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1

High-resolution imaging of kidney vascular corrosion casts with Nano-CT.  

Science.gov (United States)

A vascular corrosion cast of an entire mouse kidney was scanned with a modular multiresolution X-ray nanotomography system. Using an isotropic voxel pitch of 0.5 ?m, capillary systems such as the vasa recta, peritubular capillaries and glomeruli were clearly resolved. This represents a considerable improvement over corrosion casts scanned with microcomputed tomography systems. The resolving power of this system was clearly demonstrated by the unique observation of a dense, subcapsular mat of capillaries enveloping the entire outer surface of the cortical region. Resolution of glomerular capillaries was comparable to similar models derived from laser scanning confocal microscopy. The high-resolution, large field of view and the three-dimensional nature of the resulting data opens new possibilities for the use of corrosion casting in research. PMID:21122193

Wagner, Roger; Van Loo, Denis; Hossler, Fred; Czymmek, Kirk; Pauwels, Elin; Van Hoorebeke, Luc

2011-04-01

2

Study of vascular pattern in human spleen by corrosion cast method  

Directory of Open Access Journals (Sweden)

Full Text Available Background: The aim of the present work was to study the parenchymal distribution of the splenic artery and clarify the avascular planes in human spleens. Observation: Splenic vascular pattern was studied in fifty human spleens, Cellulose Acetate Moulding Granules were used as casting media, injected in the splenic trunk .Soft tissue corrosion was done in the concentrated Potassium Hydroxide and the pattern was studied from obtained cast. Number of segments varied from two to five based on the observation of the terminal and polar splenic branches by corrosion cast and taking account of the ideas ,reported in the literature ,proposed that the spleen is divided in arterial segments and sub segments. Primary segments are territories corresponding to primary branches and polar segments corresponding to polar arteries. Result: There were two primary segments in 90% spleens and three primary segments in 10% spleens. Associate to that in 32% spleens there was superior polar segments, in 56% inferior polar segments and in 12.4% both superior and inferior polar segments. Conclusion: Maximum number of spleens were divided into two lobes and less number of spleens were divided into three lobes, along with that additional lobes were also present when additional arteries present.

Shashikala R. Londhe

2013-04-01

3

Microvasculature of the cerebral cortex: a vascular corrosion cast and immunocytochemical study.  

Science.gov (United States)

In mammals, the cerebral cortex microvasculature (CCM) of the neopallium plays important roles in the physiological and pathological processes of the brain. The aim of the present work is to analyze the CCM by use of the SEM-vascular corrosion cast technique, and to examine the immunocytochemical characteristics of the CCM in adult domestic ruminants (cattle, buffalo, and sheep) by using the SEM-immunogold technique. The CCM originated from the very small, finger-like terminal branches of the macrovasculature of the brain. The superficial cortical arterioles were more numerous than the deep straight arterioles which proceeded toward the white matter. The surface casts of the arterioles and capillaries of the cerebral cortex showed ring-shaped formations in the arterioles and at the origin of the capillaries. All capillaries down-stream from these ring-shaped formations were flaccid. Casts of the capillaries showed wrinkles due to the presence of endothelial folds, which is characteristic of varying blood pressure. Formations having intense anti-GIFAP immunoreactivity were frequently evident along the course of the blood capillaries in the cerebral cortex. These formations were probably astrocytes that might regulate the cerebral microcirculation based on physiological and pathological stimuli, such as neuronal activation. PMID:24458766

Scala, Gaetano

2014-04-01

4

The microvasculature of the lateral choroid plexus in the rat: a scanning electron microscopy study of vascular corrosion casts.  

Science.gov (United States)

The three-dimensional microvascular structure of many organs can be adequately investigated only using the corrosion casting technique. We applied this method, consisting of an injection of low viscosity acrylic resin through the major vessels and the subsequent digestion of the organic component with strong alkali or acids, to the choroid plexus of the lateral ventricles in the rat, focusing on its structural vascular features. This approach allowed a qualitative morphological description of the choroid plexus of the lateral ventricles, revealing several aspects of their capillary architecture as well as the morphological details underlying its main functional activity, essential to cerebrospinal fluid turnover. Observation of the casts with scanning electron microscopy gave a detailed picture of the choroid plexus of the lateral ventricles of the rat and enabled us to distinguish four different regions, depending on the site that the lateral ventricles occupied: the anterior olfactory region, the main central region, the longer branch and the inferior horn. Each region mostly consisted of spiral capillaries and had specific characteristics. At high magnification, the casts revealed distinctive vascular specializations, such as numerous bulges regularly placed on the capillaries. This morphological investigation underpins a better comprehension of the pathological mechanisms involving the choroid plexus in the lateral ventricles. PMID:16229157

Sangiorgi, S; Picano, M; Manelli, A; Peron, S; Tomei, G; Raspanti, M

2003-12-01

5

From vascular corrosion cast to electrical analog model for the study of human liver hemodynamics and perfusion.  

Science.gov (United States)

Hypothermic machine perfusion (HMP) is experiencing a revival in organ preservation due to the limitations of static cold storage and the need for better preservation of expanded criteria donor organs. For livers, perfusion protocols are still poorly defined, and damage of sinusoidal endothelial cells and heterogeneous perfusion are concerns. In this study, an electrical model of the human liver blood circulation is developed to enlighten internal pressure and flow distributions during HMP. Detailed vascular data on two human livers, obtained by combining vascular corrosion casting, micro-CT-imaging and image processing, were used to set up the electrical model. Anatomical data could be measured up to 5--6 vessel generations in each tree and showed exponential trend lines, used to predict data for higher generations. Simulated flow and pressure were in accordance with literature data. The model was able to simulate effects of pressure-driven HMP on liver hemodynamics and reproduced observations such as flow competition between the hepatic artery and portal vein. Our simulations further indicate that, from a pure biomechanical (shear stress) standpoint, HMP with low pressures should not result in organ damage, and that fluid viscosity has no effect on the shear stress experienced by the liver microcirculation in pressure-driven HMP. PMID:20709637

Debbaut, Charlotte; Monbaliu, Diethard; Casteleyn, Christophe; Cornillie, Pieter; Van Loo, Denis; Masschaele, Bert; Pirenne, Jacques; Simoens, Paul; Van Hoorebeke, Luc; Segers, Patrick

2011-01-01

6

A corrosion casting/scanning electron microscope method that simultaneously demonstrates clear outlines of endothelial cells and three-dimensional vascular organization.  

Science.gov (United States)

This paper describes a method that can definitively demonstrate endothelial cell boundaries on corrosion casts of arteries, veins, and capillaries. After perfusion with silver nitrate, a casting medium was injected into the entire vascular bed. The injected tissues were either exposed to light or immersed in the photographic developer to develop the silver halide, and corroded in a 5% NaOH solution at 60 degrees C overnight. Observations of the casts containing water in a low vacuum scanning electron microscope equipped with a cooling stage clearly showed endothelial cell boundaries on casts of every type of vessel as well as their three-dimensional architecture. The low vacuum scanning electron microscope images of wet casts were almost identical in quality to the back-scattered electron images of dried casts without any coating. Secondary electron images of the dried casts with metal coating clearly showed endothelial cell outlines and nuclear imprints. The secondary electron images at high magnification indicated that silver granules were precipitated in the grooves along endothelial cell boundaries on the casts. Since this method can demonstrate endothelial cell boundaries of every type of vessel in addition to their three-dimensional architecture, it will be a powerful tool for examining endothelial cell morphology and microvascular organization in pathological as well as normal tissues. PMID:11201200

Ohtani, O; Ohtani, Y

2000-01-01

7

The venous system of the human foetal spinal cord. Scanning electron microscope of vascular corrosion casts.  

Science.gov (United States)

The investigation was carried out on 16 human foetal cadavers at the age of 17-23 weeks from the time of conception. The foetal vascular system was injected with the synthetic resin MERCOX CL-2R and analysed in scanning electron microscope.The vascular system of the foetal spinal cord was studied. The foetal vascular system was characterised by high variability concerning the number, course and localisation of blood vessels. It contained numerous anastomoses with the internal spinal venous plexuses, which included anterior and posterior radicular veins. Large arteries running on the surface of the spinal cord are accompanied by the homoname veins. The venous system of the investigated foetuses was divided into 2 categories of veins: internal veins responsible for the drainage of blood from the central area, that is central and peripheral veins coming radially to the surface of the spinal cord and external veins, which form the venous system of the surface of the spinal cord. The venous system of the foetal spinal cord was also examined as to the presence of the valves. PMID:24902090

Zawili?ski, J; Zagórska-?wie?y, K; Sk?adzie?, J

2014-05-01

8

Osmium tetroxide labeling of (poly)methyl methacrylate corrosion casts for enhancement of micro-CT microvascular imaging.  

Science.gov (United States)

In order to enhance micro-computer tomography (micro-CT) imaging of corrosion casts of fine vasculature, metals can be added to the casting resin before perfusion. However, perfused metals lead to vasoconstriction or vessel damage resulting in nonphysiologic vascular casts. A novel method for coating methyl methacrylate vascular casts with osmium tetroxide has been developed in order to increase micro-CT contrast without affecting the vascular structure. This technique was verified using corrosion casts of the lung vasculature of New Zealand white rabbits. Osmium tetroxide coating of methyl methacrylate vascular corrosion casts resulted in an increase in overall sample contrast that translated into an increase in the resolution of the vasculature. This method can therefore lead to increased resolution in the characterization of fine vascular structures. PMID:24103507

Mondy, William L; Casteleyn, Christophe; Loo, Denis V; Raja, Muthkrishna; Singleton, Christopher; Jacot, Jeffrey G

2013-12-01

9

Rust and corrosion resistant cast steel  

International Nuclear Information System (INIS)

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)

10

Stress Corrosion Cracking Behavior of Cast Stainless Steels  

International Nuclear Information System (INIS)

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

11

Galvanic corrosion of copper-cast iron couples  

International Nuclear Information System (INIS)

To ensure the safe encapsulation of spent nuclear fuel rods for geological disposal, SKB are considering using the Copper-Cast Iron Canister, which consists of an outer copper canister and an inner cast iron container. The canister will be placed into boreholes in the bedrock of a geologic repository and surrounded by bentonite clay. In the unlikely event of the outer copper canister being breached, water would enter the annulus between the inner and outer canister and at points of contact between the two metals there would be the possibility of galvanic interactions. Although this subject has been considered previously from both a theoretical standpoint and by experimental investigations there was a need for further experimental studies in support of information provided by SKB to the Swedish regulators (SKI). In the work reported here copper-cast iron galvanic couples were set up in a number of different environments representing possible conditions in the SKB repository. The tests investigated two artificial porewaters at 30 deg C and 50 deg C, under aerated and deaerated conditions. Tests were also carried out in a 30 wt% bentonite slurry made up in artificial groundwater. The potential of the couples and the currents passing between the coupled electrodes were monitored for several months. The effect of growing an oxide film on the surface of the cast iron prior to coupling it with copper was investigated. In addition, some crevice specimens based on the multi-crevice assembly (MCA) design were used to simulate the situation where the copper canister will be in direct contact with the cast iron inner vessel. The electrochemical results are presented graphically in the form of electrode potentials and galvanic corrosion currents as a function of time. The galvanic currents in aerated conditions were much higher than in deaerated conditions. For example, at 30 deg C, galvanic corrosion rates as low as 0.02 ?m/year for iron were observed after deaeration, but the corrosion rates were near 100 ?m/year for the cast iron at 50 deg C in the presence of oxygen. There was evidence of temporary polarity reversal at very low levels of current (i.e. the copper became the anode). The galvanic corrosion rates of iron coupled to copper at low groundwater oxygen concentrations were close to the values measured for anaerobic corrosion rates of uncoupled iron. Under deaerated conditions a black film was formed on the surface of the cast iron, which was consistent with the formation of magnetite. The electrochemical potentials of the cast iron-copper couples in deaerated conditions were in the thermodynamically stable regions for magnetite and metallic copper. The galvanic currents under deaerated conditions were higher at 50 deg C than at 30 deg C, by a factor of up to 10. This can be attributed to an increase in the exchange current density for the water reduction reaction on the copper cathode and to an increase in the rate of diffusion processes in the oxide film on cast iron. There was some evidence for an increase in the galvanic corrosion rate in the presence of bentonite slurry compared to fully aqueous artificial groundwaters. Pre-grown corrosion films on cast iron did not have a significant effect on subsequent measured galvanic corrosion rates when coupled to copper in deaerated conditions. None of the MCA specimens exhibited any signs of galvanically enhanced crevice corrosion under deaerated conditions. In terms of application of the results to the evolution of the environment within the annulus of the canister the following scenario is envisaged. If water penetrates the annulus through a hole in the outer copper container a galvanic couple will be set up between the copper and the cast iron insert. The current passing between the copper and the cast iron will be concentrated at the contact points. If any residual air is present in the annulus the corrosion rate of the cast iron will be enhanced (i.e. the iron will be the anode and copper the cathode). In the absence of oxygen in the annulus, as a result of oxygen consu

12

Galvanic corrosion of copper-cast iron couples  

Energy Technology Data Exchange (ETDEWEB)

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 {mu}m/year for iron were observed after deaeration, but the corrosion rates were near 100 {mu}m/year for the cast iron at 50 deg C in the presence of oxygen. There was evidence of temporary polarity reversal at very low levels of current (i.e. the copper became the anode). The galvanic corrosion rates of iron coupled to copper at low groundwater oxygen concentrations were close to the values measured for anaerobic corrosion rates of uncoupled iron. Under deaerated conditions a black film was formed on the surface of the cast iron, which was consistent with the formation of magnetite. The electrochemical potentials of the cast iron-copper couples in deaerated conditions were in the thermodynamically stable regions for magnetite and metallic copper. The galvanic currents under deaerated conditions were higher at 50 deg C than at 30 deg C, by a factor of up to 10. This can be attributed to an increase in the exchange current density for the water reduction reaction on the copper cathode and to an increase in the rate of diffusion processes in the oxide film on cast iron. There was some evidence for an increase in the galvanic corrosion rate in the presence of bentonite slurry compared to fully aqueous artificial groundwaters. Pre-grown corrosion films on cast iron did not have a significant effect on subsequent measured galvanic corrosion rates when coupled to copper in deaerated conditions. None of the MCA specimens exhibited any signs of galvanically enhanced crevice corrosion under deaerated conditions. In terms of application of the results to the evolution of the environment within the annulus of the canister the following scenario is envisaged. If water penetrates the annulus through a hole in the outer copper container a galvanic couple will be set up between the copper and the cast iron insert. The current passing between the copper and the cast iron will be concentrated at the contact points. If any residual air is present in the annulus the corrosion rate of the cast iron will be enhanced (i.e. the iron will be the anode and copper the cathode). In the absence of oxygen in the annulus, as a result of oxygen c

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

2005-01-01

13

Surgical Importance of Arterial Segments of Human Kidneys: An Angiography and Corrosion Cast Study  

Science.gov (United States)

Objective: Variations in the arterial supply of human kidney have been observed frequently, either in routine dissections or surgical practice. The main objective of the present study was to describe the arterial segmental pattern of human kidneys and its variation by angiography and corrosion cast techniques. Materials and Methods: Forty kidneys were washed and a plastic cannula was inserted into renal artery and the omnipaque dye was injected into it and X-ray was taken. The corrosion casts were prepared by injecting coloured acetate butyrate (CAB) granules solution. Results: Five vascular segments of kidney were seen based on the branching pattern of the renal artery by angiography and corrosion cast techniques. The renal artery was divided into anterior and posterior branches. The anterior branch further divided into four branches viz. apical segmental artery (ASA), Upper segmental artery (USA), middle segmental artery (MSA), lower segmental artery (LSA) while the posterior branch continue as posterior segmental artery. The origins of segmental arteries were variable. In 60% cases apical segmental artery (ASA) had common origin with upper segmental artery (USA) while in 40% cases it took origin directly from the main renal artery. Similarly the variations in the origin of the other branches of anterior division of renal artery were observed. The posterior segmental artery (PSA) however was single and comparatively small and supplied the posterior surface of the kidney. Conclusion: The knowledge of the vascular pattern of the kidney is thus important for the purpose of angiography and surgical procedures especially for nephrectomy and kidney transplantation. PMID:24783063

Rani, Neerja; Singh, Seema; Dhar, Pushpa; Kumar, Rani

2014-01-01

14

Corrosion evaluation of traditional and new bronzes for artistic castings  

International Nuclear Information System (INIS)

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

15

Tracers in vascular casting resins enhance backscattering brightness.  

Science.gov (United States)

Studying cast microvasculature with scanning electron microscopy has expanded our knowledge of many circulations, but need arises to determine the blood source of vascular beds that are supplied by two circulations. One way to do this is to mark the casting resin by adding a tracer compound that can be detected in the scanning electron microscope. A potential method of distinguishing different substances is to detect the backscattered electrons that are emitted from the tracer if the tracer is a heavier element, because heavier elements backscatter more electrons. To explore different tracers, we tested lead, titanium, iron, osmium, and uranium as solutions of different polarity and powders. The tracers were added to 1 ml of methyl methacrylate in log concentrations. Shrinkage, hardness, cast quality, and change in brightness from the tracer were compared with multivariate analysis at scanning electron microscopic working distances of 15 and 39 mm on carbon-coated and uncoated specimens. Several concentrations caused sedimentation of the tracer and prevented the resin from solidifying. Tetraethyl lead shortened the hardening time: uranyl acetate and osmium tetroxide prolonged it. Most tracers decreased shrinkage. When lead citrate and Reynolds solutions were removed, the brightness correlated with increasing atomic number, concentration of the tracer, and mean atomic number of the specimen (p elements added to them, but an optimal tracer has not yet been established. PMID:12074492

Schraufnagel, Dean E; Ganesan, Dhanalakshmi P

2002-01-01

16

Microvascularization of the human digit as studied by corrosion casting.  

Science.gov (United States)

The aim of this study was to describe microcirculation in the human digit, focusing on the vascular patterns of its cutaneous and subcutaneous areas. We injected a functional supranumerary human thumb (Wassel type IV) with a low-viscosity acrylic resin through its digital artery. The tissues around the vessels were then digested in hot alkali and the resulting casts treated for scanning electron microscopy. We concentrated on six different areas: the palmar and dorsal side of the skin, the eponychium, the perionychium, the nail bed and the nail root. On the palmar side, many vascular villi were evident: these capillaries followed the arrangement of the fingerprint lines, whereas on the dorsal side they were scattered irregularly inside the dermal papillae. In the hypodermal layer of the palmar area, vascular supports of sweat glands and many arteriovenous anastomoses were visible, along with glomerular-shaped vessels involved in thermic regulation and tactile function. In the eponychium and perionychium, the vascular villi followed the direction of nail growth. In the face of the eponychium in contact with the nail, a wide-mesh net of capillaries was evident. In the nail bed, the vessels were arranged in many longitudinal trabeculae parallel to the major axis of the digit. In the root of the nail, we found many columnar vessels characterized by multiple angiogenic buttons on their surface. PMID:15032919

Sangiorgi, S; Manelli, A; Congiu, T; Bini, A; Pilato, G; Reguzzoni, M; Raspanti, M

2004-02-01

17

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2007-01-01

18

Ranking corrosion efficiency: a Latin square study on rat lung microvascular corrosion casts.  

Science.gov (United States)

Scanning electron microscopy of corrosion casts is an important tool for the study of microvascular structure but few systematic studies on methods of specimen preparation have been reported. This study sought to determine the relative importance of factors involved in corrosion. It compared potassium hydroxide, sodium hydroxide and water as major corrosive agents. It tested the size of the tissue sample, and the use of prealkali autolysis, detergent, and proteolytic enzymes in a Latin square designed study. The main findings were that sodium and potassium hydroxide were better than water (P less than 0.0001) and the longer the corrosion time the better corroded the samples were (P less than 0.0001). Although not a controlled factor, higher room temperature was also associated with better corrosion. The use of proteolytic enzymes, detergent, and warm tap water alone before the alkali treatment did not significantly improve the corrosion in this study, although this does not preclude an effect with another experimental design. PMID:2740868

Schraufnagel, D E

1989-03-01

19

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

International Nuclear Information System (INIS)

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

20

Hierarchical bioimaging and quantification of vasculature in disease models using corrosion casts and microcomputed tomography  

Science.gov (United States)

A wide range of disorders are associated with alterations of the central and peripheral vascular system. Modified vascular corrosion casting using a newly developed polymer, allows for the first time hierarchical assessment of 3D vessel data in animals down to the level of capillaries. Imaging of large volumes of vasculature at intermediate resolution (16 um) was performed using a desktop micro-computed tomography system. Subsequently regions of interest were identified for additional high resolution imaging (1.4 um) at the X-ray Tomographic Microscopy (XTM) station of the Swiss Light Source (SLS). A framework for systematic hierarchical imaging and quantification was developed. Issues addressed included enhanced XTM data acquisition, introduction of local tomography, sample navigation, advanced post processing, and data combination. In addition to visual assessment of qualitative changes, morphometrical and architectural indices were determined using direct 3D morphometry software developed in house. Vessel specific parameters included thickness, surface, connectivity, and vessel length. Reconstructions of cerebral vasculature in mutant mice modeling Alzheimer's disease revealed significant changes in vessel architecture and morphology. In the future, a combination of these techniques may support drug discovery. Additionally, future ultra-high-resolution in vivo systems may even allow non-invasive tracking of temporal alterations in vascular morphology.

Heinzer, Stefan; Krucker, Thomas; Stampanoni, Marco; Abela, Rafael; Meyer, Eric P.; Schuler, Alexandra; Schneider, Philipp; Muller, Ralph

2004-10-01

 
 
 
 
21

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

International Nuclear Information System (INIS)

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.)

22

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

International Nuclear Information System (INIS)

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

23

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

International Nuclear Information System (INIS)

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.)

24

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

Directory of Open Access Journals (Sweden)

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

B. Kalandyk

2013-01-01

25

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Gawron?ski, J.

2010-01-01

26

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

International Nuclear Information System (INIS)

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

27

Effect of chemical composition on the corrosion behavior of Ni-Cr-Mo dental casting alloys.  

Science.gov (United States)

The objective of this investigation was to study the compositional influence on the corrosion behavior of Ni-Cr-Mo dental casting alloys in acidic artificial saliva. Cyclic potentiodynamic and potentiostatic tests were used to evaluate the corrosion behavior of different Ni-Cr-Mo dental casting alloys in deaerated artificial saliva with pH 5 at 37 degrees C. Optical microscope observations were made following the cyclic potentiodynamic tests. Surface chemical analyses were characterized by X-ray photoelectron spectroscopy and auger electron spectroscopy following the potentiostatic tests. The results show that the corrosion resistance of the Ni-Cr-Mo casting alloys investigated is associated with the formation of passive film containing Ni(OH)(2), NiO, Cr(2)O(3), and MoO(3), on the surface. The pitting potential and passive range, respectively, were statistically different among the different Ni-Cr-Mo alloys. The Ni-Cr-Mo alloys with higher Cr ( approximately 21%) and Mo ( approximately 8%) contents had a much larger passive range in the polarization curve and were immune to pitting corrosion due to the presence of high Cr (maximum approximately 31-35%) and Mo (maximum approximately 12%) contents in the surface passive film. The presence of Ti lower than 4% in the Ni-Cr-Mo casting alloy had no effect on corrosion resistance. A pitting resistance equivalent (PRE) of about 49 could provide the Ni-Cr-Mo alloy with a good pitting corrosion resistance. PMID:11920670

Huang, Her-Hsiung

2002-06-01

28

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

Directory of Open Access Journals (Sweden)

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

B. Bobic

2011-06-01

29

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

Directory of Open Access Journals (Sweden)

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

M. Starowicz

2009-10-01

30

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

International Nuclear Information System (INIS)

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

31

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

International Nuclear Information System (INIS)

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

32

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

International Nuclear Information System (INIS)

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

33

Influence of casting procedures on the corrosion resistance of clinical dental alloys containing palladium.  

Science.gov (United States)

The aim of this study was to compare the in vitro corrosion resistance in artificial saliva of two palladium-silver alloys (a Pd-Ag (Pors on 4) and an Ag-Pd (Palliag LTG)), with and without casting defects; 1 nickel-chrome alloy and 1 high-gold alloy, cast under recommended conditions, served as controls. For each of the palladium-based alloys, three specimens corresponding to three different casting conditions were used: under recommended conditions, with the use of a graphite-containing investment and crucible, and by reusing the sprues and sprue button. The electrochemical tests were run in Fusayama-Meyer artificial saliva. The open-circuit potential was recorded in mV/SCE at t=24h. Then, potentiodynamic polarization was performed to measure the polarization resistance (R(p)) in kOmega cm(2) and the corrosion current (i(corr)) in microA cm(-2). Data were evaluated with one-way analysis of variance and multiple comparisons test (alpha=0.05). In addition, each specimen was examined by scanning electron microscopy. Compared to the control alloys, the electrochemical experiments in artificial saliva indicated satisfactory corrosion resistance for the Pd-Ag and Ag-Pd alloys; these results are related to their high noble metal content and stable substructure. The Pd-Ag alloy displayed superior electrochemical properties to those of the Ag-Pd alloy regardless of the casting condition. The use of the graphite-containing crucible and investment during the cast process did not dramatically reduce the corrosion resistance values, but the reuse of sprues and the sprue button did. The optimal corrosion resistance values were obtained for the alloys cast according to the recommended conditions. PMID:16701891

Viennot, Stéphane; Lissac, Michèle; Malquarti, Guillaume; Dalard, Francis; Grosgogeat, Brigitte

2006-05-01

34

Corrosion of Cast Iron Mill Plates in Wet Grinding  

Directory of Open Access Journals (Sweden)

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.

Anthony ANDREWS

2010-12-01

35

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

Energy Technology Data Exchange (ETDEWEB)

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 {beta} transus. All of the samples exhibited active-passive transitions in deaerated 5% HCl at room temperature, but the {beta} 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 {alpha} and {beta} phases.

Atapour, M. [Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210 (United States); Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Pilchak, A. [Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210 (United States); Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base, OH 45433 (United States); Universal Technology Corporation, Dayton, OH 45432 (United States); Frankel, G.S., E-mail: frankel@matsceng.ohio-state.ed [Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210 (United States); Williams, J.C. [Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210 (United States)

2010-09-15

36

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-07-01

37

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

International Nuclear Information System (INIS)

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)

38

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

Directory of Open Access Journals (Sweden)

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

J. Gawro?ski

2010-01-01

39

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

International Nuclear Information System (INIS)

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

40

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

Energy Technology Data Exchange (ETDEWEB)

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.

Mousavi Anijdan, S.H. [Mining, Metals and Materials Engineering Department, McGill University, M.H. Wong Building, 3610 University Street, Montreal, H3A 2B2 (Canada); Materials Science and Engineering Department, Sharif University of Technology, P.O. Box 11365-9944, Tehran (Iran, Islamic Republic of)], E-mail: hashem.mousavi@mail.mcgill.ca; Bahrami, A. [Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft (Netherlands); Varahram, N. [Materials Science and Engineering Department, Sharif University of Technology, P.O. Box 11365-9944, Tehran (Iran, Islamic Republic of); Davami, P. [Materials Science and Engineering Department, Sharif University of Technology, P.O. Box 11365-9944, Tehran (Iran, Islamic Republic of)

2007-04-25

 
 
 
 
41

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

Science.gov (United States)

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

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

2012-09-01

42

Rapid casting of patterned vascular networks for perfusable engineered 3D tissues  

Science.gov (United States)

In the absence of perfusable vascular networks, three-dimensional (3D) engineered tissues densely populated with cells quickly develop a necrotic core [1]. Yet the lack of a general approach to rapidly construct such networks remains a major challenge for 3D tissue culture [2–4]. Here, we 3D printed rigid filament networks of carbohydrate glass, and used them as a cytocompatible sacrificial template in engineered tissues containing living cells to generate cylindrical networks which could be lined with endothelial cells and perfused with blood under high-pressure pulsatile flow. Because this simple vascular casting approach allows independent control of network geometry, endothelialization, and extravascular tissue, it is compatible with a wide variety of cell types, synthetic and natural extracellular matrices (ECMs), and crosslinking strategies. We also demonstrated that the perfused vascular channels sustained the metabolic function of primary rat hepatocytes in engineered tissue constructs that otherwise exhibited suppressed function in their core. PMID:22751181

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

2012-01-01

43

Three-dimensional relationships between tumor cells and microcirculation with double cyanine immunolabeling, laser scanning confocal microscopy, and computer-assisted reconstruction: an alternative to cast corrosion preparations.  

Science.gov (United States)

The morphology of the microcirculation of uveal melanomas is a reliable market of tumor progression. Scanning electron microscopy of cast corrosion preparations can generate three-dimensional views of these vascular patterns, but this technique sacrifices the tumor parenchyma. Formalin-fixed wet tissue sections 100-150 microns thick from uveal melanomas were stained with the lectin Ulex europaeus agglutinin I (UEAI) and proliferating cell nuclear antigen (PCNA) to demonstrate simultaneously the tumor blood vessels and proliferating tumor cells. Indocarbocyanine (Cy3) was used as a fluorophore for UEAI and indodicarbocyanine (Cy5) was used for PCNA. Double labeled sections were examined with a laser scanning confocal microscope. Images of both stains were digitized at the same 5-microns intervals and each of the two images per interval was combined digitally to form one image. These combined images were visualized through voxel processing to study the relationship between melanoma cells expressing PCNA and various microcirculatory patterns. This technique produces images comparable to scanning electron microscopy of cast corrosion preparations while permitting simultaneous localization of melanoma cells expressing PCNA. The microcirculatory tree can be viewed from any perspective and the relationship between tumor cells and the tumor blood vessels can be studied concurrently in three dimensions. This technique is an alternative to cast corrosion preparations. PMID:7908912

Rummelt, V; Gardner, L M; Folberg, R; Beck, S; Knosp, B; Moninger, T O; Moore, K C

1994-05-01

44

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

International Nuclear Information System (INIS)

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)

45

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

Energy Technology Data Exchange (ETDEWEB)

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.)

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

2001-07-01

46

Corrosion resistance of the die casting AZ91D magnesium alloys with paint finishing  

Energy Technology Data Exchange (ETDEWEB)

It was found that magnesium and its alloys have high potentialities for the application in automobiles, computer equipment, portable tools and so on. The main problem in the usage of magnesium and its alloys had been their corrosive characteristics, but owing to the recent progress in manufacturing impurity-free technology, the corrosion damage is being drastically reduced. This paper reports the results of salt spray tests and exposure tests on AZ91D magnesium and ADC12 aluminum alloys die cast panels with paint finishing. (orig.)

Umehara, Hiroyki [National Inst. of Materials and Chemical Research, Tsukuba, Ibaraki (Japan); Takaya, Matsufumi [Ciba Inst. of Technology, Tsukuba (Japan); Itoh, Tetsuzi [Japan Weathering Test Centre, Tsukuba (Japan). Choshi Exposure Lab.

1999-07-01

47

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

Science.gov (United States)

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

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

2014-08-01

48

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

Science.gov (United States)

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

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

2013-06-01

49

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

International Nuclear Information System (INIS)

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

50

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

Directory of Open Access Journals (Sweden)

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

F. A. Ovat

2012-08-01

51

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2003-12-01

52

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

Directory of Open Access Journals (Sweden)

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

Berardinelli Paolo

2009-07-01

53

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

Science.gov (United States)

Background The present research aims to describe the process of vascular readjustment occurring in pig ovary during the periovulatory phase (from LH surge to ovulation) that drives the transformation of the follicle, a limited blood supplied structure, into the corpus luteum, a highly vascularised endocrine gland required to maintain high levels of progesterone in pregnancy. The swine model was chosen because it is characterized by a long periovulatory window (about 40–44 hrs-similar to human) that permits to recover follicles at a precise endocrinological timing. Methods By validated hormonal protocol (eCG+hCG), able to mimic the physiologic gonadotropin stimulation, preovulatory follicles (PreOFs, 60 h-eCG), follicles in the middle (early periovulatory follicles, EPerOFs, 18 h-hCG) or late (LPerOFs, 36 h-hCG) periovulatory phase were isolated from prepubertal gilts. To understand the angiogenic process, morphological/morphometrical analyses were performed by combining immunohistochemistry (IHC) and SEM of vascular corrosion casts (VCC) techniques. Results PreOFs showed a vascular plexus with proliferating endothelial cells (EPI). This plexus was characterized by a dense inner capillary network, with angiogenic figures, connected to the outer network by anastomotic vessels (arterioles and venules of the middle network). EPerOFs decreased their EPI, blood vessel extension in the outer network, and evidenced a reduced compactness of blood vessels. In LPerOFs, a rapid neovascularization was associated to an intensive tissue remodeling: the follicle acquired an undulated aspect presenting arterioles/venules near the basal membrane, increased vascular extension by EPI, sprouting and non-sprouting angiogenesis. The analysis of vascular geometric relations and branching angles evidenced similar values at all stages. Conclusion These data allow us to hypothesize that EPerOFs are in a quiescent status. LPerOFs represent the "metamorphic" follicles that rapidly turn-on angiogenesis to sustain a successful corpus luteum formation. Particularly, it is interesting to underlie that the non-sprouting angiogenesis, typical of structures in rapid neovascularization, occurred only in the LPerOFs. Moreover, vascular geometric relations showed as blood vessel remodeling occurs with the "maximum output and the minimum energetic expense". This knowledge will allow to better understand the mechanisms regulating the reproductive success and to clarify the complex physiological angiogenic process in adult tissues. PMID:19607713

Martelli, Alessandra; Palmerini, Maria Grazia; Russo, Valentina; Rinaldi, Carlo; Bernabo, Nicola; Di Giacinto, Oriana; Berardinelli, Paolo; Nottola, Stefania Annarita; Macchiarelli, Guido; Barboni, Barbara

2009-01-01

54

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

International Nuclear Information System (INIS)

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)

55

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

Science.gov (United States)

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

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

2014-11-15

56

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

International Nuclear Information System (INIS)

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

57

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

International Nuclear Information System (INIS)

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

58

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

International Nuclear Information System (INIS)

Magnesium alloys are often used in as-cast conditions. So, the aim of this work is to characterize the corrosion protection of as-cast AZ91D alloys coated with simple chemical conversion (phosphate-permanganate, and cerium-based coatings). With the two coatings, the electrochemical measurements show that the corrosion protection is due to both the inhibition of cathodic and anodic reactions, because of the presence of stable CeO2 or manganese oxides in basic pH. Nevertheless, the non-electrochemical tests of corrosion are required to bring to light the healing effect of phosphate-permanganate coating compared to Ce-coating and to describe the corrosion behaviour completely. Finally phosphoric and soda pickling associated to phosphate-permanganate conversion treatment or cerium coating are ecologically efficient alternatives to fluoride-based pickling and the chromating treatment.

59

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

International Nuclear Information System (INIS)

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

60

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

Energy Technology Data Exchange (ETDEWEB)

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% H{sub 2}SO{sub 4} aqueous solution for general corrosion resistance and the slow strain rate tests were also conducted in air and 3.5% NaCl+5% H{sub 2}SO{sub 4} 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.

Jang, Young Hwan; Son, Jin Il; Kim, Sang Shik [Gyeongsang National University, Chinju (Korea, Republic of); Lee, Je Hyun [Changwon National University, Changwon (Korea, Republic of)

2005-03-15

 
 
 
 
61

Effect of testing frequency on the corrosion fatigue of a squeeze-cast aluminum alloy  

Energy Technology Data Exchange (ETDEWEB)

The corrosion fatigue crack propagation behavior of a squeeze-cast Al-Si-Mg-Cu aluminum alloy (AC8A-T6), which had been precracked in air, was investigated at testing frequencies of 0.1, 1, 5, and 10 Hz under a stress ration (R) of 0.1. Compact-toughness specimens were precracked about t mm in air prior to the corrosion fatigue test in a 3 pct saline solution. At some near-threshold conditions, these cracks propagated faster than would be predicted by the mechanical driving force. This anomalous corrosion fatigue crack growth was affected by the initial stress-intensity-factor range ({Delta}K{sub i}), the precracking conditions, and the testing frequency. The initial crack propagation rate was as much as one order of magnitude higher than the rate for the same conditions in air. This rapid rate was associated with preferential propagation along the interphase interface in the eutectic structure. It is believed that a chemical reaction at the crack tip and/or hydrogen-assisted cracking produced the phenomenon. Eventual retardation and complete arrest of crack growth after this initial rapid growth occurred within a short period at low {Delta}K values, when the testing frequency was low (0.1 and 1 Hz). This retardation was accompanied by corrosion product-induced crack closure and could be better explained by the contributory stress-intensity-factor range ({Delta}K{sub cont}) than by the effective stress-intensity-factor range ({Delta}k{sub eff}).

Shiozawa, Kazuaki; Sun, Shuming; Eadie, R.L.

2000-04-01

62

Nitride precipitation during high temperature corrosion of ductile cast irons in synthetic exhaust gases  

Science.gov (United States)

Internal nitrides form in two ductile cast irons (SiMo and Ni-Resist) intended for exhaust systems in vehicles. Samples oxidised at 650 1050 °C for 50 h in modified synthetic exhaust gases were analysed by using AES and FEG-SEM. No nitrides formed in absence of NOx. In dry petrol gas coarse nitrides (diffusion paths and increased N solubility as Si was depleted contribute to a self-accelerating process. The Si depletion around the coarse nitrides lowered the microhardness and the corrosion resistance of the alloy. In diesel and in normal petrol gases ?-sized MgSiN2 form in SiMo in cell boundaries where Mg segregates. This also occurs in Ni-Resist in both dry and normal petrol whereas no nitrides were observed in Ni-Resist exposed to diesel gases.

Tholence, F.; Norell, M.

2005-02-01

63

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

International Nuclear Information System (INIS)

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

64

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

International Nuclear Information System (INIS)

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

65

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

Science.gov (United States)

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

Krajewski, Katherine Mary

66

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

1981-07-01

67

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

International Nuclear Information System (INIS)

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

68

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

International Nuclear Information System (INIS)

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

69

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

Science.gov (United States)

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

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

2014-09-01

70

Quantitative measure of small vessel anastomotic contour using corrosion resin cast models: an aid to surgical training.  

Science.gov (United States)

A surgeon who had not previously carried out a small vessel anastomosis performed 20 consecutive anastomoses between human long saphenous vein and the left anterior descending artery of a pig's heart. Corrosion resin cast models were made of the anastomoses and subjected to a quantitative analysis of the anastomotic contour. A trend of improvement in contour parameters was found with increasing experience. This model may be useful for surgeons in training. PMID:1760709

John, L C; Hornick, P; Rees, G M; Edmondson, S J

1991-11-01

71

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

International Nuclear Information System (INIS)

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 ?, ?, 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)

72

Maximizing Modern Distribution of Complex Anatomical Spatial Information: 3D Reconstruction and Rapid Prototype Production of Anatomical Corrosion Casts of Human Specimens  

Science.gov (United States)

Anatomical corrosion casts of human specimens are useful teaching aids. However, their use is limited due to ethical dilemmas associated with their production, their lack of perfect reproducibility, and their consumption of original specimens in the process of casting. In this study, new approaches with modern distribution of complex anatomical…

Li, Jianyi; Nie, Lanying; Li, Zeyu; Lin, Lijun; Tang, Lei; Ouyang, Jun

2012-01-01

73

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

International Nuclear Information System (INIS)

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

74

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

Science.gov (United States)

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

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

2003-08-01

75

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2009-01-01

76

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

Science.gov (United States)

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.

Miner, R. V., Jr.

1977-01-01

77

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-06-30

78

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-01-01

79

Slurry erosion-corrosion characteristics of squeeze cast aluminum alloy-aluminum borate composite  

Energy Technology Data Exchange (ETDEWEB)

The slurry erosion-corrosion behavior of 19.5 vol.% Al{sub 18}B{sub 4}O{sub 33} whisker reinforced AC4C Al composite in aqueous slurry containing 3.5 wt.% NaCl and 20 wt.% silica has been investigated using a jet-in-slit rig. Erosion-corrosion tests were performed with slurry having a jet velocity range 6.4 ms{sup -1} to 15.2 ms{sup -1} and at normal impact angle. The results indicated that the slurry erosion-corrosion characteristics were affected by the slurry velocity and material properties. At low slurry velocities, as compared to the unreinforced alloy, the erosion-corrosion resistance of the composite was improved because of increase in hardness as a result of whisker addition. However, steady-state erosion-corrosion rate was found to increase with the addition of whisker to the matrix alloy at high slurry velocities. The erosion-corrosion rates of materials in the saline slurry were much higher than those in the water slurry even though the corrosion components were very small. It is found that the synergistic factor for the materials reduced with increasing slurry velocity although the synergism between erosion and corrosion was greater at high slurry velocity. Localized corrosion occuring in the strain-hardened layer caused a decrease in the fracture strain of composite during erosion-corrosion. In the saline slurry, the material removal was enhanced through cracking of flakes and detaching of whisker induced by stress and corrosion. (orig.) 26 refs.

Tu, J.P. [Zhejiang Univ., ZJ (China). Dept. of Materials Science and Engineering; Li, C.L.; Zhao, H.X.; Matsumura, M. [Hiroshima Univ. (Japan). Dept. of Chem. Eng.

1999-04-01

80

Microvascular architecture of mouse urinary bladder described with vascular corrosion casting, light microscopy, SEM, and TEM.  

Science.gov (United States)

The urinary bladder is a unique organ in that its normal function is storage and release of urine, and vasculature in its wall exhibits specialized features designed to accommodate changes in pressure with emptying and filling. Although we have previously described the fine details of the microvasculature of the urinary bladder of the rabbit and dog, information on the fine details of the microvasculature of the mouse bladder were deemed to be of value because of the increasing use of this species in developing genetic models for studying human disorders. The present study shows that many of the special features of the microvasculature of the mouse urinary bladder are similar to those described in the rabbit and dog, including vessel coiling, abundant collateral circulation, arterial sphincters, and a dense mucosal capillary plexus. PMID:24029590

Hossler, Fred E; Lametschwandtner, Alois; Kao, Race; Finsterbusch, Friederike

2013-12-01

 
 
 
 
81

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

International Nuclear Information System (INIS)

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

82

Corrosion fatigue crack growth behavior of a squeeze-cast Al-Si-Mg-Cu alloy with different precrack histories  

Energy Technology Data Exchange (ETDEWEB)

Fatigue experiments have been performed on a squeeze-cast Al-Si-Mg-Cu alloy as a function of precrack history. The precracked conditions were that the compact tension specimen was precracked with a relatively long-through-thickness crack (about 6 mm) in air, in aqueous 3 pct NaCl solution, and in air followed by hydrogen precharging. It was found that a relatively long through-thickness crack can grow more rapidly than would be predicted by a traditional {Delta}K involving three stages under either a corrosion fatigue test after precracking in air or a hydrogen precharging experiment followed by fatigue testing in air. The experimental evidence confirms that a hydrogen-assisted damage mechanism is mainly responsible for the rapid growth phenomenon of a relatively long crack in a corrosive environment compared to the result of fatigue testing in air after hydrogen precharging. The amount of hydrogen production in chemical-microstructure interaction processes in a corrosion fatigue experiment and the effectiveness of hydrogen transport to the region ahead of the crack tip determine the degree of hydrogen-assisted fatigue crack growth, which is controlled by the microstructure of the alloy and the chemical attack on a sharp and fresh crack tip.

Shiozawa, Kazuaki; Sun, Shuming [Toyama Univ. (Japan). Dept. of Mechanical Systems Engineering

1997-07-01

83

Rapid casting of patterned vascular networks for perfusable engineered 3D tissues  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the absence of perfusable vascular networks, three-dimensional (3D) engineered tissues densely populated with cells quickly develop a necrotic core [1]. Yet the lack of a general approach to rapidly construct such networks remains a major challenge for 3D tissue culture [2–4]. Here, we 3D printed rigid filament networks of carbohydrate glass, and used them as a cytocompatible sacrificial template in engineered tissues containing living cells to generate cylindrical networks which could b...

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

2012-01-01

84

Blood vessels in Trichinella spiralis infections: a study using vascular casts.  

Science.gov (United States)

Larvae of Trichinella spiralis initiate the transformation of myocytes into nurse cells that become surrounded by elaborate networks of blood vessels. To examine the structure of these networks (i.e., retes), transcardic perfusion was used to clear the vascular tree of Trichinella-infected mice and to inject a plastic that polymerized in situ. Vascular complexes were found only around infected myocytes and were characterized by large circumferential vessels that give rise to the smaller channels of the retes. The secondary vessels vary widely in caliber and are distributed in a random fashion. Three types of network were found: simple, complex, and hypercomplex, and they were distributed normally, with the complex retes the most common. Comparison of the structure of the baskets with that of vessels in surrounding uninfected muscle strongly suggests that the vascular retes are the result of de novo angiogenesis induced during the infection. The parasite may elicit angiogenesis directly through secretion of unique products or may elicit a change in the nurse cell that, in turn, results in growth of new blood vessels. PMID:1992100

Baruch, A M; Despommier, D D

1991-02-01

85

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

International Nuclear Information System (INIS)

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

86

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

International Nuclear Information System (INIS)

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

87

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

International Nuclear Information System (INIS)

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

88

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

Science.gov (United States)

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.

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

2009-08-01

89

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

International Nuclear Information System (INIS)

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

90

SCC growth behavior of cast stainless steels in high-temperature water. Influences of corrosion potential, steel type, thermal aging and cold-work  

International Nuclear Information System (INIS)

Recent studies on crack growth rate (CGR) measurement in oxygenated high-temperature pure water conditions, such as normal water chemistry (NWC) in BWRs, using compact tension (CT) type specimens have shown that stainless steel weld metal are susceptible to stress corrosion cracking (SCC). On the other hand, the authors reported that no significant SCC growth was observed on stainless steel weld metals in PWR primary water at temperatures from 250degC to 340degC. Cast austenitic stainless steels are widely used in light water reactors, and there is a similarity between welded and cast stainless steels in terms of the microstructure of the ferrite/austenite duplex structure. However, there are a few reports giving CGR data on cast stainless steels in the BWRs and PWRs. The principal purpose of this study was to examine the SCC growth behavior of cast stainless steels in simulated PWR primary water. A second objective was to examine the effects on SCC growth in hydrogenated and oxygenated water environments at 320degC of: (1) corrosion potential; (2) steels type (Mo in alloy); (3) thermal-aging (up to 400degC x 40 kh); and (4) cold-working (10%). The results were as follows: (1) No significant SCC growth was observed on all types of cast stainless steels: aged (400degC x 40 kh) of SCS14A and SCS13A and 10% cold-working, in hydrogenated (low-potential) water at 320degC. (2) Aging at 400degC x 40 kh SCS14A (10%CW) markedly accelerated the SCC growth of cast material in high-potential water at 320degC, but no significant SCC growth was observed in the hydrogenated water, even after long-term thermal aging (400degC x 40 kh). (3) Thus, cast stainless steels have excellent SCC resistance in PWR primary water. (4) On the other hand, significant SCC growth was observed on all types of cast stainless steels: 10%CW SCS14A and SCS13A, in 8 ppm-oxygenated (high-potential) water at 320degC. (5) No large difference in SCC growth was observed between SCS14A (Mo) and SCS13A. (6) No large effect on SCC growth was observed in specimens before and after aging up to 400degC for 10 kh. (7) Long-term aging at 400degC for 40 kh markedly accelerated the SCC growth of cast stainless steel. According to these results, a clear corrosion potential dependence on SCC growth behavior of cast stainless steels was recognized. (author)

91

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

International Nuclear Information System (INIS)

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

92

Radiographic aspects and angioarchitectural arrangements in corrosion casts of the blood supply to the human sternocleidomastoid muscle by the sternocleidomastoid branch of the occipital artery  

Directory of Open Access Journals (Sweden)

Full Text Available The contribution of the sternocleidomastoid branch of the occipital artery (superior arterial pedicle - SAP to the irrigation of the sternocleidomastoid muscle (SCM was evaluated in fresh human cadavers by injecting radiological dye and a resin for microvasculature corrosion casts. From its insertion in the mastoid process of the temporal bone, the SCM was divided into superior, medium, and inferior thirds. In most of the SCM, The SAP are formed by two longitudinal parallel branches. In all specimens, the radiological dye injected into the SAP reached or trespassed the middle part of the studied SCM. The SAP was poorly distributed in the lowermost region of the inferior third of the SCM, suggesting the contribution of other arteries or pedicles. The corrosion casts of the microvasculature showed a profuse network of microscopic vessels in those levels where the SAP was detected.

Fróes Luis Bernardo

1999-01-01

93

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

Science.gov (United States)

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.

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

2014-09-01

94

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

Science.gov (United States)

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

Jain, Syadwad

95

JTE-522, a selective COX-2 inhibitor, interferes with the growth of lung metastases from colorectal cancer in rats due to inhibition of neovascularization: a vascular cast model study.  

Science.gov (United States)

The lung is a frequent site of metastasis from colorectal cancer, but angiogenesis of lung metastases has not been clarified. Some COX-2 inhibitors prevent tumor growth, although the inhibitory mechanism at the metastatic site is obscure. We investigated the microvascular structure of small lung metastases and the effect of JTE-522, a selective COX-2 inhibitor, on the angiogenesis of pulmonary metastases from colorectal cancer in rats. The tail veins of 25 male F344/DuCrj rats, aged 5 weeks, were injected with a tumor suspension containing 5 x 10(6) RCN-9, a rat colon cancer cell line. Three weeks later, pulmonary vascular resin corrosion casts were taken and the vascularity of metastases was studied using stereo and scanning electron microscopes. We investigated the effect of 0, 10 and 30 mg/kg/day of JTE-522 on the angiogenesis of pulmonary metastases in 3 groups of 5 male rats out of 25. JTE-522 reduced the diameter of tumor vessels as well as the number and size of metastatic tumors. The diameter of tumor vessels and the size of lung metastases significantly and positively correlated with neovascularization in the control group, but not in the JTE-522-treated groups. JTE-522 also affected type of vasculature of metastases, which differed depending on their size. JTE-522 interfered with the growth of hematogenous metastatic tumors by disrupting neovascularization. However, JTE-522 may have some important mechanisms other than inhibition of neovascularization. JTE-522 may be one of the therapeutic agents for the treatment of hematogenous metastasis of colorectal cancer. PMID:15386343

Kobayashi, Hirotoshi; Gonda, Tsuyoshi; Uetake, Hiroyuki; Higuchi, Tetsuro; Enomoto, Masayuki; Sugihara, Kenichi

2004-12-20

96

Corrosion  

International Nuclear Information System (INIS)

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

97

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  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. ...

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

2013-01-01

98

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

International Nuclear Information System (INIS)

ed by the action of various concentration cells. Waterline effects due to aeration cells or other concentration cells have been shown to increase the risk for corrosion damage locally, even when the overall corrosion rate does not increase, since corrosion is concentrated to a smaller area and may have a more localised character. Waterline conditions can also develop at a cast-in metal surface inside partly water-filled voids in the concrete. Voids as such at a concrete/metal interface, leaving metal without adhering concrete, have also been shown to increase the corrosion risk. In laboratory experiments, corrosion on bare (not concrete-covered) metal surfaces occurred at quite low chloride concentration and high pH value in the surrounding concrete. Based on the results of the investigations of the corrosion status of the steel liner, and of the concrete samples from the reactor containment the following conclusions can be stated: Visual inspections of the corrosion state of the steel liner showed that there was only superficial corrosion on the liner. The liner had not been subject to waterline corrosion. The appearance of the corrosion products on the steel liner varied with the supply of oxygen. Red, grey and black-coloured corrosion products were present, presumably iron oxide-hydroxide (FeOOH), hematite (Fe2O3), and magnetite (Fe3O4). The superficial corrosion that was observed on the steel liner is probably due to the fact that the reactor containment has been drained of water since 2000, which locally changed the environment in the interface between concrete and steel: drying-up, with better access of air (oxygen). The overall state of the concrete in the examined core samples is good. The crack frequency in the concrete is low, except in the outmost (0-2 mm) concrete layer. The top layer with a high frequency of microcracks in the concrete samples has a maximum depth of 2 mm in all samples except 1:5 (high frequency of cracks to a depth of 11 mm) and 3:3 (high frequency of cracks to a depth of 14 mm). The pH value of the water in contact with the concrete binder is 12,5. The outer layer of the concrete (0-2 mm depth in concrete) is carbonated and shows signs of water damage. Secondary ettringite had formed in the voids of the concrete as a result of the exposure to humidity. This has no significant influence on the properties of the concrete

99

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

Science.gov (United States)

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

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

2014-08-01

100

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

Directory of Open Access Journals (Sweden)

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.

A. Öz

2013-07-01

 
 
 
 
101

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

International Nuclear Information System (INIS)

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

102

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

Energy Technology Data Exchange (ETDEWEB)

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}.

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

103

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

Science.gov (United States)

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

104

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

Directory of Open Access Journals (Sweden)

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

Tatjana Puskar

2014-09-01

105

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 tortuous afferent vessels and frequently emitted multiple efferent arterioles. The glomeruli in the juxtamedullary layer of the kidneys of the aged person were rather small in size and contained degenerative capillary networks. This observation suggests that the medulla of the kidneys of the aged is poorly supplied with blood.

Hitomi,Kusukuma

1987-08-01

106

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

International Nuclear Information System (INIS)

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

107

Tissue engineering: Perfusable vascular networks  

Science.gov (United States)

A rapid vascular casting approach that uses carbohydrate glass as a sacrificial template allows tissues to be built that can be kept alive for longer in the laboratory until needed for transplantation.

Forgacs, Gabor

2012-09-01

108

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

International Nuclear Information System (INIS)

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

109

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

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer Mo influence on corrosion of DSS was studied with industrial and laboratory heats. Black-Right-Pointing-Pointer Beneficial effect of Mo was associated with ferrite corrosion resistance. Black-Right-Pointing-Pointer Mo-species in the alkaline solution did not improve pit resistance. Black-Right-Pointing-Pointer 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.

Mesquita, T.J. [LEPMI, UMR5279CNRS, Grenoble INP, Universite de Savoie, Universite Joseph Fourier, BP 75, 38402 St Martin d' Heres (France); CRU Ugitech, Av Paul Girod 73400 Ugine (France); Chauveau, E.; Mantel, M. [CRU Ugitech, Av Paul Girod 73400 Ugine (France); Kinsman, N. [International Molybdenum Association, IMOA W4 4JE London (United Kingdom); Roche, V. [LEPMI, UMR5279CNRS, Grenoble INP, Universite de Savoie, Universite Joseph Fourier, BP 75, 38402 St Martin d' Heres (France); Nogueira, R.P., E-mail: ricardo.nogueira@grenoble-inp.fr [LEPMI, UMR5279CNRS, Grenoble INP, Universite de Savoie, Universite Joseph Fourier, BP 75, 38402 St Martin d' Heres (France)

2012-02-15

110

Bimetallic layered castings alloy steel – grey cast iron  

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

T. Wróbel

2011-04-01

111

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

Scientific Electronic Library Online (English)

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

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

2014-06-01

112

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

Scientific Electronic Library Online (English)

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

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

2008-06-01

113

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

Scientific Electronic Library Online (English)

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

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

114

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

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

Peng Hao

2011-02-01

115

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

Science.gov (United States)

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

Deadmore, D. L.

1984-01-01

116

Malformações vasculares / Vascular malformations  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Com o conhecimento cada vez maior da angiogênese, as anomalias vasculares foram divididas em tumores e malformações vasculares. As malformações vasculares, objeto deste trabalho, são categorizadas ou pela natureza dos canais vasculares (capilares, arteriais, venosos ou linfáticos), ou pelo tipo de f [...] luxo (alto ou baixo), ou ainda pela distribuição (localizadas ou difusas). Além disso, há as malformações complexas combinadas, nas quais se encaixa a maioria das síndromes vasculares. Os autores apresentam uma revisão do asssunto, discorrendo sobre características clínicas, diagnóstico e tratamento dessas anomalias. Abstract in english As a result of increased knowledge on angiogenesis, vascular anomalies have been separated into tumors and vascular malformations. Vascular malformations, the subject of this review, are classified either by the nature of the vessels (capillary, arterial, venous or lymphatic), type of flow (high or [...] low) or even by distribution (localized or diffuse). Furthermore there are the complex-combined malformations, a feature present in most vascular syndromes. A review of the clinical aspects, diagnosis and treatment of vascular malformations is presented in this paper.

Bernardo, Gontijo; Luciana Baptista, Pereira; Cláudia Márcia Resende, Silva.

117

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

Science.gov (United States)

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

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

2014-08-01

118

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

Science.gov (United States)

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

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

1987-01-01

119

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

Science.gov (United States)

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

Ruhl, Aki S; Jekel, Martin

2013-10-15

120

Enrichment of Casting Surface in Founding Process  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2007-01-01

 
 
 
 
121

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

International Nuclear Information System (INIS)

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

122

Casting Manipulation  

Science.gov (United States)

We have been developing a casting manipulator which includes a flexible string in the link mechanism in order to enlarge workspace of the manipulator. We proposed the swing motion control as the first step of casting manipulation. In this paper we deal with swing motion and throwing motion of casting manipulation. First, we show a method of generating pendulum swing and demonstrate the effectiveness of the proposed control method through experiments using a prototype casting manipulator. Next, we clarify that the main factors which disturb throwing motion are the time delay of releasing a gripper and frictional force which also disturbs flying motion of the gripper based on the results of throwing experiments. We propose a method of compensating these factors. Through the evaluation by comparing the results of numerical simulation with those of experiments, we show that the proposed method helps to reduce the position error of the gripper which reaches to the target.

Arisumi, Hitoshi; Yokoi, Kazuhito; Kotoku, Tetsuo; Komoriya, Kiyoshi

123

Hair casts.  

Science.gov (United States)

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. PMID:25396168

Parmar, Sweta S; Parmar, Kirti S; Shah, Bela J

2014-10-01

124

Anodization of cast aluminium alloys produced by different casting methods  

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

K. Labisz

2008-08-01

125

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

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

A Hodži?

2013-03-01

126

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

Science.gov (United States)

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

Wong, R S; Sims, M R

1987-01-01

127

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

Science.gov (United States)

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

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

2014-10-01

128

Casting methods  

Science.gov (United States)

A casting device includes a covered crucible having a top opening and a bottom orifice, a lid covering the top opening, a stopper rod sealing the bottom orifice, and a reusable mold having at least one chamber, a top end of the chamber being open to and positioned below the bottom orifice and a vacuum tap into the chamber being below the top end of the chamber. A casting method includes charging a crucible with a solid material and covering the crucible, heating the crucible, melting the material, evacuating a chamber of a mold to less than 1 atm absolute through a vacuum tap into the chamber, draining the melted material into the evacuated chamber, solidifying the material in the chamber, and removing the solidified material from the chamber without damaging the chamber.

Marsden, Kenneth C.; Meyer, Mitchell K.; Grover, Blair K.; Fielding, Randall S.; Wolfensberger, Billy W.

2012-12-18

129

Nodular cast iron and casting monitoring  

Directory of Open Access Journals (Sweden)

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

S. Pietrowski

2008-10-01

130

Study of the pore structure of ceramics prepared by the slip casting method  

Science.gov (United States)

The porosity of the slip cast Si3N4 is similar to that of pressed Si3N4 formed at 2500 kg/sq cm. The porosity of cast Si oxynitride is equivalent to that of samples stressed at 10,000 kg/sq cm. Crucibles formed from these materials by slip casting have high thermal shock and corrosion resistance.

Guzman, I. Y.; Dobysh, A. V.

1984-01-01

131

The effects of vascularized tissue transfer on re-irradiation  

International Nuclear Information System (INIS)

Purpose: Nowadays, radical re-irradiation of locally recurrent squamous cell carcinoma is being increasingly tried. The process usually involves some form of surgical excision and vascularized tissue transfer followed by re-irradiation. The aim of this study was to examine the extent of protection from the effects of re-irradiation provided by vascularized tissue transfer. Methods and Materials: One hundred Sprague Dawley rats had their left thighs irradiated to a total dose of 72Gy in 8 fractions, one fraction per day, 5 days per week. The rats were then divided into two groups: At 4 months, one half of the rats had 50% of their quadriceps musculature excised and replaced with a vascularized non-irradiated rectus abdominous myocutaneous flap. The other group served as the control. Six months following the initial radiotherapy all rats were then re-irradiated with either 75 or 90% of the original dose. Incidence of necrosis and the extent of necrosis was measured. Microvasculature of control, transplanted muscle and recipient site was studied by micro-corrosion cast technique and histology of cast specimen. tissues were sampled at pre-irradiation and at 2, 6 and 12 months post re-irradiation. Microvascular surface area was measured from the histology of cast specimen. Results: Necrosis in the control group was clinically evident at 6 weeks post re irradiation and by 10 months all rats developed necrosis. Forty per cent of the thigh that received 75% of the original dose on re-irradiation did not develop any necrosis by 13 months. Other groups developed necrosis to variable extents, however a rim of tissue around the graft always survived. The average thickness of surviving tissue was 9mm. (range being 4-25 mm). None of the transferred flap nor re-irradiated recipient quadriceps developed necrosis. Conclusion: 1. Transplanted rectus abdominus myocutaneous flap and undisturbed muscle have similar radiation tolerance. 2. Vascularized myocutaneous flap offers considerable protection against re radiation of the tissue in its proximity 3. Such protected zone may not be sufficient for external beam radiotherapy but could be useful in a single plane interstitial radiotherapy

132

Examination of the corrosion and erosion resistance of metallic cast and wrought materials in stagnant and flowing, highly concentrated sulfuric acid. Final report. [X1 CrNi 25 20; X1 CrNiSi 18 15; X1 CrNiMoNb 28 4 2; NiCr 29 Fe (Nicrofer 6030)]. Untersuchungen zur Korrosions- und Erosionsbestaendigkeit metallischer Guss- und Knetwerkstoffe in ruhender und stroemender hochkonzentrierter Schwefelsaeure. Schlussbericht  

Energy Technology Data Exchange (ETDEWEB)

A number of stainless steels with different microstructures as well as nickel alloys with different alloy variations were subjected to a test loop using a 98,5 to 98,7% sulfuric acid from a sulfuric acid-cast iron plant. In addition, laboratory tests in stagnant sulfuric acid were carried out, some of which under electrochemical control. The temperature range was 100 - 200deg C. Materials with a high chromium content were not influenced by the flow velocity, whereas Si-alloyed austenitic stainless steel 1.4361 showed a better corrosion resistance with rising flow velocity at temperatures between 100 and 150deg C. The nickel alloy 2.4642 could be used without any risk up to 150deg C. The corrosion rates determined were distinctly below 0.1 mm/a. The addition of molybdenum to the nickel alloy increased the corrosion rate, whereas the admixture of tungsten reduced it. The austenitic stainless steel 1.4335 can likewise be regarded as virtually stable above 150deg C. The best corrosion behaviour over the whole temperature range, i.e. a corrosion rate of less than 0.01 mm/a, exhibited only the ferritic stainless steel 1.4575. The stainless cast steel 1.4136 Sonder proved to be a suitable pump material. Light microscopic and scanning electron microscopic examinations indicate a dependency of corrosion on the flow velocity. Signs of erosion corrosion combined with cavitation are particularly observed on materials with a distinct corrosion rate. (orig.) With 27 refs., 9 tabs., 33 figs.

Bruecken, V.; Wallis, E.

1990-11-14

133

Vascular ring  

Science.gov (United States)

Vascular ring is an abnormal formation of the aorta, the large artery that carries blood from the heart to ... Vascular ring is rare. It accounts for less than 1% of all congenital heart problems. The condition occurs as ...

134

Casting materials  

Science.gov (United States)

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

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

2011-06-14

135

Effects of old age on vascular complexity and dispersion of the hepatic sinusoidal network  

Science.gov (United States)

Objectives In old age, there are marked changes in both the structure of the liver sinusoidal endothelial cell and liver perfusion. The objective of this study was to determine whether there are also aging changes in the microvascular architecture and vascular dispersion of the liver that might influence liver function. Methods Vascular corrosion casts and light micrographs of young (4 mths) and old (24 mths) rat livers were compared. Fractal and Fourier analyses, and microcomputed tomography were used. Vascular dispersion was determined from the dispersion number for sucrose and 100 nm microspheres in impulse response experiments. Results Age did not affect sinusoidal dimensions, sinusoidal density or dispersion number. There were changes in the geometry and complexity of the sinusoidal network as determined by Fractal dimension and degree of anisotropy. Conclusions There are small age-related changes in the architecture of the liver sinusoidal network, which may influence hepatic function and reflect broader aging changes in the microcirculation. However sinusoidal dimensions and hepatic vascular dispersion are not markedly influenced by old age. PMID:18386215

Warren, Alessandra; Chaberek, Slawomir; Ostrowski, Kazimierz; Cogger, Victoria C.; Hilmer, Sarah N.; McCuskey, Robert S.; Fraser, Robin; Le Couteur, David G.

2011-01-01

136

About some corrosion mechanisms of AZ91D magnesium alloy  

International Nuclear Information System (INIS)

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

137

Fabrication of bulk metallic glasses by centrifugal casting method  

Directory of Open Access Journals (Sweden)

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

R. Nowosielski

2007-01-01

138

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

Directory of Open Access Journals (Sweden)

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

Z. Stradomski

2010-07-01

139

Enrichment of Casting Surface in Founding Process  

Directory of Open Access Journals (Sweden)

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

J. Szajnar

2007-07-01

140

Thin Wall Iron Castings  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2001-10-31

 
 
 
 
141

Special thermite cast irons  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

Yu. Zhiguts; Kurytnik, I.

2008-01-01

142

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

International Nuclear Information System (INIS)

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)

143

Phase Transformation in Cast Superaustenitic Stainless Steels  

Energy Technology Data Exchange (ETDEWEB)

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

Nathaniel Steven Lee Phillips

2006-12-12

144

Wear resistant steels and casting alloys containing niobium carbide  

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-12-15

145

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2005-09-30

146

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2005-09-30

147

Streptococcus mutans attachment on a cast titanium surface  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. Fou...

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

2009-01-01

148

Use of duplex stainless steel castings in control valves  

Energy Technology Data Exchange (ETDEWEB)

Duplex stainless steels have enjoyed rapidly increasing popularity in recent years. For numerous reasons the availability of these alloys in the cast form has lagged behind the availability of the wrought form. Commercial demand for control valves in these alloys has driven development of needed information to move into production. A systematic approach was used to develop specifications, suppliers and weld procedures. Corrosion, stress corrosion cracking (SCC), sulfide stress cracking (SSC) and hardness results are also presented for several alloys including; CD3MN (UNS J92205), CD4MCu (UNS J93370) and CD7MCuN (cast UNS S32550).

Gossett, J.L. [Fisher Controls International, Inc., Marshalltown, IA (United States)

1996-07-01

149

Fatigue Assessment of Cast Components : Influence of Cast Defects  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Bjo?rkblad, Anders

2008-01-01

150

Corrosion in seawater systems  

International Nuclear Information System (INIS)

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

151

High quality casting materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Pietrowski, S.

2010-01-01

152

Special thermite cast irons  

Directory of Open Access Journals (Sweden)

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.

Yu. Zhiguts

2008-07-01

153

Closed aluminium skeleton casting  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this miclc authors showcd method for rnanuraauring of skeleton castings with continuous cxtcmal surfacc. Wall lhickncss of thcexternal surface was 6 mm. Thc cxprirnental casting was rnanulacturcd in order to verify lhc rcsults of fitling mould cavity which wcreohtaincd by numerical simu tation. Thc alurninosilicarc core was ad to pducc cxpcrimntal aluminum skelaon castings wilhdimensions or (1 15x65~13 6) mm. Expximental casting was manufactured with elevated temperature of mwld (370 K). L...

Dziuba-ka?uz?a, M.; Cholewa, M.

2008-01-01

154

Niobium in steel castings  

International Nuclear Information System (INIS)

Recent developments in large steel node castings are described briefly, and the advantages offered by the use of cast nodes are illustrated. The development of high integrity castings has been made possible by steelmaking developments and developments in foundry technology. This paper describes the metallurgical aspects of the development of nodes, which necessitates deviations from the conventional manufacture of steel castings. The microstructural and mechanical properties attained are compared with those of plates used in fabricated structures

155

Corrosion resistance of Elektron 21 magnesium alloy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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(OH)2 solution.Design/methodology/approach: Solution treatment was performed at 525°C/8h/water, while ageing treatme...

Kie?bus, A.

2007-01-01

156

Casting and Molding  

Science.gov (United States)

This activity was designed for blind learners, but all types of learners can explore the process used to cast and mold molten metal, glass, and plastics. Using gelatin, the learner will work with a variety of molds to create castings. When the shapes are unmolded, the learner can tactually explore the casts.

Blind, Perkins S.

2012-06-26

157

Pitting corrosion  

International Nuclear Information System (INIS)

Pitting corrosion is a kind of electrolytic corrosion by which the surface of a material is locally affected owing to inhomogeneities on the part of the material or medium. The paper deals briefly with questions relating to the importance, to parameters medium or materialwise, influence on production and construction, as well as the general conditions for pitting corrosion. In particular oxygen corrosion in unalloyed and low-alloy steel, and pitting corrosion in ferritic chromium-steel and austenitic chromium-nickel (molybdenum) steel is described. (DG)

158

Casting materials and their application in research and teaching.  

Science.gov (United States)

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

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

2014-04-01

159

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

Directory of Open Access Journals (Sweden)

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

J. Kasi?ska

2008-12-01

160

The corrosion resistance of two non-noble alloys  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2013-01-01

 
 
 
 
161

High temperature corrosion of metals  

International Nuclear Information System (INIS)

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

162

Improved cast stainless steels for shield module applications  

International Nuclear Information System (INIS)

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

163

Primary Crystallization of High Chromium Cast Steel in Metastable Conditions  

Directory of Open Access Journals (Sweden)

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

A. Studnicki

2012-12-01

164

Cast vs. wrought cobalt-chromium surgical implant alloys.  

Science.gov (United States)

The measured tensile and fatigue strengths of wrought and heat-treated cobalt chromium-molybdenum-carbon alloys such as HS21 were found to be more than twice those of as cast alloys of the same composition. The resistance of wrought HS21 to crevice corrosion at metal-Teflon contacts in isotonic salt solution at 37 degrees C was found to be considerably greater than that of cast HS21, wrought HS25, wrought MP35, or 316L stainless steel which are currently used for surgical implants. The increased crevice corrosion resistance and mechanical strength of wrought HS21 as compared to as cast HS21 was attributed to greater chemical and structural homogeneity as well as to finer grain size and distribution of secondary phases. Fabrication of shaped implants from wrought HS21 is possible by techniques currently used for the fabrication of industrial parts from other wrought cobalt-chromium base alloys. PMID:1176476

Devine, T M; Wulff, J

1975-03-01

165

Corrosion inhibition  

Energy Technology Data Exchange (ETDEWEB)

This invention relates to corrosion-inhibiting compositions and a method of inhibiting corrosion of metallic surfaces in aqueous systems. In particular, it relates to a corrosion-inhibiting composition consisting of a water-soluble hydroxyamine phosphate ester or a water-soluble derivative of it, together with a water-soluble zinc salt and water-soluble 1,2,3-triazole or a water-soluble derivative. It also refers to methods for inhibiting corrosion of metallic surfaces in aqueous systems by adding such compositions to the aqueous medium flowing in such systems. (28 claims)

1975-04-16

166

Corrosion damage of welded steel 17247  

International Nuclear Information System (INIS)

Corrosion effects arising from welded joints of austenitic steel CSN (Czechoslovak Standard) 17247 were studied. Test specimens were taken from two heats; the one had standard chemical composition, whereas the other had elevated titanium content, viz. nearly twelvefold the carbon content. The samples were welded without preheating by manual arc welding, and successively exposed to two corrosion media: 10% ferric chloride, and a solution of copper sulfate and sulfuric acid in distilled water containing copper filings. The corrosion effect depended substantially on the previous surface finishing. Conventionally finished samples exhibited the highest corrosion resistance, electrolytically polished samples followed, whereas samples treated by cast iron grit blasting displayed the lowest resistance. Neither the base material nor the weld material exhibited tendency to intergranular corrosion in sulfuric acid. In ferric chloride solution, the weld material was only slightly affected with respect to the base material. (Z.M.). 11 refs

167

Stereometry specification of anodisation surface of casting aluminium alloys  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The aim of the work is presents the influence of casting method and anodic treatment parameters on properties of an anodic layer formed on aluminum casting alloys.Design/methodology/approach: Investigations were carried out on the laser profile measurement gauge MicroProf from company FRT on two casting aluminum alloys which both were founding by pressure die casting and gravity casting.Findings: The researches included analyze of the influence of chemical composition, geometry and roughness of anodic layer obtained on aluminum casts.Research limitations/implications: Contributes to research on anodic layer for aluminum casting alloys.Practical implications: Conducted investigations lay out the areas of later researches, especially in the direction of the possible, next optimization anodization process of aluminum casting alloys, e.g. in the range of raising resistance on corrosion.Originality/value: The range of possible applications increases for example as materials on working building constructions, elements in electronics and construction parts in air and motorization industry in the aggressive environment.

J. Konieczny

2008-04-01

168

New casting coatings  

International Nuclear Information System (INIS)

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

169

Vascular sarcomas.  

Science.gov (United States)

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

Ravi, Vinod; Patel, Shreyaskumar

2013-08-01

170

Gross anatomy and arterial vascularization of the tympanic cavity and osseous labyrinth in mid-gestational bovine fetuses.  

Science.gov (United States)

This study aims to determine morphological features of certain aural formations, varietal characteristics, and arterial supply in fetal development period in cattle. For this purpose, ears of 10 bovine fetuses in mid-gestation were evaluated. Organ morphology and vascularization in prenatal life were investigated by using corrosion cast technique. It was observed that some aspects of osseous formation and vascular organization in middle and inner ears were not developed completely in the first half of gestation; in addition, cochlea did not its snail-like structure yet, lateral semicircular canal was rather low compared to others and auditory ossicles did not take its final shape. The feeding blood vessels of inner ear were found to demonstrate three different distribution patterns, whereas feeding pattern in middle ear was very similar in many specimens. The presence of stapedial artery was also identified. Differences and similarities with other some species were assessed in terms of both general morphological structure and vascular organization. From this regard, it is thought that this study will constitute a comparative model for both humans and other species and provide morphological contributions since there is not sufficient literature on species-specific ear morphology in the field of veterinary anatomy in contrast to the abundance of studies on humans. PMID:21046670

Erdogan, Serkan; Kilinc, Mehmet

2010-12-01

171

Fireside Corrosion  

Energy Technology Data Exchange (ETDEWEB)

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

Holcomb, Gordon

2011-07-14

172

Erosion corrosion  

International Nuclear Information System (INIS)

In components of plants whose purpose is to convey media specific types of corrosion are frequently noted at higher velocities of flow among which erosion corrosion plays an important part. It may occur in chemical process plant, machinery, hydraulic plants and specially also in power plants where more substantial material denudation and resulting damage from erosion corrosion is liable to take place in steam generator pipes, preheaters, condensers, turbine casings and pumps. The actual failure of component parts is not infrequently preceded by serious damage in downstream parts of plant that are due to heat-accumulating depositions from corrosion products being brought in. Such damage is as a rule accompanied by a cut in power plant performance through increased loss of pressure and reduced heat transition. Sound knowledge of the mechanism and laws governing corrosion is necessary to reduce the risks associated with damage in operating plants, but especially also in designing new plants. (orig./HP)

173

MicroCT scanner performance and considerations for vascular specimen imaging  

International Nuclear Information System (INIS)

Obtaining three-dimensional geometrical data of vascular systems is of major importance to a number of research areas in medicine and biology. Examples are the characterization of tumor vasculature, modeling blood flow, or genetic effects on vascular development. The performance of the General Electric Medical Systems MS8 microCT scanner is examined in the context of these applications. The system is designed to acquire high-resolution images of specimens up to 5 cm in diameter. A maximum resolution of 38 lp/mm at the 10% modulation transfer function level or 22 ?m full width at half maximum of the plane spread function can be achieved with 8.5 ?m voxels and a 17 mm field of view. Three different contrast agents are discussed and applied for imaging of small animal vasculature: corrosion casting material Batson's No. 17 with an added lead pigment, silicon rubber MICROFIL MV122, and a suspension of barium sulfate (Baritop) in gelatin. Contrast for all of these agents was highly variable in different vessels as well as within the same vessel. Imaging of PMMA tubing filled with MICROFIL shows that even vessels below 20 ?m in diameter are detectable and that diameter estimation of vessels based on thresholding is possible with a precision of 2-3 pixels

174

Cool Cast Facts  

Science.gov (United States)

... parent right away if your cast gets any cracks. This can happen if it's hit or crushed, has a weak spot, or if the injured area begins to swell underneath. Your parent will call the doctor. If you notice the cast is causing your fingers or toes to turn white, purple, or blue, tell a ...

175

Closed aluminium skeleton casting  

Directory of Open Access Journals (Sweden)

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

M. Dziuba-Ka?u?a

2008-03-01

176

Bimetallic layer castings  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: In paper is presented technology of bimetallic layer casting in configuration: working part (layer from ferritic or austenitic alloy steel and bearing part from grey cast iron.Design/methodology/approach: In applied technology surface layer on the basis of alloy steel at 2 or 5mm thickness was put directly in founding process of cast iron with use of preparation of mould cavity method. Quality of bimetallic layer castings was estimated on the base of ultrasonic non-destructive testing and examination of the structure and selected usable properties i.e. hardness.Findings: The results of studies and their analysis show efficiency of new, innovative technology of heat-resisting layer castings.Research limitations/implications: In further research, authors of this paper are going to application of different type of alloy steels on working part (layer of bimetallic casting.Practical implications: On the basis of research results was affirmed that application of thinner plates i.e. about thickness 2mm causes their deformation in time of pouring, what disqualify this layer casting for industrial application. Considerably best results was obtained with use thickness of plate 5mm.Originality/value: The value of this paper resides in new effective method of manufacture of heat-resisting castings, mainly for lining of quenching car to coke production.

M. Cholewa

2010-11-01

177

External corrosion  

Energy Technology Data Exchange (ETDEWEB)

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.

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

178

Corrosion and corrosivity monitoring system  

Science.gov (United States)

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

Braunling, Russ; Dietrich, Paul

2005-05-01

179

Polarization Behavior of Squeeze Cast Al2O3 Fiber Reinforced Aluminum Matrix Composites  

International Nuclear Information System (INIS)

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

180

The spheroidisation of VC carbides in high- vanadium cast iron  

Directory of Open Access Journals (Sweden)

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

M. Kawalec

2011-07-01

 
 
 
 
181

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

DEFF Research Database (Denmark)

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

Ambat, Rajan

2000-01-01

182

CASTE FRAMEWORK AT NATIONAL LEVEL  

Directory of Open Access Journals (Sweden)

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

PRAKASH PAWAR

2013-04-01

183

Clean Metal Casting; FINAL  

International Nuclear Information System (INIS)

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

184

Internal corrosion  

Energy Technology Data Exchange (ETDEWEB)

Integrity management processes must accommodate changes in governing regulations. This workshop provided a forum for the discussion of issues related to gas transmission and liquid pipelines carrying oil sands products. Attendees included internal corrosion management specialists, midstream and transmission gas and liquid pipeline operators, as well as chemical treatment users and suppliers. The workshop was divided into 3 sessions: (1) a reprise of previous workshop issues related to gas transmission systems; (2) owner/operator issues associated with oil sands product pipelines; and (3) oil sands product pipelines chemical treatment primer. Issues discussed in the sessions included under-deposit corrosion; hydrogen sulfide (H{sub 2}S) environments; and contaminants. Corrosion models were reviewed, and product specification, sampling and analysis techniques were reviewed. The session also included a discussion of in-line inspection, chemical treatment, and corrosion coupon monitoring techniques. The workshop concluded with a discussion of chemical treatment options for oil sands product pipelines. tabs., figs.

Melvin, B. [EMS Canada, Calgary, AB (Canada); Nguyen, N.; Place, T. [Kinder Morgan Canada Inc., Calgary, AB (Canada)] (comps.)

2009-07-01

185

Corrosion Behavior of Magnesium Alloy AP65 in 3.5% Sodium Chloride Solution  

Science.gov (United States)

Magnesium alloy AP65 was prepared by melting and casting. The corrosion behavior of the as-cast and solid solution (T4)-treated AP65 alloys in 3.5% sodium chloride solution was investigated by corrosion morphology observation, immersion test, and electrochemical measurements. The results show that the second phase Mg17Al12 surrounded by a lead-enriched area distributes discontinuously along the grain boundaries in the as-cast AP65 alloy. The lead-enriched areas with high activity are susceptible to be attacked during immersion test and can act as places for preferential anodic dissolution. The corrosion resistance of the as-cast AP65 alloy can be improved after T4 treatment and the T4-treated alloy suffers general corrosion.

Wang, Nai-guang; Wang, Ri-chu; Peng, Chao-qun; Feng, Yan

2012-07-01

186

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

Directory of Open Access Journals (Sweden)

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

L. Reimann

2013-03-01

187

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2013-01-01

188

Symptomatic stent cast.  

LENUS (Irish Health Repository)

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

Keohane, John

2012-02-03

189

Fighting Corrosion  

Science.gov (United States)

Reinforced concrete structures such as bridges, parking decks, and balconies are designed to have a service life of over 50 years. All too often, however, many structures fall short of this goal, requiring expensive repairs and protection work earlier than anticipated. The corrosion of reinforced steel within the concrete infrastructure is a major cause for this premature deterioration. Such corrosion is a particularly dangerous problem for the facilities at NASA s Kennedy Space Center. Located near the Atlantic Ocean in Florida, Kennedy is based in one of the most corrosive-prone areas in the world. In order to protect its launch support structures, highways, pipelines, and other steel-reinforced concrete structures, Kennedy engineers developed the Galvanic Liquid Applied Coating System. The system utilizes an inorganic coating material that slows or stops the corrosion of reinforced steel members inside concrete structures. Early tests determined that the coating meets the criteria of the National Association of Corrosion Engineers for complete protection of steel rebar embedded in concrete. Testing is being continued at the Kennedy's Materials Science Beach Corrosion Test Site.

2004-01-01

190

Internal corrosion  

Energy Technology Data Exchange (ETDEWEB)

Working Group 11 identified internal corrosion issues in both upstream and downstream oil and gas pipelines and suggested ways to address them through integrity management, modeling, and monitoring. Three sessions were held in an effort to provided a better understanding between integrity professionals engaged in different aspects of pipeline management. Opportunities for reducing cost or improving integrity performance of the whole system were also identified. It was determined that management support is needed in order to monitor and mitigate internal corrosion of pipelines. The role of regulations in ensuring pipeline integrity was also discussed along with rules for pigging and batching of inhibitors. In-line inspections have identified under-deposit corrosion and solids/water deposition as two key problems facing pipeline operators. It was noted that an internal corrosion course offered by the National Association of Corrosion Engineers (NACE) is being well attended and is providing worthwhile training. Other issues discussed by this working group were: bacteria with upstream problems; effects of carbon dioxide, hydrogen sulphide and partial pressures on corrosion; and, procedures and guidelines to maintain clean pipelines. tabs., figs.

Joosten, M. [ConocoPhillips, Bartlesville, OK (United States); Anderson, W. [Spectra Energy Transmission, Vancouver, BC (Canada)

2007-07-01

191

Bainite obtaining in cast iron with carbides castings  

Directory of Open Access Journals (Sweden)

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

S. Pietrowski

2010-01-01

192

Bainite obtaining in cast iron with carbides castings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Pietrowski, S.; Gumienny, G.

2010-01-01

193

Influence of continuous casting conditions on grey cast iron structure  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Szajnar, J.; Stawarz, M.; Wro?bel, T.; Sebzda, W.; Grzesik, B.; Ste?pien?, M.

2010-01-01

194

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

Energy Technology Data Exchange (ETDEWEB)

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.

Lee, J.H.; Atkins, J.E.; Andrews, R.W. [INTERA, Inc./CRWMS M& O, Las Vegas, NV (United States)

1995-12-31

195

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

International Nuclear Information System (INIS)

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

196

Thin Wall Iron Castings; FINAL  

International Nuclear Information System (INIS)

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

197

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

Science.gov (United States)

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

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

2007-09-01

198

A method of improving the soundness of lead-free bronze casting  

International Nuclear Information System (INIS)

The paper describes an investigation into the effect of adding bismuth in cast bronzes for the production of sound casting without segregation. The materials are widely used for sand castings required to resist pressure and to have good corrosion resistance and good bearing properties. Their main applications are therefore in water and oil service parts such as water pipe joints, valves, pump bodies and as bearing shells for heavy duty. In spite of the excellent casting characteristics of these alloys, castings tend to be porous. This property causes leakage under pressure and mechanical weakness and the causes and control of the defect have been investigated. The results indicate that bismuth improves the soundness and mechanical properties of the tin bronze castings as compared to leaded gun metals. (author)

199

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

International Nuclear Information System (INIS)

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

200

Cast iron zinc galvanizing improved by high temperature oxidation process  

Directory of Open Access Journals (Sweden)

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

D. J?drzejczyk

2010-11-01

 
 
 
 
201

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

Directory of Open Access Journals (Sweden)

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

M. Cholewa

2008-10-01

202

Seal welded cast iron nuclear waste container  

Science.gov (United States)

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.

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

1987-01-01

203

External corrosion  

Energy Technology Data Exchange (ETDEWEB)

Working Group 9 discussed external corrosion issues facing the oil and gas pipeline industry. It also reviewed the movement to make cathodic protection (CP) workers a designated occupation in Alberta. Recent changes in CP training, practices and procedures that make the industry safer were outlined along with the application of new technologies such as GPS interrupters and remote monitoring techniques that gather and interpret external corrosion data. Corrosion control coordinators, energy company operators and CP service providers also discussed new advances that are needed to improve the quality of CP data collection and monitoring, including the use of remote and automated CP data collection. The standardized training and qualification that CP workers will require in Alberta in the future was also reviewed along with the newly created guide by the Canadian Association of Petroleum Producers for electrical installations for impressed current CP systems. tabs., figs.

Worthingham, B.; Woloschuk, B. [TransCanada PipeLines Ltd., Calgary, AB (Canada); Zadery, D. [Cimarron Integrity Ltd., Calgary, AB (Canada); Revie, W. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Materials Technology Lab

2007-07-01

204

External corrosion  

Energy Technology Data Exchange (ETDEWEB)

This working group discussed issues related to AC corrosion in pipelines. AC voltage modelling and mitigation processes were reviewed, and cathodic protection (CP) performance on modern coatings were investigated. The sessions were attended by corrosion control coordinators and CP consultants, service providers and suppliers. AC mitigation technologies were discussed. The group was divided into 2 sessions: (1) an update from the 2007 session on AC corrosion and AC voltage mitigation; and (2) modern pipeline construction and CP performance. A case study of CP on high performance coatings was presented. Pipeline facility design practices and their impact on CP were discussed, and an overview of AC mechanisms, testing and troubleshooting practices was provided. tabs., figs.

Worthingham, B. [TransCanada PipeLines Ltd., Calgary, AB (Canada); Zadery, D. [Cimarron Engineering Ltd., Calgary, AB (Canada)] (comps.)

2009-07-01

205

Potentiodynamic Polarization Aspects of the As-cast and Sprayed Al-Si, Al-Sn and Al-Sn-Si Alloys in a Sodium Chloride Solution  

Science.gov (United States)

The present study compares the corrosion behavior of Al-Sn, Al-Si and Al-Sn-Si alloys processed by spray forming with that of the conventional chill cast ones in aqueous 0.1 N NaCl solution. Spray forming resulted in finer microstructural features with uniform distribution of second-phase particles. The spray formed Al-Si samples showed improved corrosion resistance as compared to the chill cast ones. The Sn containing alloys showed inferior corrosion resistance in the neutral electrolyte. The addition of 12.5 wt.% Si to Al-Sn alloys improves the corrosion resistance.

Anil, M.; Balaji, S.; Upadhyaya, A.; Ghosh, M. K.; Ojha, S. N.

2010-12-01

206

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Ramesh Chowdhary; Rao, Srinivasa B.

2011-01-01

207

Corrosion behaviour of solution nitrided stainless steels  

International Nuclear Information System (INIS)

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

208

Continuous Casting for Aluminum Sheet: a Product Perspective  

Science.gov (United States)

Continuous casting processes have been used successfully for more than 50 years to reduce the cost of manufacturing a variety of aluminum rolled products. Approximately 25% of North American flat-rolled sheet and foil is sourced from twin-roll cast or slab cast processes. Twin roll-casters provide a cost-effective solution for producing foil and light-gauge sheet from relatively low-alloyed aluminum (1xxx and 8xxx alloys). Slab casters, particularly Hazelett twin-belt machines, are well utilized in the production of 3xxx or 5xxx painted building products which require moderate strength and good corrosion resistance. Both foil and painted sheet are cost-sensitive commodity products with well-known metallurgical and quality requirements. There have been extensive trials and modest successes with continuous cast can stock and automotive sheet. However, they have not been widely adopted commercially due to generally lower levels of surface quality and formability compared with sheet produced from scalped direct chill (DC) cast ingot. The metallurgical requirements for can and auto sheet are considered in more detail with emphasis on the microstructural features which limit their application, e.g., particle distribution, grain size, and texture. Looking forward, slab casting offers the most viable opportunity for producing strong (i.e., higher alloy content), formable structural auto sheet with acceptable surface quality.

Sanders, Robert E.

2012-02-01

209

Metals corrosion. Passivity and localised corrosion  

International Nuclear Information System (INIS)

Corrosion is the destructive action exerted by the environment on metals. It raises important technical and economical problems with the transformation each year of tenths of million tons of steel into rust (about 5% of the steel used in the entire world). This book proposes solutions to all corrosion situations, even at the design stage to find the most suitable material for a given environment, or in service when tests, expertise and improvements have to be implemented. Several schemes and concrete examples are used to illustrate the different situations. Contents: 1 - aqueous corrosion of metals and alloys: corrosion phenomena, metal properties, water properties; 2 - corrosion electrochemistry: electrochemical nature of corrosion phenomena, thermodynamics of electrochemical reactions, corrosion reaction kinetics; 3 - passivity and passivity rupture: passivity phenomenon, physics of passive films, stainless steels; 4 - localized corrosion: localized corrosion phenomena, pitting corrosion, crevice corrosion

210

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

International Nuclear Information System (INIS)

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

211

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

International Nuclear Information System (INIS)

Prior to disposal in crystalline formations it is planned to enclose vitrified highly radioactive waste from nuclear power plants in metallic containers ensuring their isolation from the groundwater for at least 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)

212

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

Directory of Open Access Journals (Sweden)

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

R. Jasionowski

2011-04-01

213

Streptococcus mutans attachment on a cast titanium surface  

Scientific Electronic Library Online (English)

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

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

2009-03-01

214

Streptococcus mutans attachment on a cast titanium surface  

Directory of Open Access Journals (Sweden)

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.

Sicknan Soares da Rocha

2009-03-01

215

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

Science.gov (United States)

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

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

2011-06-01

216

Continuous roll casting of aluminium alloys – casting parameters analysis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2010-01-01

217

Anodization of cast aluminium alloys produced by different casting methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2008-01-01

218

Corrosion/95 conference papers  

International Nuclear Information System (INIS)

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

219

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Chaturvedi T

2009-01-01

220

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

Energy Technology Data Exchange (ETDEWEB)

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 250/sup 0/C). 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 /sup 60/Co gamma radiation field at dose rates up to 2 x 10/sup 6/ 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 300/sup 0/C; and fatigue crack growth rate studies at ambient pressure and 90/sup 0/C. 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.

Westerman, R.E.; Pitman, S.G.; Nelson, J.L.

1982-09-01

 
 
 
 
221

Aqueous Corrosion Characteristics of Nickel Aluminides  

International Nuclear Information System (INIS)

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

222

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

Directory of Open Access Journals (Sweden)

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

Leszek A. Dobrza?ski

2011-09-01

223

Corrosion behavior of thixomolded Mg-Al alloys  

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-07-01

224

Electroradiography of cast products  

International Nuclear Information System (INIS)

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

225

Wear resistance of cast iron  

Directory of Open Access Journals (Sweden)

Full Text Available 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.

S. Pietrowski

2008-10-01

226

Mix/Cast Contamination Control  

Science.gov (United States)

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

Wallentine, M.

2005-01-01

227

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

Science.gov (United States)

Dental casting alloys are widely used in contact with oral tissue for many years now. With the development of new dental alloys over the past 15 years, many questions remain unanswered about their biologic safety. Concepts and current issues concerning the response to the biologic effects of dental casting alloys are presented. In this paper, samples of three commercially available nickel-chrome (Ni-cr) casting alloys (Dentaurum, Bego, Sankin) were taken to assess their corrosion behavior, using potentiodynamic polarization method (electrochemical method) with fusayama artificial saliva as an electrolyte medium to check for their biocompatibility. The parameters for corrosion rate and corrosion resistance were obtained from computer-controlled corrosion schematic instrument, namely, potentiostat through corrosion software (power CV). The results obtained were analyzed by classic Tafel analysis. Statistical analysis was done by Student's t-test and ANOVA test. It was concluded that Dentarum and Bego showed satisfactory corrosive behavior, with exception of Sankin which depicted higher corrosion rate and least resistance to corrosion. Thus, the selection of an alloy should be made on the basis of corrosion resistance and biologic data from dental manufactures. PMID:21461232

Rao, Srinivasa B.; Chowdhary, Ramesh

2011-01-01

228

Characterization of Al-Mn particles in AZ91D investment castings  

International Nuclear Information System (INIS)

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

229

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

Directory of Open Access Journals (Sweden)

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

M. Gajewski

2012-12-01

230

Influence of continuous casting conditions on grey cast iron structure  

Directory of Open Access Journals (Sweden)

Full Text Available 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 scanning electron microscope and investigations of usable properties i.e. measurements of hardness and machinability.Findings: The results of investigations and their analysis show possibility of unification of flake graphite morphology in cast iron structure, and distribution of hardness on cross-section of ingot and its machinability.Research limitations/implications: In further research, authors of this paper are going to application of introduced method of continuous casting with use of electromagnetic field in industrial tests.Practical implications: The work presents method of unification of structure and properties, which are particularly important in continuous casting. Uniform morphology of flake graphite in structure of cast iron ingots for automobile industry is very important in viewpoint of machinability.Originality/value: Contributes to improvement in quality of grey cast iron continuous casted ingots.

J. Szajnar

2010-03-01

231

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

Science.gov (United States)

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

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

2014-09-01

232

Control of cast iron and casts manufacturing by Inmold method  

Directory of Open Access Journals (Sweden)

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

S. Pietrowski

2009-07-01

233

Corrosion of ferrous materials in a basaltic environment  

International Nuclear Information System (INIS)

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

234

EVALUATION OF SILICATE AND PHOSPHATE COMPOUNDS FOR CORROSION CONTROL  

Science.gov (United States)

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...

235

Vascular Access for Hemodialysis  

Science.gov (United States)

... participants with newly placed fistulas to study the influence of vascular anatomy, vascular biology, patient factors, and ... or 212–889–2210 Fax: 212–689–9261 Internet: www.kidney.org For a copy of the ...

236

Society for Vascular Medicine  

Science.gov (United States)

... about it! New! Information for Patients from Vascular Medicine August 2014 The post-thrombotic syndrome More info ... Job Alerts. Trending Now: Hot Topics in Vascular Medicine Video Series! Fibromuscular Dysplasia (FMD) with Drs. Jeffrey ...

237

Precision cast vs. wrought superalloys  

Science.gov (United States)

While cast polycrystalline superalloys recommend themselves in virtue of better 'buy-to-fly' ratios and higher strengthening gamma-prime volume fractions than those of wrought superalloys, the expansion of their use into such critical superalloy applications as gas turbine hot section components has been slowed by insufficient casting process opportunities for microstructural control. Attention is presently drawn, however, to casting process developments facilitating the production of defect-tolerant superalloy castings having improved fracture reliability. Integrally bladed turbine wheel and thin-walled turbine exhaust case near-net-shape castings have been produced by these means.

Tien, J. K.; Borofka, J. C.; Casey, M. E.

1986-01-01

238

Corrosion behavior of carbon steels under tuff repository environmental conditions  

International Nuclear Information System (INIS)

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

239

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

International Nuclear Information System (INIS)

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

240

AMCC casting development, volume 2  

Science.gov (United States)

PCC successfully cast and performed nondestructive testing, FPI and x-ray, on seventeen AMCC castings. Destructive testing, lab analysis and chemical milling, was performed on eleven of the castings and the remaining six castings were shipped to NASA or Aerojet. Two of the six castings shipped, lots 015 and 016, were fully processed per blueprint requirements. PCC has fully developed the gating and processing parameters of this part and feels the part could be implemented into production, after four more castings have been completed to ensure the repeatability of the process. The AMCC casting has been a technically challenging part due to its size, configuration, and alloy type. The height and weight of the wax pattern assembly necessitated the development of a hollow gating system to ensure structural integrity of the shell throughout the investment process. The complexity in the jacket area of the casting required the development of an innovative casting technology that PCC has termed 'TGC' or thermal gradient control. This method of setting up thermal gradients in the casting during solidification represents a significant process improvement for PCC and has been successfully implemented on other programs. The alloy, JBK75, is a relatively new alloy in the investment casting arena and required our engineering staff to learn the gating, processing, and dimensional characteristics of the material.

1995-01-01

 
 
 
 
241

Wear: Corrosion and erosion  

Science.gov (United States)

The various forms of corrosion are discussed and the role of localized electrochemical reactions in the wear of sliding surfaces are considered. It is stated that there is evidence that fretting corrosion, stress corrosion cracking, corrosion fatigue, and erosion corrosion have as a common basis the localized electrochemical reactions caused by a combination of the induced homogeneity of the surfaces and the corrosive environment. Several processes leading to erosive wear are discussed.

Rowe, C. N.

1973-01-01

242

Thermal aging of cast duplex stainless steels  

International Nuclear Information System (INIS)

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

243

Automatic inspection of surface defects in die castings after machining  

Directory of Open Access Journals (Sweden)

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

S. J. ?wi??o

2011-07-01

244

Melting and casting of FeAl-based cast alloy  

Energy Technology Data Exchange (ETDEWEB)

The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

1998-11-01

245

Corrosion/94 conference papers  

International Nuclear Information System (INIS)

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

246

DentalCast  

Science.gov (United States)

DentalCast is a network of Internet radio and video that brings the latest information about dental technology and clinical techniques to your computer or MP3 Player. DentalCast offers both Audio and Video episodes that can be accessed directly from your PC or users can subscribe to either or both audio and video via iTunes. Episodes available include: recognizing sleep apnea patients in your practice; Discussion of how a new dental product comes to the market; video of denture waxup techniques; and Dental Anxiety: An Integrative Approach to Treatment â to name only a few. These video and audio podcasts will be useful to those studying to be in the dental fields as well as for those teaching or practicing.

2008-02-27

247

Volume MLS Ray Casting  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The method of Moving Least Squares (MLS) is a popular framework for reconstructing continuous functions from scattered data due to its rich mathematical properties and well-understood theoretical foundations. This paper applies MLS to volume rendering, providing a unified mathematical framework for ray casting of scalar data stored over regular as well as irregular grids. We use the MLS reconstruction to render smooth isosurfaces and to compute accurate derivatives for high-quality shading ef...

Ledergerber, Christian; Guennebaud, Gael; Meyer, Miriah D.; Bacher, Moritz; Pfister, Hanspeter

2008-01-01

248

Metal casting extended assessments  

International Nuclear Information System (INIS)

In 1997, the Industrial Assessment Center program of the US Department of Energy initiated Extended Assessments as an option for some of their in-plant assessments. Intended for larger, more complex manufacturing facilities, the multi-day Extended Assessment allows the plant assessment team to explore more complex recommendations with the intent of encouraging major process and equipment changes. In this paper the authors describe the results of Extended Assessments at plants in the Metal Casting Industry, one of the DOE Industries of the Future. They visited five plants, two foundries and three die casting plants, with combined annual sales of $134 million and a combined annual production volume of 35,300 tons. The recommendations offered potential savings to each plant of an average $417,000 or 1.5% of average gross sales. A number of generalizations can be observed based on the assessments in the cast metals industry. First is that many of the smaller firms in this industry have been slow to adopt innovative technology. Off the shelf technologies are available that will help these firms reach the 21st Century. The concept of remelt of metal or scrap in the plant is an operation that can be improved. They found approximately two pounds of metal melted for every pound shipped. Finally, many opportunities exist outside of the core plant operations to reduce operating costs

249

Contemporary art casting’s education in Guangdong  

Directory of Open Access Journals (Sweden)

Full Text Available Based on the practical experience of establishing three art casting laboratories in three different colleges of Guangdong, this paper focuses on the development of contemporary art casting’s education. By analyzing the reason for the shortage of professionals nowadays and the characteristics of modern foundry industry in the Pearl River Delta, the authors try to find out what kind of knowledge structures a modern foundry industry professional should have. Then, from the viewpoint of education, the authors introduce how to combine the art casting laboratory and the creative art casting course as a new teaching pattern, on the one hand, to attract more students to study casting technology, on the other hand, to train them to be qualified professionals for the modern foundry industry.

Wu Chunmiao

2012-02-01

250

Bimetallic layered castings alloy steel – carbon cast steel  

Directory of Open Access Journals (Sweden)

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

T. Wróbel

2011-01-01

251

Casting larger polycrystalline silicon ingots  

Energy Technology Data Exchange (ETDEWEB)

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

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

1995-08-01

252

Contemporary art casting’s education in Guangdong  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Wu Chunmiao; Ji Qing

2012-01-01

253

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

International Nuclear Information System (INIS)

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

254

Continuous roll casting of aluminium alloys – casting parameters analysis  

Directory of Open Access Journals (Sweden)

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

E. Krsti? Vukelja

2010-04-01

255

Fracture Mechanisms in Steel Castings  

Directory of Open Access Journals (Sweden)

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.

Z. Stradomski

2013-07-01

256

Stereometry specification and properties of anodization surface of casting aluminium alloys  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The aim of the work is presents the influence of casting method and anodic treatment parameters on properties, thickness and structure of an anodic layer formed on aluminium casting alloys.Design/methodology/approach: Investigations were carried out on the laser profile measurement gauge MicroProf from company FRT, abrasive wear test was made with using ABR-8251 equipment delivered by TCD Teknologi ApS and microstructure investigations were made with using a light microscope equipped with an electronic camera configured with a computer on two casting aluminium alloys which both were founding by pressure die casting and gravity casting.Findings: The researches included analyze of the influence of chemical composition, geometry, roughness and abrasive wear resistant of anodic layer obtained on aluminium casts.Research limitations/implications: Contributes to research on anodic layer for aluminium casting alloys.Practical implications: Conducted investigations lay out the areas of later researches, especially in the direction of the possible, next optimization anodization process of aluminium casting alloys, e.g. in the range of raising resistance on corrosion.Originality/value: The range of possible applications increases for example as materials on working building constructions, elements in electronics and construction parts in air and motorization industry in the aggressive environment.

L.A. Dobrza?ski

2008-09-01

257

Cast dielectric composite linear accelerator  

Science.gov (United States)

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

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

2009-11-10

258

Corrosion resistance of Mg-RE-Zr alloys  

Directory of Open Access Journals (Sweden)

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

A. Kie?bus

2007-03-01

259

Skeleton castings dynamic load resistance  

Directory of Open Access Journals (Sweden)

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.

M. Cholewa

2013-06-01

260

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

Directory of Open Access Journals (Sweden)

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

Chaturvedi T

2009-01-01

 
 
 
 
261

Corrosion of metals; terms  

International Nuclear Information System (INIS)

The terms of electrochemical corrosion are defined, EC is generally a type of corrosion in which electrochemical processes occur. It only takes course in the presence of an electrolyte. The corrosion need not be immediately caused by an electrolytic abrasion here, it can also be the result of reaction with an electrochemically produced intermediate product (e.g. atomic hydrogen). A characteristic feature of electrochemical corrosion is the dependence of the corrosion procedures on the electrode potential. (orig./LH)

262

Vascular malformations in pediatrics  

International Nuclear Information System (INIS)

Vascular malformations are the cause of nearly all non-traumatic intracranial hemorrhage in children beyond the neonatal stage. Therefore, any child presenting with spontaneous intracranial hemorrhage should be evaluated for child abuse and for vascular malformations. Intracerebral malformations of the cerebral vasculature include vein of Galen malformations, arteriovenous malformation (AVM), cavernomas, dural arteriovenous fistulas, venous anomalies (DVA), and capillary teleangiectasies. Although a few familial vascular malformation have been reported, the majority are sporadic. Clinical symptoms, diagnostic and therapeutic options are discussed. (orig.)

263

Cerebrovascular Casting of the Adult Mouse for 3D Imaging and Morphological Analysis  

Science.gov (United States)

Vascular imaging is crucial in the clinical diagnosis and management of cerebrovascular diseases, such as brain arteriovenous malformations (BAVMs). Animal models are necessary for studying the etiopathology and potential therapies of cerebrovascular diseases. Imaging the vasculature in large animals is relatively easy. However, developing vessel imaging methods of murine brain disease models is desirable due to the cost and availability of genetically-modified mouse lines. Imaging the murine cerebral vascular tree is a challenge. In humans and larger animals, the gold standard for assessing the angioarchitecture at the macrovascular (conductance) level is x-ray catheter contrast-based angiography, a method not suited for small rodents. In this article, we present a method of cerebrovascular casting that produces a durable skeleton of the entire vascular bed, including arteries, veins, and capillaries that may be analyzed using many different modalities. Complete casting of the microvessels of the mouse cerebrovasculature can be difficult; however, these challenges are addressed in this step-by-step protocol. Through intracardial perfusion of the vascular casting material, all vessels of the body are casted. The brain can then be removed and clarified using the organic solvent methyl salicylate. Three dimensional imaging of the brain blood vessels can be visualized simply and inexpensively with any conventional brightfield microscope or dissecting microscope. The casted cerebrovasculature can also be imaged and quantified using micro-computed tomography (micro-CT)1. In addition, after being imaged, the casted brain can be embedded in paraffin for histological analysis. The benefit of this vascular casting method as compared to other techniques is its broad adaptation to various analytic tools, including brightfield microscopic analysis, CT scanning due to the radiopaque characteristic of the material, as well as histological and immunohistochemical analysis. This efficient use of tissue can save animal usage and reduce costs. We have recently demonstrated application of this method to visualize the irregular blood vessels in a mouse model of adult BAVM at a microscopic level2, and provide additional images of the malformed vessels imaged by micro-CT scan. Although this method has drawbacks and may not be ideal for all types of analyses, it is a simple, practical technique that can be easily learned and widely applied to vascular casting of blood vessels throughout the body. PMID:22143104

Walker, Espen J.; Shen, Fanxia; Young, William L.; Su, Hua

2011-01-01

264

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

Directory of Open Access Journals (Sweden)

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

Zhou Jiyang

2011-08-01

265

Colour Metallography of Cast Iron - White Cast Iron (?  

Directory of Open Access Journals (Sweden)

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

Zhou Jiyang

2011-11-01

266

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

Science.gov (United States)

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

Jin, Juntao; Guan, Yuntao

2014-10-01

267

Processing and corrosion control of a magnesium body structure element  

Energy Technology Data Exchange (ETDEWEB)

The hatchback of Volkswagen's 3-liter car (3 1 consumption per 100 km) consists of an inner component of die casting magnesium (AM50) which is covered with an aluminium panel from the outside. This hybrid design normally requires a new manufacturing process: The already pre-coated magnesium part will be bonded and folded with the bare aluminium part. The corrosion protection is provided by an organic coating system which protects both against general corrosion and galvanic corrosion as well. The corrosion of the Al / Mg sandwich has been examined at hybrid samples which are similar to the hatchback. Several powder coatings (epoxy resin, polyester resin, hybrid resin), wet paints and cathodic electro-coating paints of different degrees and compositions have been applied to the magnesium part. They show that only powder coating gives enough protection. Galvanic corrosion at the points of attachment of the hatchback might be possible (for example the bolted joint of the hinge). The resistance against galvanic corrosion has been tested at samples that had a damaged paint coat in order to simulate a defect. Furthermore different contacts (Fe, Al, Zn, etc.) have been fixed conductively. Under laboratory conditions the corrosion load has been made for all test samples with 30 cycles in the environmental corrosion testing. (orig.)

Schreckenberger, H.; Laudien, G. [Volkswagenwerk AG, Wolfsburg (Germany)

2000-07-01

268

The anaerobic corrosion of carbon steel in concrete  

International Nuclear Information System (INIS)

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

269

Phase transformations in cast duplex stainless steels  

Science.gov (United States)

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

Kim, Yoon-Jun

270

Corrosion/96 conference papers  

International Nuclear Information System (INIS)

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

271

Cast iron-base alloy for cylinder/regenerator housing  

Science.gov (United States)

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

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

1985-01-01

272

Scheduled Caste Women: Problems And Challenges  

Directory of Open Access Journals (Sweden)

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

Vijayakumar Murthy

2013-12-01

273

Application of the Evaporative Pattern Casting Process.  

Science.gov (United States)

The Evaporative Pattern Casting process has numerous advantages compared with the conventional bonded-sand casting process. It includes the advantage of requiring no cores, and consequently no casting fin is generated and finishing work is minimized. As a...

A. Yoshikawa, S. Izui

1990-01-01

274

Use of electron microscopy on microstructure characterization of high chromium cast irons  

Directory of Open Access Journals (Sweden)

Full Text Available The physical metallurgy underlying the development of cast microstructures in abrasion resistant high chromium cast irons, and their structural modification by thermal treatments is relatively complex. Structural characterisation via electron microscopy therefore has a key role to play in furthering our understanding of the phase transformations that control the microstructures and hence the service performances of these irons as wear parts. This paper shows how both scanning and especially transmission electron microscopy can provide valuable information on the nature of eutectic and secondary carbides and on the matrix structures in these irons. Particular attention is given to current characterisation research on conventionally cast 30%Cr irons that are used for applications involving corrosive wear e.g. slurry pumps and on a semi-solid cast 27%Cr iron that has a potential for applications in industry.

J.T.H. Pearce

2007-02-01

275

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

International Nuclear Information System (INIS)

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

276

Casting Freedom, 1860-1862  

Science.gov (United States)

Thomas Crawford, an American Sculptor, created the full-size figure of Freedom in clay. Molds were made, from which a full-size positive plaster model was cast in five main sections. This model is on view today in the basement rotunda of the Russell Senate Office Building. Clark Mills was a self-taught American sculptor with experience in casting

Social Education, 2005

2005-01-01

277

Predicting lifetime of cast parts  

Science.gov (United States)

Life expectancy of cast aluminum machine parts can be predicted accurately from fatigue tests at 78 K on notched specimens of aluminum alloy. Method was developed for rocket engine turbopump parts made of high strength, heat treatable alloy with high silicon content; however, technique is applicable to other aluminum casting alloys.

Cooper, R. A.

1980-01-01

278

Colour Metallography of Cast Iron  

Directory of Open Access Journals (Sweden)

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

Zhou Jiyang

2009-05-01

279

Application of isotope dilution for studying corrosion processes in metals  

International Nuclear Information System (INIS)

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)

280

Corrosion-resistant nickel-base alloys for gas turbines  

International Nuclear Information System (INIS)

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

 
 
 
 
281

Corrosion-resistant nickel-base alloys for gas turbines  

Energy Technology Data Exchange (ETDEWEB)

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

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

1976-08-01

282

Corrosion resistance of Elektron 21 magnesium alloy  

Directory of Open Access Journals (Sweden)

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

A. Kie?bus

2007-05-01

283

Stress corrosion cracking and vibration corrosion cracking  

International Nuclear Information System (INIS)

Under certain conditions of stress practically all metallic materials are subject to such cracking corrosion processes. They are much feared because as a rule they are not recognized until the damage - leakage of a container, fracture of a component part-occurs. They may belong to the category of either stress corrosion cracking or vibration corrosion cracking, depending on the different mechanisms of the damage process. As the denominations indicate, one constitutes the interaction between local corrosion attack and mainly static tensile stress (load stress and/or non-load stress) and the other a combination of varying mechanical stress over time and corrosion. Hydrogen-induced cracking is a special form of stress corrosion cracking characterized by trapping of atomic hydrogen in material and subsequent cracking owing to the interaction with mechanical stress. (orig./HP)

284

An evaluation of fiberglass cast application techniques.  

Science.gov (United States)

Cylindrical casts constructed from 2, 3, 4, and 5 inch widths of fiberglass casting material were evaluated for strength in bending using an unstable fracture model. Five-inch casting material produced the strongest casts. The effect of longitudinal splinting with 2-inch fiberglass tape was evaluated in cylindrical casts constructed from 4-inch tape. Casts with splints on the compression side or with splints on both the tension and compression sides were stronger in bending than casts with a single splint on the tension side or casts without splints. PMID:7778250

Wilson, D G; Vanderby, R

1995-01-01

285

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Stradomska, J.

2009-01-01

286

Vascular Intracranial Hypertension  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Iencean, S. M.

2004-01-01

287

Vascular Plant Image Gallery  

Science.gov (United States)

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

Manhart, James R.

288

Kidney Failure and Vascular Disease  

Science.gov (United States)

... Vascular Disease High Blood Pressure and Vascular Disease Kidney Failure and Vascular Disease The kidneys cleanse the blood ... to three times a week to manage their kidney failure. Note: Dialysis requires a surgically-created artery-to- ...

289

The effects of latex additions on centrifugally cast concrete for internal pipeline protection  

Energy Technology Data Exchange (ETDEWEB)

Centrifugally-cast concrete liners applied to the interiors of plain steel pipe sections were tested for corrosion performance in brine solutions. An American Petroleum Institute (API) standard concrete, with and without additions of a styrene-butadiene copolymer latex, was subjected to simulated service and laboratory tests. Simulated service tests used a mechanically pumped test manifold containing sections of concrete-lined pipe. Linear polarization probes embedded at steel-concrete interfaces tracked corrosion rates of these samples as a function of exposure time. Laboratory tests used electrochemical impedance spectroscopy to study corrosion occurring at the steel-concrete interfaces. Electron probe microanalysis (EPMA) determined ingress and distribution of damaging species, such as Cl, in concrete liners periodically returned from the field. Observations of concrete-liner fabrication indicate that latex loading levels were difficult to control in the centrifugal-casting process. Overall, test results indicate that latex additions do not impart significant improvements to the performance of centrifugally cast liners and may even be detrimental. Corrosion at steel-concrete interfaces appears to be localized and the area fraction of corroding interfaces can be greater in latex-modified concretes than in API baseline material. EPMA shows higher interfacial Cl concentration in the latex-modified concretes than in the API standard due to rapid brine transport through cracks to the steel surface.

Buchheit, R.G.; Hinkebein, T.E.; Hlava, P.F. [Sandia National Labs., Albuquerque, NM (United States); Melton, D.G. [LaQue Center for Corrosion Technology, Inc., Wrightsville Beach, NC (United States)

1993-07-01

290

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

International Nuclear Information System (INIS)

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

291

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

International Nuclear Information System (INIS)

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

292

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

Directory of Open Access Journals (Sweden)

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

Delia NICA-BADEA

2012-11-01

293

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

International Nuclear Information System (INIS)

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

294

Modelling of Corrosion Cracks  

DEFF Research Database (Denmark)

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

Thoft-Christensen, Palle

2003-01-01

295

Corrosion inhibiting organic coatings  

Energy Technology Data Exchange (ETDEWEB)

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

Sasson, E.

1984-10-16

296

Die-casting effect on surface characteristics of thin-walled AZ91D magnesium components  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer Depth profile of elements for the die-casting surface layer was studied. Black-Right-Pointing-Pointer The content of C, Si and Fe increases along the molten magnesium filling trace. Black-Right-Pointing-Pointer The outer skin of castings consists of more {beta}-phase and less eutectic {alpha}-phase. Black-Right-Pointing-Pointer The corrosion resistance decreases along the filling trace. - Abstract: Filling trace, filling time and temperature distribution during the die-casting process were simulated using commercial software (MAGMA). The surface microstructure and phase distribution in thin-walled AZ91D magnesium components cast on a hot-chamber die-casting machine were investigated by means of optical microscopy and scanning electron microscopy. The depth profile of alloying elements was examined using a glow discharge optical emission spectrometer. The outer skin microstructure consists of more {beta}-phase and less eutectic {alpha}-phase than the interior region. The elemental content of C, Si, and Fe in the outer skin increased along the filling trace, and they decreased with increasing distance from the surface to the interior region, while the Al had an inverse trend. The corrosion resistance decreased along the filling trace.

Hu Lifang; Chen Shaoping; Miao Yang [Department of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Meng Qingsen, E-mail: mengqingsen@263.net [Department of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China)

2012-11-15

297

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

International Nuclear Information System (INIS)

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

298

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

International Nuclear Information System (INIS)

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

299

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

Science.gov (United States)

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

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

2013-01-01

300

3-Dimensional Resin Casting and Imaging of Mouse Portal Vein or Intrahepatic Bile Duct System  

Science.gov (United States)

In organs, the correct architecture of vascular and ductal structures is indispensable for proper physiological function, and the formation and maintenance of these structures is a highly regulated process. The analysis of these complex, 3-dimensional structures has greatly depended on either 2-dimensional examination in section or on dye injection studies. These techniques, however, are not able to provide a complete and quantifiable representation of the ductal or vascular structures they are intended to elucidate. Alternatively, the nature of 3-dimensional plastic resin casts generates a permanent snapshot of the system and is a novel and widely useful technique for visualizing and quantifying 3-dimensional structures and networks. A crucial advantage of the resin casting system is the ability to determine the intact and connected, or communicating, structure of a blood vessel or duct. The structure of vascular and ductal networks are crucial for organ function, and this technique has the potential to aid study of vascular and ductal networks in several ways. Resin casting may be used to analyze normal morphology and functional architecture of a luminal structure, identify developmental morphogenetic changes, and uncover morphological differences in tissue architecture between normal and disease states. Previous work has utilized resin casting to study, for example, architectural and functional defects within the mouse intrahepatic bile duct system that were not reflected in 2-dimensional analysis of the structure1,2, alterations in brain vasculature of a Alzheimer's disease mouse model3, portal vein abnormalities in portal hypertensive and cirrhotic mice4, developmental steps in rat lymphatic maturation between immature and adult lungs5, immediate microvascular changes in the rat liver, pancreas, and kidney in response in to chemical injury6. Here we present a method of generating a 3-dimensional resin cast of a mouse vascular or ductal network, focusing specifically on the portal vein and intrahepatic bile duct. These casts can be visualized by clearing or macerating the tissue and can then be analyzed. This technique can be applied to virtually any vascular or ductal system and would be directly applicable to any study inquiring into the development, function, maintenance, or injury of a 3-dimensional ductal or vascular structure. PMID:23128398

Walter, Teagan J.; Sparks, Erin E.; Huppert, Stacey S.

2012-01-01

 
 
 
 
301

Strip casting with fluxing agent applied to casting roll  

Science.gov (United States)

A strip caster for producing a continuous strip includes a tundish for containing a melt, a pair of horizontally disposed water cooled casting rolls and devices for electrostatically coating the outer peripheral chill surfaces of the casting rolls with a powder flux material. The casting rolls are juxtaposed relative to one another for forming a pouting basin for receiving the melt through a teeming tube thereby establishing a meniscus between the rolls for forming the strip. The melt is protected from the outside air by a non-oxidizing gas passed through a supply line to a sealing chamber. A preferred flux is boron oxide having a melting point of about 550 C. The flux coating enhances wetting of the steel melt to the casting roll and dissolves any metal oxide formed on the roll. 3 figs.

Williams, R.S.; O`Malley, R.J.; Sussman, R.C.

1997-07-29

302

Vascular Access in Children  

International Nuclear Information System (INIS)

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

303

Pediatric vascular access  

International Nuclear Information System (INIS)

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

304

Pediatric vascular access  

Energy Technology Data Exchange (ETDEWEB)

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.)

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

2006-05-15

305

Localized corrosion information using high resolution measurement devices  

DEFF Research Database (Denmark)

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

Ambat, Rajan

2005-01-01

306

Strip casting apparatus and method  

Science.gov (United States)

Strip casting apparatus including a molten-metal-holding container and a nozzle to deposit molten metal onto a moving chill drum to directly cast continuous metallic strip. The nozzle body includes a slot bounded between a back and a front lip. The slot width exceeds about 20 times the gap distance between the nozzle and the chill drum surface. Preferably, the slot width exceeds 0.5 inch. This method of strip casting minimizes pressure drop, insuring better metal-to-chill-drum contact which promotes heat transfer and results in a better quality metallic strip. 6 figs.

Williams, R.S.; Baker, D.F.

1988-09-20

307

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

Directory of Open Access Journals (Sweden)

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

K Nirmalkumar

2009-02-01

308

The anaerobic corrosion of carbon steel in concrete  

International Nuclear Information System (INIS)

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

309

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

International Nuclear Information System (INIS)

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

310

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

Energy Technology Data Exchange (ETDEWEB)

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)

Hadj-Hassen, F. [Ecole des Mines de Paris - CGES, 77 - Fontainebleau (France); Bienvenu, Y. [Ecole des Mines de Paris, CM, 91 - Evry (France); Noirel, J.F. [Charbonnages de France, DTN, 57 - Freyming Merlebach (France); Metz, M. [charbonnages de France, ESA, 57 - Freyming Merlebach (France)

2005-07-01

311

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2012-01-01

312

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Banerji, Shankha

1992-01-01

313

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

Sn, Supreetha; Ravindra K; Murali H

2010-01-01

314

Corrosion behavior of Au and Ag modified Cu-Ni-Mn alloys.  

Science.gov (United States)

The linear electrochemical polarization method was used to provide quantitative in vitro measurements of corrosion rates as a function of exposure time for Cu-Ni-Mn, Cu-Ni-Mn-Au, Cu-Ni-Mn-Ag, and Cu-Ni-Mn-Au-Ag alloys in artificial saliva. Both Au and Ag additives to dental-cast Cu-Ni-Mn alloys lowered the corrosion rate significantly. PMID:6928420

Wright, S R; Cocks, F H; Gettleman, L

1980-04-01

315

The CAST Time Projection Chamber  

CERN Document Server

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.

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

316

Casting technique for light metal alloy  

International Nuclear Information System (INIS)

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

317

Vascular ring (image)  

Science.gov (United States)

Vascular ring is a term used to describe a number of abnormal formations of the aorta, the large artery ... the pulmonary artery. The abnormal vessel(s) forms a ring, which encircles and may press down on the ...

318

Laser Vascular Lesion Treatment  

Science.gov (United States)

... below medications has been discussed with your doctor): Aspirin Ibuprofen Vitamin E Gingko and ginseng Fish oil supplements Prescription blood-thinning medications (eg, warfarin or heparin) With laser vascular lesion treatment, there are many ...

319

Chameleon foreCAST  

CERN Document Server

Dark energy models, such as the chameleon, where the acceleration of the expansion of the universe results from the dynamics of a scalar field coupled to matter, suffer from the potential existence of a fifth force. Three known mechanisms have been proposed to restore General Relativity in the solar system and the laboratory, which are the symmetron/Damour-Polyakov effect, the Vainshtein property and the chameleon screening. Here, we propose to probe the existence of chameleons in the laboratory, considering their particle physics consequences. We envisage the resonant and non-resonant production of chameleons in the sun and their back-conversion into X-ray photons in a solar helioscope pipe such as the one used by CAST. A detection of these X-rays would indicate the existence of chameleons. We focus on a template model for the solar magnetic field: a constant magnetic field in a narrow shell surrounding the tachocline. The X-ray photons in a helioscope pipe obtained from back-conversion of the chameleons cre...

Brax, Philippe; Zioutas, Konstantin

2011-01-01

320

Virtualisation of casting engineering  

Directory of Open Access Journals (Sweden)

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

J.S. Suchy

2007-09-01

 
 
 
 
321

Treatment of vascular calcification.  

Science.gov (United States)

A variety of potential therapies for vascular calcification, based either on the underlying biology or physical chemistry or solely on empiric observations in patients, may be effective but lack rigorous testing. Pasch et al. provide convincing evidence that sodium thiosulfate prevents medial vascular calcification in uremic rats. Although this provides some scientific basis for the clinical use of thiosulfate, uncertainty about mechanism of action and safety still remains. PMID:19008909

O'Neill, W Charles

2008-12-01

322

Computer aided casting methoding of railway system  

Directory of Open Access Journals (Sweden)

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

St. M. Dobosz

2008-07-01

323

Inoculation of chromium white cast iron  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

Kopycin?ski, D.

2009-01-01

324

Modelling of flow phenomena during DC casting:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Zuidema, J.

2005-01-01

325

Selected properties of new „duplex” cast steel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2011-01-01

326

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

Science.gov (United States)

The microvascularization of the collared peccary (Tayassu tajacu) placenta was studied by vascular casts and immunolocalization of ?-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

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

2012-07-01

327

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

DEFF Research Database (Denmark)

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

Santos, Tatiana Carlesso; Oliveira, Moacir Franco

2012-01-01

328

High-Performance Corrosion-Resistant Iron-Based Amorphous Metals: The Effects of Composition, Structure and Environment on Corrosion Resistance  

Energy Technology Data Exchange (ETDEWEB)

New corrosion-resistant, iron-based amorphous metals have been identified from published data or developed through combinatorial synthesis, and tested to determine their relative thermal phase stability, microstructure, mechanical properties, damage tolerance, and corrosion resistance. Some alloy additions are known to promote glass formation and to lower the critical cooling rate [F. Guo, S. J. Poon, Applied Physics Letters, 83 (13) 2575-2577, 2003]. Other elements are known to enhance the corrosion resistance of conventional stainless steels and nickel-based alloys [A. I. Asphahani, Materials Performance, Vol. 19, No. 12, pp. 33-43, 1980] and have been found to provide similar benefits to iron-based amorphous metals. Many of these materials can be cast as relatively thick ingots, or applied as coatings with advanced thermal spray technology. A wide variety of thermal spray processes have been developed by industry, and can be used to apply these new materials as coatings. Any of these can be used for the deposition of the formulations discussed here, with varying degrees of residual porosity and crystalline structure. Thick protective coatings have now been made that are fully dense and completely amorphous in the as-sprayed condition. An overview of the High-Performance Corrosion Resistant Materials (HPCRM) Project will be given, with particular emphasis on the corrosion resistance of several different types of iron-based amorphous metals in various environments of interest. The salt fog test has been used to compare the performance of various wrought alloys, melt-spun ribbons, arc-melted drop-cast ingots, and thermal-spray coatings for their susceptibility to corrosion in marine environments. Electrochemical tests have also been performed in seawater. Spontaneous breakdown of the passive film and localized corrosion require that the open-circuit corrosion potential exceed the critical potential. The resistance to localized corrosion is seawater has been quantified through measurement of the open-circuit corrosion potential (E{sub corr}), the breakdown potential (E{sub crit}) and the repassivation potential (E{sub rp}). The greater the difference between the open-circuit corrosion potential and the repassivation potential ({Delta}E), the more resistant a material is to modes of localized corrosion such as pitting and crevice corrosion. Cyclic polarization (CP) was used as a means of measuring the critical potential (E{sub crit}) relative to the open-circuit corrosion potential (E{sub corr}). Linear polarization (LP) has been used to determine the corrosion current (i{sub corr}) and the corresponding corrosion rate. Other aspects of the materials will also be discussed, as well as potential applications.

Farmer, J; Choi, J S; Haslam, J; Lian, T; Day, S; Yang, N; Blue, C; Peters, W; Bayles, R; Lewandowski, J; Perepezko, J; Hildal, K; Lavernia, E; Ajdelsztajn, A; Grave, O; Aprigliano, L; Kaufman, L; Boudreau, J; Branagan, D J; Beardsley, B

2006-04-11

329

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

International Nuclear Information System (INIS)

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

330

Corrosion behavior of Ni-based structural materials for electrolytic reduction in lithium molten salt  

Energy Technology Data Exchange (ETDEWEB)

In this study, the corrosion behavior of new Ni-based structural materials was studied for electrolytic reduction after exposure to LiCl-Li{sub 2}O molten salt at 650 deg. C for 24-216 h under an oxidizing atmosphere. The new alloys with Ni, Cr, Al, Si, and Nb as the major components were melted at 1700 deg. C under an inert atmosphere. The melt was poured into a preheated metallic mold to prepare an as-cast alloy. The corrosion products and fine structures of the corroded specimens were characterized by scanning electron microscope (SEM), Energy Dispersive X-ray Spectroscope (EDS), and X-ray diffraction (XRD). The corrosion products of as cast and heat treated low Si/high Ti alloys were Cr{sub 2}O{sub 3}, NiCr{sub 2}O{sub 4}, Ni, NiO, and (Al,Nb,Ti)O{sub 2}; those of as cast and heat treated high Si/low Ti alloys were Cr{sub 2}O{sub 3}, NiCr{sub 2}O{sub 4}, Ni, and NiO. The corrosion layers of as cast and heat treated low Si/high Ti alloys were continuous and dense. However, those of as cast and heat treated high Si/low Ti alloys were discontinuous and cracked. Heat treated low Si/high Ti alloy showed the highest corrosion resistance among the examined alloys. The superior corrosion resistance of the heat treated low Si/high Ti alloy was attributed to the addition of an appropriate amount of Si, and the metallurgical evaluations were performed systematically.

Cho, Soo Haeng, E-mail: nshcho1@kaeri.re.kr [Korea Atomic Energy Research Institute, 1045 Daedeokdaero Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Park, Sung Bin [Korea Atomic Energy Research Institute, 1045 Daedeokdaero Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Lee, Jong Hyeon, E-mail: jonglee@cnu.ac.kr [Graduate School of Green Energy Technology, Chungnam National University, 79 Daehak-ro, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Hur, Jin Mok; Lee, Han Soo [Korea Atomic Energy Research Institute, 1045 Daedeokdaero Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

2011-05-01

331

Surface films and corrosion of copper  

International Nuclear Information System (INIS)

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

332

Surface films and corrosion of copper  

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-03-01

333

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

Directory of Open Access Journals (Sweden)

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

J. Stradomska

2009-07-01

334

Application of hard coatings in aluminium die casting - soldering, erosion and thermal fatigue behaviour  

Energy Technology Data Exchange (ETDEWEB)

In aluminium die casting, tools are exposed to erosion, corrosion and soldering due to the frequent contact of the tool surface to the casting alloy, to heat checking and gross cracking due to thermal fatigue and to oxidation due to high pouring temperatures. The gradual destruction of die surfaces during service decreases casting piece quality and limits die lifetime. Hard coatings based on nitrides or carbides of transition metals may protect the steel surface from erosion and soldering of aluminium and improve the resistance against thermal cracking. Thus, they may replace the thick oxide-based die coatings nowadays used in foundries. Within this study, results obtained on the performance of coatings deposited onto die-casting dies by magnetron sputtering and plasma-assisted chemical vapour deposition are presented and discussed. TiN, Ti(C,N), Ti(B,N), and (Ti,Al)(C,N) coatings deposited onto hot-working tool steel have been evaluated in practical die-casting service. Results obtained are compared with those of simulation tests using thermal cycling immersion tests in liquid aluminium, thermo-gravimetric analysis, and stress measurements during thermal cycling. Maximum lifetime of the coated casting die is achieved for careful optimization of hardness, adhesion, oxidation resistance and high temperature stability, and internal stresses. (orig.)

Mitterer, C.; Holler, F. [Montanuniversitaet Leoben (Austria). Inst. fuer Metallkunde und Werkstoffpruefung; Uestel, F. [Department of Metallurgy and Materials Science, Sakarya University, TR-5400, Adapazari (Turkey); Heim, D. [Ruebig GmbH and Co. KG, Durisolstrasse 12, A-4600, Wels (Austria)

2000-03-01

335

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

Science.gov (United States)

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

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

2013-04-01

336

Grain boundary corrosion of copper canister weld material  

International Nuclear Information System (INIS)

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

337

Oil ash corrosion  

International Nuclear Information System (INIS)

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

338

Development of vacuum die-casting process  

Directory of Open Access Journals (Sweden)

Full Text Available The vacuum die-casting process, started 25 years ago in Japan, has been widely applied. This technology contributes very much to improvement of castings quality. The main factor causing the defects of die castings is the trapped air in the mold cavity, while the key technology of vacuum die-casting process is to avoid the trapped air effectively by evacuating the cavity before casting. At the same time, due to the shot speed and the casting pressure reduced in half, the service life of the die is prolonged and the productivity is enhanced, as well. Vacuum die-casting process is of great signifi cance in improving the die castings quality and making up the shortcomings of super-high-speed shot casting.

Masashi Uchida

2009-05-01

339

Fillability of Thin-Wall Steel Castings  

Energy Technology Data Exchange (ETDEWEB)

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

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

2002-07-30

340

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Kie?bus, A.

2007-01-01

 
 
 
 
341

Vascular nevi in children  

Directory of Open Access Journals (Sweden)

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

Senthilkumar M

2006-01-01

342

Residual stresses in castings produced by press die casting technology  

Directory of Open Access Journals (Sweden)

Full Text Available The influence of technological parameters on residual stresses in pressure die castings is analysed in this paper. In order for the residual stresses to be as low as possible the optimization of technological parameters is necessary. The centrally composed plan of experiment 24cs is used in the investigation. Technologically influencing parameters are changed according to the mentioned plan of experiment and they are: temperature of pouring, rate of die cavity filling with the melt, post pressure in already filled die and the casting cooling time along with the pouring system.

D. Novoselovi?

2015-01-01

343

Metal-matrix corrosion studies in Canadian shield granitic groundwaters  

International Nuclear Information System (INIS)

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

344

Characterization Studies of Mullite Coatings on Cast Aluminum  

Science.gov (United States)

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.

Viswanath, B.; Vijayarangan, S.

2012-03-01

345

Microstructure quantitative analysis of aluminum skeleton castings  

Directory of Open Access Journals (Sweden)

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

M. Cholewa

2008-12-01

346

Research progress on squeeze casting in China  

Directory of Open Access Journals (Sweden)

Full Text Available Squeeze casting is a technology with short route, high efficiency and precise forming, possessing features of casting and plastic processing. It is widely used to produce high performance metallic structural parts. As energy conservation and environmental protection concerns have risen, lightweight and high performance metal parts are urgently needed, which accelerated the development of squeeze casting technology over the past two decades in China. In this paper, research progress on squeeze casting alloys, typical parts manufacturing and development of squeeze casting equipment in China are introduced. The future trend and development priorities of squeeze casting are discussed.

Li Yuanyuan

2014-07-01

347

Aluminide protective coatings on high–temperature creep resistant cast steel  

Directory of Open Access Journals (Sweden)

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

J. Kubicki

2009-10-01

348

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

Directory of Open Access Journals (Sweden)

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

Yanling Ni

2014-07-01

349

CAST Physics Proposal to SPSC  

CERN Document Server

The CAST experiment has the potential to search for solar axions (dark matter particle candidates) or other particles with similar coupling. E.g., paraphtons (Hidden Sector), chameleons (dark energy), while considering the possibility whether CAST could be transformed to an antenna for relic axions with rest mass up to 0.1 to 1meV. While axion searches suggest detectors with lower background, paraphoton and chameleon searches require detectors with sub-keV threshold energy and the use of transparent windows in front of the Micromegas detectors, which cover 3 out of the 4 CAST magnet exits. Ongoing theoretical estimates and experimental investigations will define the priorities of the suggested 4 physics items of this proposal for the period 2012-2014.

CAST, Collaboration

2011-01-01

350

CAST results and Axion review  

CERN Document Server

We present results from the CERN Axion Solar Telescope (CAST) and the Axion Dark Matter eXperiment (ADMX), together with a brief review on prospects on Axion searches with a variety of experimental techniques. CAST has explored masses up to 0.64 eV setting the most stringent limit on the axion-photon coupling, apart for the micro-eV region where ADMX is the most competitive experiment. CAST is aiming at surpassing the 1eV WMAP upper limit and possibly revisiting the operation in vacuum with extra sensitive X-ray detectors, while ADMX, using improved extra sensitive SQUID amplifiers will explore the micro-eV mass range.

Geralis, T

2009-01-01

351

Centrifugal slip casting of components  

International Nuclear Information System (INIS)

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

352

Vascular tumors of bone.  

Science.gov (United States)

Vascular tumors of the bone represent a variety of neoplasms, ranging from benign hemangiomas and epithelioid hemangiomas to intermediate grade hemangioendotheliomas to frankly malignant angiosarcomas. Over the years, there has been considerable debate concerning the aggressivity, nomenclature, and mere existence of various nosologic entities, due to morphologic similarities and uncertainty regarding biologic behavior. Such debate has led to confusion among pathologists and clinicians, thus diminishing the prognostic implications in the diagnosis of these lesions. Here we review the current knowledge concerning the primary vascular neoplasms of the bone and correlate clinicopathologic features with tumor behavior. PMID:24680180

Hart, Jesse L; Edgar, Mark A; Gardner, Jerad M

2014-01-01

353

Corrosion in bioprocessing applications.  

Science.gov (United States)

Corrosion in bioprocessing applications is described for a 25-year-old bioprocessing pilot plant facility. Various available stainless steel alloys differ greatly in properties owing to the impact of specific alloying elements and their concentrations. The alloy property evaluated was corrosion resistance as a function of composition under typical bioprocessing conditions such as sterilization, fermentation, and cleaning. Several non-uniform forms of corrosion relevant to bioprocessing applications (e.g., pitting, crevice corrosion, intergranular attack) were investigated for their typical causes and effects, as well as alloy susceptibility. Next, the corrosion resistance of various alloys to specific bioprocessing-relevant sources of corrosion (e.g., medium components, acids/bases used for pH adjustment, organic acid by-products) was evaluated, along with the impact of temperature on corrosion progression. Best practices to minimize corrosion included considerations for fabrication (e.g., welding, heat treatments) and operational (e.g., sterilization, media component selection, cleaning) approaches. Assessments and repair strategies for observed corrosion events were developed and implemented, resulting in improved vessel and overall facility longevity. PMID:18512080

Junker, Beth

2009-01-01

354

Energy Consumption of Die Casting Operations  

Energy Technology Data Exchange (ETDEWEB)

Molten metal processing is inherently energy intensive and roughly 25% of the cost of die-cast products can be traced to some form of energy consumption [1]. The obvious major energy requirements are for melting and holding molten alloy in preparation for casting. The proper selection and maintenance of melting and holding equipment are clearly important factors in minimizing energy consumption in die-casting operations [2]. In addition to energy consumption, furnace selection also influences metal loss due to oxidation, metal quality, and maintenance requirements. Other important factors influencing energy consumption in a die-casting facility include geographic location, alloy(s) cast, starting form of alloy (solid or liquid), overall process flow, casting yield, scrap rate, cycle times, number of shifts per day, days of operation per month, type and size of die-casting form of alloy (solid or liquid), overall process flow, casting yield, scrap rate, cycle times, number of shifts per day, days of operation per month, type and size of die-casting machine, related equipment (robots, trim presses), and downstream processing (machining, plating, assembly, etc.). Each of these factors also may influence the casting quality and productivity of a die-casting enterprise. In a die-casting enterprise, decisions regarding these issues are made frequently and are based on a large number of factors. Therefore, it is not surprising that energy consumption can vary significantly from one die-casting enterprise to the next, and within a single enterprise as function of time.

Jerald Brevick; clark Mount-Campbell; Carroll Mobley

2004-03-15

355

Corrosion of proposed canister materials in salt repositories  

International Nuclear Information System (INIS)

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

356

Experience with IN 939 as a hot corrosion resistant turbine vane material  

Energy Technology Data Exchange (ETDEWEB)

For stationary gas turbine vanes IN 939 was evaluated very thoroughly in Europe as a promising hot corrosion resistant nickel base alloy. This paper shows examples of properties and behavior of IN 939 from literature and from actual application in stationary gas turbines. After long-term operation in stationary gas turbines vanes are analysed to show the type of oxide scale formation, the hot corrosion attack and phase stability. The alloy IN 939 exhibited excellent hot corrosion resistance under severe environmental conditions comparable to that of commercial hot corrosion protective coatings. Phases are described developed after casting and during heat treatment and sensitivity towards ..gamma..-phase formation is briefly discussed. Creep and fatique data of IN 939 are compared with IN 738 LC as well as the hot corrosion behavior.

Schneider, K.; Bauer, R.; Grunling, H.W.; Staubli, M.

1984-06-01

357

On the role of surface roughness in the corrosion of pure magnesium in vitro.  

Science.gov (United States)

The relationship between surface roughness and degradation behavior in magnesium (Mg) biomaterials is still a controversial issue. This study aims to clarify the relationship between surface roughness and corrosion rate of pure Mg. Pure Mg samples with surface roughness values (Ra) of 0.59, 2.68, and 9.12 ?m were cast using an indirect solid-free form fabrication method. The in vitro corrosion behavior was evaluated using hydrogen evolution, mass loss, potentiodynamic polarization, and electrochemical impedance spectroscopy. It was confirmed that surface roughness had a significant influence on the corrosion rate of pure Mg, with increasing roughness resulting in an accelerated corrosion rate. However, pitting corrosion was not observed, suggesting that surface roughness does not affect the pitting potential of Mg. PMID:22566378

Nguyen, T L; Blanquet, A; Staiger, M P; Dias, G J; Woodfield, T B F

2012-07-01

358

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

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: AE44 magnesium alloy allows attractive high temperature mechanical properties, as well as diecastabilityand good corrosion resistance. It contains magnesium, aluminum, cerium and lanthanum. Typically,it is used in automotive industry for structural components working at elevated temperature (150÷175°C. Theaim of this paper is to present the results of investigations on the microstructure of the AE44 magnesium alloybefore and after hot chamber die casting.Design/methodology/approach: Die casting was carried out on 280 tone locking force hot-chamber die castingmachine. For the microstructure observation, a Olympus GX+70 metallographic microscope and a HITACHIS-3400N scanning electron microscope with a Thermo Noran EDS spectrometer equipped with SYSTEM SIXwere used.Findings: Based on the investigation carried out it was found that the AE44 magnesium alloy before diecasting is characterized by ?-Mg solid solution with globular, lamellar and acicular precipitations of Al11RE3and Al3RE phases. Moreover, there was found globular Mn-rich phase existence (probably Al8CeMn4 phase.After hot-chamber die casting the microstructure of AE44 alloys consist of equiaxed dendrites of ?-Mg withprecipitates of Al11RE3 and probably Al2RE phase.Research limitations/implications: Future researches should contain investigations of the influence of the hotchamber die casting process parameters on the microstructure and mechanical properties of AE44 magnesiumalloy.Practical implications: AE44 magnesium alloy can be cast with cold- and hot-chamber die casting machine.Results of investigation may be useful for preparing die casting technology of this alloy.Originality/value: The results of the researches make up a basis for the investigations of new magnesium alloyscontaining rare earth elements for hot chamber die casting designed to service in elevated temperature.

A. Kie?bus

2007-01-01

359

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

360

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

International Nuclear Information System (INIS)

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

 
 
 
 
361

Corrosion in the oil industry  

Energy Technology Data Exchange (ETDEWEB)

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.

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

362

A Nanotechnology-Based Elastomeric Vascular Graft  

Science.gov (United States)

The biocompatible of a vascular graft can be controlled by the surface composition and texture of the surface. In particular, the surface of a synthetic elastomer can be modified to mimic the functionality of the inner vascular lumen. We will investigate the effect of the texture and surface composition of cross-linked polydimethylsiloxane (PDMS) films on endothelial cell attachment, spreading, and function. The smooth surface, nanometer scale roughness, of thin PDMS films and self-supporting PDMS substrates has been created by spin coating and casting while optical gratings have been employed as stamps for printing texture, micrometer scale stripes of ridges and grooves, onto PDMS substrates. The smooth surface of self-supporting PDMS has been activated and modified with 3-(triethoxysilyl)propylsuccinic anhydride (TESPSA) via self-assemble technique. The attachment of TESPSA is characterized by contact angle and x-ray photoelectron spectroscopy. The RGD peptide is selectively grafted to the TESPSA and then characterized. Endothelial cell behavior is then investigated as a function of surface texture and composition.

Uttayarat, Pimporn; Composto, Russell

2003-03-01

363

Structural Aspects of the Behavior of Lead-Free Solder in the Corrosive Solution  

Science.gov (United States)

In oxidizing environments, most tin-based lead (Pb)-free alloys form a tin oxide that is easily eroded or mechanically damaged, affecting corrosion resistance and thus reliability of the soldered joints. In this study, the effect of microstructure heterogeneity on corrosion behavior of Pb-free solder candidate systems has been investigated on the example of as-cast and heat-treated alloys. The research was focused on a comparison between the corrosion resistance of binary Sn-Zn and ternary Sn-Zn-Cu alloys. Accelerated corrosion tests were performed by means of electrochemical methods in the sodium sulfate solution (VI), Na2SO4, of about 0.5 M concentration, pH adjusted to 2 by means of concentrated H2SO4 acid. In these tests, the corrosion potentials as well as polarization curves were determined for the selected alloys in as-cast state and after their heat treatment using different combinations of processing parameters. The measurements of basic electrochemical characteristics were made, i.e., the corrosion current ( i corr ?A/cm2) and Tafel coefficients, both cathodic ( b c V/dec) and anodic ( b a V/dec) ones. Detailed structural characterization of as-cast and heat-treated alloys before and after accelerated corrosion tests has been made under a wide range of magnifications using light microscopy and scanning electron microscopy observations. The results showed that structural heterogeneity of the examined alloys, attributed to the presence of secondary phases, and affected by their size and distribution, significantly influences the behavior of the examined Pb-free Sn-Zn-based alloys in the corrosive environment.

Pietrzak, K.; Grobelny, M.; Makowska, K.; Sobczak, N.; Rudnik, D.; Wojciechowski, A.; Sienicki, E.

2012-05-01

364

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

International Nuclear Information System (INIS)

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

365

CIR Casting System for making transtibial sockets.  

Science.gov (United States)

This paper describes a new casting system for transtibial socket fabrication. Like the earlier CIR Sand Casting System, the CIR Casting System is based on the 'dilatancy' principle that is similar to the packaging process for coffee beans by which loose beans become a solid mass when a vacuum is applied. The main difference from the CIR Sand Casting System is that the CIR Casting System uses light-weight, polystyrene beads in place of silica sand as the primary material for casting the negative mold. The formed negative mold can be converted into a positive sand model for modification and socket formation. With the new plaster-less casting system, the prosthetist can fabricate a transtibial prosthesis in about one hour. It reduces the set-up cost, overall weight and size of the casting system, and increases portability for service in remote areas. The System also creates minimal waste and is energy-conserving and environmentally-friendly. PMID:19235060

Wu, Yeongchi; Casanova, Hector R; Reisinger, Kim D; Smith, William K; Childress, Dudley S

2009-03-01

366

Vascular Access Procedures  

Science.gov (United States)

... a needle, a guide wire and a vascular access catheter are used. The equipment typically used for this examination consists of a ... x-ray machine and a detector that is suspended over a table on which the patient lies. The x-ray equipment allows the operator to watch the wire and ...

367

Automated Methods Of Corrosion Measurements  

DEFF Research Database (Denmark)

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.

Bech-Nielsen, Gregers; Andersen, Jens Enevold Thaulov

1997-01-01

368

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

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents the results of examination concerning optimization of the ? phase precipitates with respect to the functional properties of ferritic-austenitic cast steel. The examined material comprised two grades of corrosion-resistant cast steel, namely GX2CrNiMoN25-6-3 and GX2CrNiMoCuN25-6-3-3, used for example in elements of systems of wet flue gas desulphurisation in power industry. The operating conditions in media heated up to 70°C and containing Cl- and SO4 ions and solid particles produce high erosive and corrosive wear. The work proposes an application of the ? phase as a component of precipitation strengthening mechanism in order to increase the functional properties of the material. Morphology and quantities of ? phase precipitates were determined, as well as its influence on the erosion and corrosion wear resistance. It was shown that annealing at 800°C or 900°C significantly improves tribological properties as compared with the supersaturated state, and the best erosion and corrosion wear resistance achieved due to the ferrite decomposition ? ? ?’ + ? was exhibited in the case of annealing at the temperature of 800°C for 3 hours.

Z. Stradomski

2012-04-01

369

[Physiologo-hygienic features of workers engaged in welding cast-iron items with preliminary heating].  

Science.gov (United States)

It was established that in welding of cast-iron wares with their preliminary heating, the thermal factor occupies the leading place in overstrain of the physiological reactions of the worker's body. The workers showed an increase of the average values of most indices of the thermal state and cardio-vascular system. Hygienic measures directed to prevent conveying heat to the working zone of the welder are described. PMID:2711682

Kucheruk, T K; Riazanov, A V

1989-02-01

370

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

International Nuclear Information System (INIS)

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

371

New fibreglass casting system in orthopaedic practice.  

Science.gov (United States)

The composition, manufacture and application of a new fibreglass casting system for use in orthopaedic practice are described. The performance of the first 51 fibreglass casts used in routine fracture work is reviewed. The advantages (the cast is waterprof, extremely light and strong) and the disadvantages (an ultraviolet light source is required to cure the cast and the fiberglass tape is rather expensive) are evaluated. PMID:979766

Davis, B; Dooley, B

1976-06-26

372

Study of pinholes genesis in iron castings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Elbel, T.; Hampl, J.; Senkypl, M.

2011-01-01

373

Developing technological process of obtaining giality casts  

Directory of Open Access Journals (Sweden)

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.

A. Issagulov

2014-10-01

374

Titanium investiment casting defects: A metallographic overview  

Science.gov (United States)

Although titanium castings have been used in aerospace structures for decades, those uses have largely been in secondary applications. Expanding the use of titanium castings in critical applications would be encouraged by a better understanding of investment casting defects in titanium alloy systems. This paper describes several types of casting-related defects that are identified as potentially affecting the design life of a structure: inclusions, voids, and weld repair defects.

Cotton, J. D.; Clark, L. P.; Phelps, H. R.

2006-06-01

375

The heat treatment of Fermanal cast steel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The study discloses the results of microstructural examinations, testing of magnetic properties and hardness measurements as cast and after heat treatment conducted on the Fermanal cast steel. A characteristic feature of this cast steel is its density lower by about 10% than the density of carbon cast steel [4]. It has been proved that the factor deciding about the composition of microstructure (fraction of ferrite and austenite) is the content of aluminium. The matrix totally austenitic is p...

Binczyk, F.; Smolin?ski, A.; Szymszal, J.

2007-01-01

376

ENVIRONMENTAL ASSESSMENT OF IRON CASTING  

Science.gov (United States)

Sampling of ductile iron casting in green sand molds with phenolic isocyanate cores and in phenol-formaldehyde bound shell molds did not provide definitive proof that environmentally hazardous organic emission occur. Both molding systems produced the same type of major emissions,...

377

Cern Axion Solar Telescope (CAST)  

CERN Multimedia

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

2002-01-01

378

The CAST time projection chamber  

Science.gov (United States)

One of the three x-ray detectors of the CERN Axion Solar Telescope (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 set to a safe level 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 × 10-5 counts cm-2 s-1 keV-1 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.

Autiero, D.; Beltrán, B.; Carmona, J. M.; Cebrián, S.; Chesi, E.; Davenport, M.; Delattre, M.; Di Lella, L.; Formenti, F.; Irastorza, I. G.; Gómez, H.; Hasinoff, M.; Lakic, B.; Luzón, G.; Morales, J.; Musa, L.; Ortiz, A.; Placci, A.; Rodrigurez, A.; Ruz, J.; Villar, J. A.; Zioutas, K.

2007-06-01

379

Graphite Formation in Cast Iron  

Science.gov (United States)

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

Stefanescu, D. M.

1985-01-01

380

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

International Nuclear Information System (INIS)

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

 
 
 
 
381

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

Energy Technology Data Exchange (ETDEWEB)

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

Rehn, I.M.

1987-05-01

382

High quality steel casting for energy technics  

International Nuclear Information System (INIS)

The casting of several chromium-molybdenum steels for steam and hydraulic turbines is discussed. Non-destructive testing of the castings is performed demonstrating the safety for use in nuclear technology. The effect of metallurgical parameters on steel casting quality, the heat treatment, and the effect of construction design on costs for fettling and repair weldings are considered. (Auth.)

383

Prediction of Microporosity in Shrouded Impeller Castings  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this Cooperative Research and Development Agreement (CRADA) between the Oak Ridge National Laboratory (ORNL) and Morris Bean and Company was to link computer models of heat and fluid flow with previously developed quality criteria for the prediction of microporosity in a Al-4.5% Cu alloy shrouded impeller casting. The results may be used to analyze the casting process design for the commercial production of 206 o alloy shrouded impeller castings. Test impeller castings were poured in the laboratory for the purpose of obtaining thermal data and porosity distributions. Also, a simulation of the test impeller casting was conducted and the results validated with porosity measurements on the test castings. A comparison of the predicted and measured microporosity distributions indicated an excellent correlation between experiments and prediction. The results of the experimental and modeling studies undertaken in this project indicate that the quality criteria developed for the prediction of microporosity in Al-4.5% Cu alloy castings can accurately predict regions of elevated microporosity even in complex castings such as the shrouded impeller casting. Accordingly, it should be possible to use quality criteria for porosity prediction in conjunction with computer models of heat and fluid flow to optimize the casting process for the production of shrouded impeller castings. Since high levels of microporosity may be expected to result in poor fatigue properties, casting designs that are optimized for low levels of microporosity should exhibit superior fatigue life.

Viswanathan, S. Nelson, C.D.

1998-09-01

384

Aluminum Corrosion and Turbidity  

International Nuclear Information System (INIS)

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

385

Archaeological analogs and corrosion  

International Nuclear Information System (INIS)

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

386

Corrosion evaluation technology  

International Nuclear Information System (INIS)

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