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1

Vascular corrosion casting of human heart  

Directory of Open Access Journals (Sweden)

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

J. Vasudeva Reddy; S. Lokanadham

2013-01-01

2

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

UK PubMed Central (United Kingdom)

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

Cotrufo S; Dabernig J; Russell D; Payne A; Hart A

2010-01-01

3

To study the intrarenal vascular segments of human kidney by corrosion cast technique.  

UK PubMed Central (United Kingdom)

A study of the intrarenal arterial pattern of kidney by corrosion cast method has been carried out on 100 kidneys obtained from post mortem bodies. The abnormal origin of renal artery is rare and observed only in 2% cases. The renal artery divides extrarenally in about 68%, intrarenally in about 18% and at the hilum in 14% cases into anterior and posterior divisions. In very rare cases (2%) both the divisions arise separately at one point from abdominal aorta. Alternatively renal artery may not divide into anterior and posterior divisions but continues as anterior division and divide into upper, middle and lower segmental arteries in 1% cases. The branching pattern of anterior division shows 5 different variations grouped in 5 groups. The branching pattern of posterior division shows 3 different patterns. Vary rarely (1%) the posterior division is absent. Origin of apical segmental artery shows many variations and are grouped into 7 types. Origin and intrarenal branching pattern of upper, middle and lower segmental arteries shows many variations. Presence of accessory renal artery is a rare occurrence (about 2%). As there is no constant arterial segmental patterns of the kidney, it may often not be possible to forecast beforehand the type of partial nephrectomy which might or might not be possible in a particular case. Hence, for practical purposes, attempts at grouping and classification of variable arterial pattern seen is hardly of much significance. Very often, the decision to perform a segmental resection of the kidney shall have to be taken on operation table by surgeon after exploration of kidney or before operation by angiography. But it may of importance for surgeon to be acquainted with different types of cases unsuitable for segmental resection and this will put the surgeon on guad to exercise greater cautions.

Ajmani ML; Ajmani K

1983-01-01

4

3D analysis of SEM images of corrosion casting using adaptive stereo matching.  

UK PubMed Central (United Kingdom)

The corrosion casting method represents one of the most widely used technique to study the 3D microvascularization of many tissues, both in their normal and pathological conditions. For a long time this technique was used only to perform a qualitative evaluation of the images obtained by scanning electron microscopy (SEM). A quantitative evaluation of vascular parameters (e.g., interbranching and intervascular distances, angle measurements, lengths and diameters) was lacking, mainly because of the difficulties found in the measurement performed on 2D SEM images. Then, some authors reported a quantitative method based on the analyses of stereo-pair images that allowed precise morphometric measurements. To visualize the specimens in 3D, it was necessary to use red-green glasses. In this article we describe a new approach by which we can automatically obtain a 3D reconstruction of vascular cast specimen's surface directly from stereo-images. Moreover, we developed a software that performed micrometric measurements on the 3D construct generated from the stereo-pictures. In conclusion, implementing together these two softwares and applying them to corrosion casting samples made it possible to render in 3D the surface of corrosion cast as well as make quantitative measurements on the corrosion casts.

Manelli A; Sangiorgi S; Binaghi E; Raspanti M

2007-04-01

5

3D analysis of SEM images of corrosion casting using adaptive stereo matching.  

Science.gov (United States)

The corrosion casting method represents one of the most widely used technique to study the 3D microvascularization of many tissues, both in their normal and pathological conditions. For a long time this technique was used only to perform a qualitative evaluation of the images obtained by scanning electron microscopy (SEM). A quantitative evaluation of vascular parameters (e.g., interbranching and intervascular distances, angle measurements, lengths and diameters) was lacking, mainly because of the difficulties found in the measurement performed on 2D SEM images. Then, some authors reported a quantitative method based on the analyses of stereo-pair images that allowed precise morphometric measurements. To visualize the specimens in 3D, it was necessary to use red-green glasses. In this article we describe a new approach by which we can automatically obtain a 3D reconstruction of vascular cast specimen's surface directly from stereo-images. Moreover, we developed a software that performed micrometric measurements on the 3D construct generated from the stereo-pictures. In conclusion, implementing together these two softwares and applying them to corrosion casting samples made it possible to render in 3D the surface of corrosion cast as well as make quantitative measurements on the corrosion casts. PMID:17262784

Manelli, A; Sangiorgi, S; Binaghi, E; Raspanti, M

2007-04-01

6

Evaluation of Accelerated Graphitic Corrosion Test of Gray Cast Iron  

International Nuclear Information System (INIS)

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

2011-01-01

7

The chloride corrosion of low-gold casting alloys.  

Science.gov (United States)

Potentiodynamic polarization measurements have indicated that the so-called 'low-gold' casting alloys are characterized by decreased chloride corrosion resistance, when compared with ADA Type III and Type IV gold alloys. This decrease in chloride corrosion resistance results apparently from the presence of Ag-rich microsegregations with a possible minor contribution from Cu-rich segregations or precipitates. PMID:283085

Sarkar, N K; Fuys, R A; Stanford, J W

1979-02-01

8

The chloride corrosion of low-gold casting alloys.  

UK PubMed Central (United Kingdom)

Potentiodynamic polarization measurements have indicated that the so-called 'low-gold' casting alloys are characterized by decreased chloride corrosion resistance, when compared with ADA Type III and Type IV gold alloys. This decrease in chloride corrosion resistance results apparently from the presence of Ag-rich microsegregations with a possible minor contribution from Cu-rich segregations or precipitates.

Sarkar NK; Fuys RA Jr; Stanford JW

1979-02-01

9

Chemical corrosion in cast iron in soil-water medium.  

UK PubMed Central (United Kingdom)

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

Mukesh K; Panday YD

2001-02-01

10

Corrosion resistant gray cast iron graphite flake alloys  

Energy Technology Data Exchange (ETDEWEB)

Corrosion resistant gray cast iron alloys useful in downhole oil well environments and the like. The alloys are substantially lower in cost and substantially higher in tensile strength than high nickel-copper cast irons commonly used downhole in submergible pumps. The alloys contain substantial amounts of aluminum in combination with nickel, chromium, manganese, molybdenum, carbon, silicon, and iron. Copper, tin, vanadium, and boron may also be included. Both hardenable and non-hardenable alloys are provided.

Betts, B. A.

1985-10-22

11

Localized corrosion of aluminium based cast composites in marine environments  

Energy Technology Data Exchange (ETDEWEB)

Localized corrosion of metal matrix composites in marine environments poses a serious concern to the structural integrity of components made of aluminum based composites. Studies on cast composites of aluminum alloys reinforced with different volume percent of SiC particles of different sizes indicated the enhanced susceptibility of composites to localized corrosion like pitting and crevice corrosion. Aging treatments were performed to enhance the resistance to pitting and crevice attack. These studies were performed to choose the electrochemical technique which provides the maximum information about the mechanism of attack with best sensitivity of detection.

Rawat, A.K.; Desai, V.H. [Univ. of Central Florida, Orlando, FL (United States)

1995-11-01

12

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-02-01

13

Corrosion resistant high silicon cast iron  

International Nuclear Information System (INIS)

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

2003-01-01

14

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

15

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

Directory of Open Access Journals (Sweden)

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

LI Wei; LIU Jun-quan; TU Xiao-hui3

2007-01-01

16

Role of alloy matrix and dispersoid on corrosion behavior of cast aluminum alloy composites  

Energy Technology Data Exchange (ETDEWEB)

Observations made during the corrosion of cast aluminum alloys dispersed with graphite/silicon carbide (SiC) particles were analyzed. Corrosion studies were carried out in 3 wt% sodium chloride (NaCl) solution using salt immersion and potentiodynamic techniques. Corresponding base alloys were subjected to identical test conditions to understand the influence of the dispersoid on corrosion behavior. In all cases, the composites exhibited higher corrosion loss over the respective matrix alloy. Weight loss increased with exposure time. The dispersoid/matrix and the precipitate/matrix interfaces were found to be favorable sites for nucleation of corrosion pits. Results were explained with the help of microstructural observations and electrochemical parameters.

Modi, O.P.; Saxena, M.; Prasad, B.K.; Jha, A.K.; Das, S.; Yegneswaran, A.H. [Regional Research Lab., Bhopal (India)

1998-02-01

17

Corrosion Mechanisms of Steel and Cast Iron by Molten Aluminum  

Science.gov (United States)

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

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

2010-09-01

18

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

Energy Technology Data Exchange (ETDEWEB)

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

Smart, N.R. [AEA Technology plc, Culham Science Centre (United Kingdom); Blackwood, D.J. [National Univ. of Singapore (Singapore); Werme, L. [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

2001-07-01

19

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

International Nuclear Information System (INIS)

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

2001-01-01

20

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

International Nuclear Information System (INIS)

[en] 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)

1985-01-01

 
 
 
 
21

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

2011-01-01

22

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2006-05-25

23

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

International Nuclear Information System (INIS)

[en] 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

2006-05-25

24

Evaluation of abrasive-wear and erosion-corrosion resistance of high-Cr cast-steel  

Energy Technology Data Exchange (ETDEWEB)

In order to evaluate the performance of high-Cr cast-steel (15.4% Cr), as a pump casing material, abrasive wear, hardness, corrosion, erosion-corrosion resistance were examined and compared with grey cast iron eventually used. The results obtained were analyzed on a microstructural basis with respect to Cr content of the matrix, amount and types of carbides and the extent of surface passivation. Martensitic high-Cr steel has shown a better performance than grey cast iron. (orig.)

Metwally, W.A. (Steel Alloys Dept., Central Metallurgical Research and Development Inst. (CMRDI), Cairo (Egypt)); Samy, M.K. (Steel Alloys Dept., Central Metallurgical Research and Development Inst. (CMRDI), Cairo (Egypt))

1994-10-01

25

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

International Nuclear Information System (INIS)

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

2009-01-01

26

Effect of Corrosion Resistant Coatings on the Fatigue Strength of Cast Magnesium Alloys.  

Science.gov (United States)

A study was made for the Army Aviation Materiel Readiness Command to evaluate the effects of various surface treatments and corrosion resistant coating systems on the fatigue properties of three send cast magnesium alloys (AZ91-T6, ZE41-T5, and EZ33-T5) o...

J. J. Bethke

1977-01-01

27

Effect of tempering on corrosion resistance of cast aluminium bronzes  

International Nuclear Information System (INIS)

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

1985-01-01

28

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

International Nuclear Information System (INIS)

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

1991-01-01

29

Corrosive wear of cast iron in oil-sulphuric acid mixtures  

Energy Technology Data Exchange (ETDEWEB)

A study has been undertaken into the corrosive wear of marine diesel engine piston ring cast iron pin specimens against cylinder lining grey cast iron disc specimens during reciprocating sliding in mixtures of base lubricating oil and 10% sulphuric acid solution. Wear is low in the base-oil environment. The presence of 5% or 10% acid in the oil is sufficient to disrupt partially the hydrodynamic oil film, giving significant periods of metal-metal contact. The dispersed nature of the acid droplets in the oil restricts corrosion to localized sites on the metal surfaces and wear damage is mainly due to mechanical processes. As the volume of acid in oil is increased to 20% and 40%, the hydrodynamic oil film is disrupted almost completely and the aqueous phase becomes almost continuous. This increases the contribution of electrochemical corrosion to the corrosive wear phenomenon as the products of corrosion are removed rapidly from the contacting surfaces by the sliding action. In this situation, both corrosive and mechanical processes contribute to the overall wear damage.

Macdonald, A.G.; Stott, F.H.

1988-01-01

30

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

31

Corrosion resistance of As-cast cu-Mo added pearlitic ductile cast iron. Cu Mo tenka ibanashi pearlite kei kyujo kokuen chutetsu no taishokusei  

Energy Technology Data Exchange (ETDEWEB)

A series of studies is being performed that is intended to establish techniques to manufacture spherical graphite having pearlitic bases. This paper discusses its corrosion resistance to cooling water (tap water) said to be inferior to ferrite-based spherical graphite and carbon steel cast iron. The test pieces were as-cast pearlitic iron, cast especially with materials added with Cu and Mo. The corrosion resistance was discussed by performing immersion and rotating bending tests using a nitrite-based rust inhibitor. The result may be summarized as follows: The corrosion resistance of as-cast pearlitic spherical graphite cast iron shows a trend of being slightly more sensitive to interfering ions of the rust inhibitor than carbon steel cast iron; however, under a condition of the empirically known maximum concentration of interfering ions contained in cooling water, that is sulfuric acid ion at 50 ppm and chlorine ion at 100 ppm, adding the rust inhibitor at 6000 ppm restores the corrosion fatigue strength to that in the atmosphere, and have it exceed that for the carbon steel cast iron at the same time. 9 refs., 9 figs., 7 tabs.

Yamamoto, S.; Ono, S.; Fukuda, M. (Mitsubishi Heavy Industries, Ltd., Tokyo (Japan))

1993-09-25

32

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

33

In vitro corrosion of dental Au-based casting alloys in polyvinylpyrrolidone-iodine solution.  

UK PubMed Central (United Kingdom)

The corrosion and tarnish behaviors of two Au-based casting alloys (ISO type 1 and type 4 Au alloys) and their constituent pure metals, Au, Ag, Cu, Pt, and Pd in a polyvinylpyrrolidone-iodine solution were examined. The two Au alloys actively corroded, and the main anodic reaction for both was dissolution of Au as AuI?(-). The amount of Au released from the ISO type 1 Au alloy was significantly larger than that from the ISO type 4 Au alloy (P<0.05). Visible light spectrophotometry revealed that the type 1 alloy exhibited higher susceptibility to tarnishing than the type 4 alloy. The corrosion forms of the two Au alloys were found to be completely different, i.e., the type 1 alloy exhibited the corrosion attack over the entire exposed surface with a little irregularity whereas the type 4 alloy exhibited typical intergranular corrosion, which was caused by local cells produced by segregation of Pd and Pt.

Takasusuki N; Ida Y; Hirose Y; Ochi M; Endo K

2013-01-01

34

Corrosion of copper, nickel, and gold dental casting alloys: an in vitro and in vivo study.  

UK PubMed Central (United Kingdom)

The corrosion behavior of commercially available copper, nickel, and gold alloys for dental castings was investigated. The alloys investigated included: three copper alloys (76-87Cu, 6-11A1, 0-12Zn, 1-5Ni, 0-4Fe, 0.5-1.2Mn), two nickel alloys (68-78Ni, 12-16Cr, 4-14Mo, 0-1.7Be), and one gold alloy (77Au, 14Ag, 8Cu, 1Pd). Anodic and cathodic polarization curves, long-term immersion tests in saline and artificial saliva solutions, and dog crown studies were conducted to evaluate both the in vitro and in vivo corrosion characteristics of the alloys. All evaluations conducted demonstrated that the copper alloys were highly susceptible to corrosion attack. High corrosion currents were observed in the in vitro tests, and SEM of the alloys specimens showed significantly altered surfaces. The anodic polarization curves predicted that the beryllium-containing nickel alloy should be susceptible to localized corrosion and SEM revealed an etched surface with corrosion of certain microstructural features. No significant corrosion was predicted or observed for the non-beryllium nickel alloy and the gold alloy. The in vitro corrosion evaluations predicted the in vivo corrosion behavior for the alloys. Since the three copper alloys and the beryllium-containing nickel alloy demonstrated significant corrosion under the tested conditions, the use of these alloys for restorative procedures is questionable due to the release of significant levels of selected ions to the oral cavity.

Johansson BI; Lucas LC; Lemons JE

1989-12-01

35

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

UK PubMed Central (United Kingdom)

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.

Rajeswari V; Kesavan D; Gopiraman M; Viswanathamurthi P

2013-06-01

36

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

2012-01-01

37

In vitro corrosion behavior of cast iron-platinum magnetic alloys.  

UK PubMed Central (United Kingdom)

OBJECTIVE: The objective of this study was to investigate the corrosion resistance of cast Fe-Pt alloys of varying compositions for use as attachment keepers and to make a comparison with the corrosion resistance of magnetic stainless steel. METHODS: The corrosion behavior of cast Fe-Pt alloy keepers (Fe-40 at%Pt, Fe-38 at%Pt, Fe-37 at%Pt and Fe-36 at%Pt) was evaluated by means of an immersion test and an anodic polarization test. The solutions used were a 1.0% lactic acid aqueous solution (pH=2.3) (10 ml) and 0.9% NaCl solution (pH=7.3) (10 ml). As a control, the corrosion resistance of a magnetic stainless steel keeper (SUS 447J1: HICOREX) was also measured. RESULTS: Chromium and platinum ions were not detected in either the 1.0% lactic acid or 0.9% NaCl solutions. The only released ions detected were the Fe ions in the 1.0% lactic acid solution. The amounts of Fe ions released from the Fe-40 at%Pt and Fe-38 at%Pt alloys were significantly (p<0.05) lower than from the Fe-37at%Pt, Fe-36 at%Pt and SUS 447J1 alloys. In the anodic polarization test, the potentials at the beginning of passivation for the four Fe-Pt alloys were higher than for the SUS 447J1 alloy in both solutions. SIGNIFICANCE: The Fe-Pt alloys, especially the alloys with higher Pt percentages (Fe-40 and 38 at%Pt), indicated a high corrosion resistance compared to the magnetic stainless steel keeper. A reduction in the Pt percentage may decrease the corrosion resistance in the oral environment.

Watanabe I; Hai K; Tanaka Y; Hisatsune K; Atsuta M

2001-05-01

38

The chorioallantoic capillary plexus of the chicken egg: a microvascular corrosion casting study.  

UK PubMed Central (United Kingdom)

The chorioallantoic membrane of the avian egg serves as the principal organ of respiratory gaseous exchange for the embryo until close to hatching. It lies closely apposed to the inner shell membrane and contains an extremely dense capillary plexus supplied by the allantoic blood vessels. This study applied the microvascular corrosion casting technique to investigate the three-dimensional arrangement of the plexus at various stages of incubation. Casts were produced between days 6 and 14 of incubation, and their appearances were compared with those obtained from traditionally sectioned material and from freeze-cleaved specimens. By day 6 the capillary network was remarkably profuse but showed considerable regional variation in vessel density. In some areas there were only short capillary buds whereas in other areas fusion had taken place so that a true plexus was formed. By day 10 the capillaries had become confluent to such a degree that the cast consisted of a thin sheet of resin perforated only by an array of small irregularly shaped orifices. These corresponded closely in size to the intervening columns of chorionic epithelial cells seen in the sectioned material. It is clear from the appearances of the casts that the capillary surface density becomes maximal at approximately day 10 of incubation. From then on in incubation any increase in the diffusing capacity of the chorioallantoic membrane must be the result of either an increase in its overall surface area, or a decrease in the thickness of the air-blood barrier.

Burton GJ; Palmer ME

1989-06-01

39

Behaviour of alloyed white cast-iron in a corrosive environment; Comportement des fontes blanches alliees dans les milieux corrosifs  

Energy Technology Data Exchange (ETDEWEB)

In this work the effect of the composition of white cast-iron on its corrosion resistance was evaluated by investigating the behaviour of the white cast-iron alloyed with chromium, chromium-manganese and chromium-manganese-vanadium and niobium in corrosive environment. The positive influence of Cr, Mn, Nb et V was evidenced. The effect of chromium on the corrosion resistance is linked to the quantity and the type of carbides that are formed within the cast iron and thus depends on its carbon content. The action of manganese is linked to its distribution between the carbides and the metallic matrix. By partially substituting Fe and chromium, it improves the corrosion resistance. The introduction of elements with a strong affinity towards carbon such as vanadium and niobium shifts the anodic curves to the side of the weak corrosion current. These elements induce a double effect: the improvement of the corrosion resistance and the structure refinement for a weak content of these elements. The studied alloyed white cast-iron are used in particular in the petroleum industry (Algeria). (authors)

Hadji, A.; Lemmout, A. [Universite d' Annaba, El Hadjar Annaba (Algeria); Romanov, L.M.; Kozlov, L.Y. [Institut de l' Acier et des Alliage, Moscou (Russian Federation)

2000-06-01

40

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

International Nuclear Information System (INIS)

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

2004-01-01

 
 
 
 
41

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

Energy Technology Data Exchange (ETDEWEB)

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

Sadiq, Rehan; Rajani, Balvant; Kleiner, Yehuda

2004-10-01

42

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-06-15

43

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

International Nuclear Information System (INIS)

[en] 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.

2010-01-01

44

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

UK PubMed Central (United Kingdom)

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

Wang H; Hu C; Hu X; Yang M; Qu J

2012-03-01

45

Corrosion behavior of cast titanium with reduced surface reaction layer made by a face-coating method.  

Science.gov (United States)

This study characterized the corrosion behavior of cast CP titanium made with a face-coating method. Wax patterns were coated with oxide slurry of Y(2)O(3) or ZrO(2) before investing with a MgO-based investment. Three surface preparations were tested: ground, sandblasted, and as-cast. Uncoated castings served as controls. Sixteen-hour open circuit potential (OCP) measurement, linear polarization and potentiodynamic cathodic polarization were performed in an aerated modified Tani-Zucchi synthetic saliva at 37 degrees C. Anodic polarization was conducted in the same deaerated medium. Polarization resistance (R(p)) and Tafel slopes were determined. Corrosion current density was calculated for each specimen. Results (n=4) were subjected to nonparametric statistical analysis (alpha=0.05). Cross sections of cast specimens were examined by optical microscopy. Energy dispersive spectroscopy (EDS) spot analysis was performed at various depths below the surface. The OCP stabilized within several hours for all the specimens. Apparent differences in anodic polarization behavior were observed among the different surfaces. A distinctive wide passive region followed by breakdown was seen on specimens with ground and sandblasted surfaces. There were no significant differences in the corrosion resistance among the control and the two face-coating groups for each group. The Mann-Whitney test showed significantly lower OCP and higher R(p) values for ground surfaces. The surface condition significantly affected the corrosion behavior more than the face coating methods. In most cases, specimens with as-cast surfaces exhibited the least corrosion resistance during the potentiodynamic anodic polarization. PMID:12950996

Koike, M; Cai, Z; Fujii, H; Brezner, M; Okabe, T

2003-11-01

46

Corrosion behavior of cast titanium with reduced surface reaction layer made by a face-coating method.  

UK PubMed Central (United Kingdom)

This study characterized the corrosion behavior of cast CP titanium made with a face-coating method. Wax patterns were coated with oxide slurry of Y(2)O(3) or ZrO(2) before investing with a MgO-based investment. Three surface preparations were tested: ground, sandblasted, and as-cast. Uncoated castings served as controls. Sixteen-hour open circuit potential (OCP) measurement, linear polarization and potentiodynamic cathodic polarization were performed in an aerated modified Tani-Zucchi synthetic saliva at 37 degrees C. Anodic polarization was conducted in the same deaerated medium. Polarization resistance (R(p)) and Tafel slopes were determined. Corrosion current density was calculated for each specimen. Results (n=4) were subjected to nonparametric statistical analysis (alpha=0.05). Cross sections of cast specimens were examined by optical microscopy. Energy dispersive spectroscopy (EDS) spot analysis was performed at various depths below the surface. The OCP stabilized within several hours for all the specimens. Apparent differences in anodic polarization behavior were observed among the different surfaces. A distinctive wide passive region followed by breakdown was seen on specimens with ground and sandblasted surfaces. There were no significant differences in the corrosion resistance among the control and the two face-coating groups for each group. The Mann-Whitney test showed significantly lower OCP and higher R(p) values for ground surfaces. The surface condition significantly affected the corrosion behavior more than the face coating methods. In most cases, specimens with as-cast surfaces exhibited the least corrosion resistance during the potentiodynamic anodic polarization.

Koike M; Cai Z; Fujii H; Brezner M; Okabe T

2003-11-01

47

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

International Nuclear Information System (INIS)

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

2002-01-01

48

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

Energy Technology Data Exchange (ETDEWEB)

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

Yamada, T.; Totsuka, N.; Nakajima, N.; Arioka, K. [Institute of Nuclear Safety System, Inc., Mikata-gun, Fukui (Japan); Negishi, K. [Aomori Gennen Technology Center, Touhoku-cho, Kamikita-gun, Aomori (Japan)

2002-07-01

49

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

50

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

1981-01-01

51

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

Directory of Open Access Journals (Sweden)

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

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

2009-01-01

52

[Corrosion property and oxide film of dental casting alloys before and after porcelain firing].  

UK PubMed Central (United Kingdom)

OBJECTIVE: To evaluate the types and compositions of oxide films formed during porcelain-fused-to-metal (PFM) firing on three kinds of dental casting alloys, and to investigate the corrosion property of these alloys in Dulbecco's modification of Eagle's medium (DMEM) cell culture fluid, before and after PFM firing. METHODS: Specimens of three dental casting alloys (Ni-Cr, Co-Cr and Ni-Ti) before and after PFM firing were prepared, and were immersed in DMEM cell culture fluid. After 30 days, the type and concentration of released metal ions were measured using inductively coupled plasma atomic emission spectroscopy (ICP-AES). X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used for analysis of oxide film on the alloys. One way-ANOVA was adopted in data analysis. RESULTS: The total amount of metal ions released from the three dental alloys was found to be highest in Ni-Cr alloy [(2.829 ± 0.694) mg/L], followed by Co-Cr [(2.120 ± 0.418) mg/L] and Ni-Ti alloy [(1.211 ± 0.101) mg/L]. The amount of Ni ions released from Ni-Cr alloys [(1.531 ± 0.392) mg/L] was higher than that from Ni-Ti alloys [(0.830 ± 0.052) mg/L]. The amount of Cr, Mo ions released from Co-Cr alloy [Cr: (0.048 ± 0.011) mg/L, Mo: (1.562 ± 0.333) mg/L] was higher than that from Ni-Cr alloy [Cr: (0.034 ± 0.002) mg/L, Mo: (1.264 ± 0.302) mg/L] and Ni-Ti alloy [Cr: (0.013 ± 0.006) mg/L, Mo: (0.151 ± 0.026) mg/L] (P < 0.05). After PFM firing, the total amount of metal irons released from the three dental alloys decreased [Ni-Cr: (0.861 ± 0.054) mg/L, Co-Cr: (0.695 ± 0.327) mg/L, Ni-Ti: (0.892 ± 0.115) mg/L] (P < 0.05). In addition, XPS showed increase of Cr(2)O(3) and Mo-Ni oxide on the surface of all the alloys after PFM firing. CONCLUSIONS: The amount of ions released from Ni-Cr alloy was the highest among the three dental casting alloys, this means Ni-Cr alloy is prone to corrode. The PFM firing process changed the alloys' surface composition. Increased Ni, Cr and Mo were found in oxide film, and the increase in Cr(2)O(3) can improve the corrosion-resistance of alloys.

Ma Q; Wu FM

2011-03-01

53

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-07-01

54

Improvement of corrosion resistance of cast iron by laser surface melting; Laser hyomen yoyu shori ni yoru chutetsu no taishokusei no kaizen  

Energy Technology Data Exchange (ETDEWEB)

Laser surface melting (LSM) treatment using continuous wave CO2 laser was applied for improvement of general corrosion of nodular graphite cast iron and grey cast iron. Corrosion behavior of as-melted` surface and reheated surface were evaluated by immersion and potentiodynamic tests. A chill surface layer was formed due to rapid solidification in applying LSM treatment, and corrosion rate in 0.05 kmol/m{sup 3}-H2SO4 solution decreased except heat affected zone. By LSM treatment, current density decreased in passive range in anodic polarization curves, which coincided with immersion test. This improvement of corrosion resistance by LSM treatment is caused by the disappearance of graphite due to rapid solidification. Resistance to general corrosion of LSM specimen was maintained by reheating treatment, which coincided with anodic polarization curves. 8 refs., 12 figs., 1 tab.

Osawa, M. [Tokyo Denki University, Tokyo (Japan)

1996-01-15

55

The uterine vascular system of the golden hamster and its changes during the oestrous cycle.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The vascular pattern of the hamster uterus and its changes during the oestrous cycle were studied by using the corrosion vascular casting method. The vascular system of the hamster uterus has two main division, the circumferential division and the medial arterial division. The former consists of cir...

Ogura, A; Nishida, T

56

Influence of microstructure on corrosion of as-cast ZE41  

Energy Technology Data Exchange (ETDEWEB)

Corrosion of ZE41 initiated in the {alpha}-Mg matrix adjacent to the eutectic micro-constituent and was attributed to micro-galvanic corrosion of the {alpha}-Mg matrix coupled to the eutectic micro-constituent. The eutectic micro-constituent did not act as a corrosion barrier and did not stop the advance of the corrosion. As a consequence, the {alpha}-Mg matrix corroded over the whole surface with little corrosion of the inter-connected eutectic micro-constituent. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

Zhao, M.C.; Liu, M. [Division of Materials, The University of Queensland, Brisbane, Qld 4072 (Australia); Swiss Federal Laboratories for Materials Science and Technology, EMPA, Dept 136, Ueberlandstrasse 129, CH-8600 Dubendorf (Switzerland); Song, G.L. [Division of Materials, The University of Queensland, Brisbane, Qld 4072 (Australia); Atrens, A.

2008-02-15

57

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

Science.gov (United States)

The novel interpenetrating (HA+?-TCP)/MgCa composites were fabricated by infiltrating MgCa alloy into porous HA+?-TCP using suction casting technique. The microstructure, mechanical properties and corrosion behaviors of the composites have been evaluated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical testing, electrochemical and immersion tests. It was shown that the composites had compact structure and the interfacial bonding between MgCa alloy and HA+?-TCP scaffolds was very well. The ultimate compressive strength of the composites was about 500-1000 fold higher than that of the original porous scaffolds, and it still retained quarter-half of the strength of the bulk MgCa alloy. The electrochemical and immersion tests indicated that the corrosion resistance of the composites was better than that of the MgCa matrix alloy, and the corrosion products of the composite surface were mainly Mg(OH)2, HA and Ca3(PO4)2. Meanwhile, the mechanical and corrosive properties of the (HA+?-TCP)/MgCa composites were adjustable by the choice of HA content. PMID:23910342

Wang, X; Dong, L H; Li, J T; Li, X L; Ma, X L; Zheng, Y F

2013-06-26

58

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

International Nuclear Information System (INIS)

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

1989-01-01

59

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

UK PubMed Central (United Kingdom)

The microvascular bed of the stomach of Xenopus laevis and the changes it undergoes when the herbivorous tadpole becomes a carnivorous adult were studied by scanning electron microscopy of vascular corrosion casts and light microscopy of stained tissue sections. In tadpoles an upper and a lower gastric artery supplied, and upper, middle and lower medial and lateral gastric veins drained the vertically extending stomach. During metamorphosis, the stomach gained a horizontal cranio-caudal extension and vessels accordingly become dorsal and ventral gastric arteries, and anterior, middle and posterior gastric veins, respectively. Up to stage 64 (late climax) mucosal capillaries formed a polygonal network of wide immature-looking capillaries ensheathing gastric glands in a basket-like manner. From stage 64 onwards, blood vessels of the stomach appeared mature, revealed a clear hierarchy and were correlated closely with the histomorphology of the stomach, which had also gained the adult pattern. Within the gastric mucosa, ascending arterioles branched in a fountain-like pattern into wide subepithelial capillaries establishing a centripetal blood flow along the gastric glands, which makes an ultrashort control loop of glandular cells within the branched tubular gastric glands very unlikely. Formation of the stomach external muscular layer started at stage 57 when smooth muscle cells locally formed a single longitudinal and one-to-two single circular layers. Abundant signs of intussusceptive microvascular growth and rare vascular sprouts in vascular corrosion casts indicated that the larval-to-adult microvascular pattern formation of the stomach of Xenopus laevis Daudin occurs predominantly by non-sprouting angiogenesis.

Lametschwandtner A; Höll M; Bartel H; Anupunpisit V; Minnich B

2012-06-01

60

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

Science.gov (United States)

The microvascular bed of the stomach of Xenopus laevis and the changes it undergoes when the herbivorous tadpole becomes a carnivorous adult were studied by scanning electron microscopy of vascular corrosion casts and light microscopy of stained tissue sections. In tadpoles an upper and a lower gastric artery supplied, and upper, middle and lower medial and lateral gastric veins drained the vertically extending stomach. During metamorphosis, the stomach gained a horizontal cranio-caudal extension and vessels accordingly become dorsal and ventral gastric arteries, and anterior, middle and posterior gastric veins, respectively. Up to stage 64 (late climax) mucosal capillaries formed a polygonal network of wide immature-looking capillaries ensheathing gastric glands in a basket-like manner. From stage 64 onwards, blood vessels of the stomach appeared mature, revealed a clear hierarchy and were correlated closely with the histomorphology of the stomach, which had also gained the adult pattern. Within the gastric mucosa, ascending arterioles branched in a fountain-like pattern into wide subepithelial capillaries establishing a centripetal blood flow along the gastric glands, which makes an ultrashort control loop of glandular cells within the branched tubular gastric glands very unlikely. Formation of the stomach external muscular layer started at stage 57 when smooth muscle cells locally formed a single longitudinal and one-to-two single circular layers. Abundant signs of intussusceptive microvascular growth and rare vascular sprouts in vascular corrosion casts indicated that the larval-to-adult microvascular pattern formation of the stomach of Xenopus laevis Daudin occurs predominantly by non-sprouting angiogenesis. PMID:22237922

Lametschwandtner, Alois; Höll, Monika; Bartel, Heidi; Anupunpisit, Vipavee; Minnich, Bernd

2012-01-12

 
 
 
 
61

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

International Nuclear Information System (INIS)

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

2004-01-01

62

The effect of porous coating processing on the corrosion behavior of cast Co-Cr-Mo surgical implant alloys.  

UK PubMed Central (United Kingdom)

The manufacture of porous coated cobalt-based surgical implant alloys requires sintering--a high temperature process above the incipient melting temperature of this alloy system. The metallurgical changes produced by the high temperature sinter cycle consist of dissolution of interdendritic carbides, massive precipitation of lamellar carbide eutectic phases at grain boundaries, localized porosity from incipient melting that is not completely eliminated by subsequent hot isostatic pressing, and grain growth in fine-grained materials. These microstructural changes, which are known to affect the mechanical properties, do not affect the static in vitro localized and generalized corrosion behavior of the bulk material as determined by anodic polarization measurements in a buffered saline environment and direct examination by scanning electron and optical microscopy. Additionally, cast Co-Cr-Mo surgical implant alloys are found to be immune to crevice corrosion (in the absence of mechanical fretting) in the saline environment studied. The hysteretic component of the anodic polarization curve is not due to crevice corrosion; rather, as suggested by the electrochemical tests and Auger spectroscopy, the hysteresis is due to redox reactions in the chromium-rich surface layer.

Jacobs JJ; Latanision RM; Rose RM; Veeck SJ

1990-11-01

63

Corrosion resistance of TiN and MoN coated grey cast iron in acid solutions  

Energy Technology Data Exchange (ETDEWEB)

Grey cast iron containing 3.39% C, 2.76% Si, 0.37% Mn, 0.05% P and 0.008% S, with different shape of graphite was covered with Mo and Ti nitrides by cathodic are plasma deposition method at 400 C. Incorporation of C from the substrate caused the formation of molybdenum carbide. Formation of diffused interphase layer due to incorporation of Mo into the substrate caused increase in the coating adhesion. Electrochemical measurements showed that H{sub 3}PO{sub 4} and H{sub 2}SO{sub 4} solutions penetrated to substrate through flaws in coatings, mainly occurred at the graphite particles. The local corrosion degradation of material was accompanied by hydrogen evolution and formation of microcracks. In the case of coated vermicular cast iron merging of microcracks led to falling off the pieces of coated material. The Mo containing coatings exhibited lower susceptibility to crack formation but higher susceptibility to environmental degradation than the Ti containing coatings. The highest protection in acid solutions provided the complex (Mo,Ti)N coating. (orig.)

Lunarska, E. [Polish Academy of Sciences, Warsaw (Poland). Inst. of Physical Chemistry

1997-02-01

64

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-11-15

65

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1996-03-25

66

Erosion and corrosion resistant cast iron alloy containing chromium, nickel and molybdenum  

Energy Technology Data Exchange (ETDEWEB)

Cast iron alloy preferably of about 1.6 carbon, 2 nickel, 2 molybdenum, 28 chromium, and up to 1 of an additional element, balance substantially iron characterized by a matrix substantially entirely of tempered martensite with minimal retained austenite, containing ferrite phases and primary chromium-rich carbides with substantially no secondary carbides.

Khandos, I. Y.; Larson, H. R.

1985-08-20

67

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)

[en] 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)

2011-01-01

68

Maximizing modern distribution of complex anatomical spatial information: 3D reconstruction and rapid prototype production of anatomical corrosion casts of human specimens.  

UK PubMed Central (United Kingdom)

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 spatial information were explored to overcome these limitations through the digitalization of anatomical casts of human specimens through three-dimensional (3D) reconstruction, rapid prototype production, and Web-based 3D atlas construction. The corrosion cast of a lung, along with its associated arteries, veins, trachea, and bronchial tree was CT-scanned, and the data was then processed by Mimics software. Data from the lung casts were then reconstructed into 3D models using a hybrid method, utilizing both "image threshold" and "region growing." The fine structures of the bronchial tree, arterial, and venous network of the lung were clearly displayed and demonstrated their distinct relationships. The multiple divisions of bronchi and bronchopulmonary segments were identified. The 3D models were then uploaded into a rapid prototype 3D printer to physically duplicate the cast. The physically duplicated model of the lung was rescanned by CT and reconstructed to detect its production accuracy. Gross observation and accuracy detection were used to evaluate the duplication and few differences were found. Finally, Virtual Reality Modeling Language (VRML) was used to edit the 3D casting models to construct a Web-based 3D atlas accessible through Internet Explorer with 3D display and annotation functions.

Li J; Nie L; Li Z; Lin L; Tang L; Ouyang J

2012-11-01

69

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 spatial information were explored to overcome these limitations through the digitalization of anatomical casts of human specimens through three-dimensional (3D) reconstruction, rapid prototype production, and Web-based 3D atlas construction. The corrosion cast of a lung, along with its associated arteries, veins, trachea, and bronchial tree was CT-scanned, and the data was then processed by Mimics software. Data from the lung casts were then reconstructed into 3D models using a hybrid method, utilizing both "image threshold" and "region growing." The fine structures of the bronchial tree, arterial, and venous network of the lung were clearly displayed and demonstrated their distinct relationships. The multiple divisions of bronchi and bronchopulmonary segments were identified. The 3D models were then uploaded into a rapid prototype 3D printer to physically duplicate the cast. The physically duplicated model of the lung was rescanned by CT and reconstructed to detect its production accuracy. Gross observation and accuracy detection were used to evaluate the duplication and few differences were found. Finally, Virtual Reality Modeling Language (VRML) was used to edit the 3D casting models to construct a Web-based 3D atlas accessible through Internet Explorer with 3D display and annotation functions. PMID:22653786

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

2012-05-31

70

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; Tolosa Erasmo Magalhães Castro de; Camargo Roberto de Souza; Pompeu Eduardo; Liberti Edson Aparecido

1999-01-01

71

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

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.A contribuição do ramo esternocleidomastóideo da artéria occipital para a irrigação do músculo esternocleidomastóideo foi avaliada em cadáveres humanos não fixados, através da injeção de contraste radiográfico e de resina polimerizável para estudo da microvasculatura. O músculo foi dividido nos terços superior, médio e inferior, a partir da sua inserção no processo mastóideo do osso temporal. Na maioria dos músculos, o pedículo superior apresentou-se formado por dois ramos paralelos longitudinais. Em todos os casos, o contraste radiográfico atingiu ou ultrapassou a parte média do músculo. Na parte mais distal do terço inferior, há pouca ou nenhuma contribuição do pedículo superior para a irrigação dessa região muscular sugerindo a contribuição de outros vasos para a sua irrigação. Os modelos de corrosão demonstraram a presença de uma profusa rede vascular no interior do músculo.

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

1999-01-01

72

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

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese A contribuição do ramo esternocleidomastóideo da artéria occipital para a irrigação do músculo esternocleidomastóideo foi avaliada em cadáveres humanos não fixados, através da injeção de contraste radiográfico e de resina polimerizável para estudo da microvasculatura. O músculo foi dividido nos terços superior, médio e inferior, a partir da sua inserção no processo mastóideo do osso temporal. Na maioria dos músculos, o pedículo superior apresentou-s (more) e formado por dois ramos paralelos longitudinais. Em todos os casos, o contraste radiográfico atingiu ou ultrapassou a parte média do músculo. Na parte mais distal do terço inferior, há pouca ou nenhuma contribuição do pedículo superior para a irrigação dessa região muscular sugerindo a contribuição de outros vasos para a sua irrigação. Os modelos de corrosão demonstraram a presença de uma profusa rede vascular no interior do músculo. Abstract in english The contribution of the sternocleidomastoid branch of the occipital artery (superior arterial pedicle - SAP) to the irrigation of the sternocleidomastoid muscle (SCM) was evaluated in fresh human cadavers by injecting radiological dye and a resin for microvasculature corrosion casts. From its 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 para (more) llel 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; Tolosa, Erasmo Magalhães Castro de; Camargo, Roberto de Souza; Pompeu, Eduardo; Liberti, Edson Aparecido

1999-08-01

73

Effects of austempering and graphite nodule count on corrosion resistance of spheroidal graphite cast iron; Kyujo kokuen chutetsu no taishokusei ni oyobosu austemper shori oyobi kokuen ryusu no eikyo  

Energy Technology Data Exchange (ETDEWEB)

Experiments and examinations were made on the effects of a graphite state on the corrosion characteristics of cast iron under a mild corrosive environment such as a neutral salt solution or soil. The experiments were such that spheroidal graphite cast irons with a different graphite nodule size were processed with austempering, oil hardening and ferrite treatment, and that the measurement of their corrosion potentials and their anodic polarization tests were carried out in 0.01N HCl. In addition, in the case of those austempered (ADI), the effects of a graphite nodule on corrosion resistance of spheroidal graphite cast irons were examined by varying the austempering time and quantifying the residual austenite. As a result of the experiments, the following were revealed. In spheroidal graphite cast irons, the smaller the graphite nodule, the higher the corrosion resistance. However, in ADI, the graphite nodule size had less effect on the corrosion resistance than the ferrite steel or the oil hardened steel. In ADI, the longer the austempering time, the worse the corrosion resistance. 5 refs., 14 figs., 2 tabs.

Ikenaga, A.; Nitta, Y.; Kawamoto, M. [University of Osaka Prefecture, Osaka (Japan). Faculty of Engineering

1996-07-25

74

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

International Nuclear Information System (INIS)

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

2001-01-01

75

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

Energy Technology Data Exchange (ETDEWEB)

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

Yamada, Takuyo; Negishi, Kazuo; Totsuka, Nobuo; Nakajima, Nobuo [Institute of Nuclear Safety System Inc., Mihama, Fukui (Japan)

2001-09-01

76

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

Directory of Open Access Journals (Sweden)

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

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

2009-01-01

77

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

Scientific Electronic Library Online (English)

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

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

2009-12-01

78

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1997-04-01

79

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

International Nuclear Information System (INIS)

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

2011-01-01

80

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

 
 
 
 
81

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.  

UK PubMed Central (United Kingdom)

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.

Kobayashi H; Gonda T; Uetake H; Higuchi T; Enomoto M; Sugihara K

2004-12-01

82

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

2013-01-01

83

Corrosion  

Energy Technology Data Exchange (ETDEWEB)

Electric Power Research Institute (EPRI) research programs are aimed at combating the eight varieties of corrosion in hot-gas, steam, feedwater, and coolant flow paths. The problem is aggravated by high-temperature and -pressure stresses, but a positive approach will be to develop new metals and fluids that function together. Among the techniques under study are cyclic reheat in steam plants, changes in feedwater chemistry, kinetic bonding, and new boiler designs. Cost-effectiveness is essential, but the cost of power-plant outages makes corrosion control a bargain. 5 references, 5 figures. (DCK)

Whitaker, R.; Roberts, A.; Syrett, B.

1981-09-01

84

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

International Nuclear Information System (INIS)

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

1990-01-01

85

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

International Nuclear Information System (INIS)

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

2009-01-01

86

Urinary casts  

Science.gov (United States)

Urinary casts are tiny tube-shaped particles made up of white blood cells, red blood cells, or ... your urine is healthy or abnormal. Types of urinary casts include: Fatty casts Granular casts Hyaline casts ...

87

Imaging angiogenesis and vessel pattern formation: physiological vs pathological vascularities  

Science.gov (United States)

All organs and tissues develop a highly specific vascular architecture fulfilling the individual specific demands. Therefore, the microvascular unit, characterized by inter-vessel distances or vessel density, inter-branch distances, branching angles, and vessel diameters shows significant differences in different tissues. Scanning electron microscopy of microvascular corrosion casts allows for detailed morphometric analysis of these parameters in normal and pathological tissues as well as in embryogenesis.

88

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

International Nuclear Information System (INIS)

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

2003-01-01

89

Effect of sulfate-reducing bacteria on corrosion behavior of ductile cast iron in liquid medium; Ekitai baichi ni seisokusuru ryusan`en kangenkin no kyujo kokuen chutetsu no fushoku ni oyobosu eikyo  

Energy Technology Data Exchange (ETDEWEB)

An immersion test was carried out on ductile cast iron in liquid medium in which highly active sulfur-reducing bacteria (SRB) live. This paper reports the result of discussions on the extent of effect of the SRB on corrosion of the iron by using an electrochemical method. An experiment was performed by immersing a probe (consisting of a ductile cast iron test piece as a test piece electrode and silver-silver chloride electrode as a reference electrode) in the liquid medium, and by using Desulfovibrio desulfuricans having hydrogenase activity as SRB. This paper describes the following matters: where SRB are living, corrosion rate stays at a low level (2.5 times 10 {sup -13} m/s) because a film which is very thin, but dense and highly adhesive (thought to contain a considerable amount of FeS) is produced on the test piece surface; and polarization behavior shown by the test pieces does not correspond to the corrosion rate (SRB induces cathode depolarization phenomenon on a time basis, but this phenomenon does not link directly with the increase in the corrosion rate). 13 refs., 6 figs., 2 tabs.

Kajiyama, F. [Tokyo Gas Co. Ltd., Tokyo (Japan)

1997-08-25

90

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-08-17

91

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; Murakami,Takuro; Kaneshige,Tetsuji

1987-01-01

92

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

UK PubMed Central (United Kingdom)

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 K; Murakami T; Kaneshige T

1987-08-01

93

Understanding of the corrosion behavior of a ductile cast iron exposed to the thiobacillus ferrooxidans-inoculated medium using scanning vibrating; Sosa shindo denkyoku wo mochiita tetsudanka saikin thiobacillus ferrooxidans ga seisokusuru baichichu deno kyujo kokuen chutetsu no fushoku kyodo no haaku  

Energy Technology Data Exchange (ETDEWEB)

Recently, the authors have demonstrated that iron-oxidizing bacteria have been shown to be involved in the severe corrosion of ductile cast iron pipes buried in acid-sulfate soils. However, direct evidence for the involvement of iron-oxidizing bacteria in corrosion processes has not yet well been clarified. In the present study, the involvement of iron-oxidizing bacteria in the corrosion of a ductile cast iron exposed to the Thiobacillus ferrooxidans (a species of iron-oxidizing bacteria) inoculated medium was examined by using scanning vibrating electrode technique (SVET) together with fluorescent microscope. It has been observed that the anodic regions correspond to the location of Thiobacillus ferrooxidans ; providing further evidence that severe corrosion attacked regions can be caused by the action of Thiobacillus ferrooxidans in the initial stage of corrosion processes. 8 refs., 10 figs., 2 tabs.

Aoyama, M.; Kajiyama, F. [Tokyo Gas Co. Ltd., Tokyo (Japan)

1995-12-15

94

Effect of carbon content on corrosion behavior of SCS11 duplex stainless cast steel in dilute H2SO4 solution. H2SO4 suiyoekichu ni okeru SCS11 niso stainless chuko no fushoku kyodo ni oyobosu tanso gan[prime]yuryo no eikyo  

Energy Technology Data Exchange (ETDEWEB)

With an objective to elucidate the effect of carbon content on corrosion characteristics of SCS11 duplex stainless cast steel, electrochemical measurement, submerged corrosion test, and scanning electron microscopic (SEM) observation were carried out to observe corrosion surfaces and analyze the compositions and discuss corrosion behavior. As a result, it was found that the effect of carbon content on corrosion characteristics of SCS11 stainless cast steel appears in corrosion behavior mainly in the active region, and the corrosion rate increases with an increase in the carbon content. The anodic current density in the active region for the SCS 11 stainless steel in sulfuric acid solution increased in samples with any carbon content with increasing sulfuric acid concentration and the solution temperature. Ratio of deposition of M23C6 carbide increased in the vicinity of phase boundaries as the carbon content increased in the test samples of SCS11 stainless cast steel. The corrosion rate in the active region increased in proportion to the increase in the surface area ratio of carbide deposits. 16 refs., 11 figs., 2 tabs.

Sunada, s.; Takano, S.; Sanuki, S.; Arai, K. (Toyama University, Toyama (Japan). Faculty of Engineering); Otsuka, K.; Mimata, T. (Hitachi Metals Ltd., Tokyo (Japan))

1992-08-20

95

Vascularization of the pineal complex in the lizard Tiliqua rugosa.  

Science.gov (United States)

The vascularization of the pineal complex in the lizard Tiliqua rugosa was investigated by vascular corrosion and latex casting techniques. The fine structure of the pineal capillaries was also studied by transmission electron microscopy. The pineal complex in T. rugosa consists of an elongated pineal gland proper and a separate, distinct parietal eye. The pineal complex derives an abundant blood supply from branches of the middle and posterior cerebral arteries. Scanning electron microscopy of vascular corrosion casts revealed a dense and extensive pineal capillary bed which drains ultimately into a wide longitudinal sinus suggesting an efficient pathway for the rapid removal of substances secreted by the gland. The parietal eye, which receives a unilateral left-sided blood supply from the unpaired anterior pineal artery, is shown to be a highly vascularized structure. The close morphological relationship between the pineal gland and dorsal sac, where the two structures apparently share the same blood vessels, suggests a functional relationship between them. The pineal capillaries are fenestrated with tight junctions between adjoining endothelial cells. Podia-like abluminal extensions of the endothelial cells were observed in close relation to unmyelinated nerve bundles. The basal margin of the pineal parenchyma is highly invaginated with thin finger-like cytoplasmic protrusions into the pericapillary space. Distinct bands of microfibrils form "struts" anchoring the pineal parenchyma to the endothelial wall. These features may have a role in the transfer of materials between the pineal gland and the blood stream. PMID:8363056

Teo, E H; Carati, C; Firth, B T; Barbour, R A; Gannon, B

1993-07-01

96

Vascularization of the pineal complex in the lizard Tiliqua rugosa.  

UK PubMed Central (United Kingdom)

The vascularization of the pineal complex in the lizard Tiliqua rugosa was investigated by vascular corrosion and latex casting techniques. The fine structure of the pineal capillaries was also studied by transmission electron microscopy. The pineal complex in T. rugosa consists of an elongated pineal gland proper and a separate, distinct parietal eye. The pineal complex derives an abundant blood supply from branches of the middle and posterior cerebral arteries. Scanning electron microscopy of vascular corrosion casts revealed a dense and extensive pineal capillary bed which drains ultimately into a wide longitudinal sinus suggesting an efficient pathway for the rapid removal of substances secreted by the gland. The parietal eye, which receives a unilateral left-sided blood supply from the unpaired anterior pineal artery, is shown to be a highly vascularized structure. The close morphological relationship between the pineal gland and dorsal sac, where the two structures apparently share the same blood vessels, suggests a functional relationship between them. The pineal capillaries are fenestrated with tight junctions between adjoining endothelial cells. Podia-like abluminal extensions of the endothelial cells were observed in close relation to unmyelinated nerve bundles. The basal margin of the pineal parenchyma is highly invaginated with thin finger-like cytoplasmic protrusions into the pericapillary space. Distinct bands of microfibrils form "struts" anchoring the pineal parenchyma to the endothelial wall. These features may have a role in the transfer of materials between the pineal gland and the blood stream.

Teo EH; Carati C; Firth BT; Barbour RA; Gannon B

1993-07-01

97

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.

2009-04-03

98

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1998-05-25

99

Bimetallic layered castings alloy steel – grey cast iron  

Directory of Open Access Journals (Sweden)

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

2011-01-01

100

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)

[en] 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.

2012-02-15

 
 
 
 
101

Deoxidation casting, aluminium casting and casting equipment  

UK PubMed Central (United Kingdom)

A deoxidized casting method for removing the oxidized film on the surface of molten metal to obtain high quality of castings includes such steps as preparing deoxidant by reaction between metallic vapor and inactive gas, and reaction between said deoxidant and molten metal.

KOICHI TOMO KEISUKE OGIHARA

102

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

Directory of Open Access Journals (Sweden)

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; Li Shuangshou; Huang Tianyou

2011-01-01

103

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

International Nuclear Information System (INIS)

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

1984-01-01

104

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

UK PubMed Central (United Kingdom)

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.

Ruhl AS; Jekel M

2013-07-01

105

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

2013-07-27

106

Investment casting  

Energy Technology Data Exchange (ETDEWEB)

Materials and manufacturing technologies for investment casting have made impressive gains over the past several years, resulting in higher productivity, shorter lead times, and superior castings. To improve efficiency, investment casters have applied total quality control methods, new management concepts, and computer controls. Management and production efficiency improvements have been critical factors in maintaining and expanding market share.

Bidwell, H.T. [Investment Casting Inst., Dallas, TX (United States)

1996-04-01

107

Evaluation of couple/crevice corrosion by prosthetic alloys under in vivo conditions.  

UK PubMed Central (United Kingdom)

Alloys of cast Co-Cr-Mo, wrought Co-Cr-W, wrought, Co-Ni-Cr-Mo(MP35N), Ti-60% Al-4% V, and graphite were incorporated in specimens which simulated both a couple and a crevice corrosion condition. These specimens were implanted in a dog for 30 months. Post-sacrifice examination showed no substantial evidence of corrosion activity on the surfaces of the metals except for a tarnish film on the titanium alloy specimens. The presence of the tarnish film is taken as more evidence of corrosion activity and this correlated with a thicker average fibrous membrane, cellular activity in and near the fibrous membrane, and some increased vascularity. These must be regarded as preliminary observations.

Rostoker W; Galante JO; Lereim P

1978-11-01

108

Anodization of cast aluminium alloys produced by different casting methods  

Directory of Open Access Journals (Sweden)

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; L.A. Dobrza?ski; J. Konieczny

2008-01-01

109

Selected properties of new „duplex” cast steel  

Directory of Open Access Journals (Sweden)

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

S. Pietrowski; G. Gumienny; M. Masalski

2011-01-01

110

Corrosion Susceptibilities of Magnesium Alloys AZ91, EZ33 and ZE41.  

Science.gov (United States)

An assessment was made of the corrosion susceptibility of cast magnesium alloys AZ91C-T6, EZ33A-T5 and ZE41A-T5. Efforts were made to establish the influence of as-cast and machined surfaces on the corrosion behavior. Cast test panels of AZ91C-T6 alloy we...

A. Gallaccio W. T. Ebihara

1983-01-01

111

Investment casting  

UK PubMed Central (United Kingdom)

Methods are provided for producing investment cast articles, such as orthopedic implants, or portions thereof, having at least a partially textured surface that is formed during casting of the article. In an exemplary method, a textured metal casting is produced by creating a heat destructible pattern and spraying the pattern with a texturing material to cause the texturing material to form a textured surface on at least a portion of the pattern. In another embodiment, a textured template is pressed against a heat softenable pattern to provide a textured pattern. With respect to each of these methods, a shell is the created around the textured pattern to form a mold, and the pattern is removed from the shell. Molten metal is introduced into the mold and allowed to harden, after which the mold is removed. In yet another embodiment a textured pattern for investment casting is provided by creating a textured model and enveloping it with a resilient material to create a resilient mold. The textured model is removed from the resilient mold and the mold is filled with investment casting wax to create a textured pattern.

Mastrorio Brooke W.; Fifolt Douglas A.

112

Investment casting  

UK PubMed Central (United Kingdom)

Methods are provided for producing investment cast articles, such as orthopedic implants, or portions thereof, having at least a partially textured surface that is formed during casting of the article. In an exemplary method, a textured metal casting is produced by creating a heat destructible pattern and spraying the pattern with a texturing material to cause the texturing material to form a textured surface on at least a portion of the pattern. In another embodiment, a textured template is pressed against a heat softenable pattern to provide a textured pattern. With respect to each of these methods, a shell is the created around the textured pattern to form a mold, and the pattern is removed from the shell. Molten metal is introduced into the mold and allowed to harden, after which the mold is removed.

Mastrorio Brooke W.; Fifolt Douglas A.

113

Corrosion Performance of Concrete Cylinder Piles.  

Science.gov (United States)

Cylinder bridge piles that are produced by a centrifugally cast, vibrated, roller compacted process (also known as Raymond piles) have shown promising resistance to reinforcement corrosion in an earlier Florida Department of Transportation (FDOT) field in...

K. Lau A. A. Sagues L. Yao

2005-01-01

114

Electromagnetic casting  

Energy Technology Data Exchange (ETDEWEB)

Electromagnetic casting (EMC) is a technology that is used extensively in the aluminum industry to cast ingots with good surface finish for subsequent rolling into consumer product. The paper reviews briefly some investigations from the eighties wherein models for EMC were developed. Then more recent work is examined wherein more realistic 3D models have been developed, the traditional studies of electromagnetic and magnetohydrodynamic phenomena have been supplemented with research on heat transport, and the stability of the metal free surface has been examined. The paper concludes with three generalizations concerning modeling that may have wider applicability than EMC.

Evans, J.W.; Kageyama, R. [Univ. of California, Berkeley, CA (United States); Deepak [Motorola Corp., Phoenix, AZ (United States); Cook, D.P. [Reynolds Metals Co., Richmond, VA (United States); Prasso, D.C. [Intel Corp., Aloha, OR (United States); Nishioka, S. [NKK Corp., Kawasaki (Japan)

1995-12-31

115

[Infrared casting temperature control of the induction centrifuge casting exemplary in the non-precious dental alloy Wiron 88  

UK PubMed Central (United Kingdom)

A temperature-dependent, IR-controlled casting technology for the non-precious dental alloy Wiron 88 (Bego) is presented and compared with a traditional procedure. The new casting allows the production of cast objects with favourable and reproducible material properties. Compared with the commonly used technology hardness, grain size and susceptibility to corrosion could be reduced. Texture after casting was found to be homogeneous. The procedure presented meets the requirements for a modern casting technology and be adapted to older automatic casating devices.

Müller WD; Lotz J; Lange KP; Altrichter B

1991-01-01

116

The surface layer of austempered ductile iron investment castings properties  

Directory of Open Access Journals (Sweden)

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

D. Myszka; M. K??bczyk; A. Zych; L. Kwiatkowski

2009-01-01

117

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

Science.gov (United States)

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

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

2010-04-01

118

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

UK PubMed Central (United Kingdom)

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

Pouponneau P; Savadogo O; Napporn T; Yahia L; Martel S

2010-04-01

119

Material tests on municipal gas distribution equipment made of cast iron  

Energy Technology Data Exchange (ETDEWEB)

In order to find further criteria for determining the importance of repair measures in underground gas pipelines of cast iron, material tests have been carried out in cast iron samples from pipelines. The results are given. They show that significant corrosion effects can also be found in cast iron.

Altmann, W.; Kronschnabl, S. (Institut fuer Energieversorgung, Leipzig (German Democratic Republic). Forschungsbereich Gasversorgung)

1980-01-01

120

Pd-Co dental casting ferromagnetic alloys.  

UK PubMed Central (United Kingdom)

Three kinds of Pd-Co alloys have been newly developed. Their magnetic and physical properties and corrosion resistances have been examined. As a result, it was found that they are available as the dental casting ferromagnetic alloy which can be used in combination with Sm-Co magnets, overcoming such problems as non-castability and brittleness.

Kinouchi Y; Ushita T; Tsutsui H; Yoshida Y; Sasaki H; Miyazaki T

1981-01-01

 
 
 
 
121

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; C. Rapiejko

2008-01-01

122

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

123

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

Directory of Open Access Journals (Sweden)

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

A Hodži?; A Zuko; R Avdi?; A Ali?; J Omeragi?; A Jaži?

2013-01-01

124

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

UK PubMed Central (United Kingdom)

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.

Hodži? A; Zuko A; Avdi? R; Ali? A; Omeragi? J; Jaži? A

2013-01-01

125

Corrosion induced hydrogen evolution on high level waste overpack materials in synthetic groundwaters and chloride solutions  

International Nuclear Information System (INIS)

[en] Hydrogen evolution from anoxic corrosion of cast steel overpacks in high-level waste repositories is an important issue for design if, as has been estimated, the hydrogen is prevented from escaping by diffusion by a low permeability compacted bentonite backfill. Evaluation of the corrosion results show three basic types of corrosion behavior: general corrosion with oxide layer formation, unstable corrosion behavior with pitting or macro-element formation and stable passive behavior. Cast steel containers under Swiss repositiory conditions are expectd to suffer general corrosion with oxide layer formation. This behavior gives the highest long term corrosion rates without local attack

1989-01-01

126

Reference series of radiographs of casting defects in chemical apparatus made of grey cast iron  

Energy Technology Data Exchange (ETDEWEB)

Chemical apparatus of grey cast iron as reaction vessels or storage tanks continue to be of major importance. When subjected to corrosive attack, they must not show excessive casting defects, otherwise the wall thickness will be reduced too much locally. Radiographic testing is generally used for the quality inspection of such apparatus. In order to evaluate casting defects in radiographs, a reference series of radiographs was produced and its system discussed. This series enables not only an evaluation of radiographs, but also makes it possible to fix quality requirements.

Gerischer, K.; Obser, J.; Cavalar, K.O.

1982-03-01

127

Hair casts.  

Science.gov (United States)

A case of hair casts in an 8-year-old girl is described. The disorder is rare, the first description dating back to 1897 with a total of only 31 cases reported in the literature since then. The results of research conducted using the optic and electron microscopes (transmission and scanning) are recorded. These studies show that the typical lesion consists of two concentric layers of keratinized cells of differing structure: one resembling the inner layer of Huxley's sheath and the outer layer resembling Henle's layer. PMID:2455695

Fabbri, P; Difonzo, E M; Palleschi, G M; Pacini, P

1988-06-01

128

Hair casts.  

UK PubMed Central (United Kingdom)

A case of hair casts in an 8-year-old girl is described. The disorder is rare, the first description dating back to 1897 with a total of only 31 cases reported in the literature since then. The results of research conducted using the optic and electron microscopes (transmission and scanning) are recorded. These studies show that the typical lesion consists of two concentric layers of keratinized cells of differing structure: one resembling the inner layer of Huxley's sheath and the outer layer resembling Henle's layer.

Fabbri P; Difonzo EM; Palleschi GM; Pacini P

1988-06-01

129

Casting materials  

Energy Technology Data Exchange (ETDEWEB)

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

130

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; R. Babilas

2007-01-01

131

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; P. Wróbel; T. Wróbel

2007-01-01

132

Extraglandular and intraglandular vascularization of canine prostate.  

UK PubMed Central (United Kingdom)

The literature on the vascularization of the canine prostate is reviewed and the clinical significance of prostate morphology is described. Scanning Electron Microscopy (SEM), combined with improved corrosion casting methods, reveal new morphological details that promise better diagnostics and treatment but also require expansion of clinical nomenclature. A proposal is made for including two previously unnamed veins in Nomina Anatomica Veterinaria (NAV). The canine prostate has two lobes with independent vascularization. Each lobe is supplied through the left and right a. prostatica, respectively. The a. prostatica sprouts three small vessels (cranial, middle, and caudal) towards the prostate gland. A. prostatica is a small-size artery whose wall structure is similar to the arteries of the muscular type. V. prostatica is a small-size valved vein. The canine prostate has capsular, parenchymal, and urethral vascular zones. The surface vessels of the capsule are predominantly veins and the diameter of arterial vessels is larger than that of the veins. The trabecular vessels are of two types: direct and branched. The prostate parenchyma is supplied by branches of the trabecular vessels. The periacinary capillaries are fenestrated and form a net in a circular pattern. The processes of the myoepithelial cells embrace both the acins and the periacinar capillaries. In the prostate ductal system. there are spermatozoa. The prostatic part of the urethra is supplied by an independent branch of a. prostatica. The prostatic urethral part is drained by v. prostatica, the vein of the urethral bulb and the ventral prostate veins. M. urethralis begins as early as the urethral prostatic part. The greater part of the white muscle fibers in m. urethralis suggest an enhanced anaerobic metabolism.

Stefanov M

2004-03-01

133

Inhibition by phosphates of mild steel and cast iron in cooling water  

Energy Technology Data Exchange (ETDEWEB)

The effectiveness of corrosion inhibition of mild steel and cast iron in cooling water systems by phosphonates has been studied by electrochemical techniques and weight-loss tests. The following phosphonates were investigated: aminotrimethylene phosphonate (AMP), 1-hydroxyethylene 1,1-diphosphonate (HEDP), and 2-phosphonobutane 1,2,4-tricarboxylic acid (PBTA). It was shown that corrosion inhibition of mild steel can be achieved with lower concentrations of phosphonates as compared to corrosion inhibition of cast iron. BC-80, a new inhibitor that protects mild steel, cast iron, and copper alloys in cooling water systems, was developed and tested in laboratory and field conditions.

Starostina, M.; Smorodin, A.; Gal-Or, L. (Israel Inst. of Metals (Israel))

1999-03-01

134

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

135

An investigation of soil corrosion in the Arabian Gulf region  

Energy Technology Data Exchange (ETDEWEB)

A corrosion survey of the buried structures in a ``pilot`` area in the western coast of the Arabian Gulf showed that, in less than ten years of construction, metallic structures such as galvanized steel, ductile iron, cast iron and carbon steel with thin bituminous coating exhibited severe general corrosion and pitting. In order to substantiate the survey results, coupons made of mild steel, cast iron, galvanized cast iron, copper, brass and stainless steel were installed in three locations and kept buried for over three years. Coupons were retrieved after 435 days and 1,165 days of burial and corrosion of the coupons was determined by the gravimetric weight loss method. The results showed that exposure Site 16 has the most corrosive soil. The cast iron, mild steel, and galvanized cast iron coupons experienced severe corrosion at the three burial sites. The corrosion rates of these materials in burial Site 16 were 13.4, 9.2 and 7.1 mpy (340, 234 and 180 {micro}m/y) respectively, after 1,165 days of exposure. The cast iron coupons corroded by severe graphitization covering 30-90% of the exposed surface and severe pitting 5-37 mils (127--940 {micro}m) deep. The mild steel coupons suffered severe general corrosion and pitting, with pits as deep as 50 mils (1,270 {micro}m). The galvanized cast iron coupons also had severe corrosion and pitting. Pitting was severe, especially at the edges, and the pit depths ranged between 10 and 50 mils (254 and 1,270 {micro}m). The brass and copper coupons showed only mild corrosion. The stainless steel coupons were the best performers among the materials tested. They did not have any measurable corrosion.

Saricimen, H.; Shamim, M.; Al-Mana, A.I. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Research Inst.

1994-12-31

136

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

137

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

138

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.

1996-01-01

139

Corrosive wear principles  

Energy Technology Data Exchange (ETDEWEB)

The dual effects of corrosion and wear operate together in such industries as paper and pulp, coal handling, mining, and sugar beet extraction. There is a synergistic effect that causes far greater wastage to carbon steels, alloy steels, and even much more abrasion resistant cast irons. Several laboratory and in situ studies have been conducted to better understand the contributions of corrosion and wear to the wastage process. The environmental conditions are usually set by the process. However, there are a few instances where inhibitors as sodium nitrite, sodium chromate, and sodium metasilicate have been successfully used to reduce metal wastage of carbon steels. Hardness has been found to be an unreliable guide to performance under wet sliding conditions. Heat treated alloy steels and cast irons are inferior to stainless steels. Even distilled water is too severe a corrodent for steels. While the austenitic stainlesses perform the best, cold rolling to increase hardness does not further improve their performance. The surface roughness of stainless steels gets smoother during corrosive wear testing while it gets rougher for the alloy steels. This observation substantiated the reputation of improved slideability for stainless alloys over alloy steels.

Schumacher, W.J. [Armco Inc., Middletown, OH (United States)

1993-12-31

140

Corrosion cracking  

Energy Technology Data Exchange (ETDEWEB)

This book presents the papers given at a conference on alloy corrosion cracking. Topics considered at the conference included the effect of niobium addition on intergranular stress corrosion cracking, corrosion-fatigue cracking in fossil-fueled-boilers, fracture toughness, fracture modes, hydrogen-induced thresholds, electrochemical and hydrogen permeation studies, the effect of seawater on fatigue crack propagation of wells for offshore structures, the corrosion fatigue of carbon steels in seawater, and stress corrosion cracking and the mechanical strength of alloy 600.

Goel, V.S.

1985-01-01

 
 
 
 
141

Thermomechanical properties of fused and cast chrome-corundum refractories  

Energy Technology Data Exchange (ETDEWEB)

The thermomechanical properties and heat resistance of fused and cast chrome-corundum refractories, which are distinguished by their increased corrosion resistance to the action of the aggressive gaseous medium in the production of glass, were investigated. On the basis of the investigations conducted the service properties of chrome-corundum refractories were determined and recommendations were made for selection of the optimum chemical composition of the fused and cast material in relation to service conditions.

Popov, O.N.; Tokarev, Yu.S.; Martynov, V.P.; Kolomeitsev, V.V.

1987-03-01

142

Corrosion engineering  

Energy Technology Data Exchange (ETDEWEB)

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

Fontana, M.G.

1986-01-01

143

Cast bone ingrowth surface  

UK PubMed Central (United Kingdom)

A prosthetic part for use as an orthopaedic implant has a cast metal base member 20' and a tissue ingrowth surface spaced outwardly therefrom. The tissue ingrowth surface is in the form of a cast metal lattice element 10' which covers at least a part of the outer surface of the base member 20'. The cast metal lattice element 10' is cast simultaneously and integrally with the base member from the same metal. This metal may be any well known castable material for ortho-paedic implants such as Vitallium or titanium. The lattice element 10' is in the form of a grid-like mesh which includes spacer members 16' cast integrally with the wire mesh and the base member to space the lattice element 10' a predetermined distance above the prosthesis surface 18'. An investment casting technique wherein a meltable material is coated with a ceramic casting shell is utilized to produce the integrally cast orthopaedic implant and tissue ingrowth surface.

Gustavson Larry J.; Schwartz Melvin M.

144

Cast bone ingrowth surface  

UK PubMed Central (United Kingdom)

A prosthetic part for use as an orthopaedic implant has a cast metal base member and a tissue ingrowth surface spaced outwardly therefrom. The tissue ingrowth surface is in the form of a cast metal lattice element which covers at least a part of the outer surface of the base member. The cast metal lattice element is cast simultaneously and integrally with the base member from the same metal. This metal may be any well known castable material for orthopaedic implants such as Vitallium or titanium. The lattice element is in the form of a grid-like mesh which includes spaced members cast integrally with the wire mesh and the base member to space the lattice element a predetermined distance above the prosthesis surface. An investment casting technique wherein a meltable material is coated with a ceramic casting shell is utilized to produce the integrally cast orthopaedic implant and tissue ingrowth surface.

GUSTAVSON LARRY J; SCHWARTZ MELVIN M

145

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; I. Kurytnik

2008-01-01

146

LLNL casting technology  

Energy Technology Data Exchange (ETDEWEB)

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

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

1994-01-01

147

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).

M. Gajewski; J. Kasi?ska

2008-01-01

148

Corrosion management  

Energy Technology Data Exchange (ETDEWEB)

The management of corrosion is a challenge at the design stage and for the multi-disciplined team of operations, maintenance, inspection, and materials and corrosion engineering staff concerned with everyday oil production and refining operations. Only when their efforts are successfully combined can the technical integrity of manufacturing installations be ensured at minimum life cycle costs. The paper describes a model for corrosion management and the tools to achieve the management of corrosion.

Milliams, D.E. [Shell International Exploration and Production, The Hague (Netherlands); Gelder, K. van [Petroleum Development Oman, Muscat (Oman)

1996-11-01

149

High quality casting materials  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The paper briefly presents results of the new developed high quality cast materials.Design/methodology/approach: The following materials are: hypereutectoid cast steel with various microstructure modular graphite obtained in as-cast condition (raw state), ductile cast iron of bainite-martensitic carbides structure obtained in a raw state, aluminum bronzes and silumins with additives of: chromium, molybdenum, wolfram, vanadium.Findings: These alloys are characterized primarily by significant mechanical properties and high wear resistance. It was also discussed getting of layer products by combination of steel or cast iron using alphinated layer with silumin.Practical implications: The paper discusses the high quality cast alloy, layer products and presents the high quality casting materials in the point of view principles of materials selection.Originality/value: The above problem is shown in the background of “Rules of material selection” as well as a model of production system in company.

S. Pietrowski

2010-01-01

150

Fatigue properties and corrosion resistance of spheroidal graphite cast iron surface-hardened by TIG arc remelting; TIG aku saiyoyuho ni yori hyomen kokashita kyujo kokuen chutetsu no tsukare tokusei to taifushokusei  

Energy Technology Data Exchange (ETDEWEB)

As a surface reforming method utilized the solidification character of a cast iron, remelting a cast iron surface locally by the tungsten inert gas (TIG) arc, so called a remelting surface hardening method is being paid attention. Because this method can achieve a saving of the alloy elements, and a simplicity and convenience of the manipulation, or can make only a desired part remarkably hardened and microstructured compared to the other surface hardening methods, it can give an excellent rolling contact fatigue resistant character, sliding wear resistant character, or a scuffing resistant character by doing so. Therefore it is being applied for the sliding parts of every kind of the internal combustion engines including the automobiles. In this report, a fatigue character of the spheroidal graphite cast iron surface-hardened by a TIG arc remelting method was investigated through using an actual piston ring fatigue test machine. As a consequence the followings were found: A fatigue limit of the piston ring treated by remelting hardening was improved more than 10% compared to untreated specimens. However, the ones plated by Cr dropped than that of untreated specimens and so forth. 18 refs., 13 figs., 2 tabs.

Hiraoka, T. [Nippon Piston Ring Co. Ltd., Tokyo (Japan); Tanaka, Y. [Muroran Inst. of Technology, Hokkaido (Japan)

1994-09-25

151

Advances in aluminum casting technology  

Energy Technology Data Exchange (ETDEWEB)

This symposium focuses on the improvements of aluminum casting quality and reliability through a better understanding of processes and process variables, and explores the latest innovations in casting-process design that allow increasing use of the castings to replace complex assemblies and heavy steel and cast-iron components in aerospace and automotive applications. Presented are 35 papers by international experts in the various aspects of the subject. The contents include: Semisolid casting; Computer-aided designing of molds and castings; Casting-process modeling; Aluminum-matrix composite castings; HIPing of castings; Progress in the US car project; Die casting and die design; and Solidification and properties.

Tiryakioglu, M.; Campbell, J. (eds.)

1998-01-01

152

Corrosion cracking  

International Nuclear Information System (INIS)

[en] This book presents the papers given at a conference on alloy corrosion cracking. Topics considered at the conference included the effect of niobium addition on intergranular stress corrosion cracking, corrosion-fatigue cracking in fossil-fueled-boilers, fracture toughness, fracture modes, hydrogen-induced thresholds, electrochemical and hydrogen permeation studies, the effect of seawater on fatigue crack propagation of wells for offshore structures, the corrosion fatigue of carbon steels in seawater, and stress corrosion cracking and the mechanical strength of alloy 600

1985-01-01

153

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; M. Kondracki; J. Szajnar

2012-01-01

154

Shadow corrosion or crevice corrosion?  

International Nuclear Information System (INIS)

Local corrosion phenomena in proximity to other components may have different reasons. In narrow gaps, crevice corrosion can be formed under BWR and to a lesser degree under PWR conditions independent of the counter material. At positions, where dissimilar metals are close to Zry under oxidizing conditions, shadow corrosion, driven by large potential differences, can occur.

2001-01-01

155

Shadow corrosion or crevice corrosion?  

Energy Technology Data Exchange (ETDEWEB)

Local corrosion phenomena in proximity to other components may have different reasons. In narrow gaps, crevice corrosion can be formed under BWR and to a lesser degree under PWR conditions independent of the counter material. At positions, where dissimilar metals are close to Zry under oxidizing conditions, shadow corrosion, driven by large potential differences, can occur.

Garzarolli, F. E-mail: friedrich.garzarolli@framatome-anp.de; Hoffmann, P.B.; Seibold, A

2001-03-01

156

Vascular Dementia  

Science.gov (United States)

... be reprinted for personal, noncommercial use only. Vascular dementia By Mayo Clinic staff Original Article: http://www.mayoclinic.com/health/vascular-dementia/DS00934 Definition Symptoms Causes Risk factors Preparing for ...

157

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).

1988-01-01

158

Cast vs. wrought cobalt-chromium surgical implant alloys.  

UK PubMed Central (United Kingdom)

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.

Devine TM; Wulff J

1975-03-01

159

Endothelial NO synthase augments fetoplacental blood flow, placental vascularization, and fetal growth in mice.  

UK PubMed Central (United Kingdom)

It is not known whether eNOS deficiency in the mother or the conceptus (ie, placenta and fetus) causes fetal growth restriction in mice lacking the endothelial NO synthase gene (eNOS knockout [KO]). We hypothesized that eNOS sustains fetal growth by maintaining low fetoplacental vascular tone and promoting fetoplacental vascularity and that this is a conceptus effect and is independent of maternal genotype. We found that eNOS deficiency blunted fetal growth, and blunted the normal increase in umbilical blood flow and umbilical venous diameter and the decrease in umbilical arterial Resistance Index in late gestation (14.5-17.5 days) in eNOS KO relative to C57Bl/6J controls. On day 17.5, fetoplacental capillary lobule length and capillary density in vascular corrosion casts were reduced in eNOS KO placentas. Reduced vascularization may be a result of decreased vascular endothelial growth factor mRNA and protein expression in eNOS KO placentas at this stage. These factors, combined with significant anemia found in eNOS KO fetuses, would be anticipated to reduce fetal oxygen delivery and contribute to the fetal tissue hypoxia that was detected in the heart, lung, kidney, and liver by immunohistochemistry using pimonidazole. Although maternal eNOS deficiency impairs uteroplacental adaptations to pregnancy, maternal genotype was not a significant factor affecting growth in heterozygous conceptuses. This indicates that fetal growth restriction was primarily caused by conceptus eNOS deficiency. In mice, placental hemodynamic and vascular changes with gestation and growth restriction showed strong parallels with human pregnancy. Thus, the eNOS KO model could provide insights into the pathogenesis of human intrauterine growth restriction.

Kulandavelu S; Whiteley KJ; Bainbridge SA; Qu D; Adamson SL

2013-01-01

160

Endothelial NO synthase augments fetoplacental blood flow, placental vascularization, and fetal growth in mice.  

Science.gov (United States)

It is not known whether eNOS deficiency in the mother or the conceptus (ie, placenta and fetus) causes fetal growth restriction in mice lacking the endothelial NO synthase gene (eNOS knockout [KO]). We hypothesized that eNOS sustains fetal growth by maintaining low fetoplacental vascular tone and promoting fetoplacental vascularity and that this is a conceptus effect and is independent of maternal genotype. We found that eNOS deficiency blunted fetal growth, and blunted the normal increase in umbilical blood flow and umbilical venous diameter and the decrease in umbilical arterial Resistance Index in late gestation (14.5-17.5 days) in eNOS KO relative to C57Bl/6J controls. On day 17.5, fetoplacental capillary lobule length and capillary density in vascular corrosion casts were reduced in eNOS KO placentas. Reduced vascularization may be a result of decreased vascular endothelial growth factor mRNA and protein expression in eNOS KO placentas at this stage. These factors, combined with significant anemia found in eNOS KO fetuses, would be anticipated to reduce fetal oxygen delivery and contribute to the fetal tissue hypoxia that was detected in the heart, lung, kidney, and liver by immunohistochemistry using pimonidazole. Although maternal eNOS deficiency impairs uteroplacental adaptations to pregnancy, maternal genotype was not a significant factor affecting growth in heterozygous conceptuses. This indicates that fetal growth restriction was primarily caused by conceptus eNOS deficiency. In mice, placental hemodynamic and vascular changes with gestation and growth restriction showed strong parallels with human pregnancy. Thus, the eNOS KO model could provide insights into the pathogenesis of human intrauterine growth restriction. PMID:23150513

Kulandavelu, Shathiyah; Whiteley, Kathie J; Bainbridge, Shannon A; Qu, Dawei; Adamson, S Lee

2012-11-12

 
 
 
 
161

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; K. Labisz; J. Wieczorek; L. A. Dobrza?ski

2008-01-01

162

High pressure infiltration casting: manufacturing net shape composites with a unique interface  

Energy Technology Data Exchange (ETDEWEB)

An overview of the major casting-based manufacturing techniques of metal matrix composites is presented. These techniques include compocasting (rheocasting), squeeze casting, infiltration, investment casting and pressure casting (squeeze infiltration casting). This is followed by a detailed description of the high pressure infiltration casting (HiPIC) recently developed at the Applied Research Laboratory of the Pennsylvania State University. HiPIC uses a rapid application of a relatively high pressure (above 100 MPa) to force-infiltrate molten metal into fiber pre-forms. Reaction between fiber and matrix metal is negligible and the cast composites are free from voids, gas porosity and shrinkage cavities. Experimental results on tensile strength, stiffness, low cycle fatigue, fracture toughness, damping and corrosion resistance of the HiPIC composites are summarized and discussed. (orig.).

Bhagat, R.B. (Dept. of Engineering Science and Mechanics, Pennsylvania State Univ., University Park (United States))

1991-10-01

163

Corrosion mechanisms  

Energy Technology Data Exchange (ETDEWEB)

Stressing experimental and theoretical results, this book discusses the dissolution kinetics and mechanisms of the iron group metals in the active state (including a new iron mechanism, which also has applications for nickel and cobalt); offers a practical overview of alloy dissolution; presents major approaches to corrosion protection through the use of inhibitors and coatings; explores atmospheric corrosion on steel, zinc, aluminum, and copper, including the effects of acid rain; and describes localized corrosion, emphasizing the initiation and growth of pits.

Mansfield, F.

1987-01-01

164

Combatting corrosion  

Energy Technology Data Exchange (ETDEWEB)

The importance of the selection of construction materials in a modern refinery and the significance of corrosion resistance, mechanical properties, and economics are discussed. The three most commonly encountered corrosion mechanisms namely sulphide attack, polythionic acid induced stress corrosion cracking and chloride induced stress corrosion cracking are examined, and materials used to combat high temperature hydrogen sulphide in refineries ranging from carbon steel to high nickel alloys are explored. The unique combination of properties offered by nickel base alloy tubes are considered, and the results of the evaluating different nickel base alloys are summarised.

Shoemaker, L.; Tassen, S. [Special Metals Co. (United States); Barr, K. [Special Metals Wiggin Ltd. (United Kingdom)

2002-01-01

165

Vascular inner ear partition: a concept for some forms of sensorineural hearing loss and vertigo.  

UK PubMed Central (United Kingdom)

The results of a series of scanning electron microscopical studies were used to construct a model for the vascular pathways in the inner ear. Corrosion cast preparations of the vessels of the inner ear of the adult rat were used in this study. The inner ear is, like a hand, an end organ containing four sense organs (cochlea, saccule, utricle and the cristae ampullaris). All these specific inner ear structures have their own vascular supply. We have developed a blood flow diagram of the inner ear. This model was used for a classification of different types of ischemia in the inner ear and forms a concept for some forms of sensorineural hearing loss and vertigo. Four types of inner ear ischemia are proposed. In type I (a or b) of inner ear ischemia only the vessels of the cochlea are involved resulting in two types of hearing loss without vertigo. Type II is characterized by ischemia of a part of the cochlea and a part of the vestibular system. In type III (a or b) only the vestibular system is involved, while in type IV no blood circulation will be present in the inner ear resulting in total deafness and severe vertigo. Inner ear partition at ultramicroscopical level of these structures may be possible in the future and new imaging techniques will probably support the vascular schematic model presented in this study.

Tange RA

1998-03-01

166

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

Scientific Electronic Library Online (English)

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

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

2006-10-01

167

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

Directory of Open Access Journals (Sweden)

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

Zilton A Andrade; Ana Paula Baptista; Thaynã Souto Santana

2006-01-01

168

Corrosion behaviour of dental metals and alloys in different media.  

UK PubMed Central (United Kingdom)

The corrosion tendencies of metals are related with their position in the electromotive series. These electrode potential degrees may change due to the compositions of the alloys, the surrounding media, or due to alterations in the composition because of recurrent casting. Therefore in this research, the electrode potentials and their changes over a period of time were measured in different pH media simulating the oral electrochemical conditions in vitro. The surface structure of the first and second castings of 29 different dental metals and alloys were examined under a scanning electron microscope and their composition in percentage weight was calculated by the Energy-dispersive X-ray Analysor system. Further the current-potential curves of the dental alloys were found by the potentiodynamic method in three different solutions and, in addition, the changes of corrosion potentials over time were also determined. The corrosion rates, corrosion potentials, their changes over time and their cathodic Tafel slopes were determined. All alloys tested showed ion leakage in corrosive media. Titanium exhibited the least, but alloys with tin and cobalt content displayed the greatest corrosion tendencies. Alloys with iron and copper corroded in the acid media, conversely alloys containing chromium, nichel and molybdenum proved to be resistant to corrosion. The recurrent castings were also corrosion resistant.

Kedici SP; Aksüt AA; Kílíçarslan MA; Bayramo?lu G; Gökdemir K

1998-10-01

169

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

Science.gov (United States)

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

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

1990-03-01

170

Degradation of stainless castings. A literature study  

International Nuclear Information System (INIS)

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

1995-01-01

171

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; T. Wróbel; S. Tenerowicz

2010-01-01

172

Higher Education's Caste System  

Science.gov (United States)

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

Iannone, Ron

2004-01-01

173

Modern applications for cast and wrought superalloys  

International Nuclear Information System (INIS)

[en] This paper covers casting and wrought alloys for gas turbines, alloys for power generation (nuclear applications), automotive applications, alloys for corrosion resistance, and hot working tools. The section on nuclear applications includes references to the use of a niobium stabilised 20 Cr - 25 Ni Nb austenitic stainless steel for fuel cladding for the A.G.R., and other alloys based on chromium and nickel for such purposes as fuel element components for the P.F.R. and bolts in steam turbine plant. (U.K.)

1978-01-01

174

Corrosion Engineering.  

Science.gov (United States)

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

White, Charles V.

175

A study of differential-flow-rate-cell corrosion in seawater  

Energy Technology Data Exchange (ETDEWEB)

Mechanisms of differential-flow-rate-cell corrosion (differential-aeration-cell corrosion caused by differential flow rates) of cast iron in seawater were studied. Potential and current density distributions produced by the differential-flow-rate-cell were on actual pumps and a model test cell. Boundary element analysis was also performed on differential-flow-rate-cell corrosion occurred in the model test cell. These studies demonstrate that differential-flow-rate-cell corrosion has characteristics similar to those of galvanic corrosion, and thus can be treated in the same manner as galvanic corrosion.

Miyasaka, M. [Ebara Research Co., Ltd., Fujisawa, Kanagawa (Japan). Center for Fluids and Mechanical Engineering; Kishimoto, K.; Aoki, S. [Tokyo Inst. of Tech. (Japan)

1995-10-01

176

Orthopedic cast construction  

UK PubMed Central (United Kingdom)

An improved orthopedic cast construction is disclosed. It is intended for application to broken bones, sprains, etc. The improved construction utilizes an elastic sleeve for those instances where the cast is placed on a limb, a second layer of spooled felting material which serves as a buffer against the elastic sleeve, and a third layer formed of a plaster bandage which is applied in multiple wraps soaked in water for the purpose of hardening into a supportive cast. The improvement comprises a felted layer of polyester or cotton fibers with ground silica-gel to adsorb perspiration from the body to keep the cast dry after installation and draws water out of the plaster media to enhance its drying. This protects and extends the life of the cast. It improves comfort to the patient.

SAIN BERNARD S

177

Multi-layers castings  

Directory of Open Access Journals (Sweden)

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

J. Szajnar; P. Wróbel; T. Wróbel

2010-01-01

178

Vascular Access Procedures  

Science.gov (United States)

Vascular Access Procedures Play Video Clip (00:03:16) Your Radiologist Explains Vascular Access Procedures What are Vascular Access ... limitations of Vascular Access Procedures? What are Vascular Access Procedures? A vascular access procedure involves the insertion ...

179

Corrosion sensors  

Science.gov (United States)

Corrosion of thin metal films in electronic components has attracted much attention because it can cause catastrophic device failure. Adsorbed moisture layers, oxygen and trace amounts of contaminants are sufficient to initiate corrosion. Corrosion is also hard to eliminate because materials that are chosen for their special electrical, magnetic, or optical properties may not be corrosion resistant. In other cases, the locations that are susceptible to corrosion are hard to reach. In this thesis, corrosion sensors are discussed that can monitor both the occurrence and the rate of corrosion of metal films, in fully exposed or remote locations. Two corrosion sensors, the fiber optic micromirror and the multiple microline electrodes, are developed and applied in corrosion studies. The fiber optic micromirror sensor is an optical fiber which has been coated with a thin metal film at the cleaved end. Incident light from the backside of the film is reflected back and reflectivity changes are related to the physical or chemical changes that occur on the front side of the micromirror. The sensors were used to monitor corrosion rate, anion adsorption, and underpotential deposition on metal surfaces. In corrosion monitoring, the fiber optic micromirror sensor was found to be best suited for uniform corrosion where corrosion products did not accumulate, and for micromirror thinner than 300A. In anion adsorption measurements on gold, the reflectivity of the fiber optic micromirror decreased as a result of covalent bonding between the adsorbates and the micromirror. The outermost layer of gold acted as if it had lost its metallic character. In underpotential deposition of copper on gold, the reflectivity of the fiber optic micromirror increased. This was attributed to the physical addition of a metal monolayer to the micromirror. The multiple microline electrode (MLE) was used to make electrochemical measurements in thin electrolyte layers to simulate atmospheric corrosion. The individual electrodes from the cross section of a stack of thin films served as working, counter, and reference electrodes, respectively. Although electrochemical measurements were accomplished in electrolyte layers as thin as 10mum with the technique, it was difficult to reduce the electrolyte layer further.

Jin, Wenzhong

1997-11-01

180

Corrosion sensor  

Energy Technology Data Exchange (ETDEWEB)

A corrosion sensor array incorporating individual elements for measuring various elements and ions, such as chloride, sulfide, copper, hydrogen (pH), etc. and elements for evaluating the instantaneous corrosion properties of structural materials. The exact combination and number of elements measured or monitored would depend upon the environmental conditions and materials used which are subject to corrosive effects. Such a corrosion monitoring system embedded in or mounted on a structure exposed to the environment would serve as an early warning system for the onset of severe corrosion problems for the structure, thus providing a safety factor as well as economic factors. The sensor array is accessed to an electronics/computational system, which provides a means for data collection and analysis.

Glass, Robert S. (Livermore, CA); Clarke, Jr., Willis L. (San Ramon, CA); Ciarlo, Dino R. (Livermore, CA)

1994-01-01

 
 
 
 
181

Corrosion sensor  

Energy Technology Data Exchange (ETDEWEB)

A corrosion sensor array is described incorporating individual elements for measuring various elements and ions, such as chloride, sulfide, copper, hydrogen (pH), etc. and elements for evaluating the instantaneous corrosion properties of structural materials. The exact combination and number of elements measured or monitored would depend upon the environmental conditions and materials used which are subject to corrosive effects. Such a corrosion monitoring system embedded in or mounted on a structure exposed to the environment would serve as an early warning system for the onset of severe corrosion problems for the structure, thus providing a safety factor as well as economic factors. The sensor array is accessed to an electronics/computational system, which provides a means for data collection and analysis. 7 figures.

Glass, R.S.; Clarke, W.L. Jr.; Ciarlo, D.R.

1994-04-26

182

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

2011-01-01

183

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; L.A. Dobrza?sk

2013-01-01

184

The ancient Chinese casting techniques  

Directory of Open Access Journals (Sweden)

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

Tan Derui; Lian Haiping

2011-01-01

185

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

2013-01-01

186

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

UK PubMed Central (United Kingdom)

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

Chung WS; Yu MJ; Lee HD

2004-01-01

187

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

Science.gov (United States)

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

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

2004-01-01

188

Clean Metal Casting  

Energy Technology Data Exchange (ETDEWEB)

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.

Makhlouf M. Makhlouf; Diran Apelian

2002-02-05

189

Clean Metal Casting; FINAL  

International Nuclear Information System (INIS)

[en] 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

2002-01-01

190

Vascular Depression  

Directory of Open Access Journals (Sweden)

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

Yunus Emre Sönmez; ?. Özlem Erden Ak?

2013-01-01

191

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

192

Method of casting aerogels  

Energy Technology Data Exchange (ETDEWEB)

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

Poco, John F. (Livermore, CA)

1993-01-01

193

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

194

(Continuous casting 1985)  

Energy Technology Data Exchange (ETDEWEB)

The report covers the Continuous Casting '85 Conference including informal discussions with conference attendees. In general, the papers presented at the conference concerned an overview of continuous steel casting worldwide, state-of-the-art aspects of steel continuous casting technology including caster startup problems, modifications, control system strategies, energy use profiles, quality control aspects, steel chemistry control, refractories, operational aspects of continuous casters, etc. No papers were presented in the development of thin section or thin strip casting of steel. Informal discussions were held with several conference attendees including (1) Bernard Trentini, Executive Director of the Association Technique De La Siderurgie Francaise in Paris, France (similar to the American Iron and Steel Institute); (2) Dr. Wolfgang Reichelt and Dr. Peter Voss-Spilker both of Mannesmann Demag Huttentechnik -a continuous casting and other steel making machine builder in-lieu of meeting at their plant in Duisburg, FRG on May 31; (3) Ewan C. Hewitt of Devote McKee Corp., Sheffield, England; (4) Wilfried Heinemann, head of R D Dept. at Concast Standard AG in Zurich, Switzerland; and (5) Hideo Ueno, engineer of melting section, Mitsubishi Steel Mfg. Co. Ltd, Tokyo Japan. A visit was made to the Teesside Laboratories of British Steel Corp. for discussions of their thin section casting research program in particular and R D program in general.

Wilde, R.A.

1985-06-12

195

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; S. Tenerowicz; T. Wróbel

2008-01-01

196

Seal welded cast iron nuclear waste container  

Energy Technology Data Exchange (ETDEWEB)

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

197

External volume expansion increases subcutaneous thickness, cell proliferation, and vascular remodeling in a murine model.  

UK PubMed Central (United Kingdom)

BACKGROUND: Fat grafting is a powerful tool for soft-tissue reconstruction; however, the science behind recipient bed preparation has not been thoroughly explored. External volume expansion using suction before fat grafting has been used clinically to improve reliability and consistency of graft survival. The authors developed a murine model to investigate the underlying mechanism of external volume expansion. METHODS: The authors created an external volume expansion device using a soft-silicone dome connected to a vacuum source (25 mmHg) to treat the dorsum of mice, and the response was compared with treatment with an occlusive dressing. Treated areas were monitored with magnetic resonance imaging. Remodeling of microvasculature was studied with corrosion casting on day 7. Effects on tissue thickness, number of adipocytes, cell proliferation, and blood vessel density were analyzed at 28 days. RESULTS: Macroscopic analysis showed tissue swelling at sites treated with the external volume expansion device by 21 days, without skin damage. On day 28, external volume expansion increased the thickness of the subcutaneous fat layer twofold, consistent with magnetic resonance imaging observations. The proliferation rate in the subcutaneous layer of expansion-treated areas increased twofold, with a net 2.2-fold increase in number of adipocytes in columns; remodeling of the vessels network occurred, with reorientation and increase of vessel diameters shown by corrosion casting and 1.9-fold augmentation of vessels density. CONCLUSIONS: External volume expansion applied to mouse integument induces highly proliferative and vascularized subcutaneous tissue. Recipient-site preparation using external volume expansion devices may be a promising tool to enhance cell and tissue engraftment.

Heit YI; Lancerotto L; Mesteri I; Ackermann M; Navarrete MF; Nguyen CT; Mukundan S Jr; Konerding MA; Del Vecchio DA; Orgill DP

2012-09-01

198

Development of the Ono continuous casting process; Satetsu ga hagukunda watashi no michi  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the lecture on solidification of metals, in particular, development of OCC (Ono continuous casting) process. Removal of defects during casting is necessary to obtain fatigue or corrosion resistant materials. As molds are cooled from the outside, casting defects are formed by segregation of impurities in the center of castings because of crystal growth from the periphery of castings. In OCC process, on the contrary molds are heated at temperature over freezing points of metals. Castings are cooled in the outside of molds while pulling ingots continuously out of molds. Since ingots are, on the contrary, solidified from its center toward its periphery, the metal structure superior in mechanical property without any casting defect and crystalline grain boundary is obtained. Because of no friction between molds and ingots, smooth fine surfaces of castings are also obtained. OCC process can realize a continuous casting process demonstrating remarkable merits such as labor and energy saving. OCC process also can be applied to continuous strip casting, producing single crystal or uni-directional crystal strips. 4 refs., 20 figs.

Ono, A. [Chiba Institute of Technology, Chiba (Japan)

1995-12-31

199

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

Energy Technology Data Exchange (ETDEWEB)

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

Madhav Rao Gonvindaraju

1999-10-18

200

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 all...

Chaturvedi T

 
 
 
 
201

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Corrosion of water and gas pipes is not desirable from the view point of health, economy and nuisances. There are many factors in soil which attack the metal pipes for corrosion. (Steel, Cast, Iron and Like). That is why the designer of metal pipes for conveyance of metal pipes for conveyance of wat...

M.Razeghi; Jamshidnia; Behnoud

202

Investment casting compound and fine-investment casting compound  

UK PubMed Central (United Kingdom)

The invention relates to a investment casting compound for making casting moulds for alloy castings, especially in dental engineering, with the MgO/SiO2/P2O5 ceramic system, and to a fine-investment casting compound for making casting moulds for alloy castings, especially in dental engineering, with ceramic constituents as a thin coating for the model of the alloy casting to be cast, the coating serving as a primary layer for the further application of an ordinary investment casting compound as secondary layer for making the final casting mould. To provide investment compounds, with which casting moulds can be made which make alloy castings with low surface roughness possible, the addition of a substance is proposed which increases the liquidus temperatures of the ceramic system and reduces the high-temperature oxidation of the alloy casting. This substance can be zirconium silicate (ZrSiO4) and/or a titanium(IV) oxide (TiO2 (anatase and/or rutile)).

GRILL GUENTHER; NOWACK NORBERT PROF DR ING

203

Streptococcus mutans attachment on a cast titanium surface  

Scientific Electronic Library Online (English)

Full Text Available 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 rug (more) osimeter 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.

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

2009-03-01

204

Invisible macrodefects in castings  

International Nuclear Information System (INIS)

[en] There is a wide spectrum of controls which are required to be in place to ensure the maintenance of quality in castings. Most of these are well known, and are not therefore considered in this paper. The parameters which are often overlooked, and thus not controlled, are (i) the rate of flow of liquid metal in the mould to avoid surface turbulence and the generation of macroscopic crack-like defects as a result of folded-in surface films; and (ii) the rate of quench following solution heat treatment. As a result of failure to control these critical parameters castings traditionally exhibit random failure from leakage, and mechanical failure, especially fatigue. Mechanical failure is enhanced by internal stress which is superimposed on service stress to promote premature failure. It is considered that these are the main reasons why in the past castings have been found to be unreliable, compared to other production techniques such as forging. Techniques to control both surface turbulence and internal stresses include respectively (i) the limiting of flow velocities in moulds to less than 0.5 m/s, and (ii) eliminating the water quench from casting heat treatments. These actions are expected to revolutionise the concept of castings as totally reliable products. (orig.)

1993-01-01

205

Invisible macrodefects in castings  

Energy Technology Data Exchange (ETDEWEB)

There is a wide spectrum of controls which are required to be in place to ensure the maintenance of quality in castings. Most of these are well known, and are not therefore considered in this paper. The parameters which are often overlooked, and thus not controlled, are (i) the rate of flow of liquid metal in the mould to avoid surface turbulence and the generation of macroscopic crack-like defects as a result of folded-in surface films; and (ii) the rate of quench following solution heat treatment. As a result of failure to control these critical parameters castings traditionally exhibit random failure from leakage, and mechanical failure, especially fatigue. Mechanical failure is enhanced by internal stress which is superimposed on service stress to promote premature failure. It is considered that these are the main reasons why in the past castings have been found to be unreliable, compared to other production techniques such as forging. Techniques to control both surface turbulence and internal stresses include respectively (i) the limiting of flow velocities in moulds to less than 0.5 m/s, and (ii) eliminating the water quench from casting heat treatments. These actions are expected to revolutionise the concept of castings as totally reliable products. (orig.).

Campbell, J. (Univ. of Birmingham (United Kingdom))

1993-11-01

206

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

UK PubMed Central (United Kingdom)

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.

Finkenstadt VL; Côté GL; Willett JL

2011-06-01

207

The effect of urea on the corrosion behavior of different dental alloys.  

UK PubMed Central (United Kingdom)

OBJECTIVE: Intraoral corrosion of dental alloys has biological, functional, and esthetic consequences. Since it is well known that the salivary urea concentrations undergo changes with various diseases, the present study was undertaken to determine the effect of salivary urea concentrations on the corrosion behavior of commonly used dental casting alloys. MATERIALS AND METHODS: Three casting alloys were subjected to polarization scans in synthetic saliva with three different urea concentrations. RESULTS: Cyclic polarization clearly showed that urea levels above 20 mg/100 ml decreased corrosion current densities, increased the corrosion potentials and, at much higher urea levels, the breakdown potentials. CONCLUSION: The data indicate that elevated urea levels reduced the corrosion susceptibility of all alloys, possibly through adsorption of organics onto the metal surface. This study indicates that corrosion testing performed in sterile saline or synthetic saliva without organic components could be misleading.

Geckili O; Bilhan H; Bilgin T; Anthony von Fraunhofer J

2012-01-01

208

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

UK PubMed Central (United Kingdom)

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.

Finkenstadt VictoriaL; Co?te? GregoryL; Willett JL

2011-06-01

209

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

2011-02-03

210

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

UK PubMed Central (United Kingdom)

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

Reddy SS; Revathi K; Reddy SK

2013-07-01

211

Cast Heatsink Design Advantages  

UK PubMed Central (United Kingdom)

:Power dissipation of chips has been raising faster thanthe technology needed to economically cool them.Especially in the high performance arena. To get highefficiency heatsinks presently, extrusions are machined orentire heatsinks are machined with strategically arrangedfins. These methods are not as effective in highcomponent densities or cost sensitive units compared tonewer, porosity free castings.Die casting of, low cost materials, especially aluminumdoped zinc, creates a porosity free, low cost, efficientheatsink. Hand poured aluminum and brass alloys are alsouseful in special circumstances, but with a cost penalty.Airfoil shapes can be made to take full advantage of true3D casting shapes and direct the airflow as required; thiscan greatly reduce back pressure by creating turbulenceonly where needed. Assembly clues such as arrows can belocated along with stops and alignment pins. Eventurbulence enhancing grooves and attachment points canbe added with little p...

Kurtis P. Keller

212

Metal Corrosion  

Science.gov (United States)

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

Stoebe, Thomas G.

2011-09-22

213

Casting Characteristics of Aluminum Die Casting Alloys  

Energy Technology Data Exchange (ETDEWEB)

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

Makhlouf M. Makhlouf; Diran Apelian

2002-02-05

214

Investment Casting of Columbium Alloys.  

Science.gov (United States)

The state of the art of columbium alloy investment castings has been advanced. In addition to demonstration of castability of four different alloys, the cast material itself has been characterized with respect to microstructure, alloy segregation, weldabi...

J. R. Humphrey A. I. Niravath

1975-01-01

215

Investment casting method and apparatus  

UK PubMed Central (United Kingdom)

A modified investment casting process is effective to more safely and efficiently produce cast articles. The casting process utilizes a solid, rigid riser tube, in place of a wax tree, upon which heat disposable, positive models of an article to be cast are joined. This assembly is coated with a refractory and after drying of the refractory the heat disposable positive models are removed. Thereafter the ceramic shell is heated and fired and molten casting material is poured into the assembly. The molten casting material flows from the riser tube to fill the cavities formerly occupied by the positive models. Upon cooling and solidification of the casting material, the refractory is fractured and cast parts are removed.

Hoherchak Joseph M.

216

The Development of Corrosion Resistant Zirconium Alloy  

International Nuclear Information System (INIS)

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

2000-01-01

217

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; Tomasz Ta?ski; Szymon Malara

2011-01-01

218

Vascular calcification.  

UK PubMed Central (United Kingdom)

PURPOSE OF REVIEW: This review presents new evidence related to molecular mechanisms involved in the process of cardiovascular calcification, as well as to discuss new biomarkers and novel therapeutic strategies related to vascular calcification in chronic kidney disease (CKD) patients. RECENT FINDINGS: microRNAs have emerged as potential players in the genesis of osteo-chondrogenic transformation, depending on the stimulus and the localization of vascular calcification. The disturbances of the fibroblast growth factor-23 (FGF23)/alpha-Klotho (Klotho) axis observed in CKD appear to play an important role in CKD-associated vascular calcification. Numerous studies have identified circulating biomarkers potentially responsible for vascular calcification and have evaluated their link with this process. The respective role of these biomarkers is not yet elucidated. Beyond phosphate binders, modulation of calcium-sensing receptor and vitamin K supplementation come into sight as new potential strategies to prevent cardiovascular calcification. CONCLUSION: A better understanding of the molecular mechanisms which are responsible for cardiovascular calcification have led to a better detection and more adequate follow-up of this pathologic process, as well as the identification of novel therapeutic targets. Whether these new insights will lead to improved care and better survival of CKD patients with cardiovascular calcification remains to be demonstrated.

Massy ZA; Drüeke TB

2013-07-01

219

Characterization of Al-Mn particles in AZ91D investment castings  

International Nuclear Information System (INIS)

[en] 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

2007-01-01

220

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; J. Kasi?ska

2012-01-01

 
 
 
 
221

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

222

Corrosion inhibitors  

Energy Technology Data Exchange (ETDEWEB)

This invention relates to a composition comprising (1) an alkenyl or alkyl succinic acid or the anhydride thereof; and (2) a triester of about 3 moles of an alkenyl or alkyl succinic acid or the anhydride thereof and about 1 mole of a trialkanolamine; and to the use thereof as a corrosion inhibitor.

Godar, R.L.; Hendricks, C.C.; Roux, K.R.

1981-03-03

223

Atmospheric corrosion.  

Science.gov (United States)

A model of electrolytic corrosion is developed. It is shown that electrically conducting channels threading through the oxide layer and connecting anodic and cathodic areas, obey the equation for a reactant being catalyzed by its product. The resulting autocatalytic equation is compared with available experimental data and found to be widely applicable and capable of unifying many experimental observations. PMID:16592135

Eyring, H; Robertson, B; Chu, C C; Andersen, T

1974-02-01

224

Atmospheric corrosion.  

UK PubMed Central (United Kingdom)

A model of electrolytic corrosion is developed. It is shown that electrically conducting channels threading through the oxide layer and connecting anodic and cathodic areas, obey the equation for a reactant being catalyzed by its product. The resulting autocatalytic equation is compared with available experimental data and found to be widely applicable and capable of unifying many experimental observations.

Eyring H; Robertson B; Chu CC; Andersen T

1974-02-01

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; G. Gumienny

2008-01-01

226

Extrusion cast explosive  

Energy Technology Data Exchange (ETDEWEB)

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

Scribner, Kenneth J. (Livermore, CA)

1985-01-01

227

Polycrystal silicon semiconductor casting  

Energy Technology Data Exchange (ETDEWEB)

A commonly used silicon casting is to melt solid silicon in a silica crucible inside a heating furnace and cast it into a graphite mold. Recently coupling of O/sub 2/ and N/sub 2/ gases with silicon is prevented by melting solid silicon in vacuum or in inactive gas. According to the processes of West German and American companies, a container in which silicon melts is made of silica, consequently is easy to be worn and according to the processes of a French company and the same American company as above, they take time and their productivity per furnace declines since melting and solidification of the raw material are done in the same crucible using the same heat source. In order to solve the above problems, in this invention, continuous casting is conducted without generating adhesives of silicon oxide or nitride and dust by casting silicon in high vacuum, then in the first process, solid silicon is directly melt in the mold with an electron beam gun or in the second process, solid silicon is melt by the heat source of an electron beam gun on an unwearing water cooled hearth. Thus this invention offers in either way above the process appropriate for mass production of polycrystal silicon semiconductor ingots at low cost. (3 figs)

Shiraiwa, Toshio; Kaneko, Kyojiro

1987-11-13

228

Clad Cast Steel Strip.  

Science.gov (United States)

A process for producing continuous cast hot band crystalline metal strips comprising feeding thin gauge metal strips and molten metal into a gap formed between opposed quenching surfaces. The film of molten metal is cooled while in contact with the quench...

R. L. Sheneman

1983-01-01

229

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; M. Stawarz; T. Wróbel; W. Sebzda; B. Grzesik; M. St?pie?

2010-01-01

230

Computer cast blast modelling  

Energy Technology Data Exchange (ETDEWEB)

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

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

1994-07-01

231

Management of Corrosion  

Energy Technology Data Exchange (ETDEWEB)

Papers submitted for AGARD Lecture Series No. 141 (Management of Corrosion), concerning the management of corrosion in the aerospace field, are presented. Among the subjects covered are the superiority of corrosion resistance of low alloy steel containing 0.5 wt% copper over plain carbon steel, some theoretical aspects of corrosion and practical implications for aircraft, the effect of the microenvironment on corrosion, corrosion protection by means of various coatings, the special susceptibility of aircraft components to corrosion, aircraft corrosion preventive measures, experimental methods used to monitor corrosion, and the effect of road salt and a marine environment on thin-gage metals used in vehicle and aircraft manufacture.

1985-05-01

232

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

1990-01-01

233

High strength corrosion-resistant zirconium aluminum alloys  

International Nuclear Information System (INIS)

[en] A zirconium-aluminum alloy is described possessing superior corrosion resistance and mechanical properties. This alloy, preferably 7.5-9.5 wt% aluminum, is cast, worked in the Zr(Al)-Zr2Al region, and annealed to a substantially continuous matrix of Zr3Al. (E.C.B.)

1976-01-01

234

Bulk metallic glass tube casting  

Energy Technology Data Exchange (ETDEWEB)

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

Soinila, E., E-mail: Erno.Soinila@hut.fi; Antin, K.; Bossuyt, S.; Haenninen, H.

2011-06-15

235

Precision cast vs. wrought superalloys  

Energy Technology Data Exchange (ETDEWEB)

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. 25 references.

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

1986-12-01

236

Color Casts Detection and Adjustment  

Directory of Open Access Journals (Sweden)

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

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

2011-01-01

237

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; M. Perzyk

2011-01-01

238

Cast iron - a predictable material  

Directory of Open Access Journals (Sweden)

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

Jorg C. Sturm; Guido Busch

2011-01-01

239

Corrosion Doctors  

Science.gov (United States)

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

Doctors, Corrosion

240

Volume MLS ray casting.  

Science.gov (United States)

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 effects. We also present a novel, adaptive preintegration scheme to improve the efficiency of the ray casting algorithm by reducing the overall number of function evaluations, and an efficient implementation of our framework exploiting modern graphics hardware. The resulting system enables high-quality volume integration and shaded isosurface rendering for regular and irregular volume data. PMID:18988986

Ledergerber, Christian; Guennebaud, Gaël; Meyer, Miriah; Bächer, Moritz; Pfister, Hanspeter

 
 
 
 
241

Volume MLS ray casting.  

UK PubMed Central (United Kingdom)

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 effects. We also present a novel, adaptive preintegration scheme to improve the efficiency of the ray casting algorithm by reducing the overall number of function evaluations, and an efficient implementation of our framework exploiting modern graphics hardware. The resulting system enables high-quality volume integration and shaded isosurface rendering for regular and irregular volume data.

Ledergerber C; Guennebaud G; Meyer M; Bächer M; Pfister H

2008-11-01

242

Computer cast blast modelling  

Energy Technology Data Exchange (ETDEWEB)

Cast blasting can be designed to utilize explosive energy effectively and economically for coal mining operations to remove overburden material. This paper compares two blast models known as DMC (Distinct Motion Code) and SABREX (Scientific Approach to Breaking Rock with Explosives). DMC applies discrete spherical elements interacted with the flow of explosive gases and the explicit time integration to track particle motion resulting from a blast. The input to this model includes multi-layer rock properties, and both loading geometry and explosives equation-of-state parameters. It enables the user to have a wide range of control over drill pattern and explosive loading design parameters. SABREX assumes that heave process is controlled by the explosive gases which determines the velocity and time of initial movement of blocks within the burden, and then tracks the motion of the blocks until they come to a rest. In order to reduce computing time, the in-flight collisions of blocks are not considered and the motion of the first row is made to limit the motion of subsequent rows. Although modelling a blast is a complex task, the advance in computer technology has increased the computing power of small work stations as well as PC (personal computers) to permit a much shorter turn-around time for complex computations. The DMC can perform a blast simulation in 0.5 hours on the SUN SPARC station 10-41 while the new SABREX 3.5 produces results of a cast blast in ten seconds on a 486-PC. Predicted percentage of cast and face velocities from both computer codes compare well with the measured results from a full scale cast blast.

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

1994-12-31

243

Metal casting extended assessments  

Energy Technology Data Exchange (ETDEWEB)

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.

Ambs, L.; Kosanovic, D.; Muller, M.; Kasten, D.

1999-07-01

244

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.

1999-01-01

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 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.

1994-03-04

246

Corrosion source book  

Energy Technology Data Exchange (ETDEWEB)

This book presents a collection of articles designed to inform engineers, metallurgists, and designers of the nature of corrosion and the means of prevention. The principles of corrosion technology are presented in the 80 articles contained in this collection of technical papers published in ASM and NACE. Beginning with eight visual forms of corrosion and discussions of the primary sources of corrosion, attention is given to protective coatings, corrosion of specific alloys, stress corrosion cracking, and special topics in corrosion engineering. Sections include: Protection Against Corrosion; Specific Alloys; Coatings; Cracking; Special Topics.

Coburn, S.K.

1984-01-01

247

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; M. Cholewa; S. Tenerowicz

2011-01-01

248

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.

Ji Qing; Wu Chunmiao

2012-01-01

249

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

250

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.

J. Konieczny; K. Labisz; J. Wieczorek; L.A. Dobrza?ski

2008-01-01

251

Effect of heat treatment on corrosion resistance of WE54 alloy  

Directory of Open Access Journals (Sweden)

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

T. Rzycho?; J. Michalska; A. Kie?bus

2007-01-01

252

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; I. Duplan?i?; B. Lela

2010-01-01

253

Synergistic effect of cavitation erosion and corrosion of various engineering alloys in 3.5% NaCl solution  

Energy Technology Data Exchange (ETDEWEB)

The cavitation erosion and corrosion characteristics of various engineering alloys including grey cast iron, steels, copper-based alloys and stainless steels were studied by means of a 20 kHz ultrasonic vibrator at a peak-to-peak amplitude of 30 {mu}m in distilled water and in 3.5% NaCl solution at 23 C. The contributions of pure mechanical erosion, electrochemical corrosion, and the synergism between erosion and corrosion to the overall cavitation erosion-corrosion in 3.5% NaCl solution were determined. It was found that in 3.5% NaCl solution, the effect of corrosion on the overall cavitation erosion-corrosion was most pronounced in mild steel and grey cast iron, and negligible in stainless steels. The stainless steels only suffered pure mechanical erosion in 3.5% NaCl solution in the presence of cavitation owing to the unfavourable local environment for pit growth. (orig.)

Kwok, C.T.; Cheng, F.T. [Hong Kong Polytechnic, Kowloon (Hong Kong). Dept. of Applied Physiscs; Man, H.C. [Department of Manufacturing Engineering, The Hong Kong Polytechnic University, Hung Hom,, Hong Kong, Kowloon (China)

2000-10-15

254

Modeling of alloy casting solidification  

Science.gov (United States)

Alloy casting solidification processes involve many physical phenomena such as chemistry variation, phase transformation, heat transfer, fluid flow, microstructure evolution, and mechanical stress.1 Simulation technologies are applied extensively in casting industries to understand the effects of these phenomena on the formation of defects and on the final mechanical properties of the castings. As of today, defect prediction is still one of the main purposes for casting solidification simulation. In this paper, we will first present the commonly used microstructure simulation methods, then discuss the predictions of the major defects of a casting, such as porosity, hot tearing, and macrosegregation. The modeling of casting solidification can be chained with later stages of heat treatment such that the resultant microstructure, defects, and mechanical state will be used as the initial conditions of the subsequent processes, ensuring the tracking of the component history and maintaining a high level of accuracy across metallurgical stages.

Guo, Jianzheng; Samonds, Mark

2011-07-01

255

Efficacy of patient information concerning casts applied post-fracture.  

UK PubMed Central (United Kingdom)

INTRODUCTION: Serious complications can result when casts are used for bone immobilization following fracture. Adequate patient information regarding cast care and possible complications is vital for prevention. This study examines the effectiveness of verbal and written patient information regarding cast safety. METHODS: Patients (n= 109; age ?18 years) from three Western Australian teaching hospitals were interviewed using a custom-designed questionnaire. Patients' understanding of cast care and possible complications were tested by recall of seven categories of information, notably: pain, swelling, cast care, itching, neural signs, vascular signs/symptoms, exercise/rest. A follow-up phone call (3-8 weeks after initial interview) was conducted to elicit complications and determine information recall. RESULTS: Written information was received by 62% of patients; however, overall, only 35% claimed to have read the information provided. Of these, the highest recall was in four of seven information categories. A high proportion of those given only verbal information had poor recall (?2 categories, defined a priori). In contrast, patients who also received written information had better recall (three or more categories, defined a priori, P= 0.031). Four of the 109 patients developed complications attributable to the cast (three had pressure ulcers and one had a deep vein thrombosis). CONCLUSION: Patient recall of information concerning cast care and possible complications was no more than 60%. The provision of written information was associated with a significantly higher awareness of possible complications. The results indicate that for fracture care, the delivery and use of information protocols can be greatly improved.

Hossieny P; Carey Smith R; Yates P; Carroll G

2012-03-01

256

CAST PELLETS FOR PLANTING SEEDS  

UK PubMed Central (United Kingdom)

A multi-plant product and a method of producing a container of plants are described. Cast pellets containing plant seeds selected for their seed germination timing are planted in a container with a vegetative cutting. The cutting can be selected for having root initiation timing synchronized with the seed germination timing of the plant seeds in the cast pellet. The seed germination timing of the plant seeds can be modified by selecting the volume of the cast pellet.

CONRAD ROBERT

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

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

259

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

UK PubMed Central (United Kingdom)

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 TP

2009-01-01

260

Ceramic linings beat coal plant's abrasion/corrosion problems  

Energy Technology Data Exchange (ETDEWEB)

A combination of erosion and corrosion at the Victoria Junction coal preparation plant in Sydney, Nova Scotia was causing serious problems. Schedule 80 mild steel pipes were starting to fail as well as some quarter-inch steel plates in the lauders and chutes. Some corrosion tests were carried out and the high chloride level in the process water was felt to be the single most important contribution to the corrosion problem. Cast basalt was selected as a solution to the pipe wear problem. Three different types of abrasion/corrosion-resistant tiling - basalt tiles, kalceram tiles and ceramic tiles were well suited to the chloride conditions at this plant.

1985-07-01

 
 
 
 
261

Casting mould comprising a photopolymer  

UK PubMed Central (United Kingdom)

A method of casting a product comprises creating a finished photopolymer mould, introducing liquid into the mould, hardening the liquid and removing the photopolymer mould. Removal may be conventional or comprise destroying the mould by burning or dissolving the. The mould may comprise a photopolymer plate attached to a formwork and treated with release agent or a heat resistant material prior to casting. The mould may be used to cast a refractory mould used to cast a secondary product comprising glass metal or ceramics. The mould may be used to cast concrete, glass, gels, metal, polymer, plaster and foodstuffs such as high-resolution embossed icing on a cake. A design having line work or halftones by way of recesses in the photopolymer can produce a cast product with tonal variations. During production one or both sides of a photopolymer plate may be exposed to light through a mask comprising a filter which permits variable intensity of light to reach the photopolymer. The mould may be used to cast company logos into walls of buildings. Items such as reflectors or precious or semi-precious stones may be placed in the photopolymer prior to casting to incorporate them into the cast article.

DALE ANDREW MARK; BARRETT ERIC

262

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; J. Szajnar; T. Szuter

2013-01-01

263

Geothermal corrosivity classification system  

Energy Technology Data Exchange (ETDEWEB)

A Geothermal Corrosivity Classification System, based on corrosion experience at more than 45 geothermal resources worldwide, is presented. This system divides geothermal resources into six classes based on fluid chemistry and corrosiveness to carbon steel and other materials. The system is expected to facilitate corrosion engineering decision-making and reduce the cost of geothermal systems.

Ellis, P.F. II

1981-10-01

264

Towards Corrosion Detection System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Corrosion is a natural process that seeks to reduce the binding energy in metals. The end result of corrosion involves a metal atom being oxidized. Surface corrosion on aluminum aircraft skins, near joints and around fasteners, is often an indicator of buried structural corrosion and cracking In th...

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

265

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; T. Chairuangsri; A. Wiengmoon

2007-01-01

266

Phase Transformations in Cast Duplex Stainless Steels  

Energy Technology Data Exchange (ETDEWEB)

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

Yoon-Jun Kim

2004-12-19

267

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

2011-01-01

268

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

2011-01-01

269

USAMP Magnesium Powertrain Cast Components: Fundamental research summary  

Science.gov (United States)

The Magnesium Powertrain Cast Components (MPCC) Project is an effort, jointly sponsored by the U.S. Department of Energy and the U.S. Automotive Materials Partnership (USAMP), to demonstrate the readiness of magnesium for use in powertrain applications by testing a set the magnesium-intensive engines which were designed, cast, and assembled. A second MPCC goal is to promote new and strengthen existing magnesium scientific research in North America. The project investigated several of the newly developed high-temperature (creep-resistant) magnesium alloys, which will potentially experience service conditions in the temperature range of 150-200°C and about 50-110 MPa in stresses (typical powertrain). However, the mechanical and physical behaviors of these new alloys are not fully understood. This article outlines MPCC-supported fundamental scientific research into the workings of these new alloys. The areas of research are: phase equilibrium and computational thermodynamics, creep deformation mechanisms, corrosion, hot tearing, and alloy recycling.

Beals, Randy S.; Liu, Zi-Kui; Wayne Jones, J.; Mallick, P. K.; Emadi, Daryoush; Schwam, David; Powell, Bob R.

2007-08-01

270

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

Directory of Open Access Journals (Sweden)

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

T. Ta?ski; K. Labisz; L.A. Dobrza?ski

2011-01-01

271

Prototype casting fabrication by stereolithography  

Energy Technology Data Exchange (ETDEWEB)

The evolution of the new technology of producing CAD models by ultraviolet solidification of resin materials (``STEREOLITHOGRAPHY``) continues to progress. The potential application area of rigid fabrication of prototype investment castings is becoming more feasible as we continue to successfully yield experimental castings by the ``SHELL`` processing method. This supplemental (to 11/90 publication) report briefly reviews the original project objectives, activities related to these objectives since November 1990, and progress made through December 1991. We discuss several new case studies involving new resin materials (and other materials) tested along with investment casting processing results. The most recent success, the processing of the highly complex ``C`` HOUSING design by the ``shell`` mold process in both aluminum and steel, will be discussed. This is considered a major breakthrough toward establishing this new technology as a viable approach to the rapid development of prototype investment castings, employing the most common aerospace (precision) cast process. Our future planning calls for expanding the study to help the investment casting industry in refining related processing techniques and to continue our evaluation of new resins suitable for the casting process. Present project planning calls for the completion of this study by the third quarter FY93 or sooner. We believe that with the continued excellent cooperation of our casting supplier study team and an accelerated effort by resin materials producers to further refine related materials, we can achieve all objectives during the planned time frame.

Cromwell, W.E.

1992-03-01

272

Prototype casting fabrication by stereolithography  

Energy Technology Data Exchange (ETDEWEB)

The evolution of the new technology of producing CAD models by ultraviolet solidification of resin materials ( STEREOLITHOGRAPHY'') continues to progress. The potential application area of rigid fabrication of prototype investment castings is becoming more feasible as we continue to successfully yield experimental castings by the SHELL'' processing method. This supplemental (to 11/90 publication) report briefly reviews the original project objectives, activities related to these objectives since November 1990, and progress made through December 1991. We discuss several new case studies involving new resin materials (and other materials) tested along with investment casting processing results. The most recent success, the processing of the highly complex C'' HOUSING design by the shell'' mold process in both aluminum and steel, will be discussed. This is considered a major breakthrough toward establishing this new technology as a viable approach to the rapid development of prototype investment castings, employing the most common aerospace (precision) cast process. Our future planning calls for expanding the study to help the investment casting industry in refining related processing techniques and to continue our evaluation of new resins suitable for the casting process. Present project planning calls for the completion of this study by the third quarter FY93 or sooner. We believe that with the continued excellent cooperation of our casting supplier study team and an accelerated effort by resin materials producers to further refine related materials, we can achieve all objectives during the planned time frame.

Cromwell, W.E.

1992-03-01

273

Lost-Soap Aluminum Casting.  

Science.gov (United States)

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

Mihalow, Paula

1980-01-01

274

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

2009-01-01

275

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.

1976-01-01

276

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

277

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

International Nuclear Information System (INIS)

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

278

Ohno continuous casting  

Energy Technology Data Exchange (ETDEWEB)

Production of net-shape products directly from the liquid is an attractive manufacturing route for alloys that are difficult to process or that cannot be rolled, drawn, or extruded. Developed at the Chiba Institute of Technology in Japan, the Ohno Continuous Casting (OCC) approach not only provides significant cost savings, but also has the potential to create new products. OCC process equipment includes a melting furnace, crucible, mold level-control block, cooling device, and pinch rolls. OCC is currently used to produce copper rods and wires for audio and video cables, and aluminum alloy welding rods for hard-surfacing applications. For example, Mitsui Engineering and Ship Building Co. has used OCC to produce copper tubing products with internal fins and partitions for applications such as heat exchanger tubes and induction coils.

Soda, H.; McLean, A. [Univ. of Toronto, Ontario (Canada); Motoyasu, G.; Ohno, A. [Chiba Institute of Technology (Japan)

1995-04-01

279

Al - BASED CAST COMPOSITES  

Directory of Open Access Journals (Sweden)

Full Text Available The economy is very important feature nowadays in themarket. The researches are playing an important role inengineering field to increase the life of machine parts /components and decrease the cost. The compositematerials have the potential to replace widely used steeland aluminium due to their good characteristics withbetter performance. The Al-based composites have foundextensive applications in automobile industries andaerospace industries due to their increased stiffness,strength, thermal conductivity and wear resistanceproperties. A number of particulate phases have beenemployed in the Al-alloy matrix. The cast aluminiumceramicparticulate composites are finding applications inpistons, connecting rods, cylinder liner, engine cylinderblock, electrical contacts etc.The present investigation isbased on study of the effect of particulate phase on theSEM study, micro-hardness, elastic modulus, tensilestrength and the wear behaviour of Al-5 % SiC-7 % Fe,Al-10 % SiC-6 % Fe and Al-15 % SiC-5 % Fe composites.

Rakesh Kumar Yadav; Ashu Yadav

2011-01-01

280

Electronic casting brake  

UK PubMed Central (United Kingdom)

A casting reel (10) has a reel housing (22). A reel spool shaft (14) is rotatably mounted in the reel housing. A magnetic disc (12) is connected to rotate with the shaft (14). An electrical coil (20) produces an output signal in response to movement of the disk (12). A control circuit (28) is connected to receive the output signal from the electrical coil (20). The control circuit (28) has a thyristor (52) which produces a drag signal that varies based on the output signal from the electrical coil. The electrical coil and magnetic disk provide a variable drag on the reel spool shaft (14). The variable drag changes based on the drag signal from the thyristor (52).

YOUNG JOHN N

 
 
 
 
281

Corrosion Bulletin Number 2, 1981.  

Science.gov (United States)

Contents: Scientific control of corrosion processes taking place at metal environment interfaces; Corrosion problems in pulp and paper industry; Corrosion behavior of steel reinforcement in different pozzolana cement concretes; Corrosion kinetics and mech...

K. S. Rajagopalan

1981-01-01

282

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 rockted 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.

1991-01-01

283

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.

1982-01-01

284

Zinc-The key to preventing corrosion  

Science.gov (United States)

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

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

2011-01-01

285

Corrosion of container materials under clay repository conditions  

International Nuclear Information System (INIS)

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

1990-01-01

286

In vitro vs in vivo corrosion analyses of two alloys.  

UK PubMed Central (United Kingdom)

The in vitro and in vivo corrosion characteristics of two alloys, cast Co-Cr-Mo (ASTM F75) and wrought Ni-Cr-Mo, were evaluated using electro-chemical corrosion analysis. Two in vitro electrolytic solutions were utilized, an isotonic saline solution consisting of 0.9 w/o NaCl in distilled water and an isotonic saline solution with 10 v/o sterile calf serum. The in vivo environment was created by implanting cylindrically shaped specimens of each alloy into the back muscles of New Zealand white rabbits. Cyclic anodic and cathodic polarization curves were generated for the three test conditions and subsequently were compared. Anodic curves conducted using the isotonic saline and isotonic saline plus serum electrolyte solutions were very similar to the anodic curves generated for the implanted alloy specimens for both alloys. The corrosion rates predicted from the in vitro and in vivo cathodic polarization curves were not statistically different for the three test conditions. Overall, the corrosion data generated using the in vitro environmental conditions adequately predicted the in vivo corrosion behavior of the cast Co-Cr-Mo and wrought Ni-Cr-Mo alloys.

Lucas LC; Dale P; Buchanan R; Gill Y; Griffin D; Lemons JE

1991-01-01

287

Surface Properties and Corrosion Behavior of Co-Cr Alloy Fabricated with Selective Laser Melting Technique.  

UK PubMed Central (United Kingdom)

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.

Xin XZ; Chen J; Xiang N; Wei B

2013-04-01

288

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-12-30

289

Rapid in vitro corrosion induced by crack-like pathway in biodegradable mg-10% ca alloy.  

UK PubMed Central (United Kingdom)

The in vitro corrosion mechanism of the biodegradable cast Mg-10% Ca binary alloy in Hanks' solution was evaluated through transmission electron microscopy observations. The corrosion behavior depends strongly on the microstructural peculiarity of Mg2Ca phase surrounding the island-like primary Mg phase and the fast corrosion induced by the interdiffusion of O and Ca via the Mg2Ca phase of lamellar structure. At the corrosion front, we found that a nanosized crack-like pathway was formed along the interface between the Mg2Ca phase and the primary Mg phase. Through the crack-like pathway, O and Ca are atomically exchanged each other and then the corroded Mg2Ca phase was transformed to Mg oxides. The in vitro corrosion by the exchange of Ca and O at the nanosized pathway led to the rapid bulk corrosion in the Mg-Ca alloys.

Jung JY; Kwon SJ; Han HS; Yang GF; Lee JY; Yang SJ; Cho SY; Cha PR; Kim YY; Kim YC; Seok HK; Ahn JP

2013-08-01

290

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.

2006-12-30

291

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

292

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)

2005-01-01

293

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

294

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

International Nuclear Information System (INIS)

[en] 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

1985-01-01

295

Rapid Manufacturing Via Metal Casting  

Science.gov (United States)

The metal casting industry in undergoing significant changes and it is necessary for manufacturing engineering, industrial engineering and design students to recognize these changes. Rapid manufacturing has the potential to revolutionize the metal casting industry by greatly reducing the tooling requirements necessary to produce components. The lead times to produce complex components are being reduced from months to days. A large reduction in the traditional labor requirements for molders, coremakers, patternmakers, and toolmakers will occur. The numerous advantages of the process are discussed and the major limitations are also presented. The "Third Wave" has arrived in the metal casting industry.

Creese, Robert

2009-07-14

296

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; V Sivakumar

2009-01-01

297

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

Directory of Open Access Journals (Sweden)

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

Tatiana Liptáková; Milan Malcho; Jozef Janda?ka

2010-01-01

298

Corrosion testing of secondary coolants for heat pump systems  

Energy Technology Data Exchange (ETDEWEB)

In this investigation the interest was focused on the corrosivity of secondary coolants based on calcium chloride, ethanol or potassium carbonate. Ethylene glycol was used as a reference solution. Both laboratory and plant tests were performed by using coupons of some common metals immersed in these solutions Evaluation of the coupon-tests was made by visual inspection and weight loss measurements. The results indicated a remaining risk for localized corrosion on carbon steel in brines based on calcium chloride. The general corrosion rate of carbon steel was relatively high in an aqueous solution containing 25% ethanol, because of the fact that the original corrosion inhibitor was excluded from the commercial product as one of the constituents caused foaming in the system. The most promising alternative seemed to be a solution based on potassium carbonate with addition of corrosion inhibitors. In a plant test lasting for a period of one year, the general corrosion rate was determined to be less than 1 mdd (mg/dm/sup 2/ and day) for carbon steel and for grey cast iron. The corrosion rates were also quite negligible for other metals exposed for inhibited potassium carbonate in pilot plant tests.

Berendson, J.

1986-12-15

299

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

Energy Technology Data Exchange (ETDEWEB)

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

Graves, C.E., Fluor Daniel Hanford

1997-03-21

300

Role of vascular endothelial growth factor in the pathophysiology of nonalcoholic steatohepatitis in two rodent models.  

Science.gov (United States)

The pathophysiology of nonalcoholic steatohepatitis (NASH) should be approached as a multifactorial process. In several stages of NASH, a link between disease progression and hepatic microvasculature changes can be made. In this study we investigated the role of angiogenesis in two mouse models for NASH, and the effect of a preventive and therapeutic antiangiogenic treatment in a diet-induced mouse model for NASH. Protein and RNA levels of angiogenic and inflammatory factors were significantly up-regulated in the liver of C56BL/6 and db/db mice with NASH at different timepoints. To examine the effect of angiogenic factors on the disease progression of NASH, a prevention and treatment study was set up, blocking the placental growth factor (PlGF) or vascular endothelial growth factor receptor 2 (VEGFR2). Our study showed that treatment prevents the progression of NASH by attenuating steatosis and inflammation, both in a preventive and therapeutic setting, thereby confirming the hypothesis that angiogenic factors play an early role in the disease progression from steatosis to NASH. Anti-PlGF (?PlGF) did not significantly improve liver histology. Vascular corrosion casting showed a more disrupted liver vasculature in mice with NASH compared to controls. Treatment with ?VEGFR2 showed an improvement of the liver vasculature. Moreover, fat-laden primary hepatocytes treated with ?VEGFR2 stored significantly less lipids. Conclusion: Our results demonstrate that there is an increased expression of angiogenic factors in the liver in different mouse models for NASH. We found that VEGFR2 blockage attenuates steatosis and inflammation in a diet-induced mouse model for NASH in a preventive and therapeutic setting. Our findings warrant further investigation of the role of angiogenesis in the pathophysiology in NASH. PMID:23299577

Coulon, Stephanie; Legry, Vanessa; Heindryckx, Femke; Van Steenkiste, Christophe; Casteleyn, Christophe; Olievier, Kim; Libbrecht, Louis; Carmeliet, Peter; Jonckx, Bart; Stassen, Jean-Marie; Van Vlierberghe, Hans; Leclercq, Isabelle; Colle, Isabelle; Geerts, Anja

2013-03-14

 
 
 
 
301

Role of vascular endothelial growth factor in the pathophysiology of nonalcoholic steatohepatitis in two rodent models.  

UK PubMed Central (United Kingdom)

The pathophysiology of nonalcoholic steatohepatitis (NASH) should be approached as a multifactorial process. In several stages of NASH, a link between disease progression and hepatic microvasculature changes can be made. In this study we investigated the role of angiogenesis in two mouse models for NASH, and the effect of a preventive and therapeutic antiangiogenic treatment in a diet-induced mouse model for NASH. Protein and RNA levels of angiogenic and inflammatory factors were significantly up-regulated in the liver of C56BL/6 and db/db mice with NASH at different timepoints. To examine the effect of angiogenic factors on the disease progression of NASH, a prevention and treatment study was set up, blocking the placental growth factor (PlGF) or vascular endothelial growth factor receptor 2 (VEGFR2). Our study showed that treatment prevents the progression of NASH by attenuating steatosis and inflammation, both in a preventive and therapeutic setting, thereby confirming the hypothesis that angiogenic factors play an early role in the disease progression from steatosis to NASH. Anti-PlGF (?PlGF) did not significantly improve liver histology. Vascular corrosion casting showed a more disrupted liver vasculature in mice with NASH compared to controls. Treatment with ?VEGFR2 showed an improvement of the liver vasculature. Moreover, fat-laden primary hepatocytes treated with ?VEGFR2 stored significantly less lipids. Conclusion: Our results demonstrate that there is an increased expression of angiogenic factors in the liver in different mouse models for NASH. We found that VEGFR2 blockage attenuates steatosis and inflammation in a diet-induced mouse model for NASH in a preventive and therapeutic setting. Our findings warrant further investigation of the role of angiogenesis in the pathophysiology in NASH.

Coulon S; Legry V; Heindryckx F; Van Steenkiste C; Casteleyn C; Olievier K; Libbrecht L; Carmeliet P; Jonckx B; Stassen JM; Van Vlierberghe H; Leclercq I; Colle I; Geerts A

2013-05-01

302

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

Energy Technology Data Exchange (ETDEWEB)

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

Abdel-Rahman, M.; Abd El-Mageed, A.M.; Abu El-Ainin, H.M. [Dept. of Production Engineering and Design, Faculty of Engineering, Minia University, Minia (Egypt)

1999-07-01

303

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

International Nuclear Information System (INIS)

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

1999-01-01

304

Erosion-corrosion.  

Science.gov (United States)

A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction ar...

B. Aghili

1999-01-01

305

Deconstructing the Caste Hegemony: Lambada Oral Literature  

Directory of Open Access Journals (Sweden)

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

Suneetha Rani Karamsi

2010-01-01

306

Investment casting design of experiment. Final report  

Energy Technology Data Exchange (ETDEWEB)

Specific steps in the investment casting process were analyzed in a designed experiment. The casting`s sensitivity to changes in these process steps was experimentally determined Dimensional and radiographic inspection were used to judge the sensitivity of the casting. Thirty-six castings of different pedigrees were poured and measured. Some of the dimensional inspection was conducted during the processing. It was confirmed that wax fixturing, number of gates, gate location, pour and mold temperature, pour speed, and cooling profile all affected the radiographic quality of the casting. Gate and runner assembly techniques, number of gates, and mold temperature affect the dimensional quality of the casting.

Owens, R.

1997-10-01

307

Prototype casting fabrication by stereolithography.  

Science.gov (United States)

A new product development technology is emerging which could have a major impact on the investment casting industry. It's identified by several names, the most common of which is ''STEREOLITHOGRAPHY.'' This technology involves a three-dimensional printing...

W. E. Cromwell

1990-01-01

308

Project Vulcan Heater: Centerbody Casting.  

Science.gov (United States)

Specifications for casting the centerbody housing of the vulcan heater are provided. CD-4MCu steel has been specified for the centerbody and the properties of the steel are given. (ERA citation 04:051905)

1979-01-01

309

Manufacturing synthetic cast iron for NPP components  

Energy Technology Data Exchange (ETDEWEB)

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

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

1984-07-01

310

Erosion-corrosion  

International Nuclear Information System (INIS)

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

1999-01-01

311

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

2007-01-01

312

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

313

Vascular anatomy of the tibiofibular syndesmosis.  

UK PubMed Central (United Kingdom)

BACKGROUND: Injuries to the tibiofibular syndesmosis commonly cause prolonged ankle pain and disability. Syndesmotic injuries are associated with slower healing rates compared with rates for other ankle ligament injuries and typically result in longer time away from sports. To our knowledge, the vascular supply to the syndesmosis and its clinical implication have not previously been studied. The purpose of this study was to describe the vascular supply to the tibiofibular syndesmosis with use of a method of chemical debridement of cadaveric specimens. METHODS: Twenty-five matched pairs of adult cadaver legs, fifty legs total, were amputated below the knee. India ink, followed by Ward Blue Latex, was injected into the anterior tibial, peroneal, and posterior tibial arteries under constant manual pressure to elucidate the vascular supply of the ankle syndesmotic ligaments. Chemical debridement was performed with 6.0% sodium hypochlorite to remove soft tissue, leaving bones, ligaments, and casts of the vascular anatomy intact. The vascular supply to the syndesmosis was evaluated and recorded. RESULTS: The anterior vascularity of the syndesmosis was clearly visualized in forty-three of fifty specimens. The peroneal artery supplied an anterior branch (the perforating branch) that perforated the interosseous membrane, an average of 3 cm proximal to the ankle joint. This branch provided the primary vascular supply to the anterior ligaments in twenty-seven specimens (63%). The anterior tibial artery provided additional contribution to the anterior ligaments in the remaining sixteen specimens (37%). CONCLUSIONS: The location of the perforating branch of the peroneal artery places it at risk when injury to the syndesmosis extends to the interosseous membrane 3 cm proximal to the ankle joint. In the majority of specimens, injury to this vessel would result in loss of the primary blood supply to the anterior ligaments.

McKeon KE; Wright RW; Johnson JE; McCormick JJ; Klein SE

2012-05-01

314

Mechanism of corrosion  

International Nuclear Information System (INIS)

Corrosion processes on metallic materials are always electrochemical processes apart from a small number of exceptions. For area corrosion the metal removal is more or less completed over the entire area, whilst for local corrosion the situation is more clear. Crack corrosion phenomena may occur whenever a metallic material is subjected to a complex, i.e. chemical and mechanical stress. This article attempts to give an insight into this system problem and to provide an answer to the principles of the mechanism of corrosion. 19 figs., 2 tabs., 9 refs.

1989-01-01

315

Microacoustics of corrosion processes  

International Nuclear Information System (INIS)

Qualitative consideration is given to ultrasonic vibrations registered in a metal by a sensitive microacoustic apparatus in the processes of corrosion cracking, pitting, hydrogenation, dehydrogenation, applying galvanic coating. It is stated that microacoustics of corrosion processes should form an essential part of the theory of corrosion. Its immediate problems are the remote diagnostics of the early and subsequent stages of corrosion attack and also understanding of the role of the mutual resonance excitation of failure microzones and rearrangement of the crystalline structure in the development of rapid corrosion-mechanical failure

1977-01-01

316

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

317

3-dimensional resin casting and imaging of mouse portal vein or intrahepatic bile duct system.  

UK PubMed Central (United Kingdom)

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 structure(1,2), alterations in brain vasculature of a Alzheimer's disease mouse model(3), portal vein abnormalities in portal hypertensive and cirrhotic mice(4), developmental steps in rat lymphatic maturation between immature and adult lungs(5), immediate microvascular changes in the rat liver, pancreas, and kidney in response in to chemical injury(6). 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.

Walter TJ; Sparks EE; Huppert SS

2012-01-01

318

Towards Corrosion Detection System  

Directory of Open Access Journals (Sweden)

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

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

2010-01-01

319

Dictionary: corrosion and corrosion control. 2. rev. ed.  

International Nuclear Information System (INIS)

[en] This dictionary contains about 13.500 entries in each part of the following fields: Basic principles of corrosion (metals and their properties - electromotive series - passivity - lattice defects - corrodents - concepts of corrosion); Types of corrosion (corrosion of metals and non-metals - electrochemical corrosion - chemical corrosion - liquid-metal corrosion); Corrosion control (protection by influencing the state of a corroding system); Protection by coatings; Corrosion testing (field, plant, and laboratory testing - long-term and short-term tests). (orig./HP)

1991-01-01

320

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

2009-01-01

 
 
 
 
321

A new crevice corrosion testing method and its use in the investigation of oil stain  

Energy Technology Data Exchange (ETDEWEB)

A new electrochemical method was developed to investigate crevice corrosion and its inhibitors. A wire beam electrode was used to allow electrochemical parameters to be measured directly from the crevice area. As an example, oil stain was investigated using this method. Oil stain can result from a particular type of crevice corrosion that often occurs in the crevice between cast-iron, machine tool guideways. Oil stain harms the appearance, accuracy, and lifetime of the machine tool. Oil stain also occurs on the surface of piled steel machine parts if the antirust oil used is not of sufficient quality to control crevice corrosion.

Tan, Y.J. (Guangzhou Machine Tool Research Inst. (China))

1994-04-01

322

The three-dimensional feto-maternal vascular interrelationship during early bovine placental development: a scanning electron microscopical study  

Science.gov (United States)

Both the fetal and maternal microvasculature of bovine placentomes was examined by scanning electron microscopy of vascular casts. So far the development of the vascular architecture of the bovine placentome in early gestation has only been studied 2-dimensionally due to technical difficulties arising from the fragility of the early placental blood vessels. Repeated experiments led to the selection of the microvascular corrosion casts presented here. The vasculature of the maternal compartment is supplied by large caruncular stalk or spiral arteries, which release short maternal stem arteries. In the 3rd month of gestation, these arteries branch into several arterioles at their base, thus providing the vascular framework for the lower part of the septal walls of the primary crypts. In the 4th month, due to progressive longitudinal growth of the stem arteries, branching into arterioles occurs not only at the base, but over the whole length of the stem arteries. These arterioles supply the capillary complexes of the septa which resemble the major part of the septal vasculature and face the secondary crypts. Further indentation results in the formation of tertiary crypt capillary complexes, encircling the earlier secondary unit. From the 6th month of gestation the architecture resembles the fully developed maternal placenta with stem arteries running directly to the fetal side to branch into 4 to 6 arterioles, which turn back to enter secondary and tertiary septa. Maternal venules, collecting the blood from the capillary bed of secondary and tertiary septa, converge onto stem veins leaving the caruncle via branches of the uterine vein. The fetal part of the placentome is supplied by the cotyledonary arteries, which branch into fetal stem arteries that are the tributary to single villous trees. Over their whole course towards the maternal side, these give off arterioles entering secondary villi. The tertiary or terminal villous vasculature consists of capillaries, which are organised in serial capillary loops. This system is progressively elaborated in the course of gestation. In the 4th month there are only finger-like loops, whereas from the 6th month large fan-like structures can be observed. In early gestation the maternal and fetal blood vessels meet predominantly in a countercurrent fashion, changing to the less efficient crosscurrent exchange when the tertiary unit develops. These results indicate the development of a highly elaborated fetomaternal villous-crypt exchange system, already established in the 1st half of gestation, thus meeting the increasing needs of the fetus.

PFARRER, CHRISTIANE; EBERT, BRIGITTE; MIGLINO, MARIA ANGELICA; KLISCH, KARL; LEISER, RUDOLF

2001-01-01

323

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

324

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

International Nuclear Information System (INIS)

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

2002-01-01

325

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

326

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

1999-01-01

327

Grain boundary corrosion of copper canister weld material  

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-01-15

328

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

2006-01-01

329

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

International Nuclear Information System (INIS)

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

1993-01-01

330

Vascular Access for Hemodialysis  

Science.gov (United States)

... Kidney Failure Series : Vascular Access for Hemodialysis Vascular Access for Hemodialysis On this page: What is an ... Top ] What is a venous catheter for temporary access? If your kidney disease has progressed quickly, you ...

331

Society for Vascular Medicine  

Science.gov (United States)

... Procedures Physicians and Patients Should Question in Vascular Medicine Learn more about SVM & Choosing Wisely , an initiative ... for the vital position of editor of Vascular Medicine , the official of SVM. Learm more. SVM Joins ...

332

Vascular endothelial growth factor.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Vascular endothelial growth factor (VEGF) plays a crucial role in angiogenesis in development, in cancer and in other important diseases. VEGF regulates multiple endothelial cell functions including mitogenesis, permeability, vascular tone, and the production of vasoactive molecules. VEGF is related...

Zachary, I

333

[The collector system of the kidney. Applied anatomy based on the analysis of 3-dimensional casts].  

Science.gov (United States)

The kidney collector system were studied in 120 three-dimensional casts obtained by the injection-corrosion method. To the procurement of the first hundred casts, we made use of a polyester resin; however on the preparation of the last twenty we made use of a mixture containing latex and radiographic contrast as we intended to obtain, besides the casts, the roentgenograms. Two anatomic details, which have a great importance for endourology, were observed: a. the calices' cross draining the meso-renal region and the consequent inter-pelvis-calice (space (IPC) formation which is seen in the roentgenograms, b. a smaller calice which penetrates perpendicularly the surface of the renal pelvis or into the surface of a great calice. The urologists must appreciate these two anatomic structures, before the surgical procedures on the collector system. PMID:3680967

Sampaio, F J; Mandarim-De-Lacerda, C A; De Aragão, A H

1987-01-01

334

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; A. Kochma?ska

2009-01-01

335

Flow impact on cast ingots  

Science.gov (United States)

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

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

2005-10-01

336

The effect of repeated porcelain firings on corrosion resistance of different dental alloys  

Science.gov (United States)

PURPOSE The aim of this study was to evaluate the effects of repeated porcelain firing process on the corrosion rates of the dental alloys. MATERIALS AND METHODS Cr-Co, Cr-Ni and Pd-Ag alloys were used for this study. Each metal supported porcelain consisted of 30 specimens of 10 for 7, 9 and 11 firing each. Disc-shaped specimens 10 mm diameter and 3 mm thickness were formed by melting alloys with a propane-oxygen flame and casted with a centrifuge casting machine and then with the porcelain veneer fired onto the metal alloys. Corrosion tests were performed in quintuplicate for each alloy (after repeated porcelain firing) in Fusayama artificial saliva solution (pH = 5) in a low thermal-expansion borosilicate glass cell. Tamhane and Sheffe test was used to compare corrosion differences in the results after repeated firings and among 7, 9 and 11 firing for each alloy. The probability level for statistical significance was set at ?=0.05. RESULTS The corrosion resistance was higher (30 mV), in case of 7 times firing (Commercial). On the other hand, it was lower in case of 11 times firing (5 mV) (P<.05). CONCLUSION Repeated firings decreased corrosion resistance of Pd-Ag, Cr-Co and Cr-Ni alloys. The Pd-Ag alloy exhibited little corrosion in in vitro tests. The Cr-Ni alloy exhibited higher corrosion resistance than Cr-Co alloys in in vitro tests.

Karahan, Ismail; Polat, Serdar; Malkoc, Meral Arslan; Dalkiz, Mehmet

2013-01-01

337

The effect of repeated porcelain firings on corrosion resistance of different dental alloys.  

UK PubMed Central (United Kingdom)

PURPOSE: The aim of this study was to evaluate the effects of repeated porcelain firing process on the corrosion rates of the dental alloys. MATERIALS AND METHODS: Cr-Co, Cr-Ni and Pd-Ag alloys were used for this study. Each metal supported porcelain consisted of 30 specimens of 10 for 7, 9 and 11 firing each. Disc-shaped specimens 10 mm diameter and 3 mm thickness were formed by melting alloys with a propane-oxygen flame and casted with a centrifuge casting machine and then with the porcelain veneer fired onto the metal alloys. Corrosion tests were performed in quintuplicate for each alloy (after repeated porcelain firing) in Fusayama artificial saliva solution (pH = 5) in a low thermal-expansion borosilicate glass cell. Tamhane and Sheffe test was used to compare corrosion differences in the results after repeated firings and among 7, 9 and 11 firing for each alloy. The probability level for statistical significance was set at ?=0.05. RESULTS: The corrosion resistance was higher (30 mV), in case of 7 times firing (Commercial). On the other hand, it was lower in case of 11 times firing (5 mV) (P<.05). CONCLUSION: Repeated firings decreased corrosion resistance of Pd-Ag, Cr-Co and Cr-Ni alloys. The Pd-Ag alloy exhibited little corrosion in in vitro tests. The Cr-Ni alloy exhibited higher corrosion resistance than Cr-Co alloys in in vitro tests.

Tuncdemir AR; Karahan I; Polat S; Malkoc MA; Dalkiz M

2013-02-01

338

Early vascular aging (EVA): consequences and prevention  

Directory of Open Access Journals (Sweden)

Full Text Available Peter M NilssonDepartment of Clinical Sciences Medicine, Lund University, University Hospital, Malmö, SwedenAbstract: It has often been recognized that a discrepancy exists during the clinical consultation between the chronological age of a patient on the one hand with the signs and symptoms of biological age that can be recorded on the other hand. In cardiovascular medicine this is obvious when a heavy smoker presents with features of early biological aging, for example skin appearance and impaired lung function. This could also be extrapolated to vascular function as the target for numerous cardiovascular risk factors, thereby increasing the risk of early cardiovascular disease (CVD). Both new and old treatment modalities can play a role for the prevention of early vascular aging, first of all smoking cessation and improved lifestyle in general, but later on also the use of drugs such as statins or agents that block the renin – angiotensin system (RAS). New classes of drugs are currently being tested for CVD prevention, including glitazones and rimonabant, even if adverse effects (heart failure and depression) might restrict their usefulness. Results from ongoing intervention studies will eventually cast new light on possibilities to prevent the development of vascular aging.Keywords: aging, cardiovascular, diabetes, hypertension, risk factor, smoking, vascular

Peter M Nilsson

2008-01-01

339

Oil ash corrosion  

International Nuclear Information System (INIS)

[en] 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

1991-01-01

340

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

 
 
 
 
341

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

342

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

343

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

UK PubMed Central (United Kingdom)

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.

Santos TC; Oliveira MF; Dantzer V; Miglino MA

2012-07-01

344

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

345

The corrosion of polymers; Corrosion des polymeres  

Energy Technology Data Exchange (ETDEWEB)

After having introduced the aging notion or polymers corrosion, the different general mechanisms of these materials degradation are outlined: physical, mechanical, thermochemical, photochemical or hydrolytic mechanisms. The influence of the moisture effect is then given. (O.M.)

Tremillon, J.M. [ALPHACAN, 78 - La Celle-Saint-Cloud (France)

1998-10-01

346

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

UK PubMed Central (United Kingdom)

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.

Nguyen TL; Blanquet A; Staiger MP; Dias GJ; Woodfield TB

2012-07-01

347

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

International Nuclear Information System (INIS)

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

2011-01-01

348

Features based representation for casting  

Energy Technology Data Exchange (ETDEWEB)

This paper reports a method for automatic recognition of casting features from a Boundary Representation of the solid model. The proposed method is based principally on the evaluation of two topological invariant of concave parts of the modeled object. Some aspects of the {open_quotes}domain of application{close_quotes} of the method are considered and seven categories of casting features identified. In this work the attention is placed on the influence of the geometry of the molded object, in drawing problems and in core identification.

Di Stefano, P. [Universita degli Studi di L`Aquila (Italy)

1996-12-31

349

Modified approach to construct a vascularized coral bone in rabbit using an arteriovenous loop.  

Science.gov (United States)

The most important factor for the survival of thick three-dimensional tissues is the degree of vascularization. In this study, a modified arteriovenous loop (AVL) model was developed to prefabricate an axial vascularized tissue-engineered coral bone. In group A (n = 28), an arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. The AVL was placed in a coral block (6 x 8 x 10 mm (3)) as a vascular carrier. The complex was wrapped with polytetrafluoroethylene membrane and implanted subcutaneously. In group B (n = 20), there was no vascular carrier, and the same dimensional coral was directly implanted beneath inguinal skin. After 2, 4, 6, and 8 weeks, the rabbits were perfused with heparinized saline (for scanning electron microscopy), India ink (for histological examination), and ethylene perchloride (for vascular casts) via the abdominal aorta. In group A, histology showed that newly formed vasculature extended over the surfaces and invaded the entire coral blocks. The vascular density was significantly superior to that in group B. Vascular casts showed that new blood vessels robustly sprouted from the AVL. Scanning electron microscopy demonstrated that there were minute sprouting cavities in the vascular endangium. In this model, an axial vascularized coral bone could be effectively constructed. PMID:20013595

Dong, Qing-shan; Lin, Cheng; Shang, Hong-tao; Wu, Wei; Chen, Fu-lin; Ji, Xi-tuan; Liu, Yan-pu; Zhang, Jun-rui; Mao, Tian-qiu

2009-12-10

350

Modified approach to construct a vascularized coral bone in rabbit using an arteriovenous loop.  

UK PubMed Central (United Kingdom)

The most important factor for the survival of thick three-dimensional tissues is the degree of vascularization. In this study, a modified arteriovenous loop (AVL) model was developed to prefabricate an axial vascularized tissue-engineered coral bone. In group A (n = 28), an arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. The AVL was placed in a coral block (6 x 8 x 10 mm (3)) as a vascular carrier. The complex was wrapped with polytetrafluoroethylene membrane and implanted subcutaneously. In group B (n = 20), there was no vascular carrier, and the same dimensional coral was directly implanted beneath inguinal skin. After 2, 4, 6, and 8 weeks, the rabbits were perfused with heparinized saline (for scanning electron microscopy), India ink (for histological examination), and ethylene perchloride (for vascular casts) via the abdominal aorta. In group A, histology showed that newly formed vasculature extended over the surfaces and invaded the entire coral blocks. The vascular density was significantly superior to that in group B. Vascular casts showed that new blood vessels robustly sprouted from the AVL. Scanning electron microscopy demonstrated that there were minute sprouting cavities in the vascular endangium. In this model, an axial vascularized coral bone could be effectively constructed.

Dong QS; Lin C; Shang HT; Wu W; Chen FL; Ji XT; Liu YP; Zhang JR; Mao TQ

2010-02-01

351

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; A. Brodziak-Hyska; C. Kolan

2012-01-01

352

Casting behavior of titanium alloys in a centrifugal casting machine.  

UK PubMed Central (United Kingdom)

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

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

2003-05-01

353

Casting behavior of titanium alloys in a centrifugal casting machine.  

Science.gov (United States)

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

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

2003-05-01

354

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-10-15

355

Novel corrosion inhibitor technology  

Energy Technology Data Exchange (ETDEWEB)

A novel, patented corrosion inhibitor technology has been identified for use in heat transfer applications such as automotive and heavy-duty coolant. The new technology is based on a low-toxic, virtually depletion-free carboxylic acid corrosion inhibitor package that performs equally well in mono ethylene glycol and in less toxic propylene glycol coolants. An aqueous inhibitor concentrate is available to provide corrosion protection where freezing protection is not an issue. In the present paper, this inhibitor package is evaluated in the different base fluids: mono ethylene glycol, mono propylene glycol and water. Results are obtained in both standardized and specific corrosion tests as well as in selected field trials. These results indicate that the inhibitor package remains effective and retains the benefits previously identified in automotive engine coolant applications: excellent corrosion protection under localized conditions, general corrosion conditions as well as at high temperature.

Van de Ven, P.; Fritz, P.; Pellet, R. [Texaco Global Products, Beacon, NY (United States)

1999-11-01

356

Platform probes monitor corrosion  

Energy Technology Data Exchange (ETDEWEB)

Corrosion control presents offshore producers with a difficult decision. An inadequate program will result in equipment failures. Yet, a brute force approach to corrosion can run into millions of dollars in a single field. Based on a report by the Phillips Petroleum Co., the problem can be solved through the use of corrosion detection and monitoring equipment. It can alert the operator as to which wells are under attack and which are not. A corrosion program can then be planned based on current corrosion data. Thus, not only can workovers be scheduled prior to failure or advance corrosion damage, chemical costs can be drastically reduced. Monitoring equipment ranges from portable units to very elaborate systems.

Cooper, G.

1983-10-05

357

Pipe Lines – External Corrosion  

Directory of Open Access Journals (Sweden)

Full Text Available Two areas of corrosion occur in pipe lines: corrosion from the medium carried inside the pipes; corrosion attack upon the outside of the pipes (underground corrosion. Electrolytic processes are also involved in underground corrosion. Here the moisture content of the soil acts as an electrolyte, and the ions required to conduct the current are supplied by water-soluble salts (chlorides, sulfates, etc.) present in the soil. The nature and amount of these soluble materials can vary within a wide range, which is seen from the varying electrical conductivity and pH (varies between 3 and 10). Therefore the characteristics of a soil will be an important factor in under-ground corrosion.

Dan Babor

2008-01-01

358

Corrosion testing in coal preparation environments  

Energy Technology Data Exchange (ETDEWEB)

Equipment that is used in coal preparation is subjected to various forms of corrosion and mechanical wear. The Kentucky Center for Energy Research Laboratory is conducting ongoing wear tests at TVA's Paradise coal preparation plant to measure the performance of typical metals of construction in various process areas of the plant. Results of a 2500 hour test are reported and compared to baseline results that were obtained from an earlier test. Comparison of data from these two tests indicate that wear results are reasonably reproducible within the operating variations of the plant. Stainless steel and high chromium cast iron samples experience low or negligible wastage rates. Low carbon steel, Cor-Ten A, Ni Hard 1 and Ni Hard 4 samples experienced significant wastage rates as a result of general corrosion attack due to the presence of dissolved oxygen in highly conductive process water. Localized corrosion was also observed in all samples except for the austenitic stainless steels. The highest wastage rates for almost all samples occurred in the location handling the largest-sized fraction of coal in the plant, indicating an added abrasive wear contribution. Long term testing in the plant continues.

Heink, J.B.; Stencel, J.M.; Abner, T.; Gonzalez, R.E.

1987-01-01

359

Thermal transport properties of grey cast irons.  

Science.gov (United States)

Thermal diffusivity and thermal conductivity of grey cast iron have been measured as a function of graphite flake morphology, chemical composition, and position in a finished brake rotor. Cast iron samples used for this investigation were cut from ''step ...

R. L. Hecht R. B. Dinwiddie W. D. Porter H. Wang

1996-01-01

360

Investment Castings: A National Security Assessment.  

Science.gov (United States)

A national security/industrial capabilities assessment of the domestic investment casting industry. The report includes a detailed review of the investment casting industry and its performance, production capabilities, surge and mobilization capabilities,...

1987-01-01

 
 
 
 
361

Mundrabilla: A Microgravity Casting  

Science.gov (United States)

The name "Mundrabilla" is applied to two nickel-iron meteorite masses (combined mass over 22,700 kg), which apparently were a single mass before atmospheric entry [1]. A medium octahedrite, Mundrabilla exhibits the microstructural features common to other nickel-iron meteorites such as Widmanstatten structure and troilite; however, its macrostructure is anything but common. Described by Buchwald as "anomalous" [1], Mundrabilla's macrostructural morphology is characterized by strikingly prominent, rounded Widmanstatten areas separated by regions of sulfur segregation (Fig. 1). While microstructural development of a metal can reflect both solidification and solid state reactions, macrostructural features are determined during solidification. Thus, a typical metallurgist, unfamiliar with microgravity solidification, might describe Mundrabilla's macrostructure as an "anomalous" casting. Those familiar with microgravity solidification might characterize Mundrabilla's macrostructural features as due to solidification of two immiscible liquids [2]--one rich in nickel-iron, the other rich in sulfur. Combining these observations, Mundrabilla's macrostructural features are consistent with that of a liquid mass solidified under microgravity conditions [3,4]. Since nickel-iron meteorite cooling rates often serve as the foundation for assumptions about the formation of solar system bodies, information on the solidification time for the Mundrabilla mass may give additional insights. How long did it take for Mundrabilla, with a minimum "as received" mass of approximately 22,700 kg to solidify? Because Mundrabilla's mass before atmospheric entry is unknown, we take as an upper boundary a mass of 4.1 x 10^15kg. These masses, assumed spherical, range in diameter between 1.8 meters and 10 kilometers, respectively. Mundrabilla can be idealized as a pure iron liquid mass cooling from the melting point of pure iron (1535C) by radiation into space at absolute zero. The latent heat of transformation for iron is used to calculate "excess temperature," i.e., the amount the mass temperature can be raised due to recalescence. Solidification is considered complete when the center of the mass is solid. Fig. 2, is a plot of the solidification times for an iron mass in the range 1.8 meters to 10 kilometers in diameter. At the lower bound, solidification time is about 1.6 hours; at the upper bound, solidification time is on the order of 3,400 years. References: [1] Buchwald V. F. (1975) Handbook of Iron Meteorites, University of California, Berkeley. [2] Carlberg T. and Fredriksson H. (1980) Metallurgical Transactions A, 11A, 1665-1676. [3] Budka P. Z. (1988) Metallurgical Transactions A, 19A, 1919-1923. [4] Budka P. Z. (1988) J. Metals, 40, 9, 6-9. Fig. 1, which appears here in the hard copy, shows Mundrabilla--a scale in inches. Figure 2, which appears here in the hard copy, shows solidification time vs. diameter.

Budka, P. Z.; Viertl, J. R. M.

1993-07-01

362

Erosion-corrosion; Erosionkorrosion  

Energy Technology Data Exchange (ETDEWEB)

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

Aghili, B

1999-05-01

363

Electrochemical gases of corrosion  

Energy Technology Data Exchange (ETDEWEB)

The author explains in easily understandable language the electrochemical series of metals and its determination, the practical electromotive chain in waters, Nernst's equation, oxygen and hydrogen electrode and their ph-dependence, and the current-voltage curves of metals. Simple models with regard to the electrochemical corrosion mechanism are discussed. Finally possibilities for active and passive corrosion protection (cathode and anode protection against corrosion in the former, coatings in the latter case) are discussed.

Hupfeld, J.

1985-11-01

364

Marine corrosion. Final report  

Energy Technology Data Exchange (ETDEWEB)

This report is a review of marine corrosion of metals and alloys which is to be included in the new Handbook of Ocean Engineering, to be published by Academic Press in 1985. The report describes marine environments, the types of marine corrosion encountered, cathodic protection and alloys used in marine applications. Emphasis is placed on describing the types of corrosion generally found and the preventative measures employed.

Sedriks, A.J.

1985-04-24

365

N, s containing corrosion inhibitors  

Energy Technology Data Exchange (ETDEWEB)

This patent describes a method of inhibiting corrosion of metals, which comprises treating a system where metals are susceptible to corrosion with a corrosion inhibiting amount of a thio substituted quaternary ammonium salt.

Haslegrave, J.A.; Sullivan, D.S.

1987-06-16

366

A study of the connection mechanism of cast-in high chromium cast iron - carbon cast steel by cast-in process  

Energy Technology Data Exchange (ETDEWEB)

The connection mechanism of high chromium cast iron--carbon cast steel by cast-in process was studied by analyzing the microstructure and the alloying component in the transition zone with scanning electron microscope observation. The experiment results show that sordite pearlite and ferrite constitute microstructure of transition zone and the connection of metallurgy is formed because of the diffusion reaction, interface reaction and formation of the new compound phase during the cast-in process. (orig.)

Liu Xiang; Shen Shuxi; Xu Qiaoyu [School of Mechanical Engineering, Xinjiang Univ., Urumqi, XJ (China)

2003-07-01

367

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

368

Corrosion control. 2. ed.  

International Nuclear Information System (INIS)

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

2001-01-01

369

Corrosion of support materials  

International Nuclear Information System (INIS)

Results from a heavily fouled 19 tube C-E model boiler test to investigate the potential for egg crate corrosion in aggressively fouled AVT chemistry are reported. Substantial support plate and egg crate corrosion was produced in this test. Carbon steel drilled support plates exhibited extensive denting which resulted in flow hole ligament cracking. Corrosion of the carbon steel egg crate, through-wall at areas of tube contact, resulted in denting of the Alloy 600 heat transfer tubes. Corrosion performance of the 409 stainless steel egg crate was improved compared to the carbon steel egg crate although localized through-wall corrosion was noted. The results from the above test and previously reported tests were compared based on the following simplifying assumptions: maximum dent size and/or corrosion penetrations utilized, average bulk water chloride concentrations, pilling bedworth ratios, pot and model boilers data are equivalent, heat flux not significantly variable, and plot is semi-quantitative. Conclusions based on plots of maximum corrosion rates as a function of average bulk water chloride concentrations are presented. Finally, the corrosion performance of the various materials of construction for support systems were ranked for each test. Final material selection for future support systems must be based on a balance of thermal/hydraulic, metallurgical, corrosion and design considerations.

1985-01-01

370

Corrosion in bioprocessing applications.  

UK PubMed Central (United Kingdom)

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.

Junker B

2009-01-01

371

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

2008-05-30

372

Compilation of Hanford corrosion studies  

International Nuclear Information System (INIS)

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

1975-01-01

373

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

374

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

375

Tensile properties of weld joints of aluminum alloy casting and rolled plates; Aluminium gokin imono-atsuenzai yosetsu tsugite no incho tokusei  

Energy Technology Data Exchange (ETDEWEB)

A welding process may be simplified largely if it is performed by utilizing casting in sections with complex shapes requiring formation and rolled plates in simple-shaped sections. Evaluations were given on mechanical properties of weld joints made with highly anti-corrosive Al alloy rolled plates of marine use, and joints made with casting having the properties corresponding to those of the rolled plates. Welding the casting with the rolled material was found possible, and about the same joint strength as the casting being a base material was obtained. Both of MIG and TIG welding techniques result in weld metals presenting greater tensile strength than the base material of the casting (cast by using a metal mold and a sand mold). Casting made with the metal mold also showed good bending performance. The MIG welding is prone to generate pores in welds caused by hydrogen, but since a fracture may occur in the base material of the casting in weld joints made with castings, it does not affect static tensile strength. The TIG welding generates fewer pores resulting in good welded condition, but because of the greater thermal effect on the base material, the joint strength was found inferior to that in welds of the MIG welding. The MIG welding may better be used from the strength and reliability viewpoints. It is important to reduce hydrogen absorption, suppress pore generation, and reduce thermal impact. 7 refs., 10 figs., 5 tabs.

Kawashima, S.; Murakami, M.; Handa, M.; Kudo, Y.; Miura, Y.; Hasegawa, Y.; Kono, T.; Handa, K.; Kumai, S.; Kamei, H.

1997-09-25

376

Corrosion resistance of neodymium composite materials reinforced with metal powders  

Directory of Open Access Journals (Sweden)

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

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

2012-01-01

377

Inoculation Effects of Cast Iron  

Directory of Open Access Journals (Sweden)

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

E. Fra?; M. Górny

2012-01-01

378

Tape Casting of Magnesium Oxide.  

Science.gov (United States)

A tape casting procedure for fabricating ceramic magnesium oxide tapes has been developed as a method to produce flat sheets of sintered MgO that are thin and porous. Thickness of single layer tapes is in the range of 200-400 (micro)m with corresponding s...

A. Ayala D. Bencoe E. L. Corral M. Reitere R. Shah R. E. Loehman

2008-01-01

379

Tape casting of magnesium oxide.  

Energy Technology Data Exchange (ETDEWEB)

A tape casting procedure for fabricating ceramic magnesium oxide tapes has been developed as a method to produce flat sheets of sintered MgO that are thin and porous. Thickness of single layer tapes is in the range of 200-400 {micro}m with corresponding surface roughness values in the range of 10-20 {micro}m as measured by laser profilometry. Development of the tape casting technique required optimization of pretreatment for the starting magnesium oxide (MgO) powder as well as a detailed study of the casting slurry preparation and subsequent heat treatments for sintering and final tape flattening. Milling time of the ceramic powder, plasticizer, and binder mixture was identified as a primary factor affecting surface morphology of the tapes. In general, longer milling times resulted in green tapes with a noticeably smoother surface. This work demonstrates that meticulous control of the entire tape casting operation is necessary to obtain high-quality MgO tapes.

Ayala, Alicia; Corral, Erica L.; Loehman, Ronald E.; Bencoe, Denise Nora; Reiterer, Markus; Shah, Raja A.

2008-02-01

380

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

 
 
 
 
381

Complex vascular anomalies.  

UK PubMed Central (United Kingdom)

The classification system for vascular anomalies now used by experts worldwide comprises two distinct disease entities that differ in their biologic and pathologic features: vascular tumors and vascular malformations. Vascular tumors include infantile and congenital hemangiomas, tufted angiomas, and kaposiform hemangioendotheliomas. Infantile hemangiomas, the most common vascular anomaly, generally have a predetermined life cycle (proliferation and subsequent involution). GLUT-1, a glucose transporter, is a marker for these specific lesions during all phases of development. Vascular malformations are classified according to their vascular tissue of origin and include capillary, venous, arteriovenous, lymphatic, and mixed malformations. Complex lymphatic malformations and complex mixed malformations, which may have most vascular components, are the most difficult vascular malformations to successfully treat. These lesions are present at birth and often expand or grow in response to trauma, infection, or hormonal changes. Imaging advancements have enabled more accurate assessments and improved management of vascular anomalies. In addition, many lesions are now being managed with targeted pharmacologic therapy. Propranolol and steroids are used for complex or disfiguring tumors, and new anti-angiogenesis inhibitors such as sirolimus are selectively used to treat lymphatic and venous lymphatic malformations that are poorly responsive to sclerotherapy, embolization, and surgical excision. Multimodal therapies are often essential for complex lesions and require the combined expertise of an interdisciplinary team.

Azizkhan RG

2013-10-01

382

Studies of the transition zone in steel – chromium cast iron bimetallic casting  

Directory of Open Access Journals (Sweden)

Full Text Available In this work authors presented the results of transition zone studies on steel – cast iron interface in bimetallic casting. During the investigations cylindrical castings with different diameter were prepared of cast iron with steel rods placed in the center. From each bimetallic casting a microsection was prepared for microhardness tests and metalographic analysis, consisting of transition zone measurement, point and linear analysis as well as quantitative analysis.

S. Tenerowicz; J. Sucho?; M. Cholewa

2010-01-01