods. Both as-cast and plasma nitrided stainless steel samples underwent spontaneous passivation, though the nitrided sample exhibited more positive zero current potential, higher breakdown potential, and lower anodic current densities than the as-cast material. Impedance spectra were interpreted in terms of a duplex passive film, corrosion resistance mainly arising from a thin inner compact layer, whereas the outer layer was more porous and less sealing. Capacitive behaviour and high corrosion resistance were observed in the low and medium frequency ranges for the nitrided samples.

  19. [Epithelioid vascular tumor].

    Science.gov (United States)

    Skuleti?, Vesna; Bokun, Radojka; Tatomirovi?, Zeljka; Popovi?, Lidija

    2002-01-01

    Epithelioid vascular tumors are neoplasms formed by endothelial cells, morphologically similar to epithelial cells. Morphological shape of the cells in this tumors varies from benign to malignant forms, causing the diverse biological potential of the tumors. This case-report presents immunophenotypically interesting epithelioid vascular tumor of the upper vena cava manifested in thrombotic complications. It is characterized by solid growth of tumor cells and the attempt of forming vascular channels. According to immunophenotype, tumor cells corresponded to endothelial cells with low proliferative potential and vasoformative capability of forming intracellular lumina. For that reason this tumor manifested similarity with epithelioid hemangioendothelioma. However, it differentiated from the hemangioendothelioma by benign cytomorphological characteristics of tumor cells, absence of pathological mitoses, more intensive inflammatory infiltrate with eosinophylia and good tissue control, of tumor growth because of the presence of pericites. According to histological features and histochemical analyses the diagnosis of this tumor was established as an intravascular, solid, epithelioid hemangioma. PMID:12852153

  20. Aluminum Corrosion and Turbidity

    International Nuclear Information System (INIS)

    Aluminum corrosion and turbidity formation in reactors correlate with fuel sheath temperature. To further substantiate this correlation, discharged fuel elements from R-3, P-2 and K-2 cycles were examined for extent of corrosion and evidence of breaking off of the oxide film. This report discusses this study

  1. 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.)

  2. Corrosion evaluation technology

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Uh Chul; Han, Jeong Ho; Nho, Kye Ho; Lee, Eun Hee; Kim, Hong Pyo; Hwang, Seong Sik; Lee, Deok Hyun; Hur, Do Haeng; Kim, Kyung Mo

    1997-09-01

    A multifrequency ACPD system was assembled which can measure very small crack. Stress corrosion cracking test system with SSRT operating high temperature was installed. Stress corrosion cracking test of newly developed alloy 600 and existing alloy 600 was carried out in steam atmosphere of 400 deg C. No crack was observed in both materials within a test period of 2,000 hrs. Corrosion fatigue test system operating at high temperature was installed in which fatigue crack was measured by CDPD. Lead enhanced the SCC of the Alloy 600 in high temperature water, had a tendency to modify a cracking morphology from intergranular to transgranular. Pit initiation preferentially occurred at Ti-rich carbide. Resistance to pit initiation decreased with increasing temperature up to 300 deg C. Test loop for erosion corrosion was designed and fabricated. Thin layer activation technique was very effective in measuring erosion corrosion. Erosion corrosion of a part of secondary side pipe was evaluated by the Check Family Codes of EPRI. Calculated values of pipe thickness by Check Family Codes coincided with the pipe thickness measured by UT with an error of {+-} 20%. Literature review on turbine failure showed that failure usually occurred in low pressure turbine rotor disc and causes of failure are stress corrosion cracking and corrosion fatigue. (author). 12 refs., 20 tabs., 77 figs.

  3. 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.)

  4. Virtualisation of casting engineering

    Directory of Open Access Journals (Sweden)

    J.S. Suchy

    2007-09-01

    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

  5. Improved corrosion resistance of a high-strength Mg–Al–Mn–Ca magnesium alloy made by rapid solidification powder metallurgy

    International Nuclear Information System (INIS)

    Highlights: ? Corrosion behavior of an Mg–Al–Mn–Ca alloy produced by SWAP was investigated. ? The SWAPed Mg alloy has superior mechanical property and high corrosion resistance. ? The high corrosion resistance is partly attributed to the dispersed intermetallic particles. ? Dispersion of intermetallic phase is favorable to the improvement of corrosion resistance. - Abstract: The mechanical property and in particular the corrosion behavior of an Mg–Al–Mn–Ca alloy produced by spinning water atomization process (SWAP) were investigated and compared to those of the alloys made by gravity cast and hot extrusion. It is found that the SWAPed alloy has not only superior mechanical properties but also distinguished corrosion resistance. The corrosion resistance of the SWAPed alloy is about 2.5 and 10 times higher than that of the hot-extruded and as-cast alloys, respectively, when immersed in 0.1 M NaCl solution. Potentiodynamic polarization shows that both the anodic and cathodic current densities of the three alloys in 0.1 M NaCl solution are in the order of SWAPed alloy < hot-extruded alloy < as-cast alloy. The depressed cathodic and anodic reactions of the SWAPed alloy are attributed to the fine dispersed intermetallic phase and the supersaturated composition in ?-Mg matrix, respectively. The present results demonstrate that the corrosion resistance of magnesium alloys can be greatly improved via the dispersion of intermetallic phase by the process sucse by the process such as SWAP.

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

    OpenAIRE

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

    2012-01-01

    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...

  7. Corrosion fatigue of steels

    International Nuclear Information System (INIS)

    Corrosion fatigue phenomena can be classified into two main groups according to the electrochemical state of the metal surface in the presence of electrolytes: the active and the passive state with an important sub-group of corrosion fatigue in the unstable passive state. The allowable stress for structures exposed to the conjoint action of corrosion and fatigue is influenced by many factors: kind of media, number of cycles, frequency, mean stress, size, notches, loading mode, alloy composition and mechanical strength. A critical literature review shows contradictory results if a classification by the electrochemical surface state is not applied. Case histories and counter measures illustrate the practical importance of corrosion fatigue in many branches of industry as well as the urgent need for a better knowledge about the mutual influence of the phenomena to get rules by which the engineer can appraise the risk of corrosion fatigue. (orig.)

  8. Nanomechanics of vascular endothelium.

    Science.gov (United States)

    Fels, Johannes; Jeggle, Pia; Liashkovich, Ivan; Peters, Wladimir; Oberleithner, Hans

    2014-03-01

    The mechanical characteristics of endothelial cells reveal four distinct compartments, namely glycocalyx, cell cortex, cytoplasm and nucleus. There is accumulating evidence that endothelial nanomechanics of these individual compartments control vascular physiology. Depending on protein composition, filament formation and interaction with cross-linker proteins, these four compartments determine endothelial stiffness. Structural organization and mechanical properties directly influence physiological processes such as endothelial barrier function, nitric oxide release and gene expression. This review will focus on endothelial nanomechanics and its impact on vascular function. PMID:24643677

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

    Directory of Open Access Journals (Sweden)

    Yanling Ni

    2014-07-01

    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.

  10. Inflammatory Cytokines in Vascular Dysfunction and Vascular Disease

    OpenAIRE

    Sprague, Alexander H.; Khalil, Raouf A.

    2009-01-01

    The vascular inflammatory response involves complex interaction between inflammatory cells (neutrophils, lymphocytes, monocytes, macrophages), endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and extracellular matrix (ECM). Vascular injury is associated with increased expression of adhesion molecules by ECs and recruitment of inflammatory cells, growth factors, and cytokines, with consequent effects on ECs, VSMCs and ECM. Cytokines include tumor necrosis factors, interleukins, l...

  11. Fillability of Thin-Wall Steel Castings

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-07-30

    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.

  12. Monitoring corrosion rates and localised corrosion in low conductivity water

    OpenAIRE

    Hilbert, Lisbeth Rischel

    2007-01-01

    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...

  13. Corrosion Failures in Marine Environment

    Directory of Open Access Journals (Sweden)

    R. Krishnan

    1985-04-01

    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, bimetallic corrosion, dealloying, cavitation and stress corrosion cracking are illustrated as typical examples of corrosion failures.

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

    Directory of Open Access Journals (Sweden)

    A. Kie?bus

    2007-01-01

    Full Text Available 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/approach: Die casting was carried out on 280 tone locking force hot-chamber die castingmachine. For the microstructure observation, a Olympus GX+70 metallographic microscope and a HITACHIS-3400N scanning electron microscope with a Thermo Noran EDS spectrometer equipped with SYSTEM SIXwere used.Findings: Based on the investigation carried out it was found that the AE44 magnesium alloy before diecasting is characterized by ?-Mg solid solution with globular, lamellar and acicular precipitations of Al11RE3and Al3RE phases. Moreover, there was found globular Mn-rich phase existence (probably Al8CeMn4 phase.After hot-chamber die casting the microstructure of AE44 alloys consist of equiaxed dendrites of ?-Mg withprecipitates of Al11RE3 and probably Al2RE phase.Research limitations/implications: Future researches should contain investigations of the influence of the hotchamber die casting process parameters on the microstructure and mechanical properties of AE44 magnesiumalloy.Practical implications: AE44 magnesium alloy can be cast with cold- and hot-chamber die casting machine.Results of investigation may be useful for preparing die casting technology of this alloy.Originality/value: The results of the researches make up a basis for the investigations of new magnesium alloyscontaining rare earth elements for hot chamber die casting designed to service in elevated temperature.

  15. Titan Casts Revealing Shadow

    Science.gov (United States)

    2004-05-01

    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,

  16. Nanomechanics of vascular endothelium

    OpenAIRE

    Fels, Johannes; Jeggle, Pia; Liashkovich, Ivan; Peters, Wladimir; Oberleithner, Hans

    2014-01-01

    The mechanical characteristics of endothelial cells reveal four distinct compartments, namely glycocalyx, cell cortex, cytoplasm and nucleus. There is accumulating evidence that endothelial nanomechanics of these individual compartments control vascular physiology. Depending on protein composition, filament formation and interaction with cross-linker proteins, these four compartments determine endothelial stiffness. Structural organization and mechanical properties directly influence physiolo...

  17. Corrosion behaviour of container materials for the disposal of high-level waste forms in rock salt formations

    International Nuclear Information System (INIS)

    Extensive laboratory-scale experiments to evaluate the long-term corrosion behaviour of selected materials in brines and first in situ experiments were performed. In the laboratory experiments the materials Ti 99.8-Pd, Hastelloy C4 and hot-rolled low carbon steel as well cast steel, spheroidal cast iron, Si-cast iron and the Ni-Resists type D2 and D4 were investigated. The investigated parameters were: temperature, gamma-radiation and different compositions of salt brines. (orig./PW)

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

    Directory of Open Access Journals (Sweden)

    Z. Stradomski

    2012-04-01

    Full Text Available 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 particles produce high erosive and corrosive wear. The work proposes an application of the ? phase as a component of precipitation strengthening mechanism in order to increase the functional properties of the material. Morphology and quantities of ? phase precipitates were determined, as well as its influence on the erosion and corrosion wear resistance. It was shown that annealing at 800°C or 900°C significantly improves tribological properties as compared with the supersaturated state, and the best erosion and corrosion wear resistance achieved due to the ferrite decomposition ? ? ?’ + ? was exhibited in the case of annealing at the temperature of 800°C for 3 hours.

  19. Evaluation of the Characteristics of the Aluminum Alloy Casting Material by Heat Treatment

    International Nuclear Information System (INIS)

    Aluminum is on active metal, but it is well known that its oxide film plays a role as protective barrier which is comparatively stable in air and neutral aqueous solution. Thus, aluminum alloys have been widely applied in architectural trim, cold and hot-water storage vessels and piping etc., furthermore, the aluminum alloy of AC8A have been widely used in mold casting material of engine piston because of its properties of temperature and wear resistance. In recent years, the oil price is getting higher and higher, thus the using of low quality oil has been significantly increased in engines of ship and vehicle. Therefore it is considered that evaluation of corrosion resistance as well as wear resistance of AC8A material is also important to improve its property and prolong its lifetime. In this study, the effect of solution and tempering heat treatment to corrosion and wear resistance is investigated with electrochemical method and measurement of hardness. The hardness decreased with solution heat treatment compared to mold casting condition, but its value increased with tempering heat treatment and exhibited the highest value of hardness with tempering heat treatment temperature at 190 .deg. C for 24hrs. Furthermore, corrosion resistance increased with decreasing of the hardness, and decreased with increasing of the hardness reversely. As a result, it is suggested that the optimum heat treatment to improve both corrosion and wear resistance is tempering heat treatment temperature at 190 .deg. C for 16hrs

  20. Genetic Pathways of Vascular Calcification

    OpenAIRE

    Bowman, Marion A. Hofmann; McNally, Elizabeth M.

    2012-01-01

    Vascular calcification is an independent risk factor for cardiovascular disease. Arterial calcification of the aorta, coronary, carotid and peripheral arteries becomes more prevalent with age. Genomewide association studies have identified regions of the genome linked to vascular calcification, and these same regions are linked to myocardial infarction risk. The 9p21 region linked to vascular disease and inflammation also associates with vascular calcification. In addition to these common var...

  1. Renal posttransplant's vascular complications

    Directory of Open Access Journals (Sweden)

    Baši? Dragoslav

    2003-01-01

    Full Text Available INTRODUCTION Despite high graft and recipient survival figures worldwide today, a variety of technical complications can threaten the transplant in the postoperative period. Vascular complications are commonly related to technical problems in establishing vascular continuity or to damage that occurs during donor nephrectomy or preservation [13]. AIM The aim of the presenting study is to evaluate counts and rates of vascular complications after renal transplantation and to compare the outcome by donor type. MATERIAL AND METHODS A total of 463 kidneys (319 from living related donor LD and 144 from cadaveric donor - CD were transplanted during the period between June 1975 and December 1998 at the Urology & Nephrology Institute of Clinical Centre of Serbia in Belgrade. Average recipients' age was 33.7 years (15-54 in LD group and 39.8 (19-62 in CD group. Retrospectively, we analyzed medical records of all recipients. Statistical analysis is estimated using Hi-squared test and Fischer's test of exact probability. RESULTS Major vascular complications including vascular anastomosis thrombosis, internal iliac artery stenosis, internal iliac artery rupture obliterant vasculitis and external iliac vein rupture were analyzed. In 25 recipients (5.4% some of major vascular complications were detected. Among these cases, 22 of them were from CD group vs. three from LD group. Relative rate of these complications was higher in CD group vs. LD group (p<0.0001. Among these complications dominant one was vascular anastomosis thrombosis which occurred in 18 recipients (17 from CD vs. one from LD. Of these recipients 16 from CD lost the graft, while the rest of two (one from each group had lethal outcome. DISCUSSION Thrombosis of renal allograft vascular anastomosis site is the most severe complication following renal transplantation. In the literature, renal allograft thrombosis is reported with different incidence rates, from 0.5-4% [14, 15, 16]. Data from the present study demonstrate that the rate of this complication in LD group was low, only 0.3%, but significantly higher in CD group - 11.8%. Many factors should be considered in order to understand for such significant difference among these groups. First of all, cadaveric transplant activity in our country is very low. In our series, median waiting period for renal transplantation was 2.8 years in LD group vs. 4.8 years in CD group (p<0.01. Also, vascular damages because of long term hemodialysis are contributing factors. Mean age of CD recipients was 7.4 years bigger vs. LD recipients. Primary cadaveric graft damage by accident and further manipulations during cadaveric donor nephrectomy, preservation and per-fusion are additional factors compromising the quality of cadaveric renal transplant outcome. Also, preoperative evaluation of cadaveric grafts is not as exact as in cases of LD grafts (excretory urography arteriography, etc. In the available transplant literature it is almost impossible to find data about vascular complications by different donor types. Mostly, authors offer experiences related to all transplants and most of them agree that in the present time better results are obtained using living donors [17].

  2. Vascular alterations in schwannoma.

    Science.gov (United States)

    Papiez, Joseph; Rojiani, Mumtaz V; Rojiani, Amyn M

    2014-01-01

    Schwannomas or neurilemmoma are benign peripheral nerve sheath tumors, which most frequently occur at the cerebellopontine angle. This morphologic study examines vascular alterations in these tumors, comparing them to other benign spindle cell neoplasms of the nervous system, while correlating these findings with evidence of vascular permeability. Thirty-four nervous system spindle cell neoplasms, sixteen schwannomas, nine fibroblastic/transitional meningiomas and nine peripheral neurofibromas were stained with H&E, Prussian-blue stain, and immunoreacted for factor VIII-related antigen and interstitial albumin. Schwannomas had focal clusters of vascular proliferation including groups of small thin-walled vessels, as well as larger vessels with extensive hyalinization. Neurofibromas and meningiomas almost uniformly had modest numbers of well-defined, thin walled individual vessels. Free hemosiderin and hemosiderin-laden macrophages were frequently identified in schwannomas. Prussian-blue stain for iron revealed focal or fairly widespread positivity in almost all schwannomas, only one meningioma and none of the neurofibromas. Immunoreaction for albumin demonstrated leakage of vascular proteins into the interstitium confirming tumor vessel permeability in schwannomas. Neither neurofibromas nor meningiomas displayed any detectable interstitial albumin. The above findings confirm a degree of reactive proliferation of vessels in schwannoma along with functional deficits in their vascular integrity with permeability to protein and blood. The presence of hyalinized vessels, hemosiderin, both free and within macrophages, and more readily evident Prussian blue staining, may provide an additional diagnostic clue in discriminating between histologically similar spindle cell lesions. The study however raises the possibility that these changes likely precede or facilitate the degenerative 'ancient change' seen in some schwannoma. PMID:25120781

  3. Microstructure quantitative analysis of aluminum skeleton castings

    Directory of Open Access Journals (Sweden)

    M. Cholewa

    2008-12-01

    Full Text Available In this article authors showed method for manufacturing of closed skeleton castings with hypo – eutectic and eutectic aluminiumalloys. Experimental castings were manufactured in variables technological conditions: range of pouring temperature 680 ÷ 740 °C,temperature of mould 20 ÷ 100 °C and height of gating system above casting level 105 ÷ 175 mm. Structural analysis of studied skeletoncastings was conducted. Degree of refinement of structure in typical region of skeleton casting was compared. Qualitative and quantitativedifferent degree of fineness of eutectic silicon was confirmed. Casting in established technological conditions enables manufacturedskeletons which repeatable geometry, suitable external geometrical form of casting and required quality.

  4. The vascular secret of Klotho

    DEFF Research Database (Denmark)

    Lewin, Ewa; Olgaard, Klaus

    2015-01-01

    Klotho is an evolutionarily highly conserved protein related to longevity. Increasing evidence of a vascular protecting effect of the Klotho protein has emerged and might be important for future treatments of uremic vascular calcification. It is still disputed whether Klotho is locally expressed in the vasculature or whether its vascular effects arise uniquely from its presence in the circulation.

  5. The vascular secret of Klotho.

    Science.gov (United States)

    Lewin, Ewa; Olgaard, Klaus

    2015-06-01

    Klotho is an evolutionarily highly conserved protein related to longevity. Increasing evidence of a vascular protecting effect of the Klotho protein has emerged and might be important for future treatments of uremic vascular calcification. It is still disputed whether Klotho is locally expressed in the vasculature or whether its vascular effects arise uniquely from its presence in the circulation. PMID:26024025

  6. Flow impact on cast ingots

    Science.gov (United States)

    Ratke, Lorenz; Fautrelle, Yves; Lacaze, Jacques; Müller, Georg; Roosz, Andras; Zimmermann, Gerhard; Jarry, Phillippe; Kieft, Rene; Csepeli, Zsolt; Sándor, Józef; Grün, Gerd-Ulrich; Sillinger, Nándor; Gerke-Cantow, Ralf

    2005-10-01

    Aluminium alloys are a standard cast metal used in a number of automotive and transportation applications, allowing manufacturers to reduce vehicle weight, increase the strength of components and improve emission controls. One of the most challenging problems associated with aluminium casting is the influence of convection during all stages of solidification. The strength of fluid flow changes the as-cast internal structure (microstructure) such that the yield, fracture and fatigue strengths of the cast ingot can vary considerably. Although the importance of fluid flow has been recognised for decades, not even a simple model has been developed to predict the effect on microstructure. The MICAST project aims to identify and control experimentally the fluid-flow patterns that affect microstructure evolution during casting processes, and to develop analytical and advanced numerical models. The microgravity environment of the International Space Station and sounding rockets is of special importance to this project because only there are all gravity-induced convections eliminated and well-defined conditions for solidification prevail that can be disturbed by fluid flow controlled by experimenters.

  7. Casting Castings: A Classroom Hands-on Activity

    Science.gov (United States)

    Johnson, Craig

    This learning activity will provide a useful technique for students to learn casting concepts. The class will be allowed a hands-on experience with casting. Students will make their own fishing sinkers. The lesson plan document includes step by step instructions for the lesson along with photographs.This activity would be appropriate for high school and college level students. The lesson should take about one hour of class time. This document will serve as a framework for instructors and may be downloaded in PDF format.

  8. Hot corrosion behavior of low pressure plasma sprayed NiCoCrAlY+Ta coatings on nickel base superalloys

    International Nuclear Information System (INIS)

    The hot corrosion behavior of NiCoCrAlY+Ta coatings obtained by low-pressure plasma spraying has been investigated (type I hot corrosion with T = 8500C). These coatings have been deposited on two nickel-base superalloys and on a cast alloy of the same composition as the coating. Comparison of the cyclic oxidation behavior at 8500C between the sprayed coating and the cast alloy shows that the sprayed material exhibits a satisfactory and higher resistance than the cast alloy. In the latter case, repeated spalling of the oxide scale results from fractures often associated with Y-rich oxide protrusions. Hot corrosion experiments (salt-spraying test with T = 8500C and thermal cycling in air every hour) have been conducted on two cast alloys, NiCoCrAl+Ta and NiCoCrAlY+Ta. The Y-containing alloy has a better corrosion resistance than the other alloy which is subject to extensive oxide spallation. In both cases, morphologies typical of basic fluxing processes, involving Cr, Al, Y, and Ta can be observed in highly attacked zones. Finally, tests on plasma sprayed coatings show a high resistance to hot corrosion of these coatings, regardless of the substrate used: a fine adherent alumina layer is formed, and only a limited fluxing of Cr, Al, and Y takes place. The quite different results obtained on cast and sprayed alloys imply that data relative to cast alloys can be unreliable when one wants to predict high temperature behavior and especially high temperature behavior and especially lifetimes of overlay coatings

  9. Intercrystalline corrosion fatigue in steel

    International Nuclear Information System (INIS)

    The importance of transcrystalline and intercrystalline fatigue cracking in failure analysis is shown. Characteristic differences between intercrystalline corrosion fatigue and intercrystalline stress corrosion cracking are pointed out. Time-dependent stress corrosion crack growth under sustained loads gives rise to strongly frequency-dependent corrosion fatigue crack growth under cyclic loads. Intercrystalline 'true' corrosion fatigue depends on the cyclic stress intensity range and on the environment. Intergranular cracks can definitely be due to fatigue. (orig.)

  10. Irritants and corrosives.

    Science.gov (United States)

    Tovar, Richard; Leikin, Jerrold B

    2015-02-01

    This article reviews toxic chemicals that cause irritation and damage to single and multiple organ systems (corrosion) in an acute fashion. An irritant toxic chemical causes reversible damage to skin or other organ system, whereas a corrosive agent produces irreversible damage, namely, visible necrosis into integumentary layers, following application of a substance for up to 4 hours. Corrosive reactions can cause coagulation or liquefaction necrosis. Damaged areas are typified by ulcers, bleeding, bloody scabs, and eventual discoloration caused by blanching of the skin, complete areas of alopecia, and scars. Histopathology should be considered to evaluate questionable lesions. PMID:25455665

  11. Panel report on corrosion in energy systems

    International Nuclear Information System (INIS)

    Corrosion problems in high-temperature (non aqueous) energy systems, corrosion in aqueous energy systems and institutional problems inhibiting the development of corrosion science and engineering are discussed

  12. Susceptibility of copper to general and pitting corrosion in saline groundwater

    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, which is responsible for the corrosion protection. In this work the susceptibility of Cu OFP to general and pitting corrosion was investigated in saline (1.45% Cl-) groundwater at T = 80 deg C and p = 14 MPa using electrochemical techniques and weight loss measurements in autoclave conditions. The results were compared with earlier results gained in similar conditions but in highly saline (5.4% Cl-) groundwater. The conclusions presented here are strictly applicable only for the present case, where the groundwater was deoxygenated with nitrogen bubbling (ensuring dissolved oxygen level of lower than 5 mg/l) and where there was almost no mass transfer limitation for the corrosion products away from the surface. The main observations made are: The corrosion potential of Cu OFP in all test runs was in the range of -0.10 VSHE corr SHE, i.e. about 0.1 V higher than in the highly saline groundwater; At the corrosion potential active dissolution (corrosion) of Cu OFP takes place, as was the case in highly saline groundwater. However, the corrosion rate based on weight loss measurements of corrosion coupons was 0.014 mm/y, about 30% lower than in the highly saline groundwater. (orig.)

  13. Susceptibility of copper to general and pitting corrosion in saline groundwater

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-02-01

    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, which is responsible for the corrosion protection. In this work the susceptibility of Cu OFP to general and pitting corrosion was investigated in saline (1.45% Cl{sup -}) groundwater at T = 80 deg C and p = 14 MPa using electrochemical techniques and weight loss measurements in autoclave conditions. The results were compared with earlier results gained in similar conditions but in highly saline (5.4% Cl{sup -}) groundwater. The conclusions presented here are strictly applicable only for the present case, where the groundwater was deoxygenated with nitrogen bubbling (ensuring dissolved oxygen level of lower than 5 mg/l) and where there was almost no mass transfer limitation for the corrosion products away from the surface. The main observations made are: The corrosion potential of Cu OFP in all test runs was in the range of -0.10 V{sub SHE} < E{sub corr} < 0.05 V{sub SHE}, i.e. about 0.1 V higher than in the highly saline groundwater; At the corrosion potential active dissolution (corrosion) of Cu OFP takes place, as was the case in highly saline groundwater. However, the corrosion rate based on weight loss measurements of corrosion coupons was 0.014 mm/y, about 30% lower than in the highly saline groundwater. (orig.)

  14. A study on the mechanical and corrosion properties of lead added magnesium alloys

    International Nuclear Information System (INIS)

    Highlights: ? Mg is the lightest metal used in structural applications. ? The most important disadvantages of Mg alloys are their low strength and corrosion resistance. ? Different ratios of Pb were added to alloys reinforced with Mg2Si particles. ? According to corrosion tests, corrosion resistance increased with the addition of Pb. -- Abstract: The purpose of this study was to investigate the effect adding Pb at different ratios had on the corrosion properties of Mg alloys. Pb, at a rate of 0.2%, 0.5%, and 1%, was added to Mg-10% Al–12Si. The microstructure characterisation, mechanical and corrosion properties of alloys, produced using a casting method was investigated. Light Optical Microscopy (LOM), X-Ray Diffraction (XRD) analyses and a Scanning Electron Microscope (SEM) were used to conduct the microstructure characterisation of investigated alloys. Corrosion tests were performed by suspending the samples of certain sizes into the 3.5% NaCl solutions measuring the weight loss, and also by potentiodynamic polarisation measurements in the same solution. According to corrosion experiment results, Ikor decreased with the addition of Pb, causing an increase in the corrosion resistance.

  15. Centrifugal slip casting of components

    International Nuclear Information System (INIS)

    Research in layered and functionally gradient materials has emerged because of the increasing demand for high-performance engineering materials. Many techniques have been used to produce layered and functionally gradient components. Common examples include thermal spray processing, powder processing, chemical and physical vapor deposition, high-temperature or combustion synthesis, diffusion treatments, microwave processing and infiltration. Of these techniques, powder processing routes offer excellent microstructural control and product quality, and they are capable of producing large components. Centrifugal slip casting is a powder-processing technique combining the effects of slip casting and centrifugation. In slip casting, consolidation takes place as fluid is removed by the porous mold. Particles within the slip move with the suspending fluid until reaching the mold wall, at which point they are consolidated. In centrifugation, particles within the slip move through the fluid at a rate dependent upon the gravitational force and particle drag

  16. BWR steel containment corrosion

    International Nuclear Information System (INIS)

    The report describes regulatory actions taken after corrosion was discovered in the drywell at the Oyster Creek Plant and in the torus at the Nine Mile Point 1 Plant. The report describes the causes of corrosion, requirements for monitoring corrosion, and measures to mitigate the corrosive environment for the two plants. The report describes the issuances of generic letters and information notices either to collect information to determine whether the problem is generic or to alert the licensees of similar plants about the existence of such a problem. Implementation of measures to enhance the containment performance under severe accident conditions is discussed. A study by Brookhaven National Laboratory (BNL) of the performance of a degraded containment under severe accident conditions is summarized. The details of the BNL study are in the appendix to the report

  17. Electrochemical noise in corrosion

    International Nuclear Information System (INIS)

    By varying different variables (potential, chloride content, surface pretreatment etc.) it is possible to show the effect of increasingly harsher corrosion conditions on passive-layer stability. These changes will not be detected by conventional methods e.g. measurement of passive current density, until a very late stage. Electrochemical noise measurement will allow the action of inhibitors to be detected in a rapid and effective manner. High-alloy steels and titanium claddings subjected to pitting corrosion in chloride-containing media demonstrate how to use this method for problem solutions and to open up new practical applications. The effect of mechanical stresses (natural, tensile) on the corrosion system can be detected by electrochemical noise which opens up new methods for crack corrosion studying and monitoring. (orig./DG)

  18. Casting propellant in rocket engine

    Science.gov (United States)

    Roach, J. E.; Froehling, S. C. (inventors)

    1976-01-01

    A method is described for casting a solid propellant in the casing of a rocket engine having a continuous wall with a single opening which is formed by leaves of a material which melt at a temperature of the propellant and with curved edges concentric to the curvature of the spherical casing. The leaves are inserted into the spherical casing through the opening forming a core having a greater width than the width of the single opening and with curved peripheral edges. The cast propellant forms a solid mass and then heated to melt the leaves and provide a central opening with radial projecting flutes.

  19. Caste System And Caste Practices In Tamil Country

    OpenAIRE

    Gnanavel, T.; Selvamuthu Kumarasami, L.

    2012-01-01

    Social life with its religious practices, caste traditions and conventional distinctions continued without any remarkable change throughout the Vijayanagar Rule. Linguistic traditions, pride, prejudice and geographical barriers led to decentralization and there was a struggle for supremacy. The Tamil Society managed to retain many of its traditional cultural traits fairly intact. Its communal ramification and the inter communal dissensions not infrequently descending to the...

  20. Casting behavior of titanium alloys in a centrifugal casting machine.

    Science.gov (United States)

    Watanabe, K; Miyakawa, O; Takada, Y; Okuno, O; Okabe, T

    2003-05-01

    Since dental casting requires replication of complex shapes with great accuracy, this study examined how well some commercial titanium alloys and experimental titanium-copper alloys filled a mold cavity. The metals examined were three types of commercial dental titanium [commercially pure titanium (hereinafter noted as CP-Ti), Ti-6Al-4V (T64) and Ti-6Al-7Nb (T67)], and experimental titanium-copper alloys [3%, 5% and 10% Cu (mass %)]. The volume percentage filling the cavity was evaluated in castings prepared in a very thin perforated sheet pattern and cast in a centrifugal casting machine. The flow behavior of the molten metal was also examined using a so-called "tracer element technique." The amounts of CP-Ti and all the Ti-Cu alloys filling the cavity were similar; less T64 and T67 filled the cavity. However, the Ti-Cu alloys failed to reach the end of the cavities due to a lower fluidity compared to the other metals. A mold prepared with specially designed perforated sheets was effective at differentiating the flow behavior of the metals tested. The present technique also revealed that the more viscous Ti-Cu alloys with a wide freezing range failed to sequentially flow to the end of the cavity. PMID:12593955

  1. Effect of radiation on anaerobic corrosion of iron

    International Nuclear Information System (INIS)

    To ensure the safe encapsulation of spent nuclear fuel elements for geological disposal, SKB of Sweden are considering using the Advanced Cold Process Canister, which consists of an outer copper canister and a cast iron insert. A programme of work has been carried out to investigate a range of corrosion issues associated with the canister, including measurements of gas generation due to the anaerobic corrosion of ferrous materials (carbon steel and cast iron) over a range of conditions. To date, all this work has been conducted in the absence of a radiation field. SKB asked Serco Assurance to carry out a set of experiments designed to investigate the effect of radiation on the corrosion of steel in repository environments. This report describes the experimental programme and presents the results that were obtained. The measurements were carried out in the type of gas cell used previously, in which the change in gas pressure was measured using a liquid-filled manometer. The test cells were placed in a radiation cell and positioned so that the received radiation dose was equivalent to that expected in the repository. Control cells were used to allow for any gas generation caused by radiolytic breakdown of the construction materials and the water. Tests were carried out at two temperatures (30 deg C and 50 deg C), two dose rates (11 Gray/hr and 300 Gray/hr), and in two different artificial groundwaters. A total of four tests were carried out, using carbon steel wires as the test material. The cells were exposed for a period of several months, after which they were dismantled and the corrosion product on one wire from each test cell was analysed using Raman spectroscopy. The report presents the results from the gas generation tests and compares the results obtained under irradiated conditions to results obtained previously in the absence of radiation. Radiation was found to enhance the corrosion rate at both dose rates but the greatest enhancement occurred at the higher dose rate. The corrosion products were predominantly magnetite, with some indications of unidentified higher oxidation state corrosion products being formed at the higher dose rates. The main conclusions from the work are as follows: 1. The presence of gamma radiation fields increases the anaerobic corrosion rate of carbon steel in artificial groundwaters simulating those expected in the SKB repository. At 11 Gray/hr the increase only lasts for approximately 7,000 hours, but at 300 Gray/hr the enhancement is longer lasting and may be continuous. 2. The enhancement in the corrosion rate is greater in Allard water, where a 30 fold increase in corrosion rate was observed, than in bentonite-equilibrated groundwater, which had a higher ionic strength and a higher initial pH, where the radiation-induced enhancement was 10-20 times. 3. The predominant corrosion product of anaerobic corrosion of iron under irradiated conditions is magnetite, but there was some evidence of higher oxidation state oxyhydroxides under the high dose rate conditions. 4. A more detailed analysis of the radiochemical conditions in the tests is required to develop a more detailed understanding of the reasons for the increase in corrosion rate when irradiated

  2. Effect of radiation on anaerobic corrosion of iron

    Energy Technology Data Exchange (ETDEWEB)

    Smart, N.R.; Rance, A.P. [Serco Assurance, Risley (United Kingdom)

    2005-01-01

    To ensure the safe encapsulation of spent nuclear fuel elements for geological disposal, SKB of Sweden are considering using the Advanced Cold Process Canister, which consists of an outer copper canister and a cast iron insert. A programme of work has been carried out to investigate a range of corrosion issues associated with the canister, including measurements of gas generation due to the anaerobic corrosion of ferrous materials (carbon steel and cast iron) over a range of conditions. To date, all this work has been conducted in the absence of a radiation field. SKB asked Serco Assurance to carry out a set of experiments designed to investigate the effect of radiation on the corrosion of steel in repository environments. This report describes the experimental programme and presents the results that were obtained. The measurements were carried out in the type of gas cell used previously, in which the change in gas pressure was measured using a liquid-filled manometer. The test cells were placed in a radiation cell and positioned so that the received radiation dose was equivalent to that expected in the repository. Control cells were used to allow for any gas generation caused by radiolytic breakdown of the construction materials and the water. Tests were carried out at two temperatures (30 deg C and 50 deg C), two dose rates (11 Gray/hr and 300 Gray/hr), and in two different artificial groundwaters. A total of four tests were carried out, using carbon steel wires as the test material. The cells were exposed for a period of several months, after which they were dismantled and the corrosion product on one wire from each test cell was analysed using Raman spectroscopy. The report presents the results from the gas generation tests and compares the results obtained under irradiated conditions to results obtained previously in the absence of radiation. Radiation was found to enhance the corrosion rate at both dose rates but the greatest enhancement occurred at the higher dose rate. The corrosion products were predominantly magnetite, with some indications of unidentified higher oxidation state corrosion products being formed at the higher dose rates. The main conclusions from the work are as follows: 1. The presence of gamma radiation fields increases the anaerobic corrosion rate of carbon steel in artificial groundwaters simulating those expected in the SKB repository. At 11 Gray/hr the increase only lasts for approximately 7,000 hours, but at 300 Gray/hr the enhancement is longer lasting and may be continuous. 2. The enhancement in the corrosion rate is greater in Allard water, where a 30 fold increase in corrosion rate was observed, than in bentonite-equilibrated groundwater, which had a higher ionic strength and a higher initial pH, where the radiation-induced enhancement was 10-20 times. 3. The predominant corrosion product of anaerobic corrosion of iron under irradiated conditions is magnetite, but there was some evidence of higher oxidation state oxyhydroxides under the high dose rate conditions. 4. A more detailed analysis of the radiochemical conditions in the tests is required to develop a more detailed understanding of the reasons for the increase in corrosion rate when irradiated.

  3. Corrosion Resistance of Co-Cr-Mo Alloy Used in Dentistry

    Directory of Open Access Journals (Sweden)

    ?ukaszczyk A.

    2015-04-01

    Full Text Available The presented paper studies the effect of the casting technology on the corrosion resistance of Co-Cr-Mo alloy. The investigations were conducted on a commercial alloy with the brand name ARGELOY N.P SPECIAL (Co-Cr-Mo produced by Argen as well as the same alloy melted and cast by the lost wax casting method performed by a dental technician. The corrosion behavior of the dental alloys in an artificial saliva was studied with the use of the following electrochemical techniques: open circuit potential and voltammetry. After the electrochemical tests, studies of the surface of the examined alloys were performed by means of a scanning electron microscope with an X-ray microanalyzer. The results of the electrochemical studies show that the dependence of the corrosion resistance on the microstructure associated with the recasting process is marginal. The results of the electrochemical studies of the considered alloy clearly point to their good corrosion resistance in the discussed environment.

  4. Plant Vascular Biology 2010

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Biao

    2014-11-17

    This grant supported the Second International Conference on Plant Vascular Biology (PVB 2010) held July 24-28, 2010 on the campus of Ohio State University, Columbus, Ohio. Biao Ding (Ohio State University; OSU) and David Hannapel (Iowa State University; ISU) served as co-chairs of this conference. Biao Ding served as the local organizer. PVB is defined broadly here to include studies on the biogenesis, structure and function of transport systems in plants, under conditions of normal plant growth and development as well as of plant interactions with pathogens. The transport systems cover broadly the xylem, phloem, plasmodesmata and vascular cell membranes. The PVB concept has emerged in recent years to emphasize the integrative nature of the transport systems and approaches to investigate them.

  5. Vascular cognitive impairment

    Directory of Open Access Journals (Sweden)

    N.V. Vakhnina

    2014-05-01

    Full Text Available Vascular pathology of the brain is the second most common cause of cognitive impairment after Alzheimer's disease. The article describes the modern concepts of etiology, pathogenetic mechanisms, clinical features and approaches to diagnosis and therapy of vascular cognitive impairment (VCI. Cerebrovascular accident, chronic cerebral circulatory insufficiency and their combination, sometimes in combination with a concomitant neurodegenerative process, are shown to be the major types of brain lesions leading to VCI. The clinical presentation of VCI is characterized by the neuropsychological status dominated by impairment of the executive frontal functions (planning, control, attention in combination with focal neurological symptoms. The diagnosis is based on comparing of the revealed neuropsychological and neurological features with neuroimaging data. Neurometabolic, acetylcholinergic, glutamatergic, and other vasoactive drugs and non-pharmacological methods are widely used to treat VCI. 

  6. [Vascular variability syndromes].

    Science.gov (United States)

    Otsuka, Kuniaki; Okajima, Kiyotaka; Yamanaka, Takashi; Cornelissen, Germaine

    2014-08-01

    Analytical global and local methods applied to human blood pressure (BP) records of around-the-clock measurements. The chronobiological interpretation of ambulatory BP monitoring records in the light of time-specified reference values derived from healthy peers matched by sex and age identify vascular variability disorders (VVDs) for an assessment of cardio-, cerebro-, and renovascular disease risk. VVD includes circadian BP over-swinging (CHAT, short for circadian hyper-amplitude tension), deficient heart rate variability, MESOR (midline-estimating statistic of rhythm) hypertension, excessively elevated pulse pressure over 60 mmHg, BP ecphasia (an odd timing of the circadian rhythms in BP but not in that of heart rate) and frequency alteration. The term MESOR-hypertension indicates only one of several VVDs that can combine to for sets of 2, 3 and n-component vascular variability syndromes. PMID:25167758

  7. Corrosion of beryllium

    International Nuclear Information System (INIS)

    The corrosion behavior of beryllium in aqueous and elevated-temperature oxidizing environments has been extensively studied for early-intended use of beryllium in nuclear reactors and in jet and rocket propulsion systems. Since that time, beryllium has been used as a structural material in les corrosive environments. Its primary applications include gyro systems, mirror and reentry vehicle structures, and aircraft brakes. Only a small amount of information has been published that is directly related to the evaluation of beryllium for service in the less severe or normal atmospheric environments associated with these applications. Despite the lack of published data on the corrosion of beryllium in atmospheric environments, much can be deduced about its corrosion behavior from studies of aqueous corrosion and the experiences of fabricators and users in applying, handling, processing, storing, and shipping beryllium components. The methods of corrosion protection implemented to resist water and high-temperature gaseous environments provide useful information on methods that can be applied to protect beryllium for service in future long-term structural applications

  8. Monitoring Microbially Influenced Corrosion

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel

    2000-01-01

    Abstract Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria (SRB). The applicability and reliability of a number of corrosion monitoring techniques for monitoring MIC has been evaluated in experiments conducted in near neutral sterile hydrogen sulphide saline solutions (pH 6 to 8.5, 0-107 mg/l sulphide), SRB active artificial sea water and SRB active simulated marine sediment. Electrochemical techniques as LPR, EIS and potentiodynamic polarisations give distorted data dominated by capacitative and diffusional effects and unreliable corrosion rates, when biofilm and ferrous sulphide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 by electrochemical techniques. Weight loss coupons and ER are recommended as necessary basic monitoring techniques. EIS might be used for detection of MIC as the appearance of very large capacitances can be attributed to the combined ferrous sulphide and biofilm formation. Capacitance correlates directly with sulphide concentration in sterile sulphide media. Keywords: Corrosion monitoring, carbon steel, MIC, SRB, hydrogen sulphide, EIS

  9. Defining Vascular Stem Cells

    OpenAIRE

    Lin, Ching-Shwun; Lue, Tom F

    2013-01-01

    Mesenchymal stem cells (MSCs) exist in most adult tissues and have been located near or within blood vessels. Although “perivascular” has been commonly used to describe such locations, increasing evidence points at the vessel wall as the exact location. Thus, “vascular stem cells (VSCs)” is recommended as a more accurate term for MSCs. Furthermore, 2 cell populations, namely pericytes and adventitial progenitor cells (APCs), are the likely VSCs. The pericyte evidence relies on the so-called p...

  10. Vascular access today

    OpenAIRE

    Pantelias, Konstantinos; Grapsa, Eirini

    2012-01-01

    The number of patients with chronic kidney disease requiring renal replacement therapy has increased worldwide. The most common replacement therapy is hemodialysis (HD). Vascular access (VA) has a key role for successful treatment. Despite the advances that have taken place in the field of the HD procedure, few things have changed with regards to VA in recent years. Arteriovenous fistula (AVF), polytetrafluoroethylene graft and the cuffed double lumen silicone catheter are the most common use...

  11. Computer aided casting methoding of railway system

    OpenAIRE

    St. M. Dobosz; A. Chojecki; R. Skoczylas

    2008-01-01

    Authors prepared the casting technology for the frog. Casting method has been verified by simulation, using MAGMASOFT technique. In multistep simulation it was found that the positioning of casting in the mould feeding and some details of construction must be changed. Finally authors have presented the optimised solution of the technology which eliminates the porosity of casting. Analyses of the distribution of the stress during solidification and cooling in the mould proves that the deformat...

  12. Developing technological process of obtaining giality casts

    Directory of Open Access Journals (Sweden)

    A. Issagulov

    2014-10-01

    Full Text Available The article considers the process of manufacturing castings using sand-resin forms and alloying furnace. Were the optimal technological parameters of manufacturing shell molds for the manufacture of castings of heating equipment. Using the same upon receipt of castings by casting in shell molds furnace alloying and deoxidation of the metal will provide consumers with quality products and have a positive impact on the economy in general engineering.

  13. Behaviour of oxygen in cast irons

    OpenAIRE

    T. Elbel; J. Senberger; A. Zadera; Hampl, J

    2008-01-01

    Purpose: Cast irons are the basic structural material and they form 75% of the world production of castings. The crystallization of cast iron and the formation of graphite are a complex process influencing by oxygen. The aim of our study is to identify the role of oxygen in Fe-C-Si melts.Design/methodology/approach: Continuous comparison of changes in metal composition and oxygen activity during melting, pouring, and solidification of experimental castings, using metallographic methods and mi...

  14. Study of pinholes genesis in iron castings

    OpenAIRE

    T. Elbel; Hampl, J; M. Senkypl

    2011-01-01

    Purpose: The study concerns the formation of pinholes in castings formed by reaction between a green foundry mould and lamellargraphite cast iron. Great numbers of works have been aimed at clarifying the causes of pinholes formation in iron castings. In spite of thisthere exists no united opinion on the pinholes formation (genesis) and the authors of this contribution having studied this phenomenon incompacted graphite and spheroidal graphite iron castings were also aimed at lamellar graphite...

  15. Cast functional accessories for heat treatment furnaces

    OpenAIRE

    A. Drotlew; B. Piekarski

    2010-01-01

    The study gives examples of the cast functional accessories operating in furnaces for the heat treatment of metals and alloys. The describeddesign solutions of castings and their respective assemblies are used for charge preparation and handling. They were put in systematicorder depending on furnace design and the technological purpose of heat treatment. Basic grades of austenitic cast steel, used for castings of this type, were enumerated, and examples of general guidelines formulated for th...

  16. Significance of coplanar macrocells to corrosion in concrete-embedded steel

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, P. [Univ. Autonoma de Nuevo Leon (Mexico); Ramirez, E. [Inst. de Investigacion Tecnologica Industrial y de Normas Tecnicas, Lima (Peru); Feliu, S.; Gonzalez, J.A. [Centro Nacional de Investigaciones Metalurgicas, Madrid (Spain); Lopez, W. [CEMEX, S.A. Monterrey (Mexico)

    1999-03-01

    The influence of microcells and galvanic macrocells on the corrosion kinetics of concrete-embedded steel was investigated experimentally. Nine stainless steel/carbon steel coplanar macrocouples in cathodic-to-anodic ratios of 0.02 to 50 were cast in concrete slabs made from cement, sand, and water in a 1:3:0:5 proportion plus 2% calcium chloride (CaCl{sub 2}) per cement weight. Corrosion potential (E{sub corr}), galvanic current (i{sub g}), polarization resistance (R{sub p}), and impedance measurements from 100 kHz to 0.01 Hz were made for the two metals, coupled and uncoupled. i{sub g} data provided by a zero resistance ammeter led to potentially underestimated corrosion rates for anodic areas, whereas R{sub p} measurements provided fairly reliable corrosion rates. Macrocells polarized anodic areas very slightly at points where an anodic and a cathodic process took place simultaneously.

  17. Resistance to corrosion of magnesium alloy AZ31 after plastic working

    Directory of Open Access Journals (Sweden)

    J. Przondziono

    2011-10-01

    Full Text Available The study presents results of electrochemical and chemical corrosion resistance tests of magnesium alloy AZ31 after plastic working. Electrochemical measurements were carried out in 1,35 % solution of NaCl. On the ground of registered polarisation curves, typical features characterising resistance to electrochemical corrosion, were determined. Resistance to chemical corrosion was tested by means of immersion in 3,5%solution of NaCl for the period of 1_5 days. By means of scanning electron microscope with field emission FE SEM S-4 200 Hitachi, qualitative and quantitative analysis of chemical composition in microareas was made. Results of surface layer morphology tests were presented. In order to compare corrosion properties, analogical tests were carried out for the alloy AZ31 obtained by means of pressure die casting.

  18. Pulmonary vascular imaging

    International Nuclear Information System (INIS)

    A wide range of pulmonary vascular imaging techniques are available for the diagnostic evaluation of patients with suspected pulmonary vascular disease. The characteristics of any ideal technique would include high sensitivity and specificity, safety, simplicity, and sequential applicability. To date, no single technique meets these ideal characteristics. Conventional pulmonary angiography remains the gold standard for the diagnosis of acute thromboembolic disease despite the introduction of newer techniques such as digital subtraction angiography and magnetic resonance imaging. Improved noninvasive lower extremity venous testing methods, particularly impedance plethysmography, and ventilation-perfusion scanning can play significant roles in the noninvasive diagnosis of acute pulmonary emboli when properly applied. Ventilation-perfusion scanning may also be useful as a screening test to differentiate possible primary pulmonary hypertension from chronic thromboembolic pulmonary hypertension. And, finally, angioscopy may be a useful adjunctive technique to detect chronic thromboembolic disease and determine operability. Optimal clinical decision-making, however, will continue to require the proper interpretation of adjunctive information obtained from the less-invasive techniques, applied with an understanding of the natural history of the various forms of pulmonary vascular disease and with a knowledge of the capabilities and shortcomings of the individual techniqueshortcomings of the individual techniques

  19. Corrosion and passivation behavior of Mg-Zn-Y-Al alloys prepared by cooling rate-controlled solidification

    International Nuclear Information System (INIS)

    Highly corrosion-resistant nanocrystalline Mg-Zn-Y-Al multi-phase alloys have been prepared by consolidation of rapidly solidified (RS) ribbons. The relation between corrosion behavior and microstructure evolution of Mg-Zn-Y-Al alloys with a long period stacking ordered phase has been investigated. In order to clarify the influence of rapid solidification on the occurrence of localized corrosion such as filiform corrosion, several Mg96.75Zn0.75Y2Al0.5 (at.%) alloys with different cooling rates are fabricated by the gravity casting, copper mould injection casting and melt-spinning techniques and their corrosion behavior and microstructures are examined by the salt water immersion test, electrochemical measurements, GDOES, XRD, SEM and TEM. To clarify the effect of aluminium addition on the improvement in corrosion resistance of the alloys, several Mg97.25-xZn0.75Y2Alx alloys with different aluminium contents are fabricated by consolidating RS ribbons and the formation of corroded films on the Mg-Zn-Y-Al alloys have been investigated. Rapid solidification brings about the grain refinement and an increase in the solid solubility of zinc, yttrium and aluminium into the magnesium matrix, enhancing microstructural and electrochemical homogeneity, which in turn enhanced corrosion resistance. The addition of aluminium to magnesium can modify the structure and chemical composition of surfacructure and chemical composition of surface films and improves the resistance to local breakdown of the films.

  20. Chimerical categories: caste, race, and genetics.

    Science.gov (United States)

    Sabir, Sharjeel

    2003-12-01

    Is discrimination based on caste equivalent to racism? This paper explores the complex relationship between genetic, race and caste. It also discusses the debate over the exclusion of a discussion of caste-based discrimination at the 2001 World Conference against Racism, Racial Discrimination, Xenophobia and Related Intolerance held in Durban, South Africa. PMID:14768649

  1. Pressure distribution in centrifugal dental casting.

    Science.gov (United States)

    Nielsen, J P

    1978-02-01

    Equations are developed for liquid metal pressure in centrifugal dental casting, given the instantaneous rotational velocity, density, and certain dimensions of the casting machine and casting pattern. A "reference parabola" is introduced making the fluid pressure concept more understandable. A specially designed specimen demonstrates experimentally the reference parabola at freezing. PMID:355283

  2. Low cycle fatigue in ductile cast iron.

    Czech Academy of Sciences Publication Activity Database

    Obrtlík, Karel; Polák, Jaroslav; Dorazil, E.; V?chet, S.; Švejcar, J.

    Kitakyushu : Kyushu Institute of Technology, 1993, s. 85-90. [International Conference on Mechanical Behaviour of Ductile Cast Iron and Other Cast Iron and Other Cast Metals. Kitakyushu (JP), 30.07.1993-01.08.1993] R&D Projects: GA AV ?R IAA241105

  3. Inoculation Effects of Cast Iron

    Directory of Open Access Journals (Sweden)

    E. Fra?

    2012-12-01

    Full Text Available The paper presents a solidification sequence of graphite eutectic cells of A and D types, as well as globular and cementite eutectics. The morphology of eutectic cells in cast iron, the equations for their growth and the distances between the graphite precipitations in A and D eutectic types were analyzed. It is observed a critical eutectic growth rate at which one type of eutectic transformed into another. A mathematical formula was derived that combined the maximum degree of undercooling, the cooling rate of cast iron, eutectic cell count and the eutectic growth rate. One type of eutectic structure turned smoothly into the other at a particular transition rate, transformation temperature and transformational eutectic cell count. Inoculation of cast iron increased the number of eutectic cells with flake graphite and the graphite nodule count in ductile iron, while reducing the undercooling. An increase in intensity of inoculation caused a smooth transition from a cementite eutectic structure to a mixture of cementite and D type eutectic structure, then to a mixture of D and A types of eutectics up to the presence of only the A type of eutectic structure. Moreover, the mechanism of inoculation of cast iron was studied.

  4. Bronchial cast: a case report

    OpenAIRE

    Somani, S. S.; Naik, C. S.

    2008-01-01

    We present a case of a child who presented with respiratory distress mimicking foreign body aspiration which was treated by bronchoscopic extraction of bronchial cast. Early interventional bronchoscopy in management of plastic bronchitis, though difficult, provides an immediate benefit and good prognosis especially in patients with no underlying cardiopulmonary morbidity.

  5. Properties of cast amorphous microwire

    International Nuclear Information System (INIS)

    The cast amorphous glass-coated microwires with different magnetostriction constant were investigated. Microwires were produced of these alloys by the Ulitovsky - Taylor method. We explain the experimental data in the area of study natural ferromagnetic resonance, giant magneto-impedance and domain structures. (authors)

  6. Advanced Lost Foam Casting Technology

    Energy Technology Data Exchange (ETDEWEB)

    Charles E. Bates; Harry E. Littleton; Don Askeland; Taras Molibog; Jason Hopper; Ben Vatankhah

    2000-11-30

    This report describes the research done under the six tasks to improve the process and make it more functional in an industrial environment. Task 1: Pattern Pyrolysis Products and Pattern Properties Task 2: Coating Quality Control Task 3: Fill and Solidification Code Task 4: Alternate Pattern Materials Task 5: Casting Distortion Task 6: Technology Transfer

  7. Graphite Formation in Cast Iron

    Science.gov (United States)

    Stefanescu, D. M.

    1985-01-01

    In the first phase of the project it was proven that by changing the ratio between the thermal gradient and the growth rate for commercial cast iron samples solidifying in a Bridgman type furnace, it is possible to produce all types of graphite structures, from flake to spheroidal, and all types of matrices, from ferritic to white at a certain given level of cerium. KC-135 flight experiments have shown that in a low-gravity environment, no flotation occurs even in spheroidal graphite cast irons with carbon equivalent as high as 5%, while extensive graphite flotation occurred in both flake and spheroidal graphite cast irons, in high carbon samples solidified in a high gravity environment. This opens the way for production of iron-carbon composite materials, with high carbon content (e.g., 10%) in a low gravity environment. By using KC-135 flights, the influence of some basic elements on the solidification of cast iron will be studied. The mechanism of flake to spheroidal graphite transition will be studied, by using quenching experiments at both low and one gravity for different G/R ratios.

  8. Cern Axion Solar Telescope (CAST)

    CERN Multimedia

    2002-01-01

    The CERN Solar Axion Telescope, CAST, aims to shed light on a 30-year-old riddle of particle physics by detecting axions originating from the 15 million degree plasma in the Sun 's core. Axions were proposed as an extension to the Standard Model of particle physics to explain why CP violation is observed in weak but not strong interactions.

  9. Modelling reinforcement corrosion in concrete

    DEFF Research Database (Denmark)

    Michel, Alexander; Geiker, Mette Rica

    2012-01-01

    A physio-chemical model for the simulation of reinforcement corrosion in concrete struc-tures was developed. The model allows for simulation of initiation and subsequent propaga-tion of reinforcement corrosion. Corrosion is assumed to be initiated once a defined critical chloride threshold is reached causing the formation of anodic and cathodic regions along the reinforcement. Critical chloride thresholds, randomly distributed along the reinforcement sur-face, link the initiation and propagation phase of reinforcement corrosion. To demonstrate the potential use of the developed model, a numerical example is pre-sented, that illustrates the formation of corrosion cells as well as propagation of corrosion in a reinforced concrete structure.

  10. Scope on Safety: Combating corrosion

    Science.gov (United States)

    Ken Roy

    2009-07-01

    Corrosion is a broad term that applies when something is being broken down due to a chemical reaction. Rust or wet corrosion is a specific type of corrosion where iron or steel reacts with water. Science teachers often find that over time, laboratory equipment made of metal may tend to look dull and have symptoms of corrosion. In fact, in certain instances, such equipment may become unsafe to use and provide bogus data results on student experiments. There are several strategies that can be used to address corrosion of lab equipment. This article describes some approaches to combating corrosion.

  11. Retinal Vascular Changes are a Marker for Cerebral Vascular Diseases.

    Science.gov (United States)

    Moss, Heather E

    2015-07-01

    The retinal circulation is a potential marker of cerebral vascular disease because it shares origin and drainage with the intracranial circulation and because it can be directly visualized using ophthalmoscopy. Cross-sectional and cohort studies have demonstrated associations between chronic retinal and cerebral vascular disease, acute retinal and cerebral vascular disease, and chronic retinal vascular disease and acute cerebral vascular disease. In particular, certain qualitative features of retinopathy, retinal artery occlusion, and increased retinal vein caliber are associated with concurrent and future cerebrovascular events. These associations persist after accounting for confounding variables known to be disease-causing in both circulations, which supports the potential use of retinal vasculature findings to stratify individuals with regards to cerebral vascular disease risk. PMID:26008809

  12. Hot corrosion of low cobalt alloys

    International Nuclear Information System (INIS)

    The hot corrosion attack susceptibility of various alloys as a function of strategic materials content are investigated. Preliminary results were obtained for two commercial alloys, UDIMET 700 and Mar-M 247, that were modified by varying the cobalt content. For both alloys the cobalt content was reduced in steps to zero. Nickel content was increased accordingly to make up for the reduced cobalt but all other constituents were held constant. Wedge bar test samples were produced by casting. The hot corrosion test consisted of cyclically exposing samples to the high velocity flow of combustion products from an air-fuel burner fueled with jet A-1 and seeded with a sodium chloride aqueous solution. The flow velocity was Mach 0.5 and the sodium level was maintained at 0.5 ppm in terms of fuel plus air. The test cycle consisted of holding the test samples at 900 C for 1 hour followed by 3 minutes in which the sample could cool to room temperature in an ambient temperature air stream

  13. Ultrasonic inspection of nodular cast iron insert edge distance using curved linear PA-probe

    International Nuclear Information System (INIS)

    Nuclear fuel disposal canisters consist of a copper tube and a cast iron insert. The copper tube is designed for corrosion protection. The design and use of the nodular cast iron insert is based on strength and fracture mechanic aspects and it is the load carrying part of the structure. The preliminary acceptance criteria for the cast iron insert are under study. There are several aspects in accepting the inspection results of nodular cast iron insert for use. One aspect among others is the position of the edge which is nearest to surface. In an earlier study this was stated to have a tolerance of edge position ± 5 mm. There have been studies both on eccentricity and the real position of the nearest edge tolerances. To determine the edge position, different ultrasonic techniques were tested using a curved linear PA-probe. To evaluate whether the distance variation is within the tolerance limit, the real geometrical nominal distance must be computed. Because the tolerances of the cast iron insert and its internal geometry can give a large variation in the edge position, these must be carefully evaluated. The applied ultrasonic system is a 128 element phased array equipment. The used probe is curved and adjusted to curvature of the cast iron insert. The curved probe was designed to inspect the edge of the channel with one long axial line scanning. During line scanning the phased array probe does at the same time electronical scanning. To optimize this electronic scanninning. To optimize this electronic scanning, three different ultrasonic techniques were used. This evaluation of edge distance was tested in four inspections of real size cast iron inserts. It was seen that the variation of the edge position is about 1 to 12 mm in radial direction (straightness) and in circumferential direction about 2 to 8 mm (twist) in range of about 4 m. (orig.)

  14. Atmospheric corrosion in nuclear waste storage; Corrosion atmospherique en entreposage

    Energy Technology Data Exchange (ETDEWEB)

    Mazaudier, F.; Feron, D. [CEA-CEREM, Lab. d' Etude de la Corrosion Aqueuse, Gif-sur-Yvette (France); Baklouti, M.; Midoux, N. [CEA-CEREM, Lab. d' Etude de la Corrosion Aqueuse, Gif-sur-Yvette (France); Lab. des Sciences du Genie Chimique, CNRS-ENSIC, Nancy (France)

    2001-04-01

    The following topics were dealt with: storage of conditioned radioactive wastes in metallic containers, atmospheric corrosion effects, long-term behavior prediction, numerical modelling of surface corrosion effects under thermohygrometric fluctuations according ISO/DIS 9223.

  15. Green Rusts and Their Relationship to Iron Corrosion; a Key Role in Microbially Influenced Corrosion

    International Nuclear Information System (INIS)

    Moessbauer spectroscopy (MS) has often been used to characterise double-layered hydroxysalts usually named green rusts (GR) and to follow their Fe(II)/Fe(III) ratio during the oxidation process of Fe(OH)2 in the presence of aggressive anions such as Cl-, SO42-, CO32-,.... They are intermediate compounds between the initial metal Fe(0) via the Fe(II) and the final Fe(III) (oxyhydr)oxides constituting the usual rusts. E-pH Pourbaix diagrams of iron for predicting the aqueous corrosion conditions of iron-based materials are determined by monitoring the electrode potential Eh and pH vs. time. The crystal structure of GRs, in any case constituted of layers of [FeII(1-x)FeIIIx (OH)2]x+ that alternate with interlayers [(x/n)An-.(mx/n)H2O]x- made of An- anions and water molecules, are presented. Several examples of the role of GRs are discussed, from chloride pitting of concrete reinforcing bars to bacterial corrosion of cast iron in water pipes or steel sheet piles in harbours. The efficiency of corrosion inhibitors like phosphate and their relationship to the oxidation of GRs are presented from basic MS studies. But most importantly, the evidence by MS of the dissimilatory reduction of a common ferric oxyhydroxide, ?-FeOOH lepidocrocite, into a GR by the action of a bacterium, Shewanella py the action of a bacterium, Shewanella putrefaciens, opens the path through which microbially influenced corrosion (MIC) operates. A cycling of aerobic and anaerobic conditions is necessary where GRs but also magnetite play likely the key role.

  16. CASTE SYSTEMS IN INDIA: AN OVERVIEW

    Directory of Open Access Journals (Sweden)

    Amit Kumar

    2014-08-01

    Full Text Available 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 Indian life

  17. Plasticity and corrosion resistance of magnesium alloy WE43

    OpenAIRE

    Walke, W.; Hadasik, E.; Przondziono, J.; Kuc, D.; Bednarczyk, I.; Niewielski, G.

    2011-01-01

    Purpose: The purpose of this study was to assess the extent to which magnesium alloy WE43 is susceptible to metal forming and to assess its structure after hot forming. Corrosion resistance evaluation of WE43 alloy in NaCl solutions, after casting and extrusion forging, was also made. Basic groups of magnesium alloys for plastic forming were characterised.Design/methodology/approach: Formability of magnesium alloy WE43 was determined on the ground of uni-axial compression tests in the tempera...

  18. Intergranular stress corrosion sensitivity in stabilized stainless steels

    International Nuclear Information System (INIS)

    Stabilized stainless steels are used in ASEA-ATOM BWR's in a number of forged and casted components, viz. valve housings. Samples of steels that are Ti-stabilized have been analyzed for carbon, and then CERT-tested for intergranular stress corrosion (IGSCC). The steels tested are Sandvik 8R30 and VEW A700. The medium was water with 8 ppm O2 and at 286 degreeC, and a feed conductivity of less than 0.1?Scm-1. The tests show that the zone near welds in these stabilized steels which in strongly oxidizing acids are sensitive to knife line attack, are also in BWR systems sensitive to IGSCC. This type of corrosion can be inhibited by minimizing the carbon content of the steels. (Aa)

  19. The design of an instrumented rebar for assessment of corrosion in cracked reinforced concrete

    DEFF Research Database (Denmark)

    Pease, Bradley Justin; Geiker, Mette Rica

    2011-01-01

    An instrumented rebar is presented which was designed to have a realistic mechanical performance and to provide location dependent measurements to assess the environment with regards to reinforcement corrosion. The instrumented rebar was constructed from a hollowed 10 mm nominal diameter standard rebar with 17 electronically isolated corrosion sensors. Instrumented and standard rebars were cast into concrete beams and bending cracks were induced and held open using steel frames. Epoxy impregnation was used to assess and compare cracks in the concrete around the instrumented and standard rebar. As bending-induced cracks reached the reinforcement, slip and separation occurred along the concrete-reinforcement interface. Cracks in the concrete surrounding standard and instrumented rebars are largely similar in appearance; however, sensors protruding from the instrumented rebar reduced the separation between the steel and concrete. Cracked beams with cast-in instrumented and standard rebars were ponded with a 10\\% chloride solution and the open circuit corrosion potential (OCP) of the 17 sensors was measured for up to 62 days. Measurements from the individual sensors indicate when and where active corrosion may be thermodynamically favored based upon the local environmental conditions. Results indicated the length along the instrumented rebar where active corrosion was thermodynamically favored increased with exposure time due to the increased aggressivity of the local environmental conditions.

  20. Behaviour of oxygen in cast irons

    Directory of Open Access Journals (Sweden)

    T. Elbel

    2008-10-01

    Full Text Available Purpose: Cast irons are the basic structural material and they form 75% of the world production of castings. The crystallization of cast iron and the formation of graphite are a complex process influencing by oxygen. The aim of our study is to identify the role of oxygen in Fe-C-Si melts.Design/methodology/approach: Continuous comparison of changes in metal composition and oxygen activity during melting, pouring, and solidification of experimental castings, using metallographic methods and microanalysis. Determination of total oxygen content in cast iron by the high temperature extraction method.Findings: Oxygen activity in graphitic cast irons is determined during manufacture of liquid metal and its pouring mainly by carbon and silicon activities. Silicon deoxidates cast irons at lower temperatures, at higher temperatures this function is taken over by carbon. Logarithmic dependences of oxygen activity on temperature for individual graphite forms (lamellar, vermicular, and spheroidal ones have been obtained. Determination of total oxygen content in cast iron on the other hand gives valuable information for controlling surface and internal quality of cast irons.Practical implications: Possibility of control the cast iron structure and graphitization during crystallization by monitoring the oxygen content with an indirect method of oxygen activity measurement in the melt before metal pouring the mould.Originality/value: The used method gives reproducible results which are comparable under different conditions of metal melting and pouring. Obtained knowledge extends the understanding in the field of cast irons crystallization by less known influence of oxygen.

  1. Prediction of Part Distortion in Die Casting

    Energy Technology Data Exchange (ETDEWEB)

    R. Allen Miller

    2005-03-30

    The die casting process is one of the net shape manufacturing techniques and is widely used to produce high production castings with tight tolerances for many industries. An understanding of the stress distribution and the deformation pattern of parts produced by die casting will result in less deviation from the part design specification, a better die design and eventually more productivity and cost savings. This report presents methods that can be used to simulate the die casting process in order to predict the deformation and stresses in the produced part and assesses the degree to which distortion modeling is practical for die casting at the current time. A coupled thermal-mechanical finite elements model was used to simulate the die casting process. The simulation models the effect of thermal and mechanical interaction between the casting and the die. It also includes the temperature dependant material properties of the casting. Based on a designed experiment, a sensitivity analysis was conducted on the model to investigate the effect of key factors. These factors include the casting material model, material properties and thermal interaction between casting and dies. To verify the casting distortion predictions, it was compared against the measured dimensions of produced parts. The comparison included dimensions along and across the parting plane and the flatness of one surface.

  2. Fabrication of sacrificial anode cathodic protection through casting method

    International Nuclear Information System (INIS)

    Aluminum is one of the few metals that can be cast by all of the processes used in casting metals. These processes consist of die casting, permanent mold casting, sand casting (green sand and dry sand), plaster casting, investment casting, and continuous casting. Other processes such as lost foam, squeeze casting, and hot isostatic pressing are also used. Permanent mold casting method was selected in which used for fabricating of sacrificial anode cathodic protection. This product was ground for surface finished and fabricated in the cylindrical form and reinforced with carbon steel at a center of the anode. (Author)

  3. Casting Characteristics of Aluminum Die Casting Alloys; FINAL

    International Nuclear Information System (INIS)

    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

  4. Corrosion testing facilities in India

    International Nuclear Information System (INIS)

    Major types of corrosion tests, establishment of specifications on corrosion testing and scope of their application in practice are briefly described. Important organizations in the world which publish specifications/standards are listed. Indian organizations which undertake corrosion testing and test facilities available at them are also listed. Finally in an appendix, a comprehensive list of specifications relevant to corrosion testing is given. It is arranged under the headings: environmental testing, humidity tests, salt spray/fog tests, immersion tests, specification corrosion phenomena, (tests) with respect to special corrosion media, (tests) with respect to specific corrosion prevention methods, and specific corrosion tests using electrical and electrochemical methods (principles). Each entry in the list furnishes information about: nature of the test, standard number, and its specific application. (M.G.B.)

  5. Progenitor cells and vascular endothelium

    OpenAIRE

    Briasoulis, A.; Tousoulis, D.; Antoniades, C.; Stefanadis, C.

    2011-01-01

    Endothelial progenitor cells (EPCs) are under investigation due to their association with vascular injury. In response to chemotactic stimuli they are mobilized from bone-marrow and non-bone marrow sites, they migrate, adhere and home to the injured vessel. Numerous molecular and cellular pathways participate and converge to the EPCs mediated vascular repair. However, the exact phenotypic properties, modes of functions and effects in vascular diseases and particularly in atherosclerosis are u...

  6. Local audit in vascular surgery.

    OpenAIRE

    Clyne, C. A.

    1990-01-01

    A 2-year audit of the Southampton Vascular Unit showed marked discrepancies in workload from nationally accepted figures. All forms of reconstructive surgery except emergency aortic aneurysm grafting were performed more frequently than expected. The vascular population is elderly and at high risk from major surgery. Mortality was appreciable in all major vascular procedures and usually cardiac or renal related. The elderly population and resulting workload is likely to increase in the near fu...

  7. A SURVEY OF SOIL FOR DETERMINATION OF CORROSION FACTORS ON WATER PIPE WITHIN TEHRAN AREA

    OpenAIRE

    Razeghi, M.; Jamshidnia; Behnoud

    1980-01-01

    Corrosion of water and gas pipes is not desirable from the view point of health, economy and nuisances. There are many factors in soil which attack the metal pipes for corrosion. (Steel, Cast, Iron and Like). That is why the designer of metal pipes for conveyance of metal pipes for conveyance of water and gas should be aware of these factors and pay nutmost care in selection of pipes and protection facilities. The results of research and surveys in different areas of the world indicate that t...

  8. Blood and vascular diseases

    International Nuclear Information System (INIS)

    The identification of regulatory stromal cell-megakaryocyte interactions would add significantly to the understanding of the regulation of platelet production. Therefore, studies are under way to make comparative biochemical and ultrastructural studies of megakaryocytes in culture and in bone marrow and of their relationships to other cells. In addition, new studies are underway to investigate interactions between platelets and the normal or diseased vessel wall. One of the aims is to determine if vascular lesions can be detected by positron emission tomography using platelets labeled with positron emitting radioisotopes such as 68Ga

  9. In vitro crevice corrosion behavior of implant materials.

    Science.gov (United States)

    Sutow, E J; Jones, D W; Milne, E L

    1985-05-01

    The crevice corrosion susceptibility of cold-worked Type 316LVM stainless steel, cast Co-Cr-Mo, wrought Co-Cr-W-Ni, non-nitrided and nitrided Ti-6Al-4V ELI, and c.p. Ti, Grades 1 and 4, was studied in vitro by means of a crevice cell. Occlusion was created by interfacing a disc specimen and a Teflon bar. Specimens were mechanically prepared through 2-4 micron Al2O3 and passivated in 30% HNO3, followed by steam sterilization. Tests were performed in a deaerated Ringer's solution, maintained at pH = 7 and 37 degrees C. Anodic polarization was conducted potentiostatically at pre-selected levels, and resultant currents were monitored: stainless steel, 50 and 100 mV (S.C.E.), 450 min; non-stainless materials, 600 mV, 1000 min. Results for the stainless steel demonstrated that a HNO3 passivation treatment reduced its crevice corrosion susceptibility. For the non-stainless steel materials, no crevice corrosion susceptibility was observed, although a dulling and discoloration of c.p. Ti was evident. Recognizing that 600 mV is in excess of the O2 reduction potential in vivo, it was concluded that, in the absence of fretting, implants of these non-stainless steel materials would not experience significant corrosion loss under crevice conditions. PMID:3858307

  10. Soil corrosion monitoring near a pipeline under CP

    Energy Technology Data Exchange (ETDEWEB)

    Bullard, Sophie J.; Covino, Bernard S., Jr.; Cramer, Stephen D.; Holcomb, Gordon R.; Ziomek-Moroz, Margaret; Locke, M.L. (NW Natural); Warthen, M.R. (NW Natural); Kane, Russell D. (Intercorr International Inc.); Eden, Dawn C. (Intercorr International Inc.)

    2005-01-01

    Electrochemical noise (EN), linear polarization resistance (LPR), and harmonic distortion analysis (HDA) were used with three-electrode probes to monitor the corrosion occurring in soil in dry and wet conditions near a gas pipeline under cathodic protection. The test site was a cathodic protection (CP) test station where impressed current CP was applied to a 2 in. (5.1 cm) diameter FBE coated steel pipe using an 84 in. (0.2 m) TA-2 high-silicon cast iron anode. Electrochemical measurements were made at three locations, two inside the CP field and one outside the CP field. Electrochemical measurements were first made with the CP system off to establish the baseline corrosion and then with increasing levels of CP. The degree of protection was based on polarized potential and the adequacy of protection was determined by depolarization measurements. CP of an adjacent pipeline did not affect the measurement of either corrosion rate or pitting factor when using buried soil corrosion probes and the EN, LPR, and HDA techniques.

  11. Rapid casting and new technologies in investment casting

    OpenAIRE

    Claudia Marcela Sánchez R; Carlos Julio Cortés Rodríguez

    2010-01-01

    Rapid prototyping is a manufacturing process which is different to traditional methods as material is not removed or formed but added to obtain the designed pieces. It is not lust used for manufacturing finished products but in manufacturing tooling for speeding up other manufacturing processes. This paper introduces rapid prototyping as a support technique for the lost wax process (investment casting). It gives a brief description of the different techniques implemented to date and materials...

  12. Neutron diffraction study of Levantine Middle Bronze Age cast axes

    International Nuclear Information System (INIS)

    A neutron diffraction study on 6 Middle Bronze Age axes, cast from tin bronze or from arsenical copper, has been carried out using the ENGIN-X beamline at ISIS. The gauge volumes dimensions were 4x4x10mm3; data were collected along the lengths of the objects in their central parts, as well as on the blades, in order to establish the spatial phase contents. Average phase fractions were determined by Rietveld analysis. The main phases identified were solid solutions, corrosion phases and metallic Pb inclusions. We have observed distributions of lattice constants of the solid solutions Cu-Sn, and Cu-As inside each gauge volume in the central parts of the axes due to segregation, or liquation effects. However, the Cu-Sn variations were significantly less pronounced in comparison with typical inhomogeneity effects in as cast objects. The results indicate that the studied Middle Bronze Age axes were probably treated at high temperatures for homogenization necessary for generating sufficient hardness, especially on the blades.

  13. Effect of microstructure on corrosion behavior of Ag-30Cu-27Sn alloy in vitro media

    International Nuclear Information System (INIS)

    Highlights: • High cooling rates decrease the number of Ag intermetallic particles in Cu-rich phase. • Increasing cooling rate improves corrosion behavior of Ag-30Cu-27Sn dental alloy. • Cathode/anode ratio in Cu-rich phases determines the corrosion behavior of alloy. - Abstract: In the present work, three simple heat treatment cycles were used to study the effects of microstructure on electrochemical corrosion behavior of Ag-30Cu-27Sn dental alloy. The electrochemical impedance spectroscopy (EIS) measurements and potentiodynamic polarization tests were carried out to investigate the corrosion behavior of as-cast and heat treated samples in synthetic saliva solution. The presence of intermetallic compounds were studied by X-ray diffraction method (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray detector (EDAX). The microstructural observations and electrochemical corrosion results revealed that, increasing the cooling rate improves the corrosion behavior of under investigation samples. Improvement of the corrosion behavior is attributed to reducing the area of fine distributed Ag3Sn islands in the Cu-rich matrix which decrease the cathode/anode ratio of microgalvanic cells

  14. Effect of microstructure on corrosion behavior of Ag-30Cu-27Sn alloy in vitro media

    Energy Technology Data Exchange (ETDEWEB)

    Salehisaki, Mehdi, E-mail: mehdisasaki@ut.ac.ir [Department of Materials Science and Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Aryana, Maryam, E-mail: maryam.aryana@yahoo.com [AGSP Engineering Company, Biomaterial Research Unit, R.N: 12786 Kerman (Iran, Islamic Republic of)

    2014-04-01

    Highlights: • High cooling rates decrease the number of Ag intermetallic particles in Cu-rich phase. • Increasing cooling rate improves corrosion behavior of Ag-30Cu-27Sn dental alloy. • Cathode/anode ratio in Cu-rich phases determines the corrosion behavior of alloy. - Abstract: In the present work, three simple heat treatment cycles were used to study the effects of microstructure on electrochemical corrosion behavior of Ag-30Cu-27Sn dental alloy. The electrochemical impedance spectroscopy (EIS) measurements and potentiodynamic polarization tests were carried out to investigate the corrosion behavior of as-cast and heat treated samples in synthetic saliva solution. The presence of intermetallic compounds were studied by X-ray diffraction method (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray detector (EDAX). The microstructural observations and electrochemical corrosion results revealed that, increasing the cooling rate improves the corrosion behavior of under investigation samples. Improvement of the corrosion behavior is attributed to reducing the area of fine distributed Ag{sub 3}Sn islands in the Cu-rich matrix which decrease the cathode/anode ratio of microgalvanic cells.

  15. Corrosion resistance of AZ31 alloy after plastic working in NaCl solutions

    Directory of Open Access Journals (Sweden)

    W. Walke

    2011-04-01

    Full Text Available Purpose: The purpose of the study was to assess corrosion resistance of magnesium alloy AZ31 (Mg-Al-Zn alloy after plastic working in NaCl solutions. It presents currently applied methods of magnesium alloys plastic working. Basic groups of magnesium alloys that are used for plastic working have been discussed.Design/methodology/approach: Corrosion tests of AZ31 alloy were carried out in solution with concentration of 0.01-2 M NaCl with application of the system for electrochemical tests VoltaLab®PGP201. Resistance to electrochemical corrosion was evaluated on the ground of registered anodic polarisation curves by means of potentiodynamic method. Immersion tests were carried out in NaCl solutions in the time of 1-5 days. Scanning microscopy enabled to present microstructure of AZ31 after immersion tests.Findings: Results of all carried out tests explicitly prove deterioration of corrosion properties of magnesium alloy AZ31 with the increase in molar concentration of NaCl solution.Practical implications: It was determined that irrespective of molar concentration of NaCl solution pitting corrosion was found in the tested alloy. It proves that application of protective coating on elements made of the tested alloy is necessary.Originality/value: Literature gives the results of corrosion tests with reference to cast alloy AZ31. Tests of corrosion resistance of hot rolled AZ31 in chloride solutions have been made for the first time.

  16. Electrochemical evaluation of corrosion inhibitors for repairing of highway transportation infrastructures

    Science.gov (United States)

    Lee, K. Wayne; Cao, Yong; Brown, Richard; Guo, Rui-Guang

    2000-06-01

    Among the methods to tackle corrosion of steel reinforcement in highway transportation infrastructure, using corrosion inhibitors has been identified as the most easily and economically applied technique. This study used Electrochemical Impedance Spectroscopy (EIS) to evaluate four corrosion inhibitors in simulated pore solution (SPS) and saturated calcium hydroxide solution (CHS). Three promising inhibitors were identified. It was also found that the electrochemical laboratory test was practical to evaluate corrosion inhibitors quickly and effectively in simulated concrete solutions. A simulated field concrete repair method was devised in order to verify the developed electrochemical laboratory test result. Sixty-three concrete short beam specimens were used. The embedded steel rebars were exposed to chloride environment and electrochemically monitored in accordance with the ASTM G109 procedure. After active corrosion of the upper rebars was detected, the chloride- contaminated concrete was removed. The three aforementioned promising inhibitors were applied to corroded rebars, and new concrete was cast. These rebars were electrochemically monitored to evaluate the effectiveness of corrosion inhibitors for corrosion control. It was found that there was a good correlation between these two test results, and the most effective inhibitor was finally identified.

  17. Radionuclide corrosion studies of tantalum

    International Nuclear Information System (INIS)

    The corrosion of tantalum in 96% sulfuric acid and the influence of nitric and hydrochloric acid were investigated by means of a radionuclide method. There is nearly uniform surface attack in all systems investigated. The corrosion rates in sulfuric acid exceed a level of 1 mm/a at 250degC. The addition of nitric acid enhances the passivity of tantalum and the corrosion rate drops by a factor of 2-3. No stress corrosion cracking was observed. (author)

  18. Corrosion-resistant metal surfaces

    Science.gov (United States)

    Sugama, Toshifumi (Wading River, NY)

    2009-03-24

    The present invention relates to metal surfaces having thereon an ultrathin (e.g., less than ten nanometer thickness) corrosion-resistant film, thereby rendering the metal surfaces corrosion-resistant. The corrosion-resistant film includes an at least partially crosslinked amido-functionalized silanol component in combination with rare-earth metal oxide nanoparticles. The invention also relates to methods for producing such corrosion-resistant films.

  19. Corrosion of steel in concrete

    OpenAIRE

    Tuutti, Kyo?sti

    1982-01-01

    The research work that is presented in this thesis aims at mapping out the various mechanisms which control the process of steel corrosion in concrete. The process of corrosion is illustrated with a schematic model where the service life is divided into a period of initiation and a period of propagation. The time up to the initiation of the corrosion process is determined by the flow of penetrating substances into the concrete cover and by the threshold concentration for corrosion to start. T...

  20. Corrosion experiment off South Uist

    Energy Technology Data Exchange (ETDEWEB)

    Picken, M.J.; Bowers, R.

    1981-12-01

    The results of a experiment to investigate the corrosion of mild steel in seawater in a wave energy area of the Outer Hebrides are reported. Cathodic protection of the steel specimen was effected using a zinc anode. Measurements of corrosion potential, corrosion current, water speed and water temperature were made. An equation linking the corrosion current, water speed and time of exposure has been derived.

  1. Inner surface roughness of complete cast crowns made by centrifugal casting machines.

    Science.gov (United States)

    Ogura, H; Raptis, C N; Asgar, K

    1981-05-01

    Six variables that could affect the surface roughness of a casting were investigated. The variables were (1) type of alloy, (2) mold temperature, (3) metal casting temperature, (4) casting machine, (5) sandblasting, and (6) location of each section. It was determined that the training portion of a complete cast crown had rougher surfaces than the leading portion. Higher mold and casting temperatures produced rougher castings, and this effect was more pronounced in the case of the base metal alloy. Sandblasting reduced the roughness, but produced scratched surfaces. Sandblasting had a more pronounced affect on the surface roughness of the base metal alloy cast either at a higher mold temperature or metal casting temperature. The morphology and the roughness profile of the original cast surface differed considerably with the type of alloy used. PMID:7012322

  2. Plasticity and corrosion resistance of magnesium alloy WE43

    Directory of Open Access Journals (Sweden)

    W. Walke

    2011-09-01

    Full Text Available Purpose: The purpose of this study was to assess the extent to which magnesium alloy WE43 is susceptible to metal forming and to assess its structure after hot forming. Corrosion resistance evaluation of WE43 alloy in NaCl solutions, after casting and extrusion forging, was also made. Basic groups of magnesium alloys for plastic forming were characterised.Design/methodology/approach: Formability of magnesium alloy WE43 was determined on the ground of uni-axial compression tests in the temperature from 200 to 450°C and with deformation rate within the range from 0.01 to 10 s-1. The structure of the alloy after hot forming was presented. Corrosion tests of magnesium alloy WE43 were carried out in solutions with concentration of 0.01-2 M NaCl with application of electrochemical testing system VoltaLab®PGP201. Electrochemical corrosion resistance was evaluated on the ground of registered anodic polarisation curves by means of potentiodynamic method.Findings: It was proved that resistance of magnesium alloy WE43 in temperature range from 200 to 300°C is limited. It was found that recrystallization begins during strain application at the temperature of 350°C. Strain at the temperature of 450°C guarantees full recrystallization of the alloy. The results of carried out corrosion tests explicitly show deterioration of corrosion characteristics of magnesium alloy WE43 together with increase of molar concentration of NaCl solution.Practical implications: The tests results regarding the effect of strain parameters on magnesium alloy WE43 formability may be employed in preparation of metal forming technology for the alloy. In corrosion tests it was proved that irrespective of molar concentration of NaCl solution, pitting corrosion is present in the tested alloy. It proves it is necessary to apply protective layers on elements made of WE43 alloy, irrespective of its state of delivery.Originality/value: Tests of technological plasticity enabled to determine the dependence of yield stress on temperature and rate of strain. Electrochemical corrosion tests showed that WE43 alloy obtained in extrusion features slightly higher corrosion characteristics.

  3. Characterization of the interface of two dental palladium alloys cast on a prefabricated implant gold cylinder

    International Nuclear Information System (INIS)

    The interface between two dental alloys (Pd-Cu-Ga, Pd-Ga) cast-to a prefabricated gold cylinder in two thicknesses (1, 2 mm) was investigated. Specimens were observed in optical and scanning electron microscopes. Line scan microanalysis by EDS was performed and polarization curves were taken. Gold cylinders shape was preserved. Characteristic elongated grains were detected at the gold cylinder alloy. The boundaries between the cylinder and the cast-to alloys were distinct. The 2 mm thick Pd-Ga alloy cast to the gold cylinder revealed high porosity at the interface, while the rest of the subgroups showed no or negligible porosity. Line scan analysis revealed the gradual diffusion of the main elements of each alloy in the structure of the gold cylinder and vice-versa in a 3-5 ?m zone. Corrosion behaviour was estimated by cyclic polarization tests in 1 M lactic acid. The polarization curves showed negative hysteresis. In the reverse anodic scan the current density was less than that for the forward scan. This fact confirms that all the tested materials are not susceptible to corrosion in 1 M lactic acid.

  4. The cavitational erosion resistance of the B2-type Fe-Al casting alloys

    Directory of Open Access Journals (Sweden)

    R. Jasionowski

    2010-01-01

    Full Text Available The problem of the destruction of turbo-machinery components is very complex, because it consists of processes of erosion and corrosion. The most dangerous factor is the cavitation phenomenon, which is very difficult to eliminate through the use of design solutions. It causes deterioration of the operating characteristics of machinery and equipment, such as water turbines, steam turbines, centrifugal pumps, screw vessels, cylinder liners with water-cooled engines, acoustic probe. The most commonly used method of limiting the destruction of cavitation phenomenon is the optimum choice of parameters of geometric and hydraulic machines, the appropriate design of elements and streamlined flow and providing working conditions of flow devices. The above-mentioned methods by design, the size of flow devices are limited, so better action to prevent the flow of erosion may use the material for greater resistance to erosion and cavitation corrosion is the alloy of intermetallic FeAl phase, which production costs are low compared to cast steel and cast iron alloy based on chromium and nickel.The paper presents results of an investigation carried out for cavitational resistance of the B2-type Fe-Al casting alloys using a flux-impact measuring device. The intermetallic FeAl alloys proved to have good resistance to this type of erosion in comparison to other construction materials, investigated by flux-impact device.

  5. Corrosion Monitoring System

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Russ Braunling

    2004-10-31

    The Corrosion Monitoring System (CMS) program developed and demonstrated a continuously on-line system that provides real-time corrosion information. The program focused on detecting pitting corrosion in its early stages. A new invention called the Intelligent Ultrasonic Probe (IUP) was patented on the program. The IUP uses ultrasonic guided waves to detect small defects and a Synthetic Aperture Focusing Technique (SAFT) algorithm to provide an image of the pits. Testing of the CMS demonstrated the capability to detect pits with dimensionality in the sub-millimeter range. The CMS was tested in both the laboratory and in a pulp and paper industrial plant. The system is capable of monitoring the plant from a remote location using the internet.

  6. Plastics for corrosion inhibition

    CERN Document Server

    Goldade, Victor A; Makarevich, Anna V; Kestelman, Vladimir N

    2005-01-01

    The development of polymer composites containing inhibitors of metal corrosion is an important endeavour in modern materials science and technology. Corrosion inhibitors can be located in a polymer matrix in the solid, liquid or gaseous phase. This book details the thermodynamic principles for selecting these components, their compatibility and their effectiveness. The various mechanisms of metal protection – barrier, inhibiting and electromechanical – are considered, as are the conflicting requirements placed on the structure of the combined material. Two main classes of inhibited materials (structural and films/coatings) are described in detail. Examples are given of structural plastics used in friction units subjected to mechano-chemical wear and of polymer films/coatings for protecting metal objects against corrosion.

  7. Radiography can find corrosion

    International Nuclear Information System (INIS)

    Some of the advantages and limitations of using X-ray techniques to assess the severity of pitting corrosion in copper plumbing services were encountered recently. In an isolated maximum security area the services were run in basement walkways, the copper pipes being laid on brackets which held them clear of the concrete base. The location was ideal for use of X-ray techniques, which offered a means of checking short sections (18'') of the pipework without interrupting the supply. The radiographs indicated that pitting corrosion was widespread and shows the great value of X-ray examination as an aid to corrosion technology in the field, but also highlights the need for a rational interpretation of results in conjunction with other methods of visual and destructive assessment. (author)

  8. Microstructure 2007of WE43 casting magnesium alloy

    Directory of Open Access Journals (Sweden)

    A. Kie?bus

    2007-03-01

    Full Text Available Purpose: WE43 is a high-strength magnesium alloy characterized by good mechanical properties both at an ambient and elevated temperature (up to 300°C. It contains mainly yttrium and neodymium. The aim of this paper is to present the results of research on the microstructure of the WE43 magnesium alloy in an as-cast condition.Design/methodology/approach: For the microstructure observation, a Reichert metallographic microscope MeF2 and a HITACHI S-3400N scanning electron microscope with a Thermo Noran EDS equipped with SYSTEM SIX were used. A qualitative phase analysis was performed with a JEOL JDX-7S diffractometer. Microstrucutral examinations were performed JEOL 3010 transmission electron microscope.Findings: Based on the investigation carried out it was found that the microstructure of WE43 alloy after continuous casting consists of ?-Mg matrix and irregular precipitates of Mg41Nd5, rectangular particles of MgY phase, particles of Mg24Y5, longitudinal precipitates of ? (Mg14Nd2Y compound at grain boundaries and the grain interiors. All of these phases contain yttrium and neodymium. Research limitations/implications: Future researches should contain investigations of the influence of heat treatment parameters on microstructure, corrosion resistance and mechanical properties of WE43 alloy.Practical implications: WE43 magnesium alloy is used in the aircraft industry, for wheels, engine casings, gear box casings and rotor heads in helicopters. Results of investigation may be useful for development casting technology of the Mg-Y-Nd alloys.Originality/value: The results of the researches make up a basis for the next investigations of magnesium alloys with addition of Y and Nd designed to exploitation at temperature to 300°C.

  9. Corrosion resistant PEM fuel cell

    Science.gov (United States)

    Fronk, Matthew Howard (Honeoye Falls, NY); Borup, Rodney Lynn (East Rochester, NY); Hulett, Jay S. (Rochester, NY); Brady, Brian K. NY); Cunningham, Kevin M. (Romeo, MI)

    2011-06-07

    A PEM fuel cell having electrical contact elements comprising a corrosion-susceptible substrate metal coated with an electrically conductive, corrosion-resistant polymer containing a plurality of electrically conductive, corrosion-resistant filler particles. The substrate may have an oxidizable metal first layer (e.g., stainless steel) underlying the polymer coating.

  10. Expansion due to the anaerobic corrosion of iron

    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 vertical storage holes drilled in a series of caverns excavated from the granite bedrock at a depth of about 500 m and surrounded by compacted bentonite clay. The canister design is based on a thick cast inner container, designed to provide mechanical strength and to keep individual fuel bundles at a safe distance from one another, thereby minimising the risk of criticality. The container is fitted inside an inherently corrosion resistant copper overpack that is designed to provide containment over the long timescales required. As part of the safety case for the repository, one of the scenarios being addressed by SKB involves the early mechanical failure of the outer copper overpack, allowing water to enter the outer container and corrode the inner one. One consequence of this failure would be the long-term build up of corrosion product, which could induce stresses in the spent fuel canister. A programme of experimental work was undertaken to investigate the effect of corrosion product formation on the generation of stresses in the outer copper container. This report describes the construction of an apparatus to directly measure the expansion caused by the anaerobic corrosion of ferrous material in a simulated repository environment whilst under representative compressive loads. This apparatus, known as the 'stress cell' consisted of a stack of interleaved carbon steel and copper discs that was subjected to a compressive load simulating the loads expected in a repository and immersed in simulated anoxic groundwater at 69 deg C. The stack was mounted in a rigid frame and a system of levers was used to amplify any expansion caused by corrosion; the expansion of the stack was measured using sensitive displacement transducers. Initially, three cells were set up: two contained alternate carbon steel and copper discs, and the third, a control cell, consisted of alternate stainless steel and copper discs. A slight contraction of the control cell was observed but no expansion was measured in the carbon steel-copper cells. Analytical measurements showed that the corrosion products were magnetite and hydrogen, indicating that anaerobic corrosion was occurring. In a second series of experiments, one experiment was carried out in which carbon steel was replaced with cast iron and in a further experiment air was allowed to enter the test chamber. No expansion was detected in either of these additional experiments. However, expansion was detected when a separate stack of copper and steel washers was corroded in ambient atmospheric conditions under very small compressive loads, and subjected to a wet-dry cycle, demonstrating that the experimental technique was capable of detecting corrosion-induced expansion if it were occurring. In parallel with the stress cell experiments, coupons of mild steel and cast iron were corroded in anoxic, artificial groundwater at 50 deg C and 80 deg C for several months. The coupons were examined using atomic force microscopy (AFM) to determine the mechanical properties and the structure of the corrosion product films, and X-ray photoelectron spectroscopy (XPS) to identify the chemical composition of the film. The report presents Young's modulus, thickness and hardness data for the oxides, which were much more compliant than the magnetite films formed at high temperatures, probably because of their high water content. The report considers the application of the results to assessing the performance of the SKB canister in a repository situation

  11. Expansion due to the anaerobic corrosion of iron

    Energy Technology Data Exchange (ETDEWEB)

    Smart, N.R.; Rance, A.P.; Fennell, P.A.H. [Serco Assurance, Culham Science Centre (United Kingdom)

    2006-12-15

    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 vertical storage holes drilled in a series of caverns excavated from the granite bedrock at a depth of about 500 m and surrounded by compacted bentonite clay. The canister design is based on a thick cast inner container, designed to provide mechanical strength and to keep individual fuel bundles at a safe distance from one another, thereby minimising the risk of criticality. The container is fitted inside an inherently corrosion resistant copper overpack that is designed to provide containment over the long timescales required. As part of the safety case for the repository, one of the scenarios being addressed by SKB involves the early mechanical failure of the outer copper overpack, allowing water to enter the outer container and corrode the inner one. One consequence of this failure would be the long-term build up of corrosion product, which could induce stresses in the spent fuel canister. A programme of experimental work was undertaken to investigate the effect of corrosion product formation on the generation of stresses in the outer copper container. This report describes the construction of an apparatus to directly measure the expansion caused by the anaerobic corrosion of ferrous material in a simulated repository environment whilst under representative compressive loads. This apparatus, known as the 'stress cell' consisted of a stack of interleaved carbon steel and copper discs that was subjected to a compressive load simulating the loads expected in a repository and immersed in simulated anoxic groundwater at 69 deg C. The stack was mounted in a rigid frame and a system of levers was used to amplify any expansion caused by corrosion; the expansion of the stack was measured using sensitive displacement transducers. Initially, three cells were set up: two contained alternate carbon steel and copper discs, and the third, a control cell, consisted of alternate stainless steel and copper discs. A slight contraction of the control cell was observed but no expansion was measured in the carbon steel-copper cells. Analytical measurements showed that the corrosion products were magnetite and hydrogen, indicating that anaerobic corrosion was occurring. In a second series of experiments, one experiment was carried out in which carbon steel was replaced with cast iron and in a further experiment air was allowed to enter the test chamber. No expansion was detected in either of these additional experiments. However, expansion was detected when a separate stack of copper and steel washers was corroded in ambient atmospheric conditions under very small compressive loads, and subjected to a wet-dry cycle, demonstrating that the experimental technique was capable of detecting corrosion-induced expansion if it were occurring. In parallel with the stress cell experiments, coupons of mild steel and cast iron were corroded in anoxic, artificial groundwater at 50 deg C and 80 deg C for several months. The coupons were examined using atomic force microscopy (AFM) to determine the mechanical properties and the structure of the corrosion product films, and X-ray photoelectron spectroscopy (XPS) to identify the chemical composition of the film. The report presents Young's modulus, thickness and hardness data for the oxides, which were much more compliant than the magnetite films formed at high temperatures, probably because of their high water content. The report considers the application of the results to assessing the performance of the SKB canister in a repository situation.

  12. CT in vascular pathologies

    International Nuclear Information System (INIS)

    Since the introduction of helical scanners, CT angiography (CTA) has achieved an essential role in many vascular applications that were previously managed with conventional angiography. The performance of CTA is based on the accurate selection of collimation width, pitch, reconstruction spacing and scan delay, which must be modulated on the basis of the clinical issue. However, the major improvement of CT has been provided by the recent implementation of many post-processing techniques, such as multiplanar reformatting, shaded surface display, maximum intensity projections, 3D perspectives of surface and volume rendering, which simulate virtual intravascular endoscopy. The integration of the potentialities of the scanner and of the image processing techniques permitted improvement of: (a) the evaluation of aneurysms, dissection and vascular anomalies involving the thoracic aorta; (b) carotid artery stenosis; (c) aneurysms of abdominal aorta; (d) renal artery stenosis; (e) follow-up of renal artery stenting; and (f) acute or chronic pulmonary embolism. Our experience has shown that the assessment of arterial pathologies with CTA requires the integration of 3D post-processing techniques in most applications. (orig.)

  13. Corrosion of Iron Experiment

    Science.gov (United States)

    The Materials Science and Technology Teacher's Workshop (MAST) provides this demonstration on corrosion. The laboratory exercise will allow students the opportunity to "observe the electrochemical nature of the changes in an iron nail when it corrodes and to investigate methods to protect it." Ways of preventing corrosion include protecting the metal with a more active metal and excluding oxygen and moisture from the material's surface with a protective coating. The lesson includes a step by step explanation of the laboratory procedure, discussion questions and teacher notes.

  14. Search for chameleons with CAST

    CERN Document Server

    Anastassopoulos, V; Aune, S; Barth, K; Belov, A; Bräuninger, H; Cantatore, G; Carmona, J M; Cetin, S A; Christensen, F; Collar, J I; Dafni, T; Davenport, M; Desch, K; Dermenev, A; Eleftheriadis, C; Fanourakis, G; Ferrer-Ribas, E; Friedrich, P; Galán, J; García, J A; Gardikiotis, A; Garza, J G; Gazis, E N; Geralis, T; Giomataris, I; Hailey, C; Haug, F; Hasinoff, M D; Hofmann, D H H; Iguaz, F J; Irastorza, I G; Jacoby, J; Jakobsen, A; Jakov?i?, K; Kaminski, J; Karuza, M; Kavuk, M; Kr?mar, M; Krieger, C; Krüger, A; Laki?, B; Laurent, J M; Liolios, A; Ljubi?i?, A; Luzón, G; Neff, S; Ortega, I; Papaevangelou, T; Pivovarov, M J; Raffelt, G; Riege, H; Rosu, M; Ruz, J; Savvidis, I; Solanki, S K; Vafeiadis, T; Villar, J A; Vogel, J K; Yildiz, S C; Zioutas, K; Brax, P; Lavrentyev, I; Upadhye, A

    2015-01-01

    In this work we present a search for (solar) chameleons with the CERN Axion Solar Telescope (CAST). This novel experimental technique, in the field of dark energy research, exploits both the chameleon coupling to matter ($\\beta_{\\rm m}$) and to photons ($\\beta_{\\gamma}$) via the Primakoff effect. By reducing the X-ray detection energy threshold used for axions from 1$\\,$keV to 400$\\,$eV CAST became sensitive to the converted solar chameleon spectrum which peaks around 600$\\,$eV. Even though we have not observed any excess above background, we can provide a 95% C.L. limit for the coupling strength of chameleons to photons of $\\beta_{\\gamma}\\!\\lesssim\\!10^{11}$ for $1<\\beta_{\\rm m}<10^6$.

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

    Directory of Open Access Journals (Sweden)

    Xiao Xiaofeng

    2012-05-01

    Full Text Available 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 microscope, SEM, EDX and XRD. Micrographs indicate that the boundary of bimetal combination regions is staggered like dogtooth, two liquid metals are not mixed, and the interface presents excellent metallurgical bonding state. After heat treatment, the composite liner specimens have shown excellent properties, including hardness > 61 HRC, fracture toughness ?k >16.5 J·cm-2 and bending strength >1,600 MPa. Wear comparison was made between the bimetal composite liner and alloyed steel liner in an industrial hematite ball mill of WISCO, and the results of eight-month test in wet grinding environment have proved that the service life of the bimetal composite liner is three times as long as that of the alloyed steel liner.

  16. Impact Strength of Austenitic and Ferritic-Austenitic Cr-Ni Stainless Cast Steel in -40 and +20°C Temperature

    Directory of Open Access Journals (Sweden)

    Kalandyk B.

    2014-10-01

    Full Text Available Studies described in this paper relate to common grades of cast corrosion resistant Cr-Ni steel with different matrix. The test materials were subjected to heat treatment, which consisted in the solution annealing at 1060°C followed by cooling in water. The conducted investigations, besides the microstructural characteristics of selected cast steel grades, included the evaluation of hardness, toughness (at a temperature of -40 and +20oC and type of fracture obtained after breaking the specimens on a Charpy impact testing machine. Based on the results of the measured volume fraction of ferrite, it has been found that the content of this phase in cast austenitic steel is 1.9%, while in the two-phase ferritic-austenitic grades it ranges from 50 to 58%. It has been demonstrated that within the scope of conducted studies, the cast steel of an austenitic structure is characterised by higher impact strength than the two-phase ferritic-austenitic (F-A grade. The changing appearance of the fractures of the specimens reflected the impact strength values obtained in the tested materials. Fractures of the cast austenitic Cr-Ni steel obtained in these studies were of a ductile character, while fractures of the cast ferritic-austenitic grade were mostly of a mixed character with the predominance of brittle phase and well visible cleavage planes.

  17. Computer precision simulation for titanium casting centrifugal mold filling of prescision titanium castings

    Directory of Open Access Journals (Sweden)

    Daming XU

    2004-08-01

    Full Text Available Computer simulation codes were developed based on proposed mathematical model for centrifugal mold filling processes and previous computer software for 3D mold filling and solidification of castings. Sample simulations were implemented for mold filling processes of precision titanium castings under gravity and different centrifugal casting techniques. The computation results show that the alloy melt has a much stronger mold filling ability for thin section castings unde a centrifugal force field than that only under the gravity. A "return back" mold filling manner is showed to be a reasonable technique for centrifugal casting processes, especially for thin section prcision castings.

  18. Microtensile strain on the corrosion performance of diamond-like carbon coating.

    Science.gov (United States)

    Lee, Seung-Hwan; Kim, Jung-Gu; Choi, Heon-Woong; Lee, Kwang-Ryeol

    2008-06-01

    Hydrogenated diamond-like carbon films (a-C:H DLC) were deposited on STS 304 substrates for the fabrication of vascular stents by means of the r.f. plasma-assisted chemical vapor deposition technique. This study provides reliable and quantitative data for the assessment of the effect of strain on the corrosion performance of DLC-coated systems in the simulated body fluid obtained through electrochemical techniques (potentiodynamic polarization test and electrochemical impedance spectroscopy) and surface analysis (scanning electron microscopy). The electrolyte used in this test was 0.89% NaCl solution at pH 7.4 and 37 degrees C. It was found that the corrosion resistance of the plastically deformed DLC coating was insufficient for use as a protective film in a corrosive body environment. This is due to the increase in the delamination area and degradation of the substrate's corrosion properties with increasing tensile deformation. PMID:17896779

  19. Rubber molds for investment casting

    International Nuclear Information System (INIS)

    The main objective of the project is to investigate different types of molding rubbers used for investment casting. The level of shape complexity which can be achieved by using these rubber molds is also studied. It was almost impossible to make complex shapes molds using metal molds, in that cases rubber molds are very important because they arc flexible and give accurate and precise part dimensions. Turbine blades are hi-tech components with air-foil geometries that have close dimensional tolerances. They are made of super-alloys and manufactured by investment casting. The final blade profile depends upon the dimensional accuracy in each of the processing steps. In the present work experimental study for the production of high quality low cost castings of turbine blades using rubber molds and injected wax patterns is presented. Natural Rubber molds and wax patterns from these molds were made. Different types of molding rubbers were studied including natural rubber, silicone rubber and liquid silicone rubber. It was found that by using rubber molds we can make most complex shape with very less finishing required. The shrinkage was 12% as compared to original master pattern. Rubber molds were made using laboratory hot press. Three layers of rubber above and below the master pattern. After that vulcanization was done by giving temperature and pressure. (author)

  20. Structure and Corrosion Resistance of Ca50Mg20Cu30 Bulk Metallic Glasses

    Science.gov (United States)

    Babilas, Rafa?; Cesarz-Andraczke, Katarzyna; Babilas, Dorota; Simka, Wojciech

    2015-01-01

    The ternary Ca50Mg20Cu30 bulk metallic glass with thickness of 1 mm and width of 10 mm was successfully fabricated by conventional copper-mold casting method. The structural characterization of the alloy in the "as-cast" and after-annealing states was carried out using x-ray diffraction method. The corrosion behaviors of the glassy and crystalline samples were studied by electrochemical measurements and immersion tests in a 5% NaCl solution at room temperature. The amorphous alloy showed higher corrosion resistance than crystalline samples. The post-test analyses were conducted by scanning electron microscopy and energy-dispersive x-ray spectroscopy to examine the damage and chemical composition of the investigated surfaces.

  1. Oxidation and hot corrosion of coated and bare oxide dispersion strengthened superalloy MA-755E

    Science.gov (United States)

    Glasgow, T. K.; Santoro, G. J.

    1981-01-01

    Cyclic hot corrosion and oxidation of an experimental oxide dispersion strengthened (ODS) superalloy MA-755E were conducted in a hot gas stream at Mach 0.3. The response of the ODS alloy, bare or with protective coatings, was similar to that of a conventional cast alloy, IN-792, in hot corrosion at 900 C. However, during oxidation at 1100 and 1150 C the ODS alloy differed from the cast alloy by developing a greater amount of subsurface porosity. Compared with a diffused aluminide coating, an electron beam vapor deposited NiCrAlY coating offered superior oxidation protection and decreased porosity formation. In additional testing, the tendency to form porosity was associated with the large grains of recrystallized powder metallurgy alloys but was independent of the presence of an oxide dispersion.

  2. Calcificación vascular: tipos y mecanismos / Vascular calcification: types and mechanisms

    Scientific Electronic Library Online (English)

    J.M., Valdivielso.

    Full Text Available Clásicamente se consideraba que la calcificación vascular era un proceso pasivo y degenerativo que frecuentemente ocurría con la edad avanzada, aterosclerosis, varias alteraciones metabólicas (como diabetes mellitus y estados finales de enfermedad renal) y en raras enfermedades genéticas. Sin embarg [...] o, desde hace algunos años, la calcificación vascular es considerada como un proceso activo y regulado de manera semejante a la mineralización y metabolismo del hueso, en el se encuentran implicadas diversas proteínas óseas. Resultados recientes cuestionan la clásica separación de la calcificación vascular en calcificación de la íntima y calcificación de la media, al menos en arterias de capacitancia. Mecanismos procalcificantes y anticalcificantes desempeñan un papel activo en la deposición de calcio en las células vasculares, por lo que su estudio se ha convertido en un área muy activa de investigación. La identificación de dianas terapéuticas que puedan enlentecer o incluso revertir la calcificación vascular podría suponer un avance muy importante en las estrategias terapéuticas para los pacientes afectados de enfermedades renales. Abstract in english Vascular calcification has traditionally been considered to be a passive process that was associated with advanced age, atherosclerosis, uncommon genetic diseases and some metabolic alterations such as diabetes mellitus and end-stage kidney failure. However, in the last years, vascular calcification [...] has been proven to be an active and regulated process, similar to bone mineralisation, in which different bone-related proteins are involved. Recent results question the classic classification of vascular calcification into intimal and medial calcification, at least in capacitance arteries. Pro and anti-calcifying mechanisms play an active role in calcium deposition in vascular cells, making this area an active focus of research. The identification of therapeutic targets which can slow down the progression or even reverse vascular calcification could be an important step forward in the treatment of patients with chronic kidney disease.

  3. 40 CFR 464.30 - Applicability; description of the ferrous casting subcategory.

    Science.gov (United States)

    2010-07-01

    ...Applicability; description of the ferrous casting subcategory. 464...GUIDELINES AND STANDARDS METAL MOLDING AND CASTING POINT SOURCE CATEGORY Ferrous Casting Subcategory § 464...Applicability; description of the ferrous casting...

  4. Non-Magnetic, Tough, Corrosion- and Wear-Resistant Knives From Bulk Metallic Glasses and Composites

    Science.gov (United States)

    Hoffman, Douglas C.; Potter, Benjamin

    2013-01-01

    Quality knives are typically fabricated from high-strength steel alloys. Depending on the application, there are different requirements for mechanical and physical properties that cause problems for steel alloys. For example, diver's knives are generally used in salt water, which causes rust in steel knives. Titanium diver's knives are a popular alternative due to their salt water corrosion resistance, but are too soft to maintain a sharp cutting edge. Steel knives are also magnetic, which is undesirable for military applications where the knives are used as a tactical tool for diffusing magnetic mines. Steel is also significantly denser than titanium (8 g/cu cm vs. 4.5 g/cu cm), which results in heavier knives for the same size. Steel is hard and wear-resistant, compared with titanium, and can keep a sharp edge during service. A major drawback of both steel and titanium knives is that they must be ground or machined into the final knife shape from a billet. Since most knives have a mirrored surface and a complex shape, manufacturing them is complex. It would be more desirable if the knife could be cast into a net or near-net shape in a single step. The solution to the deficiencies of titanium, steel, and ceramic knives is to fabricate them using bulk metallic glasses (or composites). These alloys can be cast into net or near-net shaped knives with a combination of properties that exceed both titanium and steel. A commercially viable BMG (bulk metallic glass) or composite knife is one that exhibits one or all of the following properties: It is based on titanium, has a self-sharpening edge, can retain an edge during service, is hard, is non-magnetic, is corrosion-resistant against a variety of corrosive environments, is tough (to allow for prying), can be cast into a net-shape with a mirror finish and a complex shape, has excellent wear resistance, and is low-density. These properties can be achieved in BMG and composites through alloy chemistry and processing. For each desired property for knife fabrication and performance, there is an alloy development strategy that optimizes behavior. Although BMG knives have been demonstrated as far back as 1995, they never found commercial success because they had to be ground (which presented problems because the alloys contained beryllium), they weren't low cost (because they weren't cast to a net-shape), they were brittle (because they were made with a low-quality commercial material), and they had extremely poor corrosion resistance (because corrosion was not well-understood in these materials). Ultimately, these shortcomings prevented the widespread commercialization. In the current work, the inventors have applied more than a decade of research on BMGs from Caltech and JPL to develop a better understanding of how to make BMG knives that exhibit an optimal combination of properties, processing and cost. Alloys have been developed based in titanium (and other metals), that exhibit high toughness, high hardness, excellent corrosion resistance, no ferromagnetism, edge-retaining selfsharpening, and the ability to be cast like a plastic using commercially available casting techniques (currently used by commercial companies such as Liquidmetal Technologies and Visser Precision Casting). The inventors argue that depending on the application (diving, military, tactical, utility, etc.) there is an optimal combination of design and alloy composition. Moreover, with new casting technologies not available at the inception of these materials, net-shaped knives can be cast into complex shapes that require no aftermarket forming, except for sharpening using water-cooled polishing wheel. These combinations of discoveries seek to make low-cost BMG knives commercially viable products that have no equal among metal or ceramic knives. Current work at JPL focuses on net-shape casting of these alloys and testing their mechanical properties versus commercially available knives to demonstrate their benefits.

  5. Vascular remodeling in pulmonary hypertension

    OpenAIRE

    Chang, Ya-Ting

    2015-01-01

    Pulmonary hypertension (PH) is a progressive obliterative vasculopathy with multifactorial etiology and high mortality rate. Endothelial dysfunction, excessive vascular remodeling, inflammation and in situ thrombosis contribute to increased vascular resistance and gradual occlusion of pulmonary vessels. Sustained high pressure in the pulmonary circulation increases right heart afterload and ultimately results in right heart failure. Current pharmacological treatments, like endothelin receptor...

  6. Corrosion resistance 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 is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast iron insert fitted inside a copper canister. SKB has since several years developed manufacturing processes for the canister components using a network of manufacturers. For the encapsulation process SKB has built the Canister Laboratory to demonstrate and develop the encapsulation technique in full scale. The critical part of the encapsulation of spent fuel is the sealing of the canister which is done by welding the copper lid to the cylindrical part of the canister. Two welding techniques have been developed in parallel, Electron Beam Welding (EBW) and Friction Stir Welding (FSW). During the past two decades, SKB has developed the technology EBW at The Welding Institute (TWI) in Cambridge, UK. The development work at the Canister Laboratory began in 1999. In electron beam welding, a gun is used to generate the electron beam which is aimed at the joint. The beam heats up the material to the melting point allowing a fusion weld to be formed. The gun was developed by TWI and has a unique design for use at reduced pressure. The system has gone through a number of improvements under the last couple of years including implementation of a beam oscillation system. However, 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 at the new grain boundaries that might pose adverse effects on the corrosion resistance of welds. As a new method for joining, SKB has been developing friction stir welding (FSW) for sealing copper canisters for spent nuclear fuel in cooperation with TWI since 1997. FSW was invented in 1991 at TWI and is a thermo mechanical solid-state process, i.e. not a fusion welding method. The FSW tool consists of two parts: a tapered pin (or probe) and a shoulder. The function of the tool is to heat up the material by means of friction and, by virtue of its shape, force the material to flow around it and create a joint. This means that the problems encountered in fusion welding, for example unfavourable grain structure and size and segregation phenomena, can be avoided. The microstructure in copper resulting from FSW resembles the microstructure resulting from hot forming of the copper components in the canister. However, some impurities from the tool, such as metal particles, have been detected in the weld material. This study aimed to investigate whether the driving force of galvanic corrosion between weld material and base material could pose a problem and whether metallic particles originating from the FSW tool could induce and sustain corrosion. In this study, a surface untreated FSW tool was used to simulate the worst case scenario. For today's FSW welds, the tools have been surface treated which results in no detectable levels of metal particles in the weld. For the study described in this report, 9 samples from FSW (produced with surface untreated tools) and 1 EBW sample were investigated in this study. As result, the FSW samples show less corrosion compared to EBW and the residues from FSW tool do not influence corrosion adversely. Furthermore, copper oxides do not influence the corrosion properties of FSW welds noticeably. In conclusion, FSW for sealing copper canisters for spend nuclear fuel provides more durable welds from a corrosion point of view

  7. Corrosion Resistance of Mo3Si with Niobium Additions in Hydrochloric Acid

    OpenAIRE

    Huicochea, C.; Rosales, I.; Castan?eda, I. E.; Uruchurtu, J.

    2007-01-01

    In the present work, the electrochemical behavior of molybdenum-silica-niobium alloy produced by arc cast technique is presented, keeping silica constant (at 24 wt %), using different niobium concentrations (5, 10, 15 & 20 wt %) as alloying elements. These samples were immersed in an electrochemical solution of 10 % by volume hydrochloric acid. The corrosion behavior was obtained using electrochemical techniques, namely: open circuit potential, polarization curves and electrochemical current ...

  8. Development of a iron pipe corrosion simulation model for a water supply network

    OpenAIRE

    M. Bernats; S. W. Osterhus; K. Dzelzitis; Juhna, T.

    2012-01-01

    Corrosion in water supply networks is unwanted process that causes pipe material loss and subsequent pipe failures. Nowadays pipe replacing strategy most often is based on pipe age, which is not always the most important factor in pipe burst rate. In this study a methodology for developing a mathematical model to predict the decrease of pipe thickness in a large cast iron networks is presented. The quality of water, the temperature and the water flow regime were the main factors taken into ac...

  9. Coxiella burnetii vascular graft infection

    Directory of Open Access Journals (Sweden)

    Von Segesser Ludwig

    2005-12-01

    Full Text Available Abstract Background Coxiella burnetii, the causative agent of Q fever, may cause culture-negative vascular graft infections. Very few cases of C. burnetii infection of a vascular graft have been reported. All were diagnosed by serology. Case presentation We report the first case of Coxiella burnetii vascular graft infection diagnosed by broad-range PCR and discuss the diagnostic approaches and treatment strategies of chronic C. burnetii infection. Conclusion C. burnetii should be considered as etiological agent in patients with a vascular graft and fever, abdominal pain, and laboratory signs of inflammation, with or without exposure history. Broad-range PCR should be performed on culture-negative surgical samples in patients with suspected infection of vascular graft.

  10. Anti Corrosive Rubber Coating

    Directory of Open Access Journals (Sweden)

    Atul J. Shah

    2013-05-01

    Full Text Available The main objective of this review is to describe some of the important topics related to the use of marine and protective coatings for anti-corrosive purposes.In this context,” protective” refers to coatings for containers, off shore construction, pipe lines, pumps, steel structures, chemical equipment, bridged, storage tanks and petrochemical plants. The review aims at providing a thorough picture of state-of-the-art in anti-corrosivecoatings systems. International and national legislation aiming at reducing the emission of volatile organic compounds (VOCs have caused significant changes in the anti-corrosive coating industries. An important aspect in the development of new VOC –compliant, high performance anti-corrosive coating system is a thorough knowledge of the components in anti-corrosive coatings, their interaction, their advantages and limitations as well as detailed knowledge on the failure modes of anticorrosive coatings. The different types of anticorrosive coatings are presented, and the most widely applied generic types of binders and pigments in anticorrosive coatings

  11. COPPER CORROSION RESEARCH UPDATE

    Science.gov (United States)

    Copper release and corrosion related issues continue to be important to many water systems. The objective of this presentation is to discuss the current state of copper research at the USEPA. Specifically, the role of aging on copper release, use of phosphates for copper corrosio...

  12. Corrosion inhibitor compositions

    International Nuclear Information System (INIS)

    A corrosion inhibitor compositon for hydrocarbon fuels consisting essentially of, by weight, (A) about 75% to 95% of at least one polymerized unsaturated aliphatic monocarboxylic acid, said unsaturated acid having 16 to 18 carbons per molecule, and (B) about 5% to 25% of at least one monoalkenylsuccinic acid in which the alkenyl group as 8 to 18 carbons

  13. Corrosion resistant cemented carbide

    International Nuclear Information System (INIS)

    This paper describes a corrosion resistant cemented carbide composite. It comprises: a granular tungsten carbide phase, a semi-continuous solid solution carbide phase extending closely adjacent at least a portion of the grains of tungsten carbide for enhancing corrosion resistance, and a substantially continuous metal binder phase. The cemented carbide composite consisting essentially of an effective amount of an anti-corrosion additive, from about 4 to about 16 percent by weight metal binder phase, and with the remaining portion being from about 84 to about 96 percent by weight metal carbide wherein the metal carbide consists essentially of from about 4 to about 30 percent by weight of a transition metal carbide or mixtures thereof selected from Group IVB and of the Periodic Table of Elements and from about 70 to about 96 percent tungsten carbide. The metal binder phase consists essentially of nickel and from about 10 to about 25 percent by weight chromium, the effective amount of an anti-corrosion additive being selected from the group consisting essentially of copper, silver, tine and combinations thereof

  14. [The cast structure after vacuum-pressure casting and centrifugal casting].

    Science.gov (United States)

    Finger, W; Jung, T; Quast, U

    1975-02-01

    Evaluation of polished sections revealed the following: 1. Grain size in marginal areas of the crown is, in general, smaller than it is in the occlusal region. 2. Grain size varies depending on the casting method applied. Differences in hardness were found only to a limited extent. They were not always in line with the grain structure. This phenomenon deviating from the rule cannot satisfactorily be explained. The piping distribution was in accordance with observations made so far. PMID:1091455

  15. Integrins in vascular development

    Directory of Open Access Journals (Sweden)

    R.O. Hynes

    1999-05-01

    Full Text Available Many growth factors and their protein kinase receptors play a role in regulating vascular development. In addition, cell adhesion molecules, such as integrins and their ligands in the extracellular matrix, play important roles in the adhesion, migration, proliferation, survival and differentiation of the cells that form the vasculature. Some integrins are known to be regulated by angiogenic growth factors and studies with inhibitors of integrin functions and using strains of mice lacking specific integrins clearly implicate some of these molecules in vasculogenesis and angiogenesis. However, the data are incomplete and sometimes discordant and it is unclear how angiogenic growth factors and integrin-mediated adhesive events cooperate in the diverse cell biological processes involved in forming the vasculature. Consideration of the results suggests working hypotheses and raises questions for future research directions.

  16. Integrins in vascular development

    Scientific Electronic Library Online (English)

    R.O., Hynes; B.L., Bader; K., Hodivala-Dilke.

    1999-05-01

    Full Text Available Many growth factors and their protein kinase receptors play a role in regulating vascular development. In addition, cell adhesion molecules, such as integrins and their ligands in the extracellular matrix, play important roles in the adhesion, migration, proliferation, survival and differentiation o [...] f the cells that form the vasculature. Some integrins are known to be regulated by angiogenic growth factors and studies with inhibitors of integrin functions and using strains of mice lacking specific integrins clearly implicate some of these molecules in vasculogenesis and angiogenesis. However, the data are incomplete and sometimes discordant and it is unclear how angiogenic growth factors and integrin-mediated adhesive events cooperate in the diverse cell biological processes involved in forming the vasculature. Consideration of the results suggests working hypotheses and raises questions for future research directions.

  17. Microstructural evolution in a duplex cast steel after quench ageing process

    Directory of Open Access Journals (Sweden)

    Z. Stradomski

    2007-09-01

    Full Text Available Purpose: The effectiveness and usefulness of the quench ageing on the service properties of massive duplex cast steel was presented in this work. The mechanism of precipitation of a ?-Cu phase and its effect on the mechanical properties of the cast steel were investigated.Design/methodology/approach: The microscopic analysis of the cast steel was performed on a Zeiss Axiovert 25 optical microscope. The substructure of ferrite was examined on a JOEL JEM 3010 high-resolution transmission electron microscope. The analysis of chemical composition of selected micro-regions was carried out using a JEOL JSM 5400 scanning microscope equipped with an EDS microanalyzer. The verification of the metallographic examination results was done using the Thermo-Calc program.Findings: The formation of the ?-Cu phase during quench ageing causes an increase in hardness and drop in impact resistance. The ageing parameters have a substantial influence on the ferrite substructure and the degree of coherence, dispersion and amount of the ?-Cu phase. The ageing treatment at 480°C causes the precipitation of the ?-Cu phase coherent with the matrix. This temperature of quench ageing produce also the formation of a ?’-Cr phase and an ?-Fe phase.Practical implications: Duplex cast steels are becoming an irreplaceable material in the elements of equipment exposed to the simultaneous action of corrosive and erosive environment. In the case of massive elements like pumps and pipeline elements, the effect of quench ageing is much lower which is associated with the presence of a large amount of the incoherent ?-Cu phase in the cast steel after the solution heat treatment.Originality/value: The lower temperature of quench ageing duplex cast steels with copper addition should not be lower than 500°C because of the temperature of an undesirable spinodal decomposition of the ferrite in 480°C which is partially responsible for the slight increase in hardness and a drastic drop in plastic properties.

  18. Gating of Permanent Molds for ALuminum Casting

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam; John F. Wallace; Tom Engle; Qingming Chang

    2004-03-30

    This report summarizes a two-year project, DE-FC07-01ID13983 that concerns the gating of aluminum castings in permanent molds. The main goal of the project is to improve the quality of aluminum castings produced in permanent molds. The approach taken was determine how the vertical type gating systems used for permanent mold castings can be designed to fill the mold cavity with a minimum of damage to the quality of the resulting casting. It is evident that somewhat different systems are preferred for different shapes and sizes of aluminum castings. The main problems caused by improper gating are entrained aluminum oxide films and entrapped gas. The project highlights the characteristic features of gating systems used in permanent mold aluminum foundries and recommends gating procedures designed to avoid common defects. The study also provides direct evidence on the filling pattern and heat flow behavior in permanent mold castings.

  19. Method for casting thin metal objects

    Energy Technology Data Exchange (ETDEWEB)

    Pehrson, Brandon P; Moore, Alan F

    2015-04-14

    Provided herein are various embodiments of systems for casting thin metal plates and sheets. Typical embodiments include layers of mold cavities that are oriented vertically for casting the metal plates. In some embodiments, the mold cavities include a beveled edge such that the plates that are cast have a beveled edge. In some embodiments, the mold cavities are filled with a molten metal through an open horizontal edge of the cavity. In some embodiments, the mold cavities are filled through one or more vertical feed orifices. Further disclosed are methods for forming a thin cast metal plate or sheet where the thickness of the cast part is in a range from 0.005 inches to 0.2 inches, and the surface area of the cast part is in a range from 16 square inches to 144 square inches.

  20. Structure of AlSi Skeleton Castings

    Directory of Open Access Journals (Sweden)

    M. Cholewa

    2012-04-01

    Full Text Available Skeleton castings macrostructure can be shaped in many ways, by choosing an appropriate material of cores and manufacturing technologies. Important factor, which puts foundry techniques over the other technologies of periodic cellular materials, is ability to adjust mechanical properties by changing the microstructure of an alloy from which the casting is made. The influence on the microstructure of the skeleton casting can be implemented by choosing the thermal properties, mainly thermal conductivity factor, of mould and core materials. Macro- and microstructure of skeleton castings with octahedron elementary cells was presented in this paper. The analysis concerns the differences in morphology of eutectic silicone depending on the location of measurements cross sections areas. The use of thermo-insulating material with appropriate properties assures correct fill of mould cavity and homogeneous microstructure on whole volume of skeleton casting. The selection of technological parameters of the casting process if very important as well.

  1. Mobile evaporator corrosion test results

    International Nuclear Information System (INIS)

    Laboratory corrosion tests were conducted on eight candidates to select a durable and cost-effective alloy for use in mobile evaporators to process radioactive waste solutions. Based on an extensive literature survey of corrosion data, three stainless steel alloys (304L, 316L, AL-6XN), four nickel-based alloys (825, 625, 690, G-30), and titanium were selected for testing. The corrosion tests included vapor phase, liquid junction (interface), liquid immersion, and crevice corrosion tests on plain and welded samples of candidate materials. Tests were conducted at 80 degrees C for 45 days in two different test solutions: a nitric acid solution. to simulate evaporator conditions during the processing of the cesium ion-exchange eluant and a highly alkaline sodium hydroxide solution to simulate the composition of Tank 241-AW-101 during evaporation. All of the alloys exhibited excellent corrosion resistance in the alkaline test solution. Corrosion rates were very low and localized corrosion was not observed. Results from the nitric acid tests showed that only 316L stainless steel did not meet our performance criteria. The 316L welded interface and crevice specimens had rates of 22.2 mpy and 21.8 mpy, respectively, which exceeds the maximum corrosion rate of 20 mpy. The other welded samples had about the same corrosion resistance as the plain samples. None of the welded samples showed preferential weld or heat-affected zone (HAZ) attack. Vapor corrosion was negligible for all alloys. All of the alloys except 316L exhibited either open-quotes satisfactoryclose quotes (2-20 mpy) or open-quotes excellentclose quotes (<2 mpy) corrosion resistance as defined by National Association of Corrosion Engineers. However, many of the alloys experienced intergranular corrosion in the nitric acid test solution, which could indicate a susceptibility to stress corrosion cracking (SCC) in this environment

  2. Influence of Technological Parameters of Furane Mixtures on Shrinkage Creation in Ductile Cast Iron Castings

    Directory of Open Access Journals (Sweden)

    Vasková I.

    2014-10-01

    Full Text Available Ductile cast iron (GS has noticed great development in last decades and its boom has no analogue in history humankind. Ductile iron has broaden the use of castings from cast iron into areas, which where exclusively domains for steel castings. Mainly by castings, which weight is very high, is the propensity to shrinkage creation even higher. Shrinkage creation influences mainly material, construction of casting, gating system and mould. Therefore, the main realized experiment was to ascertain the influence of technological parameters of furane mixture on shrinkage creation in castings from ductile iron. Together was poured 12 testing items in 3 moulds forto determine and compare the impact of various technological parameters forms the propensity for shrinkage in the casting of LGG.

  3. Mechanical properties of homogenized twin-roll cast and conventionally cast AZ31 magnesium alloys

    Directory of Open Access Journals (Sweden)

    Mariia Zimina

    2015-02-01

    Full Text Available The improvement of mechanical properties of magnesium alloys nowadays is very important, because of the variety of industrial applications. For this goal, the number of casting techniques and further treatments were developed. Among the continuous casting techniques, which allow producing long strips of the alloys, is twin-roll casting. Using this process one can get the magnesium alloy with finest microstructure and higher specific strength. In this paper the comparison of tensile properties of conventionally cast and twin-roll cast AZ31 magnesium alloys was made. Tensile tests were carried out with constant strain rate 10-3 s-1 at temperatures ranging from 100 to 300 °C. Both materials were tested in as-cast state and after homogenization treatment at 450 °C for 10 hours. The investigation showed that there are no significant changes in ductility of AZ31 conventionally cast alloy even after heat treatment, while the ductility of twin-roll cast alloy increases.

  4. Development and application of titanium alloy casting technology in China

    OpenAIRE

    Han, Hai; Xie, Cheng-mu; Zhao, Jia-qi

    2005-01-01

    The development and research of casting titanium alloy and its casting technology, especially its application in aeronautical industry in China are presented. The technology of moulding, melting and casting of titanium alloy, casting quality control are introduced. The existing problem and development trend in titanium alloy casting technology are also discussed.

  5. Borosilicate glass corrosion in the presence of steel corrosion products

    International Nuclear Information System (INIS)

    Since 1982, the corrosion behavior of radioactive high level waste glass and of inactive glasses of the same composition has been studied in the framework of a Japanese-Swedish-Swiss (JSS) project. In addition to granite and backfilling material, the influence of steel corrosion products on glass corrosion has been investigated in experiments of up to one year at 900C with a sample surface area to leachant volume ratio of 10 m-1. Leachant and steel corrosion products were separated from each other by filtration and analyzed by atomic absorption spectroscopy and ?-spectroscopy. The glass corrosion layers were characterized by optical and scanning electron microscopy and by secondary ion mass spectrometry. It could be shown, that glass corrosion is enhanced by steel corrosion products. The quantity of corroded glass seems to be dependent on the surface area and not on the total amount of steel corrosion products in the system, suggesting a mechanism controlled by silica sorption on the steel corrosion product. If lead oxide is added to the system, glass corrosion is almost totally suppressed. 9 references, 11 figures, 4 tables

  6. Automatic 3D vascular tree construction in CT angiography.

    Science.gov (United States)

    Chen, Zikuan; Molloi, Sabee

    2003-01-01

    This study presents an automatic method for 3D reconstruction of vascular trees using computed-tomography angiographic (CTA) images. The program starts with the CTA slices, performs a sequential procedure of 3D image formation, preprocessing, segmentation, thinning, skeleton pruning and tree construction. It ends with vascular trees along with quantitative data about the trees such as values of diameter, length and bifurcation angles. All the involved algorithms are presented with the emphasis given to the skeleton pruning and tree construction algorithms. The skeletons obtained using a 3D thinning algorithm may contain cycles, spurs, isolated sticks, and non-unit-width parts, which hinder tree construction. As a solution to this problem, a skeleton pruning and tree construction algorithm is proposed. At each stage of the automatic procedure, 3D rendering is provided for visual inspection of the computed results. In the final output, the constructed vascular trees are visualized by rendering the 3D trees and the 3D binary image together in a transparent display mode. The program is carried out in a fully automatic fashion, with a few default settings. Occasionally, user intervention is needed at the 3D segmentation stage to impose an appropriate threshold when the automatic 3D segmentation is obviously sub-optimal for vessel delineation. Experimental demonstrations on both coronary artery phantom and a cast of coronary artery tree of a swine animal model are provided. PMID:14575780

  7. Continuous casting of semisolid aluminium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Motegi, Tetsuichi; Tanabe, Fumi; Sugiura, Eiji [Chiba Inst. of Tech., Dept. of Metallurgical Engineering, Tsudanuma, Narashino (Japan)

    2002-07-01

    In order to make up wrought Al-1.63mass%Si-0.54mass%Mg alloy billets for thixoforming and thixocasting, semisolid continuous casting was carried out. An inclined cooling plate was used to make numerous {alpha} aluminium crystal seeds which dispersed in the molten alloy before casting. Seeds of primary {alpha} aluminium crystals in the molten alloy grew in the tundish prior to entering the mould of the casting machine. (orig.)

  8. Theory of uniqueness of Indian Caste System

    OpenAIRE

    Ashwin Kumar

    2005-01-01

    Classical studies on pre-modern Indian social structure have suggested apparent differences between the Indian caste system and social stratification as one can discern in other parts of the world. However, one needs to question such dogmatic assertions that such vast differences really existed. An endeavor is made in this research paper to reflect on the nature of caste hierarchy in pre-modern India. The caste system forms the significant basis of pre-modern Indian social structure. Early wr...

  9. Directional Solidification of Nodular Cast Iron

    Science.gov (United States)

    Curreri, P. A.; Stefanescu, D. M.; Hendrix, J. C.

    1987-01-01

    Cerium enhances formation of graphite nodules. Preliminary experiments in directional solidification of cast iron shows quantitative correlation of graphite microstructure with growth rate and thermal gradient, with sufficient spheroidizing element to form spheroidal graphite under proper thermal conditions. Experimental approach enables use of directional solidification to study solidification of spheriodal-graphite cast iron in low gravity. Possible to form new structural materials from nodular cast iron.

  10. Creep-resistant austenitic cast steel

    OpenAIRE

    B. Piekarski; J. Kubicki

    2008-01-01

    The study reviews the reference literature and gives some results of own investigations concerning changes of phase composition that take place in creep-resistant austenitic cast steel of two generations due to an ageing treatment. The cast steel of the first generation contains in its chemical composition only the alloying additives like nickel, chromium and silicon. Compared with the first group, the chemical composition of the second generation cast steel has been enriched with additions o...

  11. New progresses of Chinese art casting

    OpenAIRE

    Tan Derui

    2007-01-01

    The Chinese art casting with 5 000 years history has been rapidly developed in recent ten years. This benefits from the great development of Chinese economy, the large-scale urban construction and transformation, the increasing demands for the cultural work of art, the loose religious environment and the expanding international market. The Art Casting Technical Committee of China Foundry Association has been established for 10 years. Almost 90 art casting enterprises joined in the organizatio...

  12. Model castings with composite surface layer - application

    OpenAIRE

    J. Szajnar; P. Wróbel; T. Wróbel

    2008-01-01

    The paper presents a method of usable properties of surface layers improvement of cast carbon steel 200–450, by put directly in foundingprocess a composite surface layer on the basis of Fe-Cr-C alloy. Technology of composite surface layer guarantee mainly increase inhardness and aberasive wear resistance of cast steel castings on machine elements. This technology can be competition for generallyapplied welding technology (surfacing by welding and thermal spraying). In range of studies was m...

  13. Thermal gradient analysis of solidifying casting

    OpenAIRE

    J. Sucho?; M. Cholewa; M. Kondracki

    2008-01-01

    For description of casting solidification and crystallization process the thermal derivative analysis (TDA) is commonly used. Besides the process kinetics considered in TDA method to describe the solidification process, the thermal gradient analysis can be also used for this purpose [1, 2]. In conducted studies analysis of thermal gradient distribution inside the solidifying wedge casting was shown which enabled determination of heat flow intensity on casting section.

  14. Structure of AlSi Skeleton Castings

    OpenAIRE

    Cholewa, M.; Szuter, T.

    2012-01-01

    Skeleton castings macrostructure can be shaped in many ways, by choosing an appropriate material of cores and manufacturing technologies. Important factor, which puts foundry techniques over the other technologies of periodic cellular materials, is ability to adjust mechanical properties by changing the microstructure of an alloy from which the casting is made. The influence on the microstructure of the skeleton casting can be implemented by choosing the thermal properties, mainly thermal con...

  15. Thermal gradient analysis of solidifying casting

    Directory of Open Access Journals (Sweden)

    J. Sucho?

    2008-08-01

    Full Text Available For description of casting solidification and crystallization process the thermal derivative analysis (TDA is commonly used. Besides the process kinetics considered in TDA method to describe the solidification process, the thermal gradient analysis can be also used for this purpose [1, 2]. In conducted studies analysis of thermal gradient distribution inside the solidifying wedge casting was shown which enabled determination of heat flow intensity on casting section.

  16. Optimization of Castings by using Surrogate Models

    OpenAIRE

    Gustafsson, Erik

    2007-01-01

    In this thesis structural optimization of castings and thermomechanical analysis of castings are studied. In paper I an optimization algorithm is created by using Matlab. The algorithm is linked to the commercial FE solver Abaqus by using Python script. The optimization algorithm uses the successive response surfaces methodology (SRSM) to create global response surfaces. It is shown that including residual stresses in structural optimization of castings yields an optimal shape that differs si...

  17. Microsegregation in Nodular Cast Iron with Carbides

    OpenAIRE

    Pietrowski, S.; Gumienny, G.

    2012-01-01

    In this paper results of microsegregation in the newly developed nodular cast iron with carbides are presented. To investigate the pearlitic and bainitic cast iron with carbides obtained by Inmold method were chosen. The distribution of linear elements on the eutectic cell radius was examined. To investigate the microsegregation pearlitic and bainitic cast iron with carbides obtained by Inmold method were chosen.The linear distribution of elements on the eutectic cell radius was examined. Tes...

  18. Hot corrosion behaviour of a laser beam irradiated nickel base superalloy

    International Nuclear Information System (INIS)

    The structure and the hot corrosion resistance of cast nickel-base superalloy M 38 irradiated by CO2 laser beam of 1.3 KW output have been examined by means of optical microscopy, XRD, SEM and EPMA in comparison with un-irradiated specimens. The hot corrosion tests were carried out in a crucible filled with a mixture of 75 Na2SO4+25 NaCl at 9000C for 15, 35, 55, 80 and 100 hrs, respectively. The results showed that the corrosion resistance of the irradiated alloy is by a factor 2-3 higher than that of the cast alloy. In contrast to significant internal oxidation/sulfidation along the grain boundaries in the cast alloy, under a dense protective oxide scale mainly consisting of Cr2O3, there was not sign of internal oxidation/sulfidation in the irradiated alloy. The irradiated surface layer may be regarded as an effective barrier forming part of the superalloy itself. (orig.)

  19. Corrosion resistant zirconium alloys prepared by powder metallurgy

    International Nuclear Information System (INIS)

    Pure zirconium and zirconium 2.5% niobium were prepared by powder metallurgy. The powders were prepared directly from sponge and consolidated by cold isostatic pressing and sintering. Hot isostatic pressing was also used to obtain full density after sintering. For pure zirconium the effects of particle size, compaction pressure, sintering temperature and purity were investigated. Fully densified zirconium and Zr-2.5%Nb exhibited tensile properties comparable to cast material at room temperature and 3000F (1490C). Pressed and sintered material having density of 94-99% had slightly lower tensile properties. Corrosion tests were performed in boiling 65% H/sub 2/SO/sub 4/, 70% HNO/sub 3/, 20% HCl and 20% HCl + 500 ppm FeCl/sub 3/ (a known pitting solution). For fully dense material the observed corrosion behavior was nearly equivalent to cast material. A slightly higher rate of attack was observed for samples which were only 94-99% dense. Welding tests were also performed on zirconium and Zr-2.5%Nb alloy. Unlike P/M titanium alloys, these materials had good weldability due to the lower content of volatile impurities in the powder. A slight amount of weld porosity was observed but joint efficiencies were always not 100%, even for 94-99% density samples. Several practical applications of the P/M processed material will be briefly described

  20. Computer precision simulation for titanium casting centrifugal mold filling of prescision titanium castings

    OpenAIRE

    Xu, Daming; Li, Xin; An, Geving

    2004-01-01

    Computer simulation codes were developed based on proposed mathematical model for centrifugal mold filling processes and previous computer software for 3D mold filling and solidification of castings. Sample simulations were implemented for mold filling processes of precision titanium castings under gravity and different centrifugal casting techniques. The computation results show that the alloy melt has a much stronger mold filling ability for thin section castings unde a centrifugal force fi...

  1. Microstructures and formation mechanism of hypoeutectic white cast iron by isothermal electromagnetic rheocast process

    Directory of Open Access Journals (Sweden)

    Zhang Wanning

    2010-05-01

    Full Text Available An investigation was made on the evolution of microstructures of hypoeutectic white cast iron slurry containing 2.5wt.%C and 1.8wt.%Si produced by rheocasting in which the solidifying alloy was vigorously agitated by electromagnetic stirrer during isothermal cooling processes. The results indicated that under the proper agitating temperatures and speeds applied, the dendrite structures in white cast iron slurry were gradually evolved into spherical structures during a certain agitating time. It also revealed that the bent dendrites were formed by either convection force or by the growth of the dendrites themselves in the bending direction; then, as they were in solidifying, they were gradually being alternated into separated particles and into more spherical structures at the end of the isothermal cooling process. Especially, the dendrites were granulated as the bending process proceeding, which suggested that they were caused by unwanted elements such as sulfur and phosphor usually contained in engineering cast iron. Convective flow of the melt caused corrosion on the dendritic segments where they were weaker in strength and lower in melting temperature because of higher concentration of sulfur or phosphor. And the granulation process for such dendrites formed in the melt became possible under the condition. Certainly, dendrite fragments are another factors considerable to function for spherical particles formation. A new mechanism, regarding to the rheocast structure formation of white cast iron, was suggested based on the structural evolution observed in the study.

  2. The Effect of Electromagnetic Stirring on the Microstructural and Mechanical Properties of A356 Casting Alloy

    Directory of Open Access Journals (Sweden)

    Murat ÇOLAK

    2009-03-01

    Full Text Available Aluminium casting alloys, having high strength, high corrosion resistance, high thermal conductivity and low density, are widely used in automotive and many other industrial areas. However, to meet new demands from the industry for superior properties the conventional cast aluminium alloys still need further improvements. In recent years, the desire of new processes to improve the properties of aluminium casting alloys resulted in new researches into high performance and low cost processes such as semi solid forming. Semi-solid forming processes are widely used for Al-Si casting alloys having large eutectic proportions, high fluidity and good castability such as the A356 alloy. In this process the morphology of the primary alpha phase and the formation of thixotropic material structure play an important role. There are several techniques for producing thixotropic materials through degenerating the dendrites and the most effective of them is electromagnetic stirring. In this study, the effect of electromagnetic stirring on the microstructural and mechanical properties during solidification of A356 alloy which has been produced with electromagnetic stirring has been investigated.

  3. The effect of casting porosities on cavitational erosion of intermetallic alloy FeAl36

    Directory of Open Access Journals (Sweden)

    R. Jasionowski

    2010-07-01

    Full Text Available The machinery and equipment elements operating in a turbulent fluid flow, are exposed to destruction as a result of the impact of thecavitation, corrosion and abrasion processes, among which are hardest to minimize the imploding cavitation bubbles. Repeated cavitationimplosions of bubbles give rise to cracks, material loss, resulting in increased flow resistance and reduction of the efficiency of the device, or even its destruction. In order to prevent or mitigate the cavitation phenomenon and its harmful effects, two basic methods are applied. The first of these is the selection of geometrical parameters and hydraulic machinery and the relevant elements of the streamlined shape and flow channels. The second solution is the selection of engineering plastics with greater resistance to cavitation. In case of materials manufactured with the casting method, a very important role is being played by the quality of manufactured casting having the smallest number of casting defects. The aim of the present study was to examine the effect of casting porosities of an intermetallic alloy FeAl36 on cavitational erosion.

  4. Tape casting of proton conducting ceramic material

    OpenAIRE

    Costa, Re?mi; Hafsaoui, Julien; Almeida Oliveira, Ana Paula; Grosjean, Arnaud; Caruel, Matthieu; Chesnaud, Anthony; Thorel, Alain

    2009-01-01

    This work explores experimental procedures for tape-cast proton conducting ceramic fuel cells (PCFC) based on Yttrium-doped Barium Cerate (BCY10). The work is based on several years experience on aqueous tape-casting applied to the shaping of YSZ-based SOFC: however, water-based tape casting of BCY10 appeared to be impracticable for reasons associated with the high basicity of this material that results in rapid hydrolysis when in contact with water. Organic tape casting was therefore develop...

  5. Microstructured metal molds fabricated via investment casting

    International Nuclear Information System (INIS)

    This paper describes an investment casting process to produce aluminum molds having integrated microstructures. Unlike conventional micromolding tools, the aluminum mold was large and had complex curved surfaces. The aluminum was cast from curved microstructured ceramic molds which were themselves cast from curved microstructured rubber. The aluminum microstructures had an aspect ratio of 1:1 and sizes ranging from 25 to 50 µm. Many structures were successfully cast into the aluminum with excellent replication fidelity, including circular, square and triangular holes. We demonstrate molding of large, curved surfaces having surface microstructures using the aluminum mold.

  6. REDUCING DEFECTS ON STONE CRUSHER CASTINGS

    Directory of Open Access Journals (Sweden)

    K. Subrahmanyam

    2014-04-01

    Full Text Available Metal casting involves pouring molten metal into a mould containing a cavity of the desired shape to produce a molten product. Foundry industry suffers from poor quality and productivity due to the large number of process parameters, combined with lower penetration of manufacturing automation and shortage of skilled workers compared to other industries. Global buyers demand defect-free castings and strict delivery schedule, which foundries are finding it very difficult to meet. The casting is then removed from the mould and excesses material is removed, often using shot blasting, grinding or welding processes. The product may then undergo a range of processes such as heat treatment, polishing and surface coating or finishing. Unfortunately, this is not an easy task, since casting process involves complex interactions among various parameters and operations For achieving the defect free casting, Design of Casting process is very necessary. By fallowing the sequence of designed steps, the designed casting will be prepared. In this work, we present a 3-step approach to casting defect identification, analysis and rectification. Casting the defects will be identified Visual inspection, MPI (magnetic particle inspection, U.T (ultrasonic testing, R.T (Radiographic testing, and Final inspection. By all these inspections defects need to be diagnosed such as correctly for appropriate remedial measures, otherwise new defects may be introduced. Some defects diagnosed as cracks, Undersurface cracks, External slag inclusions, shrinkages, gas generated defects. These defects will be analyzed and rectification processes fallowed, so finally defects will reduced.

  7. Aluminium Alloy Cast Shell Development for Torpedoes

    Directory of Open Access Journals (Sweden)

    Vijaya Singh

    2005-01-01

    Full Text Available The sand-cast aluminium alloy cylindrical shells were developed for the advanced experimental torpedo applications. The components had intricate geometry, thin-walled sections, and stringent property requirements. The casting defects, such as shrinkage, porosity, incomplete filling of thin sections, cold shuts, inclusions and dimensional eccentricity, etc were found inthe initial castings trials. improvements in casting quality were achieved through modified methodology, selective chilling, risering, and by introducing ceramic-foam filters in the gatingsystem. The heat-treated and machined components met radiographic class I grade C/E standards, mechanical properties to BS1490 specifications, and leakage and hydraulic pressure testrequirements relevant for such applications.

  8. Ductile iron castings fabricated using metallic moulds

    International Nuclear Information System (INIS)

    The features and suitability of high requirements ductile iron castings production using metallic moulds have been studied in the present work. The structural and mechanical properties of the produced castings have been analysed and compared to the corresponding ones but fabricated using green sand moulds according to a conventional production process. The higher cooling rate in the metallic moulds is the main cause for the appearance of the detected structural changes in castings. The mechanical and microstructural properties obtained directly on castings are remarkable due to the higher nodule count among other factors. Finally, the benefits and inconveniences found in this kind of production methodology using metallic moulds are also discussed. (Author)

  9. Friction Stir Processing of Cast Superalloys Project

    National Aeronautics and Space Administration — This SBIR effort examines the feasibility of an innovative fabrication technology incorporating sand casting and friction stir processing (FSP) for producing...

  10. Friction Stir Processing of Cast Superalloys Project

    National Aeronautics and Space Administration — This SBIR Phase I effort examines the feasibility of an innovative fabrication technology incorporating sand casting and friction stir processing (FSP) for...

  11. Cast functional accessories for heat treatment furnaces

    Directory of Open Access Journals (Sweden)

    A. Drotlew

    2010-10-01

    Full Text Available The study gives examples of the cast functional accessories operating in furnaces for the heat treatment of metals and alloys. The describeddesign solutions of castings and their respective assemblies are used for charge preparation and handling. They were put in systematicorder depending on furnace design and the technological purpose of heat treatment. Basic grades of austenitic cast steel, used for castings of this type, were enumerated, and examples of general guidelines formulated for their use were stated. The functional accessories described in this study were designed and made by the Foundry Research Laboratory of West Pomeranian University of Technology.

  12. Effects of secondary phase and grain size on the corrosion of biodegradable Mg-Zn-Ca alloys.

    Science.gov (United States)

    Lu, Y; Bradshaw, A R; Chiu, Y L; Jones, I P

    2015-03-01

    The bio-corrosion behaviour of Mg-3Zn-0.3Ca (wt.%) alloy in simulated body fluid (SBF) at 37°C has been investigated using immersion testing and electrochemical measurements. Heat treatment has been used to alter the grain size and secondary phase volume fraction; the effects of these on the bio-corrosion behaviour of the alloy were then determined. The as-cast sample has the highest bio-corrosion rate due to micro-galvanic corrosion between the eutectic product (Mg+Ca2Mg6Zn3) and the surrounding magnesium matrix. The bio-corrosion resistance of the alloy can be improved by heat treatment. The volume fraction of secondary phases and grain size are both key factors controlling the bio-corrosion rate of the alloy. The bio-corrosion rate increases with volume fraction of secondary phase. When this is lower than 0.8%, the dependence of bio-corrosion rate becomes noticeable: large grains corrode more quickly. PMID:25579949

  13. The temperature gradient on section of casting in process of primary crystallization of chromium cast iron

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2008-08-01

    Full Text Available The methodology of defining in article was introduced the temperature gradient in process of primary crystallization during cooling the casting from chromium cast iron on basis of measurements of thermal field in test DTA-K3. Insert also the preliminary results of investigations of influence temperature gradient on structure of studied wear resistance chromium cast iron.

  14. Material behaviour with superimposition of corrosion fatigue cracking and other specific manifestations of corrosion

    International Nuclear Information System (INIS)

    The dangers of corrosion fatigue cracking - the influencing factors which have the effect of reducing durability - a classification of possible damaging mechanisms occurring together with corrosion manifestations of corrosion, such as pitting and intergranular corrosion - damage analysis based on laboratory tests and cases of damage taken from actual practice: pitting and corrosion fatigue cracking, stress corrosion and corrosion fatigue cracking, cavitation, corrosion fatigue cracking and hydrogen embrittlement. (orig.)

  15. Laser surface treatment of cast Al-Si-Cu alloys

    Directory of Open Access Journals (Sweden)

    K. Labisz

    2013-12-01

    Full Text Available Purpose: The test results presented in this chapter concern formation of the quasi-composite MMCs structure on the surface of elements from aluminium cast alloys AC-AlSi9Cu and AC-AlSi9Cu4 by fusion of the carbide or ceramic particles WC, SiC, ZrO2 and Al2O3 in the surface of alloys. In addition, within the scope of the tests the phase transformations and precipitation processes present during laser remelting and fusion at appropriately selected parameters: laser power, the rate of fusion and quantity of the ceramic powder fed have been partially examined. Design/methodology/approach: In general, the laser surface processing should result in achievement of the surface layer with the most favourable physical and mechanical properties, in particular enhancement of surface hardness, improvement of abrasion resistance and resistance to corrosion is assumed in relation to the selected aluminium alloys after standard thermal processing. Findings: The presented results of the surface layer include analysis of the mechanisms responsible for formation of the layer, and particularly concern remelting of the substrate and its crystallisation at various parameters of the High Power Diode Laser (HPDL and the technological conditions of the surface processing, remelting and fusion of the particles in the surface of cast alloys ACAlSi9Cu and ACAlSi9Cu4. For the purpose of testing the structure of the obtained surface layers the test methods making use of the light microscopy method supported with computer image analysis, transmission and scanning electron microscopy, X-ray analysis, X-ray microanalysis, as well as methods for testing the mechanical and usable properties have been used. Practical implications: What is more, development of the technology of surface refinement of cast alloys Al-Si-Cu with the laser fusion methods will allow for complex solving of the problem related to enhancement of the surface layer properties, taking into account both economic and ecological aspects. Originality/value: On the basis of the test result analysis it has been pointed out that in case of the analysed aluminium cast alloys the applied laser surface processing, and the thermal processing preceding it, ensuring occurrence of the mechanisms responsible for material strengthening, enable enhancement of the mechanical and usable properties of the examined alloys. An essential objective is also to indicate the multiple possibilities for continuation of the tests, regarding the light metal alloys aluminium, magnesium and titanium, broadening the current knowledge within the scope of elements and light structures.

  16. Surface morphology, microstructure and properties of as-cast AZ31 magnesium alloy irradiated by high intensity pulsed ion beams

    Science.gov (United States)

    Ma, Xuesong; Zhang, Gang; Wang, Guotian; Zhu, Guoliang; Zhou, Wei; Wang, Jun; Sun, Baode

    2014-08-01

    High intensity pulsed ion beam (HIPIB) irradiation was performed as surface modification to improve the properties of as-cast AZ31 magnesium (Mg) alloys. The surface morphology and microstructure of the irradiated Mg alloys were characterized and their microhardness, wear resistance and corrosion resistance before and after HIPIB irradiation were measured. The results show that the formation of crater on the surface was attributed to the particles impacted from the irradiated cathode material. HIPIB irradiation resulted in more vacancy defects on the surface of the material. Moreover, new dislocations were generated by the reaction between vacancies, and the dislocation configuration was also changed. These variations caused by the HIPIB are beneficial for improving the material properties. After 10 shots of irradiation, the average microhardness increased by 27.1% but the wear rate decreased by 38.5%. The corrosion rate was reduced by 24.8% according to the salt spray corrosion experiment.

  17. Quench ageing behaviour of duplex cast steel with nano-scale ?-Cu particles

    Directory of Open Access Journals (Sweden)

    D. Dyja

    2007-01-01

    Full Text Available Purpose: The aim of the study was to examine the effectiveness and usefulness of the quench ageing on theservice properties of massive duplex cast steel. The mechanism of precipitation of a ?-Cu phase and its effect onthe mechanical properties of the cast steel were investigated.Design/methodology/approach: The ferrite substructure was examined on a JOEL JEM HREM. The analysisof chemical composition of selected micro-regions was carried out using a scanning electron microscope. Theverification of the metallographic examination results was done using the Thermo-Calc program.Findings: Quench ageing causes an increase in hardness and drop in impact resistance, which results from theformation of the ?-Cu phase. The ageing parameters have a substantial influence on the ferrite substructure and thedegree of coherence, dispersion and amount of the ?-Cu phase. The ageing treatment at 480?C causes, in additionto the precipitation of the ?-Cu phase coherent with the matrix, the formation of a ?’-Cr phase and an ?-Fe phase.Practical implications: Duplex cast steels are becoming an irreplaceable material in the elements of equipmentexposed to the simultaneous action of corrosive and erosive environment. In the case of massive elements, suchas pump (rotors and guide vanes and pipeline elements etc., which are operated in corrosive environments ofwater suspensions of solids of different type and gradation, the effect of ageing will be much lower than in smalllaboratory specimens, which is associated with the presence of a large amount of the incoherent ?-Cu phase inthe cast steel after the solution heat treatment.Originality/value: The lower limit of ageing temperature (480?C coincide with the temperature of anundesirable spinodal decomposition of the ferrite, which is partially responsible for the slight increase inhardness and a drop in plastic properties. This is the indication that the lower temperature of ageing duplex caststeels with copper should not be lower than 500?C.

  18. Identification of corrosion shape by EMAT

    International Nuclear Information System (INIS)

    This paper is concerned with quantitative evaluation of corrosion shape on back surface of Stainless samples by Electro Magnetic Acoustic Transducer (EMAT). First we summarize numerical studies of the quantitative nondestructive evaluation by EMAT. Secondly, a method for recovering corrosion shape is proposed. Aspect ratio (corrosion height/corrosion radius) is important for recovery a corrosion shape. (author)

  19. UK corrosion 90. V. 1-3

    International Nuclear Information System (INIS)

    This volume contains 30 papers presented at the Conference. They are collected together under the following headings: corrosion science; cathodic protection; boiler and coding water treatments to control corrosion; high temperature corrosion; waxes and asphatenes. A separate abstract has been prepared for the one paper dealing with corrosion specifically related to nuclear facilities; namely, crevice corrosion in BWRs. (UK)

  20. CHECWORKS integrated software for corrosion control

    International Nuclear Information System (INIS)

    CHECWORKS, a comprehensive software package for managing Flow-Accelerated Corrosion (FAC, also called erosion-corrosion and flow-assisted corrosion) concerns, is expanding to include other systems and other aspects of corrosion control in CANDU reactors. This paper will outline CHECWORKS applications at various CANDU stations and further plans for CHECWORKS to become a code for comprehensive corrosion control management. (author)