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Sample records for vascular corrosion casts

  1. Vascular corrosion casting of human heart

    J. Vasudeva Reddy

    2013-06-01

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

  2. [Microscopic vascular study of the colon with the corrosion casting technique].

    Brevet, M; Plaisant, O; Gillot, C; Costiou, P; Diebold, M D

    2002-03-01

    The aim of this study is, firstly, to assess the accuracy of vascular casts obtained at various times after death and secondly to describe the mucosal microvascular architecture of the cat colon. Two injections were realized, the first one on a non-embalmed human corpse, 12 days after the death, and the other one on a cat, immediately following euthanasia. Results show that this second cast seems finer and more detailed than the cast stemming from the human corpse; indeed, the finest vessels obtained are about 6 microns while they are about 15 microns on the human corpse. This could be explained by a post-mortem obstruction of microvessels, that prevented the passage of the injected product or by an insufficient amount of product injected. Finally, the vascular cast of the cat colic mucosa presents a regular honeycomb-like network that bounds the colonic mucosal glands, a finding consistent with the results reported previously. PMID:12035668

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

    Aharinejad, S; Lametschwandtner, A.

    1992-01-01

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

  4. The vascular architecture of the supravaginal and vaginal parts of the human uterine cervix: a study using corrosion casting and scanning electron microscopy

    Bereza, Tomasz; Tomaszewski, Krzysztof Andrzej; Bałajewicz-Nowak, Marta; Mizia, Ewa; Pasternak, Artur; Walocha, Jerzy

    2012-01-01

    The aim of this study was to visualize and describe the vascular architecture of the vaginal and supravaginal parts of the human uterine cervix. Uteri collected at autopsy (n = 42) were perfused via the afferent vessels with fixative followed by Mercox resin. After polymerization of the resin, corrosion was performed. The obtained vascular casts of the cervix, visualizing all vessels including capillaries, were examined using scanning electron microscopy. Both in the vaginal and supravaginal parts of the cervix, four distinct vascular zones were distinguished – the outer zone containing large arteries and veins, the arteriole and venule zone, the endocervical mucosal capillaries zone and the pericanalar zone containing small veins and capillaries. In the pericanalar zone ran small veins, responsible for draining the mucosal capillaries. Both in the muscular layer, as well as in the pericanalar zone, arterioles and venules passed close to each other, often adjoining. This study introduces the idea of two systems responsible for draining blood from the mucosal capillaries. It is also the first to suggest the possible existence of a countercurrent transport between adjoining veins and arteries. PMID:22844876

  5. Rust and corrosion resistant cast steel

    An austenite-ferritic chromium-nickel (molybdenum) steel alloy is used to manufacture rust and corrosion-resistant, weldable casting steel without thermal treatment. The alloy exhibits a minimum yield strength of 35-45 kg/mm2 and tensile strength of between 55-65 kg/mm2 depending on the ferrite content. (IHOE)

  6. Experimental Investigation on Corrosion of Cast Iron Pipes

    Mohebbi, H; C. Q. Li

    2011-01-01

    It is well known that corrosion is the predominant mechanism for the deterioration of cast iron pipes, leading to the reduction of pipe capacity and ultimate collapse of the pipes. In order to assess the remaining service life of corroded cast iron pipes, it is imperative to understand the mechanisms of corrosion over a long term and to develop models for pipe deterioration. Although many studies have been carried out to determine the corrosion behavior of cast iron, little research has been ...

  7. Structural and phase heterogeneity of cast austenitic corrosion resisting steels

    Structure of large-size castings of austenitic corrosion-resistant steel type 08Kh18N10T was under study. Consideration was given to peculiar features of crystallization as well as to distribution of ?-ferrite, austenite- and ferrite forming elements and nonmetallic inclusions in steel castings. Casting defects and causes of their formation were investigated

  8. Partial corrosion casting to assess cochlear vasculature in mouse models of presbycusis and CMV infection.

    Carraro, Mattia; Park, Albert H; Harrison, Robert V

    2016-02-01

    Some forms of sensorineural hearing loss involve damage or degenerative changes to the stria vascularis and/or other vascular structures in the cochlea. In animal models, many methods for anatomical assessment of cochlear vasculature exist, each with advantages and limitations. One methodology, corrosion casting, has proved useful in some species, however in the mouse model this technique is difficult to achieve because digestion of non vascular tissue results in collapse of the delicate cast specimen. We have developed a partial corrosion cast method that allows visualization of vasculature along much of the cochlear length but maintains some structural integrity of the specimen. We provide a detailed step-by-step description of this novel technique. We give some illustrative examples of the use of the method in mouse models of presbycusis and cytomegalovirus (CMV) infection. PMID:26707615

  9. STUDY OF RENAL APICAL SEGMENTAL ARTERY BY CORROSION CAST METHOD

    Ram Kumar,; Satyam; Shilpi; Rashmi,; Priti

    2015-01-01

    The advent of more conservative methods, practiced in modern urinary surgery, necessitated a perfect and precise knowledge of the renal arterial supply. The main objective of the study was to observe the pattern of renal apical segmental artery in human kidneys and its variations by corrosion cast method . Corrosion casting is a very useful method which allows three dimensional visualization of micro vessels. Sixty (thirty pairs) human kidneys were obtained...

  10. Evaluation of Accelerated Graphitic Corrosion Test of Gray Cast Iron

    In operating nuclear power plants, gray cast iron is commonly used as materials for various non-safety system components including pipes in fire water system, valve bodies, bonnets, and pump castings. In such locations, operating condition does not require alloy steels with excellent mechanical properties. But, a few corrosion related degradation, or graphitic corrosion is frequently occurred to gray cast iron during the long-term operation in nuclear power plant. Graphitic corrosion is selective leaching of iron from gray cast iron, where iron gets removed and graphite grains remain intact. In U.S.A., one-time visual inspection and hardness measurement are required from regulatory body to detect the graphitic corrosion for the life extension evaluation of the operating nuclear power plant. In this study, experiments were conducted to make accelerated graphitic corrosion of gray cast iron using electrochemical method, and hardness was measured for the specimens to establish the correlation between degree of graphitic corrosion and surface hardness of gray cast iron

  11. Vascular corrosion casting of human heart

    J. Vasudeva Reddy; S. Lokanadham

    2013-01-01

    Variation in the morphological pattern of coronary arteries and their major branches is an important factor in the assessment and treatment of coronary heart disease. Detailed knowledge of the blood supply of the heart is necessary today because of the wider practice of cardiac surgery, and also for better understanding of the anomalous branches, anastomosis and dominance pattern in circulation caused by coronary vasculature. We utilized 80 human heart specimens and found right dominance in 6...

  12. Corrosion Resistance of High-Alloyed White Cast Iron

    Kawalec M.

    2015-04-01

    Full Text Available The paper presents the results of corrosion resistance tests carried out on high-alloyed white cast iron. Tests were performed in 0.1 M NaCl by the technique of linear voltammetry. The test material was collected from six high-vanadium cast iron melts with a variable content of carbon and vanadium, and thus with different microstructure. Studies have confirmed that the type of crystallised microstructure has a very important effect on the alloy corrosion resistance. The highest corrosion resistance showed the alloy with a ferritic matrix containing the spheroidal precipitates of vanadium carbide VC, while the lowest had the eutectic alloy with a pearlitic matrix.

  13. Chemical corrosion in cast iron in soil-water medium.

    Mukesh, K; Panday, Y D

    2001-02-01

    Grey cast iron metal strips were allowed to rust in varying compositions of soil-water media under the controlled environment. The process of corrosion was monitored by non-electrochemical method. Assessment of the extent of corrosion was carried out, both visually and by the method of weight loss coupons. It was found that a 80:20 weight:volume percent (w/v%) composition caused the most severe case of corrosion over a period of seven days. It was also observed that the corrosion in cast iron obeyed the relation, D = ktn [10]. The value of 'n' increased as corrosion became more severe. Gravimetric analysis and evidence from the Scanning Electron Microscopy (SEM) proved that gamma-FeOOH was one of the intermediates of corrosion in grey cast iron in soil-water media. An attempt has also been made to propose a mechanism for the corrosion in cast iron strips in soil-water media. It was found to be consistent with the one proposed by McEnaney and Smith [11]. PMID:11349372

  14. STUDY OF RENAL APICAL SEGMENTAL ARTERY BY CORROSION CAST METHOD

    Ram Kumar

    2015-10-01

    Full Text Available The advent of more conservative methods, practiced in modern urinary surgery, necessitated a perfect and precise knowledge of the renal arterial supply. The main objective of the study was to observe the pattern of renal apical segmental artery in human kidneys and its variations by corrosion cast method . Corrosion casting is a very useful method which allows three dimensional visualization of micro vessels. Sixty (thirty pairs human kidneys were obtained from the cadavers in Anatomy Department of Subharti Medical College, Meerut after ethical clearance from ethical committee and corrosion casts were prepared by infusing red colored butyl butyrate solution in renal arteries through abdominal aorta. Variations in the apical arterial supply of hum an kidneys have been frequently observed. The present study is a modest venture to further elucidate the renal apical arterial supply by corrosion cast technique. Most frequent origin of apical artery observed was from posterior division of renal artery (4 3%. This study will be helpful to urologic surgeons in nephrectomy and renal transplants

  15. Stress Corrosion Cracking Behavior of Cast Stainless Steels

    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.

  16. Corrosion resistant high silicon cast iron

    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)

  17. Galvanic corrosion of copper-cast iron couples

    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 μm/year for iron were observed after deaeration, but the corrosion rates were near 100 μm/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 consumption by corrosion of the cast iron insert or by reaction with the surrounding matrix, the galvanic corrosion currents will fall markedly to values close to the corrosion rate of uncoupled cast iron

  18. Heat-transfer corrosion behaviour of cast Al alloy

    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

  19. Heat-transfer corrosion behaviour of cast Al alloy

    Zhou Wei [Precision Engineering and Nanotechnology Centre, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)], E-mail: mwzhou@ntu.edu.sg; Aung, Naing Naing [Precision Engineering and Nanotechnology Centre, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Choudhary, Anil [Ciba Specialty Chemicals (India) Limited, Mumbai 400 053 (India); Kanouni, Mouhcine [Global Applications Center, Ciba Specialty Chemicals Corporation, 540 White Plains Road, Tarrytown, NY 10591 (United States)

    2008-12-15

    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 {alpha}-Al matrix. Crevice corrosion was predominant at oxygen depleted regions in heat-transfer corrosion cell. Al{sub 2}Cu, Al{sub 15}(Fe,Mn){sub 3}Si{sub 2} dendrites, Al{sub 4}Cu{sub 2}Mg{sub 8}Si{sub 7} and Si phases served as the effective cathodes resulting microgalvanic corrosion at the anodic site of {alpha}-Al matrix.

  20. Corrosion Behavior of A356-10 Vol.% SiC Composites Cast by Gravity and Squeeze Casting in H2SO4 Solutions

    A. Fattah-Alhosseini; Ranjbaran, M.; S. Vajdi Vahid

    2014-01-01

    Corrosion behavior of A356-10 vol.% SiC composites cast by gravity and squeeze casting is evaluated. For this purpose, prepared samples were immersed in H2SO4 solution for 2?hrs. at open circuit potential. Tafel polarization and electrochemical impedance spectroscopy (EIS) were carried out to study the corrosion resistance of composites. The results showed that corrosion resistance of composites cast by squeeze casting is higher than that of the gravity cast composites. The micrographs of sca...

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

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

  2. Cerium effect on corrosion-electrochemical properties and structure of cast chromium steel

    Cerium effect on corrosion properties and structure of cast chromium ferrite steel 06X18T is studied. It is shown that cerium additions (0.1 and 0.5% according to calculation) in 5-30% sulfuric acid solution decrease generae corrosion rate, improve anode passivity due to increase in resistance to intercrystalline corrosion. It is shown that favourable cerium effect on corrosion-electrochemical properties of cast ferrite steel 06X18T is caused by change of its microstructure and nature of nonmetallic inclusions. Interconnection between resistance of steel, modified by cerium, to pitting corrosion with melting conditions and position of investigated zone in ingots is noted

  3. Characteristics of low nickel ferritic-austenitic corrosion resistant cast steel

    B. Kalandyk; Zapała, R.; Sobula, S.; M. Górny; Ł. Boroń

    2014-01-01

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

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

    Saliu Ojo SEIDU; Owoeye, Seun Samuel; Helen Tola OWOYEMI

    2015-01-01

    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, b...

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

    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.

  6. Vasculature of the ophthalmic rete in night herons (Nycticorax nycticorax): scanning electron microscopy of corrosion casts.

    Ninomiya, Hiroyoshi

    2002-09-01

    Vasculature of the ophthalmic rete (rete ophthalmicum) in the night heron (Nycticorax nycticorax) was studied using scanning electron microscopy of vascular corrosion casts and light microscopy on tissue sections. Most blood to the eyeball and a lesser volume of blood to the brain passed through the ophthalmic rete via the external ophthalmic artery. The collateral retial arterioles originated from the external ophthalmic artery forming a flat and fusiform-shaped arterial network at the ventrotemporal region of the eyeball. The arterial network was intermixed with a similar complex of the veins from the eye. The ophthalmotemporal artery, which supplied the eyeball posteriorly, and supraorbital and infraorbital arteries, which supplied the eyeball anteriorly, originated from the rete. Blood from the eye, which is a site of potential heat loss, drained into the ophthalmic rete via the ophthalmotemporal vein. On the casts of retial arterioles, slit-like cleavages at branching sites representing flap valves, which might play a role as sluice valves, were seen. In addition, marks of circularly running grooves, which might represent tufts of smooth muscle cells and might contribute to a sphincter activity, were observed. These anatomical specializations of the avian ophthalmic rete, involving parallel arrangement of arteries and veins, may function to facilitate counter-current heat exchange and to regulate blood pressure and volume to the eye and the brain. PMID:12236865

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

    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.

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

    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.

  9. Corrosion Mechanisms of Steel and Cast Iron by Molten Aluminum

    Balloy, David; Tissier, Jean-Charles; Giorgi, Marie-Laurence; Briant, Marc

    2010-09-01

    The corrosion mechanisms by liquid aluminum of three industrial materials have been studied: unalloyed steel (UAS), and ferritic and modified pearlitic cast irons (FCI and PCI, respectively). The behavior of these materials when in contact with liquid aluminum is different. Aluminum diffuses deep into the UAS and forms intermetallic compounds with iron at the surface and in the steel matrix. At the surface, only Fe2Al5 and FeAl3 are found. In the matrix, FeAl2 also is formed in agreement with the equilibrium Fe-Al diagram. From the matrix to FeAl2, the Al content in the ferrite increases progressively until Al saturation is reached. At this step, black elongated precipitates (Al4C3 and/or graphite) appear. Graphite lamellas present in both FCI and PCI constitute an efficient barrier to the Al diffusion. The high silicon content of the FCI leads to the formation of a phase free from Al and saturated in Si. For the PCI, a thin layer rich in Al and Si, which is formed between the matrix and Fe2Al5, limits the diffusion of atoms. The effects of Cr and P added in the PCI also are discussed.

  10. Improved corrosion resistance of cast carbon steel in sulphur oxides by Alonizing

    The results of studies on the Alonizing of cast steel and of testing the corrosion resistance of this cast steel in an atmosphere containing 5 to 6% SO2 + 50% SO3 at 853 K are described and compared with the results obtained with unalonized cast carbon steel and high-alloy 23Cr-8Ni-2Mo cast steel. The duration of the corrosion tests was 336 hours. The aluminium diffusion layer on cast carbon steel was obtained by holding the specimens in a mixture containing 99% of powered Fe-Al and 1% of NH4Cl at 1323 20 K. The holding time was 10 and 20 hours, respectively. The aluminium layer formed on the cast carbon steel was examined by optical microscopy and an X-ray microanalysis. After Alonizing for 10 h the layer had reached a thickness of 950 ?m, and contained up to 35% Al. In a mixture of sulphur oxides corrosion rate of the alonized cast carbon steel was by about 600 times lower than of the unalonized cast carbon steel, and by about 50 times lower than that of the 23Cr-8Ni-2Mo cast steel. (orig.)

  11. A Moessbauer spectroscopy study of the corrosion of nodular cast iron in mine waters

    The corrosion of ductile cast iron in water containing different amounts of chloride ions was investigated under both static and dynamic conditions. Corrosion/time relationships were established for exposure times of up to 30 days. Post-corrosion investigations were performed, employing Moessbauer spectroscopy, optical microscopy and electrochemical techniques. It was found that the nature of the surface corrosion product formed under static conditions differed morphologically and chemically from that formed under dynamic conditions. The latter was a hard layer consisting of a mixture of ?- and ?-FeOOH (situated on an underlying cementite layer), whereas the static tests resulted in a soft, spongy corrosion product, identified as ?-FeOOH. (orig.)

  12. Study of biofilm influenced corrosion on cast iron pipes in reclaimed water

    Zhang, Haiya; Tian, Yimei; Wan, Jianmei; Zhao, Peng

    2015-12-01

    Biofilm influenced corrosion on cast iron pipes in reclaimed water was systemically studied using the weight loss method and electrochemical impedance spectroscopy (EIS). The results demonstrated that compared to sterile water, the existence of the biofilm in reclaimed water promoted the corrosion process significantly. The characteristics of biofilm on cast iron coupons were examined by the surface profiler, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The bacterial counts in the biofilm were determined using the standard plate count method and the most probable number (MPN). The results demonstrated that the corrosion process was influenced by the settled bacteria, EPS, and corrosion products in the biofilm comprehensively. But, the corrosion mechanisms were different with respect to time and could be divided into three stages in our study. Furthermore, several corresponding corrosion mechanisms were proposed for different immersion times.

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

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

    2011-01-01

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

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

    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

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

    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.

  16. The development of the endotheliochorial mink placenta: light microscopy and scanning electron microscopical morphometry of maternal vascular casts.

    Pfarrer, C; Winther, H; Leiser, R; Dantzer, V

    1999-01-01

    The development of the mink endotheliochorial placenta has been studied by means of light microscopy and scanning electron microscopy of maternal vascular corrosion casts. The placental blood vessels of three groups of mink, representing early, intermediate and near-term gestational ages were either perfusion fixed for histology, or instilled with liquid plastic in order to prepare vascular casts, which were examined qualitatively and/or quantitatively. The maternal component of the placental vascular system evolves from preimplantation blood vessels between the endometrial glands, into which the initial feto-maternal contact is made. The influence of highly invasive syncytiotrophoblast provokes a transition of the maternal capillaries into extensively anastomosing sinusoids with a subsequent modification of their endothelial cells into large cells with luminal protrusions. Three-dimensionally, the sinusoids are arranged as vascular crypts. This implies a villous-crypt type of interdigitation for the mink, but since the fetal capillaries surround the maternal sinusoids as a dense network a labyrinth is formed. The vascular crypts are supplied by very short arterioles, branching from maternal stem arteries, which arise from branches of the uterine artery and move straight to the surface of the endometrium. Venous outlets of the sinusoids converge onto venules and large stem veins in the deepest portion of the endometrium. This architectural pattern persists until term. Morphometry was used to confirm the qualitative observations in vascular casts. The diameter of maternal vascular crypts significantly increased from 137.3+/-21.9 microm in early gestation up to 217.8+/-80.9 microm in the intermediate stage and 431.8+/-119.5 microm near-term, when compared to the paraplacental zone in early gestation (82.2+/-19.5 microm). The capillary or sinusoidal diameter also increased significantly from intermediate stage (42.9+/-11.8 microm) to near term (60.1+/-16.7 microm), whereas the difference in the paraplacental zone (7.3+/-2.1 microm) and early gestation (13.0+/-3.2 microm) was not statistically significant. PMID:9924936

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

    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.

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

    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

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

    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.

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

    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)

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

    J. Gawro?ski

    2010-01-01

    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/...

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

    B. Bobic

    2011-06-01

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

  3. Fabrication of corrosion resistant steel with using continuous-casting slab machine

    The technology of producing corrosion-resistant 08-12Kh18N10T steel using new technological operations during out-of-the-furnace steel treatment is developed and exploited. The reduction of gas saturation of steel delivered to the machine of continuous casting, the decrease in the amount of nonmetallic inclusions, stabilization of the process in temperature and rate contribute to the increase in quality of continuously casted slabs

  4. Comparison of corrosion and oxygen evolution behaviors between cast and rolled Pb-Ag-Nd anodes

    Zhong, Xiao-cong; Yu, Xiao-ying; Liu, Zheng-wei; Jiang, Liang-xing; Li, Jie; Liu, Ye-xiang

    2015-10-01

    The corrosion and oxygen evolution behaviors of cast and rolled Pb-Ag-Nd anodes were investigated by metalloscopy, environmental scanning electron microscopy, X-ray diffraction analysis, and various electrochemical measurements. The rolled anode exhibits fewer interdendritic boundaries and a dispersed distribution of Pb-Ag eutectic mixtures and Nd-rich phases in its cross-section. This feature inhibits rapid interdendritic corrosion into the metallic substrate along the interdendritic boundary network. In addition, the anodic layer formed on the rolled anode is more stable toward the electrolyte than that formed on the cast anode, reducing the corrosion of the metallic substrate during current interruption. Hence, the rolled anode has a higher corrosion resistance than the cast anode. However, the rolled anode exhibits a slightly higher anodic potential than the cast anode after 72 h of galvanostatic polarization, consistent with the larger charge transfer resistance. This larger charge transfer resistance may result from the oxygen-evolution reactive sites being blocked by the adsorption of more intermediates and oxygen species at the anodic layer/electrolyte interfaces of the rolled anode than at the interfaces of cast anode.

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

    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

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

    M. Starowicz

    2009-10-01

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

  7. Corrosion Inhibition of Cast Iron in Arabian Gulf Seawater by Two Different Ionic Liquids

    El-Sayed M. Sherif

    2015-06-01

    Full Text Available In this paper we report on the corrosion inhibition of cast iron in Arabian Gulf seawater by two different ionic liquids namely, 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl and 1-butyl-1-methylpyrrolidinium chloride ([Py1,4]Cl. The inhibiting influence of the employed ionic liquids was investigated by weight loss, open circuit potential electrochemical impedance spectroscopy, and cyclic potentiodynamic polarization. The results show the corrosion inhibition impact of the employed ionic liquids (ILs. Compared with [Py1,4]Cl, [EMIm]Cl shows a higher inhibition efficiency at a short immersion time, for the examined ILs concentrations. However, [Py1,4]Cl exhibits a higher efficiency upon increasing the immersion time indicating the persistence of the inhibiting influence. The corrosion inhibition of the employed ionic liquids is attributed to the adsorption of the cations of the ionic liquids onto the surface of cast iron forming a corrosion barrier.

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

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

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

    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.

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

    Paglia, C.S. [University of Applied Sciences of Southern Switzerland, DACD, Laboratory of Technical and Experimental Studies, Trevano, CP 12, 6952 Canobbio (Switzerland)]. E-mail: christian.paglia@supsi.ch; Jata, K.V. [Metals, Ceramics and NDE Division, Materials and Manufacturing Directorate, AFRL/MLL, 2230 Tenth Street, Wright-Patterson Air Force Base, OH 45433 (United States); Buchheit, R.G. [Ohio State University, Department of Materials Science and Engineering, 477 Watts Hall 2041 College Road, Columbus, OH 43210-1179 (United States)

    2006-05-25

    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.

  11. Corrosion Inhibition of Cast Iron in Arabian Gulf Seawater by Two Different Ionic Liquids

    Sherif, El-Sayed M.; Hany S. Abdo; Sherif Zein El Abedin

    2015-01-01

    In this paper we report on the corrosion inhibition of cast iron in Arabian Gulf seawater by two different ionic liquids namely, 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) and 1-butyl-1-methylpyrrolidinium chloride ([Py1,4]Cl). The inhibiting influence of the employed ionic liquids was investigated by weight loss, open circuit potential electrochemical impedance spectroscopy, and cyclic potentiodynamic polarization. The results show the corrosion inhibition impact of the employed ionic l...

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

    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 studies of the corrosion of Mg alloys

  13. Improvements in continuous casting of corrosion resistant steel

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

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

    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 β transus. All of the samples exhibited active-passive transitions in deaerated 5% HCl at room temperature, but the β 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 α and β phases.

  15. Corrosion of Cast Iron Mill Plates in Wet Grinding

    Anthony ANDREWS

    2010-12-01

    Full Text Available Corrosion studies were carried out on two different maize grinding plates. Maize was soaked in water for three days and the water decanted and used as electrolyte. Mass loss and pH measurements were carried out every 3 days for 15-day period. Results show that, for each plate, mass loss and pH increased with exposure time. Corrosion rates determined from mass loss data was found to be strongly dependent on pH. The observed behaviour may be explained in terms of the chemical composition and/or microstructures of the plates. Results are briefly discussed in terms of the contribution of corrosion to wear.

  16. Effect of tempering on corrosion resistance of cast aluminium bronzes

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

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

    Cheng, Xiu; Hu, Shubing; 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.

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

    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.

  19. Microstructure and Corrosion Performance of Carbonitriding Layers on Cast Iron by Plasma Electrolytic Carbonitriding

    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 element of -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. (condensed matter: structure, mechanical and thermal properties)

  20. Atmospheric corrosion rate expressed as a function of time. Effects of atmospheric conditions and alloying elements on corrosion resistance of steels and cast irons

    On the basis of function describing a change in atmospheric corrosion rate (K) in time (t) the published results of long-standing corrosion tests of a great number of cast irons and steels were statistically processed. The effect of chloride - ions, sulfur dioxide, alloying elements (Cu, Ni, Cr, Mn, Si, V, C) on the rate of initial corrosion on the active surface (K0), passivation properties (?0) of corrosion products and corrosion resistance (?0/K0) of iron-carbonic alloys in different climatic areas was revealed. The data permit further investigation of the mechanism of alloying element effect on atmopsheric corrosion of steels

  1. Corrosion of Cast Iron Mill Plates in Wet Grinding

    Anthony ANDREWS; Samuel KWOFIE

    2010-01-01

    Corrosion studies were carried out on two different maize grinding plates. Maize was soaked in water for three days and the water decanted and used as electrolyte. Mass loss and pH measurements were carried out every 3 days for 15-day period. Results show that, for each plate, mass loss and pH increased with exposure time. Corrosion rates determined from mass loss data was found to be strongly dependent on pH. The observed behaviour may be explained in terms of the chemical composition and/or...

  2. Evolution of corrosion in cast Al alloy in antifreeze radiator coolant

    Zhou, W.; Aung, N.N. [Precision Engineering and Nanotechnology Centre, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Choudhary, A. [Ciba Specialty Chemicals (India) Limited, Mumbai 400 053 (India); Kanouni, M. [Global Applications Center, Ciba Specialty Chemicals Corporation, 540 White Plains Road, Tarrytown, NY 10591 (United States)

    2008-12-15

    Corrosion is an important issue for cast Al alloy in an engine cooling system, but how the microstructural features affect the coolant-related corrosion behaviour is not well understood. In this research, the evolution of corrosion in an ISO 2379 cast Al alloy was studied in an antifreeze radiator coolant under heat-rejecting conditions. Extensive analyses of microstructures and corroded surfaces were carried out using an optical microscope, scanning electron microscope equipped with energy dispersive spectroscopy and X-ray diffractometer. Intergranular cavitation corrosion was observed to occur at interfaces between {alpha}-Al matrix and intermetallics (Al{sub 2}Cu and Al{sub 5}FeSi) or to a less degree at interfaces between {alpha}-Al matrix and Si phase. The large area fraction of the cathodic phases (Al{sub 2}Cu, Al{sub 5}FeSi and Si) led to the galvanic coupling between them and the adjacent anodic {alpha}-Al matrix. The heat-rejecting condition in antifreeze radiator coolant was favourable condition to cavitation process while severe crevice corrosion was predominant at oxygen-depleted regions in the heat-transfer corrosion cell. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  3. Characteristics of low nickel ferritic-austenitic corrosion resistant cast steel

    B. Kalandyk

    2014-10-01

    Full Text Available The article presents the results of microscopic examinations of corrosion resistant cast steel with reduced nickel content obtained in a test casting with varying wall thickness. Investigations were carried out in as-cast condition and after heat treatment. Regardless of the casting wall thickness, increasing the manganese and nitrogen content to about 5 % and 2 500 ppm, respectively, yields the material with a two-phase microstructure containing ferrite in an amount of 55,6 ÷ 57,2 % (magnetic method and 52,3 ÷ 55,2 % (analytical method. Based on the results of metallographic examinations, total elimination of the secondary austenite from the microstructure was observed. Microhardness measurements showed average values of 352,3 μHV20 and 267 μHV20 for the chromium ferrite and austenite, respectively.

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

    J. Gawroński

    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.

  5. Effects of tungsten on erosion-corrosion behavior of high chromium white cast iron

    In this study, effects of tungsten on wear resistance of high chromium white cast iron with and without tungsten in erosion-corrosion condition have been investigated. At the same time, the comparison between wear resistance of this grade of cast iron and low alloy steels with various contents of Cr which are used in industrial condition (in Sarcheshme Company, the greatest copper production company in the Middle East and with more than 4000 years historical cupper production background) was studied, while, copper concentrates have used for erosion particles. Results show that, because of higher hardness of matrix due to the tungsten, the wear resistance of high chromium cast iron increases. In addition to that, combine cutting and deformation wear mechanism and spalling mechanism were attributed in high chromium cast iron and low alloy steels, respectively. Subsequently, pitting mechanism in corrosion aspect was recognized because of inhomogeneity in chemical composition and sulfide inclusions content. Finally, the combine effects of erosion and corrosion (synergetic effect) were recognized in the high chromium white iron in industrial condition for the damaged samples

  6. Oxidation and corrosion fatigue aspects of cast exhaust manifolds

    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...

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

    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

  8. Wear, corrosion, and cavitation erosion characteristics of laser-surface-alloyed gray cast iron

    Bransden, Antony S.; Tomlinson, W. J.

    1990-10-01

    There is significant industrial interest in methods to improve the surface properties of cast iron. This paper describes investigations of laser treatments to enhance cast iron surfaces by alloying with the elements chromium, nickel or cobalt, or a cobalt/chromium mixture. The coatings achieved are of high integrity, low porosity and uniform in composition, microstructure and hardness. Alloyed surfaces have been subjected to corrosion testing in a range of acids and to wear and cavitation erosion in distilled and salt waters. The data show substantial improvements over those obtained from unalloyed material. Results are presented and discussed including the response of the microstructure to the testing environments.

  9. The role of soil in the external corrosion of cast iron water mains in Toronto, Canada

    External corrosion is a major factor contributing to the deterioration of cast iron water mains; it weakens the pipe wall, which increases the risk of failure. External corrosion is a function of the interaction between the pipeline and the soil that surrounds it. The aggressiveness of soil towards cast iron is affected by soil properties such as resistivity, pH, and the presence of sulphate reducing bacteria. Water main sections and accompanying soil samples were collected from locations across Toronto within the framework of a comprehensive research project over a 2 year period. After careful examination of the effect of each of the soil properties, it appears that soil resistivity has the largest effect on the observed maximum average pitting rate. Limitations to the practical application of the American Water Works Association soil corrosiveness scoring system are also presented. A preliminary spatial analysis of the data indicates that water mains in the district of Etobicoke have had a higher average rate of external corrosion than those in the district of Toronto. Microbiological corrosion could be an aggravating factor in the district of Etobicoke, since areas exhibiting increased levels of sulphide concentration were identified in soils that had originated from this district. (author)

  10. Microstructure and corrosion behavior of cast Fe-B alloys dipped into liquid zinc bath

    The corrosion behavior of cast Fe-B alloys in a liquid zinc bath was examined. As a result, the as-cast Fe-3.5B alloy displays the best corrosion resistance in all tested specimens owing to its netlike structure of eutectic Fe2B against the liquid zinc. XRD and EDS results indicate that the main phases in the corrosion layer are determined to be ?, ? and ? from the matrix to the zinc zone, respectively. The corrosion process is controlled by the diffusion of zinc atoms and the dissolution mechanism. According to the observations, only three steps occur in the whole dissolution process: the preferential dissolution of ?-Fe, the formation of intermetallic compounds, and the spalling of Fe2B caused by cracks that mainly result from the internal stress produced by Fe/Zn phase transformation. The continuous netlike Fe2B phase delays the further reaction of Fe/Zn and hinders the diffusion of zinc atoms between the substrate and liquid zinc effectively, improving corrosion resistance of Fe-B alloy in comparison with 1Cr18Ni9Ti stainless steel.

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

    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.

  12. High temperature corrosion of cast irons and cast steels in dry air

    Tholence, F.; Norell, M. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Engineering Metals

    2001-07-01

    The oxidation in dry air of four cast alloys intended for exhaust gas systems has been examined. Particular interest was directed to how the oxide growth was related to the microstructures. The examined alloys were two cast ductile irons, a SiMo alloy (Fe3,86Si0,6Mo3C) and a Ni-Resist alloy (Fe32Ni5,3Si2,1C), and two cast stainless steels, one ferritic (Fe18Cr2,1Mn0,32C) and one austenitic (Fe20Cr9Ni0,47C). Coupons were oxidised for 50 h at temperatures between 650 C and 1050 C. The samples were characterised by using XRD, SEM/EDX and AES. As expected, the overall oxide thickness increased with temperature and partial spallation occurred at the highest temperatures for all alloys. Porous Fe oxide nodules nucleate at the graphite nodules on the ductile irons. These Fe-oxide nodules formed above a continuous layer of Fe-Si-oxide for the SiMo and mixed Fe-Ni-Si oxides for the Ni-Resist. The total oxide thickness is about (60 {mu}m). Thick oxides at the interdendritic regions in the cast steels were attributed to non-Cr-carbides. Segregation of Cr directed the formation of iron oxide nodules to the centre of the dendrites in the austenitic alloy. (orig.)

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

    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

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

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

    2014-08-01

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

  15. CORROSION RESISTANCE OF PEARLITIC AND BAINITIC CAST IRON IN A SYNTHETIC SOLUTION OF CONDENSED GAS FROM COMBUSTION

    Sandra Matos Cordeiro Costa

    2015-03-01

    Full Text Available The corrosion of engine components of the combustion chamber is usually related to the formation of acids such as sulfuric and nitric. These acids are generated by the condensation of combustion gases that usually occur in vehicle exhaust systems. However, with the development of new technologies to reduce emissions, condensation is also being promoted in vehicle combustion chambers. This fact is associated with high exhaust gas recirculation rates, known as EGR (English term for Exhaust Gas Recirculation. Consequently, corrosion problems in the engine components are increasing, especially in cylinder liners alloy manufactured using cast iron. In this study, the corrosion resistance of two cast iron alloys, one with a pearlitic microstructure and the other with a bainite microstructure in a solution simulating the composition of the condensate obtained from the combustion gases. It was found that the microstructure of the cast iron is an important factor affecting the corrosion behavior. The results showed that none of the two materials investigated is resistant to corrosion in the test medium, and the small difference observed between the behavior of the two cast iron was related to its microstructure, which are dependent on their chemical compositions. The cast iron with a pearlitic microstructure showed less formation of corrosion products than the bainitic cast iron. This result is related to the presence of steadite phase, highly stable and resistant to corrosion in pearlitic microstructure. This phase (steadite anchors the corrosion products formed on the surface and act as a partial barrier slowing the progress of the corrosion process, that was more pronounced in the bainitic cast iron.

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

    El-Sayed M. Sherif; Hany S. Abdo; Almajid, Abdulhakim A.

    2015-01-01

    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 i...

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

    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)

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

    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.)

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

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

    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...

  20. Corrosion Inhibiting Mechanism of Nitrite Ion on the Passivation of Carbon Steel and Ductile Cast Iron for Nuclear Power Plants

    Kim, K. T.; Kim, H. W.; Chang, H.Y.; B. T. Lim; Park, H B; Kim, Y S

    2015-01-01

    While NaNO2 addition can greatly inhibit the corrosion of carbon steel and ductile cast iron, in order to improve the similar corrosion resistance, ca. 100 times more NaNO2 addition is needed for ductile cast iron compared to carbon steel. A corrosion and inhibition mechanism is proposed whereby NO2- ion is added to oxidize. The NO2- ion can be reduced to nitrogen compounds and these compounds may be absorbed on the surface of graphite. Therefore, since nitrite ion needs to oxidize the surfac...

  1. Corrosion behaviour of unalloyed steel, cast steel and cast iron as final storage canister material in water-bearing granite rocks

    During final storage of radioactive waste the corrosion behaviour of the canister materials is an important parameter. In this study the external corrosion behaviour of unalloyed steel, cast steel and cast iron in water-bearing granite rocks is discussed with a particular view to the conditions in Switzerland (temperature, pressure, water composition, etc.). The report is based on a critical literature review, on the author's own experience and on experience from other fields of technology. Furthermore, model calculations are made for corrosion rates to be expected in the presence of a mass transfer barrier. The most important results are as follows: -corrosion rates in waters and soils are low, provided oxygen is excluded or protective layers are formed, -under the expected conditions all of the relevant waters can produce significant corrosion, -the pressure dependence of the corrosion rate is small, while the temperature dependence is large, -in the presence of an effective convection and diffusion barrier (bentonite) the corrosion rate is very small (10-5 mm/year), -if such a barrier maintains its properties for the required lifetime of the final storage system the corrosion rate of the canister material can be neglected. (author)

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

    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

  3. Corrosion-resistant iron thin films formed by pulsed laser deposition with cast iron targets

    Okoshi, Masayuki; Maniwa, Takashi; Hanabusa, Mitsugu

    1998-05-01

    Iron thin films were prepared by pulsed laser deposition using cast iron as a target. The films deposited by using a 1.064 ?m Nd:YAG laser on silicon wafer corroded easily in a 0.001 mol/l NaCl aqueous solution, as seen by a change of the surface color. In a similar test, no visible change of the color was observed for the film deposited by using the 532 nm second harmonics from the Nd:YAG laser. However, the inspection under an optical microscope revealed localized corrosion around the particles mixed into the iron film.

  4. Probabilistic risk analysis of corrosion associated failures in cast iron water mains

    This paper proposes a method using probabilistic risk analysis for application to corrosion associated failures in grey cast iron water mains. External corrosion reduces the capacity of the pipeline to resist stresses. When external stresses exceed the residual ultimate strength, pipe breakage becomes imminent, and the overall reliability of a water distribution network is reduced. Modelling stresses and external corrosion acting on a pipe involves uncertainties inherent in the mechanistic/statistical models and their input parameters. Monte Carlo (MC) simulations were used to perform the probabilistic analysis. The reduction in the factor of safety (FOS) of water mains over time was computed, with a failure defined as a situation in which FOS becomes smaller than 1. The MC simulations yielded an empirical probability density function of time to failure, to which a lognormal distribution was fitted leading to the derivation of a failure hazard function. A sensitivity analysis revealed that the contribution of corrosion parameters to the variability of time to failure was more significant than the combined contributions of all other parameters. Areas where more research is needed are identified

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

    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

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

    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.

  7. Interfacial morphology and corrosion resistance of Fe-B cast steel containing chromium and nickel in liquid zinc

    Highlights: ? Fe-B steels containing Cr and Ni exhibit the best corrosion resistance in liquid zinc. ? Surface layers show gamma-Fe3Zn10, delta-FeZn10, zeta-FeZn13 and eta-Zn. ? Cr and Ni can enrich at the interface during the corrosion process. ? Corrosion processes include leaching, formation of compounds and spalling of borides. - Abstract: The interfacial morphology and corrosion resistance of low carbon Fe-B cast steels in zinc bath at 520 deg. C were investigated. The results show Fe-B cast steel containing high Cr and Ni exhibits the best corrosion resistance to liquid zinc. The corrosion layers are composed of ?-Fe3Zn10, ?-FeZn10, ?-FeZn13 and ?-Zn. The corrosion behaviour of Fe-B cast steels includes the following processes: the preferential leach and dissolution of Cr and Ni, the formation of Fe-Zn compounds controlled by zinc atom diffusion, and the spalling of borides without the supporting role of ?-(Fe, Cr) matrix corroded by liquid zinc.

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

    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.

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

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

  10. The influence of environment on corrosion of cast iron and carbon steel representing samples of outdoor metal technical heritage

    Strzelec, M.; Marczak, J.; Skrzeczanowski, W.; Zatorska, A.; Sarzynski, A.; Czyz, K.; Zasada, D.

    2015-06-01

    This paper presents the results of annual measurements of the corrosion progress at test samples of cast iron and carbon steel placed in different natural environments. Comparative tests were performed in two outdoor stations, one at the Railway Museum in central Warsaw and one at the location of a Railway Museum in the small town of Sochaczew, 50 km west of Warsaw. The influence of surface roughness on the development of corrosion was determined by two kinds of treatment of all sample surfaces - metal brush or grinding. Stratigraphy and composition of corrosion products in quarterly periods were analyzed with laser-induced breakdown spectroscopy (LIBS) and Raman laser spectroscopy. Comparative tests were performed using a scanning electron microscopy (SEM) system equipped with energy dispersive spectrometer (EDS) and micro-chemical analytical methods. The corrosion layers on carbon steel have proven to be thicker on average than on cast iron, and thicker on the brushed parts of both materials. Furthermore, a thicker corrosion layer was found on the cast iron test samples exposed in Sochaczew than in Warsaw. Different iron oxides, namely lepidocrocite, goethite, hematite and magnetite were identified in the surface Raman spectra of corrosion layers, the last compound only in the sample from Sochaczew. SEM EDS measurements of surface elemental concentrations showed a higher concentration of sulfur in all samples from Sochaczew. Registered LIBS spectra have been additionally analyzed with statistical approach, using Factorial Analysis (FA). Results generally confirmed conclusions drawn from SEM/Raman/LIBS results.

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

    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 processing to eliminate excessive retained austenite was found to be most influential in terms of high strengths. It was also found that cooling below 0°C provided the best combination of strength and toughness, with the specific strength of the material exceeding that of cast Ti-6Al-4V material. Fractography studies suggest that titanium carbonitride and titanium carbon-nitride-sulfide inclusions limit the toughness of cast materials due to long exposures to ideal growth conditions during initial cooling. OIM studies also suggest that the retained austenite in properly processed 11-11PH alloy takes on an interlath structure, which likely contributes to toughness of the alloy, even at high-strength, peak aged conditions. Yield strengths approaching 235 ksi (1620 MPa) were achieved during initial heat treatment trials. It is expected that further improvements in properties can be achieved with continued improvement of processing for this new cast alloy system.

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

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

    2015-01-01

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

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

    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

  14. The microvasculature of the corpus luteum in pregnant rabbit. A scanning electron microscopy study of corrosion casts.

    Macchiarelli, G; Nottola, S A; Picucci, K; Stallone, T; Motta, P M

    1998-01-01

    The vascular network of pregnant rabbit ovaries was studied by means of scanning electron microscopy (SEM) of corrosion casts, in order to evaluate the morphofunctional changes of the microcirculation of corpus luteum (CL). Pregnant rabbit ovary showed an overwhelming vascularization. Ovarian hilus displayed an increase in the arterial spirallisation. The arterial spiral pattern was present along the entire vessel course, up to CL tissues. The CL of pregnancy was supplied by wide vascular plexuses (2-5 plexuses were found in each pregnant ovary) whose major axis was about 2 mm. Luteal capillaries showed a tortuous course and were arranged in a three-dimensional, wide and rounded-meshed network. Postcapillary venoconstrictions were present. The venous drainage appeared more developed then the arterial supply. Tight artero-venous contacts in hilar, juxtamedullar and medullar regions of the ovary were observed. These results clearly show that the morphofunctional expression of CL of pregnancy is greatly dependent on its hemodynamic control. In particular, the increase of spirallisation exhibited by the arteries during pregnancy is likely to be considered a significant functional change. The spirallisation likely is a device for reducing the blood pressure through the CL. The artero-venous contacts, also previously described in hCG stimulated (pseudopregnant) ovaries, may support a counter-current like system that may allow a veno-arterial exchange of small molecules through the wall of the facing vessels. In addition, in 10-day pregnant rabbit CL the consolidation of a well-developed capillary network was revealed, which is a sign that the CL of pregnancy reached the full morphofunctional maturation. Furthermore, the CL of 10-day pregnant rabbit did not present significant capillary permeabilization and dilation or angiogenic processes, aspects that were previously found in stimulated periovulatory ovaries. Indeed, changes of the arterial supply and venous drainage of the CL of pregnancy were demonstrated. This suggests that the control of the blood flow through the CL of pregnancy may be transferred from the local capillary microcirculation to the regional artero/venous circulation. This may be probably related to the significant increase of the ovarian blood flow necessary for the maintenance of CL endocrine functions during pregnancy. PMID:11315950

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

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

  16. Cast

    Ohtsuka, Toshihisa; Takao-Rikitsu, Etsuko; Inoue, Eiji; Inoue, Marie; Takeuchi, Masakazu; Matsubara, Kaho; Deguchi-Tawarada, Maki; Satoh, Keiko; MORIMOTO, KOJI; NAKANISHI, Hiroyuki; Takai, Yoshimi

    2002-01-01

    The cytomatrix at the active zone (CAZ) has been implicated in defining the site of Ca2+-dependent exocytosis of neurotransmitter. We have identified here a novel CAZ protein of ∼120 kD from rat brain and named it CAST (CAZ-associated structural protein). CAST had no transmembrane segment, but had four coiled-coil domains and a putative COOH-terminal consensus motif for binding to PDZ domains. CAST was localized at the CAZ of conventional synapses of mouse brain. CAST bound directly RIM1 and ...

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

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

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

    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

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

    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.

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

    Krajewski, Katherine Mary

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

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

    Charlot, L.A.; Westerman, R.E.

    1981-07-01

    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.

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

    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

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

    Rajeswari, Velayutham [Department of Chemistry, Periyar University, Salem 636011 (India); Kesavan, Devarayan [Department of Chemistry, Dhirajlal Gandhi College of Technology, Salem 636309 (India); Gopiraman, Mayakrishnan [Department of Chemistry, National Institute of Technology, Tiruchirappalli 620015 (India); Viswanathamurthi, Periasamy, E-mail: viswanathamurthi72@gmail.com [Department of Chemistry, Periyar University, Salem 636011 (India); Poonkuzhali, Kaliyaperumal; Palvannan, Thayumanavan [Department of Bio-Chemistry, Periyar University, Salem 636011 (India)

    2014-09-30

    Graphical abstract: - Highlights: • Eleusine aegyptiaca and Croton rottleri are commonly available, less-toxic and eco-friendly inhibitors for cast iron corrosion. • The active constituents present in extracts adsorbed on the iron surface to inhibit the acidic corrosion. • The higher values of E{sub a} and ΔH{sup *} point out the higher inhibition efficiency noticed for the inhibitors. • Weight loss methods at various temperature and spectral data provides evidence for adsorption mechanism of inhibitors. - Abstract: 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.

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

    Graphical abstract: - Highlights: Eleusine aegyptiaca and Croton rottleri are commonly available, less-toxic and eco-friendly inhibitors for cast iron corrosion. The active constituents present in extracts adsorbed on the iron surface to inhibit the acidic corrosion. The higher values of Ea and ?H* point out the higher inhibition efficiency noticed for the inhibitors. Weight loss methods at various temperature and spectral data provides evidence for adsorption mechanism of inhibitors. - Abstract: 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, UVvis, Wide-angle X-ray diffraction and SEM methods

  5. Cast

    Ohtsuka, Toshihisa; Takao-Rikitsu, Etsuko; Inoue, Eiji; Inoue, Marie; Takeuchi, Masakazu; Matsubara, Kaho; Deguchi-Tawarada, Maki; Satoh, Keiko; Morimoto, Koji; Nakanishi, Hiroyuki; Takai, Yoshimi

    2002-01-01

    The cytomatrix at the active zone (CAZ) has been implicated in defining the site of Ca2+-dependent exocytosis of neurotransmitter. We have identified here a novel CAZ protein of ∼120 kD from rat brain and named it CAST (CAZ-associated structural protein). CAST had no transmembrane segment, but had four coiled-coil domains and a putative COOH-terminal consensus motif for binding to PDZ domains. CAST was localized at the CAZ of conventional synapses of mouse brain. CAST bound directly RIM1 and indirectly Munc13-1, presumably through RIM1, forming a ternary complex. RIM1 and Munc13-1 are CAZ proteins implicated in Ca2+-dependent exocytosis of neurotansmitters. Bassoon, another CAZ protein, was also associated with this ternary complex. These results suggest that a network of protein–protein interactions among the CAZ proteins exists at the CAZ. At the early stages of synapse formation, CAST was expressed and partly colocalized with bassoon in the axon shaft and the growth cone. The vesicles immunoisolated by antibassoon antibody–coupled beads contained not only bassoon but also CAST and RIM1. These results suggest that these CAZ proteins are at least partly transported on the same vesicles during synapse formation. PMID:12163476

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

    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

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

    The novel interpenetrating (HA + β-TCP)/MgCa composites were fabricated by infiltrating MgCa alloy into porous HA + β-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 + β-TCP scaffolds was very well. The ultimate compressive strength of the composites was about 500–1000 fold higher than that of the original porous scaffolds, and it still retained quarter-half of the strength of the bulk MgCa alloy. The electrochemical and immersion tests indicated that the corrosion resistance of the composites was better than that of the MgCa matrix alloy, and the corrosion products of the composite surface were mainly Mg(OH)2, HA and Ca3(PO4)2. Meanwhile, the mechanical and corrosive properties of the (HA + β-TCP)/MgCa composites were adjustable by the choice of HA content. - Highlights: • The composites were fabricated by infiltrating MgCa alloy into porous HA + β-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

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

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

    2014-09-01

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

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

    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.

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

    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.

  11. Moessbauer study of the composition and corrosion behaviour of electrodeposited and cast brass containing 1-4 m% tin

    Moessbauer measurements on electrodeposited and cast brass containing 1-4 m% tin were carried out using conversion electron detector. It was found that the tin formed phases with copper but not with zinc. The identified phases were β, γ, epsilon and eta and their ratio depended on the tin concentration and on the preparation process of the brass. The corrosion behaviour of the samples was also studied. (author)

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

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

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

    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.

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

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

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

    Highlights: • The novel co-continuous β-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 β-TCP/MgCa composite was fabricated by infiltrating MgCa alloy into porous β-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 β-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 β-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

  16. High temperature response of selected microstructures in Fe-Mn-Cr-Cu corrosion resistant alloy cast irons

    Kumar, Vinod

    2003-08-01

    High temperature response was determined by thermo-gravimetric method for the microstructures in the (1) as-cast, (2) 950 C, 10 h, air cooled, and (3) 1050 C, 10 h, air cooled conditions for four newly designed cast irons designated as B1 (6Mn-5Cr-1.5Cu), B2 (7.5Mn-5Cr-1.5Cu), B3 (6Mn-5Cr-3.0Cu), and B4 (7.5Mn-5Cr-3.0Cu) and intended to resist aqueous corrosion under marine conditions. The current study was undertaken as corrosion resistant compositions may have potential applications as high temperature materials. It was observed that while the as-cast microstructure was useful only up to 600 C, the above mentioned heat treatments raised the useful temperature limit of application to 800 C. The relative performance of the alloys was a function of the austenite volume fraction and its stability, morphology, and stability of the second phase and the proneness of the alloys to carbide transformation. The data thus obtained is of considerable interest for alloy design in the future as it lays down guidelines for developing modified compositions exhibiting excellent high temperature response.

  17. In-situ corrosion studies on cast steel for a high-level waste packaging in a rock salt repository

    This paper reports on in-situ experiment conducted in the Asse salt mine in which the influence of selected characteristics (welding, shape) of containers on the corrosion behavior of cast steel was studied. The material was tested in NaCl brine which might intrude into an HLW borehole in an accident scenario. For this, an electron beam welded cast-steel tube was stored for 18 months in a 2-m deep heated borehole and the annular gap between the tube and the borehole wall was filled with saturated NaCl brine. The vertical temperature profile in the borehole was in the range from 900C to 2000C; the maximum temperature occurred in the center of the heated zone and the minimum temperature in the upper parts of tube

  18. Effects of silicon on the oxidation, hot-corrosion, and mechanical behavior of two cast nickel-base superalloys

    Miner, R. V., Jr.

    1977-01-01

    Cast specimens of nickel-base superalloys 713C and Mar-M200 with nominal additions of 0, 0.5, and 1 wt% Si were evaluated for oxidation and corrosion resistance, tensile and stress-rupture properties, microstructure, and phase relations. Results are compared with those of an earlier study of the effects of Si in B-1900. Si had similar effects on all three superalloys. It improves oxidation resistance but the improvement in 713C and Mar-M200 was considerably less than in B-1900. Hot-corrosion resistance is also improved somewhat. Si is, however, detrimental to mechanical properties, in particular, rupture strength and tensile ductility. Si has two obvious microstructural effects. It increases the amount of gamma-prime precipitated in eutectic nodules and promotes a Mo(Ni,Si)2 Laves phase in the alloys containing Mo. These microstructural effects do not appear responsible for the degradation of mechanical properties, however.

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

    R. Zapa?a

    2009-07-01

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

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

    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.

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

    Jurkovikj Dragica M.

    2013-01-01

    Full Text Available On the 20 post-autopsy adult isolated liver specimens of patients of both sexes (17 male and 3female aged 2988, the injection-corrosion method was used. Colored acrylate was injected into the biliary system, and uncolored acrylate into the portal vein. A total of 17 acrylate casts were of proper quality.Within the 9 portal segments, both the anatomical determination and quantity and the mode of confluence of intrahepatic bile ducts were established. Different modes of biliary tract confluence up to the sectors and hepatics were found. Besides the most frequent findings of conventionally confluence bile ducts, there were aberrant modalities of biliary drainage in eight cases. Among them 5 cases had confluence of posterior and anterior sector ducts in the left hepatic duct and 1 case had confluence at first of anterior and then posterior sector ducts in the left hepatic duct. Also, extrahilar connection of the right posterior with left lateral into common hepatic duct, where the latter entered themedial and anterior sectors ducts in1 case was found. There was a subsequent confluence of ducts from the 8th and 5th segments in 1 case, and from the lateral andmedial sectorswith or without caudate lobe in 3 cases. A common (4 or separate (2 confluence of left and right portions ducts in the left drainage system were in 6 cases, whereas in both, the left and right drainage system in 7 cases was found. Rare, there wasan aberrant single channel from the right portion in 1 case, as well as the presence and biliary drainage only of the left portion of 1st segment was found. Segment 9 bile ducts drained all three subsegments (b, c and d in 10 cases, and only two (c and d in 3 cases, as well as only two (c and b of present three subsegments in 3 cases. Also, there was even one case with present 9d subsegment and without 9th segment duct. Those modalities are of interest in an applying and accurate interpretation and performance of diagnostic and interventional procedures, as well as in segmental, sectoral or hemihepatic resection in liver surgery.

  2. Analytical and electrochemical evaluation of the in vitro corrosion behavior of nickel-chrome and cobalt-chrome casting alloys for metal-ceramic restorations.

    Yfantis, Constaninos; Yfantis, Dimitrios; Anastassopoulou, Jane; Theophanides, Theophilos

    2007-03-01

    In this study we examined the hypothesis based on relevant literature survey that the in vitro corrosion behavior of a Cobalt-chrome dental casting alloy for metal-ceramic restorations is better than that of a Nickel-chrome dental casting alloy. The corrosion released metal ions were analysed by Inductively Coupled Plasma-Atomic Emission Spectroscopy. Moreover, the specimens were electrochemically tested by linear polarization. The statistical analysis of the results showed statistically significant differences in corrosion rates of Nickel-chrome alloy and Cobalt-chrome alloy calculated by analytical and electrochemical measurements. The hypothesis was confirmed and the results showed that the corrosion rates of the Cobalt-chrome alloy were lower than that of the Nickel-chrome alloy. PMID:17378457

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

    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 microscopy and sweep electronics (CW)

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

    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.

  5. Corrosion of low-carbon cast steel in concentrated synthetic groundwater at 80 to 150 C

    Corrosion properties of American Society for Testing and Materials (ASTM) A216-Grade WCA low-carbon steel were evaluated in concentrated synthetic groundwater at 80 to 150 C. The evaluation provides information on the use of the steel as a container material in the proposed Yucca Mountain high-level waste repository. Uniform corrosion rates measured over 4 months ranged from 10 to 40 microm/year, in initially aerated static solutions under gamma irradiation at 1.3 x 106 rad/h. Irradiation effects on uniform corrosion rates were not discernible after 4 months. Pitting corrosion was also found, but the pitting factor was small. Microstructural effects on corrosion were not significant. During corrosion under irradiation, there was an indication of a large amount of hydrogen absorption in the steel. Constant extension rate tests showed evidence for environmental assisted cracking under free corrosion conditions, and strong evidence of hydrogen embrittlement and moisture-induced ductility loss. The use of the test results in support of the Yucca Mountain project is discussed

  6. Corrosion rate of unalloyed steels and cast irons in reducing granitic groundwaters and chloride solutions

    Measurements of the corrosion rate of unalloyed steel have been made under conditions representative for repositories in the granitic bedrock of Northern Switzerland using two independent methods: (1) immersion tests in two representative groundwaters, with and without bentonite; (2) hydrogen evolution measurements in these groundwaters. The immersion tests were carried out at 800C and 1400C. In both cases the corrosion rate was higher than 50 ?m/a as determined at the end of the first observation period of about 500 h. Corrosion rates of under 10 ?m/a were estimated after the first 500 h. The corrosion rates were similar in both groundwaters with mineralizations of approx. 3 g/l and 14 g/l respectively, and were generally higher at 800C than at 1400C. The hydrogen evolution measurements allow an hourly determination of the corrosion rate, with a sensitivity expressed as a corrosion rate of better than 0.1 ?m/a. The results generally confirm the observation made in the immersion testing; high corrosion rates were observed over the first few days but then decreased to values well below 10 ?m/a. The steady state corrosion rates measured were 1.1 ?m/a, 6.5 ?m/a, and 2.5 ?m/a at 250C, 500C, and 800C respectively in the water with the higher mineralization. The inverse temperature effect on corrosion rate above 500C is attributed to a change in the nature of the passive film at higher temperatures

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

    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

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

    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

  9. Corrosion

    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)

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

    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.

    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. A Study of Variations of the Branching Patterns of right Upper Lobar Bronchus by Corrosive Cast Method

    SV Solanki

    2015-06-01

    Full Text Available Introduction: Respiratory system is the basic prerequisite for living organisms. So precise knowledge of normal anatomy and various dimensions of human respiratory tract is inevitable. The right upper lobe bronchus is prevailingly trifurcates into apical, anterior and posterior segmental bronchi. Material and Methods: The present study was done on 28 tracheo-bronchial casts prepared by corrosive cast method in the anatomy department of B. J. medical college of Ahmedabad, Gujarat, India from 2011 to 2013. Result and Observation: In 16 specimens (57% normal trifurcate branching pattern was seen in right upper lobar bronchus. Most common variation observed was bifurcate pattern in right upper lobar bronchus in 36% of specimens. In 7% specimens quadrivial pattern was seen in right upper lobar bronchus in which it divided into four bronchi. Conclusion: The knowledge of anatomy and variation in branching pattern of the tracheo-bronchial tree enables the physicians to recognize clinical picture and pathology of human lungs, as well as the application of therapeutic and diagnostic methods like tracheal intubation, bronchoscopy, bronchography and postural drainage etc.

  13. Effects of graphite nodule size on corrosion resistance of borided spheroidal graphite cast iron; Hoka shorishita kyujo kokuen chutetsu no taishokusei ni oyobosu kokuen ryukei no eikyo

    Ikenaga, A.; Kawamoto, M.; Nitta, Y. [University of Osaka Prefecture, Osaka (Japan). Faculty of Engineering; Sato, Y. [Osaka Prefectural Industrial Technology Research Institute, Osaka (Japan); Araki, H. [Industrial Research Canter of Nara Prefecture, Nara (Japan)

    1996-03-25

    In order to learn corrosion resistance of borided spheroidal graphite cast iron to such non-oxidizing aqueous solutions as hydrochloric acid and sulfuric acid, anodic polarization curves on test specimen surface were measured to investigate their corrosion behavior. Tested materials used included three kinds of graphite with different grain sizes and counts. Boronization was performed in a flow layer at 1173 K by using a commercially available treatment agent (using SiC for granulating aggregate, comprising mainly B4C and KBF4), followed by oil quenching. The surface of the boronized spheroidal graphite cast iron had better corrosion resistance as a result of formation of FeB and Fe2B boronized layers than untreated materials and oil quenched materials (not boronized, but oil-quenched after austenitization). The longer the boronization time, the thicker the boronized layer, resulting in increase of FeB and improvement in corrosion resistance. Boronized materials with larger graphite grain sizes were found to have better corrosion resistance. This is because the larger the graphite grain sizes, the thicker the highly corrosion resistant boronized layer, and the graphite particle boundary line from which Fe dissolves preferentially becomes shorter. 7 refs., 11 figs., 2 tabs.

  14. MRI-compatible Nb-60Ta-2Zr alloy for vascular stents: Electrochemical corrosion behavior in simulated plasma solution.

    Li, Hui-Zhe; Zhao, Xu; Xu, Jian

    2015-11-01

    Using revised simulated body fluid (r-SBF), the electrochemical corrosion behavior of an Nb-60Ta-2Zr alloy for MRI compatible vascular stents was characterized in vitro. As indicated by XPS analysis, the surface passive oxide film of approximately 1.3nm thickness was identified as a mixture of Nb2O5, Ta2O5 and ZrO2 after immersion in the r-SBF. The Nb-60Ta-2Zr alloy manifests a low corrosion rate and high polarization resistance similar to pure Nb and Ta, as shown by the potentiodynamic polarization curves and EIS. Unlike 316L stainless steel and the L605 Co-Cr alloy, no localized corrosion has been detected. Semiconducting property of passive film on the Nb-60Ta-2Zr alloy was identified as the n-type, with growth mechanism of high-field controlled growth. The excellent corrosion resistance in simulated human blood enviroment renders the Nb-60Ta-2Zr alloy promising as stent candidate material. PMID:26249582

  15. The Structure and Properties of Inductively Coupled Plasma Assisted Magnetron Sputtered Nanocrystalline CrN Coatings in Corrosion Protective Die Casting Molds.

    Chun, Sung-Yong

    2015-07-01

    Chromium nitride coatings for the surface modified die casting molds with various ICP powers have been prepared using ICP assisted magnetron sputtering. The applied ICP power was varied from 0 to 300 W. The deposited coatings were characterized post-deposition using X-ray diffractometry (XRD) and atomic force microscopy (AFM). Single CrN phased coatings with nano-grain sized (< 20 nm) were identified. The corrosion resistance and hardness of each coating were evaluated from potentiost at and nanoindentator. Superior corrosion protective coatings in excess of 20 GPa were deposited with assistance of ICP plasma during sputtering. PMID:26373141

  16. Structure and Properties of Graphite Microspheres Containing Ferromagnetic Metal Prepared by Acid Corrosion of Cast Iron

    Wang, Y.; An, C. G.; He, Y. Z.; Li, H.

    2014-12-01

    Graphite microspheres containing ferromagnetic metal were prepared by acid corrosion of Fe-C alloys, and their microstructure and magnetic properties were also investigated. Our result showed that graphite microsphere is magnetic whose coercivity was 201.12 Oe at room temperature. The XPS result showed that no magnetic elements were detected on the surface of graphite spheres, suggesting that the magnetism of the graphite microsphere comes from the ferromagnetic metals encapsulated in graphite sphere and not from the graphite itself. The possible formation mechanism of graphite sphere is that the magnetic particles are trapped by tortuous graphene and attached shell by shell to form a sphere.

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

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

  18. Three-dimensional organization of lymphatics in the dog stomach: a scanning electron microscopic study of corrosion casts.

    Sugito, M; Araki, K; Ogata, T

    1996-03-01

    The three-dimensional organization of the lymphatics in the dog stomach was studied by scanning electron microscopy of corrosion casts, which were made by direct parenchymal injection of low-viscosity Mercox-resin into the mucosa and the muscular layers. Although the organization of lymphatics in the stomach has been studied by a variety of methods, the origin of the lymphatics and their connection in each layer has not been clearly defined. In this study, using dog stomach because of its structural similarity to the human stomach, we defined the lymphatic structure in all gastric layers, with lymphatics absent in the upper two-thirds of the lamina propria mucosae. They were first encountered at the deepest level of the lamina propria, immediately above the lamina muscularis mucosae. These lymphatics were composed of single-layered irregular meshes. Slender lymphatics arising from this network passed through the lamina muscular is mucosae and drained into the lymphatic plexus, which was composed of thicker lymphatics at the uppermost layer of the submucosa. Lymphatic valves were frequently seen in this plexus. From this plexus, slender connecting lymphatics with valves extended straight downward without lateral communications and drained into the lymphatic plexus at the deepest layer of the submucosa. This latter plexus, composed of large-caliber lymphatics, issued flattened lymphatics which formed a three-dimensional network in the muscular layer. The subserosal lymphatics were composed of thick lymphatics with tortuous courses and drained into the efferent lymphatics. PMID:8727364

  19. Dominncia coronariana em coraes humanos em moldes por corroso / Coronary dominance patterns in the human heart investigated by corrosion casting

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

    2009-12-01

    Full Text Available OBJETIVO: Esse trabalho tem como objetivo analisar os padres de dominncia circulatria de coraes humanos, o nmero de ramos que a artria coronria direita fornece ao ventrculo esquerdo, o nmero de ramos que a artria coronria esquerda fornece ao direito e a presena de anastomoses intercoron [...] arianas, com sua localizao e frequncia. MTODOS: Foram produzidos 25 moldes de coraes submetidos instilao de acrlico colorido e posterior corroso com cido clordrico, no Laboratrio de Cirurgia Experimental da FURB. Peas com leses e cicatrizes no foram usadas. RESULTADOS: Os coraes pertenciam a indivduos de ambos os sexos, sendo 17 (68%) de indivduos do sexo masculino, com idade mdia de 40,2 anos (15 a 70 anos). A dominncia direita ocorreu em 18 (72%) peas, com 1, 2, 3 e 4 ramos em 2, 14, 2 e 1 moldes, respectivamente; a dominncia esquerda foi observada em 5 (20%) casos, com 1 ramo em 4 moldes e 2 em 1 molde; e a dominncia balanceada foi verificada em 2 (8%) moldes. Houve diferena significativa entre a dominncia direita e esquerda (? > 5%), direita e balanceada (? > 5%) e sem significncia entre esquerda e balanceada (? Abstract in english OBJECTIVES: The aim of this work was to analyze the dominance patterns of the circulation of the human heart, the number of branches from the right coronary artery to the left ventricle, the number of branches from the left coronary artery to the right ventricle and the frequency and location of int [...] ercoronary anastomoses. METHODS: Casts were made of 25 hearts by the injection of colored acrylic resin and subsequent corrosion using hydrochloric acid at the experimental surgery laboratory of Furb. Specimens with lesions or scars were discarded. RESULTS: The hearts, from both men (17 - 68%) and women (8 - 32%), had a mean age of 40.2 (15 to 70) years-old. Right dominance occurred in 18 (72%) subjects, with 1, 2, 3 and 4 branches leading to the left ventricle in 2, 14, 2 and 2 casts, respectively. Left dominance occurred in 5 (20%) with 1 branch leading to the right ventricle in 4 molds and 2 in one. Balanced circulation was observed in two molds (8%). There were significant differences between right and left dominance (? > 5%) and between right dominance and balanced circulation (? > 5%), however the same was not true between left dominance and balanced circulation (?

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

    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

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

    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 α-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 α-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

  2. 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

    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)

  3. Evaluation of Neutron Elastic Scatter (NES) technique for detection of graphitic corrosion in gas cast iron pipe. Final report, March 1996-April 1997

    Charatis, G.; Hugg, E.; McEllistrem, M.

    1997-04-01

    PENETRON, Inc., in two phases, demonstrated the effectiveness of its Neutron elastic Scatter (NES) techniques in detecting the change in the carbon weight percentage (CWt%) as a measure of corrosion in gray cast iron pipe. In Phase I, experiments were performed with synthetic standards supplied by IIT Research Institute (IITRI) to test the applicability of the NES techniques. Irradiation experiments performed at the University of Kentucky showed that CWt% could be detected, ranging from 1.6% to 13%, within an uncertainty of around 4%. In Phase II, experiments were performed on seven (7) corroded pipe sections supplied by MichCon. Tests were made on pipe sliced lengthwise into quarter sections, and in re-assembled whole pipe sections. X-ray films of the quarter sections indicated probable areas of corrosion for each quarter section.

  4. Microstructure And Erosion-Corrosion Behaviour Of As-Cast High Chromium White Irons Containing Molybdenum In Aqueous Sulfuric-Acid Slurry

    Imurai S.

    2015-06-01

    Full Text Available Microstructure and erosion-corrosion behaviour of as-cast high chromium white irons containing molybdenum in aqueous sulfuric-acid slurry was studied. The experimental irons contained 28 wt.%Cr with a Cr:C ratio of about 10 and up to 10 wt.%Mo. The irons with up to 6 wt.%Mo are hypoeutectic, whereas the iron with 10 wt.%Mo becomes eutectic/peritectic. Mo addition promotes formation of M23C6 and M6C, instead of typical M7C3. Erosion-corrosion testing was performed in aqueous sulfuric-acid slurry containing alumina particles. The hypoeutectic Fe-28Cr-2.7C-1Mo with mainly M7C3 and the eutectic/peritectic Fe-28Cr-2.6C-10Mo showed reduced wear rates of about 30% and 7% of that of the reference iron without Mo addition, respectively. The reduction of the carbide-matrix hardness difference, the increase of corrosion resistance of the matrices, and the increase of macro-hardness are determining factors for the improvement of erosion-corrosion resistance of the irons.

  5. Effects Of T6 Heat Treatment With Double Solution Treatment On Microstructure, Hardness And Corrosion Resistance Of Cast Al-Si-Cu Alloy

    Wiengmoon A.

    2015-06-01

    Full Text Available Effects of T6 heat treatment with double solution treatment on microstructure, hardness and corrosion resistance of a cast A319 (Al-4.93wt%Si-3.47wt%Cu alloy were investigated. The T6 heat treatment comprised of the first solution treatment at 500±5°C for 8 h, the second solution treatment in the temperature range of 510 to 530±5°C for 2 h followed by water quenching (80°C, and artificial aging at 170°C for 24 h followed by water quenching (80°C. Microstructure of the alloy was studied by optical microscopy and electron microscopy, Rockwell hardness was measured, and corrosion resistance in 0.1 M NaCl aqueous solution was determined by a potentiodynamic technique. The results revealed that the T6 heat treatment with double solution treatment led to an improvement in corrosion resistance and comparable macrohardness as compared to those obtained from the case of single solution treatment. The second solution treatment at 520°C is the optimum leading to relatively low corrosion current density without substantial drawbacks on breakdown potential or the width of passive range.

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

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

    2011-07-01

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

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

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

  8. 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

    Z, A.; Samur, R.; H. Mindivan; Demir, A; Sagiroglu, S.; A. K. Yakut

    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. ...

  9. Architectural optimization of an epoxy-based hybrid solgel coating for the corrosion protection of a cast Elektron21 magnesium alloy

    An epoxy-based hybrid solgel 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 solgel 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 solgel 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.

  10. Architectural optimization of an epoxy-based hybrid solgel coating for the corrosion protection of a cast Elektron21 magnesium alloy

    Murillo-Gutirrez, N.V., E-mail: murillo@chimie.ups-tlse.fr [Universit de Toulouse UPS-INP-CNRS, Institut Carnot CIRIMAT, Toulouse (France); Ansart, F.; Bonino, J-P. [Universit 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 solgel 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 solgel 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 solgel 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.

  11. 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

    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.

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

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

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

    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)

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

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

  15. Effects of long-term thermal aging on the stress corrosion cracking behavior of cast austenitic stainless steels in simulated PWR primary water

    Li, Shilei; Wang, Yanli; Wang, Hui; Xin, Changsheng; Wang, Xitao

    2016-02-01

    The stress corrosion cracking (SCC) behavior of cast austenitic stainless steels of unaged and thermally aged at 400C for as long as 20,000h were studied by using a slow strain rate testing (SSRT) system. Spinodal decomposition in ferrite during thermal aging leads to hardening in ferrite and embrittlement of the SSRT specimen. Plastic deformation and thermal aging degree have a great influence on the oxidation rate of the studied material in simulated PWR primary water environments. In the SCC regions of the aged SSRT specimen, the surface cracks, formed by the brittle fracture of ferrite phases, are the possible locations for SCC. In the non-SCC regions, brittle fracture of ferrite phases also occurs because of the effect of thermal aging embrittlement.

  16. Stress corrosion cracking of gas-tungsten arc welds in continuous-cast AZ31 Mg alloy sheet

    AZ31 Mg alloy sheet was welded using a gas-tungsten arc (GTA) process over inserts containing 2.3-9.3 wt.% Al. The welded specimens were susceptible to SCC in distilled water, with susceptibility increasing with decreasing weld metal Al (or ? particle) concentration. Primary stress corrosion cracks initiated at the weld metal-HAZ interface by stress-assisted localised dissolution and propagated through the weld and base metals by transgranular and intergranular H-assisted fracture (TG-HAF and IG-HAF) respectively. The IG fracture mode may be intrinsic to the texture imparted upon the base metal by rolling. The increase in SCC susceptibility with decreasing weld metal Al concentration is contrary to the purported roles of ? particles in promoting localised corrosion and as crack nucleation sites, but corresponds with increases in weld - base metal galvanic current density and weld metal localised corrosion susceptibility.

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

    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

  18. Erosion-corrosion and surface protection of A356 Al/ZrO{sub 2} composites produced by vortex and squeeze casting

    El-Khair, M.T. Abou [Central Metallurgical Research and Development Institute, CMRDI, P.O. 87 Hellwan, Cairo (Egypt); Aal, A. Abdel [Central Metallurgical Research and Development Institute, CMRDI, P.O. 87 Hellwan, Cairo (Egypt)], E-mail: foralsayed@yahoo.com

    2007-04-25

    Erosive-corrosive wear behavior of Al-Si-Mg (A356 Al) alloy and its composite reinforced by ZrO{sub 2} 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-ZrO{sub 2}.

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

    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 ...

  20. CORROSION RESISTANCE OF PEARLITIC AND BAINITIC CAST IRON IN A SYNTHETIC SOLUTION OF CONDENSED GAS FROM COMBUSTION

    Sandra Matos Cordeiro Costa; Emerson Igor Reginaldo; Isolda Costa

    2015-01-01

    The corrosion of engine components of the combustion chamber is usually related to the formation of acids such as sulfuric and nitric. These acids are generated by the condensation of combustion gases that usually occur in vehicle exhaust systems. However, with the development of new technologies to reduce emissions, condensation is also being promoted in vehicle combustion chambers. This fact is associated with high exhaust gas recirculation rates, known as EGR (English term for ...

  1. Human kidney glomeruli, with special reference to those in the aged person: scanning electron microscopic study of microvascular corrosion casts.

    Hitomi,Kusukuma; Murakami,Takuro; Kaneshige,Tetsuji

    1987-01-01

    Blood vascular beds of fetal, adult and aged human kidneys were reproduced with methyl methacrylate and observed with a scanning electron microscope. The kidney glomeruli, including those from the fetal kidneys, had anastomosing capillaries. The glomeruli in the kidneys of an aged person contained many more capillaries which were much more tortuous than those of the adult and fetal kidneys. Furthermore, it was observed that the glomeruli in the kidneys of the aged person usually received tort...

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

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

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

    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.

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

    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.

  5. Rapid vascular responses to anthrax lethal toxin in mice containing a segment of chromosome 11 from the CAST/Ei strain on a C57BL/6 genetic background.

    Weigel, Kelsey J; Rues, Laura; Doyle, Edward J; Buchheit, Cassandra L; Wood, John G; Gallagher, Ryan J; Kelly, Laura E; Radel, Jeffrey D; Bradley, Kenneth A; LeVine, Steven M

    2012-01-01

    Host allelic variation controls the response to B. anthracis and the disease course of anthrax. Mouse strains with macrophages that are responsive to anthrax lethal toxin (LT) show resistance to infection while mouse strains with LT non-responsive macrophages succumb more readily. B6.CAST.11M mice have a region of chromosome 11 from the CAST/Ei strain (a LT responsive strain) introgressed onto a LT non-responsive C57BL/6J genetic background. Previously, B6.CAST.11M mice were found to exhibit a rapid inflammatory reaction to LT termed the early response phenotype (ERP), and displayed greater resistance to B. anthracis infection compared to C57BL/6J mice. Several ERP features (e.g., bloat, hypothermia, labored breathing, dilated pinnae vessels) suggested vascular involvement. To test this, Evan's blue was used to assess vessel leakage and intravital microscopy was used to monitor microvascular blood flow. Increased vascular leakage was observed in lungs of B6.CAST.11M mice compared to C57BL/6J mice 1 hour after systemic administration of LT. Capillary blood flow was reduced in the small intestine mesentery without concomitant leukocyte emigration following systemic or topical application of LT, the latter suggesting a localized tissue mechanism in this response. Since LT activates the Nlrp1b inflammasome in B6.CAST.11M mice, the roles of inflammasome products, IL-1β and IL-18, were examined. Topical application to the mesentery of IL-1β but not IL-18 revealed pronounced slowing of blood flow in B6.CAST.11M mice that was not present in C57BL/6J mice. A neutralizing anti-IL-1β antibody suppressed the slowing of blood flow induced by LT, indicating a role for IL-1β in the response. Besides allelic differences controlling Nlrp1b inflammasome activation by LT observed previously, evidence presented here suggests that an additional genetic determinant(s) could regulate the vascular response to IL-1β. These results demonstrate that vessel leakage and alterations to blood flow are part of the rapid response in mice resistant to B. anthracis infection. PMID:22792226

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

    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

  7. Boride layer of austenitic spheroidal graphite cast iron boronized in fluidized bed and its corrosion and wear resistance; Ryudoso ni yoru austenite kyujo kokuen chutetsu no hoka shoriso oyobi sono taishoku, taimamosei

    Ueda, N.; Imizu, K.; Sone, T. [Osaka Prefectural Industrial Technology Research Institute, Osaka (Japan); Ikenaga, A.; Kawamoto, M. [University of Osaka Prefecture, Osaka (Japan). Faculty of Engineering

    1998-05-25

    Boronization using a fluidized bed was attempted on austenitic spheroidal graphite cast iron (ASGCI) to discuss its structure, hardness, wear and corrosion resistance. Boride layer derived from the fluidized bed showed hardness of about 1400 HK, and presented small protrusions between the base material and interface, which consisted mainly of FeB and Fe2B. In addition, Si and Ni in the boride layer were excluded, and concentrated in the form of stripes. Friction coefficient of the boronized material has no difference from that of untreated material, where variation is small, and stabilized slide characteristics were exhibited, when SUS304 material is used as the counterpart. When alumina is used as the counterpart, the friction coefficient was found reduced below that of the untreated material. With regard to wear resistance, specific wear amount decreased against any of the counterpart materials, and the boronization was an effective means to improve wear resistance of ASGCI. Measurements of natural potential revealed that boronization of ASGCI deteriorates corrosion resistance relative to 0.1N nitric acid and 3% salt solution, but improves the corrosion resistance relative to 0.1N hydrochloric acid and 0.1N sulfuric acid. 17 refs., 11 figs., 1 tab.

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

    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 austenitic phase at high temperature.

  9. 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

    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.

  10. Bimetallic layered castings alloy steel – grey cast iron

    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

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

    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.

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

    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.

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

    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.

  14. Corrosion of metallic materials. Dry corrosion, aqueous corrosion and corrosion by liquid metal, methods of protection

    This book is based on a course on materials given in an engineering school. The author first gives an overview of metallurgy issues: metallic materials (pure metals, metallic alloys), defects of crystal lattices (point defects, linear defects or dislocations), equilibrium diagrams, steels and cast, thermal processing of steels, stainless steels, aluminium and its alloys, copper and its alloys. The second part addresses the properties and characterization of surfaces and interfaces: singularity of a metal surface, surface energy of a metal, energy of grain boundaries, adsorption at a material surface, metal-electrolyte interface, surface oxide-electrolyte interface, techniques of surface analysis. The third chapter addresses the electrochemical aspects of corrosion: description of the corrosion phenomenon, free enthalpy of a compound and free enthalpy of a reaction, case of dry corrosion (thermodynamic aspect, Ellingham diagram, oxidation mechanisms, experimental study, macroscopic modelling), case of aqueous corrosion (electrochemical thermodynamics and kinetics, experimental determination of corrosion rate). The fourth part addresses the different forms of aqueous corrosion: generalized corrosion (atmospheric corrosion, mechanisms and tests), localized corrosion (galvanic, pitting, cracking, intergranular, erosion and cavitation), particular cases of stress cracking (stress corrosion, fatigue-corrosion, embrittlement by hydrogen), and bi-corrosion (of non alloyed steels, of stainless steels, and of aluminium and copper alloys). The sixth chapter addresses the struggle and the protection against aqueous corrosion: methods of prevention, scope of use of main alloys, geometry-based protection of pieces, use of corrosion inhibitors, use of organic or metallic coatings, electrochemical protection. The last chapter proposes an overview of corrosion types in industrial practices: in the automotive industry, in the oil industry, in the aircraft industry, and in the electronuclear industry

  15. Preferential dissolution behaviour in Ni–Cr dental cast alloy

    Viswanathan S Saji; Han Cheol Choe

    2010-08-01

    A Ni–Cr–Mo dental alloy was fabricated by three different casting methods, viz. centrifugal casting, high frequency induction casting and vacuum pressure casting. The dependence of cast microstructure on the electrochemical corrosion behaviour was investigated using potentiodynamic cyclic and potentiostatic polarization techniques, impedance spectroscopy and scanning electron microscopy. The experimental results were compared and discussed with those obtained for a Co–Cr–Mo counterpart. The results of the study showed that the variation in casting morphologies with casting methods has only marginal influence in the overall corrosion resistance of Ni–Cr and Co–Cr dental alloys. There was severe preferential dissolution of Ni rich, Cr and Mo depleted zones from the Ni–Cr–Mo alloy. The overall corrosion resistance property of the Co–Cr base alloy was better than that of the Ni–Cr base alloy.

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

    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 for the A2 phases and 3.67 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.

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

    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.

  18. Influence of hydronium, sulfate, chloride and other non-carbonate ions on hydrogen generation by anaerobic corrosion of granular cast iron.

    Ruhl, Aki S; Jekel, Martin

    2013-10-15

    Permeable reactive barriers are successfully applied for the removal of various contaminants. The concomitant reduction of hydrogen ions and the subsequent formation of hydrogen gas by anaerobic corrosion lead to decreased pore volume filled with water and thus residence times, so called gas clogging. Long term column experiments were conducted to elucidate the impact of ubiquitous water constituents on the formation of hydrogen gas and potential passivation due to corrosion products. The collected gas volumes revealed a relation to the hydronium concentration (pH) but were only slightly increased in the presence of chloride and sulfate and not significantly influenced in the presence of phosphate, silicate, humic acid and ammonium compared to deionized water. Significant gas volumes within the reactive filling were verified by gravimetry. The presence of nitrate completely eliminated hydrogen formation by competition for electrons. Solid phase analyses revealed that neither chloride nor sulfate was incorporated in corrosion products in concentrations above 0.1 weight percent, and they did not alter the formation of mainly magnetite in comparison to deionized water. PMID:23954066

  19. SPRAY CASTING

    SALAMCI, Elmas

    2010-01-01

    ABSTRACT This paper is designed to provide a basic review of spray casting. A brief overview of the historical development of spray  casting and the description of plant and equipment have been given. Following metallurgical characteristics of spray formed alloys, process parameters and solidification mechanism of spray deposition have been discussed in detail. Finally, microstructure and mechanical properties of the selected spray cast Al-Zn-Mg-Cu alloys have been presented and compared...

  20. Enrichment of Casting Surface in Founding Process

    J. Szajnar; P. Wrbel; T. Wrbel

    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 1801plate was placed on G25CrSiMnMoNi 4442,54 cast steel hammer of crusher. To investigations it was used light microscopy and scanning electron microscope. Microanalysis of chem...

  1. Corrosion study of iron-cobalt alloys for MRI-based propulsion embedded in untethered microdevices operating in the vascular network.

    Pouponneau, Pierre; Savadogo, Oumarou; Napporn, Teko; Yahia, L'hocine; Martel, Sylvain

    2010-04-01

    Our group have shown in an experiment performed in the carotid artery of a living swine that magnetic gradients generated by a clinical magnetic resonance imaging (MRI) system could propel and navigate untethered medical microdevices and micro-nanorobots in the human vasculature. The main problem with these devices is that the metal necessary for magnetic propulsion may corrode and induce cytotoxic effects. The challenge, then, is to find an alloy with low corrosion yet providing an adequate magnetization level for propulsion in often stringent physiological conditions. Because of their high magnetization, we studied the corrosion behavior of two iron-cobalt alloys, Permendur (49% Fe, 49% Co, 2% V) and Vacoflux 17 (81% Fe, 17% Co, 2% Cr), in physiological solution by potentiodynamic polarization assay, surface analysis, and corrosion electrolyte analysis. Both alloys exhibited low corrosion parameters such as a corrosion potential (E(corr)) of -0.57 V/SCE and E(corr) of -0.42 V/SCE for Vacoflux 17. The surface of Permendur samples was homogenously degraded. Vacoflux 17 surface was impaired by cracks and crevices. Both alloys had a stoichiometric dissolution in the electrolyte, and they released enough cobalt to induce cytotoxic effects. This study concluded that Fe-Co alloys could be used preferably in medical microdevices if they were coated so as not to come in contact with physiological solutions. PMID:20119943

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

    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

  3. 49 CFR 192.487 - Remedial measures: Distribution lines other than cast iron or ductile iron lines.

    2010-10-01

    ... iron or ductile iron lines. (a) General corrosion. Except for cast iron or ductile iron pipe, each... the purpose of this paragraph. (b) Localized corrosion pitting. Except for cast iron or ductile iron... cast iron or ductile iron lines. 192.487 Section 192.487 Transportation Other Regulations Relating......

  4. Urinary casts

    ... necrosis , viral disease (such as CMV nephritis ), and kidney transplant rejection . Waxy casts can be found in people with advanced kidney disease and chronic kidney failure . White blood cell ( ...

  5. Salt Bath Oxinitriding of Gray Cast Iron

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

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

  6. Hair casts

    Sweta S Parmar

    2014-01-01

    Full Text Available Hair casts or pseudonits are circumferential concretions,which cover the hair shaft in such a way that, it could be easily removed. They are thin, cylindrical, and elongated in length. We present an unusual case of an 8-year-old girl presenting with hair casts. Occurrence of these is unusual, and they may have varied associations. This patient was suffering from developmental delay. It is commonly misdiagnosed as and very important to differentiate from pediculosis capitis.

  7. Anodization of cast aluminium alloys produced by different casting methods

    K. Labisz

    2008-08-01

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

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

    A Hodžić

    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.

  9. Solidification and casting

    Cantor, Brian

    2002-01-01

    INDUSTRIAL PERSPECTIVEDirect chillcasting of aluminium alloysContinuous casting of aluminium alloysContinuous casting of steelsCastings in the automotive industryCast aluminium-silicon piston alloysMODELLING AND SIMULATIONModelling direct chill castingMold filling simulation of die castingThe ten casting rulesGrain selection in single crystal superalloy castingsDefects in aluminium shape castingPattern formation during solidificationPeritectic solidificationSTRUCTURE AND DEFECTSHetergeneous nucleation in aluminium alloysCo

  10. Vascular Cures

    ... Malformation Atherosclerosis Buerger's Disease Carotid Artery Disease Chronic Venous Insufficiency Congenital Vascular Malformation Critical Limb Ischemia (CLI) Deep Vein Thrombosis (DVT) Diabetes and Vascular Disease Fibromuscular Dysplasia High ...

  11. On Tool Failure in Die Casting

    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...

  12. The surface layer of austempered ductile iron investment castings properties

    D. Myszka; M. Kłębczyk; Zych, A.; Kwiatkowski, L.

    2009-01-01

    The article presents a unique process of carbonnitriding and nitriding the precision casting surfaces of austempered ductile iron. The results of the research are pointing that adequate process parameters allow to obtain multiple increase of wear resistance and a significant increase of corrosion resistance. Also, changes of cast microstructure and hardness are presented.

  13. The surface layer of austempered ductile iron investment castings properties

    D. Myszka

    2009-01-01

    Full Text Available The article presents a unique process of carbonnitriding and nitriding the precision casting surfaces of austempered ductile iron. The results of the research are pointing that adequate process parameters allow to obtain multiple increase of wear resistance and a significant increase of corrosion resistance. Also, changes of cast microstructure and hardness are presented.

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

    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.

  15. 49 CFR 192.489 - Remedial measures: Cast iron and ductile iron pipelines.

    2010-10-01

    ... for Corrosion Control 192.489 Remedial measures: Cast iron and ductile iron pipelines. (a) General graphitization. Each segment of cast iron or ductile iron pipe on which general graphitization is found to a... 49 Transportation 3 2010-10-01 2010-10-01 false Remedial measures: Cast iron and ductile...

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

    Décio Cavalet Soares Abuchaim

    2009-12-01

    Full Text Available OBJETIVO: Esse trabalho tem como objetivo analisar os padrões de dominância circulatória de corações humanos, o número de ramos que a artéria coronária direita fornece ao ventrículo esquerdo, o número de ramos que a artéria coronária esquerda fornece ao direito e a presença de anastomoses intercoronarianas, com sua localização e frequência. MÉTODOS: Foram produzidos 25 moldes de corações submetidos à instilação de acrílico colorido e posterior corrosão com ácido clorídrico, no Laboratório de Cirurgia Experimental da FURB. Peças com lesões e cicatrizes não foram usadas. RESULTADOS: Os corações pertenciam a indivíduos de ambos os sexos, sendo 17 (68% de indivíduos do sexo masculino, com idade média de 40,2 anos (15 a 70 anos. A dominância direita ocorreu em 18 (72% peças, com 1, 2, 3 e 4 ramos em 2, 14, 2 e 1 moldes, respectivamente; a dominância esquerda foi observada em 5 (20% casos, com 1 ramo em 4 moldes e 2 em 1 molde; e a dominância balanceada foi verificada em 2 (8% moldes. Houve diferença significativa entre a dominância direita e esquerda (α > 5%, direita e balanceada (α > 5% e sem significância entre esquerda e balanceada (α OBJECTIVES: The aim of this work was to analyze the dominance patterns of the circulation of the human heart, the number of branches from the right coronary artery to the left ventricle, the number of branches from the left coronary artery to the right ventricle and the frequency and location of intercoronary anastomoses. METHODS: Casts were made of 25 hearts by the injection of colored acrylic resin and subsequent corrosion using hydrochloric acid at the experimental surgery laboratory of Furb. Specimens with lesions or scars were discarded. RESULTS: The hearts, from both men (17 - 68% and women (8 - 32%, had a mean age of 40.2 (15 to 70 years-old. Right dominance occurred in 18 (72% subjects, with 1, 2, 3 and 4 branches leading to the left ventricle in 2, 14, 2 and 2 casts, respectively. Left dominance occurred in 5 (20% with 1 branch leading to the right ventricle in 4 molds and 2 in one. Balanced circulation was observed in two molds (8%. There were significant differences between right and left dominance (α > 5% and between right dominance and balanced circulation (α > 5%, however the same was not true between left dominance and balanced circulation (α < 5%. CONCLUSION: The most common form of coronary circulation is right dominance with an average of 2.16 branches leading to the left ventricle: when dominance is left, the average is 1.2 branches. No intercoronary anastomoses were observed.

  17. Nodular cast iron and casting monitoring

    S. Pietrowski; C. Rapiejko

    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.

  18. Nodular cast iron and casting monitoring

    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. About some corrosion mechanisms of AZ91D magnesium alloy

    Ballerini, Gaia [Dipartimento di Chimica, Polo Scientifico di Sesto Fiorentino, Universita di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Fi (Italy)]. E-mail: gaajaba@yahoo.it; Bardi, Ugo [Dipartimento di Chimica, Polo Scientifico di Sesto Fiorentino, Universita di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Fi (Italy); Bignucolo, Roberto [EBU Process Engineering, Progetti, Innovazione, Processo IVECO, Via Lungo Stura Lazio 49, 10156 Torino (Italy); Ceraolo, Giuseppe [EBU Process Engineering, Progetti, Innovazione, Processo IVECO, Via Lungo Stura Lazio 49, 10156 Torino (Italy)

    2005-09-01

    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.

  20. About some corrosion mechanisms of AZ91D magnesium alloy

    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

  1. Enrichment of Casting Surface in Founding Process

    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 1801plate was placed on G25CrSiMnMoNi 4442,54 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.

  2. Vascular Dementia

    RAMOS, ALBERTO R.; Dib, Salim I.; Wright, Clinton B

    2013-01-01

    The purpose of this review is to highlight existing literature on the epidemiology, pathophysiology, and novel risk factors for vascular dementia. We further examine the evidence linking chronic brain hypoperfusion induced by a variety of cardiovascular diseases to the development of vascular dementia. In the elderly, in whom cerebral perfusion is diminished by the aging process, additional reduction in cerebral blood flow stemming from exposure to potentially modifiable vascular risk factors...

  3. Ageing of cast stainless steel components

    The nuclear industry uses cast stainless steels in areas where it is paramount to ensure reactor safety. Investigations into the resistance of cast stainless steels to intergranular stress corrosion cracking (SCC) in simulated light water reactor conditions have shown contrary to expectation, some nuclear grade steels are indeed susceptible to SCC. The paper sets out of determine whether the information available in the various life extension databanks is sufficient for the application of the various empirical and theoretical models to the relevant safety analyses or if not, to identify areas where data is deficient. (Author)

  4. The ancient Chinese casting techniques

    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...

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

    Ambat, Rajan; Aung, Naing Naing; Zhou, W.

    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...... 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....

  6. Special thermite cast irons

    Yu. Zhiguts; I. Kurytnik

    2008-01-01

    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.

  7. Thin Wall Iron Castings

    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.

  8. Corrosion in seawater systems

    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)

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

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

    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.

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

    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.

  12. Casting characteristics of Al-Mg alloy 535 cast in permanent moulds

    Aluminum alloy 535 could be used for automotive and marine applications because of its good corrosion resistance against mild alkaline and salt spray exposure. The majority of components from this alloy are usually produced by sand casting because it is prone to hot shortness and has poor fluidity when poured in permanent moulds. In an attempt to improve its castability in permanent moulds, casting characteristics such as casting fluidity and hot tear resistance have been studied. In addition, the effectiveness of titanium, boron, scandium, zirconium and a combination of selected elements from this group as grain refiners were evaluated. It s shown that alloy 535 exhibits good casting fluidity when poured with adequate metal superheat and that there is significant improvement in hot tear resistance following grain refinement. (author)

  13. Phase Transformation in Cast Superaustenitic Stainless Steels

    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.

  14. Vascular Depression

    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

  15. Development of chloride-induced corrosion in pre-cracked RC beams under sustained loading: Effect of load-induced cracks, concrete cover, and exposure conditions

    Yu, Linwen [Université de Toulouse, UPS, INSA, LMDC, Toulouse (France); Université de Sherbrooke, Quebec (Canada); François, Raoul, E-mail: raoul.francois@insa-toulouse.fr [Université de Toulouse, UPS, INSA, LMDC, Toulouse (France); Dang, Vu Hiep [Hanoi Architectural University, Faculty of Civil Engineering, Hanoi (Viet Nam); L' Hostis, Valérie [CEA Saclay, CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, Gif-sur-Yvette (France); Gagné, Richard [Université de Sherbrooke, Quebec (Canada)

    2015-01-15

    This paper deals with corrosion initiation and propagation in pre-cracked reinforced concrete beams under sustained loading during exposure to a chloride environment. Specimen beams that were cast in 2010 were compared to specimens cast in 1984. The only differences between the two sets of beams were the casting direction in relation to tensile reinforcement and the exposure conditions in the salt-fog chamber. The cracking maps, corrosion maps, chloride profiles, and cross-sectional loss of one group of two beams cast in 2010 were studied and their calculated corrosion rates were compared to that of beams cast in 1984 in order to investigate the factors influencing the natural corrosion process. Experimental results show that, after rapid initiation of corrosion at the crack tip, the corrosion process practically halted and the time elapsing before corrosion resumed depended on the exposure conditions and cover depth.

  16. Development of chloride-induced corrosion in pre-cracked RC beams under sustained loading: Effect of load-induced cracks, concrete cover, and exposure conditions

    This paper deals with corrosion initiation and propagation in pre-cracked reinforced concrete beams under sustained loading during exposure to a chloride environment. Specimen beams that were cast in 2010 were compared to specimens cast in 1984. The only differences between the two sets of beams were the casting direction in relation to tensile reinforcement and the exposure conditions in the salt-fog chamber. The cracking maps, corrosion maps, chloride profiles, and cross-sectional loss of one group of two beams cast in 2010 were studied and their calculated corrosion rates were compared to that of beams cast in 1984 in order to investigate the factors influencing the natural corrosion process. Experimental results show that, after rapid initiation of corrosion at the crack tip, the corrosion process practically halted and the time elapsing before corrosion resumed depended on the exposure conditions and cover depth

  17. The effects of Δ9-Tetrahydrocannabinole treatment on gonadal micro-vascularization and affected fertility examined by SEM and 3D-morphometry

    Erlbacher, K. M. T.; Minnich, B.

    2015-10-01

    The present study focuses on the effects of Δ9-tetrahydrocannabinol (THC) on the reproductive system in nude rats with special emphasis on how Δ9-THC impacts the vascularization of testes which in turn indirectly influences fertility. Basically, Δ9-tetrahydrocannabinol (THC) causes not only negative (psychoactive) effects in the human body as cannabinole administration in medical use (dose-dependent) offers multiple new treatment opportunities such as pain relief or containment of various cancers. Concerning the reproductive system it strongly influences CB-receptors along the hypothalamic-pituitary-gonadal axis resulting in reduced plasma testosterone levels. There is also altered sperm quality parameters reported such as sperm motility or sperm count. On the other hand Δ9-THC effects endothelial growth factors (VEGF, Ang-1 etc.) respectively acts on their specific receptors which in turn modify angiogenesis and vascularization of tissues and organs (e.g. tumorous tissues). This leads to new therapeutical strategies in the suppression of various cancers by inhibiting (neo-)vascularization and in turn famishment of tumorous tissues (lack of nutrition supply). Here we studied the micro-vascularization of gonads in a long-term THC-treated nude rat model by vascular corrosion casting, SEM and 3D-morphometry.

  18. Vascular Dementia

    Maria Alekseyevna Cherdak; O.V. Uspenskaya

    2015-01-01

    Vascular dementia is one of the most common causes of dementia after Alzheimer's disease, causing around 15% of cases. However, unlike Alzheimer's disease, there are no licensed treatments for vascular dementia. Progress in the specialty has been difficult because of uncertainties over disease classification and diagnostic criteria, controversy over the exact nature of the relation between cerebrovascular pathology and cognitive impairment, and the paucity of identifiable tractable treatment ...

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

    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...

  20. Assessment of Corrosion Behavior of Ductile Irons by Factorial Experiments

    Surendranathan, A. O.; Narayan Prabhu, K.; Sudhaker Nayak, H. V.

    2009-12-01

    The corrosion behavior of unalloyed and alloyed ductile irons (as cast, annealed, and cold worked) in sea water, dilute sulfuric acid, and dilute sodium hydroxide solutions was assessed. Specimen history had a significant effect on the corrosion potential except in ductile iron alloyed with Ni. When the specimens were subjected to different levels of cold working, the corrosion rate was influenced by both the history and the medium. Temperature had a significant effect on the corrosion rate except in the case of unalloyed ductile iron. Factorial experiments indicated that the cold-worked samples were more sensitive to the effect of temperature and composition on the corrosion rate as compared to annealed and as-cast samples. The medium had a significant effect on the corrosion rate in all the cases.

  1. [Vascular system in the large intestine of the dog (Canis lupus f. familiaris)].

    Zahner, M; Wille, K H

    1996-06-01

    The vascular system of the large intestine of 10 dogs was examined by means of vascular corrosion casts, histology and transmission-electron microscopy. The tela submucosa contains an arterial and a venous vascular plexus. In broader areas of the submucosa, a deep and a superficial vascular plexus, which are interconnected, can be found. The plexus are orientated parallel to the layers of the intestinal wall. On the one hand, these vessels naturally provide self-sufficiency and drainage of the submucosa, and, moreover, direct branches to the stratum circulare of the muscular layer. On the other hand, the submucosal vascular plexus is the 'distributional network' for the functional plexus of the tunica mucosa. The arteries, which ascend to the tunica mucosa, supply a flat arterial network underneath the intestinal glands. Bundles of only a few arteriolae originate from this in order to supply the pericryptal capillaries. In the vicinity of the cryptal orifices, these turn into a network of subepithelial capillaries, which is post-connected to the periglandular capillary plexus. From this 'terminal circulatory pathway', the blood is drained off by veins that enter the submucosal plexus. It is characteristic that the postcapillary venules often begin as part of the capillary network. As in other species, the subepithelial capillaries are pre-dominantly lined with a 'fenestrated endothelium', whereas the capillaries of the pericryptal areas show a continuous endothelium. The latter contains multiple vesicles that may fuse in order to form transcytoplasmic channels as a morphological equivalent for transcappillar-epithelial and vice versa occurring transport of substances. PMID:8766402

  2. The corrosion resistance of two non-noble alloys

    Capelo, Sofia; Fernandes, JCS; Proença, L; Fonseca, ITE

    2013-01-01

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

  3. High temperature corrosion of metals

    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)

  4. Advanced rotary engine components utilizing fiber reinforced Mg castings

    Goddard, D.; Whitman, W.; Pumphrey, R.; Lee, C.-M.

    1986-01-01

    Under a two-phase program sponsored by NASA, the technology for producing advanced rotary engine components utilizing graphite fiber-reinforced magnesium alloy casting is being developed. In Phase I, the successful casting of a simulated intermediate housing was demonstrated. In Phase II, the goal is to produce an operating rotor housing. The effort involves generation of a material property data base, optimization of parameters, and development of wear- and corrosion-resistant cast surfaces and surface coatings. Results to date are described.

  5. Corrosion protection

    Brown, Donald W.; Wagh, Arun S.

    2003-05-27

    There has been invented a chemically bonded phosphate corrosion protection material and process for application of the corrosion protection material for corrosion prevention. A slurry of iron oxide and phosphoric acid is used to contact a warm surface of iron, steel or other metal to be treated. In the presence of ferrous ions from the iron, steel or other metal, the slurry reacts to form iron phosphates which form grains chemically bonded onto the surface of the steel.

  6. Special thermite cast irons

    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.

  7. LLNL casting technology

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

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

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

    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...

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

    ÇOLAK, Murat; Kayikci, Ramazan

    2009-01-01

    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 su...

  10. Aluminide protective coatings on high–temperature creep resistant cast steel

    J. Kubicki; A. Kochmańska

    2009-01-01

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

  11. Corrosion Engineering.

    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…

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

    J. Kilarski

    2010-10-01

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

  13. High quality casting materials

    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.

  14. Fabrication of bulk metallic glasses by centrifugal casting method

    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.

  15. Corrosion inhibitors

    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

  16. Cast iron deterioration with time in various aqueous salt solutions

    Rita Mehra; Aditi Soni

    2002-02-01

    The changes with time in the corrosion rate and corrosion current density on a cast iron electrode in various aqueous salt solutions have been carried out using total immersion test and potentiostatic polarization curves. The concentration of salts taken is expected to be present in potable water. The relative behaviour of these salts towards corrosion has also been studied, which is found to be different from previous studies. The total immersion test parameters viz. weight loss, corrosion rate as well as potentiostatic parameters, open circuit potential, corr, Tafel slopes, corrosion rate, have been calculated by standard methods. Besides these the relative increase in corrosion rate with time as well as the percentage to which corrosion rate should be decreased so as to provide protection towards corrosion have also been calculated. It was found that KCl and NaCl are major contributors than MnSO4, Pb(NO3)2, KI and KBr. The relative increase in corrosion is high in KBr, KI, NaNO3, CaCl2, and less in Pb(NO3)2, NaHCO3 and CaCO3 test solutions. For the reliability of results the data has been statistically analysed.

  17. External corrosion

    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.

  18. Vascular Dementia

    Lee, Ae Young

    2011-01-01

    Many cases of age-related cognitive dementia are caused by cerebrovascular lesions, and various vascular syndromes can lead to cognitive impairment and dementia. Repeated cortical infarcts due to embolic disease of the heart or major cerebral vessels can cause progressive deterioration towards dementia and incapacitation. In classic multi-infarct dementia, cognitive deterioration is stepwise rather than smoothly progressive. While diagnostic technologies have vastly improved and added to gene...

  19. Vascular parkinsonism.

    Sibon, Igor; Fenelon, Gilles; Quinn, Niall P; Tison, Franois

    2004-05-01

    The concept of vascular parkinsonism (VP) has been highly controversial since the initial paper by Critchley in 1929. This review tentatively delineates the extent of the spectrum of VP. Much confusion has arisen owing to the lack of clear definitions of parkinsonism, "atypical parkinsonism" and "pseudoparkinsonism", which we here attempt to define. Confusion has also arisen because incidental vascular lesions occurring in true idiopathic Parkinson's disease (IPD) are up to 10 times more common than parkinsonism due to cerebrovascular disease. VP is clinically heterogeneous. Most often VP is atypical and can be separated from IPD, on the basis of the presence of additional focal signs, and the absence of typical resting tremor in the upper limbs, of true akinesia (i. e.: with decrement and fatiguing of alternating movements), and of definite benefit from levodopa. Exceptionally, VP may mimic IPD or other degenerative diseases such as progressive supranuclear palsy or corticobasal degeneration. The lesions responsible for VP are mostly basal ganglia lacunes and/or subcortical white matter vasculopathy of the "Binswanger" type. Rarely, a single striatal infarct, striatal cribriform cavities or ischaemic changes in the substantia nigra have been described. Vascular "pseudo-parkinsonism" refers to isolated gait disorders called "lower body parkinsonism", "frontal-type gait disorders" or "gait ignition failure" that are reminiscent of, but distinct from, that found in IPD. The pathophysiology of VP is poorly understood. Why some patients develop parkinsonism and others do not, despite the same apparent lesion load, remains a mystery. PMID:15164182

  20. 49 CFR 192.457 - External corrosion control: Buried or submerged pipelines installed before August 1, 1971.

    2010-10-01

    ... current requirements. (b) Except for cast iron or ductile iron, each of the following buried or submerged... 49 Transportation 3 2010-10-01 2010-10-01 false External corrosion control: Buried or submerged... SAFETY STANDARDS Requirements for Corrosion Control 192.457 External corrosion control: Buried...

  1. New casting coatings

    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)

  2. Casting in Sport

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

    1994-01-01

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

  3. Multi-layers castings

    J. Szajnar; P. Wrbel; T. Wrbel

    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 200450 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 ...

  4. Arterial vascularization of the uropygial glands (Gl. uropygialis) in geese (Anser anser) and ducks (Anas platyrhynches).

    Aslan, K; Ozcan, S; Kurtul, I

    2000-10-01

    In the present study, arterial vascularization of the uropygial glands (Gl. uropygialis) of 10 adult geese (Anser anser) and 10 adult ducks (Anas platyrhynches) were studied. Takilon was injected into the median coccygeal arteries of six specimens from each species, and Latex (a natural rubber with ammonia) into those of four specimens. Takilon-injected specimens were corrosion casted, and arteries nourishing the gland were revealed via dissection. Vascularization of the uropygial glands of both the goose and the duck was observed to be the right (a. gl. uropygii dextra), left (a. gl. uropygi sinistra) and ventral (a. gl. uropygi ventralis) glandular uropygial arteries, arising from the median coccygeal (a. coccygea media) artery. Both the right and left glandular uropygial arteries were observed, divided into four branches as follows; muscular ramus (ramus muscularis), medial ramus (ramus medialis), ventral ramus (ramus ventralis) and lateral ramus (ramus lateralis). Of these, as the lateral, medial and ventral branches feed the gland, the muscular branch provides blood for the lateral coccygeal (m. coccygealis lateralis) and levator coccygeal (m. levator coccygealis) muscles, and the skin. Among the arteries mentioned above, anastomosis between the first and the second branches of the right ventral uropygial arteries in the five geese and five ducks was found. PMID:11103518

  5. Prediction of corrosion rates of water distribution pipelines according to aggressive corrosive water in Korea.

    Chung, W S; Yu, M J; Lee, H D

    2004-01-01

    The drinking water network serving Korea has been used for almost 100 years. Therefore, pipelines have suffered various degrees of deterioration due to aggressive environments. The pipe breaks were caused by in-external corrosion, water hammer, surface loading, etc. In this paper, we focused on describing corrosion status in water distribution pipes in Korea and reviewing some methods to predict corrosion rates. Results indicate that corrosive water of lakes was more aggressive than river water and the winter was more aggressive compared to other seasons. The roughness growth rates of Dongbok lake showed 0.23 mm/year. The high variation of corrosion rates is controlled by the aging pipes and smaller diameter. Also the phenolphthalein test on a cementitious core of cement mortar lined ductile cast iron pipe indicated the pipes over 15 years old had lost 50-100% of their lime active cross sectional area. PMID:14982159

  6. Quality control of cast brake discs

    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.

  7. Degradation of stainless castings. A literature study

    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

  8. Corrosion-electrochemical behaviour and mechanical properties ofaluminium alloy-321, alloyed by barium

    The purpose of present work is studying of influence of barium additionson electrochemical corrosion of casting aluminium-copper alloy Al-321,containing as base alloying components copper, chromium, manganese, titanium,zirconium, cadmium

  9. Humid-air and aqueous corrosion models for corrosion-allowance barrier material

    Humid-air and aqueous general and pitting corrosion models (including their uncertainties) for the carbon steel outer containment barrier were developed using the corrosion data from literature for a suite of cast irons and carbon steels which have similar corrosion behaviors to the outer barrier material. The corrosion data include the potential effects of various chemical species present in the testing environments. The atmospheric corrosion data also embed any effects of cyclic wetting and drying and salts that may form on the corroding specimen surface. The humid-air and aqueous general corrosion models are consistent in that the predicted humid-air general corrosion rates at relative humidities between 85 and 100% RH are close to the predicted aqueous general corrosion rates. Using the expected values of the model parameters, the model predicts that aqueous pitting corrosion is the most likely failure mode for the carbon steel outer barrier, and an earliest failure (or initial pit penetration) of the 100-mm thick barrier may occur as early as about 500 years if it is exposed continuously to an aqueous condition at between 60 and 70 degrees C

  10. Cast iron - a predictable material

    Jorg C. Sturm; 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...

  11. Caste and power

    Roy, Dayabati

    2011-01-01

    This paper explores the institution of caste and its operation in a micro-level village setting of West Bengal, an Indian state, where state politics at grass roots level is vibrant with functioning local self-government and entrenched political parties. This ethnographic study reveals that caste...

  12. Multi-layers castings

    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 200450 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.

  13. Corrosion amalgams

    The release of copper, mercury, silver, tin or zinc from conventional, dispersed phase and spherical high copper content amalgams immersed in artificial saliva solutions for periods up to 30 d has been measured using nuclear tracer techniques. During initial corrosion, i.e. within a few hours, substantial amounts of mercury were found to be present in particulate matter in the three types of amalgams. The release of particulate matter was pronounced for the dispersed phase type of amalgam. After about 30 d electrochemical corrosion was found to be the predominant process for release of various corrosion products. Zinc was demonstrated to be the major corrosion product released to the artificial saliva solutions from conventional as well as dispersed phase amalgams. Due to low radioactivity levels silver and tin could not be quantitatively asayed. However, the upper limits of release of silver and tin in the artificial saliva solutions referring to exposure periods up to 30 d were estimated to 0.1 μg and 25 μg respectively. The chemical state of the various corrosion products has been evaluated. The deposition of CuCl2 . 3 Cu(OH)2 on the surfaces of copper rich amalgams was observed according to X-ray diffraction analysis. (author)

  14. Corrosion studies of A216 grade WCA steel in hydrothermal magnesium-containing brines

    The US Department of Energy's Salt Repository Project (SRP) is investigating the general corrosion resistance of cast mild steel as a candidate material for waste package containers. Evaluation of this material is being performed at the Pacific Northwest Laboratory in environments simulating expected repository conditions. General corrosion studies of mild steel (ASTM A216 grade WCA) in the as-cast and normalized conditions were conducted in hydrothermal halite-saturated (saturated at ambient temperature) brine environments simulating a ''dissolution'' and an ''inclusion'' brine. Corrosion tests were also performed in brines similar to the inclusion brine but containing magnesium concentrations ranging from 1000 to 30,000 ppM to investigate the effect of magnesium on the corrosion behavior. Corrosion rates of the cast mild steel were found to increase with increasing temperature and with increasing magnesium concentration. Some possible mechanisms that explain the observed behavior are presented. 8 refs., 7 figs., 2 tabs

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

    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

  16. The ancient Chinese casting techniques

    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.

  17. DEFINING PHYSIOLOGICAL PARAMETERS FOR ENGINEERING A VASCULAR MEDIA MODEL

    U Cheema, E. A. H.; N Tamimi, B. A.; V Mudera, R. A. B.

    2008-01-01

    INTRODUCTION: Tissue engineering of a blood vessel structure requires an understanding of the parameters governing the survival of resident vascular smooth muscle cells. We have developed a collagen-based vascular media model to examine the correlation between cell density, O2 requirements and cell viability. METHODS: Collagen type I gels were cast in rectangular wells and were compressed to produce 100μm thin, dense collagen sheets1. These were subsequently spiraled around a mandrel to mimic...

  18. Corrosion behaviour of solution nitrided stainless steels

    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.)

  19. Clean Metal Casting

    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.

  20. Casting in sport.

    Decarlo, M; Malone, K; Darmelio, J; Rettig, A

    1994-03-01

    Attempts by sports medicine professionals to return high school athletes with hand and wrist injuries to competition quickly and safely have been the source of confusion and debate on many playing fields around the country. In addition to the differing views regarding the appropriateness of playing cast usage in high school football, a debate exists among sports medicine professionals as to which material is best suited for playing cast construction. Materials used in playing cast construction should be hard enough to provide sufficient stabilization to the injured area and include adequate padding to absorb blunt impact forces. The purpose of the biomechanical portion of this investigation was to attempt to determine the most appropriate materials for use in constructing playing casts for the hand and wrist by assessing different materials for: 1) hardness using a Shore durometer, and 2) ability to absorb impact using a force platform. Results revealed that RTV11 and Scotchcast were the "least hard" of the underlying casting materials and that Temper Stick foam greatly increased the ability of RTV11 to absorb impact. Assessment of the mechanical properties of playing cast materials and review of current developments in high school football rules are used to aid practitioners in choosing the most appropriate materials for playing cast construction. PMID:16558257

  1. Vascular Access for Hemodialysis

    ... 345 KB)​​​​​ Alternate Language URL Vascular Access for Hemodialysis Page Content On this page: What is a ... Set Up the Vascular Access Well before Starting Hemodialysis Patients should set up a vascular access well ...

  2. Symptomatic stent cast.

    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.

  3. What can be done about corrosion in submersible pumps?

    Minett, S.

    2000-09-01

    Useful advice and a survey of materials and techniques which can help counter corrosion risks in submersible pumps are provided. The greatest risk of corrosion is caused by sea water, hydrochloric acid, certain types of solvents, hydrogen sulphide, liquids with a high copper content, bases with a high pH value and certain liquids containing a mixture of acids. Counteractive strategies suggested include using a corrosion resistant material such as stainless steel, or other resistant coatings and materials for particular components that are exposed to high corrosion risks. Most submersible pumps are made of cast iron which should present no corrosion problems in normal domestic use. In mining and construction applications aluminum submersibles are common, which is resistant to a pH value of about 8. The use of stainless steel is recommended as the main material in submersible pumps when used for pumping acidic liquids, and when purity of the liquid pumped is of prime consideration. Coatings and anodes on conventional cast iron pumps are a less expensive and more flexible alternative against salt water corrosion. Among coatings epoxy coating is the most widely used. Zinc anodes are used in conjunction with epoxy coatings, which by setting up a micro current by contact with the cast iron prevent corrosion of areas of the cast iron that may be exposed as a result of post-production scratching. By being sacrificially corroded, the zinc anodes thus significantly extend the life of a coated pump. Impressed current from an external power source, is an effective, but more expensive alternative to the implanted anode method. Using resistant materials such as nitrile rubber, fluoro-carbon rubber, corrosion resistant cemented carbide, or chlorinated rubber for various components (rotating shaft seals, rubber 'O' rings, cable sheathing, etc) are other alternatives that may be depending on the application and the degree of exposure.

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

    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.)

  5. Container materials for the disposal of high-level radioactive wastes: Corrosion chemistry aspects

    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 1000 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 archaeological 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. (author)

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

    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, us...

  7. Bimetallic layered castings alloy steel – grey cast iron

    T. Wróbel

    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...

  8. Bainite obtaining in cast iron with carbides castings

    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.

  9. Bainite obtaining in cast iron with carbides castings

    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.

  10. Influence of continuous casting conditions on grey cast iron structure

    J. Szajnar; M. Stawarz; T. Wrbel; W. Sebzda; B. Grzesik; M. St?pie?

    2010-01-01

    Purpose: The main aim of investigations was the unification of flake graphite morphology in cast iron ingots in conditions of forced convection of liquid metal in the continuous casting mould, which contains electromagnetic stirrer.Design/methodology/approach: To investigations of grey cast iron ingots were used laboratory stand of continuous casting, which contains continuous casting mould with inductor of rotate electromagnetic field.To investigations were made metallographic researches on ...

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

    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: 850-1050C 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. Samples 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.

  12. Underground pipeline corrosion

    Orazem, Mark

    2014-01-01

    Underground pipelines transporting liquid petroleum products and natural gas are critical components of civil infrastructure, making corrosion prevention an essential part of asset-protection strategy. Underground Pipeline Corrosion provides a basic understanding of the problems associated with corrosion detection and mitigation, and of the state of the art in corrosion prevention. The topics covered in part one include: basic principles for corrosion in underground pipelines, AC-induced corrosion of underground pipelines, significance of corrosion in onshore oil and gas pipelines, n

  13. Pitting corrosion resistant austenite stainless steel

    van Rooyen, D.; Bandy, R.

    A pitting corrosion resistant austenite stainless steel comprises 17 to 28 wt. % chromium, 15 to 26 wt. % nickel, 5 to 8 wt. % molybdenum, and 0.3 to 0.5 wt. % nitrogen, the balance being iron, unavoidable impurities, minor additions made in the normal course of melting and casting alloys of this type, and may optionally include up to 10 wt. % of manganese, up to 5 wt. % of silicon, and up to 0.08 wt. % of carbon.

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

    Finkenstadt, Victoria L; Ct, 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

  15. Corrosion/95 conference papers

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

  16. Casting AISI 316 steel by gel cast

    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)

  17. The Development of Corrosion Resistant Zirconium Alloy

    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 β-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 thatβ-quenching of Zr alloy which was followed by tempering can turn αmartensite into tempered α1martensit. 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)

  18. Calculated phase diagrams, iron tolerance limits, and corrosion of Mg-Al alloys

    Liu, Ming; Uggowitzer, Peter J.; Schmutz, Patrik; Atrens, Andrej

    2008-12-01

    The factors determining corrosion are reviewed in this paper, with an emphasis on iron tolerance limit and the production of high-purity castings. To understand the iron impurity tolerance limit, magnesium phase diagrams were calculated using the Pandat software package. Calculated phase diagrams can explain the iron tolerance limit and the production of high-purity castings by means of control of melt conditions; this is significant for the production of quality castings from recycled magnesium. Based on the new insight, the influence of the microstructure on corrosion of magnesium alloys is reviewed.

  19. Fabrication and ageing of cast austenitic steels

    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

  20. Seal welded cast iron nuclear waste container

    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.

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

    Lenka Bukovinov; Michal Bukovina; Filip Pastorek

    2014-01-01

    The influence of the microstructure of as-cast AZ91 magnesium alloy, which applied to solution annealingtreatment andageingtreatment 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 potentia...

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

    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. Aqueous Corrosion Characteristics of Nickel Aluminides

    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

  4. Corrosion Behaviour of Alpha Phase Aluminium Bronze Alloy in Selected Environments

    Oluwayomi BALOGUN; Joseph BORODE; Kenneth ALANEME; Michael BODUNRIN

    2014-01-01

    This research investigated the corrosion behaviour of aluminium (8 wt %) bronze alloys produced via sand casting in acidic, alkaline, and marine environments. The aluminium bronze was produced from aluminium (6063) alloy and copper scraps by sand casting according to European standard specification (UNS. C61400-CuAl8), after which they were cut into smaller sizes and immersed in the selected corrosive media for corrosion test investigation. H2SO4, NaCl, NaOH, and HCl of 0.1 M, 0.2 M, 0.3 M, 0...

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

    Leszek A. Dobrzański

    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<.

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

    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.

  7. Streptococcus mutans attachment on a cast titanium surface

    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.

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

    Z. Stradomski

    2010-07-01

    Full Text Available The paper presents the results of investigations concerning the influence of σ 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 δ → γ’+ σ. The examinations of corrosion resistance have revealed that the ageing process after supersaturation do not cause significant changes in the anti-corrosive properties.

  9. The substitution of molybdenum by vanadium in high alloy castings

    The possibility of substituting molybdenum with vanadium both partially and completely in high alloy castings because of vanadium's availability in Southern Africa and its relatively lower cost, was studied. The high alloy castings used in the investigation include: ACl Types CF-8M and CG-8M, alloys similar to ACl Type CN-7M and the proprietory grade nickel-base alloys Hastelloy B and Hastelloy C. They were investigated, with respect to general corrosion resistance in phosphoric, sulphuric and hydrochloric acid and localised attack in chloride media, using potentiodynamic and immersion tests conforming to ASTM standards. Vanadium emerges as an inadequate substitute except with the cast austenitic stainless steels where it may find limited application as a partial substitute

  10. EVALUATION OF SILICATE AND PHOSPHATE COMPOUNDS FOR CORROSION CONTROL

    Various dosages of selected silicate and phosphate compounds were evaluated for their ability to inhibit corrosion of cast iron, copper, lead, and galvanized steel specimens in drinking water. The compounds selected for study were zinc polyphosphate (Calgon C-39), zinc orthophosp...

  11. Corrosion behavior of carbon steels under tuff repository environmental conditions

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

  12. Corrosion behavior of carbon steels under tuff repository environmental conditions

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

  13. The effect of radiation on the anaerobic corrosion of steel

    Smart, N. R.; Rance, A. P.; Werme, L. O.

    2008-09-01

    To ensure the safe encapsulation of spent nuclear fuel elements for geological disposal, SKB of Sweden are considering using a canister, which consists of an outer copper canister and a cast iron insert. Previous work has investigated the rate of gas generation due to the anaerobic corrosion of ferrous materials over a range of conditions. This paper examines the effect of radiation on the corrosion of steel in repository environments. Tests were carried out at two temperatures (30 C and 50 C), two dose rates (11 Gray h -1 and 300 Gray h -1) and in two different artificial groundwaters, for exposure periods of several months. 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.

  14. The effect of radiation on the anaerobic corrosion of steel

    To ensure the safe encapsulation of spent nuclear fuel elements for geological disposal, SKB of Sweden are considering using a canister, which consists of an outer copper canister and a cast iron insert. Previous work has investigated the rate of gas generation due to the anaerobic corrosion of ferrous materials over a range of conditions. This paper examines the effect of radiation on the corrosion of steel in repository environments. Tests were carried out at two temperatures (30 deg. C and 50 deg. C), two dose rates (11 Gray h-1 and 300 Gray h-1) and in two different artificial groundwaters, for exposure periods of several months. 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

  15. Corrosion resistance and microstructure of alloy 625 weld overlay on ASTM A516 grade 70

    Nickel-based alloys are a crucial class of materials because of their excellent corrosion resistance. In the present study, single layer and two layers alloy 625 weld overlays were deposited by GTAW process on A516 grade 70 carbon steel. The dilution in terms of Fe, Ni, Mo and Nb content was calculated in 30 points of weld overlay. Microstructure observations showed that alloy 625 had austenitic structure with two types of Laves and NbC secondary phases. The uniform and pitting corrosion resistance of alloy 625 weld overlay as casted and as forged were evaluated in accordance with ASTM G48-2011 standard at different temperatures to determine the weight loss and critical pitting temperature. For achieving a better comparison, samples from alloy 625 as casted and as forged were tested under the same conditions. The results point out that single layer alloy 625 weld overlay is not suitable for chloride containing environments, two layers alloy 625 weld overlay and alloy 625 as casted have acceptable corrosion resistance and almost the same critical pitting temperature. Alloy 625 as forged has the best corrosion resistance and the highest critical pitting temperature among all test specimens. Also, the corrosion behavior was evaluated in accordance with ASTM G28 standard. The corrosion rate of single layer weld overlay was unacceptable. The average corrosion rate of two layers weld overlay and in casted condition were 35.82 and 33.01 mpy, respectively.

  16. Vascular malformations: localized defects in vascular morphogenesis.

    Brouillard, P; Vikkula, M

    2003-05-01

    Vascular anomalies are localized defects of the vasculature, and usually affect a limited number of vessels in a restricted area of the body. They are subdivided into vascular malformations and vascular tumours. Most are sporadic, but Mendelian inheritance is observed in some families. By genetic analysis, several causative genes have been identified during the last 10 years. This has shed light into the pathophysiological pathways involved. Interestingly, in most cases, the primary defect seems to affect the characteristics of endothelial cells. Only mutations in the glomulin gene, responsible for hereditary glomuvenous malformations, are thought to directly affect vascular smooth-muscle cells. PMID:12752563

  17. Corrosion/94 conference papers

    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 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

  18. Corrosion and hydrogen permeation of A216 grade WCA steel in hydrothermal magnesium-containing brines

    The US Department of Energy's Salt Repository Project (SRP) is investigating the general corrosion resistance of cast mild steel as a candidate material for waste package containers. Evaluation of this material is being performed at the Pacific Northwest Laboratory in environments simulating expected repository conditions. The present work addresses two potential failure modes of the reference waste package container: failure by general corrosion processes, and failure by internal hydrogen pressurization by permeation of corrosion product hydrogen. General corrosion studies of mild steel (ASTM A216 grade WCA) in the as-cast and normalized conditions were conducted in hydrothermal halite-saturated (saturated at ambient temperature) brine environments simulating a dissolution and an inclusion brine. Corrosion tests were also performed in brines similar to the inclusion brine but containing magnesium concentrations ranging from 1,000 to 30,000 ppm to investigate the effect of magnesium on the corrosion behavior. In addition, long-term (to 18 months) corrosion tests have been carried out using two-phase salt/brine environments (excess salt tests). Corrosion rates of the cast mild steel in brine were found to increase with increasing temperature and with increasing magnesium concentration. Some possible mechanisms that explain the observed behavior are presented. The corrosion rates observed in the excess-salt tests tend to decrease with time, at 200 degree and 150 degree C; and as-cast material corrodes more slowly than does normalized material. Corrosion-product hydrogen rapidly permeated a mild steel tubing corrosion/permeation specimen immersed in brine. The rate of permeation at 150 degree C was high enough to cause concern regarding potential container overpressurization

  19. Casting Characteristics of Aluminum Die Casting Alloys

    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.

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

    M. Gajewski

    2012-12-01

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

  1. Characterization of Al-Mn particles in AZ91D investment castings

    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

  2. On Potentials of Ferrous Electrodes in Soil Corrosion Cells

    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.

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

    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; Mller, 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 nanotomm measurement was compared with its corresponding measurement acquired at the beamline P05 at PETRA III at DESY, Hamburg, Germany.

  4. Wear resistance of cast iron

    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.

  5. HYDROMODELLING OF CASTING PROCESSES

    E. I. Marukovich

    2016-02-01

    Full Text Available The description of equipment for hydrodynamic experiments and methods of hydromodeling of foundry processes, allowing to carry out three-dimensional modeling of filling process, is given. This method can be used for identification of numerical models and development of casting technology of the new types of production.

  6. Extrusion cast explosive

    Scribner, Kenneth J.

    1985-01-01

    Improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst are disclosed. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants.

  7. Casting warpage study

    Patterson, E.P.

    1976-08-01

    Because of a need to reduce warpage in investment castings, and because of reported success in the use of aqueous polyalkylene glycol solutions for reducing warpage in heat-treated sheet-metal parts, particularly for aluminum alloys, an experiment was designed to include these solutions along with polyethylene glycol solutions in a study of quenching parameters. At the time of the study, the cost of polyethylene glycol was approximately one-third that of polyalkylene glycol. A total of 1032 cast parts was produced from 13 cast-furnace heats for study. Conclusions concerning warpage and mechanical properties were based on 2064 tensile specimens and the cast parts. Warpage was reduced significantly in the two glycol-solution systems. Solutions of 20 and 40 percent, by weight, appeared to be more effective for both polyethylene glycol and polyalkylene glycol. Minimum warpage occurred at a quenching temperature of 210/sup 0/F (98.9/sup 0/C). Warpage in the glycol quenching solutions was less than that which occurred in water at all temperatures studied. The average warpage of the parts was affected by their attitude during quenching. This warpage was caused by differential cooling rates on the forward and rear surfaces of the parts produced by the turbulence created by the downward motion of the basket during the quenching operation. Parts which displayed thin edges upon approach to the quenching solution showed less tendency to warp than did those which displayed broad surfaces.

  8. Electrokinetically supported pressure casting

    Krueger, H.G.; Schindler, U. [Technische Univ. Ilmenau (Germany). Fakultaet fuer Maschinenbau

    2001-02-01

    On the basis of the physical operating principles characterizing electrokinetically supported pressure casting, two different processing arrangements and their relative efficiency are discussed. The investigations were conducted with a porcelain slip in a small-sized laboratory pressure casting plant. A combination of pressure filtration and electrophoresis/electroosmosis is especially effective if the filtrate volume flows of both pressure filtration and electroosmosis have the same direction. This is the case for one-sided filtration, where casting time reductions of 75% could be realized by electrokinetic effects. Furthermore, the electrical field effects enable body shaping at very low shot pressures of 5 or 10 bar. Well-balanced body shaping could be achieved at a pressure of 25 bar and at an electric current density of 7 mA/cm{sup 2}. For double-sided filtration, the filtrate volume flows add to each other only at the cathode side. The filtrate volume flows of pressure filtration and electroosmosis subtract from each other close to the anode, leading to a low amount of filtrate at the anode side. Furthermore, the centre of the symmetrically inwards-directed gradient of moisture, which is the typical situation for pressure casting, is shifted away from the centre of the green body. (orig.)

  9. Bimetallic layered castings alloy steel – carbon cast steel

    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...

  10. Computer cast blast modelling

    Chung, S. [ICI Explosives Canada, North York, ON (Canada); McGill, M. [ICI Explosives USA, Dallas, TX (United States); Preece, D.S. [Sandia National Labs., Albuquerque, NM (United States)

    1994-07-01

    Cast blasting can be designed to utilize explosive energy effectively and economically for coal mining operations to remove overburden material. The more overburden removed by explosives, the less blasted material there is left to be transported with mechanical equipment, such as draglines and trucks. In order to optimize the percentage of rock that is cast, a higher powder factor than normal is required plus an initiation technique designed to produce a much greater degree of horizontal muck movement. This paper compares two blast models known as DMC (Distinct Motion Code) and SABREX (Scientific Approach to Breaking Rock with Explosives). DMC, applies discrete spherical elements interacted with the flow of explosive gases and the explicit time integration to track particle motion resulting from a blast. The input to this model includes multi-layer rock properties, and both loading geometry and explosives equation-of-state parameters. It enables the user to have a wide range of control over drill pattern and explosive loading design parameters. SABREX assumes that heave process is controlled by the explosive gases which determines the velocity and time of initial movement of blocks within the burden, and then tracks the motion of the blocks until they come to a rest. In order to reduce computing time, the in-flight collisions of blocks are not considered and the motion of the first row is made to limit the motion of subsequent rows. Although modelling a blast is a complex task, the DMC can perform a blast simulation in 0.5 hours on the SUN SPARCstation 10--41 while the new SABREX 3.5 produces results of a cast blast in ten seconds on a 486-PC computer. Predicted percentage of cast and face velocities from both computer codes compare well with the measured results from a full scale cast blast.

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

    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

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

    M. Cholewa; S. Tenerowicz; T. Wrbel

    2008-01-01

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

  13. Low toxicity corrosion inhibitors

    This paper discusses the design and testing of low toxicity corrosion inhibitors. New chemistries have been investigated with respect to corrosion protection and impact on the marine environment. The resulting chemicals, while they are effective corrosion inhibitors, present significant improvements in terms of environmental properties over current products. The discussion includes results of the corrosion inhibition, toxicity, biodegradability and partitioning studies

  14. Thermal aging of cast duplex stainless steels

    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

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

    S. J. Świłło

    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.

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

    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

  17. Towards Corrosion Detection System

    B.B. Zaidan; A.A. Zaidan; Hamdan.O.Alanazi; Rami Alnaqeib

    2010-01-01

    Corrosion is a natural process that seeks to reduce the binding energy in metals. The end result of corrosion involves a metal atom being oxidized. Surface corrosion on aluminum aircraft skins, near joints and around fasteners, is often an indicator of buried structural corrosion and cracking In this paper we proposed a new method on which we are moving towards designing a method to detect the corrosion within the metals, the new method has defined texture analysis as the main method for this...

  18. Cast iron - a predictable material

    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抯 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.

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

    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.

  20. Microstructure, Bio-corrosion Behavior, and Corrosion Residual Strength of High Strain Rate Rolled Mg-4Zn Alloy Sheet

    Zou, Zhengyang; Chen, Jihua; Yan, Hongge; Su, Bin; Gong, Xiaole

    2016-04-01

    Microstructure, bio-corrosion behavior, and corrosion residual strength in 0.9 wt.% NaCl solution of the fine-grained Mg-4Zn alloy sheet prepared by high strain rate rolling are systematically investigated. The as-rolled alloy has fine homogenous dynamic recrystallization grains with the average grain size of 4.5 μm. It has different bio-corrosion behavior from the as-cast and is the most corrosion resistant except for pure Mg. Its in vitro strength loss is about 19% after 7 days immersion (the as-cast, 62%), and corrosion residual strength after 15 days immersion is 205 MPa. Its in vitro strength loss after 15, 30, and 60 days immersion are 24, 37, and 38% respectively. The as-rolled Mg-4Zn alloy is featured with the slighter in vitro loss of mechanical integrity due to uniform bio-corrosion and is desirable for the usage in the field of bone fixation.

  1. Microstructure, Bio-corrosion Behavior, and Corrosion Residual Strength of High Strain Rate Rolled Mg-4Zn Alloy Sheet

    Zou, Zhengyang; Chen, Jihua; Yan, Hongge; Su, Bin; Gong, Xiaole

    2016-05-01

    Microstructure, bio-corrosion behavior, and corrosion residual strength in 0.9 wt.% NaCl solution of the fine-grained Mg-4Zn alloy sheet prepared by high strain rate rolling are systematically investigated. The as-rolled alloy has fine homogenous dynamic recrystallization grains with the average grain size of 4.5 μm. It has different bio-corrosion behavior from the as-cast and is the most corrosion resistant except for pure Mg. Its in vitro strength loss is about 19% after 7 days immersion (the as-cast, 62%), and corrosion residual strength after 15 days immersion is 205 MPa. Its in vitro strength loss after 15, 30, and 60 days immersion are 24, 37, and 38% respectively. The as-rolled Mg-4Zn alloy is featured with the slighter in vitro loss of mechanical integrity due to uniform bio-corrosion and is desirable for the usage in the field of bone fixation.

  2. Corrosion/96 conference papers

    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 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

  3. Moving Cast Shadow Detection

    Zhang, Wei; Wu, Q.M. Jonathan; Fang, Xiangzhong

    2007-01-01

    In this chapter, we have provided a brief overview of the works about moving cast shadow detection. The state-of-the-art methods have been categories into color model, textural model, and geometric model according to the information and model utilized, which have been disscussed systemically. Furthermore, all kinds of statistical models have been employed to tackle the problem, which are also analyzed in detail. From the results, we can see that different method is fit for different situation...

  4. The anaerobic corrosion of carbon steel in concrete

    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 μm/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)

  5. Bimetallic layered castings alloy steel – carbon cast steel

    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.

  6. Casting larger polycrystalline silicon ingots

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

    1995-08-01

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

  7. Metal corrosion for nanofabrication.

    Yu, Hai-Dong; Zhang, Zhongping; Han, Ming-Yong

    2012-09-10

    The annual cost of corrosion has been increasing globally, and it has now reached beyond 3% of the world's gross domestic product. It remains a challenge to reduce or prevent unwanted corrosion effectively after many decades of effort. Nowadays, more efforts are being made to develop anti-corrosion platforms for decreasing the huge cost of corrosion. In parallel, it is also highly expected to be able to use corrosion for producing useful materials with reduced energy consumption. In this review, recent progress in how methods for controlling metal corrosion can be used to produce structure-diversified nanomaterials are summarized along with a presentation of their applications. As a valuable addition to the scientists' toolbox, metal corrosion strategies can be applied to different metals and their alloys for the production of various nanostructured materials; this also provides insights into how metal corrosion can be further prevented and into how corrosion wastage can be reduced. PMID:22707341

  8. Corrosion resistance of Elektron 21 magnesium alloy

    A. Kiełbus

    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 β’ phase and precipitations of equilibrium β 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.

  9. Model studies of erosion corrosion at saturated steam turbine components

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

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

    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

  11. Application of isotope dilution for studying corrosion processes in metals

    A radiochemical method based on isotope dilution has been used for investigating the corrosion process in various aggressive agents. The corrosive effects of hydrochloric acid, sulphuric acid and nitric acid on steels 35M-16 and OT-60 as well as on cast iron FC-20 were investigated under various experimental conditions. The non-radioactive iron ions in the solution resulting from the anodic dissolution of the metal sample to be investigated act as internal diluent for the radioactive 55+59Fe3+ ions in the given corrosive system. The corrosion process has been described quantitatively by means of a kinetic parameter called the 'degree of resistivity of the metal sample to the aggressive agent'. (author)

  12. Sea water corrosion of circulating water pumps for thermal and nuclear power stations and countermeasures

    Since about 3 to 4 m3/s cooling water is required for 100 MW power output in thermal power stations and 6 to 7 m3/s in nuclear power stations, power stations in Japan are constructed in coastal areas, and sea water is used as the cooling water. Accordingly the corrosion due to sea water is the important problem to all sea water pumps. The circulating water pumps used for modern thermal power stations and nuclear power stations are vertical shaft pumps, and their main components are immersed in sea water. The composition of sea water is almost invariable in ocean, and the amount of chlorine is in the range from 1.8 to 2.0%, the concentration of dissolved oxygen is 5 to 10 ppm, and pH is 8.1 to 8.3. As for the materials used for circulating water pumps, cast stainless steel is used for the impellers, both cast iron and cast stainless steel are used for the discharge bowls, and the combination of carbon steel shafts and stainless steel sleeves or the stainless steel shafts are adopted. The corrosion arising in circulating pumps is electro-chemical corrosion, and the modes of the corrosion is divided into overall corrosion and local corrosion. The cases of corrosion occurred in circulating pumps and the countermeasures are explained. (Kako, I.)

  13. Fracture Mechanisms in Steel Castings

    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.

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

    Jin, Juntao; Guan, Yuntao

    2014-10-01

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

  15. Cast dielectric composite linear accelerator

    Sanders, David M.; Sampayan, Stephen; Slenes, Kirk; Stoller, H. M.

    2009-11-10

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

  16. Imaging Pediatric Vascular Lesions

    Nguyen, Tuyet A.; Krakowski, Andrew C.; Naheedy, John H.; Kruk, Peter G.

    2015-01-01

    Vascular anomalies are commonly encountered in pediatric and dermatology practices. Most of these lesions are benign and easy to diagnose based on history and clinical exam alone. However, in some cases the diagnosis may not be clear. This may be of particular concern given that vascular anomalies may occasionally be associated with an underlying syndrome, congenital disease, or serious, life-threatening condition. Defining the type of vascular lesion early and correctly is particularly important to determine the optimal approach to management and treatment of each patient. The care of pediatric patients often requires collaboration from a multitude of specialties including pediatrics, dermatology, plastic surgery, radiology, ophthalmology, and neurology. Although early characterization of vascular lesions is important, consensus guidelines regarding the evaluation and imaging of vascular anomalies does not exist to date. Here, the authors provide an overview of pediatric vascular lesions, current classification systems for characterizing these lesions, the various imaging modalities available, and recommendations for appropriate imaging evaluation. PMID:26705446

  17. Skeleton castings dynamic load resistance

    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.

  18. Regulation of Vascular Integrity

    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...

  19. Iatrogenic Vascular Injuries

    Rudström, Håkan

    2013-01-01

    Iatrogenic vascular injuries (IVIs) and injuries associated with vascular surgery can cause severe morbidity and death. The aims of this thesis were to study those injuries in the Swedish vascular registry (Swedvasc), the Swedish medical injury insurance where insurance claims are registered, the Population and Cause of death registries, and in patient records, in order to explore preventive strategies. Among 87 IVIs during varicose vein surgery 43 were venous, mostly causing bleeding in the ...

  20. Unique intermetallics combat wear and corrosion

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

  1. Zinc-The key to preventing corrosion

    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.

  2. Vascular Health Activity Book

    ... Success Stories? Planned Giving Current Contributors Legacy Program Governance Bylaws Research Council Message Funding? Sources and Uses Affiliated Organizations Corporate Partners Corporate Recognition Sponsorship Opportunities Vascular Research Awards ...

  3. Modelling of Corrosion Cracks

    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.

  4. Modelling of Corrosion Cracks

    Thoft-Christensen, Palle

    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.......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....

  5. Cast iron-base alloy for cylinder/regenerator housing

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

    1985-01-01

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

  6. Phase Transformations in Cast Duplex Stainless Steels

    Yoon-Jun Kim

    2004-12-19

    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} and {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 (MA) 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, {sigma} 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.

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

    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

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

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

  9. Tuning the Corrosion Behavior of Rapidly Solidified and Thermally-annealed Fe-Ti-Pd Alloys

    Gonzalez Sanchez, Sergio; Sort, Jordi

    2014-01-01

    The corrosion behavior of rapidly solidified Fe(91-x)Ti9Pdx (x=0, 1, 3 5) alloys (wt. %), both in the as-cast and thermally annealed (i.e., slowly cooled) states, has been investigated by means of electrochemical potentiodynamic polarization and immersion tests. Addition of Pd shifts the corrosion potential towards more anodic values than in the Fe91Ti9 alloy, both in the as-cast and annealed samples. In turn, the processing route (rapid cooling vs. thermal annealing) has a strong influence i...

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

    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)

  11. Erosion-corrosion

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

  12. Microbiological corrosion of metals

    Problems is considered of development of the microbiological corrosion of the NPP equipment. The main attention is paid to the selective character of microbiological corrosion in zones of welded joints of austenitic steels. It is noted that the presence of technological defects promotes growth of corrosional damages. Methods for microbiological corrosion protection are discussed

  13. Organic corrosion inhibitors

    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)

  14. Management of Reinforcement Corrosion

    Küter, André; Geiker, Mette Rica; Møller, Per

    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....

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

    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 μm/a-250 μm/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

  16. Potential dependence of SCC growth of cast stainless steels and weld material in high-temperature water

    SCC growth rates measurements were performed in hydrogenated simulated PWR primary water and oxygenated water environments at 320°C to examine SCC growth behaviors of SCS14A cast stainless steels and 316L weld material using half-inch size compact tension specimens (1/2TCT). The effects of thermal ageing and cold-work on SCC growth were examined in high-temperature water in different corrosion potential environments. And the corrosion behaviors of ferrite (α) and austenite (γ) phases were also investigated after testing in both low- and high- potential water environments to consider the cause of the corrosion potential dependence on SCC growth. The following results were obtained. No significant SCC growth was observed on SCS14A cast stainless steels and 316L weld material in simulated PWR water even after 1 year exposure. No influence on SCC by thermal ageing and cold-working of specimens was recognized after exposure in this simulated PWR primary water. Significant SCC growth was observed in high-potential water and a clear corrosion potential dependence was observed on SCC growth of SCS14A cast stainless steels and 316L weld material. Clear potential dependence on corrosion of ferrite and austenite phases was observed: the ferrite phase corroded more slowly in low-potential water and the austenite phase corroded more significantly in simulated PWR primary water. The difference in corrosion seemed to affect the SCC growth mechanism in PWR primary water. (author)

  17. Segregation in cast products

    A Ghosh

    2001-02-01

    Microsegregation gets eliminated significantly if subsequent hot working and/or annealing are done on cast products. Macrosegregation however persists, causing problems in quality, and hence, has to be attended to. Microsegregation is a consequence of rejection of solutes by the solid into the interdendritic liquid. Scheil’s equation is mostly employed. However, other equations have been proposed, which take into account diffusion in solid phase and/or incomplete mixing in liquid. Macrosegregation results from movements of microsegregated regions over macroscopic distances due to motion of liquid and free crystals. Motion of impure interdendritic liquid causes regions of positive macrosegregation, whereas purer solid crystals yield negative macrosegregation. Flow of interdendritic liquid is primarily natural convection due to thermal and solutal buoyancy, and partly forced convection due to suction by shrinkage cavity formation etc. The present paper briefly deals with fundamentals of the above and contains some recent studies as well. Experimental investigations in molten alloys do not allow visualization of the complex flow pattern as well as other phenomena, such as dendrite-tip detachment. Experiments with room temperature analogues, and mathematical modelling have supplemented these efforts. However, the complexity of the phenomena demands simplifying assumptions. The agreement with experimental data is mostly qualitative. The paper also briefly discusses centreline macrosegregation during continuous casting of steel, methods to avoid it, and the, importance of early columnar-to-equiaxed transition (CET) as well as the fundamentals of CET.

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

    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

  19. The anaerobic corrosion of carbon steel in concrete

    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 μm/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)

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

    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...

  1. Microstructure of Cast Ni-Cr-Al-C Alloy

    Cios G.

    2015-04-01

    Full Text Available Nickel based alloys, especially nickel based superalloys have gained the advantage over other alloys in the field of high temperature applications, and thus become irreplaceable at high temperature creep and aggressive corrosion environments, such as jet engines and steam turbines. However, the wear resistance of these alloys is insufficient at high temperatures. This work describes a microstructure of a new cast alloy. The microstructure consists of ? matrix strengthened by ? fine precipitates (dendrites improving the high temperature strength and of Chromium Cr7C3 primary carbides (in interdendritic eutectics which are designed to improve wear resistance as well as the high temperature strength.

  2. Cast Fe-base cylinder/regenerator housing alloy

    Larson, F.; Kindlimann, L.

    1980-01-01

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

  3. Poikiloderma vasculare atrophicans

    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.

  4. Poikiloderma vasculare atrophicans

    Padmavathy L; Prasad PVS; Prasanna K; Rao L

    1994-01-01

    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.

  5. Lost-Soap Aluminum Casting.

    Mihalow, Paula

    1980-01-01

    Lost-wax casting in sterling silver is a costly experience for the average high school student. However, this jewelry process can be learned at no cost if scrap aluminum is used instead of silver, and soap bars are used instead of wax. This lost-soap aluminum casting process is described. (Author/KC)

  6. DENDRITIC CRYSTALLIZATION OF CAST IRON

    V. Stetsenko

    2015-04-01

    Full Text Available It is shown that crystallization of the main phases in cast iron happens on the dendritic mechanism. The main phases when hardening cast iron are dendrites of austenite, graphite and a cementite. Thermodynamic it is established that spherical graphite represents strongly branched compact dendrite with a sectorial and layered structure.

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

    Banerji, Shankha

    1992-01-01

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

  8. Effect of Heat Treatment on the Corrosion Behavior of Nickel Chromium (Wiron 99) Alloys

    Supreetha SN; Ravindra K.; Murali H

    2010-01-01

    The purpose of this study was to evaluate the corrosion behavior of Nickel chromium alloys (Wiron 99) in the as-cast condition and when subjected to different firing temperatures. This information is important as the firing porcelain on the metal substructure of a restoration may produce changes in corrosion behavior that could influence an alloy behavior during long term use. This study was also designed to study comprehensively the clinical serviceability of these Nickel chromium alloys.

  9. CORROSION BEHAVIOUR OF CHOSEN CONSTRUCTION METALS IN THE DUCT SYSTEM OF THE RECYCLING ALUMINIUM FURNACE

    Tatiana Liptáková; Milan Malcho; Jozef Jandačka

    2010-01-01

    The corrosion behaviour of five types of steels and cast irons proposed for production of the duct system in the recycling aluminium furnace is studied in this article. The metals tested were exposed in the real conditions at high temperature (from 800 to 1100°C ) in very aggressive environment of combustion products for thirty days. The character and intensity of corrosion attack of the tested materials are evaluated by gravimetric and metallographic analysis.

  10. CORROSION BEHAVIOUR OF CHOSEN CONSTRUCTION METALS IN THE DUCT SYSTEM OF THE RECYCLING ALUMINIUM FURNACE

    Tatiana Liptáková

    2010-09-01

    Full Text Available The corrosion behaviour of five types of steels and cast irons proposed for production of the duct system in the recycling aluminium furnace is studied in this article. The metals tested were exposed in the real conditions at high temperature (from 800 to 1100°C in very aggressive environment of combustion products for thirty days. The character and intensity of corrosion attack of the tested materials are evaluated by gravimetric and metallographic analysis.

  11. Colour Metallography of Cast Iron

    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.

  12. [Vascular factors in glaucoma].

    Mottet, B; Aptel, F; Geiser, M; Romanet, J P; Chiquet, C

    2015-12-01

    The exact pathophysiology of glaucoma is not fully understood. Understanding of the vascular pathophysiology of glaucoma requires: knowing the techniques for measuring ocular blood flow and characterizing the topography of vascular disease and the mechanisms involved in this neuropathy. A decreased mean ocular perfusion pressure and a loss of vascular autoregulation are implicated in glaucomatous disease. Early decrease in ocular blood flow has been identified in primary open-angle glaucoma and normal pressure glaucoma, contributing to the progression of optic neuropathy. The vascular damage associated with glaucoma is present in various vascular territories within the eye (from the ophthalmic artery to the retina) and is characterized by a decrease in basal blood flow associated with a dysfunction of vasoregulation. PMID:26597554

  13. Vascular grading of angiogenesis

    Hansen, S; Grabau, D A; Sørensen, Flemming Brandt; Bak, M; Vach, W; Rose, C

    2000-01-01

    The study aimed to evaluate the prognostic value of angiogenesis by vascular grading of primary breast tumours, and to evaluate the prognostic impact of adding the vascular grade to the Nottingham Prognostic Index (NPI). The investigation included 836 patients. The median follow-up time was 11...... years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers...... had clinical impact for 24% of the patients, who had a shift in prognostic group, as compared to NPI, and implied a better prognostic dissemination. We concluded that the angiogenesis determined by vascular grading has independent prognostic value of clinical relevance for patients with breast cancer....

  14. Requirements on cast steel for the primary coolant circuit of water cooled reactors

    The most important requirements placed on the structural components of water cooled nuclear reactors include corrosion resistance and mechanical materials properties. Intercrystalline corrosion resistance was tested using the Strauss Test in compliance with the DIN 50914 Standard. Following sensitization between 600 to 700 degC with a dwell time between 15 minutes and 100 hours, a specimen homogeneously annealed with the casting and rapidly water cooled showed no intercrystalline corrosion. Specimens cooled from 1050 degC at a rate of 100 degC per hour showed no unambiguous tendency for intercrystalline corrosion after sensitization; in some cases, however, an initial attack of intercrystalline corrosion was found. It was found that austenitic Cr-Ni cast steel containing 2.5% Mo and about 15% ferrite showed the sensitive intercrystalline corrosion range at higher temperatures and longer dwell times than rolled Cr-Ni steels. In plating the ferritic cast steel with a corrosion resistant plating material, annealing temperature after welding must not exceed 600 to 620 degC otherwise the resistance of the plated layer against intercrystalline corrosion would not be safeguarded, and following annealing for stress removal at a temperature of 600 to 620 degC all requirements must be satisfied by the weld metal and weld transition placed on the initial material. Martensite materials are used for the manufacture of components which are not used under pressure, such as alloys with 13% Cr and 1% to 6% Ni and alloys with 17% Cr and 4% Ni. Carbon content is maintained below 0.10% to guarantee good weldability and the highest corrosion resistance. Cast steels with 13% Cr and 4% Ni after a dwell of 2500 hours in fully desalinated water without oxygen and with 3600 ppm of boron at a test temperature of 95 to 300 degC showed a surface reduction of 0.005 mm annually. In identical conditions except for the water containing oxygen the reduction in surface was 0.05 mm per year. (J.B.)

  15. Numerical simulation on the solidification structure of Ø600mm continuous casting round bloom

    Fang, Q.; Ni, H. W.; Wang, S. J.; Zang, H.

    2016-03-01

    A FE (Finite Element)—CA (Cellular Automation) coupling model was developed for the simulation of solidification structure formation during the Ø600mm round bloom continuous casting process of Q345E steel. The simulation result of the temperature field was consistent with the nail-shooting experimental result, and the simulated solidification structure of the bloom was in great agreement with corrosion testing under the same casting condition. The simulation results showed that the centre equiaxed crystal ratio increased slightly with the increase of secondary cooling water rate and decreased with the increase of casting temperature and casting speed. When the secondary cooling water rate was over 0.08L/kg, it had less effect on the solidification structure. As the casting temperature increased by 1°C or the casting speed increased by 0.01m/min, the centre equiaxed crystal ratio would decrease by 0.4%∼1.2% and 3%∼0.8% respectively. According to the simulation results, the optimized continuous casting process of Ø600mm round bloom should be the secondary cooling water rate of 0.08L/kg, the casting temperature of 1532°C∼1539°C and the casting speed of 0.20m/min∼0.22m/min. It was found that the solidification structure of Ø600mm Q345E steel round bloom was much improved after the optimized continuous casting process was adopted in practical production.

  16. Corrosion of candidate container materials in air-steam mixtures

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

  17. Study on Corrosion Resistance of Fe-based Amorphous Coating by Laser Cladding in Hydrochloric Acid

    Chen, Q. J.; Guo, S. B.; Yang, X. J.; Zhou, X. L.; Hua, X. Z.; Zhu, X. H.; Duan, Z.

    In this study, the Fe41Co7Cr15Mo14C15B6Y2 bulk amorphous alloy with high glass-forming ability was prepared using the arc- melting copper mold casting technique, and corresponding amorphous coating was obtained using the laser melt amorphous powders on the surface of carbon steel. The corrosion resistance performance of the laser cladding coating in hydrochloric acid was analyzed and tested in experiments under the conditions of different laser cladding speeds. The amorphous alloy coating with different fabrication parameters have the difference internal structure, which lead to the difference corrosion resistance in the same environment to some extent. The nature of amorphous alloy and the corrosion morphology were investigated using XRD and SEM method, respectively. The corrosion experiments showed that: when the laser power was 3300W, the corrosion resistance of four kinds of samples in hydrochloric acid from strong to weak as follows: as-cast sample > the coating with laser cladding speed 110 mm/min > the coating with laser cladding speed 120 mm/min > the coating with laser cladding speed 130 mm/min. The free corrosion current density of casting sample, sample 1, sample 2 and sample 3 is 3.304 × 10-6 A/cm2, 2.600×10-3 A/cm2, 2.030×10-3 A/cm2 and 3.396×10-4 A/cm2, respectively.

  18. INFLUENCE OF MICROSTRUCTURE ON THE CORROSION BEHAVIOUR OF MAGNESIUM ALLOYS

    Pawar, Surajkumar Ganpat

    2011-01-01

    The influence of microstructure on the corrosion behaviour of magnesium alloys has been investigated using advanced microscopy approaches including optical microscopy, SEM, TEM and SKPFM with a focus on the effect of melt-conditioned twin roll casting (MCTRC) and friction stir welding (FSW) on the resultant microstructure of magnesium alloys.The microstructure characterization revealed that intense shearing, generated through the advanced shear technology, resulted in grain refinement and a u...

  19. Control of cast iron and casts manufacturing by Inmold method

    S. Pietrowski

    2009-01-01

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

  20. How to Prevent Vascular Disease

    ... Malformation Atherosclerosis Buerger's Disease Carotid Artery Disease Chronic Venous Insufficiency Congenital Vascular Malformation Critical Limb Ischemia (CLI) Deep Vein Thrombosis (DVT) Diabetes and Vascular Disease Fibromuscular Dysplasia High ...

  1. Kidney Failure and Vascular Disease

    ... Malformation Atherosclerosis Buerger's Disease Carotid Artery Disease Chronic Venous Insufficiency Congenital Vascular Malformation Critical Limb Ischemia (CLI) Deep Vein Thrombosis (DVT) Diabetes and Vascular Disease Fibromuscular Dysplasia High ...

  2. Pediatric vascular access

    Donaldson, James S. [Northwestern University, Feinberg School of Medicine, Department of Medical Imaging, Children' s Memorial Hospital, Chicago, IL (United States)

    2006-05-15

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

  3. Pediatric vascular access

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

  4. Vascular Access in Children

    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.

  5. The stability of cast alloys and CVD coatings in a simulated biomass-combustion atmosphere:

    Skobir, Danijela Anica; Spiegel, Michael

    2006-01-01

    The corrosion resistance in a biomass-combustion environment was studied for the following materials: cast alloys (Alloy 800, Inconel 617, 1.4910, HCM 12 and P91), Fe-9 % Cr model alloys with and without additions of Al, Si and Mo, and cast alloys coated using the pack-cementation process with Al and Al-Si. The simulated atmosphere for the biomass-combustion environment contained 200g/g HCl, volume fractions 13 % COsub2, 22 % Hsub{2}O and 5 % Osub2. The samples were covered with a salt mixtur...

  6. Tribocorrosion studies in centrifugally cast al-matrix siCp-reinforced functionally graded composites

    Velhinho, A.; Botas, J. D.; Ariza, E.; Gomes, J. R.; Rocha, L. A.

    2004-01-01

    The present work reports results obtained from a series of preliminary experiments aiming at complementing the current knowledge about the wear behaviour of centrifugally-cast FGM Al/SiCp composites, through concurrent corrosion processes. Precursor MMCs were prepared by rheocasting, using 118.8 m SiC particles and an Al-10Si2.2 Mg alloy. Those MMCs were then molten and centrifugally cast in order to produce cylindrical FGMMCs. Discs machined from the top surface of each sample wer...

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

    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)

  8. Comparison of marginal accuracy of castings fabricated by conventional casting technique and accelerated casting technique: An in vitro study

    S Srikanth Reddy

    2013-01-01

    Full Text Available Background: Conventional casting technique is time consuming when compared to accelerated casting technique. In this study, marginal accuracy of castings fabricated using accelerated and conventional casting technique was compared. Materials and Methods: 20 wax patterns were fabricated and the marginal discrepancy between the die and patterns were measured using Optical stereomicroscope. Ten wax patterns were used for Conventional casting and the rest for Accelerated casting. A Nickel-Chromium alloy was used for the casting. The castings were measured for marginal discrepancies and compared. Results: Castings fabricated using Conventional casting technique showed less vertical marginal discrepancy than the castings fabricated by Accelerated casting technique. The values were statistically highly significant. Conclusion: Conventional casting technique produced better marginal accuracy when compared to Accelerated casting. The vertical marginal discrepancy produced by the Accelerated casting technique was well within the maximum clinical tolerance limits. Clinical Implication: Accelerated casting technique can be used to save lab time to fabricate clinical crowns with acceptable vertical marginal discrepancy.

  9. Surface films and corrosion of copper

    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

  10. Surface films and corrosion of copper

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

    1999-03-01

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

  11. Sixty Years of Casting Research

    Campbell, John

    2015-11-01

    The 60 years of solidification research since the publication of Chalmer's constitutional undercooling in 1953 has been a dramatic advance of understanding which has and continues to be an inspiration. In contrast, 60 years of casting research has seen mixed fortunes. One of its success stories relates to improvements in inoculation of gray irons, and another to the discovery of spheroidal graphite iron, although both of these can be classified as metallurgical rather than casting advances. It is suggested that true casting advances have dated from the author's lab in 1992 when a critical surface turbulence condition was defined for the first time. These last 20 years have seen the surface entrainment issues of castings developed to a sufficient sophistication to revolutionize the performance of light alloy and steel foundries. However, there is still a long way to go, with large sections of the steel and Ni-base casting industries still in denial that casting defects are important or even exist. The result has been that special ingots are still cast poorly, and shaped casting operations have suffered massive losses. For secondary melted and cast materials, electro-slag remelting has the potential to be much superior to expensive vacuum arc remelting, which has cost our aerospace and defense industries dearly over the years. This failure to address and upgrade our processing of liquid metals is a serious concern, since the principle entrainment defect, the bifilm, is seen as the principle initiator of cracks in metals; in general, bifilms are the Griffith cracks that initiate failures by cracking. A new generation of crack resistant metals and engineering structures can now be envisaged.

  12. Oil ash corrosion

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

  13. Slip-Cast Superconductive Parts

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

    1993-01-01

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

  14. Physicomechanical properties of the surfaces of high-strength cast iron parts subjected to plasma-arc hardening

    Demin, Yu. N.

    2008-12-01

    Plasma-arc treatment is shown to be efficient for increasing the wear and corrosion resistance of high-strength cast iron in contact with quenched steel. Unique experimental techniques are used for estimating the serviceability of parts under conditions of cyclic contact-shear loads.

  15. Environmental degradation of mechanical properties of grey cast iron with different copper contents

    In this work, different percentages of copper were added to grey cast iron to investigate its effect on microstructures, mechanical properties and corrosion behavior of the tested cast iron. Mechanical testing included hardness, tension, compression and impact, while corrosion testing was conducted by immersing specimens in 1 mol HC1 for different exposure times (120, 240, 360, 480, and 600 hrs). It was found that the copper addition had a remarkable effect on graphite morphology, as well as, pearlite and ferrite existing. Copper content proved to affect mechanical properties, improving these properties up to 2%, after which a decrease was noticed. Copper addition has no noticeable effect on percentage tensile strain to fracture, however, it has an obvious effect on the percentage compressive strain to fracture, especially for 2.0 % copper addition. The alloys containing 0.0 % and 1.0 % copper recorded the lower corrosion resistance, while those containing 2.0 % and 4.0 % copper addition gave the higher corrosion resistance. Also, the corrosion rate decreased with the increase of copper content. A change in the angle of fracture in compression was noticed for corroded specimens from about 55 to 90 degrees as exposure time increases. (author)

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

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

    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 ...

  18. Grain boundary corrosion of copper canister weld material

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

  19. Atmospheric corrosion of metals in tropics and subtropic. 2. Corrosion resistance of different metals and alloys

    Data from 169 sources concerning corrosion of different metals, alloys and means of protection, obtained for a 30-year period (up to 1987) in different continent including Europe (Bulgaria, Spain, Italy, France, USSR); America (USA, Panama, Cuba, Venezuela, Brasil, Argentine); Africa (Nigeria, SAR); Australia, New Zeland, Papua-Newguinea, Philippines, are systemized. Actual results of full-scal atmospheric testings of iron, zinc, copper, cadmium, aluminium, tin, lead, carbon, low-alloys. Stainless steels, cast irons, halvanic coatings, copper, aluminium, nickel, titanium, magnesium alloys are presented. Data on the fracture rate can be used for creating the data base in banks on atmospheric resistance of metal materials

  20. Society for Vascular Medicine

    ... Leadership Committees Newsletter Newsletter Archive SVM on Social Media SVM Awards Mission Statement History of SVM Past Presidents Code of Ethics Annual Meeting Events Calendar Vascular Medicine Events Job ...

  1. Diabetes and Vascular Disease

    ... of diabetes-related vascular problems include: Blurred vision Floating spots in your vision Unexpected weight gain or ... tax deductible. 555 Price Ave., Suite 180, Redwood City, CA 94063 This email address is being protected ...

  2. Intracranial Vascular Treatments

    ... Español More Info Images/Videos News Physician Resources Professions Site Index A-Z Intracranial Vascular Treatments Intracranial ... blood pressure and pulse during the procedure. A nurse or technologist will insert an intravenous (IV) line ...

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

    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)

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

    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 α-matrix is more positive than surface potential of β phase.

  5. Digital vascular imaging (DVI)

    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.)

  6. Genetics of Vascular Dementia

    Murray, Melissa E.; Meschia, James F.; Dickson, Dennis W.; Ross, Owen A.

    2010-01-01

    Genetic studies are transforming the way we diagnose, evaluate and treat patients. The era of genome-wide association studies promised to discover common risk variants in heterogeneous disorders where previous small-scale association studies had on the whole failed. However, as we enter the post-association era a degree of disappoint is felt regarding the lack of risk factors with large effect for a number of disorders including vascular disease. Vascular disorders are sporadic by nature, tho...

  7. Monitoring Microbially Influenced Corrosion

    Hilbert, Lisbeth Rischel

    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...... 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...

  8. Corrosion studies on containment materials for vitrified heat generating waste

    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)

  9. Galvanic corrosion behavior of titanium implants coupled to dental alloys.

    Cortada, M; Giner, L; Costa, S; Gil, F J; Rodríguez, D; Planell, J A

    2000-05-01

    The corrosion of five materials for implant suprastructures (cast-titanium, machined-titanium, gold alloy, silver-palladium alloy and chromium-nickel alloy), was investigated in vitro, the materials being galvanically coupled to a titanium implant. Various electrochemical parameters E(CORR), i(CORR) Evans diagrams, polarization resistance and Tafel slopes) were analyzed. The microstructure of the different dental materials was observed before and after corrosion processes by optical and electron microscopy. Besides, the metallic ions released in the saliva environment were quantified during the corrosion process by means of inductively coupled plasma-mass spectrometry technique (ICP-MS). The cast and machined titanium had the most passive current density at a given potential and chromium-nickel alloy had the most active critical current density values. The high gold content alloys have excellent resistance corrosion, although this decreases when the gold content is lower in the alloy. The palladium alloy had a low critical current density due to the presence of gallium in this composition but a selective dissolution of copper-rich phases was observed through energy dispersive X-ray analysis. PMID:15348025

  10. Casting Using A Polystyrene Pattern

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

    1993-01-01

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

  11. The CAST Time Projection Chamber

    Autiero, D; Cébrian, S; Carmona, J M; Chesi, Enrico Guido; Davenport, M; Delattre, M; Di Lella, L; Formenti, F; Gomez, H; Hasinoff, M; Irastorza, I G; Lakic, B; Luzón, G; Morales, J; Musa, L; Ortiz, A; Placci, A; Rodríguez, A; Ruz, J; Villar, J A; Zioutas, K

    2007-01-01

    One of the three X-ray detectors of the CAST experiment searching for solar axions is a Time Projection Chamber (TPC) with a multi-wire proportional counter (MWPC) as a readout structure. Its design has been optimized to provide high sensitivity to the detection of the low intensity X-ray signal expected in the CAST experiment. A low hardware threshold of 0.8 keV is safely set during normal data taking periods, and the overall efficiency for the detection of photons coming from conversion of solar axions is 62 %. Shielding has been installed around the detector, lowering the background level to 4.10 x 10^-5 counts/cm^2/s/keV between 1 and 10 keV. During phase I of the CAST experiment the TPC has provided robust and stable operation, thus contributing with a competitive result to the overall CAST limit on axion-photon coupling and mass.

  12. Niobium in gray cast iron

    The potential for utilization of niobium in gray cast iron is appraised and reviewed. Experiments described in literature indicate that niobium provides structural refinement of the eutectic cells and also promotes pearlite formation. (Author)

  13. Corrosion of metallic materials

    The paper reviews the corrosion of structural materials in water reactors, LMFBR reactors and high temperature reactors (steels, stainless steels and nickel alloys), of fuel cladding for PWR and BWR (zirconium alloys) and in a second part corrosion of stainless steels, titanium and zirconium in reprocessing plants. Corrosion is controlled by modification of the materials or by changing chemical characteristics of the medium and/or physical parameters at the interface. 29 refs

  14. Degradation of trichloronitromethane by iron water main corrosion products.

    Lee, Jeong-Yub; Pearson, Carrie R; Hozalski, Raymond M; Arnold, William A

    2008-04-01

    Halogenated disinfection byproducts (DBPs) may undergo reduction reactions at the corroded pipe wall in drinking water distribution systems consisting of cast or ductile iron pipe. Iron pipe corrosion products were obtained from several locations within two drinking water distribution systems. Crystalline-phase composition of freeze-dried corrosion solids was analyzed using X-ray diffraction, and ferrous and ferric iron contents were determined via multiple extraction methods. Batch experiments demonstrated that trichloronitromethane (TCNM), a non-regulated DBP, is rapidly reduced in the presence of pipe corrosion solids and that dissolved oxygen (DO) slows the reaction. The water-soluble iron content of the pipe solids is the best predictor of TCNM reaction rate constant. These results indicate that highly reactive DBPs that are able to compete with oxygen and residual disinfectant for ferrous iron may be attenuated via abiotic reduction in drinking water distribution systems. PMID:18207489

  15. Colour Metallography of Cast Iron

    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 ...

  16. Corrosion control. 2. ed.

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

  17. Virtualisation of casting engineering

    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

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

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

  19. Inoculation of chromium white cast iron

    D. Kopyciński

    2009-01-01

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

  20. Inoculation of chromium white cast iron

    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.

  1. Geometric aspects of the casting process

    Ahn, H.-K.

    2002-01-01

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

  2. Copper alloys in investment casting technology

    S. Rzadkosz; Zych, J; Garbacz-Klempka, A.; Kranc, M.; J. Kozana; Piękoś, M.; J. Kolczyk; Jamrozowicz, Ł.; Stolarczyk, T.

    2015-01-01

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

  3. Microvascularization on collared peccary placenta: a microvascular cast study [corrected] in late pregnancy.

    Santos, Tatiana Carlesso; Oliveira, Moacir Franco; Dantzer, Vibeke; Miglino, Maria Angélica

    2012-07-01

    The microvascularization of the collared peccary (Tayassu tajacu) placenta was studied by vascular casts and immunolocalization of α-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. PMID:22775252

  4. Formation Mechanism of Discoloration on Die-Cast AZ91D Components Surface After Chemical Conversion

    Liu, Bao-sheng; Wei, Ying-hui; Hou, Li-feng

    2013-01-01

    A notebook (NB) computer component was manufactured from AZ91D Mg alloy by a die-casting process. After chemical conversion treatment, a discoloration was noted on the component surface. The source of this discoloration has been studied in detail by scanning electron microscopy, energy dispersive spectroscopy, and spark atomic absorption spectroscopy. The corrosion resistance was also measured by potentiodynamic polarization, hydrogen evolution and salt spray testing. The formation mechanism for the discoloration which was caused by the residue left behind by excess mold release agent sprayed during the die-casting was discussed in detail. After chemical conversion treatment, the residual-baked mold release agent was apparent on the component surface as "white ash." Consequently, it degraded seriously both the appearance and the corrosion resistance of the manufactured component.

  5. A study on phase stress of centrifugally cast duplex stainless steel by neutron diffraction

    With great corrosion resistance and mechanical property, ferrite-austenitic duplex stainless steel have been applied to components in corrosive environments such as sea water pumps. Due to different coefficients of thermal expansion and elastic modulus between the two phases, phase stress occurs after heat treatment or material processing such as casting, forging and machining, which may affect material properties such as fatigue strength, welding stability and so on. In this study, phase stress distribution along thickness direction of duplex stainless steel hollow cylinders fabricated by centrifugal casting was measured by pulsed neutron diffraction using time-of-flight (TOF) method. Also lattice strain and phase stress evolution were discussed by in-situ neutron diffraction measurement during tensile test. All these measurements were conducted at Japan Proton Accelerator Research Complex (J-PARC). (author)

  6. Corrosion in the oil industry

    Brondel, D. (Sedco Forex, Montrouge (France)); Edwards, R. (Schlumberger Well Services, Columbus, OH (United States)); Hayman, A. (Etudes et Productions Schlumberger, Clamart (France)); Hill, D. (Schlumberger Dowell, Tulsa, OK (United States)); Mehta, S. (Schlumberger Dowell, St. Austell (United Kingdom)); Semerad, T. (Mobil Oil Indonesia, Inc., Sumatra (Indonesia))

    1994-04-01

    Corrosion costs the oil industry billions of dollars a year, a fact that makes the role of the corrosion engineer an increasingly important one. Attention is paid to how corrosion affects every aspect of exploration and production, from offshore rigs to casing. Also the role of corrosion agents such as drilling and production fluids is reviewed. Methods of control and techniques to monitor corrosion are discussed, along with an explanation of the chemical causes of corrosion. 21 figs., 32 refs.

  7. Corrosion of proposed canister materials in salt repositories

    Research at Sandia is focusing on TiCode-12 (Ti-0.3Mo-0.8Ni) as a corrosion resistant alloy for fabricating canister overpacks, and possibly the canisters themselves. Tests involving the straining of this alloy at applied anodic overpotentials in brine showed that it does not stress corrode. If hydrogen is introduced, either by cathodic polarization in brine or by electrochemically charging prior to testing, embrittlement can occur. Results from gas-charged specimens indicate that noticeable embrittlement occurs at hydrogen concentrations above about 400 wppm. Pitting was not observed after experiments involving exposure of coupons for several weeks to neutral brine at temperatures up to 2000C. It did occur during two test involving brine previously acidified to pH 2, and then only under adherent salt deposits that develop during the tests. These conditions of low pH and adherent salt layer represent an overtest, and pitting is not anticipated in a salt repository. The effects of Ni and Mo alloy additions on the electrochemistry of corrosion of TiCode-12 were characterized. The uniform corrosion rates of Ni, Fe, and Ti-based alloys that are being considered as alternate, or backup materials to Ticode-12, were measured in brine. No localized corrosion occurred, and the rates of uniform attack of the Ni and other Ti-base alloys were sufficiently low to qualify them as alternate alloys to TiCode-12. The corrosion rate of cast iron in deaerated brine was 0.13 mm/yr, indicating that cast iron is a corrosion allowance material for potential use in canister. 10 references, 7 figures, 1 table

  8. Corrosion of proposed canister materials in salt repositories

    Research at Sandia is focussing on Ti-Code-12 (Ti-0.3Mo-0.8Ni) as a corrosion resistant alloy for fabricating canister overpacks, and possibly the canisters themselves. Tests involving the straining of this alloy at applied anodic overpotentials in brine showed that it does not stress corrode. If hydrogen is introduced, either by cathodic polarization in brine or by electrochemically charging prior to testing, embrittlement can occur. Results from gas-charged specimens indicate that noticeable embrittlement occurs at hydrogen concentration above about 400 wppm. Pitting was not observed after experiments involving exposure of coupons for several weeks to neutral brine at temperatures up to 2000C. It did occur during two tests involving brine previously acidified to pH 2, and then only under adherent salt deposits that developed during the tests. These conditions of low pH and adherent salt layer represent an overtest, and pitting is not anticipated in a salt repository. The effects of Ni and Mo alloy additions on the electrochemistry of corrosion of Ti-Code-12 were characterized. The uniform corrosion rates of Ni, Fe, and Ti-based alloys that are being considered as alternate, or backup materials to Ti-Code-12, were measured in brine. No localized corrosion occurred, and the rates of uniform attack of the Ni and other Ti-base alloys were sufficiently low to qualify them analternate alloys to Ti-Code-12. The corrosion rate of cast iron in deaerated brine was 0.13 mm/yr, indicating that cast iron is a corrosion allowance material for potential use in canisters

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

    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)

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

    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 (~ 0,050,12 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.

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

    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...

  12. Al-Si Cast Alloys - Microstructure and Mechanical Properties at Ambient and Elevated Temperature

    Zamani, Mohammadreza

    2015-01-01

    Aluminium alloys with Si as the major alloying element form a class of material providing the most significant part of all casting manufactured materials. These alloys have a wide range of applications in the automotive and aerospace industries due to an excellent combination of castability and mechanical properties, as well as good corrosion resistance and wear resistivity. Additions of minor alloying elements such as Cu and Mg improve the mechanical properties and make the alloy responsive ...

  13. Relationships between microstructure and mechanical properties in ductile cast irons: a review

    The progress achieved in the understanding of the relationships between the microstructure and the mechanical properties of ductile cast iron is reviewed. It is also described the applications of heat treatment of austempered to ductile irons (ADI), which have allowed to improve substantially the mechanical properties of these materials. It is proposed a research program to obtain the crack growth resistance under corrosive atmospheres and to model the mechanical properties. (Author) 83 refs

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

    Voleník, Karel; Schneeweiss, Oldřich; Chráska, Tomáš; Dubský, Jiří; Písačka, Jan

    2009-01-01

    Roč. 47, č. 1 (2009), s. 19-24. ISSN 0023-432X R&D Projects: GA AV ČR 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

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

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

    2015-11-01

    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 α-Mg matrix and the correspondingly reduced presence of the β-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 <0.4 mm/year compared with ∼2 mm/year for the conventionally cast alloy and 26 mm/year for the rapidly solidified extruded ribbons. PMID:25491147

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

    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.

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

    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

  18. Research on the squeeze cast technology of the castings with large ratio of height to thickness

    Li, Chen-Xi; SAN Jing-chao; Xu, Na

    2005-01-01

    The squeeze cast technology is only applicable, at present, to the castings with a ratio of height to thickness less than 3.5. Researching the squeeze cast technology for castings with a large ratio of height to thickness will broaden the applicable range of the advanced casting technology. This paper describes a study of the temperature distribution during solidification for castings with a ratio of height to thickness of 7 by the methods of experiment and computer simulation. The shrinkage ...

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

    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

  20. Archaeological analogs and corrosion

    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.)

  1. Corrosion evaluation technology

    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.

  2. Corrosion in power engineering

    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.)

  3. Bacterial corrosion of metals

    Two approaches exist to deal with the questions of bacterial corrosion of metals: the first one reveals the microbiological effects of bacterial corrosion and the second one tries to determine the action mechanisms due to such or such metallic alloy category. This second approach is particularly developed considering the cases of carbon steels, stainless steels, copper alloys and light alloys. (O.M.)

  4. Demystifying Controlling Copper Corrosion

    The LCR systematically misses the highest health and corrosion risk sites for copper. Additionally, there are growing concerns for WWTP copper in sludges and discharge levels. There are many corrosion control differences between copper and lead. This talk explains the sometimes c...

  5. Corrosion evaluation technology

    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

  6. SCHEDULED CASTE FARMERS: A SOCIOLOGICAL STUDY

    Shekhara Apparaya

    2015-04-01

    Full Text Available Scheduled castes are backward castes in Hyderabad-Karnataka region. As such, farmers belonged to scheduled castes are poor and facing many of the social problems in society. To explore the problems of scheduled caste farmers, the present interview based survey was made in Aland taluka of Kalaburagi district. Totally 400 scheduled caste farmers were surveyed to collect the primary data. It is highlighted from the study that the scheduled caste farmers are facing many problems due to their castes and poverty. Though welfare schemes are formulated for their development, the farmers were not gained benefits from these schemes and lack of awareness is the major reasons for not gaining such benefits. Hence, it is essential to increase awareness about farmers’ and scheduled caste welfare schemes among the scheduled caste farmers.

  7. Fillability of Thin-Wall Steel Castings

    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.

  8. Long-term corrosion behavior of cathodicly protected cask materials

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

  9. Characterization Studies of Mullite Coatings on Cast Aluminum

    Viswanath, B.; Vijayarangan, S.

    2012-03-01

    Thermal barrier coating of mullite was plasma sprayed on cast aluminum A 356.0, in the T6 condition (solution treated, quenched and artificially aged) for use in internal combustion engine applications. This study pertains to the mechanical, thermal, wear, corrosion and micro structural characterization of the coating. An average coating tensile strength of 50 MPa and average adhesive bond strength of 20 MPa was measured in the mechanical tests. A wear factor of 0.7 10-3 mg/Nm was measured in the wear studies using a pin on disk apparatus. An average value of 0.151 W/m K was measured in the thermal conductivity test. The coating withstood 100 cycles in the thermal shock test, without any sign of spallation. Corrosion tests showed no signs of corrosion even after 500 h. The microstructural and porosity studies were conducted using an optical microscope and scanning electron microscope with an energy dispersive spectroscopy (EDS) attachment. The studies revealed a crystalline microstructure of the substrate, which correspond to the splat structure of the coating. The porosity of the coated layers ranged from 6 to 21% by volume, at an average of 12-16%. EDS studies showed the elements present in the coating. X-ray diffraction patterns taken on coated specimens, showed the phases present in the coating, and indicated a crystalline structure of the coating along with some amorphous matter.

  10. Microstructure, mechanical performance and corrosion properties of base metal solder joints

    Sujesh Machha

    2011-01-01

    Full Text Available Context: Alloys have been considered to be of paramount importance in the field of prosthodontics. Long span prosthesis may often require joining of one or more individual castings to obtain better fit, occlusal harmony and esthetics in comparison to one-piece casting. Aim: This study was undertaken to evaluate the mechanical properties of base metal alloys joined by two different techniques, namely, gas oxygen torch soldering and laser fusion, compared to a one-piece casting. Mechanical properties evaluated were tensile strength, percentage of elongation and hardness of the solder joint. In addition, corrosion properties and scanning electron microscopic appearance of the joints were also evaluated. Materials and Methods: The samples were prepared according to American Society for Testing Materials specifications (ASTM, E8. Specimens were made with self-cure acrylic and then invested in phosphate-bonded investment material. Casting was done in induction casting machine. Thirty specimens were thus prepared for each group and compared with 30 specimens of the one-piece casting group. Statistical Analysis Used: SPSS software (version 10.0, Chicago, IL, USA was used for statistical analysis. ANOVA and Benferroni post hoc tests were done for multiple comparisons between the groups and within the groups for mean difference and standard error. Results: Results showed that tensile strength of the one-piece casting was higher than laser fused and gas oxygen torch soldered joints. Laser fused joints exhibited higher hardness values compared to that of gas oxygen torch soldered joints. Scanning electron microscopic examination revealed greater porosity in the gas oxygen torch soldered joints. This contributed to the reduction in the strength of the joint. Gas oxygen torch soldered joints showed less corrosion resistance when compared to laser fused joints and one-piece casting. Conclusion: Laser fusion, which is a recent introduction to the field of prosthodontics, produces joints which have properties between those of one-piece casting and the gas oxygen torch soldering.

  11. Corrosion fatigue of steels

    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.)

  12. Corrosion in methylphosphonic difluoride

    Zabielski, C.V.; Levy, M. (Army Research Lab., Watertown, MA (United States))

    1994-12-01

    Electrochemical potentiodynamic polarization studies were conducted for a variety of ferrous and nonferrous metals in methylphosphonic difluoride. Studies were also made of the effects of organic inhibitors on the corrosion rates of 1,020 steel, type 316L, and type 304 stainless steel, and magnesium in methylphosphonic difluoride. Chemical weapons in the US include binary munitions in which two components are kept in separate compartments until activation. These munitions must be stockpiled for long periods of time (up to 30 years) and then must operate reliably when the need arises. The principal cause of failure will be corrosion of the storage container by the highly corrosive methylphosphonic difluoride (DF). The objectives of this study were to: investigate the kinetics and mechanisms of corrosion of Al 6061-T6 and candidate metal alloys in DF; establish effective corrosion inhibitors; and ultimately incorporate or immobilize inhibitors into coatings that provide protection above the liquid line.

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

    Pease, Bradley Justin; Geiker, Mette Rica; Stang, Henrik; Weiss, W. Jason

    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...... 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...

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

    Mareci, Daniel; Bolat, Georgiana [Technical Univ. Iasi (Romania). Faculty of Chemical Engineering and Environmental Protection; Strugaru, Sorin Iacob; Munteanu, Corneliu [Technical Univ. Iasi (Romania). Faculty of Mechanical Engineering; Souto, Ricardo M. [Univ. of La Laguna, Tenerife (Spain). Dept. of Chemistry

    2015-03-15

    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.

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

    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.

  16. Cast adrift: Gortex cast liners allow greater patient activity.

    Dubowitz, Gerald; Miller, Deborah M

    2003-01-01

    Extremity fractures are a common injury, with nearly 1.5 million cases reported in the United States in 1998. Treatment often involves lengthy periods of immobilization. This report outlines the use of a Gortex cast liner by a subject who was able to engage in swimming and scuba diving during the healing process. We report that a Gortex cast liner may be considered for an active patient who is keen to return to limited activities during fracture healing. Apparently because of a lack of knowledge of their existence, physicians currently are underutilizing this method of casting in active patients. The use of Gortex liners elsewhere has been reported to have higher patient and physician satisfaction in both use and performance, with no reported detrimental effects on outcome. PMID:14518627

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

    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.

  18. Aluminide protective coatings on high–temperature creep resistant cast steel

    J. Kubicki

    2009-10-01

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

  19. Development of vascular radiology

    The problems of vascular radiology may be resumed in terms of: quality of image up to the tertiary branches of the arteries, considerations of examination speed, dose and injected volume. Three vascular mountings are therefore presented including one, especially original, for two-plane cardiovascular exploration. The generator and auxiliary equipment: luminance amplifiers, television unit, add automation and image quality control to these systems. In a field where the problems of dose might be eclipsed by the importance of the examination, equipment to reduce dose is presented. The two-plane mounting ANGIOMAX also enables the volume of opacifier to be decreased, helping to improve the quality of the image

  20. Endoluminal vascular prostheses

    Endoluminal vascular prostheses that can be implanted by percutaneous routes represent the most recent development in vascular interventional radiology. Various commercially available types of prosthesis are presented and the construction principles and applications are described. At present secure indications for the implantation of endoluminal prostheses are limited to the elimination of aneurysms and arteriovenous fistulae of the large vessels near the trunk in sections that do not cross a joint. The wide use in peripheral occlusive diseases cannot yet be recommended because confirmed data are not available. (orig.)

  1. Vascular graft infections.

    Young, Michael H; Upchurch, Gilbert R; Malani, Preeti N

    2012-03-01

    Prosthetic vascular grafting is a commonly performed procedure that is central to the management of arterial disease and renal failure. Though rare, vascular graft infections (VGI) are potentially devastating, and carry a high rate of mortality and amputation. Despite extensive research and clinical experience, VGI remain a daunting therapeutic challenge for surgeons and infectious disease specialists. This article reviews the pathogenesis of VGI, in particular the role of biofilms, as well as the current state of clinical management including diagnostic modalities, surgical options for treatment, antimicrobial therapy, and preventive measures. PMID:22284375

  2. Thermal analysis thermal of continuous casting equipment

    Shin, Y. J.; Lee, J. C.; Lee, Y. S. [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2000-03-01

    Thermal analysis of continuous casting equipment has been carried out to calculate the temperature and solidification profiles. Fluid flow and heat transfer analysis model including the effects of phase change was used to simulate the continuous casting process by finite volume method. In the design of continuous casting equipment, the casting speed, pouring temperature and cooling conditions should be considered as significant factors. In this study, the effects of casting speed, pouring temperature, and air gap between the uranium and mold were investigated. The results obtained from this study will be applied as a basic data for design, fabrication and casting test. 8 refs., 8 figs., 2 tabs. (Author)

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

    Hilbert, Lisbeth Rischel

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

  4. Improved corrosion resistance of a high-strength MgAlMnCa magnesium alloy made by rapid solidification powder metallurgy

    Highlights: ? Corrosion behavior of an MgAlMnCa 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 MgAlMnCa 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 such as SWAP.

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

    A. Kiełbus

    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 α-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 α-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.

  6. Research on the squeeze cast technology of the castings with large ratio of height to thickness

    LI Chen-xi

    2005-11-01

    Full Text Available The squeeze cast technology is only applicable, at present, to the castings with a ratio of height to thickness less than 3.5. Researching the squeeze cast technology for castings with a large ratio of height to thickness will broaden the applicable range of the advanced casting technology. This paper describes a study of the temperature distribution during solidification for castings with a ratio of height to thickness of 7 by the methods of experiment and computer simulation. The shrinkage porosity distribution in the castings and the mechanical properties of the castings were also researched. The experimental and simulated results show that increasing squeeze force, or enhancing mold temperature,cannot reduce the shrinkage porosities in the castings. When castings solidify in a sequential manner and the squeeze force effectively acts on the surface of the liquid metal, the shrinkage porosities in the castings are eliminated and mechanical properties are clearly improved.

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

    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 prefabrication of axial vascularized coral bone is superior as vascular carrier.

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

    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.

  9. Centrifugal slip casting of components

    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

  10. Mitigation of Corrosion on Magnesium Alloy by Predesigned Surface Corrosion

    Xuming Zhang; Guosong Wu; Xiang Peng; Limin Li; Hongqing Feng; Biao Gao; Kaifu Huo; Chu, Paul K

    2015-01-01

    Rapid corrosion of magnesium alloys is undesirable in structural and biomedical applications and a general way to control corrosion is to form a surface barrier layer isolating the bulk materials from the external environment. Herein, based on the insights gained from the anticorrosion behavior of corrosion products, a special way to mitigate aqueous corrosion is described. The concept is based on pre-corrosion by a hydrothermal treatment of Al-enriched Mg alloys in water. A uniform surface c...

  11. Corrosion Inhibitors for Reinforced Concrete

    ECT Team, Purdue

    2007-01-01

    Steel corrosion in reinforced concrete structures has been a major problem across the U.S. Steel-reinforced concrete structures are continually subject to attack by corrosion brought on by naturally occurring environmental conditions. FerroGard, a corrosion inhibitor, developed by Sika Corporation, penetrates hardened concrete to dramatically reduce corrosion by 65% and extend the structure's service life.

  12. Corrosion Failures in Marine Environment

    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.

  13. Automated Methods Of Corrosion Measurements

    Bech-Nielsen, Gregers; Andersen, Jens Enevold Thaulov; Reeve, John Ch; Nielsen, Lars Vendelbo; Bisgård, Anne D.

    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.......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....

  14. Engineered Vascularized Muscle Flap.

    Egozi, Dana; Shandalov, Yulia; Freiman, Alina; Rosenfeld, Dekel; Ben-Shimol, David; Levenberg, Shulamit

    2016-01-01

    One of the main factors limiting the thickness of a tissue construct and its consequential viability and applicability in vivo, is the control of oxygen supply to the cell microenvironment, as passive diffusion is limited to a very thin layer. Although various materials have been described to restore the integrity of full-thickness defects of the abdominal wall, no material has yet proved to be optimal, due to low graft vascularization, tissue rejection, infection, or inadequate mechanical properties. This protocol describes a means of engineering a fully vascularized flap, with a thickness relevant for muscle tissue reconstruction. Cell-embedded poly L-lactic acid/poly lactic-co-glycolic acid constructs are implanted around the mouse femoral artery and vein and maintained in vivo for a period of one or two weeks. The vascularized graft is then transferred as a flap towards a full thickness defect made in the abdomen. This technique replaces the need for autologous tissue sacrifications and may enable the use of in vitro engineered vascularized flaps in many surgical applications. PMID:26779840

  15. Spinal vascular malformations

    Spinal vascular malformations are a group of rare diseases with different clinical presentations ranging from incidental asymptomatic findings to progressive tetraplegia. This article provides an overview about imaging features as well as clinical and therapeutic aspects of spinal arteriovenous malformations, cavernomas and capillary telangiectasia. (orig.)

  16. Renal posttransplant's vascular complications

    Bai? 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].

  17. Some effects of aqueous silica on the corrosion of iron.

    Rushing, Jason C; McNeill, Laurie S; Edwards, Marc

    2003-03-01

    Silica is an important natural component of ground and surface waters, and is sometimes added as an inhibitor to control "red water" problems caused by corroding iron pipes. However, the effect of silicates on many aspects of iron corrosion has never been assessed. Experiments with water containing 0.5, 10, 25 or 50mg/L of SiO(2) demonstrated a significant interplay between aqueous silica and iron corrosion. During this 4-month experiment, higher levels of silica caused more iron release to the water and decreased the size of suspended iron particles. The process of iron corrosion also changed aqueous silica concentrations; silica was released into the water from the cast iron during corrosion and was removed from the water by incorporation into the scale layer. Silica also affected the type of scale that formed on the iron coupons. Scale at the lower silica concentrations was fairly uniform and easy to remove from the coupons, while the scale from the high silica reactors was more dense, and was more difficult to remove. Scale from the high concentration silica reactor also developed tall tubercles, and hydrogen gas-containing bubbles were channeled to solution through these tubercles. Iron corrosion occurring via the evolution was significant under all experimental conditions. PMID:12553983

  18. Secondary dendrite arm spacing and solute redistribution effects on the corrosion resistance of Al-10 wt% Sn and Al-20 wt% Zn alloys

    In general, aluminum alloys provide the most significant part of all shaped casting manufactured. An optimum range of properties can be obtained as a function of different cooling rate processes, such as sand, plaster, investment, permanent molds and die castings. It is well known that the dendritic network affects not only the mechanical properties but also the corrosion resistance. However, the literature is scarce on reports concerning the influences of dendrite arm spacing on corrosion resistance and mechanical behavior. The aim of this study is to investigate the influence of as-cast microstructure features, i.e., dendrite arm spacing and solute redistribution on the corrosion resistance of samples of aluminum alloys. In order to investigate the electrochemical behavior of solute and solvent of different aluminum systems, samples with the same order of magnitude of dendritic spacings were analyzed to permit comparison between Al-10 wt% Sn and Al-20 wt% Zn alloys. A casting water-cooled assembly promoting upward directional solidification was used in order to obtain controlled casting samples of these alloys. In order to characterize the dendritic structure, longitudinal sections from the directionally solidified specimens were analyzed by using optical and electronic microscopy techniques. The corrosion resistance was analyzed by both the electrochemical impedance spectroscopy technique and Tafel extrapolation method conducted in a 3% NaCl solution at room temperature. Although both systems present an Al-rich dendritic matrix, different responses to corrosive action as a function of dendritic spacing have been detected

  19. The Corrosion and Preservation of Iron Antiques.

    Walker, Robert

    1982-01-01

    Discusses general corrosion reactions (iron to rust), including corrosion of iron, sulfur dioxide, chlorides, immersed corrosion, and underground corrosion. Also discusses corrosion inhibition, including corrosion inhibitors (anodic, cathodic, mixed, organic); safe/dangerous inhibitors; and corrosion/inhibition in concrete/marble, showcases/boxes,…

  20. Irritants and corrosives.

    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

  1. Archaeological analogues and corrosion

    One solution retained for the management of high-level and long living radioactive wastes is the disposal in deep underground. Among the studies carried out by the Andra for the evaluation this solution, one concerns the research on metals corrosion for the development of reliable containers. Laboratory corrosion tests are in progress and are compared to the corrosion state of archaeological metal specimens of several hundred years old. Gallic or Mesopotamian remnants are some of these archaeological analogues which are analyzed using the most advanced techniques of materials science. (J.S.)

  2. Corrosion of reactor materials

    Corrosion resistance of stainless and pearlitic steels, zirconium alloys and steels in liquid metal coolants under conditions of nuclear power generating facilities operation has been considered at up-to-date scientific level. Quantitative dependences permitting prediction of the influence of operation conditions (medium composition, temperature, mechanical stresses, irradiation) on general and local corrosion resistance of the reactor materials are given. The theoretical concepts elaborated permit a quantitative evaluation of the influence of corrosive medium and operational conditions on service life of equipment in nuclear power generating facilities. 70 refs., 1 fig., 36 tabs

  3. Elucidating Sweet Corrosion Scales

    Joshi, Gaurav Ravindra

    2015-01-01

    The objective of this thesis is to improve understanding of the development of corrosion products (scales) that form on the inner walls of carbon steel pipelines in CO2-rich (sweet) oilfield environments. If well adherent to the carbon steel surface, such scales can significantly reduce the metal’s rate of corrosion. Typically, the open literature labels sweet corrosion scale as ferrous (II) carbonate (FeCO3) or siderite, although this may not always be the case. For example, Fe2(OH)2CO3 (chu...

  4. Corrosion-resistant uranium

    The present invention is directed to the protecting of uranium and uranium alloy articles from corrosion by providing the surfaces of the articles with a layer of an ion-plated metal selected from aluminum and zinc to a thickness of at least 60 microinches and then converting at least the outer surface of the ion-plated layer of aluminum or zinc to aluminum chromate or zinc chromate. This conversion of the aluminum or zinc to the chromate form considerably enhances the corrosion resistance of the ion plating so as to effectively protect the coated article from corrosion

  5. Microbiologically influenced corrosion testing

    This symposium was held November 16--17, 1992 in Miami, Florida. The purpose of the symposium was to provide a forum for state-of-the-art information on the effects of microorganisms on the corrosion of metals. Many industrial needs in the area of microbial influenced corrosion testing are identified in the presentations along with latest laboratory and field testing techniques. Strategies to monitor and control corrosion and biofouling in water distribution systems, underground pipelines, buildings, and marine vessels are discussed. Individual papers have been processed separately for inclusion in the appropriate data bases

  6. Static corrosion of construction materials exposed to superphosphoric acid made from various sources of phosphate rock

    Nguyen, D.T.; McDonald, C.L.; McGill, K.E.

    1994-10-01

    Corrosion tests were performed with various construction materials, such as carbon steel, cast iron, stainless steels, nickel and nickel-based alloys, copper and its alloys, aluminum alloy, zirconium alloy, and tantalum, exposed to wet-process superphosphoric acids (approximately 70% P{sub 2}O{sub 5}) from all the suppliers in the United States and to a technical-grade (55% P{sub 2}O{sub 5}) acid made by the electric furnace process. The study was conducted in response to reports from pipe-reactor users of excessive corrosion by superphosphoric acids and electric furnace acid. Test temperatures were ambient (approximately 21{degrees}C or 70{degrees}F), 66{degrees}C (150{degrees}F), and 93{degrees}C (200{degrees}F). Test results showed that temperature was a significant factor in acid corrosivity. Electric furnace acid was more corrosive than the superphosphoric acids. Carbon steel, cast iron, and aluminum alloy were not resistant to either the superphosphoric acids or the electric furnace acid. Nickel-chromium (Ni-Cr) and nickel-molybdenum (Ni-Mo) based alloys and tantalum exhibited adequate corrosion resistance in the superphosphoric acids and the electric furnace acid. Stainless steels performed well in all test acids at all test temperatures with some exceptions in the electric furnace acid at 93{degrees}C. Zirconium alloy, copper and its alloys, pure nickel, and Monel 400 provided adequate corrosion resistance to all test acids at ambient temperature only.

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

    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)

  8. SE 10-08 Oceanographic: XBT Casts

    National Oceanic and Atmospheric Administration, Department of Commerce XBT casts were conducted four times each day (morning, midday, afternoon, evening)along the survey tracklines within the Hawaii EEZ. If a CTD cast could not be...

  9. SE 11-08 Oceanographic: CTD Casts

    National Oceanic and Atmospheric Administration, Department of Commerce CTD casts were conducted twice daily (prior to sunrise and after sunset) along the survey trackline. The terminal depth of all casts was 1000 m.

  10. SE 13-03 Oceanographic: CTD Casts

    National Oceanic and Atmospheric Administration, Department of Commerce — CTD casts were conducted twice daily (prior to sunrise and after sunset) along the survey trackline. The terminal depth of all casts was 1000 m.

  11. Pipe Lines – External Corrosion

    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...

  12. Modeling of feeding of grey iron castings

    M. Perzyk; T. Gontarski

    2011-01-01

    The aim of the paper was development and testing a new methodology for adjusting of simulation parameters of casting processes. Instead using production castings with limited shapes, the methodology utilizes especially designed virtual castings of arbitrary geometries, with rigging systems calculated according generally approved principles, based on industrial experience. The present work tests included risers for grey iron castings, designed according Karsays recommendations; the simulation...

  13. Developing technological process of obtaining giality casts

    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.

  14. Advanced casting technologies for lightweight automotive applications

    Alan A. Luo; Anil K. Sachdev; Bob R. Powell

    2010-01-01

    This paper provides an overview of alloy and process developments in aluminum and magnesium castings for lightweight automotive applications. Wear-resistant aluminum alloys, creep-resistant and high strength/ductility magnesium alloys have been developed for automotive applications. On the process front, vacuum-assisted die casting and high vacuum die casting technologies have been developed for high-integrity body and chassis applications. Thin-wall and hollow casting components are being pr...

  15. Panel report on corrosion in energy systems

    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

  16. Experimental and mechanism research of SO(2) removal by cast iron scraps in a magnetically fixed bed.

    Jiang, Ju-Hui; Li, Ya-Hong; Cai, Wei-Min

    2008-05-01

    Sulfur dioxide can be effectively removed by cast iron scraps corrosion process in a DC magnetically fixed bed, and iron sulfate compounds are gained as an available byproduct. At approximate 50 degrees C, when magnetic field intensity was at 15 mT and height of scraps was about 25 mm, the SO(2) removal efficiency can be kept above 80%. As the deposited rusts accumulated, the corrosion rate and desulfurization efficiency gradually decreased. The results show SO(2) removal efficiency depends on corrosion rate, and it can be obviously enhanced by DC magnetic field. With the XRD and SEM research, it can be found that DC magnetic field cannot change the crystal structure of rusts, but can make the surface morphologies on the surface of scraps looser which means easily to be removed. Consequently, the corrosion resistance can be lessened and SO(2) removal efficiency is improved significantly. PMID:17920766

  17. Growth inhibition of cultured smooth muscle cells by corrosion products of 316 L stainless steel wire.

    Shih, C C; Shih, C M; Chen, Y L; Su, Y Y; Shih, J S; Kwok, C F; Lin, S J

    2001-11-01

    The potential cytotoxicity on vascular smooth muscle cells of corrosion products from 316 L stainless steel, one of most popular biomaterials of intravascular stents, has not been highlighted. In this investigation, 316 L stainless steel wires were corroded in Dulbecco's modified eagle's medium with applied constant electrochemical breakdown voltage, and the supernatant and precipitates of corrosion products were prepared as culture media. The effects of different concentrations of corrosion products on the growth of rat aortic smooth muscle cells were conducted with the [3H]-thymidine uptake test and cell cycle sorter. Both the supernatant and precipitates of corrosion products were toxic to the primary culture of smooth muscle cells. The growth inhibition was correlated well with the increased nickel ions in the corrosion products when nickel concentration was above 11.7 ppm. The corrosion products also changed cell morphology and induced cell necrosis. The cell growth inhibition occurred at the G0/G1 to S transition phase. Similar to our recent study of nitinol stent wire, the present investigation also demonstrated the cytotoxicity of corrosion products of 316 L stainless steel stent wire on smooth muscle cells, which might affect the poststenting vascular response. PMID:11484182

  18. Corrosion Inhibitors for Aluminum.

    Muller, Bodo

    1995-01-01

    Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)

  19. Effective corrosion protection

    The following methods have been developed to minimize corrosion in conventional and nuclear power plants, heating station equipment, and other heat generating installations and district heat distribution grids: (1) chemical cleaning of steam and water boilers by using a special active agent which forms compounds with multivalent metal ions and dissolves already existing deposits on the wall, (2) corrosion protection of steam and hot water boilers of all systems and types during shut down by the use of a film-forming substance, and (3) corrosion protection of warm and hot water grids during operation or shut down by introducing a corrosion inhibitor which forms a protective film on all metal surfaces upon which the warm or hot water impinges during routine operation. The technical and economical advantages of the methods are summarized

  20. Palaeoceanography: Corrosive circulation

    Schaller, Morgan F.

    2015-06-01

    An ancient carbon release resulted in widespread dissolution of carbonates at the sea floor. Numerical simulations suggest that the pattern of dissolution can be explained by a top-down invasion of corrosive bottom waters from the North Atlantic.