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Sample records for cd cr ni

  1. Effect of Grain Position within a Panicle and Variety on As, Cd, Cr, Ni, Pb Concentrations in japonica Rice

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Two japonica rice varieties, a compact panicle (CP) Xiushui 63 and a loose panicle (LP) Xiushui 11 were grown in a slightly contaminated paddy field, to determine the effect of grain positions within a panicle and variety on grain As, Cd, Cr, Ni and Pb concentrations. There wasa significant difference in grain As, Cd, Cr, Ni and Pb concentrations among grain positions, and the extent of the difference was variety- and metal-specific; Xiushui 63 showed greater difference than Xiushui 11, and As, Cd, Cr and Pb being greater than Ni. The top grains (TG) of a panicle had higher As, Cd and Ni concentrations than the middle ones (MG), and the bottom ones (BG) contained the lowest. With regard to Cr and Pb, the case was opposite. Significantly positive correlations were found between grain weight and As, Cd, Ni concentrations, but there was a negative correlation between grain weight and Cr, and Pb concentrations. There was a remarkable variation in grain filling pattern among grains within a panicle, and between Xiushui 63 and Xiushui 11. In comparison with MG and TG, BG had the lowest grain filling rate and grain weight, leading to obvious difference in grain weight among grains within a panicle, and a greater difference for Xiushui 63 than for Xiushui 11. The regression analysis showed that grain As and Cd concentrations were positively correlated with the maximum grain filling rate (GRm),while negatively correlated with the required time for reaching the maximum grain filling rate (Tpoi). Concerning Cr and Pb, the case was just reverse. It is suggested that As and Cd accumulation in grains might be accompanied by the carbohydrate accumulations, while Cr and Pb accumulation displayed a different pattern.

  2. Cd, Ni, Cr and Pb distribution in biosolid pellets used as soil amendment

    Science.gov (United States)

    Jordán, Manuel M.; Rincón-Mora, Beatriz; Belén Almendro-Candel, María; Navarro Pedreño, Jose; Gómez Lucas, Ignacio; Bech, Jaume; Roca, Nuria; Pardo, Francisco

    2016-04-01

    The application of biosolids to a soil is a method that offers important benefits (Navarro et al. 2003). The transport and application costs are quite low (mostly if they are dehydrated biosolids or pellets) if soils are located near a wastewater treatment plant. It is possible to recycle nutrients (N, P, and K) and organic matter by improving the physical and chemical characteristics of the soil and by reducing the fertilizer costs. However, the use of biosolids may also has several problems, such as the presence of quantities of metals that could be toxic for plants or could contaminate ground-waters after being leached. Heavy metals are one of the most serious environmental pollutants because of its high toxicity, abundance and easy accumulation by plant (Soriano-Disla et al. 2014; Rosen and Chen 2014). Contamination of soils by potentially toxic elements (e.g. Cd, Ni, Cr, Pb) from amendments of biosolids is subject to rigorous controls within the European Union. The present study was designed to examine the partition of selected heavy metals in biosolid pellets, and also to relate the distribution patterns of these metals. Samples were collected from the treatment of urban wastewater at the drying grounds of a wastewater processing plant. The samples correspond to biosolids with humidities below 20% and are representative of the three horizons within the pile: the isolation surface (H1), the mesophilous area (H2), and the thermophilous area (H3). Biosolid aggregates were placed in a pellet press and then compacted. Total content of metals was determined following microwave digestion and analysed by ICP/MS. Triplicate samples were weighed in polycarbonate centrifuge tubes and sequentially extracted. The distribution of chemical forms of Cd, Ni, Cr, and Pb in the biosolids was studied using a sequential extraction procedure that fractionates the metal into soluble-exchangeable, specifically sorbed-carbonate bound, oxidizable, reducible, and residual forms. The

  3. Heavy metal content (Cd, Ni, Cr and Pb) in soil amendment with a low polluted biosolid

    Science.gov (United States)

    Gomez Lucas, Ignacio; Lag Brotons, Alfonso; Navarro-Pedreño, Jose; Belén Almendro-Candel, Maria; Jordán, Manuel M.; Bech, Jaume; Roca, Nuria

    2016-04-01

    The progressively higher water quality standards in Europe has led to the generation of large quantities of sewage sludge derived from wastewater treatment (Fytili and Zabaniotou 2008). Composting is an effective method to minimize these risks, as pathogens are biodegraded and heavy metals are stabilized as a result of organic matter transformations (Barker and Bryson 2002; Noble and Roberts 2004). Most of the studies about sewage sludge pollution are centred in medium and high polluted wastes. However, the aim of this study was to assess the effects on soil heavy metal content of a low polluted sewage sludge compost in order to identify an optimal application rate based in heavy metal concentration under a period of cultivation of a Mediterranean horticultural plant (Cynara carducnculus). The experiment was done between January to June: rainfall was 71 mm, the volume of water supplied every week was 10.5 mm, mean air temperatures was 14.2, 20.4 (maximum), and 9.2◦C (minimum). The soil was a clay-loam anthrosol (WRB 2006). The experimental plot (60 m2) was divided into five subplots with five treatments corresponding to 0, 2, 4, 6, and 8 kg compost/m2. Three top-soil (first 20 cm) samples from each treatment were taken (January, April and June) and these parameters were analysed: pH, electrical conductivity, organic matter and total content of heavy metals (microwave acid digestion followed by AAS-spectrometry determination). The results show that sewage sludge compost treatments increase the organic matter content and salinity (electrical conductivity of the soils) and diminish the pH. Cd and Ni total content in top-soil was affected and both slightly reduce their concentration. Pb and Cr show minor changes. In general, the application of this low polluted compost may affect the mobility of Cd and Ni due to the pH modification and the water added by irrigation along time but Pb and Cr remain their content in the top-soil. References Barker, A.V., and G.M. Bryson

  4. Greenhouse evaluation of EDTA effectiveness at enhancing Cd, Cr, and Ni uptake in Helianthus annuus and Thlaspi caerulescens

    Energy Technology Data Exchange (ETDEWEB)

    Munn, J.; January, M.; Cutright, T.J. [Dept. Civil Engineering, The Univ. of Akron, OH (United States)

    2008-04-15

    Background, aims and scope. Phytoremediation is a promising means for the treatment of heavy metal contamination. Although several species have been identified as hyperaccumulators, most studies have been conducted with only one metal. Experiments were conducted to investigate the ability of Helianthus annuus and Thlaspi caerulescens to simultaneously uptake Cd, Cr and Ni. Materials and methods. The efficiency of plants grown in a sandy-loam soil was investigated. The ability of two EDTA concentrations (0.1 and 0.3 g kg{sup -1}) for enhancing the phytoremediation of Cd, Cr and Ni at two different metal concentrations (24.75 mg kg{sup -1} and 90 mg kg{sup -1}) was studied. Results. Thlaspi hyperaccumulated Ni with 0.1 g kg{sup -1} EDTA. When the EDTA dosage was increased to 0.3 g kg{sup -1}, Thlaspi was able to hyperaccumulate both Ni and Cr. Since Thlaspi is a low-biomass plant, it was considered insufficient for full-scale applications. Helianthus annuus hyperacummulated Cr (with 0.1 g kg{sup -1} EDTA) and Cd (0.3 g kg{sup -1} EDTA). Discussion. When the contamination was 8.25 mg kg{sup -1} per metal, the total metal uptake was 10-25% (1.35 to 2.12 mg) higher and had the same uptake selectivity (Cr>>Cd>Ni) for both EDTA levels. It was hypothesized that complexation with EDTA interfered with Ni translocation. For these experiments, the optimal results were obtained with the H. annuus-0.1 g kg{sup -1} EDTA combination. Conclusions. Although the use of EDTA did increase the amount of metal that could be extracted, care should be taken during in-situ field applications. Chelators can also increase the amount of metals that are leached past the root zone. Metal leaching and subsequent migration could lead to ground water contamination as well as lead to new soil contamination. Recommendations and perspectives. Additional research to identify the optimal EDTA dosage for field applications is warranted. This is necessary to ensure that the metals do not leach past the

  5. As, Cd, Cr, Ni and Pb pressurized liquid extraction with acetic acid from marine sediment and soil samples

    Energy Technology Data Exchange (ETDEWEB)

    Moreda-Pineiro, Jorge [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna. Campus da Zapateira s/n. E-15071. A Coruna (Spain)]. E-mail: jmoreda@udc.es; Alonso-Rodriguez, Elia [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna. Campus da Zapateira s/n. E-15071. A Coruna (Spain); Lopez-Mahia, Purificacion [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna. Campus da Zapateira s/n. E-15071. A Coruna (Spain); University Institute of Environment, University of A Coruna, Pazo de Longora, Lians, E-15179. Oleiros (Spain); Muniategui-Lorenzo, Soledad [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna. Campus da Zapateira s/n. E-15071. A Coruna (Spain); Prada-Rodriguez, Dario [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna. Campus da Zapateira s/n. E-15071. A Coruna (Spain); University Institute of Environment, University of A Coruna, Pazo de Longora, Lians, E-15179. Oleiros (Spain); Moreda-Pineiro, Antonio [Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Chemistry, University of Santiago de Compostela, Avenida das Ciencias, s/n. E-15782, Santiago de Compostela (Spain); Bermejo-Barrera, Adela [Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Chemistry, University of Santiago de Compostela, Avenida das Ciencias, s/n. E-15782, Santiago de Compostela (Spain); Bermejo-Barrera, Pilar [Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Chemistry, University of Santiago de Compostela, Avenida das Ciencias, s/n. E-15782, Santiago de Compostela (Spain)

    2006-12-15

    Rapid leaching procedures by Pressurized Liquid Extraction (PLE) have been developed for As, Cd, Cr, Ni and Pb leaching from environmental matrices (marine sediment and soil samples). The Pressurized Liquid Extraction is completed after 16 min. The released elements by acetic acid Pressurized Liquid Extraction have been evaluated by inductively coupled plasma-optical emission spectrometry. The optimum multi-element leaching conditions when using 5.0 ml stainless steel extraction cells, were: acetic acid concentration 8.0 M, extraction temperature 100 deg. C, pressure 1500 psi, static time 5 min, flush solvent 60%, two extraction steps and 0.50 g of diatomaceous earth as dispersing agent (diatomaceous earth mass/sample mass ratio of 2). Results have showed that high acetic acid concentrations and high extraction temperatures increase the metal leaching efficiency. Limits of detection (between 0.12 and 0.5 {mu}g g{sup -1}) and repeatability of the over-all procedure (around 6.0%) were assessed. Finally, accuracy was studied by analyzing PACS-2 (marine sediment), GBW-07409 (soil), IRANT-12-1-07 (cambisol soil) and IRANT-12-1-08 (luvisol soil) certified reference materials (CRMs). These certified reference materials offer certified concentrations ranges between 2.9 and 26.2 {mu}g g{sup -1} for As, from 0.068 to 2.85 {mu}g g{sup -1} for Cd, between 26.4 and 90.7 {mu}g g{sup -1} for Cr, from 9.3 to 40.0 {mu}g g{sup -1} for Ni and between 16.3 and 183.0 {mu}g g{sup -1} for Pb. Recoveries after analysis were between 95.7 and 105.1% for As, 96.2% for Cd, 95.2 and 100.6% for Cr, 95.7 and 103% for Ni and 94.2 and 105.5% for Pb.

  6. Removal of As, Cd, Cr, Cu, Ni and Zn from polluted water using an iron based sorbent

    DEFF Research Database (Denmark)

    Genc-Fuhrman, Hülya; Wu, P.; Zhou, Y.;

    2008-01-01

    In this study fixed-bed sorption filters are filled with an iron based sorbent (ferrosorp plus, FP) and used to remove a range of heavy metals (i.e. As, Cd, Cr, Cu, Ni, and Zn) from polluted water. It is found that FP is very effective at simultaneous removal of the heavy metals, and the magnitude...... inflow pH of 6.8 and heavy metal concentration of ≈2.8 μM. It is concluded that FP has high affinity to heavy metals and it can be used (e.g. as a filter medium) to treat waters containing a wide range of heavy metals, e.g. stormwater, industrial wastewater....

  7. Extratores para Cd, Cu, Cr, Mn, Ni, Pb e Zn em LATOSSOLOS tratados com biossólido e cultivados com milho Extractants for Cd, Cu, Cr, Mn, Ni, Pb and Zn in biossolid-amanded Oxisols cultivated with corn

    Directory of Open Access Journals (Sweden)

    Ana Rosa Martins dos Anjos

    2001-06-01

    Full Text Available O uso de biossólidos (lodo de esgoto em áreas agrícolas cria uma demanda por informações sobre o extrator mais adequado para se prever disponibilidade de metais pesados, presentes nesse resíduo, para as espécies vegetais cultivadas nessas áreas. A eficiência dos extratores HCl 0,1 mol L-1, Mehlich 3 e DTPA 0,005 mol L-1 pH 7,3 e da água régia na previsão da fitodisponibilidade de metais pesados presentes em solos tratados com biossólido foi avaliada através de um experimento com milho cultivado em LATOSSOLO VERMELHO Distrófico (LVd e LATOSSOLO AMARELO Distrófico (LAd. As parcelas experimentais foram vasos com capacidade para 0,5 m³de terra, distribuídos em blocos ao acaso, em esquema fatorial 4 x 4, quatro tratamentos (LVd+lodo, LVd, LAd+lodo e LAd e quatro métodos de extração com quatro repetições. O biossólido foi aplicado antes do cultivo do milho, numa quantidade total de 388 Mg ha-1, base seca, parcelada em 5 vezes espaçadas de 2 meses cada. Antes de semear o milho foi feita a amostragem da terra a 0-0,20 m, que foi analisada para teor total dos metais presentes com água régia e teores trocáveis removidos pelos extratores: solução 0,1 mol L-1 de HCl, Mehlich 3; DTPA-TEA pH 7,3. As plantas foram separadas em folha diagnose, folhas ao final do ciclo, pendão, colmo, bainha, sabugo, palha e grãos. Apesar da quantidade de biossólido aplicada aos solos, os teores totais dos metais analisados não excederam os limites críticos estabelecidos pela United States Environmental Protection Agency (USEPA e pela Diretriz da Comunidade Européia. As correlações feitas entre teor de metais presentes nas várias partes das plantas e teores dos metais removidos pelos diferentes extratores evidenciaram que Mehlich 3 foi eficiente apenas na previsão da fitodisponibilidade de Cu e Zn. Nenhum dos extratores testados foi eficiente na previsão da disponibilidade de Cd, Cr, Ni e Pb para as plantas de milho.The use of biossolids

  8. The effect of EDTA and citric acid on phytoremediation of Cd, Cr, and Ni from soil using Helianthus annuus

    Energy Technology Data Exchange (ETDEWEB)

    Turgut, Cafer; Katie Pepe, M.; Cutright, Teresa J

    2004-09-01

    The possibility to clean heavy metal contaminated soils with hyperaccumulator plants has shown great potential. One of the most recently studied species used in phytoremediation applications are sunflowers. In this study, two cultivars of Helianthus annuus were used in conjunction with ethylene diamine tetracetic acid (EDTA) and citric acid (CA) as chelators. Two different concentrations of the chelators were studied for enhancing the uptake and translocation of Cd, Cr, and Ni from a silty-clay loam soil. When 1.0 g/kg CA was used, the highest total metal uptake was only 0.65 mg. Increasing the CA concentration posed a severe phytotoxicity to both cultivars as evidenced by stunted growth and diminished uptake rates. Decreasing the CA concentration to 0.1 and 0.3 g/kg yielded results that were not statistically different from the control. EDTA at a concentration of 0.1 g/kg yielded the best results for both cultivars achieving a total metal uptake of {approx}0.73 mg compared to {approx}0.40 mg when EDTA was present at 0.3 g/kg.

  9. Simultaneous removal of As, Cd, Cr, Cu, Ni and Zn from stormwater using high-efficiency industrial sorbents: Effect of pH, contact time and humic acid

    DEFF Research Database (Denmark)

    Genc-Fuhrman, Hülya; Mikkelsen, Peter Steen; Ledin, Anna

    2016-01-01

    The effect of contact time, solution pH, and the presence of humic acid (HA) on the combined removal of As, Cd, Cr, Cu, Ni and Zn is investigated in batch tests using alumina, granulated activated carbon (GAC), and bauxsol coated sand (BCS) as sorbents. It is found that the equilibrium time for Cd...... of natural organic acids during the pollen season in spring or during defoliation in autumn and early winter, and during mixing of runoff with snowmelt having a low pH....

  10. Phytoremediation of Cd, Cr, Cu, Mn, Fe, Ni, Pb and Zn from aqueous solution using Phragmites cummunis, Typha angustifolia and Cyperus esculentus.

    Science.gov (United States)

    Chandra, Ram; Yadav, Sangeeta

    2011-07-01

    A comparative bioaccumulation pattern and ultra structural changes were studied in Phragmites cummunis, Typha angustifolia and Cyperus esculentus in mixed metals solution of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn). P. cummunis was observed to be a shoot accumulator for Cr, Fe, Mn, Ni, Pb, and Zn. However, T. angustifolia was found to be a root accumulator for Cd, Cr, Cu, Fe, Ni and Pb. In addition, C. esculentus also accumulated most of the tested heavy metals in the roots, while Mn and Fe were translocated up to leaves. Further, the long term metal treatment showed maximum accumulation of all heavy metals in P. cummunis followed by T. angustifolia and C. esculentus. Among heavy metals, Fe was accumulated maximum, i.e., >1000 microg g(-1) by all three plants. Simultaneously, the adverse effects on biochemical parameters were noted earlier in C. esculentus than T. angustifolia and P. cummunis. Ultra structural observation showed the cellular changes in wetland plants after longer exposure. Results revealed that P. cummunis and T. angustifolia had more potential for tested metals than C. esculentus. This study established that these wetland plants could be used for heavy metals phytoremediation from metal containing industrial wastewater. PMID:21972504

  11. Drinking water interlaboratory ring test. Part IV. Results of some cationic analytes. Al, Zn, Cd, Cr, Pb, Ni, Mn, Fe, Cu and V; Circuito interlaboratorio Unichim sulle acque potabili. Parte IV. Risultati di alcuni cationi metallici. Al, Zn, Cd, Co, Cr, Pb, Ni, Mn, Fe, Cu e V

    Energy Technology Data Exchange (ETDEWEB)

    Cavaterra, E.; Divo, C.; Bottazzini, N. [Unichim, Milan (Italy); Alava, F. [Bergamo Ambiente e Servizi, Bergamo (Italy); Bettinelli, M. [Electric Power Production Company, Piacenza (Italy); Bonfiglioli, F. [Azienda Mediterranea Gas e Acqua SpA, Genoa (Italy)

    2002-01-01

    In this paper results of statistical treatment of experimental data obtained in some cycles of an interlaboratory ring test of content of Al, Zn, Cd, Co, Cr, Pb, Ni, Mn, Fe, Cu and V in drinking water are reported. Means, variances and parameters of precision and accuracy of some analytical techniques and methods employed by laboratories participating to the ring test will be reported and discussed. [Italian] Nel presente lavoro vengono riportati i risultati dell'elaborazione statistica dei dati sperimentali ottenuti in alcuni cicli del circuito interlaboratorio e relativi ai seguenti cationi metallici: Al, Zn, Cd, Co, Cr, Pb, Ni, Mn, Fe, Cu e V. Vengono riportati e discussi i valori medi e la varianza ed infine i dati di accuratezza e precisione delle tecniche o metodi d'analisi impiegati dai laboratori partecipanti al circuito.

  12. Electronic and magnetic properties of metal diiodides MI2 (M=V, Cr, Mn, Fe, Co, Ni and Cd) from 129I Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    The hyperfine interaction parameters at the iodine site in various metal diiodides (M=Cr, V, Mn, Fe, Co, Ni, Cd) were measured using the 27.8keV Moessbauer transition in 129I. Charge densities in the valence orbitals are deduced from an interpretation of isomer shift and quadrupole constant values. Magnetic hyperfine interactions transferred at the originally diamagnetic iodine ion in the magnetically ordered phases of the compounds allow one to determine the unpaired spin densities in the valence orbitals. Information relating to the magnetic structures are obtained from the number and intensities of magnetically nonequivalent sites and from the relative orientation between the transferred field and the electric field gradient axes. The Moessbauer spectra of 129Xe impurities created by β- decay of 129I in the NiI2 lattice reveal the absence of bonding of xenon atoms in this matrix

  13. Effect of EDTA, EDDS, NTA and citric acid on electrokinetic remediation of As, Cd, Cr, Cu, Ni, Pb and Zn contaminated dredged marine sediment.

    Science.gov (United States)

    Song, Yue; Ammami, Mohamed-Tahar; Benamar, Ahmed; Mezazigh, Salim; Wang, Huaqing

    2016-06-01

    In recent years, electrokinetic (EK) remediation method has been widely considered to remove metal pollutants from contaminated dredged sediments. Chelating agents are used as electrolyte solutions to increase metal mobility. This study aims to investigate heavy metal (HM) (As, Cd, Cr, Cu, Ni, Pb and Zn) mobility by assessing the effect of different chelating agents (ethylenediaminetetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS), nitrilotriacetic acid (NTA) or citric acid (CA)) in enhancing EK remediation efficiency. The results show that, for the same concentration (0.1 mol L(-1)), EDTA is more suitable to enhance removal of Ni (52.8 %), Pb (60.1 %) and Zn (34.9 %). EDDS provides effectiveness to increase Cu removal efficiency (52 %), while EDTA and EDDS have a similar enhancement removal effect on As EK remediation (30.5∼31.3 %). CA is more suitable to enhance Cd removal (40.2 %). Similar Cr removal efficiency was provided by EK remediation tests (35.6∼43.5 %). In the migration of metal-chelate complexes being directed towards the anode, metals are accumulated in the middle sections of the sediment matrix for the tests performed with EDTA, NTA and CA. But, low accumulation of metal contamination in the sediment was observed in the test using EDDS. PMID:26782321

  14. Density of Liquid Ni-Cr Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The density of liquid Ni-Cr alloy was measured by a modified sessile drop method. The density of liquid Ni-Cr alloywas found to decrease with increasing temperature and Cr concentration in the alloy. The molar volume of liquidNi-Cr alloy increases with increasing the Cr concentration in the alloy. The molar volume of Ni-Cr alloy determinedin the present work shows a positive deviation from the linear molar volume.

  15. Evaluation of heavy metals (Cr, Fe, Ni, Cu, Zn, Cd, Pb and Hg) in water, sediments and water lily (Eichornia crassipes) from Jose Antonio Alzate dam

    International Nuclear Information System (INIS)

    Water, sediments and water lily (Eichornia crassipes) from the Jose Antonio Alzate Dam were analyzed in order to determine concentrations of chromium, iron, nickel, copper, zinc, cadmium, lead and mercury. Mercury, lead, chromium and iron were found in concentrations above permissible limits in water, and in high concentrations in sediments. Cadmium, nickel, copper and zinc never were found in concentrations above permissible limits in water. The highest concentrations of heavy metals in water lily were found in the root. Accumulation factors decreased in the following order: Zn> Cr> Fe> Ni> Cu> Pb> Hg and Cd. Statistical differences (α < 0.5) between the collection samples dates was observed. High correlations between metals concentrations in superficial water, sediment and water hyacinth were also observed. These correlations could indicate that the heavy metals studied here, are originated from a natural source such as sediments or from an industrial source. (Author)

  16. Time saving modified BCR sequential extraction procedure for the fraction of Cd, Cr, Cu, Ni, Pb and Zn in sediment samples of polluted lake

    International Nuclear Information System (INIS)

    The mobility, availability and persistence of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in contaminated lake sediment samples were evaluated by means of sequential extraction scheme, proposed by the Community Bureau of Reference protocol (BCR). The metal content in the extracts was measured by atomic absorption spectrometry. The precision and accuracy of the proposed procedure were evaluated by using a certified reference material BCR 701. The maximum recoveries for heavy metals (HMs) were observed for all three steps of BCR protocol at 32 h total shaking period instead of previously reported 51 h, with p > 0.05. The lixiviation tests (DIN 38414-S4) were used to evaluate the leaching of HMs from sediment samples and it was observed that levels of water extractable HMs were low as compared to those values obtained by acid-soluble fraction of the BCR protocol

  17. Associations between standardized school performance tests and mixtures of Pb, Zn, Cd, Ni, Mn, Cu, Cr, Co, and V in community soils of New Orleans

    International Nuclear Information System (INIS)

    In New Orleans a strong inverse association was previously identified between community soil lead and 4th grade school performance. This study extends the association to zinc, cadmium, nickel, manganese, copper, chromium, cobalt, and vanadium in community soil and their comparative effects on 4th grade school performance. Adjusting for poverty, food security, racial composition, and teacher-student ratios, regression results show that soil metals variously reduce and compress student scores. Soil metals account for 22%–24% while food insecurity accounts for 29%–37% of variation in school performance. The impact on grade point averages were Ni > Co > Mn > Cu ∼CrCd > Zn > Pb, but metals are mixtures in soils. The quantities of soil metal mixtures vary widely across the city with the largest totals in the inner city and smallest totals in the outer city. School grade point averages are lowest where the soil metal mixtures and food insecurity are highest. - Highlights: ► Mixtures of metals vary; largest totals in the inner city and lowest in the outer city. ► An inverse association between soil Pb and 4th grade school performance is known. ► Assuming the same exposure pathway, multiple metals are compared to performance. ► Soil metals account for 22%–24% of variation in school test performance. ► Soil metal plus food insecurity accounts for 54% of explained variance. - Controlling for potential confounding variables, the accumulation of metals (Pb, Zn, Cd, Ni, Mn, Cu, Cr, and Co) in neighborhood soils is significantly negatively associated with 4th grade school performance on standardized tests in New Orleans.

  18. Solid-liquid-solid extraction of heavy metals (Cr, Cu, Cd, Ni and Pb) in aqueous systems of zeolite-sewage sludge

    International Nuclear Information System (INIS)

    This paper presents results of kinetic and equilibrium studies of the removal of heavy metals (Cr, Cu, Cd, Ni and Pb) from the sewage sludge using a new technique of solid-liquid-solid extraction with the adsorption-diffusion column filled by the zeolite. The metal extraction onto the zeolite from aqueous solution of the clinoptilolite and the sludge composition is characterized by three stages: intensive extraction, inversion and stabilization with the moderate extraction increase. Addition of 25% of the zeolite provides extraction efficiency of cadmium and lead of about 84%, chromium, copper and nickel of 66%, 61% and 50%, respectively. The estimated values of Gibbs free energy change ΔG show that the metals extraction by the clinoptilolite may be considered as a physical adsorption. The negative values of ΔG testify to an exothermic nature of the process. The difference between energetic potentials of the components is a driving force of the metal redistribution in the system 'clinoptilolite-water-sludge'

  19. Assessment of heavy metals/metalloid (As, Pb, Cd, Ni, Zn, Cr, Cu, Mn) concentrations in edible fish species tissue in the Pearl River Delta (PRD), China.

    Science.gov (United States)

    Leung, H M; Leung, A O W; Wang, H S; Ma, K K; Liang, Y; Ho, K C; Cheung, K C; Tohidi, F; Yung, K K L

    2014-01-15

    The major aim of this study was to investigate heavy metal content of edible fish in the PRD. Eleven species of fish (consisting of 711 individuals) [catfish (Clarias fuscus), tilapia (Oreochromis mossambicus), grass carp (Ctenopharyngodon idellus), bighead carp (Aristichthys nobilis), mandarin fish (Siniperca kneri), snakehead (Channa asiatiea), black bass (Micropterus salmoides), mangrove snapper (Lutjanus griseus), star snapper (Lutjanu stellatus), snubnose pompano (Trachinotus blochii) and orange-spotted grouper (Epinephelus coioides)] were collected for the analyses of heavy metals. Overall concentrations (mg/kg, ww) in the fish muscles were: As (0.03-1.53), Pb (0.03-8.62), Cd (0.02-0.06), Ni (0.44-9.75), Zn (15.7-29.5), Cr (0.22-0.65), Cu (0.79-2.26), Mn (0.82-6.91). Significant level of Pb were found in tilapia at all locations. It is recommended that heavy metal concentrations in different fish species must be determined on a regular basis in the future so as to reduce human health risks from acute and chronic food intoxication. PMID:24239097

  20. Concentration of heavy metals, Mn, Fe, Ni, Pb, Cr and Cd in bottom sediments of the Outer Songkhla Lake deposited between the year B.E. 2520-2538

    Directory of Open Access Journals (Sweden)

    Bhongsuwan, T.

    2002-01-01

    Full Text Available The study aimed to analyse the heavy metals Mn, Fe, Ni, Pb, Cr and Cd in 20 bottom sedimentsamples from 0 - 9 cm depth collected in 4 sites in the Outer Songkhla Lake. These sediment samples were deposited during the year B.E. 2520-2538 according to the Cs-137 dating. Total acid digestion was used to totally dissolve the samples using aqua regia and hydrofluoric acids. A quality control was performed by digesting the certified reference material IAEA SL-1 (lake sediment. Percent recoveries of selected heavy metals were between 79.96 (Ni and 99.26 (Cr. Concentrations of Mn, Fe, Ni, Pb and Cr in the sediment samples were in ranges 368-756, 21014-36683, 1.1-16.7, 24.5-59.8 and 30.1-67.5 mg/kg, respectively.Cadmium was non-detectable but calculated to be less than 2.5 mg/kg in all samples. Result showed thatMn has significantly increased between the depth 9-0 cm (the deposition years B.E. 2520-2538, while Fe,Ni, Pb and Cr had not changed significantly. It was concluded that Mn, Fe, Ni and Cr were still in low concentration comparable to those of sediments in several remote lakes worldwide both in Europe and America. Only Pb concentration was found to be higher than that in remote lakes worldwide. Iron was found to be the best conservative element in the outer Songkhla Lake. Regional anomaly criteria showed that Mn, Ni, Pband Cr in most samples were within the natural geochemical population except for Ni in one sample of coreU, which was considered to be a regional anomaly. Geoaccumulation index calculated in comparison with heavy metal concentration in average shale showed that sediment samples of the outer Songkhla Lake were not polluted by Mn, Fe, Ni, Cr at any site, and were unpolluted/moderately polluted for Pb at site T. Analysis of the magnetic susceptibility and the heavy metal contents in sediments showed no clear relation between them.

  1. 复合污染下Cu、Cr、Ni和Cd在水稻植株中的富集特征%Enrichment of Heavy Metals in Rice under Combined Pollution of Cu, Cr, Ni and Cd

    Institute of Scientific and Technical Information of China (English)

    林华; 张学洪; 梁延鹏; 刘杰; 黄海涛

    2014-01-01

    掌握水稻对污染土壤中重金属的吸收和富集特征,为科学认识水稻中重金属的残留问题、健康风险提供理论依据。采用田间试验,研究了4个不同处理量Cu、Cr、Ni、Cd复合污染下水稻的富集特征及其随生育期的变化规律。结果表明,重金属在水稻植株各部位中吸收富集系数的大小依次为:Cd>Cu>Ni>Cr,根部重金属吸收富集系数是地上各部位的吸收富集系数的2~100倍。各重金属在水稻植株不同部位的积累分布明显不同,成熟期水稻植株中Cu在水稻不同部位的质量分数为根>茎≥叶>米粒>谷壳,Ni的分布规律为根>叶>茎>米粒>谷壳,Cr的分布规律为根>叶>谷壳≥茎>米粒,Cd的分布规律为根>茎>叶>米粒>谷壳;且随着重金属处理量的增加,水稻植株不同部位的重金属质量分数也呈上升趋势。成熟期米粒中Cu、Ni、Cr和Cd的质量分数范围分别为:4.50~6.19、1.86~4.63、0.72~0.76和0.08~0.39 mg·kg-1,与无公害食品标准(GB15199-94、GBT2762-2005)相比,米粒中Cu和Cr的质量分数均未超标,而Ni和Cd(Cd高剂量处理时)的质量分数均超标,存在食用安全风险。重金属在水稻植株不同部位的质量分数随生育期均呈现先升后降的趋势,灌浆中期达到最大,而到成熟期又明显降低。不同重金属在水稻植株中的富集能力和分布规律均呈现明显差异,不同生育期水稻植株中重金属的质量分数明显不同但其质量分数变化呈明显规律性。%Absorption and Accumulation Characteristics of heavy metals by rice in the heavy-metal polluted soils were analyzed to provide theoretical basis for recognizing heavy metals residue in rice, health risk. The enrichment characteristics and changes of Cu, Cr, Ni and Cd integrated effects in rice during their growing were studied through field experiment. The results showed that the enrichment sequence of four heavy metals

  2. Evaluation of the air quality regarding total suspended particles and heavy metals (Pb, Cd, Ni, Cu, Cr) in the Hermosillo city, Sonora, Mexico, during a yearly period; Evaluacion de la calidad del aire respecto de particulas suspendidas totales y metales pesados (Pb, Cd, Ni, Cu, Cr) en la Ciudad de Hermosillo, Sonora, Mexico, durante un periodo anual

    Energy Technology Data Exchange (ETDEWEB)

    Cruz C, M. E.; Quintero N, M. [Universidad Autonoma de Baja California, Instituto de Ingenieria, Campus Mexicali, Calle de la Normal s/n, y Blvd. Benito Juarez, Col. Insurgentes Este, Mexicali, Baja California (Mexico); Gomez A, A.; Varela S, J., E-mail: martincruzcampas@hotmail.com [Universidad de Sonora, Departamento de Ingenieria Quimica y Metalurgia, Blvd. Rosales y Luis Ensina s/n, Edificio 5B, Col. Centro, 83000 Hermosillo, Sonora (Mexico)

    2013-07-01

    In the present study, the air quality of the city of Hermosillo, Sonora, Mexico was assessed considering total suspended particulates (tsp) and heavy metals (Pb, Cd, Ni, Cu, Cr) from June 2001 through May 2002 in three monitoring sites Centro (Mazon), Nor este (CESUES) and Noroeste (CBTIS). The filter-samples used for that purpose were provided by the Air Quality Evaluation and Improvement Program (PEMCA) of the municipality of Hermosillo. The sampling method was based on high volume sampling frequency set every 6 days with non-simultaneous sampling among the three sampling sites. Filters were dissolved for metal determination by acidic-extraction, and then analyzed by flame atomic absorption spectrophotometry. Results indicate that tsp concentrations at Centro and Noroeste sites were frequently higher than the maximum daily permissible level (260 {mu}g/m{sup 3}), while in the three sites the annual average was higher than the maximum annual permissible level (75 {mu}g/m{sup 3}) both established in the standard NOM-024-Ssa-1993 (Ssa 1994a). According to the Air Quality Standard Index (US EPA 1992a), used in Mexico by Air Quality Metropolitan Index (IMECA) the results indicate that the air quality in the city of Hermosillo regarding tsp was placed between no satisfactory and poor. In regard to heavy metals (Pb, Cd, Ni, Cu, Cr), concentrations detected were below the maximum permissible levels and/or criteria taking into account the standard NOM-026-Ssa-1993 (Ssa 1994b), the Who criterion (2000), the European Union criterion (Cec 2003), and the European Environmental Agency criteria (EEA 2004). Such findings would mean that airborne metals are of no concern; however, air quality is still classified as no satisfactory due to high particulate matter concentrations. Keeping air quality parameters monitoring is recommended in order to get extensive data for use in risk studies of air quality and health (morbidity/mortality), as well as topographic conditions

  3. Solidification shrinkage of Ni-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Feng [Materials Interfacial Physical-Chemistry Research Institute, Chongqing Institute of Technology, No. 4 Xingsheng Road, Yangjiaping, Chongqing 400050 (China); Yang Renhui [Materials Interfacial Physical-Chemistry Research Institute, Chongqing Institute of Technology, No. 4 Xingsheng Road, Yangjiaping, Chongqing 400050 (China)]. E-mail: yangrh2004@21cn.com; Fang Liang [Department of Applied Physics, Chongqing University, No. 174 Shazhong Road, Shapingba, Chongqing 400044 (China); Zhang Chi [Materials Interfacial Physical-Chemistry Research Institute, Chongqing Institute of Technology, No. 4 Xingsheng Road, Yangjiaping, Chongqing 400050 (China)

    2006-07-25

    Ni-Cr superalloy is widely used in casting of critical components in gas-turbine engines. Because of the significant change in density of alloy in mushy state, porosity is likely to arise in the alloy parts due to the solidification shrinkage. On the other hand, because Ni-Cr alloy is very hard and difficult to be machined, the net-shape casting of the alloy is a cheap process. Therefore, it is essential to measure the solidification shrinkage of mushy alloy for obtaining low-cost net-shape casting ingot without inner porosity. However, there have been a few reports on the solidification shrinkage of the liquid Ni-Cr alloy. In this work, the solidification shrinkage of Ni-Cr alloy was calculated by measuring its density using modified sessile drop method. It has been found that, for Ni-(0-24.53)% Cr alloys, the solidification shrinkage value fluctuates in the range of 0.91-2.02% and it tends to increase with increasing Cr concentration in 0-10% Cr. However, for Cr concentration more than 10%, the solidification shrinkage holds on a certain value of 2.00%.

  4. Electronic structure and band alignments of ZnTe/CrTe(0 0 1), CdSe/CrTe(0 0 1) and CdTe/CrTe(0 0 1) interfaces

    Indian Academy of Sciences (India)

    F Ahmadian; R Zare

    2011-08-01

    All-electron full potential calculations based on spin density functional theory were performed to study cubic zincblende (ZB) and hexagonal NiAs structures of bulk CrTe and ZnTe/CrTe(0 0 1), CdTe/CrTe(0 0 1) and CdSe/CrTe(0 0 1) interfaces. The lattice mismatch effect in ZB CrTe and magnetic properties of CrTe in the ideal ZB CrTe structure were investigated. The band alignment properties of the ZnTe/CrTe(0 0 1), CdTe/CrTe(0 0 1) and CdSe/CrTe(0 0 1) interfaces were computed and a rather large minority valence band offset of about 1.09 eV was observed in ZnTe/CrTe(0 0 1) heterojunction. Also in the CdTe/CrTe(0 0 1) and CdSe/CrTe(0 0 1) interfaces, the conduction band minimum of minority spin in CrTe was above the conduction band minimum of CdTe and CdSe and so the majority spin electrons could be directly injected to both semiconductors, indicating the possibility of highly efficient spin injection into the CdSe and CdTe semiconductors.

  5. The influence of metal speciation in combustion waste on the efficiency of Cu, Pb, Zn, Cd, Ni and Cr bioleaching in a mixed culture of sulfur-oxidizing and biosurfactant-producing bacteria.

    Science.gov (United States)

    Karwowska, Ewa; Wojtkowska, Małgorzata; Andrzejewska, Dorota

    2015-12-15

    Metal leachability from ash and combustion slag is related to the physico-chemical properties, including their speciation in the waste. Metals speciation is an important factor that influences the efficiency of metal bioleaching from combustion wastes in a mixed culture of acidophilic and biosurfactant-producing bacteria. It was observed that individual metals tended to occur in different fractions, which reflects their susceptibility to bioleaching. Cr and Ni were readily removed from wastes when present with a high fraction bound to carbonates. Cd and Pb where not effectively bioleached when present in high amounts in a fraction bound to organic matter. The best bioleaching results were obtained for power plant slag, which had a high metal content in the exchangeable, bound to carbonates and bound to Fe and Mg oxides fractions- the metal recovery percentage for Zn, Cu and Ni from this waste exceeded 90%. PMID:26073519

  6. Synthesis of amino functionalized magnetic graphenes composite material and its application to remove Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) from contaminated water.

    Science.gov (United States)

    Guo, Xiaoyao; Du, Bin; Wei, Qin; Yang, Jian; Hu, Lihua; Yan, Liangguo; Xu, Weiying

    2014-08-15

    In the present study, a kind of graphenes magnetic material (Fe3O4-GS) was prepared by compositing graphene sheet with ferroferric oxide, and shown to be effective for removing Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) ions from aqueous solution. The synthesized sorbent was characterized by SEM, TEM, FTIR, XRD, XPS and BET, respectively. The pHZPC value of the sorbent was estimated to be 3.5 by alkaline-titration methods. Fe3O4-GS can be simply recovered from water with magnetic separation at low magnetic field within one minute. The sorption capacities of the metals were 17.29, 27.95, 23.03, 27.83 and 22.07 mg g(-1) for Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II), respectively. Kinetic data showed good correlation with pseudo-second-order equation and the Freundlich model was found to fit for the isotherm data of all the heavy metal ions. It was found that the metals sorption was accomplished mainly via chelation or ion exchange. The results of thermodynamic studies illustrate that the adsorption process was endothermic and spontaneous in nature.

  7. Corrosion performance of bi-layer Ni/Cr2C3-NiCr HVAF thermal spray coating

    Science.gov (United States)

    Sadeghimeresht, E.; Markocsan, N.; Nylén, P.; Björklund, S.

    2016-04-01

    The corrosion behavior of three HVAF thermal spray coating systems (A: single-layer Ni, B: single-layer Cr2C3-NiCr coatings, and C: bi-layer Ni/Cr2C3-NiCr coating) was comparatively studied using immersion, salt spray, and electrochemical tests. Polarization and EIS results showed that the corrosion behavior of Cr2C3-NiCr coatings in 3.5 wt.% NaCl solution was significantly improved by adding the intermediate layer of Ni. It was illustrated that the polarization resistance of the bi-layer Ni/Cr2C3-NiCr and single-layer Cr2C3-NiCr coatings were around 194 and 38 kΩ cm2, respectively. Microstructure analysis revealed that the bond coating successfully prevented the corrosion propagation toward the coating.

  8. Standard Specification for Electric Fusion-Welded Ni-Cr-Co-Mo Alloy (UNS N06617), Ni-Fe-Cr-Si Alloys (UNS N08330 and UNS N08332), Ni-Cr-Fe-Al Alloy (UNS N06603), Ni-Cr-Fe Alloy (UNS N06025), and Ni-Cr-Fe-Si Alloy (UNS N06045) Pipe

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2014-01-01

    Standard Specification for Electric Fusion-Welded Ni-Cr-Co-Mo Alloy (UNS N06617), Ni-Fe-Cr-Si Alloys (UNS N08330 and UNS N08332), Ni-Cr-Fe-Al Alloy (UNS N06603), Ni-Cr-Fe Alloy (UNS N06025), and Ni-Cr-Fe-Si Alloy (UNS N06045) Pipe

  9. Estudio del equilibrio y cinética de adsorción de Cd(II, Ni(II y Cr(VI usando Quitosano y Quitosano modificado con cobre

    Directory of Open Access Journals (Sweden)

    M. Benavente

    2013-04-01

    Full Text Available En este trabajo, se estudió el equilibrio y la cinética de adsorción de Cd(II, Ni(II en quitosano y Cr(VI en quitosano modificado con cobre. Para ello, soluciones de iones metálicos a diferentes concentraciones, fueron puestas en contacto con el adsorbente y se agitaron por un período de 3 – 4 h. Al final del proceso, las muestras fueron analizadas en un espectrómetro de absorción atómica. Los datos experimentales del equilibrio de adsorción de los iones metálicos fueron evaluados aplicando las isotermas de Langmuir y Freundlich; mientras los datos cinéticos fueron evaluados utilizando los modelos cinéticos de pseudo-primer orden y pseudo-segundo orden. Los resultados del proceso demostraron que los iones fueron eficazmente adsorbidos por el quitosano (Cd y Ni y por el Cu-quitosano (Cr. Además, se comprobó que los datos experimentales del equilibrio de adsorción de Cr(VI y Ni(II se ajustan al modelo de Langmuir; mientras que los datos experimentales del Cd(II fueron mejor ajustados por el modelo de Freundlich. Mediante el uso de la isoterma de Langmuir se determinó la capacidad máxima de adsorción de cromo (29.7 mg/g Cu-quitosano, cadmio (102.0 mg/g quitosano y níquel (83.31 mg/g quitosano. Los resultados de la cinética de adsorción de los iones metálicos mostraron que los datos experimentales fueron mejor ajustados por el modelo de pseudo-segundo orden; es decir, el paso limitante en la velocidad es la reacción de adsorción y no la transferencia de masa.

  10. Chemometric evaluation of Cd, Co, Cr, Cu, Ni (inductively coupled plasma optical emission spectrometry) and Pb (graphite furnace atomic absorption spectrometry) concentrations in lipstick samples intended to be used by adults and children.

    Science.gov (United States)

    Batista, Érica Ferreira; Augusto, Amanda dos Santos; Pereira-Filho, Edenir Rodrigues

    2016-04-01

    A method was developed for determining the concentrations of Cd, Co, Cr, Cu, Ni and Pb in lipstick samples intended to be used by adults and children using inductively coupled plasma optical emission spectrometry (ICP OES) and graphite furnace atomic absorption spectrometry (GF AAS) after treatment with dilute HNO3 and hot block. The combination of fractional factorial design and Desirability function was used to evaluate the ICP OES operational parameters and the regression models using Central Composite and Doehlert designs were calculated to stablish the best working condition for all analytes. Seventeen lipstick samples manufactured in different countries with different colors and brands were analyzed. Some samples contained high concentrations of toxic elements, such as Cr and Pb, which are carcinogenic and cause allergic and eczematous dermatitis. The maximum concentration detected was higher than the permissible safe limits for human use, and the samples containing these high metal concentrations were intended for use by children. Principal component analysis (PCA) was used as a chemometrics tool for exploratory analysis to observe the similarities between samples relative to the metal concentrations (a correlation between Cd and Pb was observed). PMID:26838401

  11. 应用 SHIME 模型研究肠道微生物对土壤中镉、铬、镍生物可给性的影响%Effects of Human Gut Microbiota on Bioaccessibility of Soil Cd, Cr and Ni Using SHIME Model

    Institute of Scientific and Technical Information of China (English)

    尹乃毅; 都慧丽; 张震南; 蔡晓琳; 李泽姣; 孙国新; 崔岩山

    2016-01-01

    为了研究人体肠道微生物对土壤中 Cd、 Cr、 Ni 生物可给性的影响.本文采集我国一些地区的5种土壤,利用 in vitro 方法(PBET 和 SHIME 联用)研究了这些土壤中 Cd、 Cr、 Ni 在胃、小肠、结肠阶段的生物可给性及其对人体的健康风险.结果表明,土壤中 Cd、 Cr、 Ni 在胃阶段的生物可给性分别为4.3%~94.0%、6.4%~21.6%、11.3%~47.3%;小肠阶段,土壤中 Cr和 Ni 的生物可给性与胃阶段一致或有一定升高,但 Cd 的生物可给性降低了1.4~1.6倍(土壤2除外);胃肠阶段,Cd 的平均生物可给性较高,而 Cr 的较低.结肠阶段,土壤中 CrNi 的生物可给性均升高,是小肠阶段的1.3~2.4倍和1.0~2.1倍,分别达到了17.6%~38.7%和25.4%~56.0%;而 Cd 的生物可给性也升高(土壤3和4除外); Ni 的平均生物可给性最高.由此可见,肠道微生物可以促进土壤中 Cd、 Cr、 Ni 的溶出释放,提高了三者的生物可给性,可能增大了人体的健康风险.%The influence of human gut micobiota on bioaccessibilities of soil Cd, Cr, and Ni were investigated in this study. Five soil samples were collected from some sites of China, and the bioaccessibilities of soil Cd, Cr, and Ni in the gastric, small intestinal, and colon phases were determined using the PBET method (physiologically based extraction test) combined with SHIME model (simulator of human intestinal microbial ecosystem). The results showed that the bioaccessibilities of Cd, Cr, and Ni in the gastric phase were 4. 3% -94. 0% , 6. 4% -21. 6% , and 11. 3% -47. 3% , respectively. In the small intestinal phase, the bioaccessibilities of Cr and Ni were either congruent or slightly increased, while for Cd, the values were reduced by 1. 4-1. 6 folds except for soil 2. In the gastric and small intestinal phases, the mean bioaccessibility of Cd was higher but that of Cr was lower. In the colon phase, the bioaccessibilities of Cr and Ni were 1. 3-2. 4 and

  12. Synthesis of amino functionalized magnetic graphenes composite material and its application to remove Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) from contaminated water

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiaoyao [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Du, Bin, E-mail: dubin61@gmail.com [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Wei, Qin, E-mail: sdjndxwq@163.com [School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Yang, Jian [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Hu, Lihua [School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Yan, Liangguo; Xu, Weiying [School of Resources and Environment, University of Jinan, Jinan 250022 (China)

    2014-08-15

    Highlights: • Graphenes magnetic composite nanoparticles (Fe{sub 3}O{sub 4}-GS) were used to adsorb metal ions. • The adsorption of metal ions onto Fe{sub 3}O{sub 4}-GS could be well interpreted by the Freundlich equation. • The adsorption of metal ions onto Fe{sub 3}O{sub 4}-GS fit pseudo-second order kinetic model. • Thermodynamic studies illustrated that the adsorption process was endothermic and spontaneous in nature. - Abstract: In the present study, a kind of graphenes magnetic material (Fe{sub 3}O{sub 4}-GS) was prepared by compositing graphene sheet with ferroferric oxide, and shown to be effictive for removing Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) ions from aqueous solution. The synthesized sorbent was characterized by SEM, TEM, FTIR, XRD, XPS and BET, respectively. The pH{sub ZPC} value of the sorbent was estimated to be 3.5 by alkaline-titration methods. Fe{sub 3}O{sub 4}-GS can be simply recovered from water with magnetic separation at low magnetic field within one minute. The sorption capacities of the metals were 17.29, 27.95, 23.03, 27.83 and 22.07 mg g{sup −1} for Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II), respectively. Kinetic data showed good correlation with pseudo-second-order equation and the Freundlich model was found to fit for the isotherm data of all the heavy metal ions. It was found that the metals sorption was accomplished mainly via chelation or ion exchange. The results of thermodynamic studies illustrate that the adsorption process was endothermic and spontaneous in nature.

  13. 巨磁电阻材料A0.05Co0.95Cr2S4(A=Zn、Ni、Cd、Fe)的输运行为及磁性能研究%Transport Behavior and Magnetism of Colossal Magnetoresistance Materials A0.05Co0.95Cr2S4 (A=Zn, Ni, Cd, Fe)

    Institute of Scientific and Technical Information of China (English)

    卢晓羽; 贾楠; 方必军; 杨昭荣; 张裕恒

    2016-01-01

    过渡金属尖晶石型硫化物具有包括超巨磁电阻(CMR)效应在内的多种物理性能,其 CMR 效应机理的研究对开发巨磁电阻材料有重要价值。目前,铬基硫族尖晶石的CMR效应尚未深入研究。本论文通过固相反应法制备A0.05Co0.95Cr2S4(A=Zn、Ni、Cd、Fe)样品,研究磁性和非磁性元素掺杂对CoCr2S4晶体结构和磁性能的影响。XRD检测表明,掺杂的A0.05Co0.95Cr2S4(A=Zn、Ni、Cd、Fe)均呈现纯的尖晶石结构,掺杂导致的晶胞参数变化与掺杂元素的离子半径成比例。磁电阻测定表明A0.05Co0.95Cr2S4(A=Zn、Ni、Fe)均具有巨磁电阻效应。掺杂削弱了铁磁相互作用,导致A0.05Co0.95Cr2S4(A=Zn、Ni、Cd、Fe)的居里温度TC降低。在0.01 T下, A0.05Co0.95Cr2S4(A=Zn、Ni、Cd、Fe)的零场冷却(ZFC)和加场冷却(FC)曲线均呈现磁性不可逆现象。A0.05Co0.95Cr2S4(A=Zn、Ni、Cd、Fe)呈现典型的亚铁磁性磁滞回线,其中Zn0.05Co0.95Cr2S4的矫顽场最大。%Spinel-type transition metal sulfides possess various super physical properties including colossal magnetore-sistance (CMR). The research of the mechanism of the CMR effect is of great value for the development of the CMR sul-fide materials, whereas the CMR effect of the spinel chrome-based sulfides is unclear up till now. The A0.05Co0.95Cr2S4 (A=Zn, Ni, Cd, Fe) samples were prepared by solid-state reaction method. Their effects of magnetic and non-magnetic metal elements on crystal structure and magnetic properties of CoCr2S4 after doping were studied. XRD measurement shows that the doped A0.05Co0.95Cr2S4 (A=Zn, Ni, Cd, Fe) samples exhibit pure spinel structure, in which their crystal cell parameters increase proportional to the ionic radius of the doping elements. Magnetoresistance measurement shows that all the samples exhibit giant magnetoresistance effect. Doping weakens the ferromagnetic interaction, which leads to the de-crease ofTC of A0.05Co0.95Cr2S4 (A

  14. Internal chlorination of Ni-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Berztiss, D.; Hennesen, K.; Grabke, H.J. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)

    1998-12-31

    In contrast to internal oxidation, sulfidation and carburization, very little information is available regarding internal chlorination, especially diffusion of chlorine in metallic alloys. This paper describes results of experiments on Ni-Cr alloys (<10 wt% Cr) exposed in an atmosphere containing radioactive HCl. The diffusion of chlorine in the alloy can be determined by measurement of residual {beta}-activity from the sample surface. Successively thin layers (0.5-10 {mu}m) of the alloy were removed by lapping and the surface activity was measured to obtain a depth profile. Both single and polycrystalline materials were tested. Through this work it should be determined if there is in fact solubility and diffusion of chlorine in Ni-based alloys as some authors have proposed or if the ingress of chlorine is mainly a grain boundary phenomenon. (orig.)

  15. EPR spectroscopy of a family of Cr(III) 7M(II) (M = Cd, Zn, Mn, Ni) "wheels": studies of isostructural compounds with different spin ground states

    DEFF Research Database (Denmark)

    Piligkos, Stergios; Weihe, Høgni; Bill, Eckhard;

    2009-01-01

    Spinning wheels: The presented highly resolved multifrequency continuous wave EPR spectra (e.g., see figure) of the heterooctametalic "wheels" Cr(7)M provide rare examples of high nuclearity polymetallic systems where detailed information on the spin-Hamiltonian parameters of the ground and excit...... to 10(5) by use of the Davidson algorithm. We show that transferability of spin-Hamiltonian parameters across complexes of the Cr(7)M family is possible and that the spin-Hamiltonian parameters of Cr(7)M do not have sharply defined values, but are rather distributed around a mean value....

  16. Creep behavior of plasma sprayed NiCr and NiCrAl coating-based systems

    Institute of Scientific and Technical Information of China (English)

    Xiancheng ZHANG; Changjun LIU; Fuzhen XUAN; Zhengdong WANG; Shan-Tung TU

    2011-01-01

    The creep behavior of the plasma sprayed NiCr and NiCrAl coating/Nickel alloy 690substrate systems at 1033 K was investigated. Results showed that there was almost no difference in the creep lives between the NiCr and NiCrAl coated specimens at a given stress level, since the contents of Cr used in the NiCr and NiCrAl powders are almost same. The relationship between the minimum creep rate and the applied stress followed the well-known Norton's power law, εmin=Aσn, with the values of A=2.66× 10-16 Mpa-n.h-1 and n=6.48. The relation between the applied stress and time to rupture of the coated specimens can be estimated by using Larson-Miller equation. The θ projection method can be used to accurately characterize the creep behavior of the coated specimens.

  17. Development of the dentistry alloy Ni-Cr-Nb; Desenvolvimento de ligas odontologicas Ni-Cr-Nb

    Energy Technology Data Exchange (ETDEWEB)

    Souza, M.A.; Ramos, A.S.; Hashimoto, T.M., E-mail: mari_sou@hotmail.co [UNESP/FEG, Guaratingueta, SP (Brazil). Fac. de Engenharia. Dept. de Materiais e Tecnologia

    2010-07-01

    This work reports on the structural characterization of Ni-Cr-Mo and Ni-Cr-Nb alloys produced by arc melting. Samples were characterized by means of optical microscopy, X-ray diffraction, scanning electron microscopy, and EDS analysis. Results indicated that the arc melting process was efficient to produce homogeneous structures in Ni-Cr-Mo and Ni-Cr-Nb alloys. The nickel dissolved large amounts of Cr, Mo and Nb, which was detected by EDS analysis and X-ray diffraction. The alloy containing molybdenum indicated the presence of structure based on Ni{sub SS}, while that the alloys containing niobium presented primary grains of Ni{sub SS} and precipitates formed by the simultaneous transformation of the Ni and Ni{sub 3}Nb phases. (author)

  18. Electrodeposition of Ni-Cr alloy on aluminum substrate

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Ni-Cr alloys with mass fraction of 1.4%-23.9 %Cr, 76.1%-98.6 % Ni, and hardness of 70.5-80.5HR were electrodeposited on aluminium substrate from the trivalent chromium sulphate-chloride solution using citric acid as complexing agent. The aluminium was pretreated by means of degreasing and eroding, polishing and twice chemicai immersion of zinc. The effects of electrodeposition parameters such as current density, temperature, pH value and bath concentration on the composition and hardness of deposits were investigated. The results show that the Cr content increases with the increase of current density and the decrease of temperature, and that it increases with the increase of pH value to a maximum and then decreases. The increase of Cr content leads to the increase of hardness of the Ni-Cr layers. The deposits with high Cr content are of good corrosion resistance. Good adherence of Ni-Cr deposits to aluminium substrate is obtained. The Ni-Cr alloys are the Ni-Cr solid solution with fcc crystalline structure. The Ni-Cr alloy deposits are fine, bright and smooth and compact.

  19. Densities of molten Ni-(Cr, Co, W) superalloys

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; YANG Ren-hui; FANG Liang; LIU Lan-xiao; ZHAO Hong-kai

    2008-01-01

    In order to obtain more accurate density for molten Ni-(Cr, Co, W) binary alloy, the densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys were measured with a sessile drop method. It is found that the measured densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys decrease with increasing temperature in the experimental temperature range. The density of alloys increases with increasing W and Co concentrations while it decreases with increasing Cr concentration in the alloy at 1 773-1 873 K. The molar volume of Ni-based alloys increases with increasing W concentration while it decreases with increasing Co concentration. The effect of Cr concentration on the molar volume of the alloy is little in the studied concentration range. The accommodation among atomic species was analyzed. The deviation of molar volume from ideal mixing shows an ideal mixing of Ni-(Cr, Co, W) binary alloys.

  20. Cr-Ni ALLOY ELECTRODEPOSITION AND COMPARISON WITH CONVENTIONAL PURE Cr COATING TECHNIQUE

    Directory of Open Access Journals (Sweden)

    M. Moniruzzaman

    2012-12-01

    Full Text Available Cr coating is widely used as the outer surface of precision parts due to its attractive appearance and superior corrosion resistance properties. It is obtained by electrodeposition via a conventional bath with hexavalent Cr ions. This manufacturing technique has many drawbacks, such as very low efficiency and high operating temperature and it is hazardous to health. In this work, we studied a Cr-Ni alloy deposition technique and compared the alloy coating properties to those with conventional Cr coating. Sequential two-step alloy electrodeposition was also compared. We took varying concentrations of Cr, Ni and complexing agents for the electrodeposition of Cr-Ni alloy and sequential Cr-Ni alloy coating on mild steel. Operating parameters, i.e. current density and temperature, were varied to examine their effects on the coating properties. The coatings thus obtained were characterized by visual observation, corrosion test, microhardness measurement, morphology and chemical analysis. The Cr-Ni alloy coating was found to be more corrosion resistant in 5% NaCl solution and harder than the pure Cr coating obtained by conventional electrodeposition. Toxic gas was produced in a much lower extent in the alloy coating than the conventional Cr coating technique. Again, the two-step Cr-Ni alloy coating was found better in terms of corrosion resistance as well as hardness compared to the Cr-Ni alloy coating. The process was also found to be much more environmentally friendly.

  1. 新型Cr-Ni-Mo和Cr-Ni-Co堆焊合金空蚀性能%Cavitation Erosion Resistance of Novel Cr-Ni-Mo and Cr-Ni-Co Overlaying Alloys

    Institute of Scientific and Technical Information of China (English)

    徐桂芳; 秦敏明; 雷玉成; 陈希章; 李涛

    2012-01-01

    New type Cr-Ni-Mo and Cr-Ni-Co overlaying alloys were prepared by argon tungsten-arc welding (TIG) on 304 stainless steel, and tested by cavitation vibrating device. The cavitation erosion resistance of alloys was compared through the analysis of mass loss. The alloy layer was analyzed by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and microhardness tester. Results indicate that the cavitation erosion resistance of Cr-Ni-Mo and Cr-Ni-Co overlaying alloys is better than that of 304 stainless steel, and the resistance of Cr-Ni-Co is better than Cr-Ni-Mo. In the process of cavitation the damage is preferred to appear in grain boundary. Phase transformation from austenite to martensite happens in the cavitation process of Cr-Ni-Co alloy, and it is helpful to absorb the energy and delay the process of cavitation erosion, and enhance the cavitation erosion resistance effectively. The cavitation erosion resistance of overlaying alloys is related to hardness and work hardening ability.%采用钨极氩弧焊(TIG)将新型Cr-Ni-Mo和Cr-Ni-Co合金堆焊于304不锈钢表面进行空蚀试验,通过失重比较不同合金的抗空蚀性能.采用扫描电镜(SEM)、X射线衍射(XRD)仪和显微硬度计对合金层进行分析.结果表明:Cr-Ni-Mo和Cr-Ni-Co合金的耐空蚀性能均优越于304不锈钢,其中Cr-Ni-Co优于Cr-Ni-Mo;空蚀破坏优先出现在堆焊层的晶界处;Cr-Ni-Co合金在空蚀过程中发生了因奥氏体向马氏体的转变,有利于能量吸收,延缓了空蚀的进行,提高其耐空蚀性能;堆焊合金的抗空蚀能力与合金本身的硬度和加工硬化能力有关.

  2. Chemical speciation of Fe, Mn, Pb, Zn, Cd, Cu, Co, Ni and Cr in the suspended particulate matter off the Mejerda River Delta (Gulf of Tunis, Tunisia)

    Science.gov (United States)

    Helali, Mohamed Amine; Oueslati, Walid; Zaaboub, Noureddine; Added, Ayed; Aleya, Lotfi

    2016-06-01

    Fluxes of suspended particulate matter (SPM) and their associated metals were performed off the Mejerda River Delta during both the wet (March) and the dry (July) seasons in 2012, using sediment traps at study stations at depths of 10, 20 and 40 m. Fluxes nearest to the Mejerda outlet were more significant, especially during winter (36 g m-2 day-1), but dissipated further offshore, 24.5-6 g m-2 day-1 at the 20 m and 21.8-4.8 g m-2 day-1 at the 40 m stations. Many variations observed in seasonal and spatial metal fluxes are similar to those of SPM, in particular Pb and Zn, probably because they are associated with the mining activity characteristic of the Mejerda catchment. Chemical speciation reveals that most of the metals (20-100%) are bound to the residual fraction. The most toxic metals (Pb, Zn) are bound in part to the exchangeable fraction (20-50% for Pb and 5-15% for Zn) making them relatively bioavailable and therefore potentially toxic. While Cu and Cd fluxes are not always clearly established according to season, both metals are apparently sequestered deep in the sediment, bound especially to clays (40-80% for Cd and up to 100% for Cu).

  3. Microstructure and mechanical properties of thermal sprayed nanostructured Cr3C2-Ni20Cr coatings

    Directory of Open Access Journals (Sweden)

    Cecilio Alvares da Cunha

    2008-06-01

    Full Text Available Cr3C2-Ni20Cr coatings have been used for corrosion and wear resistant applications. However, one of the shortcomings of these coatings is its low hardness, and consequent low wear resistance, for long term high temperature applications. Nanostructured coatings of many materials have exhibited higher hardness and strength compared with conventional coatings of the same material. Consequently, nanostructured coatings of other materials, including Cr3C2-Ni20Cr have been attempted to enhance overall performance. In this study the effects of high energy milling parameters on Cr3C2-25(Ni20Cr powder characteristics as well as the microstructure and mechanical properties of nanostructured Cr3C2-25(Ni20Cr coatings formed by high velocity oxygen fuel (HVOF spraying have been evaluated. The average particle size and crystallite size of milled Cr3C2-25(Ni20Cr powders decreased with increase in milling time and this decrease was more pronounced in nitrogen compared to that in hexane. This difference has been attributed to a cushioning effect in the latter medium. The coatings prepared with milled Cr3C2-25(Ni20Cr powders had a more uniform microstructure, were harder and had higher relative fracture toughness compared with coatings prepared with as-received powders.

  4. Oxidation Behaviour of Sputtered Ni-3Cr-20Al Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The oxidation behavior of sputtered Ni-3Cr-20Al coating at 900°C in air was investigated. A dense Al2O3 layer was formed on the sputtered Ni-3Cr-20Al coating after 200 h oxidation.However, owing to the segregation of Ni3Al during oxidation Focess at high temperature, the spinel NiAl2O4 was also formed in the Al2O3 layer. It was found that the formation of NiAl2O4had no detrimental effect on the oxidation resistance of the sputtered Ni-3Cr-20Al coating due to the excellent adhesion shown by the Al2O3 and NiAl2O4 complex oxide scale.

  5. Diurnal concentrations variations, size distributions for ambient air particles and metallic pollutants (Cr, Mn, Ni, Cd, Pb) during summer season at a traffic area.

    Science.gov (United States)

    Fang, Guor-Cheng; Kuo, Yu-Chen; Zhuang, Yuan-Jie; Chen, Yu-Cheng

    2014-07-01

    This study characterized and discussed particulate ambient air particulate concentrations and seasonal variations for PM18, PM10, PM2.5, and PM1 during June 2013-July 2013 at this traffic sampling site. In addition, this study also characterized the ambient air particulates size distributions by using MOUDI-100S4 sampler to collect 1-day the ambient suspended particles (PM18, PM10, PM2.5, and PM1) at this sampling site. In addition, the study also showed that the main pollutants contributions were from traffic and residual areas. As for the pollutants seasonal concentrations variations, the results indicated that the average particle concentrations orders were all displayed as daytime > nighttime for PM18, PM10, PM2.5 and PM1 at this characteristic sampling site. The results further indicated that the mean highest of metal concentrations in this study indicated that the average metal concentration were all displayed as Mn > Cr > Ni > Pb > Cd for PM18, PM10, PM2.5 and PM1 on daytime and nighttime at this characteristic sampling site. PMID:24619364

  6. Electroplating process of amorphous Fe-Ni-Cr alloy

    Institute of Scientific and Technical Information of China (English)

    何湘柱; 夏畅斌; 王红军; 龚竹清; 蒋汉瀛

    2001-01-01

    A novel process of electroplating amorphous Fe-Cr-Ni alloy in chloride aqueous solution with Fe( Ⅱ ), Ni ( lⅡ ) and Cr( Ⅲ ) was reported. Couple plasma atomic emission spectrometry (ICP-AES), X-ray diffractometry(XRD),scanning electronic microscopy(SEM), microhardness test and rapid heating-cooling method were adopted to detect the properties of the amorphous Fe-Ni-Cr deposit, such as composition, crystalline structure, micrograph, hardness, and adherence between deposit and substrate. The effects of the operating parameters on the electrodeposit of the amorphous FeNi-Cr alloy were discussed in detail. The results show that a 8.7 μm thick mirror-like amorphous Fe-Ni-Cr alloy deposit,with Vicker's hardness of 530 and composition of 45%~55% Fe, 33%~37% Ni, 9%~23% Cr was obtained by electroplating for 20 min at room temperature( 10 30 C ), cathode current 10~16 A/dm2, pH = 1.0~3.0. The XRD pat terns show that there only appears a broad hump around 2θ of 41 °~47 °for the amorphous Fe-Ni-Cr alloy deposit, while the SEM micrographs show that the deposit contains only a few fine cracks but no pinholes.

  7. Density of Ni-Cr Alloy in the Mushy State

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The density of Ni-Cr alloy in the mushy state has been measured using the modified sessile drop method. The density of Ni-Cr alloy in the mushy state was found to decrease with increasing temperature and Cr concentration in alloy.The molar volume of Ni-Cr alloy in the mushy state therefore increases with increasing the Cr concentration in alloy.The ratio of the difference of density divided by the temperature difference between liquidus and solidus temperatures decreases with increasing Cr concentration. The density of the alloy increased with the precipitation of a solid phase in alloy during the solidification process. The temperature dependence of the density of alloy in the mushy state was not linear but biquadratic.

  8. Isothermal diffusion in the Fe-Cr-Ni system

    International Nuclear Information System (INIS)

    Mutual diffusion in the Fe-Cr-Ni ternary system has been studied. The concentration dependence of the matrix of the external diffusion coefficients at 1300 deg C in the γ-area of the Fe-Cr-Ni system has been experimentally determined. It is shown that quasi-binary description of diffusion is possible for the alloys rich in iron and impossible for the alloys poor in iron. Certain limiting relations occurring when passing from ternary diffusion to binary diffusion have been experimentally confirmed. None of the coefficients of mutual diffusion in the Fe-Cr-Ni system has been found to correlate with the trend of the solidus

  9. Composite Ni/NiO-Cr2O3 Catalyst for Alkaline Hydrogen Evolution Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Bates, MK; Jia, QY; Ramaswamy, N; Allen, RJ; Mukerjee, S

    2015-03-12

    We report a Ni-Cr/C electrocatalyst with unpreeedented massactivity for the hydrogen evolution reaction (HER). in alkaline electrolyte. The HER Oietics of numerous binary and ternary Ni-alloys and composite Ni/metal-euride/C samples were evaluated in aquebus 0.1 M KOH electrolyte. The highest HER mass-activity was observed for Ni-Cr materials which exhibit metallic Ni as well as NiOx and Cr2O3 phases as determined by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) analysis. The onset of the HER is significantly improved compared to munerous binary dor ternary Ni-alloys, inCluding Ni Mg materials. It is likely that at adjacent Ni/NiOx sites, the oxide acts as a sink for OHads, while the metallic Ni acts as a, sink for the H-ads, intermediate of the HER, thus minimizing the high activation energy of hydrogen evolution via water reduction. This is confirmed by in situ XAS studies that show that the synergistic HER enhancement is due to NiO content and that the Cr2O3 appears to stabilize the composite NiO component-under HER conditions (where NiOx would typically be reduced to metallic Ni-0). Furthermore, in contrast to Pt, the Ni(O-x)/Cr2O3 catalyst appears resistant to poisoning by the anion.exchange ionomer (AEI), a serloua consideration when applied to an anionic polymer electrolyte interface. Furthermore, we report a: detailed model of the double layer interface which helps explain the observed ensemble effect in the presence of AEI.

  10. CD21/CR2的研究进展

    Institute of Scientific and Technical Information of China (English)

    王琳

    2003-01-01

    补体Ⅱ型受体CD21/CR2是B淋巴细胞膜表面C3d/iC3b受体,在免疫应答中起重要的作用。同时人CD21/CR2也是EB病毒膜表面糖蛋白gp350/gp220、HIV-1等的受体,CD21/CR2以不同的结构域与这些配体结合,表现出多种生物学特性。弄清CD21/CR2的结构和功能,可以指导基础免疫研究,也可明确临床许多疾病的发病机理和治疗方向。

  11. Electrochemical behavior of Co-Cr and Ni-Cr dental cast alloys

    Institute of Scientific and Technical Information of China (English)

    Viswanathan S. SAJI; Han-Cheol CHOE

    2009-01-01

    The cast structures influencing the electrochemical corrosion behavior of Co-Cr and Ni-Cr dental alloys were studied using potentiodynamic polarization and AC impedance in 0.9% (mass fraction) NaCl solution at (37±1) ℃. The phase and microstructure of the alloys that were fabricated using two different casting methods viz. centrifugal casting and high frequency induction casting, were examined using X-ray diffraction analysis, scanning electron microscopy and energy dispersive spectroscopy. The roles of alloying elements and the passive film homogeneity on the corrosion resistance of Co-Cr-Mo and Ni-Cr-Mo dental cast alloys were reviewed. The results of electrochemical study show that the dependence of corrosion resistance on the microstructure associated with the casting methods is marginal. The Co-Cr alloy exhibits more desirable corrosion resistance properties than the Ni-Cr alloy. There is severe preferential dissolution of Ni-rich, Cr and Mo depleted zones in the Ni-Cr alloy.

  12. Mechanical and Tribological Properties of HVOF-Sprayed (Cr3C2-NiCr+Ni) Composite Coating on Ductile Cast Iron

    Science.gov (United States)

    Ksiazek, Marzanna; Boron, Lukasz; Radecka, Marta; Richert, Maria; Tchorz, Adam

    2016-07-01

    The aim of the investigations was to compare the microstructure, mechanical, and wear properties of Cr3C2-NiCr+Ni and Cr3C2-NiCr coatings deposited by HVOF technique (the high-velocity oxygen fuel spray process) on ductile cast iron. The effect of nickel particles added to the chromium carbide coating on mechanical and wear behavior in the system of Cr 3 C 2 -NiCr+Ni/ductile cast iron was analyzed in order to improve the lifetime of coated materials. The structure with particular emphasis of characteristic of the interface in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron was studied using the optical, scanning, and transmission electron microscopes, as well as the analysis of chemical and phase composition in microareas. Experimental results show that HVOF-sprayed Cr3C2-NiCr+Ni composite coating exhibits low porosity, high hardness, dense structure with large, partially molten Ni particles and very fine Cr3C2 and Cr7C3 particles embedded in NiCr alloy matrix, coming to the size of nanocrystalline. The results were discussed in reference to examination of bending strength considering cracking and delamination in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron as well as hardness and wear resistance of the coating. The composite structure of the coating provides the relatively good plasticity of the coating, which in turn has a positive effect on the adhesion of coating to the substrate and cohesion of the composite coating (Cr3C2-NiCr+Ni) in wear conditions.

  13. High-temperature nitridation of Ni-Cr alloys

    Science.gov (United States)

    Kodentsov, A. A.; Gülpen, J. H.; Cserháti, C.; Kivilahti, J. K.; van Loo, F. J. J.

    1996-01-01

    The nitriding behavior of nickel-chromium alloys was investigated at 1398 K over the range 1 to 6000 bar of external nitrogen pressure. The morphology of the nitrided zone depends on the concentration of chromium in the initial alloy and the N2 pressure (fugacity) applied upon the system. The transition from CrN to Cr2N precipitation was observed within the reaction zone after nitriding at 100 to 6000 bar of N2 when the chromium content in the initial alloys was 28.0 at. pct or higher. It is shown that the ternary phase π (Cr10Ni7N3) is formed in this system at 1273 K. through a peritectoid reaction between Cr2N and nickel solid solution and becomes unstable above 1373 K. The thermodynamic evaluation of the Ni-Cr-N system was performed and phase equilibria calculated. Evidence for “up hill” diffusion of nitrogen near the reaction front during the internal nitridation of Ni-Cr alloys at 1398 K was found. It was attributed to the relative instability of chromium nitrides and strong Cr-N interaction in the matrix of the Ni-based solid solution within the nitrided zone.

  14. Enthalpy of Mixing of Liquid Al-Cr and Cr-Ni Alloys

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The partial and the integral enthalpies of mixing of liquid Al-Cr and Ni-Cr binary alloys have been determined by high temperature isoperibolic calorimetry at 1723±5 K and 1729±5 K, respectively. The results were analytically described by the thermodynamically adapted power series (TAPS). The enthalpies of mixing values for both binary liquid melts are small and negative and in good agreement with the available literature data. Minima of the mixing enthalpies of liquid Al-Cr and Ni-Cr alloys are -7.0 kJ.mol-1 at 46 at. pct Cr and -3.0 k J@mol-1 at 37 at. pct Cr,respectively.

  15. The Hot Corrosion Performance of NiCr-Cr3 C2 Cermet Coating to Boiler Tube

    Institute of Scientific and Technical Information of China (English)

    DINGZhang-xiong; TUGuo-fu

    2004-01-01

    Three kinds of NiCr-Cr3 C2 cermet coatings were designed and deposited by the subsonic velocity flame spraying, and their performances of hot corrosion performance were evaluated in comt)arison with 102G,20G boiler tube steel, FeCrAl, NiCrTi, Ni5OCr and NiCrAIMoFe-Cr3 C2 coatings, which are widely used at present for protection of boiler tubes. Meanwhile, the influence of sealer on the hot corrosion resistance of warious coatings and the mechanisms of coating corrosion were explored.

  16. Cr-Ni ALLOY ELECTRODEPOSITION AND COMPARISON WITH CONVENTIONAL PURE Cr COATING TECHNIQUE

    OpenAIRE

    Moniruzzaman, M.; M.M. Rakib; F.T. Matin

    2012-01-01

    Cr coating is widely used as the outer surface of precision parts due to its attractive appearance and superior corrosion resistance properties. It is obtained by electrodeposition via a conventional bath with hexavalent Cr ions. This manufacturing technique has many drawbacks, such as very low efficiency and high operating temperature and it is hazardous to health. In this work, we studied a Cr-Ni alloy deposition technique and compared the alloy coating properties to those with conventional...

  17. ICP-AES标准加入法测定电镀排放废水中Cd、Cr、Ni%Determination of the contents of Cd,Cr,Ni in electroplating discharged wastewater by the method of standard addition of ICP-AES

    Institute of Scientific and Technical Information of China (English)

    潘慧; 冯光勇; 康元

    2014-01-01

    电镀排放废水基体复杂多变,采用电感耦合等离子体发射光谱(ICP-AES)标准加入法测定电镀排放废水中的Cd、Cr、Ni,可解决基体匹配的难题。对仪器分析条件的选择、酸度和盐度的影响、共存元素的干扰进行了研究,该方法回收率为95%~106%,RSD为3.7%~6.3%。%Wastewater matrix from electroplating wastewater is complex and multivariable. The method of standard addition of inductively coupled plasma atomic emission spectrometry (ICP-AES) has been used for the determination of the contents of Cd,Cr,and Ni in electroplating wastewater,in order to solve the problem of matrix matching. The selection of instrument analysis conditions ,the influence of acidity and salinity ,and the interference of coexisting elements are studied. The recovery rate of the method is 95%-106%,and RSD 3.7%-6.3%.

  18. Order-disorder transitions in NiCr2S4

    DEFF Research Database (Denmark)

    Vaqueiro, P.; Powell, A.V.; Lebech, B.

    2000-01-01

    Order–disorder transitions in NiCr2S4 have been investigated by high-temperature powder neutron diffraction. At 835(5)°C, NiCr2S4 transforms from the monoclinic Cr3S4 structure to a hexagonal cation-deficient NiAs structure.......Order–disorder transitions in NiCr2S4 have been investigated by high-temperature powder neutron diffraction. At 835(5)°C, NiCr2S4 transforms from the monoclinic Cr3S4 structure to a hexagonal cation-deficient NiAs structure....

  19. Microstructure and crack resistance of low carbon Cr-Ni and Cr-Ni-W steel after austempering

    Science.gov (United States)

    Avdjieva, Tatyana; Tsutsumanova, Gichka; Russev, Stoyan; Staevski, Konstantin

    2013-09-01

    The microstructure of the low carbon Cr-Ni steel after slow cooling from austenization temperature represents a mix of granulated bainite with islands from carbon-rich martensite and carbon-poor austenite. After quick cooling throwing in salt bath from austenization temperature the microstructure is lath bainite. However, in the same treatment conditions, the microstructure of the low carbon Cr-Ni-W steel is different — clusters consist from lath ferrite and retained austenite, disposed in the frame of parent's austenite grains. The cooling velocity has no effect upon the structure making. The impact toughness of the steel with tungsten content is bigger than the steel without tungsten.

  20. Grain boundary self-diffusion of 51Cr in Fe-Cr-Ni alloys

    International Nuclear Information System (INIS)

    The grain boundary self-diffusion characteristics P=α.δ.Dg (α is the segregation factor, δ is the grain boundary width and Dg is the grain boundary diffusion coefficient) of 51Cr were measured in the two alloys Fe-18 Cr-12 Ni and Fe-21 Cr-31 Ni. Experiments were performed in the temperature range from 973 to 1223 K using the sectioning method. In the frames of experimental errors there was found no significant difference between the results for both alloys. The temperature dependence of the triple product P for both materials can be thus described by the Arrhenius-type equation P(Cr)=(1.17+2.1-0.75).10-10.exp {-(234±19)/RT} m3/s. Within the errors, P values obtained in this paper are identical with those obtained in previous work for diffusion of 59Fe and 63Ni in the same materials. For the diffusion of all three basic constituents in both alloys the following equation is proposed P (Fe, Ni, Cr)=(6.7+9.9-4.0).10-12.exp {-(207±17)/RT} m3/s. (orig.)

  1. PREPARATION AND PROPERTIES OF Ni-Cr AND Fe-Cr-Al FILMS BY VACUUM EVAPORATION

    Institute of Scientific and Technical Information of China (English)

    X. W. Shi; Z.Y. Liu; D.C. Zeng; C.M. Li

    2003-01-01

    Ni-Cr and Fe-Cr-Al films deposited on the Al2O3 substrate are studied by a method of vacuum evaporation in this paper. Influence of resistance value on density and evaporation parameters of the films reveals that the resistance of films and the adhesion of films to substrates are determined by the evaporation time and the substrate temperate under the condition of the maximum vacuity of 6.2×10-4 pa, respectively.

  2. Investigation of Ni and Cd electrokinetic removal from a sediment

    OpenAIRE

    Rajić Ljiljana; Dalmacija Božo; Ugarčina-Perović Svetlana

    2012-01-01

    In this paper we examine the efficacy of the enhanced electrokinetic remediation of a sediment from the Tamiš River contaminated with Ni and Cd. The moving anode technique and an increased cathodic compartment length were simultaneously used to enhance the technique. The removal efficacy increase appeared after the enhanced treatment for Ni (23%) and Cd (73%). The increased cathodic compartment length successfully prevented OH- ions migration in the sediment. Finally, sediment classific...

  3. Blending Cr2O3 into a NiO-Ni electrocatalyst for sustained water splitting.

    Science.gov (United States)

    Gong, Ming; Zhou, Wu; Kenney, Michael James; Kapusta, Rich; Cowley, Sam; Wu, Yingpeng; Lu, Bingan; Lin, Meng-Chang; Wang, Di-Yan; Yang, Jiang; Hwang, Bing-Joe; Dai, Hongjie

    2015-10-01

    The rising H2 economy demands active and durable electrocatalysts based on low-cost, earth-abundant materials for water electrolysis/photolysis. Here we report nanoscale Ni metal cores over-coated by a Cr2 O3 -blended NiO layer synthesized on metallic foam substrates. The Ni@NiO/Cr2 O3 triphase material exhibits superior activity and stability similar to Pt for the hydrogen-evolution reaction in basic solutions. The chemically stable Cr2 O3 is crucial for preventing oxidation of the Ni core, maintaining abundant NiO/Ni interfaces as catalytically active sites in the heterostructure and thus imparting high stability to the hydrogen-evolution catalyst. The highly active and stable electrocatalyst enables an alkaline electrolyzer operating at 20 mA cm(-2) at a voltage lower than 1.5 V, lasting longer than 3 weeks without decay. The non-precious metal catalysts afford a high efficiency of about 15 % for light-driven water splitting using GaAs solar cells. PMID:26307213

  4. Thermomechanical behavior of rapidly solidified Fe-25Cr-20Ni

    Energy Technology Data Exchange (ETDEWEB)

    Draissia, M.; Boukhris, N.; Debili, M.Y. [LM2S, Dept. de Physique, Faculte des Sciences, Univ. Badji-Mokhtar, Annaba, Algerie (Turkey)

    2004-07-01

    The thermomechanical treatment at 1050 C under a stress of about 30 MPa, of milled ribbons from Fe-25Cr-20Ni (0.060%Ni-0.1%Ti) refractory stainless steel, leads to a recrystallisation of the as-melt-spun structure which is intermediate between cellular and columnar dendritic. The mean grain size in the relatively high density zones (85%) may be considered as low and do not exceed 10{mu}m. Other grains appear abnormally large and reach 30 {mu}m. The origin of these grains, must be researched in an exaggerate growth phenomenon under a local deformation near the critical work hardening. (orig.)

  5. Hochtemperatur-Thermochemie im System Al-Cr-Ni-O

    OpenAIRE

    Saltikov, Pavlo

    2003-01-01

    Das System Al-Cr-Ni ist von großer Bedeutung in der Energieerzeugungs- und der Luftfahrttechnik als Basis für die Superlegierungen. Zur Steigerung des Wirkungsgrads einer Gasturbine müssen die neuen Herstellungstechniken (z.B. gerichtete Erstarrung) bzw. Konstruktionskonzepte (keramische Wärmedämmschichten) eingeführt werden, die den Betrieb bei höheren Verbrennungstemperaturen ermöglichen. Obwohl die Ni-Basis-Superlegierungen in den letzten Jahren sehr ausgiebig untersucht worden waren, blei...

  6. Role of oxygen diffusion at Ni/Cr2O3 interface in intergranular oxidation of Ni-Cr alloy

    Science.gov (United States)

    Medasani, Bharat; Sushko, Maria; Schreiber, Daniel; Rosso, Kevin; Bruemmer, Stephen

    Certain Ni-Cr alloys used in nuclear systems experience intergranular oxidation and stress corrosion cracking when exposed to high-temperature water leading to their degradation and unexpected failure. To develop a mechanistic understanding of grain boundary oxidation processes, we proposed a mesoscale metal alloy oxidation model that combines quantum Density Functional Theory (DFT) with mesoscopic Poisson-Nernst-Planck/classical DFT. This framework encompasses the chemical specificity of elementary diffusion processes and mesoscale reactive dynamics, and allows modeling oxidation processes on experimentally relevant length scales from first principles. As a proof of concept, a preliminary model was previously employed that limited oxygen diffusion pathways to those through the oxide phase and did not allow oxygen diffusion in the alloy or across oxide/alloy interfaces. In this work, we expand the model to include oxygen diffusion pathways along Ni/Cr2O3 interfaces and demonstrate the increasing importance of such pathways for intergranular oxidation of Ni-Cr alloys with high Cr content. This work is supported by the U.S. Dept. of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. Simulations are performed using PNNL Institutional Computing facility.

  7. Moessbauer Investigation of Electrodeposited Sn-Zn, Sn-Cr, Sn-Cr-Zn and Fe-Ni-Cr Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmann, E.; Stichleutner, S. [Eoetvoes University, Department of Nuclear Chemistry and Research Group of Nuclear Methods in Structural Chemistry HAS (Hungary); El-Sharif, M.; Chisholm, C. U. [Glasgow Caledonian University (United Kingdom); Sziraki, L.; Homonnay, Z.; Vertes, A. [Eoetvoes University, Department of Nuclear Chemistry and Research Group of Nuclear Methods in Structural Chemistry HAS (Hungary)

    2002-06-15

    {sup 57}Fe and {sup 119}Sn CEMS, XRD and electrochemical measurements were used to investigate the effect of the preparation parameters and the components on the structure and phase composition of electrodeposited Fe-Ni-Cr alloys in connection with their corrosion behavior. XRD of the electrodeposits reflect an amorphous-like character. {sup 57}Fe CEM spectra of Fe-Ni-Cr electrodeposited samples, prepared in a continuous flow plating plastic circulation cell with variation of current density, electrolyte velocity and temperature, can be evaluated as a doublet associated with a highly disordered paramagnetic solid solution phase. This phase was identified earlier in Fe-Ni-Cr electrodeposits that were prepared by another plating method and contained both ferromagnetic and paramagnetic metastable phases. This is the first time that we have succeeded to prepare Fe-Ni-Cr alloys containing only the metastable paramagnetic phase. The effect of the plating parameters on the structure is also analysed by the quadrupole splitting distribution method. {sup 119}Sn CEM spectra of all Sn-containing plated alloys show a broad line envelop which can be decomposed at least into two components. One can be associated with {beta}-tin. The other one can be assigned to an alloy phase. The structure and distribution of microenvironments of these phases depends on the plating parameters especially on the parameters of the reverse pulse applied.

  8. Combustion Synthesis of Large Bulk Nanostructured Ni65Al21Cr14 Alloy

    Directory of Open Access Journals (Sweden)

    Jiqiang Ma

    2011-01-01

    Full Text Available A large bulk nanostructured Ni65Al21Cr14 alloy with dimensions of Φ 100 mm × 6 mm was produced by combustion synthesis technique followed with rapid solidification. The Ni65Al21Cr14 alloy was composed of γ′-Ni3Al/γ-Ni(Al, Cr eutectic matrix and γ-Ni(Al, Cr dendrite. The eutectic matrix consisted of 80–150 nm cuboidal γ′-Ni3Al and 2–5 nm γ-Ni(Al, Cr boundary. The dentrite was comprised of high-density growth twins with about 3–20 nm in width. The nanostructured Ni65Al21Cr14 alloy exhibited simultaneously high fracture strength of 2200 MPa and good ductility of 26% in compression test.

  9. Nonradiative recombination processes in (CdTe, CdCrTe)/CdMgTe quantum well structures

    International Nuclear Information System (INIS)

    Photoluminescence transitions in (CdTe,CdCrTe)/CdMgTe structure grown by molecular beam epitaxy are studied. Photoluminescence investigations show a very strong reduction of the photoluminescence intensity from chromium doped quantum wells. We explain this fact by a very efficient nonradiative recombination in the chromium-doped quantum wells. The present results indicate that the Auger-type energy transfer from excitons to chromium ions is responsible for the photoluminescence deactivation. The efficiency of this process is evaluated. (author)

  10. Corrosion behavior of CuCrNiAl alloy in HCl solutions

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The corrosion behavior of a CuCrNiAl alloy in HCl solutions was studied by means of metallograph, XRD, SEM/EDX and TEM methods. The results show that in low concentration of HCl solutions, Cu of CuCrNiAl alloy is more easily subject to corrsion than Cr; the dechromisation of the CuCrNiAl alloy occurs at a certain concentration of HCl solutions, at the same time Al of CuCrNiAl alloy is subject to corrosion also. The dechromisation corrosion occurs initially at the interface between Cr phase and Cu phase, then it gradually extends Cr phase until Cr phase is dissolved completely. It is also revealed that the tendency of dechromisaion of the CuCrNiAl alloy increases with the increase in concentration and temperature of HCl solutions.

  11. Effects of Ni vacancy, Ni antisite, Cr and Pt on the third-order elastic constants and mechanical properties of NiAl

    KAUST Repository

    Wu, Shaohua

    2014-12-01

    Effects of Ni vacancy, Ni antisite in Al sublattice, Cr in Al sublattice, Pt in Ni sublattice on the second-order elastic constants (SOECs) and third-order elastic constants (TOECs) of the B2 NiAl have been investigated using the first-principles methods. Lattice constant and the SOECs of NiAl are in good agreement with the previous results. The brittle/ductile transition map based on Pugh ratio G/B and Cauchy pressure Pc shows that Ni antisite, Cr, Pt and pressure can improve the ductility of NiAl, respectively. Ni vacancy and lower pressure can enhance the Vickers hardness Hv of NiAl. The density of states (DOS) and the charge density difference are also used to analysis the effects of vacancy, Ni antisite, Cr and Pt on the mechanical properties of NiAl, and the results are in consistent with the transition map. © 2014 Elsevier Ltd. All rights reserved.

  12. Using hyperaccumulator plants to phytoextract soil Ni and Cd

    Energy Technology Data Exchange (ETDEWEB)

    Chaney, R.L. [USDA-Agricultural Research Service, Animal Manure and By-Products Lab, Beltsville, MD (United States); Scott Angle, J.; McIntosh, M.S. [Univ. of Maryland, College Park, MD (United States); Phytoextraction Associates LLC, Baltimore, MD (United States); Reeves, R.D. [Inst. of Fundamental Science-Chemistry, Massey Univ., Palmerston North, NZ (United States); Li Yin-Ming; Brewer, E.P. [Viridian LLC, Houston, TX (United States); Chen Kuang-Yu; Synkowski, E.C.; Leigh Broadhurst, C.; Wang, S. [Univ. of Maryland, College Park, MD (United States); Roseberg, R.J. [Oregon State Univ., Central Point, OR (United States); Perner, H. [Inst. for Plant Nutrition, Hohenheim Univ. (Germany); Baker, A.J.M. [Univ. of Melbourne, Melbourne (Australia)

    2005-04-01

    Two strategies of phytoextraction have been shown to have promise for practical soil remediation: domestication of natural hyperaccumulators and bioengineering plants with the genes that allow natural hyperaccumulators to achieve useful phytoextraction. Because different elements have different value, some can be phytomined for profit and others can be phytoremediated at lower cost than soil removal and replacement. Ni phytoextraction from contaminated or mineralized soils offers economic return greater than producing most crops, especially when considering the low fertility or phytotoxicity of Ni rich soils. Only soils that require remediation based on risk assessment will comprise the market for phytoremediation. Improved risk assessment has indicated that most Zn + Cd contaminated soils will not require Cd phytoextraction because the Zn limits practical risk from soil Cd. But rice and tobacco, and foods grown on soils with Cd contamination without corresponding 100-fold greater Zn contamination, allow Cd to readily enter food plants and diets. Clear evidence of human renal tubular dysfunction from soil Cd has only been obtained for subsistence rice farm families in Asia. Because of historic metal mining and smelting, Zn + Cd contaminated rice soils have been found in Japan, China, Korea, Vietnam and Thailand. Phytoextraction using southern France populations of Thlaspi caerulescens appears to be the only practical method to alleviate Cd risk without soil removal and replacement. The southern France plants accumulate 10-20-fold higher Cd in shoots than most T. caerulescens populations such as those from Belgium and the UK. Addition of fertilizers to maximize yield does not reduce Cd concentration in shoots; and soil management promotes annual Cd removal. The value of Cd in the plants is low, so the remediation service must pay the costs of Cd phytoextraction plus profits to the parties who conduct phytoextraction. Some other plants have been studied for Cd

  13. Wear behaviour of HVOF thermal sprayed WC-Co and CrC-NiCr coatings

    Energy Technology Data Exchange (ETDEWEB)

    Forn, A.; Picas, J.A. [Dept. de Ciencia de Materials i Enginyeria Metallurgica, Univ. Politecnica de Catalunya, Vilanova i la Geltru (Spain); Matthaeus, G. [Thermico GmbH and Co. KG., Castrop-Rauxel (Germany)

    2003-07-01

    One of the most important uses of HVOF thermal sprayed coatings is for wear resistance. The present study describes and compare the mechanical and tribological properties of the thermal sprayed CrC75 (NiCr20) 25, CrC60 (NiCr20) 40, WC Co 88 12 and WC Co Cr 86 10 4 coatings, obtained by HVOF technology (High Velocity Oxy-Fuel). These coatings are required to provide protection against sliding, abrasive, erosive and fretting wear and they are candidates for replacement of hazardous hard chromium plating coatings used today in the industry on several applications. The coating microstructures were characterised by SEM microscopy. Differences in roughness have been determined by profilometry. The ultra-microindentation technique was applied to measure the hardness and the elasto-plastic properties of the coating. Experiments using a tribometer (pin on disc configuration) under lubricated and dry conditions have been performed in order to evaluate the friction and wear properties of the different coatings. It was found that the coatings with a higher carbide particle percentage presented poorer abrasive wear resistance than coatings with higher metallic binder phase, under all the conditions examined. This fact could be explained in terms of differences of cohesion between the carbide particles and the binder phase. (orig.)

  14. Wear behaviour of HVOF thermal sprayed WC-Co and CrC-NiCr coatings

    International Nuclear Information System (INIS)

    One of the most important uses of HVOF thermal sprayed coatings is for wear resistance. The present study describes and compare the mechanical and tribological properties of the thermal sprayed CrC75 (NiCr20) 25, CrC60 (NiCr20) 40, WC Co 88 12 and WC Co Cr 86 10 4 coatings, obtained by HVOF technology (High Velocity Oxy-Fuel). These coatings are required to provide protection against sliding, abrasive, erosive and fretting wear and they are candidates for replacement of hazardous hard chromium plating coatings used today in the industry on several applications. The coating microstructures were characterised by SEM microscopy. Differences in roughness have been determined by profilometry. The ultra-microindentation technique was applied to measure the hardness and the elasto-plastic properties of the coating. Experiments using a tribometer (pin on disc configuration) under lubricated and dry conditions have been performed in order to evaluate the friction and wear properties of the different coatings. It was found that the coatings with a higher carbide particle percentage presented poorer abrasive wear resistance than coatings with higher metallic binder phase, under all the conditions examined. This fact could be explained in terms of differences of cohesion between the carbide particles and the binder phase. (orig.)

  15. Evaluation of hot corrosion protection of Cr-Al and CoNiCrAlY on IN-738LC

    Energy Technology Data Exchange (ETDEWEB)

    Khajavi, M.R. [Niroo Research Institute - Chemistry and Materials Research Center - Metallurgy Dept. End of Pounak-e-Bakhtari, P.O.Box 14665-517, Post Code 1468617151, Blvd., Shahrak-e-Gharb, Tehran (Iran)]|[Shiraz University - Materials Science and Engineering Department, Engineering School, Shiraz University, Shiraz (Iran); Pasha, A. [Niroo Research Institute - Chemistry and Materials Research Center - Metallurgy Dept. End of Pounak-e-Bakhtari, P.O.Box 14665-517, Post Code 1468617151, Blvd., Shahrak-e-Gharb, Tehran (Iran); Shariat, M.H. [Shiraz University - Materials Science and Engineering Department, Engineering School, Shiraz University, Shiraz (Iran)

    2004-07-01

    A program was conducted to evaluate the relative corrosion resistance of CoNiCrAlY and Chromium modified Aluminide on IN738-LC, used for turbine blades. The corrosion experiments were performed in a laboratory tube furnace. The microstructure of coatings was characterized by using optical and scanning electron microscopy techniques. The results indicated that at a temperature of 800 deg. C the CoNiCrAlY is more protective than Cr-Al coating. (authors)

  16. Grain boundary segregation in FeCrNi model alloys; Korngrenzensegregation in FeCrNi-Modellegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Schlueter, B.; Schneider, F.; Mummert, K. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany); Muraleedharan, P. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Div. of Metallurgy

    1998-12-31

    P and S segregate at the grain boundaries and thus increase susceptibility to intergranular corrosion at those sites. This could be proven by means of nitric acid-chromate tests and potentiostatic etching tests. There is a direct connection between loss in mass, mean depth of intergranular corrosion attacks, dissolution current density, and level of segregation-induced concentration of P and S at the grain boundaries. The segregation effect at these sites was found to be most evident in specimens of the examined Fe-Cr-Ni steel which had been heat-treated for 1000 hours at 550 C. However, segregation occurs also in materials that received a heat treatment of 400 C/5000 hours, while intergranular corrosion is observed only after heat treatment of 500 C/1000 hours. Apart from segregation of P, formation of Cr-rich phosphides is observed, which leads to depletion of Cr at the precipitates. (orig./CB) [Deutsch] P und S segregieren an die KG und erhoehen dort die IK-Anfaelligkeit. Dies konnte mit Hilfe von Salpetersaeure-Chromat- und Potentiostatischem Aetztest nachgewiesen werden. Es besteht ein direkter Zusammenhang zwischen Masseverlust, mittlerer IK-Angriffstiefe, Aufloesungsstromdichte und Hoehe der segregationsbedingten Anreicherungen von P und S an den KG. Der KG-Segregationseffekt am untersuchten Fe-Cr-Ni-Stahl ist im Waermebehandlungszustand 550 C/1000 h am deutlichsten ausgepraegt. Aber auch bereits bei 400 C/5000 h findet Segregation statt. IKSpRK tritt nur im Waermebehandlungszustand 550 C/1000 h auf. Neben der P-Segregation wird die Bildung Cr-reicher Phosphide beobachtet, die zur Abreicherung von Cr an den Ausscheidungen fuehrt. (orig.)

  17. Studies on the Sliding Wear Performance of Plasma Spray Ni-20Cr and Ni3Al Coatings

    Science.gov (United States)

    Kaur, Maninder; Singh, Harpreet; Singh, Balraj; Singh, Bhupinder

    2010-01-01

    Two metallic powders namely Ni-20Cr and Ni3Al were coated on AISI 309 SS steel by shrouded plasma spray process. The wear behavior of the bare, Ni-20Cr and Ni3Al-coated AISI 309 SS steel was investigated according to ASTM Standard G99-03 on a Pin-on-Disc Wear Test Rig. The wear tests were carried out at normal loads of 30 and 50 N with a sliding velocity of 1 m/s. Cumulative wear rate and coefficient of friction (μ) were calculated for all the cases. The worn-out surfaces were then examined by scanning electron microscopy analysis. Both the as-sprayed coatings exhibited typical splat morphology. The XRD analysis indicated the formation of Ni phase for the Ni-20Cr coating and Ni3Al phase for the Ni3Al coating. It has been concluded that the plasma-sprayed Ni-20Cr and Ni3Al coatings can be useful to reduce the wear rate of AISI 309 SS steel. The coatings were found to be adherent to the substrate steel during the wear tests. The plasma-sprayed Ni3Al coating has been recommended as a better choice to reduce the wear of AISI 309 SS steel, in comparison with the Ni-20Cr coating.

  18. Proton spectroscopy of 48Ni, 46Fe, and 44Cr

    CERN Document Server

    Pomorski, M; Dominik, W; Grzywacz, R; Stolz, A; Baumann, T; Berryman, J S; Czyrkowski, H; Dąbrowski, R; Fijałkowska, A; Ginter, T; Johnson, J; Kamiński, G; Larson, N; Liddick, S N; Madurga, M; Mazzocchi, C; Mianowski, S; Miernik, K; Miller, D; Paulauskas, S; Pereira, J; Rykaczewski, K P; Suchyta, S

    2014-01-01

    Results of decay spectroscopy on nuclei in vicinity of the doubly magic 48Ni are presented. The measurements were performed with a Time Projection Chamber with optical readout which records tracks of ions and protons in the gaseous volume. Six decays of 48Ni including four events of two-proton ground-state radioactivity were recorded. An advanced reconstruction procedure yielded the 2p decay energy for 48Ni of Q2p = 1.29(4) MeV. In addition, the energy spectra of \\b{eta}-delayed protons emitted in the decays of 44Cr and 46Fe, as well as half-lives and branching ratios were determined. The results were found to be consistent with the previous measurements made with Si detectors. A new proton line in the decay of 44Cr corresponding to the decay energy of 760 keV is reported. The first evidence for the \\b{eta}2p decay of 46 Fe, based on one clear event, is shown.

  19. Effects of helium injection mode on void formation in Fe-Ni-Cr alloys

    Science.gov (United States)

    Kimoto, T.; Lee, E. H.; Mansur, L. K.

    1988-09-01

    The effect of the helium injection mode on void formation during ion irradiation of the pure solution-annealing alloys Fe-15Ni-7Cr, Fe-35Ni-7Cr, Fe-45Ni-7Cr, Fe-10Ni-13Cr, Fe-40Ni-13Cr, Fe-45Ni-15Cr was examined. Ion irradiation was carried out with 4 MeV Ni ions at 948 K to doses of 30 to 100 dpa with: (1) no helium injection, (2) simultaneous helium injection and (3) helium preinjection and aging. Swelling variation with helium injection differed among the 7Cr alloys and 13-15Cr alloys. Only the simultaneous helium injection mode produced a bimodal cavity size distribution in the high Ni alloys. The critical radius, as estimated from the cavity size distributions appears to have increased with increasing dose, but no clear variation of the critical radius with composition was observed. Helium preinjection and one-hour aging at 948 K formed helium bubbles along the residual dislocations, while subsequent Ni irradiation caused void formation along the dislocation lines. The calculated helium concentration deduced from observable helium bubbles was low compared with the injected helium concentration in the alloys containing higher Ni and lower Cr.

  20. Sliding wear behaviors of electrodeposited Ni composite coatings containing micrometer and nanometer Cr particles

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guo-gang; ZHOU Yue-bo; ZHANG Hai-jun

    2009-01-01

    Micrometer and nanometer Cr particles were co-deposited with Ni by electroplating from a nickel sulfate bath containing a certain content of Cr particles. Cr microparticles are in a size range of 1-5 (m and Cr nanoparticles have an average size of 40 nm. The friction and the wear performance of the co-deposited Ni-Cr composite coatings were comparatively evaluated by sliding against Si3N4 ceramic balls under non-lubricated conditions. It is found that the incorporation of Cr particles enhances the microhardness and wear resistance of Ni coatings. The wear resistance of Ni composite coating containing Cr nanoparticles is higher than that of the Ni composite coating containing Cr microparticles with a comparable Cr particle content. The co-deposition of smaller nanometer Cr particles with Ni effectively reduces the size of Ni crystals and significantly increases the hardness of the composite coatings due to grain-refinement strengthening and dispersion-strengthening, resulting in a significant improvement of wear resistance of the Ni-Cr nanocomposite coatings.

  1. Effect of Cr and Ni on diffusion bonding of Fe3Al with steel

    Indian Academy of Sciences (India)

    Wang Juan; Li Yajiang; Ma Haijun

    2005-02-01

    Microstructure at the diffusion bonding interface between Fe3Al and steel including Q235 low carbon steel and Cr18–Ni8 stainless steel was analysed and compared by means of scanning electron microscopy and transmission electron microscopy. The effect of Cr and Ni on microstructure at the Fe3Al/steel diffusion bonding interface was discussed. The experimental results indicate that it is favourable for the diffusion of Cr and Ni at the interface to accelerate combination of Fe3Al and steel during bonding. Therefore, the width of Fe3Al/Cr18–Ni8 interface transition zone is more than that of Fe3Al/Q235. And Fe3Al dislocation couples with different distances, even dislocation net occurs at the Fe3Al/Cr18–Ni8 interface because of the dispersive distribution of Cr and Ni in Fe3Al phase.

  2. Modeling Study of Cyclic Oxidation Behavior of NiAl and NiCr Alloys

    Science.gov (United States)

    Peng, X. J.; Chen, K. Y.; Liu, R.; Liang, M.

    2014-12-01

    The cyclic oxidation behavior of four high-temperature alloys (two NiAl alloys and two NiCr alloy) is studied utilizing an existing micromechanics-based model, in which Al2O3 and Cr2O3 are formed on the alloys as protective layers. For each alloy, the model parameters are determined based on one `complete' experimental curve of weight change, which is obtained under a high-temperature cyclic oxidation test where the weight change experiences a maximum value and then drops down to a zero point. The model is first tested on two metals which have experimental data available for comparison. It is found that the model parameter, oxide crack density exponent, can be assumed constant within a range of high temperature for each metal, thus with the `complete' experimental curve of weight change, the model can predict the oxidation behavior of the metal at different temperatures. The determination of model parameters, accuracy, and limitations of the model for NiAl and NiCr alloys is analyzed and discussed.

  3. Sintering behaviour and mechanical properties of Cr3C2–NiCr cermets

    Indian Academy of Sciences (India)

    A Özer; Y K Tür

    2013-10-01

    Cr3C2–NiCr cermets are used as metal cutting tools due to their relatively high hardness and low sintering temperatures. In this study, a powder mixture consisting of 75 wt% Cr3C2–25 wt% NiCr was sintered at four different temperatures and characterized for itsmicrostructure and mechanical properties. The highest relative density obtained was 97% when sintered at 1350 °C. As the relative density increased, elastic modulus, transverse rupture strength, fracture toughness and hardness of the samples reached to a maximum of 314 GPa, 810 MPa, 10.4 MPa.m1/2 and 11.3 GPa, respectively. However, sintering at 1400 °C caused further grain growth and pore coalescence which resulted in decreasing density and degradation of all mechanical properties. Fracture surface investigation showed that the main failure mechanism was the intergranular fracture of ceramic phase accompanied by the ductile fracture of the metal phase which deformed plastically during crack propagation and enhanced the fracture toughness.

  4. Heat-to-Heat Variation in Creep Life and Fundamental Creep Rupture Strength of 18Cr-8Ni, 18Cr-12Ni-Mo, 18Cr-10Ni-Ti, and 18Cr-12Ni-Nb Stainless Steels

    Science.gov (United States)

    Abe, Fujio

    2016-06-01

    Metallurgical factors causing the heat-to-heat variation in time to rupture have been investigated for 300 series stainless steels for boiler and heat exchanger seamless tubes, 18Cr-8Ni (JIS SUS 304HTB), 18Cr-12Ni-Mo (JIS SUS 316HTB), 18Cr-10Ni-Ti (JIS SUS321 HTB), and 18Cr-12Ni-Nb (JIS SUS 347HTB), at 873 K to 1023 K (600 °C to 750 °C) using creep rupture data for nine heats of the respective steels in the NIMS Creep Data Sheets. The maximum time to rupture was 222,705.3 hours. The heat-to-heat variation in time to rupture of the 304HTB and 316HTB becomes more significant with longer test durations at times above ~10,000 hours at 973 K (700 °C) and reaches to about an order of magnitude difference between the strongest and weakest heats at 100,000 hours, whereas that of the 321HTB and 347HTB is very large of about an order of magnitude difference from a short time of ~100 hours to long times exceeding 100,000 hours at 873 K to 973 K (600 °C to 700 °C). The heat-to-heat variation in time to rupture is mainly explained by the effect of impurities: Al and Ti for the 304HTB and 316HTB, which reduces the concentration of dissolved nitrogen available for the creep strength by the formation of AlN and TiN during creep, and boron for the 347HTB, which enhances fine distributions of M23C6 carbides along grain boundaries. The heat-to-heat variation in time to rupture of the 321HTB is caused by the heat-to-heat variation in grain size, which is inversely proportional to the concentration of Ti. The fundamental creep rupture strength not influenced by impurities is estimated for the steels. The 100,000 hours-fundamental creep rupture strength of the 347HTB steel is lower than that of 304HTB and 316HTB at 873 K and 923 K (600 °C and 650 °C) because the slope of stress vs time to rupture curves is steeper in the 347HTB than in the 304HTB and 316HTB. The 100,000 hours-fundamental creep rupture strength of the 321HTB exhibits large variation depending on grain size.

  5. Heat-to-Heat Variation in Creep Life and Fundamental Creep Rupture Strength of 18Cr-8Ni, 18Cr-12Ni-Mo, 18Cr-10Ni-Ti, and 18Cr-12Ni-Nb Stainless Steels

    Science.gov (United States)

    Abe, Fujio

    2016-09-01

    Metallurgical factors causing the heat-to-heat variation in time to rupture have been investigated for 300 series stainless steels for boiler and heat exchanger seamless tubes, 18Cr-8Ni (JIS SUS 304HTB), 18Cr-12Ni-Mo (JIS SUS 316HTB), 18Cr-10Ni-Ti (JIS SUS321 HTB), and 18Cr-12Ni-Nb (JIS SUS 347HTB), at 873 K to 1023 K (600 °C to 750 °C) using creep rupture data for nine heats of the respective steels in the NIMS Creep Data Sheets. The maximum time to rupture was 222,705.3 hours. The heat-to-heat variation in time to rupture of the 304HTB and 316HTB becomes more significant with longer test durations at times above ~10,000 hours at 973 K (700 °C) and reaches to about an order of magnitude difference between the strongest and weakest heats at 100,000 hours, whereas that of the 321HTB and 347HTB is very large of about an order of magnitude difference from a short time of ~100 hours to long times exceeding 100,000 hours at 873 K to 973 K (600 °C to 700 °C). The heat-to-heat variation in time to rupture is mainly explained by the effect of impurities: Al and Ti for the 304HTB and 316HTB, which reduces the concentration of dissolved nitrogen available for the creep strength by the formation of AlN and TiN during creep, and boron for the 347HTB, which enhances fine distributions of M23C6 carbides along grain boundaries. The heat-to-heat variation in time to rupture of the 321HTB is caused by the heat-to-heat variation in grain size, which is inversely proportional to the concentration of Ti. The fundamental creep rupture strength not influenced by impurities is estimated for the steels. The 100,000 hours-fundamental creep rupture strength of the 347HTB steel is lower than that of 304HTB and 316HTB at 873 K and 923 K (600 °C and 650 °C) because the slope of stress vs time to rupture curves is steeper in the 347HTB than in the 304HTB and 316HTB. The 100,000 hours-fundamental creep rupture strength of the 321HTB exhibits large variation depending on grain size.

  6. Effect of thermal spray processes on microstructures and properties of Ni-20%Cr coatings

    OpenAIRE

    Pittaya Kuntasudjai; Nuchjira Dejang; Sukanda Jiansirisomboon

    2006-01-01

    Ni-20%Cr coatings were produced using different thermal spray techniques, which were spray and fuse, flame spray and arc spray. The Ni-20%Cr powder was sprayed onto a mild steel substrate using the spray and fuse and the flame spray systems, while the Ni-20%Cr wire was sprayed using the arc spray system. SEM microstructures of the coatings suggested the spraying conditions used were able to produce dense microstructures. However, the microstructure of the arc sprayed coatings showed fine lame...

  7. Effect of Cr/C Ratio on Microstructure and Corrosion Performance of Cr3C2-NiCr Composite Fabricated by Laser Processing

    Science.gov (United States)

    Lou, Deyuan; Liu, Dun; He, Chunlin; Bennett, Peter; Chen, Lie; Yang, Qibiao; Fearon, Eamonn; Dearden, Geoff

    2016-01-01

    The present study focuses on the effect of different Cr/C ratios on the microstructure, microhardness, and corrosion resistance of Ni-based laser clad hardfacings, reinforced by in situ synthesized chromium carbide particles. Cr3C2-NiCr composites have been laser processed with graphite/Cr/Ni powder blends with varying Cr/C ratios. Following phase analysis (x-ray diffraction) and microstructure investigation (scanning electron microscopy; energy dispersive x-ray analysis; transmission electron microscopy), the solidification of laser melt pool is discussed, and the corrosion resistances are examined. Several different zones (planar, dendritic, eutectic and re-melt zone) were formed in these samples, and the thicknesses and shapes of these zones vary with the change of Cr/C ratio. The sizes and types of carbides and the content of reserved graphite in the composites change as the Cr/C ratio varies. With the content of carbides (especially Cr3C2) grows, the microhardness is improved. The corrosive resistance of the composites to 0.2M H2SO4 aqueous solution decreases as the Cr/C ratio reduces owing to not only the decreasing Cr content in the NiCr matrix but also the galvanic corrosion formed within the carbide and graphite containing Ni matrix.

  8. Synthesis of colloidal dispersions of NiAl, ZnAl, NiCr, ZnCr, NiFe, and MgFe hydrotalcite-like nanoparticles.

    Science.gov (United States)

    Bellezza, Francesca; Nocchetti, Morena; Posati, Tamara; Giovagnoli, Stefano; Cipiciani, Antonio

    2012-06-15

    Colloidal aqueous dispersions of nanometric NiAl, ZnAl, NiCr, ZnCr, NiFe, and MgFe hydrotalcite-like compounds were prepared in a water/cetyltrimethylammonium bromide/n-butanol/isooctane microemulsion. Particle sizes were analyzed with different techniques, and the results confirm dimensions between 10 and 30 nm, except for ZnAl-HTlc (150-200 nm). A good colloidal stability of HTlc-NPs aqueous dispersions, investigated with DLS and Pz measurements, was obtained without the need for any stabilizing agent. SEM images clearly showed that the obtained HTlc posses a high tendency to spontaneously form homogeneous and dense stacking of plate-like HTlc crystals directly from aqueous solution, giving rise to the developing of functional materials in optical, electrical and magnetic fields. PMID:22459023

  9. Fabrication of CdTe/NiTe films on Ni foils by radio-frequency magnetron sputtering method

    International Nuclear Information System (INIS)

    Highlights: • The effects of Ts on CdTe deposited on Ni by magnetron sputtering is investigated. • An effective method is studied of making CdTe/NiTe without post-treatment. • As-prepared CdTe/NiTe raised optical absorption and PEC properties. • Pre-deposited Te can react with Ni to generate NiTe at Ts = 350 °C. - Abstract: Cadmium Telluride (CdTe) semiconductor thin films are fabricated on flexible Ni foil substrates using radio-frequency (RF) magnetron sputtering under different substrate temperatures. The crystal structure and properties of the prepared functional thin films were characterized with series analysis technologies. The characterization results revealed that Nickel Telluride (NiTe) phase formatted at the interface of CdTe and Ni substrate when substrate temperature (Ts) is 450 °C. Specially, XRD results demonstrated that CdTe/NiTe films could also be obtained by pre-depositing Te film on Ni and reducing Ts to 350 °C. The investigation on optical and photoelectrochemical (PEC) properties of the products illustrated that compact CdTe/NiTe films had improved the absorption in the visible region. Furthermore, PEC measurements indicated that CdTe/NiTe/Ni photoelectrode can have a promising application in photovoltaic devices

  10. Hydroxyapatite coating on pretreated CoNiCrMo prosthesis

    Institute of Scientific and Technical Information of China (English)

    WANG Tao; A. Dorner-Reisel

    2005-01-01

    In order to improve the quality of the bio-active coating on medical grade CoNiCrMo substrate, hydroxyapatite(HA) coatings were produced via low-temperature dip-coating route on substrates treated using various surface pre-treating methods. The surface and cross-sectional morphologies of HA coatings were observed by SEM, as well as the bonding strength between coatings and substrates after different pre-treatments were characterized according to ASTM C633. The low-temperature HA dip-coating method with the substrate merely oxidized at 600℃ can provide a high quality HA coating for CoNiCrMo, of which the bonding strength reaches (58±5)MPa, higher than that of the clinically used HA coatings on Ti-alloys produced via plasma spray route, as well as a HA coating with full crystallinity and high phase-purity, which is more in-vivo stable than plasma sprayed HA coating.

  11. Selective internal oxidation in Ni-Cr-Fe alloys during exposure in hydrogenated steam

    International Nuclear Information System (INIS)

    Selective internal oxidation (SIO) in hydrogenated steam was observed to occur in high-purity Ni-Cr-Fe alloys. Five alloys (Ni-9Fe, Ni-5Cr, Ni-5Cr-9Fe, Ni-16Cr-9Fe and Ni-30Cr-9Fe) were exposed to hydrogen-to-water vapor partial pressure ratios (PPR) of 0.09 and 0.5 at 400oC. The Ni-9Fe, Ni-5Cr and Ni-5Cr-9Fe alloys formed a uniform Ni(OH)2 film at a PPR up to 0.09 and the higher chromium alloys formed chromium-rich oxide films over the entire PPR range studied. Intergranular oxides formed by oxygen diffusion down the grain boundary. The formation of grain boundary chromium oxides is correlated with cracked grain boundary fraction and crack growth rate at 400oC. The observation of grain boundary oxides in stressed and unstressed samples as well as the influence of alloy content on intergranular (IG) cracking and oxidation support SIO as a mechanism for intergranular stress corrosion cracking (IGSCC). (author)

  12. A New Method to Produce Ni-Cr Ferroalloy Used for Stainless Steel Production

    Science.gov (United States)

    Chen, Pei-Xian; Chu, Shao-Jun; Zhang, Guo-Hua

    2016-08-01

    A new electrosilicothermic method has been proposed in the present paper to produce Ni-Cr ferroalloy, which can be used for the production of 300 series stainless steel. Based on this new process, the Ni-Si ferroalloy is first produced as the intermediate alloy, and then the desiliconization process of Ni-Si ferroalloy melt with chromium concentrate is carried out to generate Ni-Cr ferroalloy. The silicon content in the Ni-Si ferroalloy produced in the submerged arc furnace should be more than 15 mass% (for the propose of reducing dephosphorization), in order to make sure the phosphorus content in the subsequently produced Ni-Cr ferroalloy is less than 0.03 mass%. A high utilization ratio of Si and a high recovery ratio of Cr can be obtained after the desiliconization reaction between Ni-Si ferroalloy and chromium concentrate in the electric arc furnace (EAF)-shaking ladle (SL) process.

  13. DSC Analysis Of Order–Disorder Transition In Ni3Al Based Alloys From Ni-Al-Cr System

    Directory of Open Access Journals (Sweden)

    Maciąg T.

    2015-09-01

    Full Text Available Ni-Al-Cr system is significant for industrial alloys based on intermetallic phase Ni3Al, that crystallizes in crystal lattice L12. It is indicated as γ′, contrary to disordered phase γ which occurs with addition of chromium. DSC analysis was performed on alloys of chemical composition from Ni75Al25÷Ni75Cr25 range of Ni-rich part of Ni-Al-Cr system. In addition, few measurements were conducted using DTA method. Based on curves registered, it was possible to identify characteristic temperature during heating and cooling of the sample. It corresponds to existence of phase boundary γ′+γ / γ in examined alloys. Results of thermal analysis were compared with results obtained with other method performed by authors which is solution calorimetric method.

  14. Using hyperaccumulator plants to phytoextract soil Ni and Cd.

    Science.gov (United States)

    Chaney, Rufus L; Angle, J Scott; McIntosh, Marla S; Reeves, Roger D; Li, Yin-Ming; Brewer, Eric P; Chen, Kuang-Yu; Roseberg, Richard J; Perner, Henrike; Synkowski, Eva Claire; Broadhurst, C Leigh; Wang, S; Baker, Alan J M

    2005-01-01

    Two strategies of phytoextraction have been shown to have promise for practical soil remediation: domestication of natural hyperaccumulators and bioengineering plants with the genes that allow natural hyperaccumulators to achieve useful phytoextraction. Because different elements have different value, some can be phytomined for profit and others can be phytoremediated at lower cost than soil removal and replacement. Ni phytoextraction from contaminated or mineralized soils offers economic return greater than producing most crops, especially when considering the low fertility or phytotoxicity of Ni rich soils. Only soils that require remediation based on risk assessment will comprise the market for phytoremediation. Improved risk assessment has indicated that most Zn + Cd contaminated soils will not require Cd phytoextraction because the Zn limits practical risk from soil Cd. But rice and tobacco, and foods grown on soils with Cd contamination without corresponding 100-fold greater Zn contamination, allow Cd to readily enter food plants and diets. Clear evidence of human renal tubular dysfunction from soil Cd has only been obtained for subsistence rice farm families in Asia. Because of historic metal mining and smelting, Zn + Cd contaminated rice soils have been found in Japan, China, Korea, Vietnam and Thailand. Phytoextraction using southern France populations of Thlaspi caerulescens appears to be the only practical method to alleviate Cd risk without soil removal and replacement. The southern France plants accumulate 10-20-fold higher Cd in shoots than most T. caerulescens populations such as those from Belgium and the UK. Addition of fertilizers to maximize yield does not reduce Cd concentration in shoots; and soil management promotes annual Cd removal. The value of Cd in the plants is low, so the remediation service must pay the costs of Cd phytoextraction plus profits to the parties who conduct phytoextraction. Some other plants have been studied for Cd

  15. Luminescence Dynamics of Cr2+ in CdTe and Cd0.55Mn0.45Te

    Science.gov (United States)

    Bluiett, A.; Hommerich, U.; Seo, J. T.; Shah, R.; Trivedi, S. B.; Kutcher, S. W.; Chen, R. J.; Wang, C. C.; Zong, H.

    2001-04-01

    Cr^2+ in tetrahedrally coordinated CdTe and Cd_0.55Mn_0.45Te crystals are under investigation as potential host materials for tunable, mid-infrared (MIR) lasers. The small crystal field splitting of the free ion energy levels of Cr^2+ induces absorption (1900nm) and stokes shifted emission (2000nm-3000nm) bands in the MIR. Also, the relatively large ionic mass and tetrahedral environment of Cr^2+ in CdTe and Cd_0.55Mn_0.45Te have shown that the luminescence efficiency at room temperature is approximately 72100luminescence lifetime decreases rapidly, which suggest that the effects of nonradiative decay increases. The decay dynamics of Cr^2+ in CdTe and Cd_0.55Mn_0.45Te will be described with the model of Struck and Fonger for the non-radiative decay rate.

  16. Laser Remelting of Plasma Sprayed NiCrA1Y and NiCrAlY-A12O3 Coatings

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Two types of plasma sprayed coatings (NiCrAIY and NiCrAIY-AI2O3) were remelted by a 5 kW cw CO2 laser. With increasing laser power and decreasing traverse speed in the ranges of 200~700 W and 5~30 mm/s respectively, the melted track grew in width and depth. In the optimum range of laser parameters, a homogeneous remelted layer without voids, cavities, unmelted particles and microcracks was formed. On the surface of remelted layers, AI2O3 and YAIO3 were detected.As a result of isothermal oxidation tests, weight gains of laser remelted coatings were obviously lower than that only plasma sprayed, especially laser remelted NiCrAIY-AI2O3 coatings. The effects of laser remelting and incorporation of Al2O3 second phase in NiCrAIY matrix on high temperature oxidation resistance were discussed.

  17. Pitting Corrosion of Ni3(Si,Ti+2Cr Intermetallic Compound at Various Chloride Concentrations

    Directory of Open Access Journals (Sweden)

    Gadang Priyotomo

    2014-05-01

    Full Text Available The pitting corrosion of Ni3(Si,Ti with 2 at% Cr containing two regions of a Ni3(Si,Ti single-phase of L12 structure and a mixture phase of of (L12 +Niss was investigated as function of chloride concentrations by using a polarization method, scanning electron microscope and energy dispersive X-Ray spectroscopy in neutral sodium chloride solutions at 293 K.  The pitting corrosion of Ni3(Si,Ti with and without the addition of aluminium and type C276 alloy were also studied under the same experimental condition for the comparison.  The pitting potential obtained for the Ni3(Si,Ti with 2 at% Cr decreased with increasing chloride concentration.  The specific pitting potentials and the pitting potentials were decreased in the order of C276 alloy > Ni3(Si,Ti > Ni3(Si,Ti + 2Cr > Ni3(Si,Ti + 4Al, which means that the pitting corrosion resistance of Ni3(Si,Ti with 2 at% Cr was higher than Ni3(Si,Ti with 4 at% Al, but lower than that of Ni3(Si,Ti.  A critical chloride concentration of Ni3(Si,Ti with 2 at% Cr was found to be higher than that of Ni3(Si,Ti with at% Al. In addition, the presence of high concentration for oxygen indicates the occurrence of pit formation.

  18. Characterization of transition behavior in SA508 Gr.4N Ni-Cr-Mo low alloy steels with microstructural alteration by Ni and Cr contents

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ki-Hyoung; Park, Sang-gyu [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Nuclear Materials Research Division, KAERI, Daejeon 305-353 (Korea, Republic of); Kim, Min-Chul, E-mail: mckim@kaeri.re.kr [Nuclear Materials Research Division, KAERI, Daejeon 305-353 (Korea, Republic of); Lee, Bong-Sang [Nuclear Materials Research Division, KAERI, Daejeon 305-353 (Korea, Republic of); Wee, Dang-Moon [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of)

    2011-11-25

    Highlights: {yields} We offer information for determining optimum alloying contents of SA508 Gr.4N steel. {yields} This study shows improvement of toughness with increasing Ni and Cr contents. {yields} Ni content is more effective on the impact toughness than on the fracture toughness. {yields} Cr content is more effective on the fracture toughness. {yields} We offer detailed information on relationship between toughness and microstructure. - Abstract: SA508 Gr.4N Ni-Cr-Mo low alloy steel, in which Ni and Cr contents are higher than in commercial reactor pressure vessel (RPV) steels, may be a candidate RPV material with the improved strength and toughness due to its tempered martensitic microstructure. This study aims at assessing the effects of microstructural factors with alloying element contents on the transition properties of Ni-Cr-Mo low alloy steels. Model alloys with different Ni and Cr contents were fabricated and their Charpy impact toughness and fracture toughness were examined in the transition region according to ASTM E23 and E1921 standard procedures, respectively. The test results showed extensive improvements of both impact toughness and fracture toughness with increasing Ni and Cr contents. However, Ni content was more effective on the impact toughness than on the fracture toughness, while Cr content was more effective on the fracture toughness. In order to identify a difference in effects of alloying elements contents on the fracture toughness and impact toughness, the relations between the transition properties and the scale of the microstructural features such as packets and carbides are discussed in detail.

  19. Magnetni nanodelci na osnovi zlitin NiCu in NiCr za uporabo v samoregulativni magnetni hipertermiji

    OpenAIRE

    Stergar, Janja

    2014-01-01

    V doktorskem delu smo obravnavali sintezo in karakterizacijo nanodelcev zlitin NiCu in NiCr za uporabo v samoregulativni magnetni hipertermiji. V prvem delu smo pripravili zlitine NiCu in NiCr s tremi različnimi sinteznimi postopki: mehansko mletje, sinteza s pomočjo mikroemulzij in sol-gel metoda, pri čemer smo preučevali reakcijske pogoje posamezne sinteze. Sledila je karakterizacija pridobljenih zlitin s pomočjo rentgenske praškovne difrakcije, transmisijske elektronske mikroskopije, ma...

  20. NiAl-based Polyphase in situ Composites in the NiAl-Ta-X (X = Cr, Mo, or V) Systems

    Science.gov (United States)

    Johnson, D. R.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.

    1995-01-01

    Polyphase in situ composites were generated by directional solidification of ternary eutectics. This work was performed to discover if a balance of properties could be produced by combining the NiAl-Laves phase and the NiAl-refractory metal phase eutectics. The systems investigated were the Ni-Al-Ta-X (X = Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and the eutectic composition, temperature, and morphology were determined. The ternary eutectic systems examined were the NiAl-NiAlTa-(Mo, Ta), NiAl-(Cr, Al) NiTa-Cr, and the NiAl-NiAlTa-V systems. Each eutectic consists of NiAl, a C14 Laves phase, and a refractory metal phase. Directional solidification was performed by containerless processing techniques in a levitation zone refiner to minimize alloy contamination. Room temperature fracture toughness of these materials was determined by a four-point bend test. Preliminary creep behavior was determined by compression tests at elevated temperatures, 1100-l400 K. Of the ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr, Al)NiTa-Cr eutectic was intermediate between the values of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.

  1. The crystal structure of (Fe4Cr4Ni)9C4

    Institute of Scientific and Technical Information of China (English)

    SHI; Nicheng; MA; Zhesheng; XIONG; Ming; DAI; Mingquan; BA

    2005-01-01

    (Fe4Cr4Ni)9C4 is a metal carbide mineral formed by combination of Fe, Cr and Ni with C. It occurs in a chromite deposit in the Luobusha ophiolite, Tibet. Based on the determination of its crystal structure, the empirical formula is (Fe4.12Cr3.84Ni0.96)8.92C3.70 and the simplified formula is (Fe4Cr4Ni)4C9. The mineral is hexagonal with a = 1.38392(2) nm, c = 0.44690(9) nm,space group P63 m c, Z=6 and the calculated specific gravity Dx = 7.089 g/cm3. Fe, Cr and Ni occupy different crystallographic sites and their coordination numbers are approximately 12,forming an alternate stacking sequence of flat and puckered layers along the c axis. Some metallic atoms have a defect structure. The interatomic distances of Fe, Cr and Ni are 0.2525-0.2666 nm, and the distances between Fe, Cr, Ni and C are 0.1893-0.2169 nm. The coordination number of carbon is 6. It occurs in interstices of the metallic atoms Fe, Cr and Ni to form trigonal-prismatically coordinated polyhedra. These coordination polyhedra are linked with each other via shared corners or shared edges into a new type of metal carbide structure.

  2. Synthesis and Characterization of NiCr Self-assembled Nanorings

    NARCIS (Netherlands)

    Serdio, Victor M.; Gracia-Pinilla, Miguel A.; Velumani, S.; Perez-Tijerina, Eduardo G.; Wiel, van der Wilfred G.

    2010-01-01

    Formation of NiCr nanorings out of 2-3 nm NiCr nanoparticles prepared by DC magnetron sputtering with inert gas condensation is reported. An RF quadrupole mass filter has been used to get the particle size distribution and control the particle size in the plasma stream of grown material. The deposit

  3. Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

    NARCIS (Netherlands)

    Bojack, A.; Zhao, L.; Morris, P.F.; Sietsma, J.

    2016-01-01

    The influence of austenitization treatment of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) on austenite formation during reheating and on the fraction of austenite retained after tempering treatment is measured and analyzed. The results show the formation of austenite in two stage

  4. Microstructural studies of nanocomposite thin films of Ni/CrN prepared by reactive magnetron sputtering.

    Science.gov (United States)

    Kuppusami, P; Thirumurugesan, R; Divakar, R; Kataria, S; Ramaseshan, R; Mohandas, E

    2009-09-01

    Synthesis and characterization of nanocomposites of Ni/CrN thin films prepared by DC magnetron sputtering from a target of 50 wt.%Ni-50 wt.%Cr is investigated. The films prepared as a function of nitrogen flow rate and substrate temperature showed that the films contained Ni and CrN phases with crystallite sizes in the nanometer range. Measurement of nanomechanical properties of the composite films exhibited a significant decrease in the values of hardness and Young's modulus than those of pure CrN films. PMID:19928270

  5. Oxidation behavior of TD-NiCr in a dynamic high temperature environment

    Science.gov (United States)

    Tenney, D. R.; Young, C. T.; Herring, H. W.

    1974-01-01

    The oxidation behavior of TD-NiCr has been studied in static and high-speed flowing air environments at 1100 and 1200 C. It has been found that the stable oxide morphologies formed on the specimens exposed to the static and dynamic environments were markedly different. The faceted crystal morphology characteristic of static oxidation was found to be unstable under high-temperature, high-speed flow conditions and was quickly replaced by a porous NiO 'mushroom' type structure. Also, it was found that the rate of formation of CrO3 from Cr2O3 was greatly enhanced by high gas velocity conditions. The stability of Cr2-O3 was found to be greatly improved by the presence of an outer NiO layer, even though the NiO layer was very porous. An oxidation model is proposed to explain the observed microstructures and overall oxidation behavior of TD-NiCr alloys.

  6. Magnetic and Structural Properties in Co/Cu/Co Sandwiches with Ni and Cr Buffer Layers

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The magnetic and structural properties in Co/Cu/Co sandwiches with Ni and Cr buffer layers were investigated. It was found that the coercivity in Ni layer buffered samples decreases with increasing Ni layer thickness, while that in Cr layer buffered ones increases with increasing Cr layer thickness, leading to a large difference in field sensitivity of their giant magnetoresistance (GMR) properties. X-ray diffraction and high resolution transmission electron microscope images exhibited that there is a strong fcc (111) texture in the samples with Ni buffer layer. But there are only randomly oriented polycrystalline grains in Cr buffered sandwiches. According to atomic force microscope topography, the surface roughness of Cr buffered sandwiches is smaller than that of Ni buffered ones. It is demonstrated that buffer layer influences both magnetic and structural properties in Co/Cu/Co sandwiches as well as their GMR characteristics.

  7. Emittance of TD-NiCr after simulated reentry

    Science.gov (United States)

    Clark, R. K.; Dicus, D. L.; Lisagor, W. B.

    1978-01-01

    The effects of simulated reentry heating on the emittance of TD-NiCr were investigated. Groups of specimens with three different preconditioning treatments were exposed to 6, 24, and 30 half-hour simulated reentry exposure cycles in a supersonic arc tunnel at each of three conditions intended to produce surface temperatures of 1255, 1365, and 1475 K. Emittance was determined at 1300 K on specimens which were preconditioned only and specimens after completion of reentry simulation exposure. Oxide morphology and chemistry were studied by scanning electron microscopy and X-ray diffraction analysis. A consistent relationship was established between oxide morphology and total normal emittance. Specimens with coarser textured oxides tended to have lower emittances than specimens with finer textured oxides.

  8. Density of liquid NiCoAlCr quarternary alloys measured by modified sessile drop method

    Institute of Scientific and Technical Information of China (English)

    FANG Liang; ZHANG Shu-fang; XIAO Feng; YANG Ling-chuan; DONG Jian-xin; CAO Chun-lan; TAO Zai-nan; K. MUKAI

    2006-01-01

    The densities of liquid NiCoAlCr quaternary alloys with a fixed molar ratio of Ni to Co to Al (x(Ni)-x(Co)-x(Al)≈73-12-15) which is close to the average value of the commercial Ni-based superalloys TMS75, INCO713, CM247LC and CMSX-4, and the mass fraction of chromium changes from 0 to 9% were measured by a modified sessile drop method. It is found that with increasing temperature and chromium concentration in the alloys, the densities of the liquid NiCoAlCr quaternary alloys decrease, whereas the molar volume of the liquid NiCoAlCr quaternary alloys increases. And the liquid densities of NiCoAlCr quaternary alloys calculated from the partial molar volumes of nickel, cobalt, aluminum and chromium in the corresponding Ni-bases binary alloys are in good agreement with the experimental ones, i.e. within the error tolerance range the densities of the liquid Ni-based multi-component alloys can be predicted from the partial volumes of elements in Ni-based binary alloys in liquid state. The molar volume of liquid NiCoAlCr binary alloy shows a negative deviation from the ideal linear mixing and the deviation changes small with the increase of chromium concentration at the same temperature.

  9. Evidence for the role of CR1 (CD35), in addition to CR2 (CD21), in facilitating infection of human T cells with opsonized HIV.

    Science.gov (United States)

    Delibrias, C C; Kazatchkine, M D; Fischer, E

    1993-08-01

    Complement activation by HIV results in the binding of C3 fragments to the gp160 complex and enhanced infection of C3 receptor-bearing target cells. We have studied complement-mediated enhancement of infection of the human CD4-positive T-cell line HPB-ALL which expresses the CR1 (CD35) and CR2 (CD21) receptors for C3. CR1 and CR2 are present on 15% and 40% of normal peripheral blood CD4-positive T lymphocytes respectively. Opsonization of the virus with complement resulted in a 3- to 10-fold enhancement of infection of HPB-ALL cells, as assessed by measuring the release of p24 antigen in culture supernatants throughout the culture period. Blockade of CR2 with cross-linked anti-CR2 monoclonal antibodies decreased infection to the level observed with unopsonized virus. Blocking CR1 reduced complement-mediated infection by 50-80%. Experiments using serum deficient in complement factor I demonstrated that CR1 mediates the interaction between opsonized virus and T cells in addition to its ability to serve as a cofactor for the cleavage of C3b into smaller fragments that interact with CR2. A requirement for CD4 in complement-mediated enhancement of infection was observed with HIV-1 Bru but not with HIV-1 RF. Thus, CR1 and CR2 contribute in an independent and complementary fashion to penetration of opsonized virus into complement receptor-expressing T cells. Involvement of CD4 in infection with opsonized virus depends on the viral strain. PMID:8346417

  10. Microstructure of laser clad Ni- Cr- Al- Hf alloy on a γ' strengthened ni- base superalloy

    Science.gov (United States)

    Singh, Jogender; Mazumder, J.

    1988-08-01

    Alloys and coatings for alloys for improved high temperature service life under aggressive atmo-spheres are of great contemporary interest. There is a general consensus that the addition of rare earths such as Hf will provide many beneficial effects for such alloys. The laser cladding technique was used to produce Ni-Cr-AI-Hf alloys with extended solid solution of Hf. A 10 kW CO2 laser with mixed powder feed was used for laser cladding. Optical, scanning electron (SEM) and scanning transmission electron (STEM) microscopy were employed to characterize the microstructure of alloys produced during laser cladding processes. Microstructural studies revealed grain refinement, considerable in-crease in solubility of Hf in the matrix, Hf-rich precipitates, and new metastable phases. The size and morphology of γ' (Ni3Al) phase were discussed in relation to its microchemistry and the laser processing conditions. This paper will report the microstructural development in this laser clad Ni-Cr-AI-Hf alloy.

  11. Hot Corrosion Behavior of Bare, Cr3C2-(NiCr) and Cr3C2-(NiCr) + 0.2wt.%Zr Coated SuperNi 718 at 900 °C

    Science.gov (United States)

    Mudgal, Deepa; Singh, Surendra; Prakash, Satya

    2015-01-01

    Corrosion in incinerators, power plants, and chemical industries are frequently encountered due to the presence of salts containing sodium, sulphur, and chlorine. To obviate this problem, bare and coated alloys were tested under environments simulating the conditions present inside incinerators and power plants. 0.2 wt.% zirconium powder was incorporated in the Cr3C2-(NiCr) coating powder. The original powder and Zr containing powder was sprayed on Superni 718 alloy by D-gun technique. The bare and coated alloys were tested under Na2SO4 + K2SO4 + NaCl + KCl and Na2SO4 + NaCl environment. The corrosion rate of specimens was monitored using weight change measurements. Characterization of the corrosion products has been done using FE-SEM/EDS and XRD techniques. Bare and coated alloys showed very good corrosion resistance under given molten salt environments. Addition of 0.2wt.%Zr in Cr3C2-25%(NiCr) coating further greatly reduced the oxidation rate as well as improved the adherence of oxide scale to the coating surface during the time of corrosion.

  12. Hot Corrosion Performance of AlO-CrO/NiCoCrAlYTa and AlO/NiCoCrAlYTa Coatings Deposited by Atmospheric Plasma Spraying

    Science.gov (United States)

    Tao, Chong; Wang, Lei; Cheng, Nailiang; Hu, Hengfa; Liu, Yang; Song, Xiu

    2016-04-01

    AlO-CrO/NiCoCrAlYTa and AlO/NiCoCrAlYTa coatings were deposited on 316L stainless steel substrate using atmospheric plasma spraying, respectively, in order to improve the oxidation and corrosion resistance. The hot corrosion performance of the coatings at 700 and 900 °C were studied, and the detailed microstructures and phase composition of the coatings were analyzed using x-ray diffraction, scanning electron microscope with energy dispersive spectrometer, and transmission electron microscope. The results show that both coatings are structurally featured by slatted layers, consisting of amorphous phase, Cr2O3, Ni3Al, and Al2O3. The hot corrosion resistance of AlO-CrO/NiCoCrAlYTa coating is better than that of AlO/NiCoCrAlYTa coating. This improvement is attributed to lower porosity and more compact Cr2O3 in AlO-CrO/NiCoCrAlYTa coating which performs better than Al2O3 in blocking further inward progress of corrosion and oxidization.

  13. Investigation of Ni and Cd electrokinetic removal from a sediment

    Directory of Open Access Journals (Sweden)

    Rajić Ljiljana

    2012-01-01

    Full Text Available In this paper we examine the efficacy of the enhanced electrokinetic remediation of a sediment from the Tamiš River contaminated with Ni and Cd. The moving anode technique and an increased cathodic compartment length were simultaneously used to enhance the technique. The removal efficacy increase appeared after the enhanced treatment for Ni (23% and Cd (73%. The increased cathodic compartment length successfully prevented OH- ions migration in the sediment. Finally, sediment classification according to different risk assessment methodologies indicates that further remediation is required even after the enhanced treatment. Here we indicate that enhanced electroremediation resulted in the removal of efficacy increase but it is highly influenced by sediment characteristics. [Projekat Ministarstva nauke Republike Srbije, br. TR 037004 i br. III 043005

  14. Behavior of NiCrAlY coating on the TC6 titanium alloy

    Institute of Scientific and Technical Information of China (English)

    Changqing Xia; Xiaomin Peng; Jia Li

    2008-01-01

    A NiCrAlY coating was deposited on the TC6 titanium substrate by arc ion plating (AIP). The structure and morphologies of the NiCrAlY coating were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the influence of vacuum heat treatment on the element diffusion behavior was studied. The results showed that the γ'-Ni3Al phase was precipitated on the NiCrAlY coating after heat treatment. The Ni3(Al,Ti), TiNi, and Ti2Ni intermetallic layers appeared at the interface from the outside to the inside at 700℃, and the thickness of the intermetallic layers increased with the increase in temperature. At 700℃ Ti and Ni were the major diffusion elements, and the diffusion of Cr was observed when the heat treatment temperature increased up to 870℃. The violent inward diffusion of Ni at 950℃ resulted in the degradation of the NiCrAlY coating.

  15. Inter-Diffusion between NiO Coating and the Oxide Scale on Fe-22Cr Alloy

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Mogensen, Mogens Bjerg; Linderoth, Søren;

    2003-01-01

    The effect of Ni and NiO coatings on Fe-22Cr during oxidation at 1173K in 1% H2O was examined with respect to scale microstructure for oxidation times between 0 and 504 hours. Upon oxidation of the as pre-treated Fe-22Cr, Cr2O3 and a spinel developed. Oxidation and inter-diffusion between the Ni...... coating and Fe-22Cr occurred simultaneously. The scale consisted of NiO, a Fe-Ni spinel and Cr2O3. For the NiO coated alloy, a thin spinel layer developed between the NiO coating and the Cr2O3 scale. The microstructures of the scales are discussed with respect to calculated isotherms in the Fe-Cr-O, Cr...

  16. Potentiostatic Oxide Growth Kinetics on Ni-Cr and Co-Cr Alloys: Potential and pH Dependences

    International Nuclear Information System (INIS)

    Oxide growth kinetics on the Ni-Cr-Fe alloy Inconel 600 and the Co-Cr alloy Stellite 6 under potentiostatic polarization have been investigated by current measurements augmented by ex-situ surface analyses. The results reveal a mechanism for metal oxidation and oxide formation that is common to both alloys. The reaction thermodynamics for the oxidation of a metal determine whether a certain metal oxidation can or cannot occur. However, the metal oxidation proceeds via two competing pathways, oxide formation and metal ion dissolution. At pH 10.6 where the solubilities of FeII, NiII or CoII species are near their minima, oxide formation is favoured over metal ion dissolution. As the oxide grows, the rate of metal oxidation decreases with time due to an increase in the electrochemical potential barrier. The oxide formation occurs sequentially; the conversion of the preformed Cr2O3 film to chromite (FeCr2O4 or CoCr2O4) proceeds before the next layers of Fe3O4/NiFe2O4 and NiO/Ni(OH)2 grow on Inconel 600, or CoO/Co(OH)2 grows on Stellite 6. The effect of a different EAPP is to limit the oxidation sequence. The pH does not directly affect the driving force for metal oxidation but it strongly influences the relative rates of oxide formation and metal dissolution, thereby affecting metal oxidation kinetics

  17. Mechanical properties of Fe-Ni-Cr-Si-B bulk glassy alloy

    International Nuclear Information System (INIS)

    The mechanical properties and crystallization behavior of new Fe-Ni-Cr-Si-B-based bulk glassy alloys were investigated. The suitability of the continuous roll casting method for the production of bulk metallic glass (BMG) sheets in such alloy systems was also examined. BMG samples (Fe-Ni-Cr-Si-B, Fe-Ni-Zr-Cr-Si-B, Fe-Ni-Zr-Cr-W-Si-B) in amorphous strip, cylindrical, and sheet forms were prepared through melt spinning, copper mold casting, and twin roll strip casting, respectively. Fe-Ni-Cr-Si-B alloy exhibited compressive strength of up to 2.93 GPa and plastic strain of about 1.51%. On the other hand, the Fe-Ni-Zr-Cr-Si-B, composite-type bulk sample with diameter of 2.0 mm showed remarkable compressive plastic strain of about 4.03%. The addition of zirconium was found to enhance the homogeneous precipitation of nanocrystalline less than 7 nm and to develop a hybrid-composite microstructure with increasing sample thickness. Twin roll strip casting was successfully applied to the fabrication of sheets in Fe-Ni-Cr-Si-B-based BMGs. The combined characteristics of high mechanical properties and ease of microstructure control proved to be promising in terms of the future progress of structural bulk amorphous alloys

  18. Standard Specification for Ni-Fe-Cr-Mo-Cu-N Low-Carbon Alloys (UNS N08925, UNS N08031, UNS N08354, and UNS N08926), and Cr-Ni-Fe-N Low-Carbon Alloy (UNS R20033) Bar and Wire, and Ni-Cr-Fe-Mo-N Alloy (UNS N08936) Wire

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2016-01-01

    Standard Specification for Ni-Fe-Cr-Mo-Cu-N Low-Carbon Alloys (UNS N08925, UNS N08031, UNS N08354, and UNS N08926), and Cr-Ni-Fe-N Low-Carbon Alloy (UNS R20033) Bar and Wire, and Ni-Cr-Fe-Mo-N Alloy (UNS N08936) Wire

  19. Ostwald ripening of decomposed phases in Cu-Ni-Cr alloys

    International Nuclear Information System (INIS)

    A study of the coarsening process of the decomposed phases was carried out in the Cu-34 wt.% Ni-4 wt.% Cr and Cu-45 wt.% Ni-10 wt.% Cr alloys using transmission electron microscopy. As aging progressed, the morphology of the coherent decomposed Ni-rich phase changed from cuboids to platelets aligned in the Cu-rich matrix directions. Prolonged aging caused the loss of coherency between the decomposed phases and the morphology of the Ni-rich phase changed to ellipsoidal. The variation of mean radius of the coherent decomposed phases with aging time followed the modified LSW theory for thermally activated growth in ternary alloy systems. The linear variation of the density number of precipitates and matrix supersaturation with aging time, also confirmed that the coarsening process followed the modified LSW theory in both alloys. The coarsening rate was faster in the symmetrical Cu-45 wt.% Ni-10 wt.% Cr alloy due to its higher volume fraction of precipitates. The activation energy for thermally activated growth was determined to be about 182 and 102 kJ mol-1 in the Cu-34 wt.% Ni-4 wt.% Cr and Cu-45 wt.% Ni-10 wt.% Cr alloys, respectively. The lower energy for the former alloy seems to be related to an increase in the atomic diffusion process as the chromium content increases. The size distributions of precipitates in the Cu-Ni-Cr alloys were broader and more symmetric than that predicted by the modified LSW theory for ternary alloys

  20. Electronic, Magnetic, and Redox Properties of [MFe(3)S(4)] Clusters (M = Cd, Cu, Cr) in Pyrococcus furiosus Ferredoxin.

    Science.gov (United States)

    Staples, Christopher R.; Dhawan, Ish K.; Finnegan, Michael G.; Dwinell, Derek A.; Zhou, Zhi Hao; Huang, Heshu; Verhagen, Marc F. J. M.; Adams, Michael W. W.; Johnson, Michael K.

    1997-12-01

    The ground- and excited-state properties of heterometallic [CuFe(3)S(4)](2+,+), [CdFe(3)S(4)](2+,+), and [CrFe(3)S(4)](2+,+) cubane clusters assembled in Pyrococcus furiosus ferredoxin have been investigated by the combination of EPR and variable-temperature/variable-field magnetic circular dichroism (MCD) studies. The results indicate Cd(2+) incorporation into [Fe(3)S(4)](0,-) cluster fragments to yield S = 2 [CdFe(3)S(4)](2+) and S = (5)/(2) [CdFe(3)S(4)](+) clusters and Cu(+) incorporation into [Fe(3)S(4)](+,0) cluster fragments to yield S = (1)/(2) [CuFe(3)S(4)](2+) and S = 2 [CuFe(3)S(4)](+) clusters. This is the first report of the preparation of cubane type [CrFe(3)S(4)](2+,+) clusters, and the combination of EPR and MCD results indicates S = 0 and S = (3)/(2) ground states for the oxidized and reduced forms, respectively. Midpoint potentials for the [CdFe(3)S(4)](2+,+), [CrFe(3)S(4)](2+,+), and [CuFe(3)S(4)](2+,+) couples, E(m) = -470 +/- 15, -440 +/- 10, and +190 +/- 10 mV (vs NHE), respectively, were determined by EPR-monitored redox titrations or direct electrochemistry at a glassy carbon electrode. The trends in redox potential, ground-state spin, and electron delocalization of [MFe(3)S(4)](2+,+) clusters in P. furiosus ferredoxin are discussed as a function of heterometal (M = Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Tl).

  1. Nanocomposite coatings based on Ti-N-Cr/Ni-Cr-B-Si-Fe, gained by two technologies

    Directory of Open Access Journals (Sweden)

    N.K. Erdybayeva

    2009-01-01

    Full Text Available The first results of manufacturing and investigations of a new type of nanocomposite protective coatings are presented. They were manufactured using a combination of two technologies: plasma-detonation coating deposition with the help of plasma jets and thin coating vacuum-arc deposition. We investigated structure, morphology, physical and mechanical properties of the coatings of 80-90 μm thickness, as well as defined the hardness, elastic Young modulus and their corrosion resistance in different media. Grain dimensions of the nanocomposite coatings on Ti-N-Cr base varied from 2.8 to 4 nm. The following phases and compounds formed as a result of plasma interaction with the thick coating surface were found in the coatings: Ti-N-Cr (200, (220, y-Ni3-Fe, a hexagonal Cr2-Ti, Fe3-Ni, (Fe, NiN and the following Ti-Ni compounds: Ti2Ni, Ni3Ti, Ni4Ti, etc. We also found that the nanocomposite coating microhardness increased to H = 31.6 ± 1.1 GPa. The Young elastic modulus was determined to be E = 319 ± 27 GPa – it was derived from the loading-unloading curves. The protective coating demonstrated the increased corrosion resistance in acidic and alkaline media in comparison with that of the stainless steel substrate.

  2. The change of NiCrBSi alloys’ phase composition after plasma spraying

    Directory of Open Access Journals (Sweden)

    A. Dudek

    2008-08-01

    Full Text Available Material for investigations was NiCrBSi powder for components’ coatings which improve their corrosion resistance as well as resistance to friction wear and erosion. Plasma spraying method was used to produce a coating with thickness of 300 μm on low-alloy steel which was then remelted with the base material. Using X-ray quality analysis, phase composition was determined for: NiCrBSi powder, obtained coating and the alloyed surface layer. Crystallinity degree was also calculated for NiCrBSi layer sprayed on the base material.

  3. Rates of corrosion of metals (Fe, Cr, Fe/Cr/Ni, 316 steel) in molten lithium hydroxide

    International Nuclear Information System (INIS)

    Molten LiOH corrodes Fe, Cr, 316 steel and other alloys over the temperature range 744 to 933 K according to the equations: 2Fe + 6LiOH -> LiFeO2 + Li5FeO4 + 3H2; 2Cr + 6LiOH -> 2LiCrO2 + 2Li2O + 3H2. The rates of corrosion were determined from the rate of evolution of hydrogen. Cr reacts most rapidly and corrosion rate increases with increasing Cr content and diminishing Ni content, so that 316 steel reacts fastest of the alloys which were investigated. Whereas oxygen inhibits the corrosion of 316 steel, addition of Li2O increases the rate. Inhibiting surface films of LiCrO2 and LiFeO2 appear to be disrupted by the formation of Li5FeO4, especially at the higher temperatures. (author)

  4. High Temperature Behavior of Cr3C2-NiCr Coatings in the Actual Coal-Fired Boiler Environment

    Science.gov (United States)

    Bhatia, Rakesh; Sidhu, Hazoor Singh; Sidhu, Buta Singh

    2015-03-01

    Erosion-corrosion is a serious problem observed in steam-powered electricity generation plants, and industrial waste incinerators. In the present study, four compositions of Cr3C2-(Ni-20Cr) alloy coating powder were deposited by high-velocity oxy-fuel spray technique on T-91 boiler tube steel. The cyclic studies were performed in a coal-fired boiler at 1123 K ± 10 K (850 °C ± 10 °C). X-ray diffraction, scanning electron microscopy/energy dispersive X-ray analysis and elemental mapping analysis techniques were used to analyze the corrosion products. All the coatings deposited on T-91 boiler tube steel imparted hot corrosion resistance. The 65 pctCr3C2 -35 pct (Ni-20Cr)-coated T-91 steel sample performed better than all other coated samples in the given environment.

  5. DMPD: CR3 (CD11b, CD18): a phagocyte and NK cell membrane receptor with multipleligand specificities and functions. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 8485905 CR3 (CD11b, CD18): a phagocyte and NK cell membrane receptor with multiplel...) (.html) (.csml) Show CR3 (CD11b, CD18): a phagocyte and NK cell membrane receptor with multipleligand spec...d NK cell membrane receptor with multipleligand specificities and functions. Authors Ross GD, Vetvicka V. Pu

  6. Effect of Cr, Ni and Mo on corrosion resistance of highly alloyed materials in sour well environments

    International Nuclear Information System (INIS)

    The effect of Cr, Ni and Mo on the corrosion behaviours of highly alloyed materials was investigated in simulated sour well environments. The increases of all of Cr, Ni and Mo contents increase the resistance to general and pitting corrosion. Increasing Ni content also improves the resistance to stress corrosion cracking (SCC). From the standpoint of those resistances, high Ni content as well as high Cr and Mo contents is essential to maintain the corrosion resistance in sour well environments. Surface film analysis shows there are two types of film structure, that is: Cr oxide single layer, and double layer with outer Ni sulfide and inner Cr oxide. Corrosion resistance is basically determined by the presence of surface Cr oxide film. Increasing Ni and Mo contents is considered to increase the stability of the surface film. In addition, electrochemical measurements were carried out with high alloy materials and pure metals to clarify the behaviours of Cr, Ni and Mo

  7. The oxidation/sulfidation behavior of Fe-Cr-Ni-Nb alloys at elevated temperatures

    International Nuclear Information System (INIS)

    Structural Fe-Cr-Ni alloys may undergo rapid degradation at elevated temperatures unless protective surface oxide scales are formed and maintained. The ability of alloys to resist rapid degradation strongly depends on their Cr content and the chemistry of the exposure environment. Normally, 20% Cr is required for service at temperatures up to 10000C, although the presence of sulfur inhibits formation of a protective surface oxide scale. The oxidation and sulfidation behavior of Fe-Cr-Ni alloys is examined with particular emphasis on the effects of alloy Cr content (12 and 25% Cr) and the addition of a reactive oxide-forming element (1-6% Nb). Niobium is shown to promote protective oxidation behavior on the 12% Cr alloy in oxidizing environments and to suppress sulfidation in mixed oxygen-sulfur-containing environments. The results for isothermal corrosion tests are presented and discussed with reference to published information

  8. 适用于Ni3Al基合金IC6的NiCoCrAlY涂层研究%NiCoCrAlY overlay coating applied to Ni3Al based alloy IC6

    Institute of Scientific and Technical Information of China (English)

    李树索; 肖程波; 宋尽霞; 韩雅芳

    2003-01-01

    为了研制适用于IC6合金的NiCoCrAlY包覆涂层,采用离子电弧镀方法在Ni3Al基合金IC6上涂覆了NiCoCrAlY 5元包覆涂层,测试了涂覆涂层后IC6合金的主要力学性能和抗氧化抗腐蚀性能.结果表明,NiCoCrAlY涂层主要由γ(Ni)、γ'(Ni3Al)、β(NiAl)和α-Cr组成,可使IC6合金的抗氧化抗腐蚀性能得到明显改善,而且对IC6合金的主要力学性能无明显影响,是IC6合金一种较为理想的防护涂层.

  9. ICP-MS Determination of Cr, Cd, Ni, Cu, Pb and Zn in Atmospheric Dust Fall%电感耦合等离子体质谱法测定大气降尘中铬、镉、镍、铜、铅和锌

    Institute of Scientific and Technical Information of China (English)

    彭萌; 诸堃; 陈莲红; 魏春蓉

    2012-01-01

    用电感耦合等离子体质谱法测定大气降尘中铬、镉、镍、铜、铅和锌等有害元素的含量。试样于敞开的聚四氟乙烯坩埚中用氢氟酸和硝酸消解,运用干扰方程校正质谱干扰。方法的测定下限(10s)在0.039-0.87μg·g-1之间。通过分析1个地质标准物质(GBW 07404)对所提出方法的准确度和精密度做了考核,所得测定结果与标准物质的认定值相吻合,各元素测定结果的相对标准偏差(n=11)均小于5.0%。%A method of ICP-MS for the determination of harmful elements, i. e. , Cr, Cd, Ni, Cu, Pb and Zn in atmospheric dust fall was proposed. Samples were digested with HF and HNO3 in an open PTFE crucible. The mass spectrometry interferences were corrected by using interference equations. Lower limits of determination (10s) found for the 6 elements were in the range of 0. 039--0. 87μg·g-1. Accuracy and precision of the proposed method were tested by analyzing a geological CRM (GBW 07404), giving results in consistency with the certified values and values of RSD's (n=11) less than 5.0%.

  10. An index to PGE-Ni-Cr deposits and occurrences in selected mineral-occurrence databases

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The data in Ni_Cr_PGE shapefile was obtained by compiling records of sites containing nickel, chromium, or one of the platinum group elements from published...

  11. Structural evolution of Ni-20Cr alloy during ball milling of elemental powders

    Energy Technology Data Exchange (ETDEWEB)

    Lopez B, I.; Trapaga M, L. G. [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Juriquilla, 76230 Queretaro (Mexico); Martinez F, E. [Centro de Investigacion e Innovacion Tecnologica, Cerrada de Cecati s/n, Col. Santa Catarina Azcapotzalco, 02250 Mexico D. F. (Mexico); Zoz, H., E-mail: israelbaez@gmail.co [Zoz GmbH, D-57482, Wenden (Germany)

    2011-07-01

    The ball milling (B M) of blended Ni and Cr elemental powders was carried out in a Simoloyer performing on high-energy scale mode at maximum production to obtain a nano structured Ni-20Cr alloy. The phase transformations and structural changes occurring during mechanical alloying were investigated by X-ray diffraction (XRD) and optical microscopy (Om). A gradual solid solubility of Cr and the subsequent formation of crystalline metastable solid solutions described in terms of the Avrami-Ero fe ev kinetics model were calculated. The XRD analysis of the structure indicates that cumulative lattice strain contributes to the driving force for solid solution between Ni and Cr during B M. Microstructure evolution has shown, additionally to the lamellar length refinement commonly observed, the folding of lamellae in the final processing stage. Om observations revealed that the lamellar spacing of Ni rich zones reaches a steady value near 500 nm and almost disappears after 30 h of milling. (Author)

  12. Improving Corrosion Resistance of Q235 Steel by Ni-Cr Alloyed Layer

    Institute of Scientific and Technical Information of China (English)

    HUANG Jun; ZHANG Pingze; WU Hongyan; BI Qiang

    2012-01-01

    Ni-Cr alloyed layer was formed on surface of Q235 steel by double glow plasma surface metallurgy to improve the corrosion resistance of substrate.The composition and microstructure of alloyed layer was analyzed by SEM and XRD.Potentiodynamic polarization and electrochemical impedance spectroscopy was applied to evaluate the corrosion resistance of the alloyed layer.The results showed working pressure had a great effect on structure of Ni-Cr alloyed layer,and the dense and smooth alloyed layer was prepared at 50 Pa working pressure.Compared with substrate,Ni-Cr alloyed layer exhibited higher corrosion potential,lower corrosion current density and larger charge transfer resistance,which indicated that Ni-Cr alloyed layer significantly modified the corrosion resistance of Q235 steel.

  13. NiCrAlY薄膜应变计的研制%Research and fabrication of NiCrAlY thin-film strain gauges

    Institute of Scientific and Technical Information of China (English)

    张洁; 杨晓东; 蒋书文; 蒋洪川; 赵晓辉; 张万里

    2015-01-01

    NiCrAlY thin film strain gauges are deposited on the nickel-based superalloy by radio-frequency magnetron sputtering. The effects of stabilized heat treatment at 1 000℃ on structure and surface morphology of NiCrAlY thin films are investigated and the electromechanical properties of NiCrAlY thin film strain gauges are measured. After stabilized heat treatment at 1 000℃,a layer of Al2 O3 is formed on the surface of NiCrAlY thin film,which is important cause for excellent high-temperature oxidation resistance. The variation of strain gauge resistance with temperature is linear in the temperature range from room temperature to 800℃. The temperature coefficient of resistance( TCR) is about 290 × 10-6/℃,and gauge factor( GF) is about 2. 1 at room temperature.%采用射频磁控溅射法在Ni基高温合金拉伸件上制备NiCrAlY薄膜应变计。研究了热稳定处理对NiCrAlY薄膜结构、表面形貌的影响,并且测试了NiCrAlY薄膜应变计的电学与应变性能。结果表明:热稳定处理后 NiCrAlY 薄膜应变计由于在表面形成了一层 Al2 O3膜,具有抗高温氧化的特性,在室温~800℃范围内,应变计电阻同温度呈线性变化,电阻温度系数( TCR)约为290×10-6/℃,室温下的应变计系数( GF)为2.1。

  14. Investigations on intercrystalline resistance of plasma arc-welded coating materials X 2 CrNiNb 19 9 and S-NiCr 20 Nb

    International Nuclear Information System (INIS)

    The resistance to intercrystalline corrosion (IC) has been tested on single and double layer plasma arc-weldings of austenite steel X2CrNiNb199 as well as the alloy inconel 82 (S-NiCr 20 Nb) using short-term testing methods. The austenite platings can be considered as IC resistant. The inconel alloy tends to selective corrosion in the potential range of -30 to +30 mVEsub(H), the areas of greater precipitation are particularly attacked. (GSCH)

  15. Heat treatment of NiCrFe alloy 600 to optimize resistance to intergranular stress corrosion

    Science.gov (United States)

    Steeves, A.F.; Bibb, A.E.

    A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprises heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cooling the alloy body, and heating the cooled body to a temperature between 1100 to 1500/sup 0/F for about 1 to 30 hours.

  16. Temperature dependence of invariant diffusion coefficient and activation energy for Fe-Cr-Ni-Co system

    International Nuclear Information System (INIS)

    Experimental determination of diffusion invariant coefficients in a four-component Fe-Cr-Ni-Co system is conducted for alloys with 16 mas.% of Cr, 13 mas.% of Ni, 2-14 mas.% of Co. Activation energies, corresponding to diffusion invariant coefficients are calculated by the least squares technique. The analysis of concentrational dependences of these coefficients has shown that under a low cobalt content the system can be characterized by the unique activation energy value

  17. High-Power Diode Laser-Treated 13Cr4Ni Stainless Steel for Hydro Turbines

    Science.gov (United States)

    Mann, B. S.

    2014-06-01

    The cast martensitic chromium nickel stainless steels such as 13Cr4Ni, 16Cr5Ni, and 17Cr4Ni PH have found wide application in hydro turbines. These steels have adequate corrosion resistance with good mechanical properties because of chromium content of more than 12%. The 13Cr4Ni stainless steel is most widely used among these steels; however, lacks silt, cavitation, and water impingement erosion resistances (SER, CER, and WIER). This article deals with characterizing 13Cr4Ni stainless steel for silt, cavitation, and water impingement erosion; and studying its improved SER, CER, and WIER behavior after high-power diode laser (HPDL) surface treatment. The WIER and CER have improved significantly after laser treatment, whereas there is a marginal improvement in SER. The main reason for improved WIER and CER is due to its increased surface hardness and formation of fine-grained microstructure after HPDL surface treatment. CER and WIER of HPDL-treated 13Cr4Ni stainless steel samples have been evaluated as per ASTM G32-2003 and ASTM G73-1978, respectively; and these were correlated with microstructure and mechanical properties such as ultimate tensile strength, modified ultimate resilience, and microhardness. The erosion damage mechanism, compared on the basis of scanning electron micrographs and mechanical properties, is discussed and reported in this article.

  18. EFFECT OF VACUUM HEAT TREATMENT ON OXIDATION BEHAVIOR OF SPUTTERED NiCrA1Y COATING

    Institute of Scientific and Technical Information of China (English)

    M.H.Li; X.F.Sun; Z.Y.Zhang; H.R.Guan; W.Y.Hu; Z.Q.Hu

    2002-01-01

    A bond coat for thermal barrier coating (TBC), NiCrAlY coating, is subjected to vac-uum heat treatment in order to remove internal stress before ceramic top coat is de-posited. The effect of vacuum heat treatment on the oxidation behavior of the sputteredNiCrAlY coating has been investigated. The as-sputtered NiCrAlY coating consists ofγ-Ni and β-NiAl phases. After vacuum heat treatment, the sputtered NiCrAlY coatingmainly consists of γ-Ni3Al, β-NiAl, γ-Ni, and trace of α-Al2O3 phases. The isother-mal oxidation of sputtered NiCrAlY coating with and without vacuum heat treatmenthas been performed at 1000C. It is shown that α-Al2O3 formed during vacuum heattreatment acts as nuclei for the formation of α-Al2O3, and the protective α-Al2O3scale is formed more rapidly on the vacuum heat treated NiCrAlY coating than thatformed on the untreated coating. Also the α-Al2O3 scale has a better adherence to thevacuum heat treated NiCrAlY coating. Therefore the vacuum heat treatment improvesthe oxidation resistance of sputtered NiCrAlY coating.

  19. Effect of Ti addition on the microstructure of NiAl-Cr(Mo) eutectic alloy%Ti含量对NiAl-Cr(Mo)共晶合金凝固组织的影响

    Institute of Scientific and Technical Information of China (English)

    肖旋; 贾玉贤; 周兰章; 郭建亭

    2008-01-01

    添加Ti降低了NiAl-Cr(Mo)共晶合金凝固过程中NiAl/Cr(Mo)共晶生长速度,导致NiAl/Cr(Mo)胞状共晶组织的粗化,并因合金偏离共晶成分而促进先共晶NiAl相的形成.在添加Ti的NiAl-Cr(Mo)共晶合金中,Ti主要分布在基体NiAl相中.随着Ti含量的提高,过饱和的NiAl(Ti)基体发生分解,促进了Ni2AlTi相的形成,并且NiAl/Cr(Mo)胞状共晶组织发生退化.Ni-33Al-28Cr-3Mo-5Ti共晶合金的NiAl基体中析出细小的Cr(Mo)相,Cr(Mo)共晶相中析出细小的NiAl相.

  20. Microstructural evidence of presence of beryllium in Ni-Cr alloys for dental prostheses; Evidencia microestrutural da presenca de berilio em ligas Ni-Cr para proteses dentarias

    Energy Technology Data Exchange (ETDEWEB)

    Alkmin, L.B.; Nunes, C.A., E-mail: lba@ppgem.eel.usp.b [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia; Coelho, G.C. [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Santos, C. [Protmat Materiais Avancados, Guaratingueta, SP (Brazil)

    2010-07-01

    This study aimed to characterize the microstructure of commercial Ni-Cr alloys for dental prosthesis, with special focus on those containing Be. For this, the materials were characterized in terms of chemical composition, phases and melting point temperature. The following techniques were used: X-ray fluorescence, ICP-OES, scanning electron microscopy, electron probe microanalysis, X-ray diffraction and differential thermal analysis. The results clearly showed the presence of a typical eutectic, formed by the Ni{sub ss} and NiBe phases in those alloys containing Be, which can be considered a 'fingerprint' of the presence of this element in these alloys. (author)

  1. Thermomechanical Processing and Roll Bonding of Tri-Layered Cu-Ni-Zn/Cu-Cr/Cu-Ni-Zn Composite

    Science.gov (United States)

    Kim, Hobyung; Kang, Gyeong Tae; Hong, Sun Ig

    2016-05-01

    Tri-layered Cu-Ni-Zn/Cu-Cr/Cu-Ni-Zn composite was processed by roll bonding and the effect of thermomechanical processing on the mechanical performance and electrical conductivity was studied. Roll-bonded composite exhibited the brief work hardening and subsequent rapid work softening because of the high stored deformation energy, leading to failure at the plastic strain of 8 to 10 pct. The mechanical instability of as-roll-bonded composites was abated by heat treatment (HT) at 723 K (450 °C) and the extended work hardening with enhanced ductility compared to that of the as-roll-bonded composites was observed after HT. The strength and electrical conductivity of clad composite is dependent on the precipitation strengthening of Cu-Cr and recovery softening of Cu-Ni-Zn during post-roll-bonding HT. The increase of roll-bonding temperature enhances the precipitation kinetics and it takes shorter time to reach maximum hardness in Cu-Cr layer during post-roll-bonding HT. The toughness of as-roll-bonded Cu-Ni-Zn/Cu-Cr/Cu-Ni-Zn clad composite at 773 K (500 °C) [42 MJ/mm3] is greater than those at 723 K (450 °C) [24 MJ/mm3] and 823 K (550 °C) [38 MJ/mm3]. The maximum toughness [100 MJ/mm3] with the electrical conductivity of 68 pct IACS was obtained in the Cu-Ni-Zn/Cu-Cr/Cu-Ni-Zn clad composite roll-bonded at 773 K (500 °C) and subsequently heat-treated at 723 K (450 °C).

  2. Ni-Cr based dental alloys; Ni release, corrosion and biological evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Reclaru, L., E-mail: lucien.reclaru@pxgroup.com [PX Holding S.A., Dep R and D Corrosion and Biocompatibility Group, Bd. des Eplatures 42, CH-2304 La Chaux-de-Fonds (Switzerland); Unger, R.E.; Kirkpatrick, C.J. [Institute for Pathology, REPAIR Lab, University Medical Center, Johannes Gutenberg University Mainz, Langenbeckstr.1, D-55101 Mainz (Germany); Susz, C.; Eschler, P.-Y.; Zuercher, M.-H. [PX Holding S.A., Dep R and D Corrosion and Biocompatibility Group, Bd. des Eplatures 42, CH-2304 La Chaux-de-Fonds (Switzerland); Antoniac, I. [Materials Science and Engineering Faculty, Politehnica of Bucharest, 060042 Bucharest (Romania); Luethy, H. [Institute of Dental Materials Science and Technology, University of Basel, Hebelstrasse 3, CH-4056 Basel (Switzerland)

    2012-08-01

    In the last years the dental alloy market has undergone dramatic changes for reasons of economy and biocompatibility. Nickel based alloys have become widely used substitute for the much more expensive precious metal alloys. In Europe the prevalence of nickel allergy is 10-15% for female adults and 1-3% for male adults. Despite the restrictions imposed by the EU for the protection of the general population in contact dermatitis, the use of Ni-Cr dental alloys is on the increase. Some questions have to be faced regarding the safety risk of nickel contained in dental alloys. We have collected based on many EU markets, 8 Ni-Cr dental alloys. Microstructure characterization, corrosion resistance (generalized, crevice and pitting) in saliva and the quantities of cations released in particular nickel and CrVI have been evaluated. We have applied non parametric classification tests (Kendall rank correlation) for all chemical results. Also cytotoxicity tests and an evaluation specific to TNF-alpha have been conducted. According to the obtained results, it was found that their behavior to corrosion was weak but that nickel release was high. The quantities of nickel released are higher than the limits imposed in the EU concerning contact with the skin or piercing. Surprisingly the biological tests did not show any cytotoxic effect on Hela and L929 cells or any change in TNF-alpha expression in monocytic cells. The alloys did not show any proinflammatory response in endothelial cells as demonstrated by the absence of ICAM-1 induction. We note therefore that there is really no direct relationship between the in vitro biological evaluation tests and the physico-chemical characterization of these dental alloys. Clinical and epidemiological studies are required to clarify these aspects. - Highlights: Black-Right-Pointing-Pointer Nickel released was higher than the limits imposed in EU in contact with the skin. Black-Right-Pointing-Pointer No direct relationship between the

  3. High-temperature oxidation studies of cold-sprayed Ni-20Cr and Ni-50Cr coatings on SAE 213-T22 boiler steel

    Science.gov (United States)

    Bala, Niraj; Singh, Harpreet; Prakash, Satya

    2009-05-01

    The high-temperature oxidation behavior of cold-sprayed Ni-20Cr and Ni-50Cr coatings on SAE 213-T22 boiler steel has been investigated at 900 °C in air under cyclic heating and cooling conditions for 50 cycles. The kinetics of oxidation of coated and bare boiler steel has been established with the help of weight change measurements. It was observed that all the coated and bare steels obeyed parabolic rate law of oxidation. X-ray diffraction, FE-SEM/EDAX and X-ray mapping techniques were used to analyse the oxidation products of the coated and uncoated boiler steel. The uncoated steel suffered corrosion in the form of intense spalling and peeling of its oxide scale, which was perhaps due to the formation of unprotective Fe 2O 3 oxide scale. Both the coatings showed better resistance to the air oxidation as compared to the uncoated steel. The Ni-50Cr coating was found to be more protective than the Ni-20Cr-coated steel. The formation of oxides and spinels of nickel and chromium may be contributing to the development of air oxidation resistance in the coatings.

  4. Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

    OpenAIRE

    Bojack, A.; Zhao, L; Morris, P. F.; Sietsma, J.

    2016-01-01

    The influence of austenitization treatment of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) on austenite formation during reheating and on the fraction of austenite retained after tempering treatment is measured and analyzed. The results show the formation of austenite in two stages. This is probably due to inhomogeneous distribution of the austenite-stabilizing elements Ni and Mn, resulting from their slow diffusion from martensite into austenite and carbide and nitride dis...

  5. Diffusional transport during the cyclic oxidation of gamma + beta, Ni-Cr-Al(Y, Zr) alloys

    Science.gov (United States)

    Nesbitt, J. A.; Heckel, R. W.

    1988-01-01

    The cyclic oxidation behavior of several cast gamma + beta, Ni-Cr-Al(Y, Zr) alloys and one low-pressure plasma spraying gamma + beta, Ni-Co-Cr-Al(Y) alloy was studied. Cyclic oxidation was found to result in a decreasing Al concentration at the oxide-metal interface due to a high rate of Al consumption coupled with oxide scale cracking and spalling. Diffusion paths plotted on the ternary phase diagram showed higher Ni concentrations with increasing cyclic oxidation exposures. The alloy with the highest rate of Al consumption and the highest Al content underwent breakaway oxidation following 500 1-hr cycles at 1200 C.

  6. Heat treatment and effects of Cr and Ni in low alloy steel

    Indian Academy of Sciences (India)

    Mohammad Abdur Razzak

    2011-12-01

    The effects of Cr and Ni on low carbon steel was observed. Undissolved carbide particles refine the austenite grain size. In the presence of nickel, chromium carbide is less effective in austenite grain refinement than chromium carbide in absence of nickel at temperature below 975°C. Nickel does not produce any austenite grain refinement but presence of nickel promotes the formation of acicular ferrites. It was also found that Ni and Cr as chromium carbide also refines the ferrite grain size and morphology. Cr as chromium carbide is more effective in refining ferrite grain size than nickel.

  7. Atomic-scale computer simulation for ternary alloy Ni-Cr-Al during early precipitation process

    Institute of Scientific and Technical Information of China (English)

    CHU Zhong; CHEN Zheng; WANG Yongxin; LU Yanli; LI Yongsheng

    2005-01-01

    The aging behaviors of Ni-Cr-Al ternary alloy are studied at temperature 873 K based on the mean-field theory, and the early precipitation process is simulated at atomic-scale with microscopic phase-field model. The precipitation mechanism of the low supersaturated alloy Ni-12.2at. % Cr-7.8at. % Al is non-classical nucleation and growth, the L12 structure (Ni3Al) and D022 structure (Ni3Cr)phases precipitate simultaneously, a part of D022 phase transmits to L12 structure phase, and other part retains its previous structure. For high supersaturated alloy, congruent ordering appears first, then followed by spinodal decomposition, the nonstoicheometric ordered phases are produced in this process, which occurs before clustering. The precipitation mechanism of Ni-8at. % Cr-18at. %Al alloy is similar to Ni-10at. % Cr-12at. %Al alloy, but the ordering process of the former is ahead of the latter.

  8. Biosorption study of Ni2+ and Cr3+ by Sargassum filipendula: kinetics and equilibrium

    Directory of Open Access Journals (Sweden)

    A. A. Seolatto

    2014-03-01

    Full Text Available In this work, the biosorption of Cr3+ and Ni2+ by Sargassum filipendula pre-treated with CaCl2 was studied. Kinetic and equilibrium experiments were carried out for mono- and multi-component solutions in a batch reactor at pH 3.0 and 30 ºC. The results from the kinetic experiments showed that Cr3+ adsorbs slower than Ni2+. This behavior was explained by means of a mechanistic analysis, which showed that Cr3+ uptake presented three adsorption stages, whereas Ni2+ adsorption presents only two. The mono-component equilibrium data, along with binary kinetic data obtained from mono-component experiments, showed that, although the kinetics for Cr3+ removal are slower, the biomass had a stronger affinity for this ion. Almost all Ni2+ is desorbed from the biomass as Cr3+ adsorbs. The binary equilibrium data also presented this behavior. The binary data was also modeled by using modified forms of the Langmuir, Jain and Snoeyink, and Langmuir-Freundlich isotherms. However, the prediction obtained presented low accuracy. An alternative modeling with artificial neural networks was presented and the results showed that this technique could be a promising tool to represent binary equilibrium data. The main contribution of this work was to obtain experimental data for Cr3+/Ni2+ adsorption, which is a system rarely found in the literature and that provides information that could be used in process modeling and simulation.

  9. Synthesis Of NiCrAlC alloys by mechanical alloying; Sintese de ligas NiCrAlC por moagem de alta energia

    Energy Technology Data Exchange (ETDEWEB)

    Silva, A.K.; Pereira, J.I.; Vurobi Junior, S.; Cintho, O.M., E-mail: alissonkws@gmail.co [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil)

    2010-07-01

    The purpose of the present paper is the synthesis of nickel alloys (NiCrAlC), which has been proposed like a economic alternative to the Stellite family Co alloys using mechanical alloying, followed by sintering heat treatment of milled material. The NiCrAlC alloys consist of a chromium carbides dispersion in a Ni{sub 3}Al intermetallic matrix, that is easily synthesized by mechanical alloying. The use of mechanical alloying enables higher carbides sizes and distribution control in the matrix during sintering. We are also investigated the compaction of the processed materials by compressibility curves. The milling products were characterized by X-ray diffraction, and the end product was featured by conventional metallography and scanning electronic microscopy (SEM), that enabled the identification of desired phases, beyond microhardness test, which has been shown comparable to alloys manufactured by fusion after heat treating. (author)

  10. The kinetics of Cr layer coated on TiNi films for hydrogen absorption

    Indian Academy of Sciences (India)

    M Singh; Vaibhav Kulsherstha; Anil Kumar; N K Acharaya; Y K Vijay

    2007-01-01

    The effect of hydrogen absorption on electrical resistance with temperature for TiNi and TiNi–Cr thin films was investigated. The TiNi thin films of thickness 800 Å were deposited at different angles ( = 0°, 30°, 45°, 60° and 75°) under 10−5 Torr pressure by thermal evaporation on the glass substrate at room temperature. A layer of Cr of thickness 100 Å was coated on the TiNi thin films. The changing rate of hydrogen absorption increases after Cr layer coating because Cr enhances the catalytic properties of hydrogen absorption in thin films. The rate of hydrogen absorption increases with temperature at lower range but at higher range of temperature it was found to decrease and also it was found that the hydrogen absorption increases with angle of deposition.

  11. NiFe epitaxial films with hcp and fcc structures prepared on bcc-Cr underlayers

    Energy Technology Data Exchange (ETDEWEB)

    Higuchi, Jumpei, E-mail: higuchi@futamoto.elect.chuo-u.ac.jp [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Ohtake, Mitsuru; Sato, Yoichi [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan); Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan)

    2011-09-30

    NiFe epitaxial films are prepared on Cr(211){sub bcc} and Cr(100){sub bcc} underlayers grown hetero-epitaxially on MgO single-crystal substrates by ultra-high vacuum rf magnetron sputtering. The film growth behavior and the crystallographic properties are studied by reflection high energy electron diffraction and pole figure X-ray diffraction. Metastable hcp-NiFe(11-bar 00) and hcp-NiFe(112-bar 0) crystals respectively nucleate on Cr(211){sub bcc} and Cr(100){sub bcc} underlayers, where the hcp-NiFe crystals are stabilized through hetero-epitaxial growth. The hcp-NiFe(11-bar 00) crystal is a single-crystal with the c-axis parallel to the substrate surface, whereas the hcp-NiFe(112-bar 0) crystal is a bi-crystal with the respective c-axes lying in plane and perpendicular each other. With increasing the film thickness, the hcp structure in the NiFe films starts to transform into more stable fcc structure by atomic displacement parallel to the hcp(0001) close packed plane. The resulting films consist of hcp and fcc crystals.

  12. Availability of heavy metals (Cd, Pb, And Cr) in agriculture from commercial fertilizers.

    Science.gov (United States)

    Nacke, H; Gonçalves, A C; Schwantes, D; Nava, I A; Strey, L; Coelho, G F

    2013-05-01

    The purpose of this study was to investigate the availability of the heavy metals cadmium (Cd), lead (Pb), and chromium (Cr) to soil and maize plants fertilized with different sources and doses of zinc (Zn) in a Rhodic Eutrudox soil. For that purpose, concentrations of Cd, Pb, and Cr were evaluated in leaf tissue and grains of maize plants and in 0-20 and 20-40 cm soil layers after fertilization with four doses of Zn from eight different sources of fertilizer. There was no accumulation of Cd, Pb, and Cr in maize grain and Cd and Cr in leaf tissue of the plants; nevertheless, there was accumulation of Pb in leaf tissue, showing its availability throughout different sources of Zn and consequent uptake by plants. Regarding the soil, it was observed that fertilizer from the different sources made Cd, Pb, and Cr available at increasing amounts proportional to increased Zn doses. Under experimental conditions, fertilization with Zn increased concentrations of heavy metals Cd, Pb and Cr in soil, further highlighting the importance of conducting more studies related to the application of mineral fertilizers for micronutrient supply and the availability of heavy metals.

  13. RECOVERY OF CADMIUM AND NICKEL FROM SCRAP Ni-Cd BATTERIES

    Institute of Scientific and Technical Information of China (English)

    J.X.Zhu; B.Yu; J.H.Li; Y.F.Nie

    2001-01-01

    Several typical methods for the recovery of Ni-Cd batteries are described in detail.Based on the comparing of hydrometallurgical and pyrometallurgical processes,the latter was selected as the suitable method for recycling Ni-Cd batteries in China.

  14. Ni-Cr alloy electrodepositing technology on Fe substrate and coating performance

    Institute of Scientific and Technical Information of China (English)

    XU Li-jian; GONG Zhu-qing; TANG Jian-xin; HE Quan-guo; HE Nong-yue; DU Jing-jing

    2007-01-01

    The Ni-Cr alloy electrodepositing technology on iron substrate in the chlorid-sulfate solution and the impacts of main processing parameters on coating composition were studied. The optimal Ni-Cr alloy electrodepositing conditions are that the cathode current density is 16 A/dm2, the plating solution temperature is 30 ℃ and the pH value is 2.5. The bright, compact coating gained under the optimal conditions has good cohesion and 24.1% Cr content. The results show that the coating is composed of crystalline, the average grain size is 82 nm and the higher the Cr content of coating, the larger the rigidity, and the higher the corrosion resistance. The rigidity of coating reaches 78.6(HR30T) and the passivation area broadens to 1.4 V when the Cr content of coating is 24.1%.

  15. CdTeO3 Deposited Mesoporous NiO Photocathode for a Solar Cell

    OpenAIRE

    Chuan Zhao; Xiaoping Zou; Sheng He

    2014-01-01

    Semiconductor sensitized NiO photocathodes have been fabricated by successive ionic layer adsorption and reaction (SILAR) method depositing CdTeO3 quantum dots onto mesoscopic NiO films. A solar cell using CdTeO3 deposited NiO mesoporous photocathode has been fabricated. It yields a photovoltage of 103.7 mV and a short-circuit current density of 0.364 mA/cm2. The incident photon to current conversion efficiency (IPCE) value is found to be 12% for the newly designed NiO/CdTeO3 solar cell. It s...

  16. Solidification morphology and microstructure properties at increased cooling rates for 18-8 Cr-Ni stainless steel

    International Nuclear Information System (INIS)

    Fe-Cr-Ni alloys are widely used, e.g. in the production of domestic appliances and in chemical processing equipment. The study presented here examines the solidification morphology and properties of the microstructure of an 18-8 CrNi steel. The influence or the cooling rate on the solidification morphology is discussed, along with quantitative descriptions of the microstructures with Cr and Ni segregations. (orig.)

  17. Fabrication and mechanical properties of AlCoNiCrFe high-entropy alloy particle reinforced Cu matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jian, E-mail: chenjian@xatu.edu.cn [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Niu, Pengyun; Wei, Ting [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Hao, Liang [College of Architecture and Civil Engineering, Xi' an University of Science and Technology, Xi' an 710054 (China); Liu, Yunzi [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Wang, Xianhui, E-mail: xhwang693@xaut.edu.cn [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Peng, Yuli [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China)

    2015-11-15

    The AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying and the AlCoNiCrFe high-entropy alloy reinforced Cu matrix composites were subsequently fabricated by powder metallurgy. The phase constituents and morphology of the alloying powders were characterized by X-ray diffractometer and scanning electron microscope, the microstructures of the Cu base composites were characterized by scanning electron microscope and transmission electron microscope, and the compression tests were made as well. The results show that the AlCoNiCrFe high-entropy alloy can form after milling for 24 h. During sintering process, no grain growth occurs and no intermetallic phases present in the AlCoNiCrFe high-entropy alloy in the Cu base composite. Compression tests show that the AlCoNiCrFe high-entropy alloy has a better strengthening effect than metallic glasses and the yield strength of the Cu matrix composite reinforced with the AlCoNiCrFe high-entropy alloy is close to the value predicted by the Voigt model based on the equal strain assumption. - Graphical abstract: AlCoNiCrFe HEA has a better strengthening effect than metallic glasses for particulate reinforced metal matrix composites. The yield strength of the Cu base composite reinforced with the AlCoNiCrFe HEA is close to the upper bound calculated by Voigt model. - Highlights: • AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying. • A novel Cu base composite reinforced with AlCoNiCrFe was fabricated. • No grain growth and no intermetallic phase present in AlCoNiCrFe during sintering. • AlCoNiCrFe has a better strengthening effect than metallic glassy in composites.

  18. The fcc-bcc crystallographic orientation relationship in AlxCoCrFeNi high-entropy alloys

    NARCIS (Netherlands)

    Rao, J. C.; Ocelik, V.; Vainchtein, D.; Tang, Z.; Liaw, P. K.; De Hosson, J. Th. M.

    2016-01-01

    This paper concentrates on the crystallographic-orientation relationship between the various phases in the Al-Co-Cr-Fe-Ni high-entropy alloys. Two types of orientation relationships of bcc phases (some with ordered B2 structures) and fcc matrix were observed in Al0.5CoCrFeNi and Al0.7CoCrFeNi alloys

  19. Microhardness of Ni-Cr alloys under different casting conditions Microdureza de ligas de Ni-Cr fundidas sob diferentes condições

    Directory of Open Access Journals (Sweden)

    José Roberto de Oliveira Bauer

    2006-03-01

    Full Text Available This study evaluated the microhardness of Ni-Cr alloys used in fixed prosthodontics after casting under different conditions. The casting conditions were: (1-flame/air torch flame made of a gas/oxygen mixture and centrifugal casting machine in a non-controlled casting environment; (2-induction/argon electromagnetic induction in an environment controlled with argon; (3-induction/vacuum electromagnetic induction in a vacuum environment; (4-induction/air electromagnetic induction in a non-controlled casting environment. The 3 alloys used were Ni-Cr-Mo-Ti, Ni-Cr-Mo-Be, and Ni-Cr-Mo-Nb. Four castings with 5 cylindrical, 15 mm-long specimens (diameter: 1.6 mm in each casting ring were prepared. After casting, the specimens were embedded in resin and polished for Vickers microhardness (VH measurements in a Shimadzu HMV-2 (1,000 g for 10 s. A total of 5 indentations were done for each ring, one in each specimen. The data was subjected to two-way ANOVA and Tukey's multiple comparison tests (alpha = 0.05. The VH values of Ni-Cr-Mo-Ti (422 ± 7.8 were statistically higher (p 0.05 and lower than the values obtained in the conditions induction/air and flame/air torch (p 0.05. The microhardness of the alloys is influenced by their composition and casting method. The hardness of the Ni-Cr alloys was higher when they were cast with the induction/air and flame/air torch methods.Este estudo avaliou a microdureza de ligas de Ni-Cr usadas em prótese fixa fundidas sob diferentes condições. As condições de fundição foram: (1-maçarico chama composta por uma mistura de gás/oxigênio e centrífuga sem o controle do ambiente de fundição; (2-indução/argônio indução eletromagnética com o ambiente controlado com argônio; (3-indução/vácuo indução eletromagnética com o ambiente sob vácuo; (4-indução/ar indução eletromagnética sem o controle da atmosfera. Foram utilizadas três ligas: Ni-Cr-Mo-Ti, Ni-Cr-Mo-Be e Ni-Cr-Mo-Nb. Foram realizadas 4

  20. Thermal evolution of vacancy-type defects in quenched FeCrNi alloys

    Science.gov (United States)

    Zhang, C. X.; Cao, X. Z.; Li, Y. H.; Jin, S. X.; Lu, E. Y.; Tian, H. W.; Zhang, P.; Wang, B. Y.

    2015-06-01

    The effect of isochronal annealing on vacancy-type defects in quenched FeCrNi alloys and SUS316 was investigated via positron annihilation technique. Vacancy-type defects clustered and grew with increasing annealing temperatures of up to 523 K and, in FeCrNi alloys, were gradually annihilated with increasing temperature. The annihilation temperature was relatively insensitive to the addition of Mo and nonmetal elements, and after annealing at 673 K, the vacancy-type defects were annihilated and dislocation-type defects were formed in all of the alloys. In addition, due to the formation of Mo-vacancy complexes, the density of defects in the Mo-diluted FeCrNi model alloy was lower than that in the FeCrNi model alloy. The long lifetime of vacancy-type defects in commercial stainless steel SUS316 was smaller than that in the FeCrNi model alloys due to the nonmetal-element-induced change in mobility of the defects. Moreover, the vacancy-type and dislocation-type defects contributed to the S and W parameters of positron annihilation during the entire annealing treatment.

  1. Separation of cadmium and nickel from waste Ni-Cd batteries

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    To separate the cadmium and nickel resources in waste Ni-Cd batteries, a self-designed vacuum distillation recycling system was studied under laboratory conditions. The effects of system temperature, operating pressure, and time on the separation of Ni and Cd were studied respectively. The mechanism of vacuum thermal recycling was also discussed. Results show that vacuum distillation is a very effective separation method for waste Ni-Cd batteries. At a constant pressure, the increase of temperature can improve the separating efficiency of Cd. When the temperature is 1 173K, cadmium can evaporate completely from the samples during 3 h at 10 Pa. The reduction of pressure in a certain range is effective to the separating of Cd from Ni-Cd batteries by vacuum distillation.

  2. Characterization of Cold-Sprayed IN625 and NiCr Coatings

    Science.gov (United States)

    Srinivasan, Dheepa; Chandrasekhar, Vighnesh; Amuthan, Ramar; Lau, Y. C.; Calla, Eklavya

    2016-04-01

    Ni-based coatings IN625® and Ni20%Cr were cold sprayed on a low-alloy steel (AISI 4130) substrate, using Helium as the process gas. Dense coatings up to 3-mm thickness were deposited, having a hardness of 500-550 HV. The coatings showed a hardness maximum, with heat treatment, before dropping to a lower value. The coating microstructure revealed two distinct types of regions, comprising grains with a high dislocation density and elongated shear bands having twins. Heat treatment led to 30-50 nm grains in the IN625 coating, and >1-2 μm grains for NiCr. Both coatings showed a compressive residual stress in the as-sprayed condition, which relaxed to a zero residual stress, at 650 °C. The NiCr coatings showed a much higher compressibility, as compared to IN625. The IN625 coatings induced a much larger deformation on the 4130 steel. Overall, while both types of Ni-based alloy coatings showed similarities in terms of hardness and microstructure, they revealed distinct differences in their deformability, thermal stability, and substrate deformation, indicating a different behavior between a binary solid solution (NiCr) as compared to a multielement solid solution (IN625), as elucidated via a detailed characterization of these coatings.

  3. Evaluation of Ni-Cr-base alloys for SOFC interconnect applications

    Science.gov (United States)

    Yang, Zhenguo; Xia, Guan-Guang; Stevenson, Jeffry W.

    To further understand the suitability of Ni-Cr-base alloys for solid oxide fuel cell (SOFC) interconnect applications, three commercial Ni-Cr-base alloys, Haynes 230, Hastelloy S and Haynes 242 were selected and evaluated for oxidation behavior under different exposure conditions, scale conductivity and thermal expansion. Haynes 230 and Hastelloy S, which have a relatively high Cr content, formed a thin scale mainly comprised of Cr 2O 3 and (Mn,Cr,Ni) 3O 4 spinels under SOFC operating conditions, demonstrating excellent oxidation resistance and a high scale electrical conductivity. In contrast, a thick double-layer scale with a NiO outer layer above a chromia-rich substrate was grown on Haynes 242 in moist air or at the air side of dual exposure samples, indicating limited oxidation resistance for the interconnect application. With a face-centered-cubic (FCC) substrate, all three alloys possess a coefficient of thermal expansion (CTE) that is higher than that of candidate ferritic stainless steels, e.g. Crofer22 APU. Among the three alloys, Haynes 242, which is heavily alloyed with W and Mo and contains a low Cr content, demonstrated the lowest average CTE at 13.1 × 10 -6 K -1 from room temperature to 800 °C, but it was also observed that the CTE behavior of Haynes 242 was very non-linear.

  4. Study of high mobility carriers in Ni-doped CdO films

    Indian Academy of Sciences (India)

    A A Dakhel

    2013-10-01

    Cadmium oxide (CdO) doped with different amounts of nickel ion thin films have been prepared on silicon and glass substrates by vacuum evaporation technique. The effects of nickel doping on the structural, electrical, optical and optoelectronic properties of the host CdO films were systematically studied. The sample elemental composition was determined by the X-ray fluorescence spectroscopy method. The X-ray diffraction method was used to study the crystalline structure of the samples. It shows that some of Ni3+ ions occupy mainly locations when in interstitial positions and Cd2+-ion vacancies of CdO lattice. The bandgap of Ni-doped CdO suffers narrowing till 10–12% compared to undoped CdO. Such bandgap narrowing was studied within the framework of the available models. The electrical behaviours show that all the prepared Ni-doped CdO films are degenerate semiconductors. However, the nickel doping influences all the optoelectrical properties of CdO. Their d.c. conductivity, carrier concentration and mobility increased compared to undoped CdO film. The largest mobility of 112.6 cm2/V.s was measured for 1–2% Ni-doped CdO film. From optoelectronics point of view, Ni-doped CdO can be used in infrared-transparent-conducting-oxide (NIR–TCO) applications.

  5. Effect of Ti Content on Solidification Structure of NiAl-Cr (Mo) Eutectic Alloy%Ti含量对NiAl-Cr(Mo)共晶合金凝固组织的影响

    Institute of Scientific and Technical Information of China (English)

    王新琴

    2014-01-01

    Taking four different contents of NiAl-Cr(Mo) alloy obtained by melting as research object,and the microstructure and micro alloy components of the alloys were analyzed by optical microscopy,electron microprobe and spectroscopy.The results show that NiAl-Cr(Mo) alloy contains only gray α-Cr(Mo) phase and the black β-NiAl phase,the content of 10% Ti element make NiAl-Cr(Mo) alloys have a certain amount of Ni2AlTi phase.%以熔炼得到4种不同含量的NiAl-Cr(Mo)合金为研究对象,通过金相显微镜、电子探针和能谱分析观察分析各合金的显微组织结构特征和微区成分.结果表明,NiAl-Cr(Mo)只包含了灰白色的α-Cr(Mo)相和黑色的β-Nial相,10%的Ti元素含量可以使NiAl-Cr(Mo)合金中产生一定量的Ni2AlTi相.

  6. Study on Dissimilar Material Welding of 12Cr2Mo1R and 06Cr19Ni10%12Cr2Mo1R与06Cr19Ni10异种材质焊接研究

    Institute of Scientific and Technical Information of China (English)

    匡清华; 毛桂军

    2015-01-01

    The welding process characteristics of 12Cr2Mo1R heat resistant steel and 06Cr19Ni10 stainless steel have been analyzed.Meanwhile, the selection procedure of argon arc welding material ER309L has been introduced. How to control the composition of alloying elements for welding seam has been stated, so as to improve the properties of welded joint.Then the feasibility of process program has been verified in the actual product eventually.%分析了12Cr2Mo1R耐热钢与06Cr19Ni10不锈钢的焊接工艺特点,介绍了氩弧焊材ER309L的选取过程,阐述了如何控制焊缝的合金元素组成,从而改善和提高焊接接头性能,并最终在实际产品中验证了工艺方案的可行性。

  7. Development of Cr{sub 3}C{sub 2}-25(Ni20Cr) nanostructured coatings; Desenvolvimento de revestimentos nanostruturados de Cr{sub 3}C{sub 2}-25(Ni20Cr)

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Cecilio Alvares da

    2012-07-01

    This study is divided in two parts. The first part is about the preparation of nanostructured Cr{sub 3}C{sub 2}-25(Ni20Cr) powders by high energy milling followed by characterization of the milled and the as received powder. Analyses of some of the data obtained were done using a theoretical approach. The second part of this study is about the preparation and characterization of coatings prepared with the nanostructured as well as the as received Cr{sub 3}C{sub 2}-25(Ni20Cr) powders. The high temperature erosion-oxidation (E-O) behavior of the coatings prepared with the two types of powders has been compared based on a technological approach. The average crystallite size of the Cr{sub 3}C{sub 2}-25(Ni20Cr) powder decreased rapidly from 145 nm to 50 nm in the initial stages of milling and thereafter decreased slowly to a steady state value of around 10 nm with further increase in milling time. This steady state corresponds to the beginning of a dynamic recovery process. The maximum lattice strain ({epsilon} = 1,17%) was observed in powders milled for 16 hours, and this powders critical crystallite size was 28 nm. In contrast, the lattice parameter attained a minimum for powders milled for 16 hours. Upon reaching the critical crystallite size, the dislocation density attained a steady state regime and all plastic deformation introduced in the material there after was in the form of events occurring at the grain boundaries, due mainly to grain boundary sliding. The deformation energy stored in the crystal lattice of the Cr{sub 3}C{sub 2}-25(Ni20Cr) powders milled for different times was determined from enthalpy variation measurements. These results indicated that the maximum enthalpy variation ({delta}H = 722 mcal) also occurred for powders milled for 16 hours. In a similar manner, the maximum specific heat variation ({delta}C{sub p} = 0,278 cal/gK) occurred for powders milled for 16 hours. The following mechanical properties of Cr{sub 3}C{sub 2}-25(Ni20Cr) coatings

  8. Microstructure of Steel 5Cr21Mn9Ni4N Alloyed by Rare Earth

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The microstructure, composition and shape of precipitated phase under as-cast and finished product state of 5Cr21Mn9Ni4N steel with different rare earth (RE) amount were studied. Mechanical properties of 5Cr21Mn9Ni4N steels withont RE addition and with RE added by 0. 2 % in mass percent were tested respectively. The results indicate that the solid solution amount of RE is about 10-6 -10-5 order of magnitude in 5Cr21Mn9Ni4N steel. Dendrite of as-cast condition is refined obviously and dimension of interstitial phase is shortened when RE is added by 0. 10%-0. 20%. But the microstructure will be coarser if surplus RE is added. Precipitated phase under finished product state distributes evenly in nearly same size with RE added by 0.2% which leads to a largely improved high temperature mechanical property.

  9. Corrosion and oxidation properties of NiCr coatings sprayed in presence of gas shroud system

    International Nuclear Information System (INIS)

    The oxidation of a NiCr bond coat during air plasma spraying was controlled by designing a gas shroud system attached to the plasma torch nozzle. Two nozzles, termed as 'normal' and 'high-speed' nozzles examined the effect of nozzle internal design on the microstructure and phase structure of coatings. X-ray diffraction and SEM morphologies showed that the shroud system reduced the oxidation of NiCr particles during the spray process. Compared with conventional air plasma spraying, the argon gas shroud reduced the coating hardness because the volume fraction of partially melted particles increased. The high-speed nozzle reduced the oxidation and hardness of NiCr coatings due to the increase of partially melted particles in the coatings.

  10. The Structure-Function Relationships of Complement Receptor Type 2 (CR2; CD21).

    Science.gov (United States)

    Hannan, Jonathan Paul

    2016-01-01

    Human complement receptor type 2 (CR2; CD21) is a surface-associated glycoprotein which binds to a variety of endogenous ligands, including the complement component C3 fragments iC3b, C3dg and C3d, the low-affinity IgE receptor CD23, and the type I cytokine, interferon-alpha. CR2 links the innate complement-mediated immune response to pathogens and foreign antigens with the adaptive immune response by binding to C3d that is covalently attached to targets, and which results in a cell signalling phenomenon that lowers the threshold for B cell activation. Variations or deletions of the CR2 gene in humans, or the Cr2 gene in mice associate with a variety of autoimmune and inflammatory conditions. A number of infectious agents including Epstein-Barr virus (EBV), Human Immunodeficiency Virus (HIV) and prions also bind to CR2 either directly or indirectly by means of C3d-targeted immune complexes. In this review we discuss the interactions that CR2 undertakes with its best characterized ligands C3d, CD23 and the EBV gp350/220 envelope protein. To date only a single physiologically relevant complex of CR2 with one of its ligands, C3d, has been elucidated. By contrast, the interactions with CD23 and EBV gp350/220, while being important from physiologic and disease-associated standpoints, respectively, are only incompletely understood. A detailed knowledge of the structure-function relationships that CR2 undergoes with its ligands is necessary to understand the implications of using recombinant CR2 in therapeutic or imaging agents, or alternatively targeting CR2 to down-regulate the antibody mediated immune response in cases of autoimmunity. PMID:26916158

  11. The Structure-Function Relationships of Complement Receptor Type 2 (CR2; CD21).

    Science.gov (United States)

    Hannan, Jonathan Paul

    2016-01-01

    Human complement receptor type 2 (CR2; CD21) is a surface-associated glycoprotein which binds to a variety of endogenous ligands, including the complement component C3 fragments iC3b, C3dg and C3d, the low-affinity IgE receptor CD23, and the type I cytokine, interferon-alpha. CR2 links the innate complement-mediated immune response to pathogens and foreign antigens with the adaptive immune response by binding to C3d that is covalently attached to targets, and which results in a cell signalling phenomenon that lowers the threshold for B cell activation. Variations or deletions of the CR2 gene in humans, or the Cr2 gene in mice associate with a variety of autoimmune and inflammatory conditions. A number of infectious agents including Epstein-Barr virus (EBV), Human Immunodeficiency Virus (HIV) and prions also bind to CR2 either directly or indirectly by means of C3d-targeted immune complexes. In this review we discuss the interactions that CR2 undertakes with its best characterized ligands C3d, CD23 and the EBV gp350/220 envelope protein. To date only a single physiologically relevant complex of CR2 with one of its ligands, C3d, has been elucidated. By contrast, the interactions with CD23 and EBV gp350/220, while being important from physiologic and disease-associated standpoints, respectively, are only incompletely understood. A detailed knowledge of the structure-function relationships that CR2 undergoes with its ligands is necessary to understand the implications of using recombinant CR2 in therapeutic or imaging agents, or alternatively targeting CR2 to down-regulate the antibody mediated immune response in cases of autoimmunity.

  12. Study on development of filler metal for Ni-Cr-W superalloy (joint research)

    International Nuclear Information System (INIS)

    Development of filler metal is the important item to be solved in study on development of Ni-Cr-W superalloy for high temperature gas-cooled reactors with coolant outlet temperatures around 1000degC. Effects of minor alloying elements on weldability were studied for the alloy with basic composition of Ni-18.5Cr-21W proposed as an optimum chemical composition for the base metal. On this basis filler metal for the Ni-Cr-W superalloy was developed. The main results obtained were as follows: (1) Minor alloying elements and condition of heat-treatment had large effects on susceptibility to cracking in the weldments of Ni-Cr-W alloy. For this reason, good weldability could not be obtained constantly using alloys within optimum range of chemical composition for the base metal. (2) Improvement effect to reduce susceptibility to cracking in the weldments was little obtained by means of increase in contents of elements which had deoxidizing or desulfurizing effect. Addition of optimum contents of Ti or Mg reduced the susceptibility to cracking in the weldments slightly. (3) It was found that elements such as Zr, Y and B, which were added to the base metal of Ni-Cr-W alloy to maintain high temperature properties, made susceptibility to cracking high significantly when accumulating basic data on weldability of this alloy. Contents of these minor alloying elements were adjusted in the lower ranges than those of the base metal. Filler metal with good weldability for Ni-Cr-W alloy was developed through the investigation of effect on weldability. (author)

  13. Effect of WIG welding on resistance to intergranular corrosion in Cr-Ni and Cr-Ni-Mo type austenitic non-stabilized steels

    International Nuclear Information System (INIS)

    The resistance to intergranular corrosion was examined for Cr-Ni and Cr-Ni-Mo austenitic steels, CSN (Czechoslovak Standard) 17240 and 17352, respectively. These steels are used for the manufacture of thick-walled parts of fast reactors. Tests showed that simulated welded joints performed by the WIG method induced no deterioration of the intergranular corrosion resistance of the steels down a 15 mm depth, provided that the time for which the heat affected zone rested within the temperature region of its formation was short enough. One-hour arrest at 650 degC was sufficient for intergranular corrosion to develop in the molybdenum-free steel; this, however, was not true of the molybdenum-containing steel. The remelting of the base material by the welding using the WIG method resulted in a slight increase in the δ-ferrite content of the weld material. No cracks were detected. (Z.M.). 1 fig., 2 tabs., 9 refs

  14. Effect of nickel concentration on the mass transfer of Fe-Ni-Cr alloys in lithium

    International Nuclear Information System (INIS)

    Corrosion and mass transfer of selected Fe-Ni-Cr alloys between 5000C and about 3000C in slowly moving lithium (approx. equal to15 mm/s) were studied in thermal-convection loops. The corrosion rates in the dissolution zones of these loops increased with the nickel concentrations of the respective alloys. All the alloys exhibited porous near-surface layers that were depleted in nickel. The greater weight loss of a 30 wt% Ni alloy relative to a 24 wt% Ni alloy could be correlated with a higher volume fraction of porosity, suggesting that the higher the starting nickel content of the alloy, the greater the volume of nickel removed from the alloy by the lithium. The results from this study indicate that higher nickel levels in Fe-Ni-Cr alloys will pose significant corrosion problems in lithium circuits operating at or above 5000C. (orig.)

  15. Cr20Ni80合金棒材闪光对焊特性%Specialities of flash butt welding of Cr20Ni80 alloy bars

    Institute of Scientific and Technical Information of China (English)

    王希靖; 蒋文学; 张昌青

    2011-01-01

    Flash butt welding of electrical heating alloy Cr20Ni80 was investigated and the mechanical properties, microstructure and hardness of the welded joints were discussed. The results showed that, on condition of selected process parameters, welding seam was good, the average joint tensile strength a-chieved 555 Mpa, elongation rate-18. 7%, cross-section reduction-20. 8%, and with no noticeable welding defects. Minimum hardness took place in the weld seams, the hardness in the heat-affected zone increased greatly. Compared with its parent material, there was no softening phenomenon. Flash butt welding of Cr20Ni80 alloy exhibited good adaptability and a welding joint with fine performance could be obtained.%对电热合金Cr20Ni80进行连续闪光对焊研究,讨论其焊接接头的力学性能、微观组织和接头硬度.结果表明:在选定的工艺参数条件下,焊缝结合良好,接头平均抗拉强度达到555 MPa,延伸率为18.7%,断面收缩率为20.8%;接头结合致密,无明显焊接缺陷;在焊缝处硬度最低,两侧的热影响区硬度明显增大,与母材相比没有出现软化现象.闪光对焊对Cr20Ni80合金的焊接具有良好的适应性,可得到性能优良的焊接接头.

  16. Transmission electron microscopy of low pressure plasma sprayed CoNiCrAlY coating

    Energy Technology Data Exchange (ETDEWEB)

    Noguchi, K.; Nishida, M.; Chiba, A. [Kumamoto Univ., Kurokami, Kumamoto (Japan)

    1996-12-01

    Plasma spray coatings are applied to steel making, aerospace, paper making and other various industrial fields. The reliability of the coating has been remarkably improved by the development of low pressure plasma spray (LPPS) technique. The present paper reports some preliminary results from a series of investigations on the microstructures in LPPS CoNiCrAlY coating, especially focuses on the difference of microstructures between the raw powder material and the resultant coating and the formation mechanism of the wavy laminated structure, since the CoNiCrAlY alloy has excellent oxidation and corrosion resistance at high temperature and is widely used in the various industrial fields mentioned above.

  17. STUDY ON Ni-Cr SYSTEM SOLAR SELECTIVE THIN FILMS PREPARED BY MAGNETRON REACTIVE SPUTTERING PROCESS

    Institute of Scientific and Technical Information of China (English)

    B.W. Wang; H. Shen

    2002-01-01

    Ni-Cr System solar selective thin solid films were prepared by d.c. magnetron reactivesputtering under the atmosphere of O2 and N2. Ni-Cr alloy was chosen as targetmaterial and copper sheets as substrate. Using SEM, Spectrophotometer and Talystepto analyze the relations between the selective characteristic and the structure, theformation and the thickness of the thin films. The aim is to obtain good solar selectivethin films with high absorptance and low emittance, which is applied to flat plate solarheat collectors.

  18. Neutron cross section covariances in the resonance region: 52Cr, 56Fe, 58Ni

    Energy Technology Data Exchange (ETDEWEB)

    Oblozinsky, P.; Cho, Y.-S.; Mattoon, C.M.; Mughabghab, S.F.

    2010-08-03

    We evaluated covariances for neutron capture and elastic scattering cross sections on major structural materials, {sup 52}Cr, {sup 56}Fe and {sup 58}Ni, in the resonance region which extends beyond 800 keV for each of them. Use was made of the recently developed covariance formalism based on kernel approximation along with data in the Atlas of Neutron Resonances. The data of most interest for AFCI applications, elastic scattering cross section uncertainties at energies above about few hundred keV, are on the level of about 12% for {sup 52}Cr, 7-8% for {sup 56}Fe and 5-6% for {sup 58}Ni.

  19. The deposition behaviour of Fe, Cr, Ni, Co and Mn in stainless steel sodium loops

    International Nuclear Information System (INIS)

    The deposition of Fe, Cr, Ni, Co and Mn as a function of temperature, oxygen level and downstream position has been studied in isothermal stainless steel loop systems at a sodium flow velocity of about 6 m/s. None of the elements show a downstream effect in deposition rate. Activation energies for deposition vary between 5 kcal/mol for Co and 33 kcal/mol for Cr. Mn is most effectively gettered by Ni. The oxygen dependent deposition behaviour reflects the corrosion behaviour of stainless steel. (orig.)

  20. Radiation effects on interface reactions of U/Fe, U/(Fe + Cr), and U/(Fe + Cr + Ni)

    Science.gov (United States)

    Shao, Lin; Chen, Di; Wei, Chaochen; Martin, Michael S.; Wang, Xuemei; Park, Youngjoo; Dein, Ed; Coffey, Kevin R.; Sohn, Yongho; Sencer, Bulent H.; Rory Kennedy, J.

    2015-01-01

    We study the effects of radiation damage on interdiffusion and intermetallic phase formation at the interfaces of U/Fe, U/(Fe + Cr), and U/(Fe + Cr + Ni) diffusion couples. Magnetron sputtering is used to deposit thin films of Fe, Fe + Cr, or Fe + Cr + Ni on U substrates to form the diffusion couples. One set of samples are thermally annealed under high vacuum at 450 °C or 550 °C for one hour. A second set of samples are annealed identically but with concurrent 3.5 MeV Fe++ ion irradiation. The Fe++ ion penetration depth is sufficient to reach the original interfaces. Rutherford backscattering spectrometry analysis with high fidelity spectral simulations is used to obtain interdiffusion profiles, which are used to examine differences in U diffusion and intermetallic phase formation at the buried interfaces. For all three diffusion systems, Fe++ ion irradiations enhance U diffusion. Furthermore, the irradiations accelerate the formation of intermetallic phases. In U/Fe couples, for example, the unirradiated samples show typical interdiffusion governed by Fick's laws, while the irradiated ones show step-like profiles influenced by Gibbs phase rules.

  1. WC-Co and Cr3C2-NiCr Coatings in Low- and High-Stress Abrasive Conditions

    Science.gov (United States)

    Kašparová, Michaela; Zahálka, František; Houdková, Šárka

    2011-03-01

    The article deals with the evaluation of abrasive wear resistance and adhesive strength of thermally sprayed coatings. The main attention was paid to differences between low- and high-stress abrasive conditions of the measuring. Conclusions include the evaluation of specific properties of the WC-Co and the Cr3C2-NiCr High Velocity Oxygen Fuel coatings and the evaluation of the changes in the behavior of the abrasive media. Mainly, the relationship between the low- and high-stress abrasion conditions and the wear mechanism in the tested materials was described. For the wear test, the abrasive media of Al2O3 and SiO2 sands were chosen. During wear tests, the volume loss of the tested materials and the surface roughness of the wear tracks were measured. The wear tracks on the tested materials and abrasive sands' morphologies were observed using Scanning Electron Microscopy. It was found that high-stress abrasive conditions change the coatings' behavior very significantly, particularly that of the Cr3C2-NiCr coating. Adhesive-cohesive properties of the coatings and relationships among individual structure particles were evaluated using tensile testing. It was found that the weak bond strength among the individual splats, structure particles, and phases plays a role in the poor wear resistance of the coatings.

  2. INFLUENCE OF ANNEALING ON HARDNESS OF Cr-Mn-Ni CAST IRONS

    Directory of Open Access Journals (Sweden)

    V. V. Netrebko

    2015-01-01

    Full Text Available The necessary level of material’s hardness is determined by the exploitation conditions and presence of technological operations during manufacturing of articles. Mechanical edge cutting machining of wear resistant materials is impeded because of their high hardness. It is recommended to apply annealing in order to decrease hardness and improve machinability. The purpose of the work consisted in obtaining of regression dependences of cast iron’s macrohardness on its chemical content after annealing at 730 °С. With the use of mathematical experimental design the regression dependences of cast iron’s macrohardness and structural components’ microhardness on С, Cr, Mn, Ni content have been established. The minimal hardness of 27,6 HRC after annealing at 730 °С is obtained in the cast iron containing: 3,9% С; 11,4% Cr; 0,6% Mn; 0,2% Ni. The maximal hardness of 70,4 HRC is obtained when the content is as follows: 1,1% С; 25,6% Cr; 5,4% Mn; 3,0% Ni. Annealing at 730 °С decreases the cast irons’ hardness containing the minimal amount of Cr, Mn and Ni. Annealing at 730 °С is recommended for cast irons alloyed by Mn and Ni for increasing of hardness.

  3. Microstructure and Fracture Toughness of FeNiCr-TiC Composite Produced by Thermite Reaction

    Science.gov (United States)

    Xi, Wenjun; Shi, Chaoliang

    The microstructures of the FeNiCr-TiC composite produced by the rapid solidification thermite process were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The effects of aging treatment on the microstructure and fracture toughness of the composite were examined. Results showed that the FeNiCr-TiC composite was composed of ferrite (α-FeNiCr), TiC and NiAl (β phase). TiC particles in the matrix were in the shape of polygon and uniformly distributed, and their size was less than 3 µm. The β phase was coherent with the ferrite matrix, and its average size was about 50 nm. The fracture toughness of composite was 22 MPa·m1/2 without aging. When the aging temperature was below 600°C, the fracture toughness of the composite had higher plateau values and reached the maximum of 32 MPa·m1/2 at aging temperature 500°C due to the precipitation of NiAl phase on the nanometer scale. The fracture toughness decreased rapidly aged at 650°C, and then kept homology value in the range of 700 to 900°C, which was attributed to the precipitation of needle-shaped carbide (Cr/Fe)7C3 at the grain boundaries.

  4. Fabrication of conventional and nanostructured NiCrC coatings via HVAF technique

    Institute of Scientific and Technical Information of China (English)

    TAO Kai; ZHANG Jie; CUI Hua; ZHOU Xiang-lin; ZHANG Ji-shan

    2008-01-01

    The conventional and nanostructured NiCrC (with chemical composition of 80%NiCr-20%CrC) coatings with high quality were fabricated via high velocity air-fuel(HVAF) spraying technique. The microstructures of these coatings were characterized by means of metallographic microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffractometry. A Vickers microhardness tester was used to determine the mechanical properties of the as-sprayed coatings. The single-line approximation(SLA) method was employed to calculate the grain size and microstrain of as-sprayed nanostructured coating based on the XRD data. The results show that nanostructured NiCrC coating possesses a more uniform and denser microstructure, much higher microhardness and better fracture toughness than its conventional counterpart. Both TEM observation and calculation results based on XRD profile show that as-sprayed nanostructured NiCrC coating has a homogeneous nanocrystalline microstructure with an average grain size of 40 nm.

  5. Electrochemical deposition and microstructural characterization of AlCrFeMnNi and AlCrCuFeMnNi high entropy alloy thin films

    Science.gov (United States)

    Soare, V.; Burada, M.; Constantin, I.; Mitrică, D.; Bădiliţă, V.; Caragea, A.; Târcolea, M.

    2015-12-01

    Al-Cr-Fe-Mn-Ni and Al-Cr-Cu-Fe-Mn-Ni high entropy alloy thin films were prepared by potentiostatic electrodeposition and the microstructure of the deposits was investigated. The thin films were co-deposited in an electrolyte based on a DMF (N,N-dimethylformamide)-CH3CN (acetonitrile) organic compound. The energy dispersive spectrometry investigation (EDS) indicated that all the five respectively six elements were successfully co-deposited. The scanning electron microscopy (SEM) analysis revealed that the film consists of compact and uniform particles with particle sizes of 500 nm to 4 μm. The X-ray diffractometry (XRD) patterns indicated that the as-deposited thin films were amorphous. Body-centered-cubic (BCC) structures were identified by XRD after the films were annealed at various temperatures under inert Ar atmosphere. The alloys adhesion on the substrate was determined by the scratch-testing method, with higher values obtained for the Al-Cr-Cu-Fe-Mn-Ni alloy.

  6. Exploring artificial layered heterostructures of LaM'O3/LaM''O3 (M'M''= NiCr, FeCr and NiV).

    Science.gov (United States)

    Liu, J.; Kareev, M.; Freeland, J. W.; Kareev, A.; Lee, H. N.; Chakhalian, J.

    2008-03-01

    Digital synthesis of atomically sharp interfaces between strongly correlated electron systems can provide a template to build completely new materials. Here we present our results on magnetism and electronic structure in LaM'O3/LaM''O3 (M'M''= NiCr, FeCr and NiV) superlattices by using polarized X-ray spectroscopies. Using laser MBE, the (111) and (100) oriented ultra-thin superlattices were grown with alternating layer thicknesses of 1 unit cell. In the bulk, LaMO3 (M=Cr,Fe,V) are antiferromagnetic insulators while LaNiO3 is a paramagnetic metal. The evolution of element specific magnetism and charge at the interface of LFO/LCO, LNO/LVO and LNO/LCO superlattices with temperature and an applied magnetic field will be discussed in detail. The superlattice results will be contrasted to the bulk magnetic properties of the constituent layers. The work has been supported by U.S. DOD-ARO under Contract No. 0402-17291.

  7. Simultaneous determination of Cr, Ni and V in urine by electrothermal atomic absorption spectrometry (ET AAS); Determinacion simultanea de Cr, Ni y V en orina mediante et aas

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, Maria A.; Hermida, Jeymi [Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of). Escuela de Quimica. Centro de Quimica Analitica

    2011-07-01

    A procedure for the simultaneous determination of Cr, Ni, and V in urine by electrothermal atomic absorption spectrometry (ET AAS) was optimized by factorial design, and performed at a pyrolysis and atomization temperatures of 1300 and 2500 deg C, respectively, using 15 {mu}g de Mg(NO{sub 3}){sub 2} as chemical modifier. Characteristics mass of 14, 6 and 220 {rho}g and detection limits of the method of 0.07, 0.38 and 0.75 {mu}g L{sup -1} were obtained for Cr, Ni and V respectively. The methodology was validated using a Liphochek Urine Metals Control sample (Bio-Rad) (P=0.05). The methodology was applied to samples of voluntary Venezuelan people, not environmentally exposed to specific emissions, and results ranging from < LOD-1.1 and 1.3-3.3 {mu}g L{sup -1} was observed for Cr and V, respectively, and not detectable levels for Ni. (author)

  8. Characterization and High-Temperature Oxidation Behavior of Cold-Sprayed Ni-20Cr and Ni-50Cr Coatings on Boiler Steels

    Science.gov (United States)

    Bala, Niraj; Singh, Harpreet; Prakash, Satya

    2011-11-01

    Microstructure and mechanical properties of cold-spray coatings are usually required in order to explore the potential industrial application of the latter. This article demonstrates the successful formulation of Ni-20Cr and Ni-50Cr coatings on two boiler steels, namely, SAE 213-T22 and SA 516 steel by cold-spray process. The microstructure, coating thickness, phase formation, and microhardness properties of the coatings were evaluated. The coatings were subjected to cyclic heating and cooling cycles at an elevated temperature of 1173.15 K (900 °C) to ascertain their high-temperature oxidation behavior. Moreover, these cyclic exposures can give useful information regarding the adhesion of the coatings with the substrate steels. Of all the coatings, the Ni-50Cr coating on SA 516 steel had a maximum average hardness value of 469 Hv. As observed from the surface field emission-scanning electron microscopy (FE-SEM) analysis, the coatings were found to have nearly dense microstructure with the sprayed particles in interlocked positions. It was concluded that the cold-spray process is suitable for spraying the preceding powders onto the given boiler steels to produce nearly dense and low oxide coatings. The coatings, in general, were found to follow the parabolic rate of oxidation and were successful in maintaining their surface contact with their respective substrate steels.

  9. Secreted aspartic protease 2 of Candida albicans inactivates factor H and the macrophage factor H-receptors CR3 (CD11b/CD18) and CR4 (CD11c/CD18).

    Science.gov (United States)

    Svoboda, Eliška; Schneider, Andrea E; Sándor, Noémi; Lermann, Ulrich; Staib, Peter; Kremlitzka, Mariann; Bajtay, Zsuzsa; Barz, Dagmar; Erdei, Anna; Józsi, Mihály

    2015-11-01

    The opportunistic pathogenic yeast Candida albicans employs several mechanisms to interfere with the human complement system. This includes the acquisition of host complement regulators, the release of molecules that scavenge complement proteins or block cellular receptors, and the secretion of proteases that inactivate complement components. Secreted aspartic protease 2 (Sap2) was previously shown to cleave C3b, C4b and C5. C. albicans also recruits the complement inhibitor factor H (FH), but yeast-bound FH can enhance the antifungal activity of human neutrophils via binding to complement receptor type 3 (CR3). In this study, we characterized FH binding to human monocyte-derived macrophages. Inhibition studies with antibodies and siRNA targeting CR3 (CD11b/CD18) and CR4 (CD11c/CD18), as well as analysis of colocalization of FH with these integrins indicated that both function as FH receptors on macrophages. Preincubation of C. albicans yeast cells with FH induced increased production of IL-1β and IL-6 in macrophages. Furthermore, FH enhanced zymosan-induced production of these cytokines. C. albicans Sap2 cleaved FH, diminishing its complement regulatory activity, and Sap2-treatment resulted in less detectable CR3 and CR4 on macrophages. These data show that FH enhances the activation of human macrophages when bound on C. albicans. However, the fungus can inactivate both FH and its receptors on macrophages by secreting Sap2, which may represent an additional means for C. albicans to evade the host innate immune system.

  10. Microstructure and mechanical properties of HVOF sprayed WC-Co/NiCrBSi, Cr{sub 3}C{sub 2} coatings on Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Oezel, Serkan [Bitlis Eren Univ. (Turkey). Dept. of Mechanical Engineering

    2013-09-01

    In this study, WC-Co/NiCrBSi and Cr{sub 3}C{sub 2} powders were coated on surface of Al alloys (AA7075-T651, AA5083, AA2024-T4) by using HVOF (High Velocity Oxy Fuel) process. The coated samples were characterized by means of a scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX, XRD), hardness and bonding strength. These results showed that the maximum hardness and minimum surface roughness have been obtained at specimens coated with WC-Co. The bonding strengths of specimens used AA2024-T4 substrates were maximum. XRD study revealed that WC, W{sub 2}C, C, Co, Cr{sub 3}Ni{sub 2}SiC, W{sub 5}Si{sub 3}, Cr{sub 7}C{sub 3}, Cr{sub 3}C{sub 2}, Cr, and Ni phases are present in the coatings. (orig.)

  11. A Study of Thin Film Resistors Prepared Using Ni-Cr-Si-Al-Ta High Entropy Alloy

    Directory of Open Access Journals (Sweden)

    Ruei-Cheng Lin

    2015-01-01

    Full Text Available Ni-Cr-Si-Al-Ta resistive thin films were prepared on glass and Al2O3 substrates by DC magnetron cosputtering from targets of Ni0.35-Cr0.25-Si0.2-Al0.2 casting alloy and Ta metal. Electrical properties and microstructures of Ni-Cr-Si-Al-Ta films under different sputtering powers and annealing temperatures were investigated. The phase evolution, microstructure, and composition of Ni-Cr-Si-Al-Ta films were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and Auger electron spectroscopy (AES. When the annealing temperature was set to 300°C, the Ni-Cr-Si-Al-Ta films with an amorphous structure were observed. When the annealing temperature was at 500°C, the Ni-Cr-Si-Al-Ta films crystallized into Al0.9Ni4.22, Cr2Ta, and Ta5Si3 phases. The Ni-Cr-Si-Al-Ta films deposited at 100 W and annealed at 300°C which exhibited the higher resistivity 2215 μΩ-cm with −10 ppm/°C of temperature coefficient of resistance (TCR.

  12. Evolution of microstructure and properties in laser cladding of a Ni-Cr-B-Si hardfacing alloy

    NARCIS (Netherlands)

    Hemmati, I.; Ocelík, V.; De Hosson, J.T.M.

    2011-01-01

    Ni-Cr-B-Si coatings are used in many industrial applications in order to improve wear and/or corrosion properties. These coatings have traditionally been deposited by thermal spray techniques but the laser cladding process is also being increasingly employed to produce Ni-Cr-B-Si coatings with super

  13. Analysis of the microstructure of Cr-Ni surface layers deposited on Fe3Al by TIG

    International Nuclear Information System (INIS)

    A series of Cr-Ni alloys were overlaid on a Fe3Al surface by tungsten inert gas arc welding (TIG) technology. The microstructure of the Cr-Ni surface layers were analysed by means of optical metallography, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicated that when the appropriate TIG parameters were used and Cr25-Ni13 and Cr25-Ni20 alloys were used for the overlaid materials, the Cr-Ni surface layers were crack-free. The matrix of the surface layer was austenite (A), pro-eutectoid ferrite (PF), acicular ferrite (AF), carbide-free bainite (CFB) and lath martensite (LM), distributed on the austenitic grain boundaries as well as inside the grains. The phase constituents of the Cr25-Ni13 surface layer were γ-Fe, Fe3Al, FeAl, NiAl, an Fe-C compound and an Fe-C-Cr compound. The microhardness of the fusion zone was lower than that of the Fe3Al base metal and Cr25-Ni13 surface layer

  14. Study on Corrosion Properties of AlCoCrFeNiCu High Entropy Alloy in Different Media%AlCoCrFeNiCu高熵合金的电化学腐蚀性能研究

    Institute of Scientific and Technical Information of China (English)

    史一功; 张铁邦; 寇宏超; 李健

    2011-01-01

    The corrosion behaviors of AlCoCrFeNiCu high entropy alloy in different media were investigated by electrochemical measurement, scanning electron microscopy (SEM) and energy dispersive spectrum (EDS). The results show that, in 3.5%NaCl and 30%HiO2 solution, lCrl8Ni9Ti stainless steel exhibits higher pitting potential and lower current density compared with AlCoCrFeNiCu high entropy alloy. The major corrosion types are pitting corrosion and localized corrosion. But in 1 mol/L H2SO4 solution, AlCoCrFeNiCu high entropy alloy exhibits much better corrosion resistance than lCrl8Ni9Ti stainless steel.%利用电化学测试、扫描电镜观察及能谱分析等方法,研究了AlCoCrFeNiCu高熵合金在不同介质中的电化学腐蚀行为.结果表明,在3.5%NaCl和30%H2O2溶液中,1Cr18Ni9Ti不锈钢与AlCoCrFeNiCu高熵合金相比,具有较正的自腐蚀电位,较小的腐蚀电流密度,AlCoCrFeNiCu高熵合金的腐蚀以点蚀和局部腐蚀为主;在1mol/L H2SO4溶液中,AlCoCrFeNiCu高熵合金的腐蚀电流密度较1Cr18Ni9Ti不锈钢小,耐腐蚀性能更好.

  15. Probing exotic magnetic phases and electrical transport in Cr-rich γ-NiFeCr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Pampa [S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Majumdar, A.K., E-mail: akm@bose.res.in [S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Ramakrishna Mission Vivekananda University, PO Belur Math, Howrah 711202 (India); Nigam, A.K. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

    2015-05-01

    We have identified ferromagnetic, antiferromagnetic, and re-entrant spin-glass-like phases in Cr-rich γ-NiFeCr alloys and studied their critical magnetic behavior. Their electrical resistivity exhibits distinct minima between 10 and 24 K with ρ∞−√T due to electron–electron interaction effects. Electron–phonon and electron–magnon contributions to ρ are isolated. The magnetoresistance shows hysteresis effects, a signature of spin-glass-like phases and a sign reversal with change of magnetic states. We have also observed that the nature of magnetic states strongly depends on the concentration of Fe and Cr. In this system, even a small amount of Fe enhances ferromagnetism a lot while addition of a little bit of Cr suppresses ferromagnetism and takes the system to the antiferromagnetic regime. The correlation between the magnetic and the electrical properties are more meaningful here since both studies were done on the same set of samples which have rather high melting points. - Highlights: • Identified ferro, antiferro, and re-entrant spin-glass phases in Ni–Fe–Cr alloys. • Resistivity ρ~−√T shows minima from 10–24 K due to electron–electron interaction. • Electron–phonon and electron–magnon contributions to ρ are isolated. • Magneto-transport measurements strengthened the magnetic phases identified. • Correlation in magnetic/electrical properties more meaningful if same samples used.

  16. Probing exotic magnetic phases and electrical transport in Cr-rich γ-NiFeCr alloys

    International Nuclear Information System (INIS)

    We have identified ferromagnetic, antiferromagnetic, and re-entrant spin-glass-like phases in Cr-rich γ-NiFeCr alloys and studied their critical magnetic behavior. Their electrical resistivity exhibits distinct minima between 10 and 24 K with ρ∞−√T due to electron–electron interaction effects. Electron–phonon and electron–magnon contributions to ρ are isolated. The magnetoresistance shows hysteresis effects, a signature of spin-glass-like phases and a sign reversal with change of magnetic states. We have also observed that the nature of magnetic states strongly depends on the concentration of Fe and Cr. In this system, even a small amount of Fe enhances ferromagnetism a lot while addition of a little bit of Cr suppresses ferromagnetism and takes the system to the antiferromagnetic regime. The correlation between the magnetic and the electrical properties are more meaningful here since both studies were done on the same set of samples which have rather high melting points. - Highlights: • Identified ferro, antiferro, and re-entrant spin-glass phases in Ni–Fe–Cr alloys. • Resistivity ρ~−√T shows minima from 10–24 K due to electron–electron interaction. • Electron–phonon and electron–magnon contributions to ρ are isolated. • Magneto-transport measurements strengthened the magnetic phases identified. • Correlation in magnetic/electrical properties more meaningful if same samples used

  17. Identification of the complement iC3b binding site in the beta 2 integrin CR3 (CD11b/CD18).

    OpenAIRE

    Ueda, T.; Rieu, P.; Brayer, J.; Arnaout, M. A.

    1994-01-01

    The divalent cation-dependent interaction of the beta 2 integrin CR3 (CD11b/CD18) with the major complement opsonic C3 fragment iC3b is an important component of the central role of CR3 in inflammation and immune clearance. In this investigation we have identified the iC3b binding site in CR3. A recombinant fragment representing the CR3 A-domain, a 200-amino acid region in the ectodomain of the CD11b subunit, bound to iC3b directly and in a divalent cation-dependent manner. The iC3b binding s...

  18. Evaluation of Ceria-Added Cr3C2-25(NiCr) Coating on Three Superalloys under Simulated Incinerator Environment

    Science.gov (United States)

    Mudgal, Deepa; Singh, Surendra; Prakash, Satya

    2015-02-01

    Cr3C2-25(NiCr) coating is widely used in wear, erosion and corrosion applications. In the present study, D-gun-sprayed Cr3C2-25(NiCr) coatings with and without 0.4 wt.% ceria incorporated were deposited on Superni 718, Superni 600 and Superco 605 substrates. Hot-corrosion runs were conducted in 40 %Na2SO4-40 %K2SO4-10 %NaCl-10 %KCl environment at 900 °C for 100 cycles. Corrosion kinetics was monitored using weight gain measurements. Characterization of corrosion products was carried out by field-emission scanning electron microscopy (FESEM)/energy-dispersive spectroscopy (EDS) and x-ray diffraction (XRD) techniques. It was observed that Cr3C2-25(NiCr) coating with and without added ceria deposited on both of the Ni-based alloys showed resistance to corrosion under the given environment. Addition of ceria enhanced the adherence of the oxide to the coating during the corrosion run and reduced the overall weight gain. However, Cr3C2-25(NiCr)-coated Superco 605 did not perform satisfactorily under this environment.

  19. Interdiffusion in Ni-rich, Ni-Cr-Al alloys at 1100 and 1200 C. I - Diffusion paths and microstructures. II - Diffusion coefficients and predicted concentration profiles

    Science.gov (United States)

    Nesbitt, J. A.; Heckel, R. W.

    1987-01-01

    Interdiffusion in Ni-rich Ni-Cr-Al alloys is investigated experimentally after annealing at 1100 and 1200 C using gamma/gamma, gamma/gamma+beta, gamma/gamma+gamma prime, and gamma/gamma+alpha diffusion couples. The amount and location of Kirkendall porosity suggests that Al diffuses more rapidly than Cr which diffuses more rapidly than Ni in the gamma phase of Ni-Cr-Al alloys. The location and extent of maxima and minima in the concentration profiles of the diffusion couples indicate that both cross-term diffusion coefficients are positive. Measurements are also presented of the ternary interdiffusion coefficients of the gamma phase in the Ni-Cr-Al system. It is shown that the interdiffusion coefficients can be accurately predicted by using a ternary finite-difference interdiffusion model.

  20. Distribution of Chemical Forms for Co,Cr,Ni and V in Typical Soils of China

    Institute of Scientific and Technical Information of China (English)

    SHAOXIAO-HOU; XINGGUANG-XI; 等

    1993-01-01

    Co,Ni,Cr and V in 25 typical soils of China were fractionated into exchangeable,carbonate bound (calcareous soils),Mn oxide bound,organically bound,amorphous Fe oxide bound,crystalline Fe oxide bound and residual forms using a seven-step sequential extraction procedure,so as to study the distribution of chemical forms of these metals as well as the effects of soil proiperties on the distribution.The results showed that most of soil Co,Ni,Cr and V were present in residual forms,and the distribution ratio averaged 48.2% for Co,53.0% for Ni,81.5% for Cr and 68.7% for V.The speciation of heavy metals was greatly influenced by soil physico-chemical properties and the chemistry of elements.The results also indicated that the recovery of metal elements by the sequential extraction procedure was satisfactory,with the relative difference between the sum of seven forms and the total content in soils averaging 9.5% for Co,12.8% for Ni,6.6% for Cr and 7.2% for V.

  1. Comparison of Clinical Effects of Au-Pt Based and Ni-Cr Based Porcelain Crowns

    Institute of Scientific and Technical Information of China (English)

    Li-chun Wu; Ye Shi; Teng Ma

    2012-01-01

    Objective To compare the long-term clinical effects of two kinds of crowns and bridges made of porcelain fused to Au-Pt alloy and Ni-Cr alloy.Methods A total of 131 teeth (64 patients) were rehabilitated using porcelain-fused-to-metal crowns,among which 59 were rehabilitated with Au-Pt alloy metal ceramic crown and 72 with Ni-Cr alloy metal ceramic crown.The porcelain fracture,shade,marginal adaptation,gingival discoloration,and gingival status after finishing restoration and 36 months of follow-up were evaluated.Results After 36 months of restoration,porcelain fused to Au-Pt alloy crown showed better clinical effects than porcelain fused to Ni-Cr alloy crown in shade,marginal adaptation,gingival discoloration,as well as gingival status (all P<0.05).Conclusion The Au-Pt alloy ceramic crown is superior to Ni-Cr alloy ceramic crown in long-term clinical effects.

  2. Chemical compatibility of uranium carbides with Cr-Fe-Ni alloys

    International Nuclear Information System (INIS)

    This paper discusses the chemical compatibility of uranium carbides and Cr-Fe-Ni alloys, which has been evaluated by thermodynamic modeling and experimental phase studies. Two reaction temperatures, 973 and 1273 K, were used to simulate normal and overtemperature operation of advanced liquid-metal fast breeder reactor fuel-cladding couples. 27 refs

  3. Cr-tolerance of the IT-SOFC La(Ni,Fe)O3 material

    NARCIS (Netherlands)

    Stodolny, M.K.

    2012-01-01

    This thesis deals with a study on the Cr-tolerance of the LaNi0.6Fe0.4O3 (LNF) material. LNF is being considered for use as a current collecting layer, an interconnect protective coating and/or an electrochemically active solid oxide fuel cell (SOFC) cathode layer in an intermediate temperature IT-S

  4. Observations on thermally cycled 20% Cr/25% Ni/Nb stabilised stainless steel

    International Nuclear Information System (INIS)

    A variety of optical and electron techniques, such as optical metallography, scanning electron microscopy and electron probe microanalysis, have been used to study the morphology and composition of oxides formed on 20 Cr/25 Ni/Nb stainless steel during oxidation at 8500C and subsequent thermal cycling in simulated reactor gas. (author)

  5. Defect and solute properties in dilute Fe-Cr-Ni austenitic alloys from first principles

    NARCIS (Netherlands)

    Klaver, T.P.C.; Hepburn, D.J.; Ackland, G.J.

    2012-01-01

    We present results of an extensive set of first-principles density functional theory calculations of point defect formation, binding, and clustering energies in austenitic Fe with dilute concentrations of Cr and Ni solutes. A large number of possible collinear magnetic structures were investigated a

  6. Large magnetocaloric effect in spinel CdCr2S4

    Science.gov (United States)

    Yan, L. Q.; Shen, J.; Li, Y. X.; Wang, F. W.; Jiang, Z. W.; Hu, F. X.; Sun, J. R.; Shen, B. G.

    2007-06-01

    Magnetocaloric effect in CdCr2S4 was investigated by magnetization and heat capacity measurements. CdCr2S4 is of a cubic spinel structure with soft ferromagnetism and performs reversible magnetic entropy in the whole experimental temperature range from 56to128K. A large magnetic entropy change ˜7.04J /kgK and adiabatic temperature change ΔTad˜2.6K are revealed for a field change of 0-5T near the Curie temperature of 87K. These results suggest that sulfospinel probably is a promising candidate as working material in magnetic refrigeration technology.

  7. RHEED study of the (1 1 0) cleavage surface of CdTe:Cr single crystals

    Science.gov (United States)

    Sagan, P.; Kuzma, M.

    2007-03-01

    The structure of (1 1 0) plane of Cr-doped CdTe single crystals has been studied by reflection high energy electron diffraction and scanning electron microscopy. Diffraction patterns consist of diffraction spots and Kikuchi lines. However, for very small incident angle, the Debye rings are observed. The constant lattice attributed to these rings is 0.8% less then for pure CdTe. These anomalous properties of the near surface layer are likely to occur due to the concentration of Cr atoms creating compressive surface strains or the effect of crystal cleavage.

  8. Interfacial microstructure and performance of brazed diamond grits with Ni-Cr-P alloy

    International Nuclear Information System (INIS)

    The reaction mechanism of the interface among diamond, commercial Ni-Cr-P alloy and steel substrate has been studied by optical microscopy, scanning electron microscope, X-ray diffraction and Raman spectroscopy. The reaction layers formed among diamond, brazing alloy and steel substrate produced good wettability of diamond grits for achieving better quality tools. The reaction layer between diamond and brazing alloy comprised a reaction layer of brazing alloy and a reaction layer of diamond. Cr7C3 and Cr3C2 formed in the reaction layer of brazing alloy was the main reason for improving the bonding strength of Ni-Cr alloy to the diamond grits. A reaction layer of diamond may be a graphitization layer formed on the surface of diamond under high temperature brazing. The reaction layer of brazing alloy and steel substrate was the co-diffusion of Ni, Cr and Fe between the brazing alloy and the steel substrate. The life and sharpness of brazed diamond boring drill bits fabricated in this study were superior to the electroplated one in the market owing to its high protrusion and bonding strength.

  9. Structural and dielectric properties of Cr-doped Ni-Zn nanoferrites

    Energy Technology Data Exchange (ETDEWEB)

    Nasir, S; Anis-ur-Rehman, M; Malik, Muhammad Ali, E-mail: marehman@comsats.edu.pk [Applied Thermal Physics Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan)

    2011-02-15

    Cr-doped Ni-Zn ferrite nanoparticles having the general formula Ni{sub 0.5}Zn{sub 0.5}Cr{sub x}Fe{sub 2-x}O{sub 4} (x=0.1, 0.3, 0.5) were prepared by the simplified sol-gel method. The structural and dielectric properties of the samples sintered at 750{+-}5 deg. C were studied. X-ray diffraction (XRD) patterns confirm the single-phase spinel structure of the prepared samples. The crystallite size calculated from the most intense peak (3 1 1) using the Debye-Scherrer formula was 29-34 nm. Scanning electron microscope images showed that the particle size of the samples lies in the nanometer regime. The dielectric constant ({epsilon}{sub r}), dielectric loss tangent (tan {delta}) and ac electrical conductivity ({sigma}{sub ac}) of nanocrystalline Cr-Ni-Zn ferrites were investigated as a function of frequency and Cr concentration. The dependence of {epsilon}{sub r}, tan {delta} and {sigma}{sub ac} on the frequency of alternating applied electric field is in accordance with the Maxwell-Wagner model. The effect of Cr doping on the dielectric and electric properties was explained on the basis of cations distribution in the crystal structure.

  10. THE SULFIDATION/OXIDATION RESISTANCE OF TWO Ni-Cr-Al-Y ALLOYS AT 700℃

    Institute of Scientific and Technical Information of China (English)

    Y.X.Lu; W.X.Chen; R.Eadie

    2004-01-01

    The high temperature corrosion resistance of Ni-25.gCr-13.5Al-1.2Y-0.6Si and Ni-10.2Co-12.4 Cr-16.0A l-0.5 Y-0.2Hf alloys was assessed in sulfidation/oxidation environments.In the environment with a sulfur partial pressure of 1Pa.and an oxygen partial pressure of 10-19Pa,both these alloys exhibited three distinct stages in the weight gain-time curve when tested at 700℃.In the initial stage,selective sulfidation of Cr suppressed the formation of the other metal sulfides,resulting in lower weight gains.In the transient stage,breakdown and cracking of Cr sulfides and insufficient concentration of Cr at the outer zone led to the rapid formation of Ni sulfides and a rapid increase in weight.In the steady-state stage,corrosion was controlled by the diffusion of anions and/or cations,which led to a parabolic rate law.

  11. Microstructure and wear resistance of laser clad Cr7 C3 reinforced Cr-Ni-Si coating%激光熔覆Cr7C3增强铬镍硅涂层组织与耐磨性

    Institute of Scientific and Technical Information of China (English)

    刁望勋; 汤海波; 方艳丽; 刘栋; 张述泉; 王华明

    2011-01-01

    A wear resistant Cr7C3 reinforced Cr-Ni-Si ternary metal silicide composite coating was fabricated on a substrate of A3 mild steel by means of laser cladding with Cr3C2 and 0. 47Cr-0. 50Ni-0. 03Si alloy powder as the precursor material. The microstructure and composition of the coating were investigated by means of optical microscopy, scanning electron microscopy, Xray diffraction, energy dispersive spectrometer and electron probe micro-analyzer. Then the wear resistance of the coating was tested under dry sliding wear condition at room temperature. Results indicated that, microhardness of the Cr-Ni-Si coating was evidently improved because of the introduction of Cr7 C3. The laser clad Cr7 C3 reinforced Cr-Ni-Si ternary metal silicide composite coating shows excellent wear resistance under dry sliding wear test conditions.%为了提高材料耐磨性,以Cr3 C2和0.47Cr-0.50Ni 0.03Si合金粉末为原料,利用激光熔覆制备工艺,在A3钢表面制得了Cr7 C3硬质相增强Cr-Ni-Si金属硅化物复合材料涂层;利用光学显微镜、扫描电子显微镜、X射线衍射仪、能谱仪与电子探针等分析了涂层的显微组织,并在室温干滑动条件下测试其耐磨性能.结果表明,硬质颗粒相Cr7 C3的加入,显著提高了Cr-Ni-Si金属硅化物涂层的硬度,涂层具有良好的室温耐磨性能.

  12. Peculiarities of directed crystallization of the Ni-Ni3Ti, Fe-Fe2Ti and NiAl-Cr eutectic alloys

    International Nuclear Information System (INIS)

    The peculiar features of the formation of two-phase structure of binary eutectics Ni-Ni3Ti, Fe-Fe2Ti and quasi-binary eutectic NiAl-Cr with the directional crystallization by the Bridgeman method are considered. It is shown that Ni-Ni3Ti eutectic is characterized by an exceptionally high sensitivity to the oriented growth. When Fe-Fe2Tiand NiAl-Cr alloys crystallize, the fan-type structure is formed. Even if specially pure starting components are used, this does not guarantee the obtaining of strictly regular structure in those alloys. The structure of directionally crystallized materials exhibits macro- and microdefects. The microdefects comprise the interrupted location and different thickness of lamellas building up clusters. The cause of their appearance resides in micrononuniformity in the composition of the melt. The macrodefects represent areas with optionally oriented lamellas that are arranged mainly at the conjunctions between three and more clusters. The form and location of the defects are stipulated by the kinetic and thermal parameters of the growth of crystals

  13. Adsorption and diffusion of fluorine on Cr-doped Ni(111) surface: Fluorine-induced initial corrosion of non-passivated Ni-based alloy

    Science.gov (United States)

    Ren, Cui-Lan; Han, Han; Gong, Wen-Bin; Wang, Cheng-Bin; Zhang, Wei; Cheng, Cheng; Huai, Ping; Zhu, Zhi-Yuan

    2016-09-01

    Adsorption and diffusion behaviors of fluorine on Cr-doped Ni(111) surface are investigated by using first-principles simulation. It shows that the Cr in the Cr-doped Ni(111) surface serve a trap site for fluorine with adsorption energy 3.52 eV, which is 1.04 eV higher than that on Ni(111) surface. Moreover, the Cr atom is pulled out the surface for 0.41 Å after the fluorine adsorption, much higher than that on Ni(111) surface. Further diffusion behaviors analysis confirms the conclusion because the fluorine diffusion from neighbored sites onto the Cr top site is an energy barrierless process. Detailed electronic structure analysis shows that a deeper hybrid state of F 2 p-Cr 3 d indicates a strong Fsbnd Cr interaction. The Nisbnd Cr bond is elongated and weakened due to the new formed Fsbnd Cr bonding. Our results help to understanding the basic fluorine-induced initial corrosion mechanism for Ni-based alloy in molten salt environment.

  14. Microstructural evolution and corrosion behavior of directionally solidified FeCoNiCrAl high entropy alloy

    Directory of Open Access Journals (Sweden)

    Cui Hongbao

    2011-08-01

    Full Text Available The FeCoNiCrAl alloys have many potential applications in the fields of structural materials, but few attempts were made to characterize the directional solidification of high entropy alloys. In the present research, the microstructure and corrosion behavior of FeCoNiCrAl high entropy alloy have been investigated under directional solidification. The results show that with increasing solidification rate, the interface morphology of the alloy evolves from planar to cellular and dendritic. The electrochemical experiment results demonstrate that the corrosion products of both non-directionally and directionally solidified FeCoNiCrAl alloys appear as rectangular blocks in phases which Cr and Fe are enriched, while Al and Ni are depleted, suggesting that Al and Ni are dissolved into the NaCl solution. Comparison of the potentiodynamic polarization behaviors between the two differently solidified FeCoNiCrAl high entropy alloys in a 3.5%NaCl solution shows that the corrosion resistance of directionally solidified FeCoNiCrAl alloy is superior to that of the non-directionally solidified FeCoNiCrAl alloy.

  15. Microstructure and Oxidation Resistance of NiCoCrAlYTa Coating by Low Pressure Plasma Spraying

    Science.gov (United States)

    Liang, X.-H.; Zhou, K. S.; Liu, M.; Hong, R. J.; Deng, C. G.; Luo, S.; Chen, Z. K.

    The NiCoCrAlYTa coating was prepared on Ni-based single crystal super-alloys by low pressure plasma spraying (LPPS). The phases and microstructures for the coatings were characterized by X-ray diffraction and scanning electron microscopy, and the fracture toughness and micro-hardness for both coatings and substrate were also investigated. The relationship between coating properties and oxidation was analyzed. The result shows that elementary distribution of NiCoCrAlYTa coatings, which consists of γ-Ni, β-NiAl, γ'-Ni3Al, and CrCoTa phases, is much homogeneous. The composition changes with depth from the surface to substrate for the coatings. The micro-hardness of coatings is 350.8 HV0.3 and fracture toughness is 2.73 MPa m1/2. The oxidation resistance of coatings excelled than Ni-based single crystal super-alloys.

  16. Testing of neutron data for Fe, Cr, Ni based on integral experiments

    International Nuclear Information System (INIS)

    In this work the modern evaluated nuclear data for structural materials such as Fe, Cr, Ni are considered, and comparison between the RUSFOND data file library and other libraries is done. Criticality calculations for a set of selected fast uranium and plutonium benchmarks are performed, and calculation results are compared with experimental data. Monte Carlo calculations were performed using continuous energy cross-sections corresponding to different data libraries. The Fe elastic scattering evaluation adopted in ENDF/B-VII.1 describe the Fe-reflected benchmarks from the ICSBEP Handbook in the best way. The reevaluation of capture cross sections of the Cr isotopes is desired. It is expected that capture properties should be effectively increased in accordance with the Mughabghab recommendations. In order to reproduce benchmark values corresponding to the HCI005 series a few increases in capture cross sections of Fe and Ni (along with Cr) are expected

  17. Phase-Specific Elastic/Plastic Interface Interactions in Layered Cr-NiAl Structures

    Energy Technology Data Exchange (ETDEWEB)

    Barabash, Rozaliya [ORNL; Liu, W. [Argonne National Laboratory (ANL); Tischler, Jonathan Zachary [ORNL; Bei, Hongbin [ORNL; Budai, John D [ORNL

    2012-01-01

    The depth-dependent, as-grown and deformation-induced strain and dislocations partitioned through the interfaces in a two-phase layered NiAl-Cr(Mo) structure are directly measured at the mesoscale using 3-D X-ray microdiffraction. It is demonstrated that in the as-grown, undeformed state, neighboring submicron Cr solid solution and NiAl eutectic lamellae (doped with {approx}3% Mo) form a heterointerface with 180{sup o} rotation around a <1 1 2> pole. It is shown that the mechanical response to the indentation of a layered composite with alternating Cr(Mo)-NiAl lamellae is distinct from the response of single-phase materials. In the center of the indent, after the load is released, the NiAl lamellae are under compressive forward stresses (with the same sign as the indentation-induced compression) while Cr solid solution lamellae are under tensile back stresses (with opposite sign from the indentation load). The depth-dependent alternation of compressive/tensile residual strains in the neighboring Cr solid solution and NiAl lamellae is understood in the framework of the Mughrabi's composite model considering two types of structure elements: harder and softer regions. Under indentation, both kinds of lamellae are assumed to deform compatibly. After the load is released, residual forward stresses are formed in the harder lamellae, and back stresses are formed in the mechanically softer lamellae. Line-broadening analysis of the intensity distribution along the diffraction vector reveals a 15-times increase in dislocation density in the near-surface zone in the center of the indent. Such a large increase is typical for severe deformation.

  18. Hypereutectoid cementite morphology and mechanical properties of Cr-Ni-Mo cast steel

    Directory of Open Access Journals (Sweden)

    E. Rożniata

    2006-04-01

    Full Text Available Purpose: The paper presents evaluation of the influence of grain normalization (refinement as a result of repeated austenitizing, cooling rate after repeated austenitizing on the morphology of hypereutectoid cementite and fracture toughness of G200CrMoNi4-6-3 cast steel. Moreover, the elimination of hypereutectoid cementite in structure of Widmannstätten type precipitates from the structure of investigated cast steel has been undertaken.Design/methodology/approach: Basic research of G200CrMoNi4-6-3 cast steel included metallographic analysis and fracture toughness research (impact strength, stress intensity factor KIc. The heat treatment has been planned on the basis of CCT diagram prepared for that cast steel.Findings: Heat treatment of investigated cast steel allows to refine the grain and eliminate from it’s structure the hypereutectoid cementite in structure of Widmannstätten type. At very low cooling rate the precipitates of hypereutectoid cementite become partially coagulated. The study of the influence of cooling rate on the mechanical properties of G200CrMoNi4-6-3 cast steel had proven that elimination of hypereutectoid cementite in structure of Widmannstätten type from the investigated cast steel structure to small degree increases it’s fracture toughness.Research limitations/implications: Research financed by the Ministry of Scientific Research and Information Technology, grant No. 3 T08B 057 29.Practical implications: G200CrMoNi4-6-3 cast steel of ledeburite class is used mainly for rolls production. Any data related to the structure and mechanical properties of that cast steel are precious for the manufacturers and users of the mill rolls.Originality/value: The new heat treatment of G200CrMoNi4-6-3 cast steel.

  19. Cr-substituted Ni-Zn ferrites via oxalate decomposition. Structural, electrical and magnetic properties

    Science.gov (United States)

    Gabal, M. A.; Al Angari, Y. M.; Al-Agel, F. A.

    2015-10-01

    A series of Cr-substituted Ni-Zn ferrites; Ni0.8Zn0.2CrxFe2-xO4 (x=0.0-1.0) were prepared via oxalate decomposition route to characterize the effect of Cr-substitution on structural, magnetic and electrical properties. The prepared powders were characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and transmission electron microscopy (TEM). XRD indicated single-phase cubic ferrites. The lattice parameters (aExp) exhibited a gradual decrease with increasing chromium, attributed to the smaller ionic radii of Cr3+ substituent. According to the obtained structural data, an appropriate cation distribution was suggested and fortified through FT-IR spectroscopy besides magnetic and electrical measurements. TEM image showed agglomerated cubic crystals with an average size of about 20 nm. Vibrating sample magnetometer (VSM) measurements indicated minimal hysteresis characteristic for soft magnetic material. The decrease in saturation magnetization (Ms) with Cr-substitution was discussed in view of Neel's two sub-lattice model. The change in the coercivity with Cr-content was discussed in view of estimated cation distribution and magnetization values. The obvious fall in the Curie temperature, estimated from molar susceptibility measurements, with increasing Cr-concentrations was assigned to the gradual replacement of Fe3+ ions on the octahedral sites by paramagnetic Cr3+ ions. ac-conductivity as a function of both frequency and absolute temperature exhibited a semi-conducting behavior. The decrease in conductivity with increasing Cr-content was attributed to the preferential occupation of Cr3+ ions by octahedral sites which replacing Fe3+ ions and limiting Fe2+-Fe3+ conduction.

  20. Preparation and Oxidation Performance of Y and Ce-Modified Cr Coating on open-cell Ni-Cr-Fe Alloy Foam by the Pack Cementation

    Science.gov (United States)

    Pang, Q.; Hu, Z. L.; Wu, G. H.

    2016-10-01

    Metallic foams with a high fraction of porosity, low density and high-energy absorption capacity are a rapidly emerging class of novel ultralight weight materials for various engineering applications. In this study, Y-Cr and Ce-Cr-coated Ni-Cr-Fe alloy foams were prepared via the pack cementation method, and the effects of Y and Ce addition on the coating microstructure and oxidation performance were analyzed in order to improve the oxidation resistance of open-cell nickel-based alloy foams. The results show that the Ce-Cr coating is relatively more uniform and has a denser distribution on the surface of the nickel-based alloy foam. The surface grains of the Ce-Cr-coated alloy foam are finer compared to those of the Y-Cr-coated alloy foam. An obvious Ce peak appears on the interface between the coating and the alloy foam strut, which gives rise to a "site-blocking" effect for the short-circuit transport of the cation in the substrate. X-ray diffraction analysis shows that the Y-Cr-coated alloy foam mainly consists of Cr, (Fe, Ni) and (Ni, Cr) phases in the surface layer. The Ce-Cr-coated alloy foam is mainly composed of Cr and (Ni, Cr) phases. Furthermore, the addition of Y and Ce clearly lead to an improvement in the oxidation resistance of the coated alloy foams in the temperature range of 900-1000 °C. The addition of Ce is especially effective in enhancing the diffusion of chromium to the oxidation front, thus, accelerating the formation of a Cr2O3 layer.

  1. MICROSTRUCTURE AND MECHANICAL PROPERTIES OF NiAl(Ti)-Cr(Mo) EUTECTIC ALLOY%NiAl(Ti)-Cr(Mo)共晶合金的微观组织和力学性能

    Institute of Scientific and Technical Information of China (English)

    肖旋; 郭建亭; 于海朋

    2006-01-01

    Ni-32Al-28Cr-3Mo-4Ti(原子分数,%)共晶合金组织由β-NiAl和α-Cr(Mo)共晶组成,并含有少量初生β-NiAl相和Ni2AlTi相.合金压缩屈服强度超过稀土Dy合金化的NiAl-Cr(Mo)合金,与NiAl-28Cr-5Mo--1Hf合金相当,表明Ti合金化有利于提高NiAl-Cr(Mo)共晶合金的强度.合金在1000℃下的蠕变断裂寿命和最小蠕变速率均与施加载荷之间呈线性的双对数关系,蠕变断裂寿命与最小蠕变速率之间满足Monkman-Grant关系修正式:tf.(·εmin)0.71=0.51.合金的室温断裂方式为共晶相的解理断裂以及NiAl与Cr(Mo)相界面的剥离,高温蠕变断裂由共晶胞界处微空洞形成和聚集所导致.

  2. Acoustic Emission Investigation of Rolling/Sliding Contact Fatigue Failure of NiCr-Cr3C2 Coating

    Science.gov (United States)

    Guolu, Li; Zhonglin, Xu; Tianshun, Dong; Haidou, Wang; Jinhai, Liu; Jiajie, Kang

    2016-08-01

    NiCr-Cr3C2 coating was fabricated using supersonic plasma spraying technology. Subsequently, rolling/sliding contact fatigue (R/SCF) testing was carried out, using acoustic emission (AE) technology to monitor the failure process. The results showed that R/SCF consists of three failure modes, namely abrasion, spalling, and delamination. Abrasion is the main failure mode, but delamination is the most severe. The AE monitoring results indicated that the R/SCF failure process is composed of normal contact, crack initiation, crack propagation, and material removal stages. The frequency of each stage was analyzed by fast Fourier transform, revealing a peak frequency for each stage mainly distributed from 200 to 250 kHz.

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

    Directory of Open Access Journals (Sweden)

    Cios G.

    2015-04-01

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

  4. Magnetic susceptibility of the frustrated spinels ZnCr2O4, MgCr2O4 and CdCr2O4

    International Nuclear Information System (INIS)

    We analyzed the magnetic susceptibilities of several Cr spinels using two recent models for the geometrically frustrated pyrochlore lattice, the Quantum Tetrahedral Mean Field model and a Generalized Constant Coupling model. Both models can describe the experimental data for ACr2O4 (with A Zn, Mg, and Cd) satisfactorily, with the former yielding a somewhat better agreement with experiment for A = Zn, Mg. The obtained exchange constants for nearest and next-nearest neighbors are discussed.

  5. High-Temperature Erosion of HVOF Sprayed Cr3C2-NiCr Coating and Mild Steel for Boiler Tubes

    Science.gov (United States)

    Yang, Guan-Jun; Li, Chang-Jiu; Zhang, Shi-Jun; Li, Cheng-Xin

    2008-12-01

    The comparison of the high-temperature erosion behavior of a High-velocity oxyfuel (HVOF) sprayed Cr3C2-NiCr coating with mild steel for circulating fluidized bed boiler tubes was investigated. Results showed that the erosion rate of the mild steel at 800 °C was four times that at 300 °C at an erosion angle of 30°. However, the erosion rate of the HVOF sprayed Cr3C2-NiCr coating was not influenced by the temperature in the range of 300-800 °C. It was found that the erosion resistance of HVOF sprayed Cr3C2-NiCr coating was more than three times higher than that of the mild steel at 700-800 °C. In addition to the ploughing on the coating surface, the cracking along splat interfaces in the coating was clearly observed on the cross-sectional microstructure. The results indicate that the erosion performance of the HVOF sprayed Cr3C2-NiCr coating is controlled by the cohesion between splats and can be further enhanced by improving splat cohesion.

  6. Biosorption kinetics of Cd (II, Cr (III and Pb (II in aqueous solutions by olive stone

    Directory of Open Access Journals (Sweden)

    M. Calero

    2009-06-01

    Full Text Available A by-product from olive oil production, olive stone, was investigated for the removal of Cd (II, Cr (III and Pb (II from aqueous solutions. The kinetics of biosorption are studied, analyzing the effect of the initial concentration of metal and temperature. Pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models have been used to represent the kinetics of the process and obtain the main kinetic parameters. The results show that the pseudo-second order model is the one that best describes the biosorption of the three metal ions for all the range of experimental conditions investigated. For the three metal ions, the maximum biosoption capacity and the initial biosorption rate increase when the initial metal concentration rises. However, the kinetic constant decreases when the initial metal concentration increases. The temperature effect on biosorption capacity for Cd (II and Cr (III is less significant; however, for Pb (II the effect of temperature is more important, especially when temperature rises from 25 to 40ºC. The biosorption capacity at mmol/g of olive stone changes in the following order: Cr>Cd>Pb. Thus, for an initial concentration of 220 mg/ℓ, a maximum sorption capacity of 0.079 mmol/g for Cr (III, 0.065 mmol/g for Cd (II and 0.028 mmol/g for Pb (II has been obtained.

  7. Corrosion behavior of a CuCrNiAl alloy in the presence of NaCl deposit

    Institute of Scientific and Technical Information of China (English)

    XU Tao; CHANG Limin; LIU Jianhua

    2006-01-01

    The corrosion behavior of a CuCrNiAl alloy with NaCl deposit at 700 and 900℃ was studied by means of metalloscope, XRD, SEM/EDX, and thermogravimetric analysis. The results indicated that the corrosion of the CuCrNiAl alloy beneath the NaCl deposit is severe; the corrosion production is loose and easy to scale off; the Cr phase is easier to erode than the Cu phase, and the contents of Cu and Cr decrease when the content of Ni increases in the matrix of the alloy beneath the corrosion region. The effects of distortion on the corrosion of the CuCrNiAl alloy were discussed, and the acceleration mechanisms of NaCl on the corrosion were also discussed.

  8. Effect of TiB2 Additives on Wear Behavior of NiCrBSi-Based Plasma-Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Oleksandr UMANSKYI

    2016-05-01

    Full Text Available The influence of titanium diboride additives on microstructure and wear-resistance of NiCrBSi thermally sprayed coatings deposited on a steel substrate has been studied. NiCrBSi-based composite powders with 10, 20, 40 wt.% TiB2 particles content were produced. The structure of NiCrSiB-TiB2 coatings consists of TiB2 and CrB grains distributed in Ni-based matrix. The wear-resistance of NiCrSiB-TiB2 plasma sprayed coatings in dry sliding conditions against the same coating using pin-on-disk tester. It was determined that the amount of titanium diboride particles in  NiCrBSi-based coatings influences essentially on the wear  resistance and wear mechanism. The NiCrBSi-based plasma sprayed coatings containing 20 wt. % of TiB2 possess the highest wear resistance due to the realization of mechano-oxidational wear mechanism.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7307

  9. Cowrie-shell architectures: Low temperature growth of Ni doped CdS film

    Energy Technology Data Exchange (ETDEWEB)

    Thool, Gautam Sheel; Sraveen, K. [Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007 (India); Singh, Ajaya Kumar [Department of Chemistry, Govt. VYT PG. Autonomous College, Durg 491001, Chhattisgarh (India); Pal, Ujjwal [Central Mechanical Engineering Research Institute, M. G. Avenue, Durgapur 713209 (India); Singh, Surya Prakash, E-mail: spsingh@iict.res.in [Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007 (India)

    2015-11-15

    In this work, we report the synthesis of Ni doped CdS cowrie-shell architectures and submicron balls like structures via low temperature chemical bath deposition method. The as-synthesized materials were systematically characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDAX), Raman spectroscopy and FTIR spectra. XRD results revealed the existence of cubic phase of CdS based material. SEM pictures depicted the growth of well define morphologies i.e. cowries-shell and submicron balls. Deposition time and dopant played significant role in the growth of CdS based different architectures. The EDAX spectra confirmed the presence of Ni into the CdS lattice. Surface structure of synthesized material was derived by FTIR analysis. - Highlights: • Ni doped CdS cowrie-shell like architectures were synthesized using low temperature aqueous solution method. • We demonstrated the deposition time and dopant played significant role in the growth of CdS based different architectures. • The formation of Ni doped CdS submicron balls has taken place by simple over growth on cowrie-shell particles. • FTIR spectra showed that the surface Cd{sup 2+} ions probably coordinated to triethanol amine molecules.

  10. Cowrie-shell architectures: Low temperature growth of Ni doped CdS film

    International Nuclear Information System (INIS)

    In this work, we report the synthesis of Ni doped CdS cowrie-shell architectures and submicron balls like structures via low temperature chemical bath deposition method. The as-synthesized materials were systematically characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDAX), Raman spectroscopy and FTIR spectra. XRD results revealed the existence of cubic phase of CdS based material. SEM pictures depicted the growth of well define morphologies i.e. cowries-shell and submicron balls. Deposition time and dopant played significant role in the growth of CdS based different architectures. The EDAX spectra confirmed the presence of Ni into the CdS lattice. Surface structure of synthesized material was derived by FTIR analysis. - Highlights: • Ni doped CdS cowrie-shell like architectures were synthesized using low temperature aqueous solution method. • We demonstrated the deposition time and dopant played significant role in the growth of CdS based different architectures. • The formation of Ni doped CdS submicron balls has taken place by simple over growth on cowrie-shell particles. • FTIR spectra showed that the surface Cd2+ ions probably coordinated to triethanol amine molecules

  11. Overaluminizing of a CoNiCrAlY Coating by Inward and Outward Diffusion Treatments

    Science.gov (United States)

    Bababdani, Samira Mohseni; Nogorani, Farhad Shahriari

    2014-04-01

    Overaluminizing is a commercially accepted treatment to enhance high temperature oxidation resistance of MCrAlY overlay coatings. In the current investigation, a low pressure plasma-sprayed CoNiCrAlY coating was aluminized by two different growth modes: outward growth and inward growth. The resultant microstructures were characterized by means of scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction analysis. The results showed that the final microstructure of both types of overaluminized coatings was similar and included Al-rich NiAl and Ni-rich NiAl zones from the top to the bottom. The details of the microstructures are discussed and compared with the results of simple aluminizing of the nickel-based substrate.

  12. Splitting phenomenon in the precipitation evolution in an Fe-Ni-Al-Ti-Cr stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Leitner, H., E-mail: Harald.Leitner@unileoben.ac.at [Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria)] [Christian Doppler Laboratory for Early Stages of Precipitation, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Schober, M. [Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Schnitzer, R. [Christian Doppler Laboratory for Early Stages of Precipitation, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria)

    2010-02-15

    The evolution of precipitation and mechanical properties of an Fe-Ni-Al-Ti-Cr stainless steel was studied during ageing at 525 deg. C. Atom probe tomography and transmission electron microscopy were applied to follow the microstructural evolution. An initial hardening reaction, which is remarkable in terms of extent, is reported to be caused by the formation of complex multi-component clusters. They are composed mainly of Ni, Al and Ti. After ageing to peak hardness (3 h), splitting of these clusters into spherical and elongated particles was observed. Based on the chemical composition, the spherical precipitates were identified to be of type NiAl B2, and the elongated particles were associated with the {eta}-phase (Ni{sub 3}(Ti, Al)). {Beta}oth types of precipitates contribute to the strength of the material.

  13. 爆炸喷涂NiCrAlTaY涂层的微观组织分析%MICROSTRUCTURE OF DS NiCrAlTaY COATING

    Institute of Scientific and Technical Information of China (English)

    张玉娟; 孙晓峰; 金涛; 韩松; 段绪海; 赵乃仁; 管恒荣; 胡壮麒

    2003-01-01

    采用爆炸喷涂工艺在单晶镍基高温合金上制备NiCrAlTaY抗氧化防护涂层.借助XRD,SEM和EDS等技术对涂层的组织结构、表面硬度与粘结强度进行分析结果显示:涂层由γ-Ni,γ′-Ni3Al,β-NiAl和喷涂过程中的氧化产物α-Al2O3组成.涂层呈典型的扁片层状结构,片层中存在柱状晶组织,层与层之间结合紧密,α-Al2O3夹在片层间涂层内的孔洞残留有空气涂层的显微硬度大,涂层/基体界面咬合紧密,结合力强.

  14. Corrosion resistance of Ni-Cr-Mo alloys. Chemical composition and metallurgical condition's effects

    International Nuclear Information System (INIS)

    Ni-Cr-Mo alloys offer an outstanding corrosion resistance in a wide variety of highly-corrosive environments. This versatility is due to the excellent performance of nickel in hot alkaline solutions and the beneficial effect of chromium and molybdenum in oxidizing and reducing conditions, respectively. Alloy C-22 (22 % Cr-13 % Mo-3% W) is a well known versatile member of this family. Due to its excellent corrosion resistance in a wide variety of environments, Alloy C-22 has been selected for the fabrication of the corrosion-resistant outer shell of the high-level nuclear waste container. The increasing demand of the industry for corrosion resistant alloys with particular properties of corrosion and mechanical resistance has led to the development of new alloys. Alloy C-22HS (Ni-21 % Cr-17 % Mo) is a new high-strength corrosion resistant material recently developed and introduced into the market. This alloy provides a corrosion resistance comparable with that of other C-type alloys, and it can also be age hardened to effectively double its yield strength. HASTELLOY HYBRID-BC1 (Ni-22 % Mo-15 % Cr) is a new development intended for filling the gap between Ni-Mo and Ni-Cr-Mo alloys. This novel alloy is able to withstand HCl and H2SO4, even in the presence of dissolved oxygen and other oxidizing species. Its resistance to chloride-induced pitting corrosion, crevice corrosion and stress corrosion cracking is also remarkable. Thermal aging of Ni-Cr-Mo alloys leads to microstructure changes depending on the temperature range and exposure time at temperature. A Long Range Ordering (LRO) reaction can occur in the range of 350 C degrees to 600 C degrees, producing an ordered Ni2(Cr,Mo) phase. This ordering reaction does not seem to affect the corrosion resistance and produces only a slight loss in ductility. LRO transformation is homogeneous and has proven to be useful to fabricate the age-hard enable Alloy C22-HS. Tetrahedral Close Packed (TCP) phases, like μ, σ and P, may

  15. Influence of Re on the Properties of a NiCoCrAlY Coating Alloy

    Institute of Scientific and Technical Information of China (English)

    J.J. Liang; H. Wei; Y.L. Zhu; X.F. Sun; Z.Q. Hu; M.S. Dargusch; X.D. Yao

    2011-01-01

    MCrAlY can serve as stand-alone overlay coatings or bond coats in thermal barrier coating systems, and its properties play a vital role in determining the performance of these coating systems. In order to further understand the behavior of MCrAlY coatings, several NiCoCrAlY model alloys with different levels of Re (0.3 wt%, 6 wt%, and 9 wt%) were investigated. Microstructural observation showed the addition of Re promoted the precipitation of Ct-rich phases, such as α-Cr and σ. The presence of α-Cr lowered the coefficient of thermal expansion (CTE) of the coating alloys, which could reduce the CTE mismatch at the scale-metal interface. The solid solution strengthening effect of Re is responsible for an increase in Rockwell hardness of the coating alloys. But the isothermal oxidation resistance at 1100℃ was deteriorated due to the precipitation of brittle α-Cr phase, a phase of inferior oxidation resistance compared with/β-NiAl and γ-Ni.

  16. Magnetic properties and structure of Ni80Fe20/Ni48Fe12Cr40 bilayer films deposited on SiO2/Si(100) by electron beam evaporation

    Institute of Scientific and Technical Information of China (English)

    WU Ping; GAO Yanqing; QIU Hong; PAN Liqing; TIAN Yue; Wang Fengping

    2007-01-01

    Ni80Fe20/Ni48Fe12Cr40 bilayer films and Ni80Fe20 monolayer films were deposited at room temperature on SiO2/Si(100) substrates by electron beam evaporation. The influence of the thickness of the Ni48Fe12Cr40underlayer on the structure, magnetization, and magnetoresistance of the Ni80Fe20/Ni48Fe12Cr40 bilayer film was investigated. The thickness of the Ni48Fe12Cr40 layer varied from about 1 nm to 18 nm while the Ni80Fe20 layer thickness was fixed at 45 nm. For the as-deposited bilayer films the introducing of the Ni48Fe12Cr40 underlayer promotes both the (111) texture and grain growth in the Ni80Fe20 layer. The Ni48Fe12Cr40 underlayer has no significant influence on the magnetic moment of the Ni80Fe20/Ni48Fe12Cr40 bilayer film. However, the coercivity of the bilayer film changes with the thickness of the Ni48Fe12Cr40underlayer. The optimum thickness of the Ni48Fe12Cr40 underlayer for improving the anisotropic magnetoresistance effect of the Ni80Fe20/Ni48Fe12Cr40 bilayer film is about 5 nm. With a decrease in temperature from 300 K to 81 K, the anisotropic magnetoresistance ratio of the Ni80Fe20 (45 nm)/Ni48Fe12Cr40 (5 nm) bilayer film increases linearly from 2.1% to 4.8% compared with that of the Ni80Fe20 monolayer film from 1.7% to 4.0%.

  17. Determination of As, Cd, Cr, Cu, Hg, Sb and Se concentrations by radiochemical neutron activation analysis in different Brazilian regional diets

    International Nuclear Information System (INIS)

    Radiochemical separation procedures developed for the determination of seven elements: As, Cd, Cr, Cu, Hg, Sb and Se in different Brazilian regional diets are described. In the case of the elements As, Hg, Sb and Se, the procedure was based on retention in inorganic exchanger TFO (tin dioxide) and determination of Hg by extraction with Ni(DDC)2. For determination of Cd, Cr, Cu and Se the procedure chosen was based on retention in inorganic exchanger HMD (hydrated manganese dioxide) and extraction of Cu and Cd as diethyldithiocarbamate compounds. The accuracy and precision of the methods studied were tested by means of analyses of different reference materials-Due to the lack of data on trace element levels in Brazilian foodstuffs and diets, these methods were applied to determination of these elements in different Brazilian regional diets. These s were supplied by the Food and Experimental Nutrition Department of the Faculty of Pharmaceutical Science, University of Sao Paulo. The daily intake values for these diets are presented for As, Cd, Cr, Cu, Hg, Sb and Se. (author) 21 refs.; 6 tabs

  18. Tensile and impact behaviour of sinter-forged Cr, Ni and Mo alloyed powder metallurgy steels

    International Nuclear Information System (INIS)

    Sintered and forged low-alloy P/M steels containing Cr, Ni and Mo were subjected to tensile, hardness and impact tests, in order to understand the influence of the alloying elements and microstructure on their mechanical properties. Elemental powders of atomized iron, graphite, chromium, nickel and molybdenum were mixed in suitable proportions using a ball mill, compacted and sintered in order to yield the following alloy compositions: Fe-0.2%C, Fe-0.2%C-1%Cr, Fe-0.2%C-1%Cr-2%Ni, Fe-0.2%C-2%Ni and Fe-0.2%C-2%Ni-1.5%Mo. Cylindrical compacts of 24 mm diameter and 32 mm height were prepared from the powder mixes in a 1000 kN hydraulic press using suitable cylindrical die-punch combination. Sintering of the ceramic-coated cylindrical preforms was carried out at 1000 ± 10 oC in a muffle furnace for a period of 120 min. Immediately after sintering, the cylindrical compacts were hot upset forged and drawn into square cross-section bars of density values to near-theoretical using a 2000 kN friction screw press. The size of the bars was maintained as 10 x 10 x 110 mm for preparing tensile specimen and 12 x 12 x 70 mm for impact specimen. Standard tensile and impact specimens were machined off from the forged square rods. Standard procedure was followed for conducting tensile test and impact test on the forged alloys. Hardness of the hot forged alloys was also measured using Rockwell hardness tester. Microstructures of the alloys were examined for correlating with the mechanical properties. Fractographs of the fractured surfaces of the tensile specimens were obtained using a scanning electron microscope. From the present study, it is contended that the alloying elements Cr, Ni and Mo have strong influence on the tensile and impact properties of the low-alloy steels studied. Among all the five alloys considered, the steel with chromium addition has exhibited the highest tensile strength with the corresponding impact strength being the least. The same alloy has also been

  19. Complement receptors type 1 (CR1, CD35) and 2 (CR2, CD21) cooperate in the binding of hydrolyzed complement factor 3 (C3i) to human B lymphocytes

    DEFF Research Database (Denmark)

    Leslie, Robert Graham Quinton; Prodinger, Wolfgang Maria; Nielsen, Claus Henrik

    2003-01-01

    The C3b-binding receptor, CR1/CD35, supports CR2/CD21-mediated activation of complement by human B lymphocytes, possibly by associating with CR2 to promote or stabilize the binding of hydrolyzed C3 (C3i), the primary component of the AP convertase, C3i-Bb. To evaluate this hypothesis, we examined...... the uptake kinetics and binding equilibria for C3i dimer interaction with human blood cells in the absence and presence of CR1- and CR2-blocking mAb. C3i displayed dual uptake kinetics to B lymphocytes, comprising of rapid binding to CR1 and slower binding to CR2. The forward rate constants (k(1)) for CR1...

  20. EFFECT OF Re ON THE HOT-CORROSION BEHAVIOR OF A NiCrAlY OVERLAY COATING%Re对NiCrAlY涂层热腐蚀行为的影响

    Institute of Scientific and Technical Information of China (English)

    韦华; 黄粮; 梁静静; 孙晓峰; 管恒荣; 胡壮麒

    2010-01-01

    通过电弧离子镀制备了NiCrAlYRe和NiCrAlY涂层,经真空热处理后涂层均由γ'-Ni3Al、γ-Ni、β-NiAl和α-Cr四相构成.在NiCrAlYRe涂层中,Re主要存在于α-Cr相,Re促进了α-Cr相在涂层中的析出,并提高了α-Cr在长期氧化过程中的稳定性,特别在氧化膜/涂层界面上析出了大量富Re的α-Cr.由于富Re的α-Cr同α-Al2O3具有极为接近的热膨胀系数,降低了氧化膜中的热应力,提高了NiCrAlY涂层表面抗剥落能力.添加Re明显提高了NiCrAlY涂层在900℃90%Na2SO4+10%K2SO4介质中的抗热腐蚀性能.

  1. Microstructure and Abrasive Wear Resistance of 18Cr-4Ni-2.5Mo Cast Steel

    Directory of Open Access Journals (Sweden)

    B. Kalandyk

    2012-12-01

    Full Text Available An influence of a decreased Cr content on the microstructure of the highly alloyed Cr-Ni cast steel, duplex type, melted under laboratoryconditions, was characterized in the paper. The microstructure investigations were performed in the initial state and after the heat treatment (solution annealing at 1060C as well as the phase transformation kinetics at continuous cooling was measured. The wear resistance of the investigated cast steel was tested and compared with the 24%Cr-5%Ni-2.5%Mo cast steel.The Cr content decrease, in ferritic-austenitic cast steels (duplex, from 24-26%Cr to 18% leads to the changes of the castingsmicrostructure and eliminating of a brittle  phase. In dependence of the casting cooling rate, apart from ferrite and austenite, also fine martensite precipitates occur in the casting structure. It was shown that the investigated cast steel is characterised by a slightly lower wear resistance than the typical cast steel duplex grades.

  2. Dephosphorization of stainless steel and high Cr-high Ni-high Mo alloys

    International Nuclear Information System (INIS)

    Investigation was carried out about dephosphorization by both oxidizing and reducing of 10-20%Cr metals using several kinds of flux, such as Na2CO3-NaCl, K2CO3-KCl, CaO-CaF2, BaO-BaCl2, CaC2-CaF2 and CaCN2-CaF2. It was recognized that CaC2-20%CaF2 flux was adequate to dephosphorization of high Cr content molten metal, because higher Cr content was advantageous for dephosphorization and high degree of dephosphorization was obtained. Experiments of dephosphorization was carried out with CaC2-20% CaF2 flux and it was applied to high Cr, high Ni, high Mo commercial alloys. The results are summerrized as follows: 1) S, N and O contents in addition to P of the molten metals reduced after flux addition, and carbon increased. 2) The effects of alloying elements on dephosphorization are that Cr is advantageous, Ni is disadvantageous, and Mo, Si, Mn have little influence. 3) Because of rephosphorization, the slag after dephosphorization should be completely cut off. 4) The stink of the slag after dephosphorization can be extinguished by wasted nitricacid treatment. (author)

  3. Precipitation kinetics in austenitic 18Cr-30Ni-Nb cast steel

    OpenAIRE

    M. Garbiak; R. Chylińska

    2008-01-01

    The study presents the results of investigations on the precipitation kinetics in austenitic 18%Cr-30%Ni cast steel stabilised with an addition of 1.84 wt% niobium. Phase analysis of isolates extracted from the alloy subjected to annealing within the temperature range of 600–1000oC during 10–1000 h was made. The phase constitution of the isolates mainly comprised niobium carbides of the NbC type and complex chromium carbides of the Cr23C6 type. In specimens annealed within the temperature ran...

  4. Study on Composite Coating of Cr23C6, CrB/Ni3Al/γ-Ni Prepared by Laser Cladding%Cr23C6,CrB/Ni3Al/γ-Ni激光复合涂层研究

    Institute of Scientific and Technical Information of China (English)

    程广萍; 毕蓉蓉

    2011-01-01

    在低碳钢基底表面激光熔覆Ni60AAA与镍包铝的混合粉,利用扫描电镜、能谱仪以及X射线衍射等分析手段对涂层组织结构进行了分析.结果表明,涂层主要包含γ-Ni、NiAl、CrC和CrB相,其中先共晶γ-Ni为主要基体相,呈树枝晶形貌,NiAl相也呈树枝晶形貌,游离、均匀分布于涂层;共晶体呈网状分布于两种树枝晶的晶界上;适当提高熔覆功率可以改善涂层的成形性及表面质量,在2.2 kW功率下,Ni60AAA与镍包铝激光合金涂层完整、致密,涂层与基体实现了完全冶金结合.%Composite coating were prepared on mild steel substrate by laser cladding with mixed powder of nickel-base alloy and Ni-coated Al. The microstructure and phase constitution of the coating was studied through SEM, EDX and X-ray diffraction analysis technique. The results show that the composite coating consists of γ-Ni, Ni3Al, Cr23C6 and CrB, with the main matrix γ-Ni solid solution being dendrite and the phase of Ni3Al also being free uniformity dendrite, both of the dendrites surrounded continuously by the eutectic. The formability and surface quality of the composite coating are improved when appropriately increasing the power. Compact and complete coats jointed metallurgically with the steel are obtained on 2.2 kW powers.

  5. CdTe polycrystalline films on Ni foil substrates by screen printing and their photoelectric performance

    International Nuclear Information System (INIS)

    Highlights: • The sintered CdTe polycrystalline films by a simple screen printing. • The flexible Ni foil was chose as substrates to reduce the weight of the electrode. • The compact CdTe film was obtained at 550 °C sintering temperature. • The photoelectric activity of the CdTe polycrystalline films was excellent. - Abstract: CdTe polycrystalline films were prepared on flexible Ni foil substrates by sequential screen printing and sintering in a nitrogen atmosphere for the first time. The effect of temperature on the quality of the screen-printed film was investigated in our work. The high-quality CdTe films were obtained after sintering at 550 °C for 2 h. The properties of the sintered CdTe films were characterized by scanning electron microscopy, X-ray diffraction pattern and UV–visible spectroscopy. The high-quality CdTe films have the photocurrent was 2.04 mA/cm2, which is higher than that of samples prepared at other temperatures. Furthermore, CdCl2 treatment reduced the band gap of the CdTe film due to the larger grain size. The photocurrent of photoelectrode based on high crystalline CdTe polycrystalline films after CdCl2 treatment improved to 2.97 mA/cm2, indicating a potential application in photovoltaic devices

  6. CdTe polycrystalline films on Ni foil substrates by screen printing and their photoelectric performance

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Huizhen [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Ma, Jinwen [College of New Energy, Bohai University, Jinzhou, Liaoning 121013 (China); Mu, Yannan [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Department of Physics and Chemistry, Heihe University, Heihe 164300 (China); Su, Shi; Lv, Pin; Zhang, Xiaoling; Zhou, Liying; Li, Xue; Liu, Li; Fu, Wuyou [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Yang, Haibin, E-mail: yanghb@jlu.edu.cn [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China)

    2015-06-15

    Highlights: • The sintered CdTe polycrystalline films by a simple screen printing. • The flexible Ni foil was chose as substrates to reduce the weight of the electrode. • The compact CdTe film was obtained at 550 °C sintering temperature. • The photoelectric activity of the CdTe polycrystalline films was excellent. - Abstract: CdTe polycrystalline films were prepared on flexible Ni foil substrates by sequential screen printing and sintering in a nitrogen atmosphere for the first time. The effect of temperature on the quality of the screen-printed film was investigated in our work. The high-quality CdTe films were obtained after sintering at 550 °C for 2 h. The properties of the sintered CdTe films were characterized by scanning electron microscopy, X-ray diffraction pattern and UV–visible spectroscopy. The high-quality CdTe films have the photocurrent was 2.04 mA/cm{sup 2}, which is higher than that of samples prepared at other temperatures. Furthermore, CdCl{sub 2} treatment reduced the band gap of the CdTe film due to the larger grain size. The photocurrent of photoelectrode based on high crystalline CdTe polycrystalline films after CdCl{sub 2} treatment improved to 2.97 mA/cm{sup 2}, indicating a potential application in photovoltaic devices.

  7. Effect of Cr on Microstructure and Properties of a Series of AlTiCr x FeCoNiCu High-Entropy Alloys

    Science.gov (United States)

    Li, Anmin; Ma, Ding; Zheng, Qifeng

    2014-04-01

    A series of AlTiCr x FeCoNiCu ( x: molar ratio, x = 0.5, 1.0, 1.5, 2.0, 2.5) high-entropy alloys (HEAs) were prepared by vacuum arc furnace. These alloys consist of α-phase, β-phase, and γ-phase. These phases are solid solutions. The structure of α-phase and γ-phase is face-centered cubic structure and that of β-phase is body-centered cubic (BCC) structure. There are four typical cast organizations in these alloys such as petal organization (α-phase), chrysanthemum organization (α-phase + β-phase), dendrite (β-phase), and inter-dendrite (γ-phase). The solidification mode of these alloys is affected by Chromium. If γ-phase is not considered, AlTiCr0.5FeCoNiCu and AlTiCrFeCoNiCu belong to hypoeutectic alloys; AlTiCr1.5FeCoNiCu, AlTiCr2.0FeCoNiCu, and AlTiCr2.5FeCoNiCu belong to hypereutectic alloys. The cast organizations of these alloys consist of pro-eutectic phase and eutectic structure (α + β). Compact eutectic structure and a certain amount of fine β-phase with uniform distribution are useful to improve the microhardness of the HEAs. More γ-phase and the microstructure with similar volume ratio values of α-phase and β-phase improve the compressive strength and toughness of these alloys. The compressive fracture of the series of AlTiCr x FeCoNiCu HEAs shows brittle characteristics, suggesting that these HEAs are brittle materials.

  8. Study of fatigue and fracture behavior of NbCr{sub 2}-based alloys: Phase stability in Nb-Cr-Ni ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J.H.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-12-01

    Phase stability in a ternary Nb-Cr-Ni Laves phase system was studied in this paper. Their previous study in NbCr{sub 2}-based transition-metal Laves phases has shown that the average electron concentration factor, e/a, is the dominating factor in controlling the phase stability of NbCr{sub 2}-based Laves phases when the atomic size ratios are kept identical. Since Ni has ten out-shell electrons, the substitution of Ni for Cr in NbCr{sub 2} will increase the average electron concentration of the alloy, thus leading to the change of the crystal structures from C15 to C14. In this paper, a number of pseudo-binary Nb(Cr,Ni){sub 2} alloys were prepared, and the crystal structures of the alloys after a long heat-treatment at 1000 C as a function of the Ni content were determined by the X-ray diffraction technique. The boundaries of the C15/C14 transition were determined and compared to their previous predictions. It was found that the electron concentration and phase stability correlation is obeyed in the Nb-Cr-Ni system. However, the e/a ratio corresponding to the C15/C14 phase transition was found to move to a higher value than the predicted one. The changes in the lattice constant, Vickers hardness and fracture toughness were also determined as a function of the Ni content, which were discussed in light of the phase stability difference of the alloys.

  9. Influences of doping Cr/Fe/Ta on the performance of Ni/CeO2 catalyst under microwave irradiation in dry reforming of CH4

    Science.gov (United States)

    Odedairo, Taiwo; Ma, Jun; Chen, Jiuling; Wang, Shaobin; Zhu, Zhonghua

    2016-01-01

    The structure of Ni/CeO2 catalyst with doping of Cr, Fe and Ta was investigated with XRD, N2 physisorption, XPS and HRTEM and the catalytic activity of the catalysts under microwave irradiation in dry reforming of methane was tested in a microwave reactor. The results show that the introduction of Cr and Ta to Ni/CeO2 can enhance the interaction between Ni and the support/promoter and inhibit the enlargement of NiO particles during the synthesis. The CH4 conversions in dry reforming on the catalysts follow the order: Ni/CeO2<2Fe-Ni<2Ta-Ni<2Cr-Ni. The superior performance of 2Ta-Ni and 2Cr-Ni may be attributed to the locally-heated Ni particles caused by the strong microwave absorption of the in-situ grown graphene attached on them under microwave irradiation.

  10. Study of Oxidation Behaviour of Bond Coating Nanocomposites Ni-20Cr-6Al Powder Synthesized by Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    Akbar Salarvand

    2011-08-01

    Full Text Available In this study, nano crystalline Ni-20Cr-6Al composite powder was produced using a high energy planetary ball milling and a two-stage process. Then the oxidation behavior of coating of that superalloy at different temperatures considered. Nanostructured Ni-20Cr-6Al coating was deposited by cold spray for application as a bond coat to thermal barrier coating on industrial gas turbine components. The paper samples synthesized were characterized by scanning electron microscopy (SEM and transmission microscope (TEM. The crystallite size was found to be less than 18 nm. XRD pattern of the nanostructured Ni-20Cr-6Al milled powder consisted of two phases (Ni,Cr rich and (Ni3Al and so pure metals of Ni,Cr and Al that transferred into the coating. XRD pattern of the oxidized coating revealed that α-Al2O3 oxide was the main phase of the oxide and so Ni(Cr,Al 2O4 spinel phases despite the formation of α- Al2O3 oxide.

  11. The Electrochemical Behavior of Ni-base Metallic Glasses Containing Cr in H2SO4 Solutions

    International Nuclear Information System (INIS)

    In order to develop alloy resistance in aggressive sulphat ion, the corrosion behavior of metallic glasses Ni92.3Si4.5B32, Ni82,3Cr7Fe3Si4.5B3.2 and Ni75.5Cr13Fe4.2Si4.5B2.8 (at %) at different concentrations of H2SO4 solutions was examined by electrochemical methods and Scanning Electron Microscope (SEM) and X-ray Photoelectron Microscopy (XPS) analyses. The corrosion kinetics and passivation behavior was studied. A direct proportion was observed between the corrosion rate and acid concentration in the case of Ni92.3Si4.5B32 and Ni75.5Cr13Fe4.2Si4.5B2.8 alloys. Critical concentration was observed in the case of Ni82,3Cr7Fe3Si4.5B3.2 alloy. The influence of the alloying element is reflected in the increasing resistance of the protective film. XPS analysis confirms that the protection film on the Ni92.3Si4.5B32 alloy was NiS which is less protective than that formed on Cr containing alloys. The corrosion rate of Ni82,3Cr7Fe3Si4.5B3.2 and Ni75.5Cr13Fe4.2Si4.5B2.8. alloys containing 7% and 13% Cr are 7.90-26.1Χ10-3 mm/y which is lower about 43-54 times of the alloy Ni92.3Si4.5B32 (free of Cr). The high resistance of Ni75.5Cr13Fe4.2Si4.5B2.8 alloy at the very aggressive media may due to thicker passive film of Cr2O3 which hydrated to hydrated chromium oxyhydroxide

  12. 热处理对钽强化激光熔覆NiCrBSi涂层的影响%Influence of Heat Treatment on Laser Clad Ta Reinforced NiCrBSi Coating

    Institute of Scientific and Technical Information of China (English)

    余廷; 邓琦林; 姜兆华; 董刚; 杨建国

    2013-01-01

    通过在激光熔覆NiCrBSi涂层(Ni60)中添加钽(Ta)元素来提高900℃热处理后涂层的耐磨性.研究了900℃热处理对激光熔覆NiCrBSi和钽强化NiCrBSi复合涂层显微组织、硬度以及耐磨性能的影响.利用带能谱仪的扫描电镜和衍射仪分析涂层的显微组织和物相.通过盘-销实验评价涂层的耐磨性.结果表明:经过900℃热处理后涂层中的M7C3和M23C6发生了分解,钽强化复合涂层和纯NiCrBSi涂层中的硬度都有所下降,但由于复合涂层中原位生成的TaC未发生分解,使得其硬度和耐磨性都高于纯NiCrBSi涂层.%Tantalum element was used to improve wear resistance of laser clad NiCrBSi coating (Ni60) heat treated at 900℃. Microstructure, microhardness and wear resistance of the pure NiCrBSi and Ta reinforced NiCrBSi coatings were investigated. The coatings were analyzed by scanning electron microscope (SEM) with energy energy-dispersive spectrometer (EDS). The phase constitution was identified using X-ray diffraction (XRD) experiments. Dry sliding wear tests were carried out on a pin-on-disc tribometer to study wear behavior. The results show M7C3 and M23C6 carbides were decomposed after 900 ℃ heat treatment, which resulted in the decrease in the microhardness of the coatings. However, after the heat treatment, the Ta reinforced NiCrBSi composite coating had higher microhardness and wear resistance compared to pure NiCrBSi coating since in situ TaC particles in the composite coating were not decomposed due to its high thermal stability.

  13. Interdiffusion in the Ni-Cr-Co-Mo system at 1300/sup 0/C

    Energy Technology Data Exchange (ETDEWEB)

    Heaney, J.A. III; Dayananda, M.A.

    1985-01-01

    Interdiffusion was investigated with solid-solid diffusion couples in the ..cap alpha.. (fcc) region of the quaternary Ni-Cr-Co-Mo system at 1300/sup 0/C for the determination of diffusion paths and diffusional interactions among the components. The concentration profiles for a given couple exhibited a common cross-over composition, Y/sub c/, which reflected the relative depths of diffusion in the terminal alloys. Interdiffusion fluxes were calculated directly from the concentration profiles and the quaternary interdiffusion coefficients were calculated at selected compositions. Ni and Co exhibited up-hill diffusion against their individual concentration gradients in a direction opposite to the interdiffusion of Cr. Quaternary diffusion paths were presented as a set of partial diffusion paths on the basis of relative concentration variables.

  14. Examination of formability to seamless tubes on Ni-Cr-W superalloy

    International Nuclear Information System (INIS)

    Research and development have been carried out on the new superalloys as a component material for process heating high-temperature gas-cooled reactors with coolant outlet temperatures of around 1000degC, and the optimum chemical composition has already been proposed. The program had set some targets. One of them is formability to 32-mm-outer dia., 4- to 5-mm-thick, 7-m-long seamless tubes. Hence formability and solution treatment conditions were examined by producing seamless tubes from 2000 kg scale ingot of the proposed optimum Ni-Cr-W superalloy. Based on the obtained results, the following conclusions are drawn: (1) Newly developed Ni-Cr-W superalloy possesses sufficient formability to seamless tubes in both hot- and cold-workability. (2) The grain size of the seamless tubes can be adjusted in a range of ASTM No.2 to 3 by solution treated at 1230 to 1240degC. (author)

  15. Factors Affecting Transformation Temperatures in Fe-Mn-Si-Cr-Ni Shape Memory Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@The effects of prestrain and annealing temperature on phase transformation temperatures in Fe14Mn5Si8Cr4Ni shape memory alloy have been studied. The results showed that when the annealing temperature was 673 K, both the Af and the Ms temperatures increased appreciably as the prestrain increased, the As temperature increased slightly with increasing prestrain; the resistivity difference at 303 K between the heating and cooling curve also increased with increasing prestrain, which agreed with the recovery strain. The shape memory effect in Fe-Mn-Si-Cr-Ni shape memory alloy is caused by the stress-induced γ → ε martensite transformation and its reverse transformation. When the prestrain was 10%, the Ms temperature decreased remarkably as the annealing temperature increased.

  16. Oxidation protection of 20Cr-25Ni-Nb stainless steel at 1,300C

    International Nuclear Information System (INIS)

    20Cr-25Ni-Nb stabilized stainless steel is used as the fuel cladding in the United Kingdom advanced gas-cooled nuclear power plants. Enhanced environmental protection of chromia-forming advanced metallic alloys at normal operating temperature, typically approx-lt 900C, may be provided by two well-established approaches - incorporation of reactive elements into the protective oxide scale or an amorphous ceramic coating acting as a diffusion barrier. The continued effectiveness of such approaches, namely by cerium and yttrium ion implantation and with a vapor deposited amorphous silica coating, in reducing oxidation of 20Cr-25Ni-Nb stainless steel in a carbon-dioxide-based environment has been examined during 0.5 and 1 hr transients to 1,300C. The influence of pre-oxidation of the ion-implanted, silica-coated, and uncoated steel for extended periods in the same environment at 825-900C has also been established

  17. Surface and Electrical Properties of NiCr Thin Films Prepared by DC Magnetron Sputtering

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jicheng; TIAN Li; YAN Jianwu

    2008-01-01

    Several batches of NiCr alloy thin films with different thickness were prepared in a multi-targets magnetron sputtering apparatus by changing sputtering time while keeping sputtering target power of Ni and Cr fixed. Then the as-deposited films were characterized by energy-dispersive X-Ray spectrometer (EDX),Atomic Force Microscope (AFM) and four-point probe (FPP) to measure surface grain size, roughness and sheet resistance. The film thickness was measured by Alpha-Step IQ Profilers. The thickness dependence of surface roughness, lateral grain size and resistivity was also studied. The experimental results show that the grain size increases with film thickness and the surface roughness reaches the order of nanometer at all film thickness. The as-deposited film resistivity decreases with film thickness.

  18. Preparation of Semisolid Slurry for Stainless Steel 1Cr18Ni9Ti

    Institute of Scientific and Technical Information of China (English)

    MAO Wei-min; ZHAO Ai-min; YUN Dong; ZHANG Le-ping; ZHONG Xue-you

    2004-01-01

    The preparation of nondendritic semisolid slurry for stainless steel 1Cr18Ni9Ti was studied. The experiments show that when stirred for 2-3 min under the test condition, the semisolid slurry with solid of about 50 % and spherical primary austenite in size of 100-200 μm can be obtained, and besides the slurry is easy to flow out through the bottom hole of the stirring chamber. More homogeneous temperature fields and solute fields of stainless steel 1Cr18Ni9Ti melt appear because of the electromagnetic stirring, which restrains the formation of large primary austenitic dendrites and creates a base to form spherical crystals of primary austenite. The stronger temperature fluctuation in the melt containing many stirring-initiated rosette primary austenitic grains, together with the simultaneous remelting of the secondary arm roots primarily account for the deposition of the spherical primary austenitic grains.

  19. Positron annihilation studies on FeCrCoNi high entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Abhaya, S., E-mail: sab@igcar.gov.in; Rajaraman, R.; Kalavathi, S.; Amarendra, G.

    2015-01-25

    Highlights: • Defect annealing in FeCrCoNi high entropy alloy is studied using positron lifetime and Doppler broadening. • Variation of positron lifetime with temperature show the annealing of defects beyond 770 K. • XRD shows that the alloy forms FCC solid solution and the phase remains stable even after annealing at 1373 K. • Recrystallization assisted grain growth occurs beyond 973 K. - Abstract: Defect annealing in FeCrCoNi high entropy alloy is studied using positron lifetime and Doppler broadening spectroscopic techniques. Variation of positron lifetime with temperature show the annealing of defects beyond 770 K. Theoretical positron lifetime and electron momentum distributions were computed for the alloy to understand the nature of defects present in the arc melted alloy. X-ray diffraction measurements show that the arc melted alloy forms FCC solid solution and the phase remains stable even after annealing at 1373 K. Recrystallization assisted grain growth occurs beyond 973 K.

  20. Microstructure and properties of thermal-sprayed NiCrWRE coatings

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhenyu; WANG Zhiping; LIANG Bunv

    2008-01-01

    The powders of NiCrW and NiCrWRE alloys were flame sprayed on a medium-carbon steel substrate by thermal spray welding. The microstructure and tribological behavior of coatings were studied experimentally by means of scanning electron microscopy (SEM), field emission gun scanning electron microscope (FEGSEM), and wear tests. The addition of CeO2 modifies the coating morphology from a needle-like structure to a roughly cubic morphology; the refining and purifying effect of rare earth elements makes the microstructure more compact and finer. Analysis of the worn surfaces reveals that the coatings with CeO2 addition show improved abrasive wear resistance over those without CeO2. By adding CeO2, the hardness of the coatings is significantly increased, and the wear resistance of the coatings is enhanced.

  1. Effects of Te on intergranular embrittlement of a Ni-16Mo-7Cr alloy

    Science.gov (United States)

    Cheng, Hongwei; Han, Fenfen; Jia, Yanyan; Li, Zhijun; Zhou, Xingtai

    2015-06-01

    Te was deposited on the surface of a Ni-16Mo-7Cr alloy by thermal evaporation at 700 °C, and the effect of Te on the intergranular cracking behavior and the tensile properties of the alloy was investigated. The results show that the reaction products formed on the surface of the alloy, the diffusion depth of Te in the alloy, and the yield strength of the alloy attacked by Te at room temperature are not changed remarkably with Te content increasing, whereas the ultimate tensile strength and elongation of the alloy is decreased distinctly. The primary surface reaction product are mainly composed of Ni3Te2, CrTe, and MoTe2, and the diffusion depth of Te in the alloys is about 50 μm. The intergranular embrittlement mechanism of the alloy induced by Te of is also discussed in this paper.

  2. Deposition and Damping Property of Arc Ion Plated NiCrAlY Coatings%基底偏压对电弧离子镀NiCrAlY涂层阻尼性能的影响

    Institute of Scientific and Technical Information of China (English)

    杜广煜; 谭祯; 孙伟; 柴昊; 巴德纯; 韩清凯

    2012-01-01

    The NiCrAlY coatings were deposited by arc ion plating on stainless steel substrates. The effects of the deposition conditions, such as the pressure, substrate bias, and arc current, on damping property of the NiCrAlY coatings were evaluated. The rnicrostructures and damping property were characterized with X-ray diffraction, scanning electron microscopy and dynamic mechanical analyzer. The results show that the substrate bias significantly improves the damping properties of the NiCrAlY coating. For example, the damping factor of the NiCrAlY coated stainless steel substrate increased with an increase of the bias voltage. The fairly smooth, compact NiCrAlY coatings mainly consisted of γ-Ni, α-NiAl,γ-Ni3Al,and α- Cr phases.%采用电弧离子镀方法在不锈钢基片上制备了NiCrAlY涂层,在制备过程中改变基底偏压分别取50,100,200,300V.对涂层样品分别进行物相分析,表面形貌观察,测定微区化学成分,并利用动态机械分析仪(DMA)对涂层样品的阻尼性能进行测试.结果表明,利用电弧离子镀的方法可以在不锈钢基底上获得均匀的NiCrAlY涂层.涂层为晶态结构,主要由γ-Ni相,β-NiAl相,γ'-Ni3Al相和α-Cr组成.制备过程中的偏压变化对涂层的表面形貌有明显影响,对涂层的化学成分影响不大.DMA结果表明NiCrAlY涂层能明显地提高基底材料的阻尼性能,同时随着偏压增大,涂层样品的阻尼因子有所提高.

  3. Influence of deformation and annealing conditions on the recrystallization cube texture in the three-layer NiW/NiCr/NiW substrate tapes

    Science.gov (United States)

    Rodionov, D. P.; Khlebnikova, Yu. V.; Gervas'eva, I. V.; Egorova, L. Yu.; Kazantsev, V. A.

    2015-10-01

    The formation of a sharp cube texture in a three-layer composite tape with the outer (working) layers made of an Ni-4.8 at % W alloy and the inner layer made of an Ni-11 at % Cr alloy is studied after cold deformation by rolling at a reduction of 98.4-99.5% and subsequent recrystallization annealing at a temperature of 1000-1150°C. An analysis of the sharpness of the cube texture and the magnetic properties of the three-layer composite material shows that such tapes can be used as substrates to create second-generation HTSC. At a temperature of 80 K, the specific magnetization of the composite three-layer tape is lower than that of a widely used tape made of an Ni-5 at % W alloy.

  4. Phase Separation Process at Early Aging Stage of Ni42CrTiAl

    Institute of Scientific and Technical Information of China (English)

    Wei ying-hui; Hou li-feng; Jiao shao-yang; Hu lan-qing; Xu bing-she

    2004-01-01

    Phase separation process of Ni42CrTiAl alloy aged at various temperatures was studied by means of transmission electron microscope and X-ray diffraction. It was concluded that the temperature of spinodal decomposition is500℃. And the solid solution break into the lean and the rich areas, moreover the rich solute areas would have ordering arrangement to form ordering phase.

  5. Hydrogen embrittlement of cast 13% Cr 6% NiMo steel

    International Nuclear Information System (INIS)

    A study of the hydrogen embrittlement resistance of cast 13Cr6NiMo steel after various alternative tempering treatment is reported. The threshold levels of the stress intensity factor are examined as they relate to the residual austenite content in the structure of lath martensite, the type of fracture found on the specimens and the surface segregation of phosphorus observed on them. (author)

  6. Wear Behavior of a NiCr/AgVO3 Self-Lubricating Composite

    Institute of Scientific and Technical Information of China (English)

    Wenting ZHANG; Lingzhong DU; Hao LAN; Chuanbing HUANG; Weigang ZHANG

    2013-01-01

    NiCr/AgVO3 self-lubricating composite was prepared by powder cold-pressed method with the NiCr alloy as the matrix and 10 wt.% additive of AgVO3 as solid lubricant.The AgVO3 additive powder was synthesized by the precipitation method which exhibits a melting point of 460 ℃.Microstructure,phase composition and thermal properties of the AgVO3 powder,as well as the composite of NiCr/AgVO3 were analyzed using scanning electron microscopy (SEM),transmission electron microscopy (TEM),X-ray diffraction (XRD) and differential scanning calorimeter (DSC).The friction and wear behavior of the specimens from room temperature (R.T.)to 800 ℃ was evaluated using a ball-on-disk tribometer and 3D white light interference (WLI).The results showed that the friction coefficient of this material under atmosphere decreases with temperature increasing from R.T.to 800 ℃.However,the wear rate firstly increases from R.T.to 200 ℃,almost remains stable from 200 ℃ to 600 ℃,and then decreases with further increasing the temperature up to 800 ℃.It is also found that the prepared composite materials show a better frictional behavior than NiCr alloy over the whole range of temperatures,which is mainly attributed to solid lubrication of AgVO3 exhibiting a lamella-slip structure at temperatures below 460 ℃ and forms liquid-film at elevated temperatures above the melting point.

  7. The Effects of Aging Precipitation on the Recrystallization of CuNiSiCr Alloy

    Institute of Scientific and Technical Information of China (English)

    LEI Jingguo; HUANG Jinliang; LIU Ping; JING Xiaotian; ZHAO Dongmei; ZHI Xiao

    2005-01-01

    The interaction between precipitation and recrystallization and its effect on the properties of the Cu-Ni-Si-Cr alloy during aging were discussed.The results show that the deformation results in much more dispersed precipitation of the phases. The precipitations have accelerating or retarding effects on the recrystallization. On the formation and growth of recrystallization, the precipitated phases are coarsed or dissolved in front of grain boundaries following a re-precipitation in the recrystallization area.

  8. Formation of nanocrystalline during flash welding of 0Cr16Ni22Mo2Ti steel

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A nanocrystalline layer was fabricated in bond area of 0Cr16Ni22Mo2Ti austenite steel using flash welding. The mean grain size near bond line is about 20 nm, and the farther the distance from bond line, the larger the size of the nanocrystalline. The thickness of the nanocrystalline layer is about 50 mm. The formation mechanism of the nanocry- stalline may be that the metal in semisolid state is deformed severely and its solid grains are fragmented.

  9. The welding of austenitic-ferritic Mo-alloyed Cr-Ni-Steel

    International Nuclear Information System (INIS)

    This paper provides general information and guidance on the welding of austenitic-ferritic Mo-alloyed Cr-Ni stainless steel. Information is given on the various chemical compositions and on resistance to corrosion and on the mechanical and physical properties of commercially available steels. The effect of welding on the base metal and the selection of welding processes and welding consumables are described

  10. Testing of Neutron Data for Fe, Cr, Ni based on Integral Experiments

    Directory of Open Access Journals (Sweden)

    Tsibouliya A. M.

    2013-03-01

    Full Text Available In this work the modern evaluated nuclear data for structural materials such as Fe, Cr, Ni are considered, and comparison between the RUSFOND data file library and other libraries is done. Criticality calculations for a set of selected fast uranium and plutonium benchmarks are performed, and calculation results are compared with experimental data. Monte Carlo calculations were performed using continuous energy cross-sections corresponding to different data libraries.

  11. Effect of Slag Composition on Inclusions in Si-Deoxidized 18Cr-8Ni Stainless Steels

    Science.gov (United States)

    Ren, Ying; Zhang, Lifeng; Fang, Wen; Shao, Shijie; Yang, Jun; Mao, Weidong

    2016-04-01

    Laboratory experiments and thermodynamic calculation for the Si-deoxidized 18Cr-8Ni stainless steel with CaO-Al2O3-SiO2-CaF2-MgO-MnO slag were performed to investigate the effect of slag composition on inclusions in Si-deoxidized 18Cr-8Ni stainless steels. A high-basicity slag improved the cleanness of stainless steel, while a low basicity slag lowered the Al2O3 content in inclusions, lowering the melting temperature of inclusions and improving the deformability of inclusions. Approximately, 15 pct content of MgO in the initial slag was beneficial to reduce the corrosion of refractory and would not influence the composition of inclusions. The Al2O3 in slag should be lowered to a minimum to reduce the Al2O3 content in inclusions in Si-deoxidized 18Cr-8Ni stainless steel. The log X_{{{{Al}}_{ 2} {{O}}_{ 3} }}i + log X_{{MgO}}i - log X_{MnO}i - log X_{{{{SiO}}2 }}i of inclusions was expressed as a linear function of log a_{{{{Al}}_{ 2} {{O}}_{ 3} }}^{{s}} + log a_{{CaO}}^{{s}} - log a_{MnO}^{{s}} - log a_{{{{SiO}}2 }}^{{s}} of the slag, which was used to predict the composition of inclusions based on the activity of Al2O3, CaO, SiO2, and MnO in the slag. Moreover, the equilibrium curve of Al-O and the stability diagram of inclusions in Si-deoxidized 18Cr-8Ni stainless steel at 1873 K (1600 °C) were calculated.

  12. Magnetic and structural properties of nanosize Ni-Zn-Cr ferrite particles synthesized by combustion reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gama, L. [Department of Materials Engineering, Federal University of Campina Grande, 58970-000 Campina Grande, PB (Brazil)]. E-mail: lucianna@dema.ufcg.edu.br; Hernandez, E.P. [Department of Physics, Federal University of Pernambuco, 50670-901 Recife, PE (Brazil); Cornejo, D.R. [Institute of Physics, University of Sao Paulo, 05508-900 Sao Paulo, SP (Brazil)]. E-mail: cornejo@macbeth.if.usp.br; Costa, A.A. [Department of Physics, Federal University of Pernambuco, 50670-901 Recife, PE (Brazil)]. E-mail: aac@df.ufpe.br; Rezende, S.M. [Department of Physics, Federal University of Pernambuco, 50670-901 Recife, PE (Brazil)]. E-mail: rezende@df.ufpe.br; Kiminami, R.H.G.A. [Department of Materials Engineering, Federal University of Sao Carlos, 13565-905 Sao Carlos, SP (Brazil)]. E-mail: ruth@powder.ufscar.br; Costa, A.C.F.M. [Department of Materials Engineering, Federal University of Campina Grande, 58970-000 Campina Grande, PB (Brazil)]. E-mail: anacristina@dema.ufcg.edu.br

    2007-10-15

    This paper reports on Cr{sup 3+}-doped and undoped Ni-Zn nanosize ferrite obtained by reaction combustion synthesis. The powders resulting from this synthesis were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and their magnetic properties examined with an alternative gradient magnetometer (AGM) and by ferromagnetic resonance (FMR). The XRD results confirmed the formation of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} bulk spinel and small quantities of second phase hematite ({alpha}Fe{sub 2}O{sub 4}) to the powders without chromium. However, the powders containing 0.1 mol of chromium showed only a Ni-Zn ferrite cubic phase. The Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and Ni{sub 0.5}Zn{sub 0.5}Fe{sub 1.9}Cr{sub 0.1}O{sub 4} showed average crystallite sizes of 20.7 and 22.7 nm, respectively. The SEM micrographs of the powders to the sample without chromium reveals nanoparticles with a regular morphology without pre-sintering and with the presence of soft agglomerations. The powder with 0.1 mol of chromium displays homogeneous and finer nanoparticles, which are more reactive and hence more agglomerated. Saturation magnetization of the phase without Cr{sup 3+} was 61.97 emu/g, while that of the powder with chromium was 40.56 emu/g. The inclusion of chromium caused the magnetization index to drop by 34% and decreased the coercive field, H {sub c}, by 77%. It is known that the inclusion of chromium is advantageous for high-frequency transformer applications.

  13. The influence of chemical composition on structure and mechanical properties of austenitic Cr-Ni steels

    Directory of Open Access Journals (Sweden)

    A. Kurc-Lisiecka

    2013-12-01

    Full Text Available Purpose: The aim of the paper is to investigated the influence of the chemical composition on the structure and mechanical properties of austenitic Cr-Ni steels. Special attention was put on the effect of solution heat treatment on mechanical properties of examined steels. Design/methodology/approach: The examinations of static tensile tests were conducted on ZWICK 100N5A. Hardness measurements were made by Vickers method. The X-ray analyzes were realized with the use of Dron 2.0 diffractometer equipped with the lamp of the cobalt anode. The metallographic observations were carried out on LEICA MEF 4A light microscope. Findings: Results shown that after solution heat treatment the values of strength properties (UTS, YS0.2 and hardness (HV of both investigated steels decrease and their elongation (EL increases. The X5CrNi18-8 steel in delivery state shown austenitic microstructure with twins and numerous non-metallic inclusions, while in steel X10CrNi18-8 revealed a austenitic microstructure with numerous slip bands in areas with deformation martensite α’. The examined steels after solution heat treatment followed by water-cooling has the structure of austenite. Research limitations/implications: To investigate in more detail the influence of chemical composition on structure and mechanical properties the examinations of substructure by TEM should be conducted. Originality/value: The relationship between the solution heat treatment, structure and mechanical properties of investigated steels was specified.

  14. Precipitation behavior of AlxCoCrFeNi high entropy alloys under ion irradiation.

    Science.gov (United States)

    Yang, Tengfei; Xia, Songqin; Liu, Shi; Wang, Chenxu; Liu, Shaoshuai; Fang, Yuan; Zhang, Yong; Xue, Jianming; Yan, Sha; Wang, Yugang

    2016-01-01

    Materials performance is central to the satisfactory operation of current and future nuclear energy systems due to the severe irradiation environment in reactors. Searching for structural materials with excellent irradiation tolerance is crucial for developing the next generation nuclear reactors. Here, we report the irradiation responses of a novel multi-component alloy system, high entropy alloy (HEA) AlxCoCrFeNi (x = 0.1, 0.75 and 1.5), focusing on their precipitation behavior. It is found that the single phase system, Al0.1CoCrFeNi, exhibits a great phase stability against ion irradiation. No precipitate is observed even at the highest fluence. In contrast, numerous coherent precipitates are present in both multi-phase HEAs. Based on the irradiation-induced/enhanced precipitation theory, the excellent structural stability against precipitation of Al0.1CoCrFeNi is attributed to the high configurational entropy and low atomic diffusion, which reduces the thermodynamic driving force and kinetically restrains the formation of precipitate, respectively. For the multiphase HEAs, the phase separations and formation of ordered phases reduce the system configurational entropy, resulting in the similar precipitation behavior with corresponding binary or ternary conventional alloys. This study demonstrates the structural stability of single-phase HEAs under irradiation and provides important implications for searching for HEAs with higher irradiation tolerance. PMID:27562023

  15. Precipitation behavior of AlxCoCrFeNi high entropy alloys under ion irradiation

    Science.gov (United States)

    Yang, Tengfei; Xia, Songqin; Liu, Shi; Wang, Chenxu; Liu, Shaoshuai; Fang, Yuan; Zhang, Yong; Xue, Jianming; Yan, Sha; Wang, Yugang

    2016-08-01

    Materials performance is central to the satisfactory operation of current and future nuclear energy systems due to the severe irradiation environment in reactors. Searching for structural materials with excellent irradiation tolerance is crucial for developing the next generation nuclear reactors. Here, we report the irradiation responses of a novel multi-component alloy system, high entropy alloy (HEA) AlxCoCrFeNi (x = 0.1, 0.75 and 1.5), focusing on their precipitation behavior. It is found that the single phase system, Al0.1CoCrFeNi, exhibits a great phase stability against ion irradiation. No precipitate is observed even at the highest fluence. In contrast, numerous coherent precipitates are present in both multi-phase HEAs. Based on the irradiation-induced/enhanced precipitation theory, the excellent structural stability against precipitation of Al0.1CoCrFeNi is attributed to the high configurational entropy and low atomic diffusion, which reduces the thermodynamic driving force and kinetically restrains the formation of precipitate, respectively. For the multiphase HEAs, the phase separations and formation of ordered phases reduce the system configurational entropy, resulting in the similar precipitation behavior with corresponding binary or ternary conventional alloys. This study demonstrates the structural stability of single-phase HEAs under irradiation and provides important implications for searching for HEAs with higher irradiation tolerance.

  16. Microstructure of reactive synthesis TiC/Cr18Ni8 stainless steel bonded carbides

    Institute of Scientific and Technical Information of China (English)

    Jiang Junsheng; Liu Junbo; Wang Limei

    2008-01-01

    TiC/Cr18Ni8 steel bonded carbides were synthesized by vacuum sintering with mixed powders of iron, ferrotitanium, ferrochromium, colloidal graphite and nickel as raw materials. The microstructure and microhardness of the steel bonded carbides were analyzed by scanning electron microscope (SEM),X-ray diffraction (XRD) and Rockwell hardometer. Results show that the phases of steel bonded carbides mainly consist of TiC and Fe-Cr-Ni solid solution. The synthesized TiC particles are fine. Most of them are not more than 1 μm With the increase of sintering temperature, the porosity of TiC/Cr18Ni8 steel bonded carbides decreases and the density and hardness increase, but the size of TiC panicles slightly increases. Under the same sintering conditions, the density and hardness of steel bonded carbides with C/Ti atomic ratio 0.9 are higher than those with C/Ti atomic ratio 1.0.The TiC particles with C/Ti atomic ratio 0.9 are much finer and more homogeneous.

  17. Effects of Solute Concentrations on Kinetic Pathways in Ni-Al-Cr Alloys

    Science.gov (United States)

    Booth-Morrison, Christopher; Weninger, Jessica; Sudbrack, Chantal K.; Mao, Zugang; Seidman, David N.; Noebe, Ronald D.

    2008-01-01

    The kinetic pathways resulting from the formation of coherent gamma'-precipitates from the gamma-matrix are studied for two Ni-Al-Cr alloys with similar gamma'-precipitate volume fractions at 873 K. The details of the phase decompositions of Ni-7.5Al-8.5Cr at.% and Ni-5.2Al-14.2Cr at.% for aging times from 1/6 to 1024 h are investigated by atom-probe tomography, and are found to differ significantly from a mean-field description of coarsening. The morphologies of the gamma'-precipitates of the alloys are similar, though the degrees of gamma'-precipitate coagulation and coalescence differ. Quantification within the framework of classical nucleation theory reveals that differences in the chemical driving forces for phase decomposition result in differences in the nucleation behavior of the two alloys. The temporal evolution of the gamma'-precipitate average radii and the gamma-matrix supersaturations follow the predictions of classical coarsening models. The compositional trajectories of the gamma-matrix phases of the alloys are found to follow approximately the equilibrium tie-lines, while the trajectories of the gamma'-precipitates do not, resulting in significant differences in the partitioning ratios of the solute elements.

  18. Cavitation erosion behavior of WC coatings on CrNiMo stainless steel by laser alloying

    Institute of Scientific and Technical Information of China (English)

    Xiao-bin Zhang; Chang-sheng Liu; Xiao-dong Liu; Jiang Dong; Bo Yu

    2009-01-01

    The WC powder was precoated on the surface of CrNiMo stainless steel and then made into an alloying layer by using the laser alloying technique.Phases in the layers were investigated by X-ray diffraction (XRD) analysis and surface morphologies after cavitation erosion were observed with the help of scanning electron microscopy (SEM).The cavitation erosion behavior of the CrNiMo stainless steel and WC laser alloying layer in distilled water was tested with the help of ultrasonic vibration cavitation ero-sion equipment.The results showed that the thickness of the laser alloying layer was about 0.13 mm.The layer had a dense micro-structure, metallurgically bonded to the substrate, and no crack had been found.The cavitation erosion mass loss rate of the laser al-loying layer was only 2/5 that of the CrNiMo stainless steel.The layer had better cavitation resistance properties because of its met-allurgical combination and the strengthening effects of the precipitate phases.

  19. Low friction coefficient coatings Ni-Cr by magnetron sputtering, DC

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Hernandez, J.; Mandujano-Ruiz, A.; Torres-Gonzalez, J.; Espinosa-Beltran, F. J.; Herrera-Hernandez, H.

    2015-07-01

    Magnetron Sputter Deposition technique with DC was used for the deposition of Ni-Cr coatings on AISI 316 SS like substrate. The cathode with a nominal composition Ni-22 at% Cr was prepared by Mechanical Alloying (MA) technique, with a maximum milling time of 16 hours and, with a high energy SPEX 8000 mill. The coatings were made under Argon atmosphere at room temperature with a power of 100 W at different times of growth. Chemical composition, microstructure, topography, nano hardness and wear of the coatings were evaluated using the techniques of microanalysis by energy dispersive X-ray analyzer (EDAX), X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), Nano-indentation and pin-on-Disk, respectively. After milling, was not detected contamination in the mixtures. XRD analysis revealed that the microstructure of the Ni-Cr alloy was maintained in the coatings with respect to MA powders, with some degree of recrystallization. Nano hardness values were in the order of 8.8 GPa with a Youngs modulus of 195 GPa. The adhesion of the films was evaluated according to their resistance to fracture when these were indented at different loads using Vickers microhardness. The wear test results showed a decrease in the friction coefficient with respect to the increase of thickness films, getting a minimum value of 0.08 with a thickness of 1 μm and which correspond with the maximum growing time. (Author)

  20. Transformation and Precipitation Kinetics in 30Cr10Ni Duplex Stainless Steel

    Science.gov (United States)

    Fazarinc, Matevz; Terčelj, Milan; Bombač, David; Kugler, Goran

    2010-09-01

    To improve the microstructure during casting, hot forming, and heat treatment of 30Cr10Ni duplex stainless steel, accurate data on the precipitation and transformation processes at high temperatures are needed. In this article, the precipitation and transformation processes at various aging times in the temperature range 873 K to 1573 K (600 °C to 1300 °C) were studied. The 30Cr10Ni ferrous alloy contains a relatively large amount of Cr, Ni, and C, which results in a complex microstructure. In addition to the ferrite, austenite, and sigma phase, the M23C6 and MC carbides were also observed in the microstructure. The precipitation of the sigma phase was observed after just 3 minutes of aging, and after 30 minutes of aging at approximately 1053 K (780 °C), its fraction exceeded 40 pct. An intensive austenite-to-ferrite transformation was observed above 1423 K (1150 °C). Optical microscopy, energy-dispersive X-ray spectroscopy (EDS), electron backscattered diffraction (EBSD), and X-ray diffraction (XRD), as well as micro-indentation hardness, hardness, impact toughness, and tensile tests, were carried out to evaluate the obtained microstructures of aged samples.

  1. Corrosion resistance of Cr-Ni-Mo steel after sterilization process

    Directory of Open Access Journals (Sweden)

    Z. Paszenda

    2007-05-01

    Full Text Available Purpose: The aim of the work was to evaluate how the process of high pressure steam sterilization influences the pitting corrosion resistance of Cr-Ni-Mo steel used for implants production.Design/methodology/approach: Surfaces of samples were prepared by electrolytic polishing and chemical passivation. Samples were sterilized in steam with the use of different parameters of temperature, pressure and time. Corrosion resistance investigations were carried out with the use of potentiodynamic method. The test were realized in solution simulating human blood environment (artificial plasma at the temperature of 37±1ºC and pH = 7.2. Parameters describing the corrosion resistance have been determined on the basis of analysis of anodic polarization curves.Findings: High pressure steam sterilization process improves all parameters relating to pitting corrosion resistance of Cr-Ni-Mo implantation steel that is: corrosion potential Ecorr, breakdown potential Eb, polarization resistance Rp, corrosion current density icorr and corrosion rate. The increase of sterilization time for constant parameters of temperature and pressure of steam was the important factor which improved significantly the corrosion resistance of tested samples.Research limitations/implications: Further investigations of chemical composition of the layers formed during sterilization process are planed.Originality/value: The obtained results show the advantageous influence of passivation and high pressure steam sterilization on the pitting corrosion resistance of Cr-Ni-Mo steel in solution simulating human blood environment (artificial plasma.

  2. Precipitation behavior of AlxCoCrFeNi high entropy alloys under ion irradiation

    Science.gov (United States)

    Yang, Tengfei; Xia, Songqin; Liu, Shi; Wang, Chenxu; Liu, Shaoshuai; Fang, Yuan; Zhang, Yong; Xue, Jianming; Yan, Sha; Wang, Yugang

    2016-01-01

    Materials performance is central to the satisfactory operation of current and future nuclear energy systems due to the severe irradiation environment in reactors. Searching for structural materials with excellent irradiation tolerance is crucial for developing the next generation nuclear reactors. Here, we report the irradiation responses of a novel multi-component alloy system, high entropy alloy (HEA) AlxCoCrFeNi (x = 0.1, 0.75 and 1.5), focusing on their precipitation behavior. It is found that the single phase system, Al0.1CoCrFeNi, exhibits a great phase stability against ion irradiation. No precipitate is observed even at the highest fluence. In contrast, numerous coherent precipitates are present in both multi-phase HEAs. Based on the irradiation-induced/enhanced precipitation theory, the excellent structural stability against precipitation of Al0.1CoCrFeNi is attributed to the high configurational entropy and low atomic diffusion, which reduces the thermodynamic driving force and kinetically restrains the formation of precipitate, respectively. For the multiphase HEAs, the phase separations and formation of ordered phases reduce the system configurational entropy, resulting in the similar precipitation behavior with corresponding binary or ternary conventional alloys. This study demonstrates the structural stability of single-phase HEAs under irradiation and provides important implications for searching for HEAs with higher irradiation tolerance. PMID:27562023

  3. Study on wear resistant cast B-containing 1Cr18Ni9Ti stainless steel

    Institute of Scientific and Technical Information of China (English)

    Kuang Jiacai; Jiang Zhiqiang; Zhang Shiyin; Ye Chang; Liu Qicheng

    2009-01-01

    The developed 1Cr18Ni9Ti austenitic stainless steel containing 1.63 wt.%B have been characterized by X-ray diffraction (XRD), electron probe microanalyzer (EPMA), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Vickers microhardness measurement. The microstructural evolution and property of high boron stainless steel after solution treatment at the temperature of 1050℃ are also investigated. The results show that the main compositions of borides are Fe, Cr and B, and with small amount of Ni, Mn and C elements. Silicon is insoluble in the borides. The hardness of borides is over 1,500 HV. It has been found that borides do not decompose during solution treatment, but part of borides dissolves into the matrix. The effect of increasing the solubility of boron element in the austenitic matrix favours the hardness enhancement by 8.54%. High boron stainless steel has excellent wear resistance in corrosive environment. Lifetime of transfer pipe made of high boron-containing stainless steel is 1.5-1.8 times longer than that of boron-free 1Cr18Ni9Ti stainless steel.

  4. Cd and Ni transport and accumulation in the halophyte Sesuvium portulacastrum: implication of organic acids in these processes

    OpenAIRE

    Mnasri, Mejda; Ghabriche, Rim; Fourati, Emna; Zaier, Hanen; Sabally, Kebba; Barrington, Suzelle; Lutts, Stanley; Abdelly, Chedly; Ghnaya, Tahar

    2015-01-01

    The implication of organic acids in Cd and Ni translocation was studied in the halophyte species Sesuvium portulacastrum. Citric, fumaric, malic, and ascorbic acids were separated and quantified by HPLC technique in shoots, roots and xylem saps of plants grown on nutrient solutions added with 50 μM Cd, 100 μM Ni and the combination of 50 μM Cd + 100 μM Ni. Results showed that Cd had no significant impact on biomass production while Ni and the combination of both metals drastically affected pl...

  5. Cd and Ni transport and accumulation in the halophyte Sesuvium portulacastrum: implication of organic acids in these processes

    OpenAIRE

    Tahar eGhnaya

    2015-01-01

    The implication of organic acids in Cd and Ni translocation was studied in the halophyte species Sesuvium portulacastrum. Citric, fumaric, malic and ascorbic acids were separated and quantified by HPLC technique in shoots, roots and xylem saps of plants grown on nutrient solutions added with 50 µM Cd, 100 µM Ni and the combination of 50 µM Cd + 100 µM Ni. Results showed that Cd had no significant impact on biomass production while Ni and the combination of both metals drastically affected pla...

  6. Tensile properties and fracture surface of 07MnNiCrMoVDR steel welded joint at low temperature

    Institute of Scientific and Technical Information of China (English)

    Zhang Lihong; Chen Furong; Xie Ruijun

    2009-01-01

    The tensile properties and fracture surfuce of 07MnNiCrMoVDR steel welded joint at low temperature have been studied by universal testing machine and scanning electron microscope. The results show that the tensile properties of 07MnNiCrMoVDR steel welded joint are greatly affected by temperature. Tensile strength and yield strength of 07MnNiCrMoVDR steel welded joint increase, bat elongation and reduction of area decrease with temperature decreasing. The macro-fracture of 07 MnNiCrMoVDR steel welded joint exhibits that the shear lip is not significant and micro-fracture makes up of dimpled fracture and tear fracture, and dimple becomes tiny and uniform with temperature decreasing.

  7. Electronic and magnetic properties of Cr-Mn-Ni-Al compound with LiMgPdSb-type structure

    Science.gov (United States)

    Wang, L. Y.; Wang, X. T.; Guo, R. K.; Lin, T. T.; Liu, G. D.

    2016-10-01

    We investigate the electronic and magnetic properties of Cr-Mn-Ni-Al compound with a LiMgPdSn-type structure in three different atomic arrangement configurations (AAC) by using the first-principles calculations. It was found that Cr-Mn-Ni-Al compound with type I AAC exhibits a spin-gapless semiconductive characteristic. The type II AAC is the most stable one and exhibits an especial band structure where the Fermi level slightly crosses the top of the valence bands in spin-up channel and the bottom of conductive bands in spin-down channel, which leads to the electronic transport with the spin-resolved carrier type. The Cr-Mn-Ni-Al compound shows an ordinary metallic behavior in type III AAC. The three nonequivalent atomic arrangement configurations of Cr-Mn-Ni-Al are all in ferromagnetic ground state under their equilibrium lattice parameters.

  8. Synthesis, macroscopic and local probe characterization of AgCrO$_2$ and CdCr$_2$S$_4$

    CERN Document Server

    Oliveira, Gonçalo; Araujo, J P

    The search of new materials with new and/or enhanced physical properties has, nowadays, a strict relation with the evolution of technology. The hunt for systems exhibiting simultaneous (anti)ferroelectric and (anti)ferromagnetic orders has re-started in the last years, and remains as one of the hot topics for Physic, Chemistry and Materials Science scientific communities. This is triggered by the possibility to apply these materials into, ${e.g.}$, new multiferroic memories that could be written electrically and read magnetically (or vice-versa). This thesis presents an experimental study on two of these so-called multiferroic materials, the AgCrO$_2$ delafossite and CdCr$_2$S$_4$ spinel type compounds. Different methods have been tested for the synthesis of delafossite silver chromium oxide AgCrO$_2$ namely, solid state reaction (ssr) and sol-gel combustion. The processes were optimized regarding complexing/combusting agents, temperature and duration of the heat treatments, as well as the processing atmosphe...

  9. Anelastic effects connected with isothermal martensitic transformations in 24Ni4Mo austenitic and 12Cr9Ni4Mo maraging steels

    Energy Technology Data Exchange (ETDEWEB)

    Golovin, I.S. [Russian State Technol. Univ., Moscow (Russian Federation). Dept. of Mater.; Nilsson, J.-O. [Department of Physical Metallurgy, Steel Research and Development, AB Sandvik Steel, S-811 81, Sandviken (Sweden); Serzhantova, G.V.; Golovin, S.A. [Department of Physical Metallurgy, Tula State University, Lenin av. 90, 300600, Tula (Russian Federation)

    2000-09-28

    Anelasticity of the austenitic steel 24Ni5Mo and the stainless steel 12Cr9Ni4Mo has been investigated in the austenitic state after quenching with respect to isothermal martensitic transformation during cooling and subsequent heating. Maxima of anelasticity due to isothermal transformation at {approx}200 K (24Ni5Mo, 0.002% C) and {approx}250 K (12Cr9Ni4Mo; 0.01% C) coincided well with C-curve noses obtained by methods based on magnetic properties and electric resistivity. Corresponding internal friction maxima were found to be dependent on cooling or heating rate, quenching temperature and the frequency of oscillation and may therefore be described using the Delorme approximation. The activation energy of isothermal martensitic transformation calculated from the lower part of the C-curves estimated using the Borgenstam-Hillert and Arrhenius methods (3-8 kJ/mol for 24Ni5Mo and 15-20 kJ/mol for 12Cr9Ni4Mo) are comparable with the energy of impurity-dislocation interaction ({approx}10 kJ/mol) and interpreted as too low to be caused by diffusion processes: the activation energy for carbon diffusion in austenitic steel 24Ni5Mo is found to be {approx}135 kJ/mol and {approx}145 kJ/mol for austenite in two-phase 12Cr9Ni4Mo steel. An estimation showed that the activation energy for the isothermal martensitic transformation for the 24Ni5Mo alloy with so-called binary martensitic kinetics was higher in the vicinity of the nose of the C-curve, became lower with a decrease in temperature range and approached zero in the vicinity of the athermal martensitic point. A similar effect was not observed in the 12Cr9Ni4Mo steel. (orig.)

  10. Design and characterization of novel precipitation hardenable high Cr Ni-based superalloys

    DEFF Research Database (Denmark)

    Bihlet, Uffe; Dahl, Kristian Vinter; Somers, Marcel A. J.

    2012-01-01

    Among the Ni-based superalloys, Alloy 718 stands apart with the ability to be precipitation hardened after welding, by the slow formation of nano-scale γ’’ (Ni3Nb) particles. This slow formation gives it a very low crack susceptibility, which has made it widely applied since its introduction...... in the aircraft industry in the 1960’s. Five powder metallurgical Ni-based superalloys containing 35-45 wt % Cr and 4-6 wt % Nb were designed with the aim of maintaining the hardening mechanism found in Alloy 718, while drastically increasing the hot corrosion resistance. The alloys were manufactured...... and the actual precipitation of γ’’ was verified with TEM. The mechanical properties of the hardened P/M alloys are comparable to those of Alloy 718....

  11. The formation mechanism of eutectic microstructures in NiAl-Cr composites.

    Science.gov (United States)

    Tang, Bin; Cogswell, Daniel A; Xu, Guanglong; Milenkovic, Srdjan; Cui, Yuwen

    2016-07-20

    NiAl-based eutectic alloys, consisting of an ordered bcc matrix (B2) and disordered bcc fibers (A2), have been a subject of intensive efforts aimed at tailoring the properties of many of the currently used nickel-based superalloys. A thermodynamic phase field model was developed on a thermodynamic foundation and fully integrated with a thermo-kinetic database of the Ni-Al-Cr ternary system to elucidate the resulting peculiar eutectic microstructure. Invoking a variation of the liquid/solid interfacial thickness with temperature, we simulated the characteristic sunflower-like eutectic microstructures in the NiAl-Cr composites, consistent with experimental observations. The mechanism that governs the formation of the peculiar eutectic morphology was envisioned from the modeled evolutions associated with six sequential steps. Our calculations show that the conditional spinodal decomposition occurring in sequence could further trim and revise the microstructure of the eutectics by generating fine-domain structures, thereby providing an additional method to explore the novel NiAl-based eutectic composites with tunable properties at elevated temperatures. PMID:27385194

  12. Corrosion Behavior of Pure Cr, Ni, and Fe Exposed to Molten Salts at High Temperature

    Directory of Open Access Journals (Sweden)

    O. Sotelo-Mazón

    2014-01-01

    Full Text Available Corrosion resistance of pure Fe, Cr, and Ni materials exposed in NaVO3 molten salt at 700°C was evaluated in static air during 100 hours. The corrosion resistance was determined using potentiodynamic polarization, open circuit potential, and lineal polarization resistance. The conventional weight loss method (WLM was also used during 100 hours. The electrochemical results showed that Fe and Cr have a poor corrosion resistance, whereas pure Ni showed the best corrosion performance, which was supported by the passive layer of NiO formed on the metallic surface and the formation of Ni3V2O8 during the corrosion processes, which is a refractory compound with a higher melting point than that of NaVO3, which reduces the corrosivity of the molten salt. Also, the behavior of these materials was associated with the way in which their corresponding oxides were dissolved together with their type of corrosion attack. Through this study, it was confirmed that when materials suffer corrosion by a localized processes such as pitting, the WLM is not reliable, since a certain amount of corrosion products can be kept inside the pits. The corroded samples were analyzed through scanning electron microscopy.

  13. BDT and Creep Behaviors of NiAl-25 at. pct Cr Alloy at Various Temperatures

    Institute of Scientific and Technical Information of China (English)

    Guangye ZHANG; Xinghao DU; Jianting GUO; Hengqiang YE

    2005-01-01

    Brittle-to-ductile transition (BDT) behavior and creep behavior of extruded NiAl-25Cr alloy at elevated temperatures were investigated. The results reveal that the alloy exhibits obvious BDT behavior with the increase in temperature and BDT temperature (BDTT) is sensitive to initial strain rate. When the initial strain rate increases by two orders of magnitude, BDTT has an increase of approximate 80 K. The creep data in the temperature range of 1073~1123 K reveal two distinct regions of creep behavior in this material. At lower temperature, the creep characteristics are consistent with structural controlled creep process where creep deformation is controlled by dislocation climb. At higher temperature, the creep characteristics are consistent with mobility-controlled deformation where viscous glide of dislocations controls creep. The apparent activation energy determined by creep in both regions exceeds the value for lattice self-diffusion in NiAl by a considerable amount. This can be explained in terms of the simultaneous deformation of second phase particles (γ'-Ni3Al and α-Cr phase) along NiAl matrix during creep.

  14. Corrosion behavior of high purity Fe-Cr-Ni alloys in trans-passive condition

    International Nuclear Information System (INIS)

    The corrosion behavior of high-purity (99.99%) Fe-Cr-Ni alloys was investigated in 13 N nitric acid with/without Ce4+ ions to clarify the effect of impurities on the trans-passive corrosion of stainless steel. The following results were obtained. (1) Almost no intergranular corrosion was observed in the high-purity alloys, although the corrosion rate of the matrix region was nearly the same as that of a commercial stainless steel with the same Cr and Ni content. (2) Due to the improved intergranular corrosion resistance, the effect of the purification became significant in the corrosion condition with the grain-separation being predominant. (3) The high-purity alloys showed higher susceptivility to intergranular corrosion with aging treatment between 873 K and 1073 K. Although the sulfuric acid/copper sulfate test suggested the formation of Cr-depleted zones, a grain boundary micro-analysis using a FETEM with an EDX did not reveal any change in Cr content or impurity segregain along the grain boundaries. The mechanism of corrosion enhancement resulting from the aging treatment remains nuclear. (author)

  15. Structure and composition of higher-rhenium-content superalloy based on La-alloyed Ni-Al-Cr

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, Eduard V.; Koneva, Nina A. [Tomsk State University of Architecture and Building, Tomsk, 634003 (Russian Federation); Nikonenko, Elena L., E-mail: vilatomsk@mail.ru [Tomsk State University of Architecture and Building, Tomsk, 634003 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Popova, Natalya A.; Fedorischeva, Marina V. [Tomsk State University of Architecture and Building, Tomsk, 634003 (Russian Federation); Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation)

    2015-10-27

    The paper presents the transmission and scanning electronic microscope investigations of Ni-Al-Cr superalloy alloyed with additional Re and La elements. This superalloy is obtained by a directional solidification method. It is shown that such additional elements as Re and La result in formation of new phases in Ni-Al-Cr accompanied by considerable modifications of quasi-cuboid structure in its γ’-phase.

  16. Combined effect of thermal and irradiation embrittlement in the reactor pressure vessel CrNiMoV steel

    International Nuclear Information System (INIS)

    Combined effects of segregation and irradiation embrittlement in reactor pressure vessel CrNiMoV steel were studied. The study deals with an analysis of conditions affecting the 15Ch2NMFA type CrNiMoV steel susceptibility and the development of microsegregation processes in connection with temper brittleness formed on repeated annealing cycles. Microstructural analysis and results of tensile and impact testing for all the treatment conditions are presented. (orig.)

  17. Structure and composition of higher-rhenium-content superalloy based on La-alloyed Ni-Al-Cr

    International Nuclear Information System (INIS)

    The paper presents the transmission and scanning electronic microscope investigations of Ni-Al-Cr superalloy alloyed with additional Re and La elements. This superalloy is obtained by a directional solidification method. It is shown that such additional elements as Re and La result in formation of new phases in Ni-Al-Cr accompanied by considerable modifications of quasi-cuboid structure in its γ’-phase

  18. Study of Oxidation Behaviour of Bond Coating Nanocomposites Ni-20Cr-6Al Powder Synthesized by Mechanical Alloying

    OpenAIRE

    Akbar Salarvand; Vahid Shafi pour

    2011-01-01

    In this study, nano crystalline Ni-20Cr-6Al composite powder was produced using a high energy planetary ball milling and a two-stage process. Then the oxidation behavior of coating of that superalloy at different temperatures considered. Nanostructured Ni-20Cr-6Al coating was deposited by cold spray for application as a bond coat to thermal barrier coating on industrial gas turbine components. The paper samples synthesized were characterized by scanning electron microscopy (SEM) and transmiss...

  19. Absorption Reduction Capacity with Chromium (Cr and Cadmium (Cd Contaminants of Vetiver Phytoremediation Process on Compost Soil

    Directory of Open Access Journals (Sweden)

    Ahamad Zubair

    2016-01-01

    Full Text Available This study aims to analyze the large of reduction capacity of chromium metals and cadmium in the soil compost media and absorption capacity of chrome and cadmium in phytoremediation process of vetiver; to compare the reduction-absorption capacities of chromium and cadmium metals in phytoremediation process of vetiver (Vetivera zizanioides. The study was carried out for 2 months with a range of sampling every 7 days, and then analyzed by using Atomic Absorption Spectrophotometer (AAS. Contaminants used as artificial contaminants containing heavy metals chromium (Cr and cadmium (Cd. This study is an experimental research includes two variables. First, the variations of Cr concentrations used were 400 ppm, 600 ppm and 800 ppm and Cd concentrations used were 40 ppm, 60 ppm, 800 ppm. Secondly, the variations of total plant are 3, 6, and 9 plant. The period of observation is made every week. Planting media used is compost soil with compost and clay composition of 20%, 30% and 40%. The results of study showed that there are a significant relationship between the reduction capacity of Cr and Cd of compost soil and the absorption capacity of Cr and Cd for vetiver (Vetiveria zizanioides. The higher of Cr and Cd decreases in soil followed by increased levels of Cr and Cd in vetiver (Vetiveria zizanioides. The capacity of Cr reduction varies between 57% - 86% and Cd 36% - 64% where as the absorption capacity of vetiver on Cr between 38% - 75% and Cd between 34%-74%. The capacity of reduction-absorption of Cr is relatively higher than Cd in phytoremediation process of vetiver.

  20. Microstructure, precipitates and compressive properties of various holmium doped NiAl/Cr(Mo, Hf) eutectic alloys

    International Nuclear Information System (INIS)

    Highlights: → Trace Ho addition optimizes the microstructure of the NiAl/Cr(Mo, Hf) eutectic alloy. → An orientation relationship of [120]Ni2A13Ho//[111]NiA1 and (002-bar)Ni2A13Ho//(11-bar0)NiA1 is found. → Ho addition promotes the precipitation of Ni2AlHf Heusler phase. → Minor Ho addition coarsens the microstructure, especially the intercellular region. → More Ho addition changes the original cellular eutectic microstructure. -- Abstract: The microstructure and mechanical properties of NiAl-28Cr-6Mo-0.2Hf eutectic alloys with various holmium additions have been investigated by using of SEM, TEM and compression test. The results reveal that minor Ho addition could optimize the microstructure by refining the lamella inside of eutectic cell and controlling the coarsening of intercellular region. However the minor Ho addition results in the Ni2Al3Ho phase, which has hexagonal crystal structure and an orientation relationship with NiAl phase of [120]Ni2Al3Ho//[111]NiAl and (002-bar)Ni2Al3Ho//(11-bar0)NiAl. Moreover the Ni17Ho2 phase is found in the Ni2Al3Ho phase, which has twin crystal inside and an orientation relationship with Ni2Al3Ho phase of [123]Al17Ho2//[124]Ni2Al3Ho and (111-bar)Al17Ho2//(2-bar10)Ni2Al3Ho. In addition, the Ho addition promotes the precipitation of Ni2AlHf phase. More Ho addition coarsens the Cr(Mo) phases along the intercellular and results in more strengthening precipitates inside eutectic cell. When the Ho addition comes to 0.5 at.%, the alloy almost loses the cellular eutectic characteristic and exhibits a microstructure with coarse NiAl, massive Cr(Mo) and Ni2Al3Ho phases. The microstructure optimizations improve the mechanical properties of the alloy significantly, especially the alloy with 0.1 at.% Ho content.

  1. 激光重熔NiCrAlY涂层研究%Study on laser remelting NiCrAIY coating

    Institute of Scientific and Technical Information of China (English)

    郭永利; 祝超; 卢学刚; 梁工英; 董菲

    2011-01-01

    The bond coatings of NiCrAIY powder was coated on the substrate material of IN718 nickel alloy by air plasma spraying ( APS), and then it was remelted by 5 kW CO2 laser. The microstructure of the bond coatings was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and X-ray diffraction (XRD). The experimental results show that with the optimized remelting process, the bond coating displays superior metallurgical bonding with its substrate, and the mechanical bonding and layer structure of coatings by plasma spraying are changed, which is good for improving the mechanic performance of the coatings.Typical dendritic structure growing in cladding zone in the direction perpendicular to the substrate could strengthen the bond coating with its substrate. The dendritic structure is primarily made of metal Ni and Ni3A1 compounds,while some impurities and oxides such as A1203, Cr3O4 survived in flake exist in interdendritic structure. A dense oxide layer formed on the bonding surface can avoid O, diffusion, and effectively prevent the further oxidation of coatings and substrate, and improve the oxidation resistance of bond coatings.%采用空气等离子喷涂技术(APS)将NiCrAlY粉末作为粘结层材料喷涂在IN718镍基合金上,再用5 kW CO2连续激光器对其进行激光重熔处理,利用扫描电镜(SEM)、能谱分析(EDX)和X射线衍射(XRD)等手段对等离子喷涂层和激光重熔层的微观组织与成分进行了比较分析.结果表明:应用优化激光重熔工艺进行重熔后,涂层与基底形成冶金结合,改变了等离子喷涂层与基底的机械结合以及层状结构,有利于提高涂层的力学性能.重熔区组织为垂直基底向内部发散生长的树枝晶,加强了涂层与基底的结合.涂层中的树枝晶内部组织为Ni和Ni3Al,晶间则是被树枝晶凝固生长时排出的Al2O3,Cr2O3等呈片状生长的氧化物和杂质.涂层表面形成一层致

  2. Enhancement of the recycling of waste Ni-Cd and Ni-MH batteries by mechanical treatment.

    Science.gov (United States)

    Huang, Kui; Li, Jia; Xu, Zhenming

    2011-06-01

    A serious environmental problem was presented by waste batteries resulting from lack of relevant regulations and effective recycling technologies in China. The present work considered the enhancement of waste Ni-Cd and Ni-MH batteries recycling by mechanical treatment. In the process of characterization, two types of waste batteries (Ni-Cd and Ni-MH batteries) were selected and their components were characterized in relation to their elemental chemical compositions. In the process of mechanical separation and recycling, waste Ni-Cd and Ni-MH batteries were processed by a recycling technology without a negative impact on the environment. The technology contained mechanical crushing, size classification, gravity separation, and magnetic separation. The results obtained demonstrated that: (1) Mechanical crushing was an effective process to strip the metallic parts from separators and pastes. High liberation efficiency of the metallic parts from separators and pastes was attained in the crushing process until the fractions reached particle sizes smaller than 2mm. (2) The classified materials mainly consisted of the fractions with the size of particles between 0.5 and 2mm after size classification. (3) The metallic concentrates of the samples were improved from around 75% to 90% by gravity separation. More than 90% of the metallic materials were separated into heavy fractions when the particle sizes were larger than 0.5mm. (4) The size of particles between 0.5 and 2mm and the rotational speed of the separator between 30 and 60 rpm were suitable for magnetic separation during industrial application, with the recycling efficiency exceeding 95%. PMID:21295459

  3. The effect of ion implantation on the oxidation resistance of vacuum plasma sprayed CoNiCrAlY coatings

    International Nuclear Information System (INIS)

    Highlights: ► We used ion implantation to improve the oxidation resistance of CoNiCrAlY coating. ► The oxidation process of CoNiCrAlY coating at 1100 °C for 1000 h was studied. ► The Nb ion implanted coating exhibited better oxidation resistance. ► The influences of Nb and Al ion implantation into CoNiCrAlY coatings were evaluated. - Abstract: CoNiCrAlY coatings prepared by vacuum plasma spraying (VPS) were implanted with Nb and Al ions at a fluence of 1017 atoms/cm2. The effects of ion implantation on the oxidation resistance of CoNiCrAlY coatings were investigated. The thermally grown oxide (TGO) formed on each specimen was characterized by XRD, SEM and EDS, respectively. The results showed that the oxidation process of CoNiCrAlY coatings could be divided into four stages and the key to obtaining good oxidation resistance was to remain high enough amount of Al and promote the lateral growth of TGO. The implantation of Nb resulted in the formation of continuous and dense Al2O3 scale to improve the oxidation resistance. The Al implanted coating could form Al2O3 scale at the initial stage, however, the scale was soon broken and TGO transformed to non-protective spinel.

  4. Microstructure and He desorption behaviors of He charged FeCrNi-based films fabricated by direct current magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Song, L. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei 230031 (China); Wang, X.P., E-mail: xpwang@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei 230031 (China); Liu, F. [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031 (China); Gao, Y.X. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei 230031 (China); Zhang, T., E-mail: zhangtao@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei 230031 (China); Luo, G.N. [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031 (China); Fang, Q.F.; Liu, C.S. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei 230031 (China)

    2015-08-31

    He-charged FeCrNi-based films were prepared at different temperatures in a mixed atmosphere of He and Ar by direct-current magnetron sputtering method. X-ray diffraction and energy dispersive spectrometry analysis confirmed the typical austenitic structure of the deposited FeCrNi films and the compositions were in good accordance with 304 stainless steel target. Cross-sectional scanning electron microscopy images revealed the dense columnar nanocrystalline structure of the fabricated FeCrNi films. Nanoindentation measurements showed that the film fabricated at 300 °C exhibited the highest hardness value of 11.5 GPa. He desorption from FeCrNi-based films was traced by thermal desorption spectroscopy; the relatively low He desorption temperature range (150 °C–450 °C) implied that the charged He atoms were mainly located in interstitial sites of FeCrNi-based films. - Highlights: • He-charged columnar nanocrystalline FeCrNi films were prepared by DC magnetron sputtering. • Substrate temperature of 300 °C and He/Ar ratio 1:1 were the best sputtering parameters. • Compact and uniform microstructure obtained at 300 °C resulted in stable, high hardness. • Two He atoms' absorption/desorption mechanisms were revealed by TDS.

  5. Electrochemical corrosion behavior of Cu-40Ni-20Cr alloys with different grain sizes in solutions containing chloride ions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The electrochemical corrosion behavior of the two Cu-40Ni-20Cr alloys prepared by conventional casting(CA) and mechanical alloying(MA) with the different grain sizes was studied by using open-circuit potential(OCP), potentiodynamic polarization and electrochemical impedance spectroscopy(EIS) methods in solutions containing chloride ions. The results show that the free corrosion potentials of the two alloys move towards negative values, corrosion currents increase and therefore corrosion rates become faster with the increase of chloride ion concentrations. EIS plots of CACu-40Ni-20Cr alloy are composed of single capacitive loop, while EIS plots of MACu-40Ni-20Cr alloy are composed of double capacitive loops in solution containing lower chloride ion concentrations. EIS plots of the two alloys have Warburg impedance with the increase of chloride ion concentrations.Corrosion rates of MACu-40Ni-20Cr alloy become faster than those of CACu-40Ni-20Cr alloy obviously in solutions containing the same chloride ion concentrations because MACu-40Ni-20Cr alloy is able to produce large concentrations of grain boundaries in the course of reduction in grain size by mechanical alloying.

  6. Vacuum-Aided Recovery Technology of Spent Ni-Cd Batteries

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Recovery of Ni-Cd batteries was studied by a self-designed vacuum-aided recovering system under laboratory condi-tions. The fundamental research on a process of disassembling and recovering selected materials from Ni-Cd batterieswas conducted. The impacts of temperature, pressure and time were studied respectively. The mechanism of vac-uum thermal recovering was also discussed. The results show that: Ni-Cd batteries can be recovered effectively by vacuum-aided recovering system at 573~1173 K. At constant pressure, the increase of temperature can improve theseparating efficiency of cadmium. When the temperature is 1173 K, the cadmium can evaporate completely fromthe residue during 3 h at 10 Pa. The reduction of pressure in the certain range is effective to separate cadmium byvacuum distillation. Distillation time is a very important factor affecting separation of cadmium.

  7. Determination of Cd, Cr and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy

    Science.gov (United States)

    Nunes, Lidiane Cristina; de Carvalho, Gabriel Gustinelli Arantes; Santos, Dario; Krug, Francisco José

    2014-07-01

    A validated method for quantitative determination of Cd, Cr, and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy (LIBS) is presented. Laboratory samples were comminuted and homogenized by cryogenic or planetary ball milling, pressed into pellets and analyzed by LIBS. The experimental setup was designed by using a Q-switched Nd:YAG at 1064 nm with 10 Hz repetition rate, and the intensity signals from Cd II 214.441 nm, Cr II 267.716 nm and Pb II 220.353 nm emission lines were measured by using a spectrometer furnished with an intensified charge-coupled device. LIBS parameters (laser fluence, lens-to-sample distance, delay time, integration time gate, number of sites and number of laser pulses per site) were chosen after univariate experiments with a pellet of NIST SRM 695 (Trace Elements in Multi-Nutrient Fertilizer). Calibration and validation were carried out with 30 fertilizer samples from single superphosphate, triple superphosphate, monoammonium phosphate, and NPK mixtures. Good results were obtained by using 30 pulses of 50 J cm- 2 (750 μm spot size), 2.0 μs delay time and 5.0 μs integration time gate. No significant differences between Cd, Cr, and Pb mass fractions determined by the proposed LIBS method and by ICP OES after microwave-assisted acid digestion (AOAC 2006.03 Official Method) were found at 95% confidence level. The limits of detection of 1 mg kg- 1 Cd, 2 mg kg- 1 Cr and 15 mg kg- 1 Pb and the precision (coefficients of variation of results ranging from 2% to 15%) indicate that the proposed LIBS method can be recommended for the determination of these analytes in phosphate fertilizers.

  8. Competitive sorption of Cd, Cu, Mn, Ni, Pb and Zn in polluted and unpolluted calcareous soils.

    Science.gov (United States)

    Jalali, Mohsen; Moradi, Fahimeh

    2013-11-01

    The objectives of this study were to investigate competitive sorption behaviour of heavy metals (Cd, Cu, Mn, Ni, Pb and Zn) under different management practices and identify soil characteristics that can be correlated with the retention and mobility of heavy metals using 65 calcareous soil samples. The lowest sorption was found for Mn and Ni in competition with the other metals, indicating the high mobility of these two cations. The Freundlich equation adequately described heavy metals adsorption. On the basis of Freundlich distribution coefficient, the selectivity sequence of the metal adsorption was Cu > Pb > Cd > Zn > Ni > Mn. The mean value of the joint distribution coefficient (K dΣsp) was 182.1, 364.1, 414.7, 250.1, 277.7, 459.9 and 344.8 l kg(-1) for garden, garlic, pasture, potato, vegetables, wheat and polluted soils, respectively. The lowest observed K dΣsp in garden soil samples was due to the lower cation exchange capacity and lower carbonate content. The results of the geochemical modelling under low and high metal addition indicated that Cd, Ni, Mn and Zn were mainly retained via adsorption, while Pb and Cu were retained via adsorption and precipitation. Stepwise forward regression analysis showed that clay, organic matter and CaCO3 were the most important soil properties influencing competitive adsorption of Cd, Mn, Ni and Zn. The results in this study point to a relatively easy way to estimate distribution coefficient values. PMID:23677680

  9. Interface bonding of NiCrAlY coating on laser modified H13 tool steel surface

    Science.gov (United States)

    Reza, M. S.; Aqida, S. N.; Ismail, I.

    2016-06-01

    Bonding strength of thermal spray coatings depends on the interfacial adhesion between bond coat and substrate material. In this paper, NiCrAlY (Ni-164/211 Ni22 %Cr10 %Al1.0 %Y) coatings were developed on laser modified H13 tool steel surface using atmospheric plasma spray (APS). Different laser peak power, P p, and duty cycle, DC, were investigated in order to improve the mechanical properties of H13 tool steel surface. The APS spraying parameters setting for coatings were set constant. The coating microstructure near the interface was analyzed using IM7000 inverted optical microscope. Interface bonding of NiCrAlY was investigated by interfacial indentation test (IIT) method using MMT-X7 Matsuzawa Hardness Tester Machine with Vickers indenter. Diffusion of atoms along NiCrAlY coating, laser modified and substrate layers was investigated by energy-dispersive X-ray spectroscopy (EDXS) using Hitachi Tabletop Microscope TM3030 Plus. Based on IIT method results, average interfacial toughness, K avg, for reference sample was 2.15 MPa m1/2 compared to sample L1 range of K avg from 6.02 to 6.96 MPa m1/2 and sample L2 range of K avg from 2.47 to 3.46 MPa m1/2. Hence, according to K avg, sample L1 has the highest interface bonding and is being laser modified at lower laser peak power, P p, and higher duty cycle, DC, prior to coating. The EDXS analysis indicated the presence of Fe in the NiCrAlY coating layer and increased Ni and Cr composition in the laser modified layer. Atomic diffusion occurred in both coating and laser modified layers involved in Fe, Ni and Cr elements. These findings introduce enhancement of coating system by substrate surface modification to allow atomic diffusion.

  10. Comparative Studies on Temperature Dependent I-V Characteristics of Al/(p)CdTe and Ni/(n)CdS Schottky Junctions and Their PV Effect

    International Nuclear Information System (INIS)

    Temperature dependent I-V characteristics of vacuum evaporated Al/(p)CdTe and Ni/(n)CdS Schottky junctions and their photovoltaic effects have been studied and compared. Different junction parameters such as ideality factors, barrier heights, Richardson's constant, short-circuit current density, fill factor, PV efficiency etc. were determined from their I-V characteristics. These parameters were found to change significantly on variation of temperature. The structures showed the change of PV effect. Efficiency found were 2.84% for Al/(p)CdTe and 4.44% for Ni hydro/(n)CdS. Polycrystalline nature, and continuous and ordered structure with bigger grain sizes of the CdS film shows more PV conversion efficiency in making Ni/(n)CdS junction as compare to Al/(p)CdTe junction. However these values were found to vary with doping concentration, and in hydrogen treated samples in both cases.

  11. Geospatial Mapping of Pb, Cr, Cu, Zn, Cd, and Sb in Urban Soil, Cd. Juarez, Chihuahua, Mexico

    Science.gov (United States)

    Amaya, M. A.; Grimida, S. E.; Elkekli, A. R.; Aldouri, R. K.; Benedict, B. A.; Pingitore, N. E., Jr.

    2015-12-01

    Population-based random stratified sampling of the city of Cd. Juarez, Chihuahua, Mexico provided 500 city blocks for study. We collected soil from the public space (where present) in front of each house on a selected block; equal measured small volumes of these were combined to produce a composite sample for analysis. Such composite samples (1) decrease, by an order of magnitude, laboratory processing and analysis costs, and (2) smooth the data to represent blocks as averages of individual houses. Retention of the unanalyzed samples of the individual houses permits their later analysis should the composites suggest further study of individual houses on an anomalous block. Elemental analysis of 10 mg pressed powders was performed on a Panalytical Epsilon5 EDS-XRF, via 8 secondary targets and 12 USGS and NIST multi-element rock standards. The mean and (range) of concentration for Pb was 43 (13-550) ppm; for Cr, 31 (1.8-76); for Cu, 22 (6-550); for Zn 84 (42-415) ppm; for Cd, 1.9 (0.1-6.2); and for Sb, 5.9 (2.7-29). The old urban core of Cd. Juarez was marked by high levels of Pb, Cr, Cu, and Zn, and, to a smaller degree, of Cd and Sb. This pattern mirrors that of contiguous El Paso, Texas, USA, directly across the narrow Rio Grande. Businesses, industrial facilities, transportation (both railroads and highways), traditional "downtown" shopping, and old residential districts cluster in this urban core. A Pb-Cu-Zn smelter, which operated for more than a century until 1999, is present in the US adjacent to the Rio Grande, about two km away from downtown Cd. Juarez. Thus the city has been subject to both traditional metal sources (e.g., leaded gasoline, highway debris) and smelter emissions. The poplation of Cd. Juarez has exploded in the last few decades to some 1.5 million inhabitants due both to natural growth and in-migration from rural districts for economic opportunity. Most of this growth has been accommodated by radial expansion of the city into the surrounding

  12. Optimization of Heat Treatment of CuNiSiCrRE Alloy%CuNiSiCrRE合金热处理工艺的优化

    Institute of Scientific and Technical Information of China (English)

    郭宇航; 支海军; 吕秀芬; 师学礼

    2011-01-01

    By means of Brinell hardness tester and eddy-current conductometer as well as SEM, the effects of solid solution temperature, aging and cold deforming before aging on microstructure and properties of the CuNiSiCrRE alloy were studied, then the optimum heat treatment was detennined The results show that the optimized heat treatment process was solution at 900 ℃ for 1. 5 h with cooling in water, 40% cold-working and aging at 480 ℃ for 2 h with cooling in air. The hardness was 229 HB, electrical conductivity was 45. 6%IACS, tensile strength reached 674 MPa, yield strength was 641 MPa, elongation was 16 % and softening temperature was 540 ℃. Tensile fracture was ductile fracture.%采用布氏硬度计、涡流导电仪和扫描电子显微镜等研究了固溶温度、时效及时效前冷变形量对CuNiSiCrRE合金显微组织和性能的影响,在此基础上确定了其最佳热处理工艺.结果表明:该合金的最佳热处理工艺为900℃×1.5h固溶水冷+40%的冷变形+480℃×2h时效空冷,其相应的硬度为229HB,电导率为45.6%lACS,抗拉强度为674MPa,屈服强度为641MPa,伸长率为16%,软化温度为540℃,拉伸断口为韧性断裂.

  13. Bacillus cereus Cr2产NiR酶能力及其与除Cr(Ⅵ)效率的相关性%Study on the Production of NiR by Bacillus cereus Cr2 and the Correlation between the Enzyme and Removal Rate of Cr (Ⅵ)

    Institute of Scientific and Technical Information of China (English)

    赵欣欣; 许燕滨; 屈毛毛; 孙浩; 阮晶晶; 侯毛宇; 陈锦良

    2013-01-01

    目的:研究除铬优势菌Bacillus cereus Cr2的亚硝酸还原酶(nitrite reductase,NiR)产生情况,以及在Cr(Ⅵ)去除中的作用.方法:通过液体发酵培养和超声破碎的方法获得NiR粗酶液,采用改良的格里斯染色法比较了不同培养温度、pH值、Cr(Ⅵ)诱导浓度及磁场对NiR酶活性的影响,获得最佳产酶条件,进而研究NiR酶活与除铬优势菌去除Cr(Ⅵ)效率之间的关系.结果:细菌产酶的最佳条件是:温度为37℃,pH为6.5,Cr(Ⅵ)诱导浓度为80 mg/L,外加15 mT磁场,酶活力达到30 U/mL,培养体系中的Cr(Ⅵ)诱导浓度低于120 mg/L时不抑制酶活力,此时,NiR酶对Cr(Ⅵ)的去除率比Bacillus cereus Cr2提高10%以上(P<0.05).结论:NiR酶的存在是Bacillus cereus Cr2除Cr(Ⅵ)的机理.

  14. Separation of Cd and Ni from Ni-Cd batteries by an environmentally safe methodology employing aqueous two-phase systems

    Energy Technology Data Exchange (ETDEWEB)

    Lacerda, Vania Goncalves; Mageste, Aparecida Barbosa; Santos, Igor Jose Boggione; da Silva, Luis Henrique Mendes; da Silva, Maria do Carmo Hespanhol [Grupo de Quimica Verde Coloidal e Macromolecular, Departamento de Quimica, Centro de Ciencias e Tecnologicas, Universidade Federal de Vicosa, Av. P.H. Rolfs s/n, Campus da UFV, Vicosa, 36570-000 (Brazil)

    2009-09-05

    The separation of Cd and Ni from Ni-Cd batteries using an aqueous two-phase system (ATPS) composed of copolymer L35, Li{sub 2}SO{sub 4} and water is investigated. The extraction behavior of these metals from the bottom phase (BP) to the upper phase (UP) of the ATPS is affected by the amount of added extractant (potassium iodide), tie-line length (TLL), mass ratio between the phases of the ATPS, leaching and dilution factor of the battery samples. Maximum extraction of Cd (99.2 {+-} 3.1)% and Ni (10.6 {+-} 0.4)% is obtained when the batteries are leached with HCl, under the following conditions: 62.53% (w/w) TLL, concentration of KI equal to 50.00 mmol kg{sup -1}, mass ratio of the phases equal to 0.5 and a dilution factor of battery samples of 35. This novel methodology is efficient to separate the metals in question, with the advantage of being environmentally safe, since water is the main constituent of the ATPS, which is prepared with recyclable and biodegradable compounds. (author)

  15. The role of complement receptors type 1 (CR1, CD35) and 2 (CR2, CD21) in promoting C3 fragment deposition and membrane attack complex formation on normal peripheral human B cells

    DEFF Research Database (Denmark)

    Nielsen, Claus Henrik; Pedersen, Morten Løbner; Marquart, Hanne Vibeke Hansen;

    2002-01-01

    Normal human B lymphocytes are known to activate the alternative pathway (AP) of complement, leading to C3-fragment deposition and membrane attack complex (MAC) formation. The process is mediated via complement receptor type 2 (CR2, CD21), with complement receptor type 1 (CR1, CD35) playing...... a subsidiary role. In this study, we examine the relative contributions of CR1 and CR2 to the deposition of C3 fragments and MAC on B lymphocytes under circumstances where all complement pathways are operational. C3-fragment deposition and MAC formation were assessed on human peripheral B lymphocytes...... in the presence of 30% autologous serum. Blocking the CR2 ligand-binding site with monoclonal antibody (mAb) FE8 resulted in significant reduction (37.9+/-11.9%) in C3-fragment deposition, whereas MAC formation was only marginally affected (12.1+/-22.2% reduction). Blocking the CR1 binding-site resulted...

  16. The role of complement receptors type 1 (CR1, CD35) and 2 (CR2, CD21) in promoting C3 fragment deposition and membrane attack complex formation on normal peripheral human B cells

    DEFF Research Database (Denmark)

    Nielsen, Claus Henrik; Pedersen, Morten Løbner; Marquart, Hanne Vibeke;

    2002-01-01

    Normal human B lymphocytes are known to activate the alternative pathway (AP) of complement, leading to C3-fragment deposition and membrane attack complex (MAC) formation. The process is mediated via complement receptor type 2 (CR2, CD21), with complement receptor type 1 (CR1, CD35) playing a...... subsidiary role. In this study, we examine the relative contributions of CR1 and CR2 to the deposition of C3 fragments and MAC on B lymphocytes under circumstances where all complement pathways are operational. C3-fragment deposition and MAC formation were assessed on human peripheral B lymphocytes in the......) bearing CR1, however, markedly reduced both C3-fragment deposition and MAC formation. Our data suggest that C3-fragment deposition and MAC formation on B lymphocytes in vivo may involve both AP and classical pathway activation, with CR1 contributing significantly to the latter. On the other hand, the...

  17. Performance of Arc Ion Plated NiCoCrAlY Coating on Gun Steel%炮钢表面电弧离子镀NiCoCrAlY涂层的性能研究

    Institute of Scientific and Technical Information of China (English)

    郭策安; 张健; 郭秋萍; 张家东

    2013-01-01

    用电弧离子镀技术在炮钢表面沉积NiCoCrAlY涂层,研究了涂层的硬度与摩擦磨损性能、高温抗氧化性及耐腐蚀性.结果表明:涂层的硬度较炮钢提高了近36%,炮钢的磨损机制主要为严重的磨料磨损和塑性流动,NiCoCrAlY涂层磨损机制主要是粘着磨损,NiCoCrAlY涂层的摩擦系数(0.57~0.65)小于炮钢的摩擦系数(0.78~0.86);NiCoCrAlY涂层在850℃空气中氧化100 h后的动力学结果表明,涂层大大提高了炮钢的高温抗氧化性能,其原因是表面形成了θ-Al2O3和α-Al2O3氧化膜阻止了炮钢基体被氧化,同时NiCoCrAlY涂层由β-(Ni,Co)Al、α-Cr与γ-Ni相转变为γ-Ni、γ’-Ni3Al和FeNi相;NiCoCrAlY涂层在3.5%NaCl溶液中较炮钢自腐蚀电位提高了近200 mV,能够显著提高炮钢的抗腐蚀能力.

  18. MICROSTRUCTURE AND OXIDATION RESISTANCE OF NiCoCrAlYTa COATING BY LOW PRESSURE PLASMA SPRAYING

    OpenAIRE

    X.-H. LIANG; K. S. ZHOU; M. Liu; R. J. HONG; C. G. DENG; Luo, S.; Z. K. CHEN

    2009-01-01

    The NiCoCrAlYTa coating was prepared on Ni-based single crystal super-alloys by low pressure plasma spraying (LPPS). The phases and microstructures for the coatings were characterized by X-ray diffraction and scanning electron microscopy, and the fracture toughness and micro-hardness for both coatings and substrate were also investigated. The relationship between coating properties and oxidation was analyzed. The result shows that elementary distribution of NiCoCrAlYTa coatings, which consist...

  19. Wear Micro-Mechanisms of Composite WC-Co/Cr - NiCrFeBSiC Coatings. Part I: Dry Sliding

    OpenAIRE

    D. Kekes; P. Psyllaki; M. Vardavoulias

    2014-01-01

    The influence of the cermet fraction in cermet/ metal composite coatings developed by High-Velocity Oxyfuel Flame (HVOF) spraying on their tribological behaviour was studied. Five series of coatings, each one containing different proportion of cermet-metal components, prepared by premixing commercially available feedstocks of NiCrFeBSiC metallic and WC-Co/Cr cermet powders were deposited on AISI 304 stainless steel substrate. The microstructure of as-sprayed coatings was characterized by part...

  20. Wear Micro-Mechanisms of Composite WC-Co/Cr - NiCrFeBSiC Coatings. Part II: Cavitation Erosion

    OpenAIRE

    D. Kekes; P. Psyllaki; M. Vardavoulias; Vekinis, G.

    2014-01-01

    Composite coatings with five different proportions of WC-Co/Cr and NiCrFeBSiC components were deposited on stainless steel by HVOF spraying. Cavitation erosion tests were performed and the material removal micro-mechanisms were identified by SEM of both the eroded areas and the specimens’ cross-sections. Waves’ propagation and deflection at the weak interfaces within the coatings resulted in local tensile stresses perpendicular to the interface direction that eventually led to material remova...

  1. High-Temperature Exposure Studies of HVOF-Sprayed Cr3C2-25(NiCr)/(WC-Co) Coating

    Science.gov (United States)

    Singh, Harpreet; Kaur, Manpreet; Prakash, Satya

    2016-08-01

    In this research, development of Cr3C2-25(NiCr) + 25%(WC-Co) composite coating was done and investigated. Cr3C2-25(NiCr) + 25%(WC-Co) composite powder [designated as HP2 powder] was prepared by mechanical mixing of [75Cr3C2-25(NiCr)] and [88WC-12Co] powders in the ratio of 75:25 by weight. The blended powders were used as feedstock to deposit composite coating on ASTM SA213-T22 substrate using High Velocity Oxy-Fuel (HVOF) spray process. High-temperature oxidation/corrosion behavior of the bare and coated boiler steels was investigated at 700 °C for 50 cycles in air, as well as, in Na2SO4-82%Fe2(SO4)3 molten salt environment in the laboratory. Erosion-corrosion behavior was investigated in the actual boiler environment at 700 ± 10 °C under cyclic conditions for 1500 h. The weight-change technique was used to establish the kinetics of oxidation/corrosion/erosion-corrosion. X-ray diffraction, field emission-scanning electron microscopy/energy-dispersive spectroscopy (FE-SEM/EDS), and EDS elemental mapping techniques were used to analyze the exposed samples. The uncoated boiler steel suffered from a catastrophic degradation in the form of intense spalling of the scale in all the environments. The oxidation/corrosion/erosion-corrosion resistance of the HVOF-sprayed HP2 coating was found to be better in comparison with standalone Cr3C2-25(NiCr) coating. A simultaneous formation of protective phases might have contributed the best properties to the coating.

  2. Determination of Cd, Cr and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, Lidiane Cristina; Gustinelli Arantes de Carvalho, Gabriel [NAPTISA Research Support Center “Technology and Innovation for a Sustainable Agriculture”, Center for Nuclear Energy in Agriculture, University of São Paulo, Av. Centenário 303, 13416-000, Piracicaba SP (Brazil); Santos, Dario [Federal University of São Paulo, R. Prof. Artur Riedel 275, 09972-270, Diadema SP (Brazil); Krug, Francisco José, E-mail: fjkrug@cena.usp.br [NAPTISA Research Support Center “Technology and Innovation for a Sustainable Agriculture”, Center for Nuclear Energy in Agriculture, University of São Paulo, Av. Centenário 303, 13416-000, Piracicaba SP (Brazil)

    2014-07-01

    A validated method for quantitative determination of Cd, Cr, and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy (LIBS) is presented. Laboratory samples were comminuted and homogenized by cryogenic or planetary ball milling, pressed into pellets and analyzed by LIBS. The experimental setup was designed by using a Q-switched Nd:YAG at 1064 nm with 10 Hz repetition rate, and the intensity signals from Cd II 214.441 nm, Cr II 267.716 nm and Pb II 220.353 nm emission lines were measured by using a spectrometer furnished with an intensified charge-coupled device. LIBS parameters (laser fluence, lens-to-sample distance, delay time, integration time gate, number of sites and number of laser pulses per site) were chosen after univariate experiments with a pellet of NIST SRM 695 (Trace Elements in Multi-Nutrient Fertilizer). Calibration and validation were carried out with 30 fertilizer samples from single superphosphate, triple superphosphate, monoammonium phosphate, and NPK mixtures. Good results were obtained by using 30 pulses of 50 J cm{sup −2} (750 μm spot size), 2.0 μs delay time and 5.0 μs integration time gate. No significant differences between Cd, Cr, and Pb mass fractions determined by the proposed LIBS method and by ICP OES after microwave-assisted acid digestion (AOAC 2006.03 Official Method) were found at 95% confidence level. The limits of detection of 1 mg kg{sup −1} Cd, 2 mg kg{sup −1} Cr and 15 mg kg{sup −1} Pb and the precision (coefficients of variation of results ranging from 2% to 15%) indicate that the proposed LIBS method can be recommended for the determination of these analytes in phosphate fertilizers. - Highlights: • First LIBS application for quantitative Cd, Cr and Pb determination in fertilizers. • LIBS method was validated for analysis of phosphate fertilizers pressed pellets. • LIBS sample throughput is remarkably better than already existing methods.

  3. Influence of composition and phase distribution on the oxidation behaviour of NiCoCrAlY alloys

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Arroyo, R.; Clemens, D.; Tietz, F.; Anton, R.; Quadakkers, J.; Singheiser, L. [Forschungszentrum Juelich GmbH (Germany). IWV 2

    2001-07-01

    Phase composition and distribution can strongly affect the transient oxide stages as well as the internal oxide morphology of Ni(Co)CrAlY alloys and coatings. In the present paper the influence of Co-, Cr- and Al-additions on phase composition and morphology is illustrated. Co, as well as Cr, destabilises the {gamma}'-phase and promotes the formation of the {sigma}-phase. Dilatometry is shown as an useful technique to determine phase transformations in Ni(Co)CrAlY alloys upon temperature changes. The phase distribution determines the morphology of the oxide formed during early stages of oxidation and the NiY-phase distribution. The distribution of the NiY-rich phase determines the final morphology of the internal oxidation. A coarse distribution of the NiY-phase on Ni(Co)CrAlY grain boundaries leads to a finger type internal oxidation which was found to have a detrimental effect on oxide scale adherence. (orig.)

  4. 22Cr High-Mn-N Low-Ni Economical Duplex Stainless Steels

    Institute of Scientific and Technical Information of China (English)

    JIANG Da-wei; GE Chang-sheng; ZHAO Xiang-juan; LI Jun; SHI Lu-lu; XIAO Xue-shan

    2012-01-01

    A new family of economical duplex stainless steels in which N or Mn was substituted for Ni with composi- tion of 22Cr-8.0Mn-xNi-1.0Mo-0.7Cu-0.7W-0.3N (x = 0.5 -- 2.0) have been developed by examining the micro- structure, mechanical and corrosion properties of these alloys. The results show that these alloys have a balanced ferrite-austenite relation. In addition, the alloys are free of precipitation of sigma phase and Cr-nitride when solution- treated at 750 to 1300℃ for 30 min. The yield strength, tensile strength and fracture elongation values of experi- mental alloys solution-treated at 1050 ℃ for 30 min are about 500, 750 MPa and 40.0%, respectively. Low-temper- ature impact properties can be improved distinctly with the increase of nickel content. Among the designed DSS al- loys, the alloy with Ni of 2.0% is found to be an optimum alloy with proper phase proportion, better low-tempera- ture impact properties and higher pitting corrosion resistance compared with those o~ other alloys. The mechanical and corrosion properties and lower production cost of the designed DSSs are better than those of AISI 304.

  5. Stacking fault energy measurements in solid solution strengthened Ni-Cr-Fe alloys using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Unfried-Silgado, Jimy [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil); Universidade Estadual de Campinas UNICAMP, Faculdade de Engenharia Mecanica FEM, Campinas (Brazil); Universidad Autonoma del Caribe, Grupo IMTEF, Ingenieria Mecanica, Barranquilla (Colombia); Wu, Leonardo [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil); Furlan Ferreira, Fabio [Universidade Federal do ABC, Centro de Ciencias Naturais e Humanas (CCNH), Sao Paulo (Brazil); Mario Garzon, Carlos [Universidad Nacional de Colombia, Departamento de Fisica, Bogota (Colombia); Ramirez, Antonio J, E-mail: antonio.ramirez@lnnano.org.br [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil)

    2012-12-15

    The stacking fault energy (SFE) in a set of experimental Ni-Cr-Fe alloys was determined using line profile analysis on synchrotron X-ray diffraction measurements. The methodology used here is supported by the Warren-Averbach calculations and the relationships among the stacking fault probability ({alpha}) and the mean-square microstrain (<{epsilon}{sup 2}{sub L}>). These parameters were obtained experimentally from cold-worked and annealed specimens extracted from the set of studied Ni-alloys. The obtained results show that the SFE in these alloys is strongly influenced by the kind and quantity of addition elements. Different effects due to the action of carbide-forming elements and the solid solution hardening elements on the SFE are discussed here. The simultaneous addition of Nb, Hf, and, Mo, in the studied Ni-Cr-Fe alloys have generated the stronger decreasing of the SFE. The relationships between SFE and the contributions on electronic structure from each element of additions were established.

  6. Prediction about precipitation sequence in 18Cr-8Ni steel by system free energy method

    Energy Technology Data Exchange (ETDEWEB)

    Toda, Y.; Abe, F. [National Institute for Materials Science (NIMS), Tsukuba (Japan)

    2008-07-01

    The applicability of theoretical energy analysis to the evolution of microstructures in heat-resistant steels was explored by using the system free energy method to predict the precipitation of M{sub 23}C{sub 6} (where M means metallic alloying element) carbide and {sigma} phase within grains in 18Cr-8Ni austenitic steels. The chemical free energy of Fe-CCr- Ni quaternary steel and the interfacial and elastic strain energies between austenitic ({gamma}) matrix and the M{sub 23}C{sub 6} and o phase were estimated for the system free energy of microstructures wherein coherent or incoherent M{sub 23}C{sub 6} and the incoherent {sigma} phase were precipitated within {gamma} grains. By identifying the minimum-energy path through a determination of system free energy hierarchies, the precipitation initiation curves of precipitates in Fe-0.07C-18.95Cr-9.57Ni steel for temperatures between 823-973 K were theoretically predicted. The calculated curves agreed well with experimental results for Type 304H austenitic steels; this suggests that the system free energy method is suitable for predicting the evolution of microstructures in heatresistant steels. (orig.)

  7. Influence of fatigue on the nanohardness of NiTiCr-wires

    Energy Technology Data Exchange (ETDEWEB)

    Frotscher, M. [Ruhr University, Bochum, Germany; Young, M. L. [Ruhr University, Bochum, Germany; Bei, Hongbin [ORNL; George, Easo P [ORNL; Neuking, K. [Ruhr University, Bochum, Germany; Eggeler, G. [Ruhr University, Bochum, Germany

    2009-01-01

    Testing parameters, such as rotational speed and bending radius, have a strong influence on the fatigue life of pseudoelastic NiTi shape-memory alloys during bending rotation fatigue (BRF) experiments [M. F. X. Wagner, Int. J. Mat. Res. 97 (2006), p. 1687-1696. and M. Frotscher, et al., Thermomechanical processing, microstructure and bending rotation fatigue of ultra-fine grained NiTiCr-wires, Proceedings of the International Conference for Shape Memory and Superelastic Technologies (SMST 2007), Tsukuba, Japan, ASM International, (2008), p. 149-158.]. Previous studies showed a decrease in the fatigue life for smaller bending radius (i.e. higher equivalent strain) and larger rotational speed. This observation is associated with an increase of dislocation density, the stabilization of stressinduced martensite during cycling, and an increase of the plateau stresses due to self-heating. In the present study, we examine the influence of these fatigue parameters on the nanohardness and shape recovery of pseudoelastic NiTiCr shape-memory alloy wires by nanoindentation. We show that nanoindentation is a suitable method for the characterization of fatigue-related microstructural changes, which affect the mechanical properties.

  8. Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

    Science.gov (United States)

    Bojack, A.; Zhao, L.; Morris, P. F.; Sietsma, J.

    2016-05-01

    The influence of austenitization treatment of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) on austenite formation during reheating and on the fraction of austenite retained after tempering treatment is measured and analyzed. The results show the formation of austenite in two stages. This is probably due to inhomogeneous distribution of the austenite-stabilizing elements Ni and Mn, resulting from their slow diffusion from martensite into austenite and carbide and nitride dissolution during the second, higher temperature, stage. A better homogenization of the material causes an increase in the transformation temperatures for the martensite-to-austenite transformation and a lower retained austenite fraction with less variability after tempering. Furthermore, the martensite-to-austenite transformation was found to be incomplete at the target temperature of 1223 K (950 °C), which is influenced by the previous austenitization treatment and the heating rate. The activation energy for martensite-to-austenite transformation was determined by a modified Kissinger equation to be approximately 400 and 500 kJ/mol for the first and the second stages of transformation, respectively. Both values are much higher than the activation energy found during isothermal treatment in a previous study and are believed to be effective activation energies comprising the activation energies of both mechanisms involved, i.e., nucleation and growth.

  9. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling

    Science.gov (United States)

    Chaudhary, V.; Ramanujan, R. V.

    2016-10-01

    Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100‑xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg‑1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications.

  10. Fe, Cr, Ni, Cu, Mg, Al, Ti, and S contents in plants and soil of heaps of nickel smelting works

    Energy Technology Data Exchange (ETDEWEB)

    Banasova, V.; Hajduk, J.

    1977-01-01

    The writers established the Fe, Ce, Cr, Ni, Ca, Mg, Al, Ti and S contents in the neopedon of heaps piling up from processing of nickel ore as well as in the plants: Cardaria draba, Salsola cali, Agropyrum repens, Bromus erectus, Calamagrostis epigeios, Cynodon dactylon and Matricaria inodora, growing on such heaps. Ca, Mg and S contents were found to be higher in dicotyledons and Fe, Al, Ti, Ni and Cr contents higher in monocotyledons. The analyzed dicotyledons appeared to be concentrators of Ca and S. Highest Fe, Al, Ti, Ni and Cr contents were found in individuals of the species Agropyrum repens. The neopedon as well as the plants had extraordinarily high Cr concentrations. The species Salsola cali has been found to possess an unusually higher affinity to the dump substrate after processing of nickel ore and to be a concentrator of Mg. 16 references, 1 table.

  11. Thermodynamic Modelling of Fe-Cr-Ni-Spinel Formation at the Light-Water Reactor Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kurepin, V.A.; Kulik, D.A.; Hitpold, A.; Nicolet, M

    2002-03-01

    In the light water reactors (LWR), the neutron activation and transport of corrosion products is of concern in the context of minimizing the radiation doses received by the personnel during maintenance works. A practically useful model for transport and deposition of the stainless steel corrosion products in LWR can only be based on an improved understanding of chemical processes, in particular, on the attainment of equilibrium in this hydrothermal system, which can be described by means of a thermodynamic solid-solution -aqueous-solution (SSAS) model. In this contribution, a new thermodynamic model for a Fe-Cr-Ni multi-component spinel solid solutions was developed that considers thermodynamic consequences of cation interactions in both spinel sub-Iattices. The obtained standard thermodynamic properties of two ferrite and two chromite end-members and their mixing parameters at 90 bar pressure and 290 *c temperature predict a large miscibility gap between (Fe,Ni) chromite and (Fe,Ni) ferrite phases. Together with the SUPCRT92-98 thermo- dynamic database for aqueous species, the 'spinel' thermodynamic dataset was applied to modeling oxidation of austenitic stainless steel in hydrothermal water at 290*C and 90 bar using the Gibbs energy minimization (GEM) algorithm, implemented in the GEMS-PSI code. Firstly, the equilibrium compositions of steel oxidation products were modelIed as function of oxygen fugacity .fO{sub 2} by incremental additions of O{sub 2} in H{sub 2}O-free system Cr-Fe- Ni-O. Secondly, oxidation of corrosion products in the Fe-Cr-Ni-O-H aquatic system was modelIed at different initial solid/water ratios. It is demonstrated that in the transition region from hydrogen regime to oxygen regime, the most significant changes in composition of two spinel-oxide phases (chromite and ferrite) and hematite must take place. Under more reduced conditions, the Fe-rich ferrite (magnetite) and Ni-poor chromite phases co-exist at equilibrium with a metal Ni

  12. Determination of Cr and Cd concentration adsorbed by chicken feathers; Determinacion de concentracion de Cr y Cd adsorbido por plumas de pollo

    Energy Technology Data Exchange (ETDEWEB)

    Lopez M, A.; Cuapio O, L.A.; Cardenas P, S.; Balcazar, M. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico); Jauregui, V.; Bonilla P, A. [ITA, Aguascalientes (Mexico)

    2008-07-01

    In this work the results of the samples analysis of chicken feathers are presented, used as adsorber of the heavy metals Cd and Cr present in water solutions with well-known concentrations of these metals. It was used the Neutron Activation Analysis technique (AAN), using the TRIGA Mark-III reactor of the Nuclear Center of Mexico. The obtained results they show the advantages of having a versatile installation for the analysis of this type of samples. By means of the analysis of the results, it was determined the feasibility of using chicken feathers like adsorber of these metals present in polluted waters, additionally, it was detected the presence of others polluting elements in the inputs to prepare the reference solutions as well as in the processes, so much of preparation of the feathers like of the metals adsorption. (Author)

  13. Physical and mechanical properties of the nanocomposite and combined Ti-N-Si /WC-Co-Cr and Ti-N-Si/(CR3C2)75-(NiCr)25 coatings

    OpenAIRE

    O.V. Kolisnichenko; N.A. Makhmudov; N.K. Erdybayeva; Beresnev, V. M.; G.V. Kirik; A.V. Pshyk; A.P. Shypylenko; M.V. Kaverin; M.V. Il’yashenko; A.D. Pogrebnjak; Yu.N. Tyurin; A.P.Shpak

    2009-01-01

    Two types of the combined nanocomposite coatings (Ti-N-Si /WC-Co-Cr and Ti-N-Si/ (Cr3C2Ni)75-(NiCr)25) of 160-320 μm thickness were produced using two deposition techniques: the cumulative-detonation and the vacuum-arc deposition with the high-frequency discharge. This gives the possibility (using the combined coatings) to restore the size of worn areas of the tools and demonstrate the high corrosion and wear resistance, to increase the hardness, modulus of elasticity, and plasticity index. C...

  14. Low friction coefficient coatings Ni-Cr by magnetron sputtering, DC

    Directory of Open Access Journals (Sweden)

    Morales-Hernández, Jorge

    2015-09-01

    Full Text Available Magnetron Sputter Deposition technique with DC was used for the deposition of Ni-Cr coatings on AISI 316 SS like substrate. The cathode with a nominal composition Ni-22 at% Cr was prepared by Mechanical Alloying (MA technique, with a maximum milling time of 16 hours and, with a high energy SPEX 8000 mill. The coatings were made under Argon atmosphere at room temperature with a power of 100 W at different times of growth. Chemical composition, microstructure, topography, nanohardness and wear of the coatings were evaluated using the techniques of microanalysis by energy dispersive X-ray analyzer (EDAX, X-Ray Diffraction (XRD, Atomic Force Microscopy (AFM, Nano-indentation and pin-on-Disk, respectively. After milling, was not detected contamination in the mixtures. XRD analysis revealed that the microstructure of the Ni-Cr alloy was maintained in the coatings with respect to MA powders, with some degree of recrystallization. Nanohardness values were in the order of 8.8 GPa with a Young’s modulus of 195 GPa. The adhesion of the films was evaluated according to their resistance to fracture when these were indented at different loads using Vickers microhardness. The wear test results showed a decrease in the friction coefficient with respect to the increase of thickness’ films, getting a minimum value of 0.08 with a thickness of 1 μm and which correspond with the maximum growing time.La técnica de Deposición por Chisporroteo Magnético (Magnetron Sputtering con el proceso DC, fue usado para la deposición de los recubrimientos de Ni-Cr sobre acero inoxidable AISI 316 como sustrato. El cátodo con una composición nominal Ni-22 at% Cr fue preparado por la técnica de Aleado Mecánico (AM, con un tiempo máximo de molienda de 16 horas y con un molino de alta energía tipo SPEX 8000. Las películas se realizaron bajo una atmósfera de argón a temperatura ambiente con una potencia de 100 W a diferentes tiempos de crecimiento. La composición qu

  15. Orientational domains in metalorganic chemical vapor deposited CdTe(111) film on cube-textured Ni

    International Nuclear Information System (INIS)

    CdTe thin film was grown by metal organic chemical vapor deposition on cube-textured Ni substrate. The microstructures of the CdTe film and Ni substrate were studied using transmission electron microscopy (TEM) lattice imaging in cross sectional. The orientational relationships of multiple hetereoepitaxial domains in the CdTe film were examined by TEM diffraction. The observed epitaxy is [111]CdTe//[001]Ni. The adjacent domains in CdTe film have a 30° rotation with respect to each other as inferred by the observed different diffraction patterns obtained from different zone axes. The high resolution lattice imaging shows that lamellar twins dominate within each domain. Our results are compared with CdTe(111) film epitaxially grown on Si(001) substrate by molecular beam epitaxy reported in the literature. - Highlights: ► Epitaxial CdTe film grew on textured Ni at 350 °C despite of a large lattice mismatch. ► Epitaxial relationship is CdTe(111) parallel to Ni(001). ► 30° CdTe orientation domains inferred from transmission electron microscopy patterns ► Local inclined angle between CdTe and Ni at the interface is due to vertical mismatch. ► Single crystal-like epitaxial semiconductors can be grown on low cost metal sheet

  16. Fine scale remobilisation of Fe, Mn, Co, Ni, Cu and Cd in contaminated marine sediment

    DEFF Research Database (Denmark)

    Tankere-Muller, Sophie; Zhang, Hao; Davison, William;

    2007-01-01

    to less than 0.3 μM. With both DET and DGT measurements, there were sharply defined maxima of Cu and Cd within 2 mm of the sediment water interface, consistent with their release from organic material as it is oxidised. There was a Co maximum about 5–8 mm lower than the Cu and Cd maxima, apparently...... that the localised mobilisation of metals was associated with recent diagenetic processes, rather than the depositional history. There were substantial fluxes of Cu and Cd to the overlying water. Even though there were steep gradients of Fe, Mn, Ni and Co within 1 cm of the sediment–water interface...

  17. Electron level investigation on strengthening mechanism of 23MnNiMoCr54 steel by Mo%Mo强化23MnNiMoCr54钢机理的电子层次研究

    Institute of Scientific and Technical Information of China (English)

    孙跃军; 李擎宇; 李思南; 崔润达

    2013-01-01

    利用固体与分子经验电子理论(EET),计算23MnNiMoCr54钢中温回火组织特征相的电子结构参数.根据固溶强化作用因子和界面强化系数的计算结果,从电子层次研究了Mo强化23MnNiMoCr54钢的微观机理.结果表明:对于23MnNiMoCr54钢中温回火组织,Mo主要强化了α-Fe-C结构单元,对界面强度影响不大.%Electron structure parameters of 23MnNiMoCr54 in medium temperature tempered state were calculated by employing empirical electron theory of solids and molecules (EET). Based on the calculating results of solid solution strengthening gene and interface strengthening coefficient, the strengthening mechanism of Mo on 23MnNiMoCr54 steel was investigated. The calculating results show that the main effect of Mo is to strengthen α-Fe-C unit in tempered microstructure and almost no contributions to interface strength.

  18. Expression and modulation of complement receptor 2 (CR2/CD21) in the pathophysiology of rheumatoid arthritis

    OpenAIRE

    Rozaleen Dash; Uma Kumar; Maumita Kanjilal; Nibhriti Das

    2016-01-01

    Background: The involvement of B cells, complement activation and subsequent immune complex deposition has been implicated in the pathogenesis of rheumatoid arthritis (RA). Although the reduced expression of complement receptor 2 (CR2, CD21) on the B cells of RA patients is known for long, we aimed at determining the modulation and expression of CR2 on PBMC of healthy individuals and RA patients. Methods: Sixty controls and 57 RA patients were enrolled. PBMC-CR2 transcript levels were corr...

  19. Study on Wire Material Selection in the welding of 06Cr13 Heat Exchange Tube and 06Cr19Ni10 Tube Sheet%06Cr13换热钢管与06Cr19Ni10管板焊材选择试验研究

    Institute of Scientific and Technical Information of China (English)

    张莹莹; 纪强; 王娜; 张岚

    2014-01-01

    ER316L,ER309L and ERNiCr-3 welding wires were respectively used in GTAW welding of 06Cr13 heat exchange tube and 06Cr19Ni10 tube sheet. Then the welding seams were tested by using PT, Leica microscope and Vickers hardness tester. The results show that, when using ER316L as wire material, the welding seam has no cracks ,and has the best weld organization.%使用ER316L、ER309L及ERNiCr-3焊丝对06Cr13换热钢管与06Cr19Ni10管板进行平缝GTAW管头自动焊接,通过PT、Leica显微镜和维氏硬度等方法检测,06Cr13换热钢管与06Cr19Ni10管板使用ER316L焊丝进行焊接时,焊缝没有裂纹,组织性能最优,说明试验所选焊接工艺参数是合理的,ERNiCr-3焊丝焊后试件存在裂纹,试验不合格。

  20. Thermal aging modeling and validation on the Mo containing Fe-Cr-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Busby, Jeremy T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-04-01

    Thermodynamics of intermetallic phases in Fe-rich Fe-Cr-Ni-Mo alloys is critical knowledge to understand thermal aging effect on the phase stability of Mo-containing austenitic steels, which subsequently facilitates alloy design/improvement and degradation mitigation of these materials for reactor applications. Among the intermetallic phases, Chi (χ), Laves, and Sigma (σ) are often of concern because of their tendency to cause embrittlement of the materials. The focus of this study is thermal stability of the Chi and Laves phases as they were less studied compared to the Sigma phase. Coupled with thermodynamic modeling, thermal stability of intermetallic phases in Mo containing Fe-Cr-Ni alloys was investigated at 1000, 850 and 700 C for different annealing times. The morphologies, compositions and crystal structures of the precipitates of the intermetallic phases were carefully examined by scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and transmission electron microscopy. Three key findings resulted from this study. First, the Chi phase is stable at high temperature, and with decreasing temperature it transforms into the Laves phase that is stable at low temperature. Secondly, Cr, Mo, Ni are soluble in both the Chi and Laves phases, with the solubility of Mo playing a major role in the relative stability of the intermetallic phases. Thirdly, in situ transformation from Chi phase to Laves phase was directly observed, which increased the local strain field, generated dislocations in the intermetallic phases, and altered the precipitate phase orientation relationship with the austenitic matrix. The thermodynamic models that were developed and validated were then applied to evaluating the effect of Mo on the thermal stability of intermetallic phases in type 316 and NF709 stainless steels.

  1. Production of Nanocrystalline Ni-20Cr Coatings for High-Temperature Applications

    Science.gov (United States)

    Kumar, Manoj; Singh, Harpreet; Singh, Narinder

    2014-04-01

    Presynthesized nanocrystalline Ni-20Cr powder was deposited on SA 516 and T91 boiler steels by a high-velocity oxy-fuel spraying process. Ni-20Cr powder was synthesized by the ball milling approach. The high-temperature oxidation behavior of bare and coated samples was then studied under cyclic isothermal conditions at 900 °C for 50 cycles. The kinetics of oxidation was established using weight change measurements for the bare and coated boiler steels. Uncoated and coated samples of T91 steel were exposed to the superheated zone of a power plant boiler at 750 °C under cyclic conditions for 15 cycles. Each cycle consisted of 100 h of heating followed by 1 h of cooling. Attempts were made to study the kinetics of erosion-corrosion using weight change and thickness loss data for the samples. Different characterization techniques were used to study the oxidized and eroded-corroded samples, including x-ray diffraction, scanning electron microscopy/energy-dispersive spectroscopy, and x-ray mapping analyses. The Ni-20Cr alloy powder coating was found to offer excellent oxidation resistance to the base steels and was successful in reducing the weight gain of SA 516 steel by 98.5 % and that of T91 steel by 65 %. The coating was observed to reduce the erosion-corrosion rate of T91 steel by 86 % in terms of thickness loss. This indicates that the investigated nanostructured coating can be a better choice over conventional coating for erosion-corrosion control of boiler tubes.

  2. Microstructural effects of high temperature thermal treatment in Fe--Cr--Ni austenitic stainless steels

    International Nuclear Information System (INIS)

    A study was undertaken to determine the effects of various thermal treatments on the microstructure of eight experimental stainless steel alloys. Seven of the 50-lb (23-kg) consumable--electrode vacuum--melted heats were Fe--Cr--Ni ternaries that vary in composition from 10 percent Ni--19 percent Cr to 19 percent Ni--24 percent Cr, while the eighth was a quaternary containing 3.5 wt percent Mn. High-purity starting stock and careful melting procedures produced compositions with low residual element contents e.g., (in ppM), P, 5--15; C, 40--60; S, 40--55; H, 10--35; N, 20--100; and O, 100--350. The cast ingots were extruded at 11000C to 1.5-in.-dia bar, portions of which were subsequently either forged and hot rolled to plate or swaged at room temperature to 9/32-in.-dia rod. Only portions of the swaged rod were used in the present thermal treatment study. 3/8-in. lengths of each heat were heat treated in vacuum for 1 h at each of the following temperatures: 900, 1000, 1050, 1100, 1150, 1200, and 12500C. A transverse section of each specimen was prepared for metallographic examination and etched with 50 HCl--10 HNO3 to reveal the general microstructure, and with boiling Murakami's reagent to reveal delta-ferrite. The grain size in each specimen was estimated by comparison with ASTM Standard Grain Size overlays. Additionally, DPH transverses were taken across each specimen, andthe amount of ferromagnetic phase (delta-ferrite and/or martensite) in each was determined by use of a Magne-Gage. 20 figs

  3. Fatigue Property Study of 05Cr17Ni4Cu4Nb Steel Weld Joints%05Cr17Ni4Cu4Nb钢焊接接头的疲劳性能

    Institute of Scientific and Technical Information of China (English)

    刘福广; 李振伟; 冯琳杰; 李太江; 王琦; 王彩侠; 李巍

    2013-01-01

    Fatigue property of 05Cr17Ni4Cu4Nb steel used for last stage rotor blade of steam turbine weld joints was studied by means of four-point-bending fatigue test and S-N curve was obtained, compared with parent material at the same time. Results showed that conditional fatigue limit of o5Cr17Ni4Cu4Nb steel weld joints can reach 90%of parent metal using optimized weld and post weld heat treatment process. SEM observation of fracture surface of fatigue specimen showed that the micro-defect at surface or near surface and microstructure heterogeneity are the main influence factors of 05Cr17Ni4Cu4Nb weld joints fatigue property.%采用四点弯曲疲劳试验方法,研究了05Cr17Ni4Cu4Nb汽轮机低压末级动叶片用钢焊接接头的疲劳性能,绘制了该钢焊接接头的S-N曲线,并与05Cr17Ni4Cu4Nb钢母材进行了对比。研究结果表明,采用优化的焊接、热处理工艺,05Cr17Ni4CuNb钢焊接接头的条件疲劳极限可以达到母材的90%以上。疲劳试样断口的扫描电子显微镜观察发现,焊缝表面或近表面的显微缺陷及接头的组织不均匀性是影响05Cr17Ni4Cu4Nb钢焊接接头接头疲劳性能的主要因素。

  4. Chemical and physical characterization of electrode materials of spent sealed Ni-Cd batteries.

    Science.gov (United States)

    Nogueira, C A; Margarido, F

    2007-01-01

    The present work aimed at the chemical and physical characterization of spent sealed MONO-type Ni-Cd batteries, contributing to a better definition of the recycling process of these spent products. The electrode material containing essentially nickel, cadmium and some cobalt corresponds to approximately 49% of the weight of the batteries. The remaining components are the steel parts from the external case and the supporting grids (40%) containing Fe and Ni, the electrolyte (9%) and the plastic components (2%). Elemental quantitative analysis showed that the electrodes are highly concentrated in metals. The phase identification achieved by X-ray powder diffraction combined with chemical analysis and leaching tests allowed the authors to proceed with the composition of the electrode materials as following: cathode: 28.7% metallic Ni, 53.3% Ni(OH)2, 6.8% Cd(OH)2 and 2.8% Co(OH)2; anode: 39.4% metallic Ni and 57.0% Cd(OH)2. The morphology of the electrodes was studied by microscopic techniques and two phases were observed in the electrodes: (1) a bright metallic phase constituted of small nickel grains that acts as conductor, and (2) the main hydroxide phase of the active electrodes into which the nickel grains are dispersed. The disaggregation of the electrode particles from the supporting plates was easily obtained during the dismantling procedures, indicating that a substantial percentage of the electrodes can be efficiently separated by wet sieving after shredding the spent batteries. PMID:17166709

  5. Characteristics of centrifugally cast GX25CrNiSi18-9 steel

    Directory of Open Access Journals (Sweden)

    R. Zapała

    2011-07-01

    Full Text Available The paper presents the results of microstructural examinations of the industrial heat-resistant centrifugally cast GX25CrNiSi18-9 steel characterised by increased content of Cu. The study included changes in the microstructure of base cast steel respective of the steel held at a temperature of 900 and 950°C for 48 hours. Based on the results obtained, an increase in microhardness of the examined cast steel matrix with increasing temperature was stated, which was probably caused by fine precipitates enriched in Cr, Mo, and C forming inside the matrix grains.The layer of scale formed on the tested cast steel oxidised in the atmosphere of air at 900 and 950°C was characterised by an increased tendency to degradation with increasing temperature of the conducted tests.

  6. Development of banded microstructure in 34CrNiMo6 steel

    Directory of Open Access Journals (Sweden)

    A. Nagode

    2016-07-01

    Full Text Available In this paper the development of a banded microstructure in hot-rolled 34CrNiMo6 steel which consisted of bainitic and martensitic bands is explained. The chemical compositions of the bands were measured with energy dispersive x-ray spectroscopy (EDS, which showed that the martensitic bands contained more alloying elements (Mn, Cr, Mo, Si than bainitic bands. By using Oberhoffer reagent, the segregations of phosphorus were also revealed. These phosphorus segregations coincided with the positive segregations of the alloying elements. The continuous cooling transformation (CCT diagrams of steel were calculated. They confirmed the formation of martensite in positive segregations and the formation of bainite in negative segregations.

  7. Precipitation kinetics in austenitic 18Cr-30Ni-Nb cast steel

    Directory of Open Access Journals (Sweden)

    M. Garbiak

    2008-08-01

    Full Text Available The study presents the results of investigations on the precipitation kinetics in austenitic 18%Cr-30%Ni cast steel stabilised with an addition of 1.84 wt% niobium. Phase analysis of isolates extracted from the alloy subjected to annealing within the temperature range of 600–1000oC during 10–1000 h was made. The phase constitution of the isolates mainly comprised niobium carbides of the NbC type and complex chromium carbides of the Cr23C6 type. In specimens annealed within the temperature range of 700–900oC, a high-silicon G phase was additionally identified. The highest kinetics of the precipitation process was recorded after annealing at the temperatures of 800 and 900oC.

  8. APFIM investigations on site occupancies of the ternary alloying elements Cr, Fe, and Re in NiAl

    International Nuclear Information System (INIS)

    The site occupancies of the transition metals Cr, Fe, and Re dissolved in NiAl of stoichiometric composition have been determined by atomic layer resolved atom probe field-ion microscopy (APFIM). The investigations were supported by X-ray diffraction studies to evaluate the lattice parameters. These are influenced by atomic size effects and constitutional lattice defects like Ni antistructure atoms in the Al sublattice and vacancies in the Ni sublattice. The APFIM results were compared with ALCHEMI data and calculated site preference energies published in the literature. Chromium additions to stoichiometric NiAl with 0.8 at% in solid solution exhibit a strong preference for Al sites. The lattice parameter of NiAl(Cr) solid solution is decreased. Iron atoms dissolved in higher concentrations of 5 at % in NiAl are almost equally distributed within both sublattices. They are possessing a weak preference for Al sites, which causes a lattice expansion of NiAl(Fe) solid solution. ALCHEMI results and site preference energy data show a strong site preference of Cr atoms for the Al sublattice. In contrast, iron atoms exhibit a weak site preference for Ni sites depending upon the stoichiometry of the NiAl host lattice. Re solutes in low concentrations of about 0.2 at % in NiAl possess a strong site preference for the Ni sublattice. The increase of the lattice parameter of NiAl(Re) is due to the pronounced size effect of Re atoms. For these species no ALCHEMI and site preference energy data are available in the literature

  9. Thick Graded Nanostructured Zirconia-NiCoCrAlY Composite Coatings by Plasma Spraying

    Institute of Scientific and Technical Information of China (English)

    YANG Hui; WANG Han-gong

    2004-01-01

    Thick Nanostructured PSZ-NiCoCrAlY graded TBCs were got byair plasma spraying. The results reveal the morphology and phase transformation of TBCs by means of SEM and XRD. The plasma spray process results in a characteristic layered structure consisting of lamellae, unmelted nano-particles and an inter-lamellar porosity. The test results of thermal shock show that the graded coatings have different failure behavior. The failure mode was the spallation of top coat due to thermal stress. It has been found that the lamella consists of nanoscale columnar grains parallel to the spraying direction.

  10. Basic creep models for 25Cr20NiNbN austenitic stainless steels

    OpenAIRE

    Sandström, Rolf; Farooq, Muhammad; Zurek, Joanna

    2013-01-01

    Basic models for solid solution and precipitation hardening during creep are presented for the austenitic stainless steels 25Cr20NiNbN (TP310HNbN, HR3C, DMV310N). The solid solution hardening is a result of the formation of Cottrell clouds of solutes around the dislocations. In addition to slowing down the creep, the solutes increase the activation energy for creep. The increase in activation energy corresponds to the maximum binding energy between the solutes and the dislocations. The format...

  11. A study of corrosion electrochemical properties of martensite-austenite steel Cr15Ni6Mo

    Energy Technology Data Exchange (ETDEWEB)

    Cihal, V.; Hubackova, J.; Kubelka, J.; Mezanec, K.

    1985-11-01

    The steel Cr15Ni6Mo (UHB 119) exhibits a very satisfactory corrosion resistance. However, its superior passivating ability depends on the heat treatment method used. The use of two-step tempering leads primarily to an improved resistance to reactivation and optimum properties are achieved when the basic matrix contains about 40% stable austenite in fine form. This structural state requires the use of tempering temperatures from 625 to 650/sup 0/C in Step 1, and 525/sup 0/C in Step 2 of tempering.

  12. Microstructure and pitting corrosion of 13CrNiMo weld metals

    International Nuclear Information System (INIS)

    Cyclic potentiodynamic measurements and scanning electron microscopy were used to analyze susceptibility to pitting corrosion of 13CrNiMo weld metals. In order to carry out a critical assessment of the influence of microstructural factors on localized corrosion, different heat treatments were applied to the alloys under investigation. Volume fractions of austenite in tempered conditions as well as the amount and size of precipitated carbides strongly affect pitting resistance. Characteristic potentials (pitting potential and repassivation potential) increase according to the retained austenite content. Results can be discussed in terms of a model that describes the structural refinement resulting from a double-tempering procedure

  13. Corrosion of high purity Fe-Cr-Ni alloys in 13 N boiling nitric acid

    International Nuclear Information System (INIS)

    Corrosion in boiling nitric acid was investigated for high purity Fe-18%Cr-12%Ni alloys and type 304L stainless steels (SS). Owing to very low impurity concentration, the solution treated high purity alloys show almost no intergranular corrosion while the type 304L SS show severe intergranular corrosion. Both in the high purity alloys and type 304L SS, aging treatments ranging from 873 K to 1073 K for 1 h enhance intergranular corrosion. During the aging treatments, impurities should be segregated to the grain boundaries. The corrosion behaviors were discussed from a standpoint of impurity segregation to grain boundaries. This study is of importance for purex reprocessing of spent fuels

  14. Surface stability and conductivity of a high Cr and Ni austenitic stainless steel plates for PEMFC

    Institute of Scientific and Technical Information of China (English)

    TIAN Rujin; SUN Juncai; WANG Jianli

    2006-01-01

    In order to use stainless steel as bipolar plate for PEMFC, electrochemical behavior of a high Cr and Ni austenitic stainless steel was studied in the solutions containing different concentration of H2SO4 and 2 mg·L-1 F-, and interfacial contact resistance was measured after corrosion tests. The experimental results show that the passive current density lowers with decreasing the concentration of H2SO4. The interfacial contact resistance between carbon paper and passive film formed in the simulated PEMFC environment is higher than the goal of bipolar plate for PEMFC. Surface conductivity should be further reduced by surface modification.

  15. Gaseous carburising of self-passivating Fe–Cr-Ni alloys in acetylene-hydrogen mixtures

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Hummelshøj, Thomas Strabo; Somers, Marcel A. J.

    2011-01-01

    Gaseous carburising of self-passivating Fe–Cr–Ni alloys in acetylene–hydrogen was investigated for temperatures up to 823 K. Acetylene–hydrogen gas mixtures allow both the activation of the surface and the subsequent carburising at a high and adjustable carburising potential. For relatively low t...... temperatures, carbon stabilised expanded austenite develops, which has high hardness, while retaining the corrosion performance of the untreated alloy; for relatively high temperatures, Cr based carbides develop, and eventually, the material deteriorates by metal dusting corrosion....

  16. Transformation Behavior and Microstructure in a 40Cr2Ni2MoV Cast Steel

    Institute of Scientific and Technical Information of China (English)

    Cheng Liu; Zhenbo Zhao; Sanjiwan. D. Bhole1; Derek O. Northwood

    2004-01-01

    The transformation behavior of a 40Cr2Ni2MoV cast steel manufactured by electroslag remelting (ESR) has been investigated. Compared to a forged steel, the incubation periods for both the pearlite and bainite transformations are shorter, but the transformation times are longer. The austenite is easier to transform into martensite. Optical microscopy and TEM indicated that there were variations in microstructure during the super-cooled austenite transformation. This is attributed to an inhomogeneous austenite, resulting from the segregation of elements during the ESR solidification.

  17. Preparation and characterization of LPPS NiCoCrAlYTa coatings for gas turbine engine

    Institute of Scientific and Technical Information of China (English)

    洪瑞江; 周克崧; 王德政; 朱晖朝; 邝子奇

    2001-01-01

    NiCoCrAlYTa coatings have been deposited onto an aircraft gas turbine engine blade using a LPPS unit equipped with a computerized robot. Optimal processing conditions, including spray parameters, the trajectory of the robot, and the synchronized movements between the torch and the blade, have been developed for superior coating properties. Transferred-arc treatment, providing a preheating and a cleaning of the substrate surface, enhances the adherence of the coatings to the substrate. The resulting LPPS coatings show dense and uniform characteristics with ideal hardness, and good corrosion resistance to cycle oxidation.

  18. TEM and SNMS studies of protective alumina scales on NiCrAlY-alloys.

    Science.gov (United States)

    Clemens, D; Vosberg, V; Hobbs, W; Breuer, U; Quadakkers, W J; Nickel, H

    1996-06-01

    The effect of Si addition on the oxidation behaviour of NiCrAlY alloys in the temperature range 950 bis 1100 degrees C has been investigated. During isothermal oxidation oxide growth rates were practically independent of the Si-content. However during cyclic oxidation Si additions were beneficial. Si additions of 1-2(m)/(0) appeared to shift the onset for spallation to longer times. It was found that Si stabilizes the beta-phase and probably it suppresses the formation of metastable Al(2)O(3) modifications. PMID:15045347

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

    OpenAIRE

    Gajewski, M; J. Kasińska

    2012-01-01

    This paper presents the results of Cr - Ni 18/9 austenitic cast steel modifications by mischmetal. The study was conducted on industrial melts. Cast steel was melted in an electric induction furnace with a capacity of 2000 kg and a basic lining crucible. .The mischmetal was introduced into the ladle during tapping of the cast steel from the furnace. The effectiveness of modification was examined with the carbon content of 0.1% and the presence of δ ferrite in the structure of cast steel stabi...

  20. Radiation effect on martensitic hardenable steel 03Cr10Ni--10Mo(TiAl)

    International Nuclear Information System (INIS)

    Radiation reduces notch toughness, increases strength characteristics and reduces plasticity. The chemical composition of 03Cr10Ni10Mo2 steel, mainly the effect of carbon, silicon and titanium cause changes in the radiation stability of various melts. The melt no.2 showed better notch toughness than the no.1. The regeneration annealing of irradiated samples showed the possibility of the regeneration of radiation damage. The strength characteristics are reduced, plasticity is increased. The resulting radiation hardening in the melt no.1 is also reduced for both irradiation temperatures (124 and 350 degC). (B.S.)

  1. Nitriding of a high entropy FeNiMnAlCr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Fanling; Baker, Ian, E-mail: Ian.Baker@dartmouth.edu

    2015-10-05

    Highlights: • Surface of HEA was hardened due to the formation of AlN. • Nitridation largely removed Al from alloy resulting in a single-phase f.c.c. matrix. • Nitriding at lower temperatures resulted in greater hardening. • The addition of Cr led to an increased depth of the internal precipitation of AlN. • The presence of Cr led to greater hardening due to finer AlN particles. - Abstract: The as-cast, two-phase, f.c.c. + B2, lamellar-structured, high-entropy alloy Fe{sub 28.2}Ni{sub 18.8}Mn{sub 32.9}Al{sub 14.1}Cr{sub 6} was annealed in pure nitrogen at either 800 °C or 1000 °C for 100 h in order to harden the surface by nitridation. Similar nitriding treatments were performed on a comparably-structured, four-component alloy Fe{sub 30}Ni{sub 20}Mn{sub 35}Al{sub 15} for comparison. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to analyze the resulting microstructures and phase compositions. AlN formation near the surface completely depleted the matrix of Al resulting in a f.c.c. matrix containing AlN particles, while a two-phase lamellae structure remained in the center of the specimens. Nevertheless, the AlN-containing region exhibited a higher hardness than the AlN-free area. Interestingly, the presence of Cr led to much more rapid diffusion of nitrogen into the material.

  2. Percentage of toxic trace elements; Pb, Cr and Cd in certain plastic toys, Isfahan City

    Directory of Open Access Journals (Sweden)

    F Kavehzadeh

    2006-04-01

    Full Text Available Introduction: Recent investigations have detected the presence of significant levels of heavy metals (chromium, lead and cadmium in toys and other PVC products manufactured for children. In some countries, addition of compounds containing toxic metals to toys are limited or prohibited. Methods: To evaluate the safety of some of the plastic toys in the city of Isfahan with respect to toxic trace metals, pb, cr and cd, 75 samples of three types of toys were collected from the toy shop’s and were digested with acid with the two methods ISIRI and ASTM. The heavy metals were determined using atomic absorption spectrophotometer. Variance analysis and T-test were used for data analysis. Results: The result of the study showed that the products tested contained lead, chromium and cadmium and the highest and lowest concentration were related to Pb and Cd, respectively. The statistical analysis of the samples showed that there are no significant differences between ASTM and ISIRI digestion methods. The study revealed that none of the heavy metals in the toy samples exceeded the recommended standard levels. Highest average concentration of Pb and Cd were related to toys with green color and the highest Cr concentration was related to yellow toys in this study. Conclusion: Extensive studies are required to evaluate the quality of the toys being used by children and the toxic trace elements should be eliminated from the plastic materials used for making toys.

  3. Effect of sulphate-reducing bacteria on the electrochemical impedance spectroscopy characteristics of 1Cr18Ni9Ti

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The electrochemical characteristics of 1Cr18Ni9Ti in sulphate-reducing bacteria (SRB) solutions and the biofilm of SRB on the surface of the 1Cr18Ni9Ti electrode were studied by electrochemical, microbiological, and surface analysis methods. Electrochemical impedance spectroscopy (EIS) of 1Cr18Ni9Ti was measured in the solutions with and without SRB at the culture time of 2,4, 8 d, respectively. The measurement used two test methods, the nonimmersion electrode method and the immersion electrode method. It was found that the polarization resistance (Rp) of 1Cr18Ni9Ti in the solutions without SRB is the greatest for each test method. When using the nonimmersion electrode method, Rp shifts negatively at first and then positively, and the time constant is only one. Although using the immersion electrode method, the Rp shifts positively at first and then negatively, and the time constant also changes when the biofilm forms. The biofilm observed through SEM is with pores. It was demonstrated that SRB has accelerated corrosion action on 1Cr18Ni9Ti. The protection effect of the biofilm on the electrode depends on the compact degree of the film.

  4. A feasibility study of a diffusion barrier between Ni-Cr-Al coatings and nickel-based eutectic alloys

    Science.gov (United States)

    Young, S. G.; Zellars, G. R.

    1978-01-01

    Coating systems have been proposed for potential use on eutectic alloy components in high-temperature gas turbine engines. In a study to prevent the deterioration of such systems by diffusion, a tungsten sheet 25 microns thick was placed between eutectic alloys and an Ni-Cr-Al layer. Layered test specimens were aged at 1100 C for as long as 500 h. Without the tungsten barrier the delta phase of the eutectic deteriorated by diffusion of niobium into the Ni-Cr-Al. Insertion of the tungsten barrier stopped the diffusion of niobium from the delta phase. Chromium diffusion from the Ni-Cr-Al into the gamma/gamma-prime phase of the eutectic was greatly reduced by the barrier. However, the barrier thickness decreased with time, and tungsten diffused into both the Ni-Cr-Al and the eutectic. When the delta platelets were aligned parallel rather than perpendicular to the Ni-Cr-Al layer, diffusion into the eutectic was reduced.

  5. The experiments for mechanical properties of 20Cr2Ni4 steel and the coefficient definition of constitutive equation

    Science.gov (United States)

    Pang, L.; Liu, G. C.; Lu, J. P.

    2015-12-01

    The 20Cr2Ni4 alloy steel has the properties of high strength, toughness and hardness. It is used in large cross-section carburized parts, such as gears, shafts and components which are required high strength and good toughness. In order to study the static mechanical properties and dynamic mechanical properties of 20Cr2Ni4 steel, the static compression experiment and the Hopkinson Pressure Bar test are conducted. The stress-strain relationship within the scope of 25∼400°C is obtained by experiments, and softening effect of strain rate and strengthening effect of temperature is comprehensively analyzed. The paper has a more comprehensive understanding on mechanical response of 20Cr2Ni4 steel within the scope of 25∼400°C. Based on the experiment data the parameters in Johnson-Cook constitutive equation of 20Cr2Ni4 have been gotten. The research results of this paper lay a foundation for the further applications of 20Cr2Ni4 steel.

  6. Biosorption of Cr (VI), Cr (III), Pb (II) and Cd (II) from aqueous solutions by Sargassum wightii and Caulerpa racemosa algal biomass

    Science.gov (United States)

    Tamilselvan, Narayanaswamy; Saurav, Kumar; Kannabiran, Krishnan

    2012-03-01

    Heavy metal pollution is one of the most important environmental problems today. Biosorption is an innovative technology that employs biological materials to accumulate heavy metals from waste water through metabolic process or physicochemical pathways of uptake. Even though several physical and chemical methods are available for removal of heavy metals, currently many biological materials such as bacteria, algae, yeasts and fungi have been widely used due to their good performance, low cost and large quantity of availability. The aim of the present study is to explore the biosorption of toxic heavy metals, Cr(VI), Cr(III), Pb(II) and Cd(II) by algal biomass obtained from algae Sargassum wightii (brown) and Caulerpa racemosa (green). Biosorption of algal biomass was found to be biomass concentration- and pH-dependent, while the maximal biosorption was found at pH 5.0 and with the metal concentration of 100 mg L-1. S. wightii showed the maximal metal biosorption at the biomass concentration of 25 g L-1, followed by C. racemosa with the maximal biosorption at 30 g L-1. S. wightii showed 78% biosorption of Cr(VI), Cr(III), Pb(II) and Cd(II) ions. C. racemosa exhibited 85% biosorption of Cd(II) and Cr(VI), and 50% biosorption of Cr(III) and Pb(II). The results of our study suggest that seaweed biomass can be used efficiently for biosorption of heavy metals.

  7. Mechanical Properties of DS NiAl/Cr(Mo) Alloys with Low Addition of Hf for High-temperature Applications

    Institute of Scientific and Technical Information of China (English)

    Xinghao DU; Jianting GUO

    2005-01-01

    A multiphase NiAl-28Cr-5.85Mo-0.15Hf alloy, which was directionally solidified (DS) in an Al2O3-SiO2 mold by standard Bridgman method and then underwent prolonged solution and aging treatment was prepared. The microstructure, tensile properties as well as tensile creep of the heat-treated alloy at different temperatures were studied. The alloy was composed of NiAl, Cr(Mo) and Hf-rich phase and small amount of fine Heusler phase (Ni2AlHf). Although the present alloy exhibited high tensile strength at Iow temperature, it was weaker than that of system with high content Hf but still stronger than that of many NiAl-based alloys at high temperatures. The fracture toughness is lower than that of DS NiAl-28Cr-6Mo alloy. Nevertheless, advantageous effects on the mechanical properties, i.e.the decrease in brittle-to-ductile transition temperature (BDTT) were obtained for the Iow content of Hf. The obtained creep curves exhibit conventional shape: a short primary creep and long accelerated creep stages. The rupture properties of the heat-treated alloy follow the Monkman-Grant relationship, which exhibits similar creep behavior to that of NiAl/Cr(Mo) system with high Hf content.

  8. Cr17Ni2钢焊接接头抗刀状腐蚀性能的研究%Study on the Character of Cr17Ni2 Steel Resisting Knife-line Attack

    Institute of Scientific and Technical Information of China (English)

    刘海侠; 薛锦

    2001-01-01

    采用二次稳定化退火处理,解决了Cr17Ni2钢异质焊接接头刀状腐蚀的问题。提高了用Cr17Ni2钢制造的焊接叶轮的使用寿命,取得了明显的经济效益。%The measure of twice stable annealing process is discussed.The problem of the knife-line attack of welded joint is soluted,the life of welding impeller made of Cr17Ni2 steel is prolonged and it gets evident economical benefit.

  9. 真空热处理对NiCrAlY涂层/钛合金基体体系的影响%Effect of Vacuum Heat Treatment on NiCrAlY Coating/Titanium Alloy Substrate System

    Institute of Scientific and Technical Information of China (English)

    彭小敏; 夏长清; 戴晓元; 马科

    2008-01-01

    采用电弧离子镀(AIP)技术在耐热钛合金(近TC6)基体表面沉积制备NiCrAIY涂层.通过OM、SEM与EDS、XRD分析研究不同真空热处理制度对NiCrAlY涂层/钛合金基体体系的影响.结果表明:经650℃真空热处理后,NiCrAlY涂层中开始有γ'-Ni3Al相析出,750℃时含量增加,870℃时含量明显减少;从650℃开始,NiCrAlY涂层/钛合金基体开始发生界面反应,随着温度的升高,界面分层并加厚同时出现裂纹,在870℃下,NiCrAlY涂层,钛合金基体界面由外至内出现Ni3(Al,Ti)、TiNi和Ti2Ni中间化合物层;在750℃下,主要发生了Ni、Ti元素的扩散,Cr元素在870℃开始发生扩散.当温度升高到950℃时,由于Ni、Ti元素大量互扩散导致宏观疏空带出现,同时在基体和界面反应层交界处出现裂纹,这些都将引起涂层的退化失效.

  10. Effects of cerium and manganese on corrosion of Fe–Cr and Fe–Cr–Ni alloys in Ar–20CO2 gas at 818 °C

    International Nuclear Information System (INIS)

    Highlights: •CO2 gas is more corrosive than dry air for Fe–Cr and Fe–Cr–Ni alloys at 818 °C. •Chromia scale grows faster in CO2 than in air. •Cerium has no significant effect on reducing oxidation rate of the alloys in CO2. •Manganese significantly improves oxidation resistance of Fe–20Cr and Fe–20Cr–20Ni alloys in CO2. -- Abstract: Model alloys Fe–9Cr, Fe–20Cr and Fe–20Cr–20Ni (wt.%) with Ce (0.05%, 0.1%) or Mn (1%, 2%) were exposed to Ar–20CO2 gas at 818 °C. Scales on Fe–9Cr alloys consisted of FeO and FeCr2O4, Fe–20Cr–(Ce) alloys formed only Cr2O3, and Fe–20Cr–(Mn) alloys formed Cr2O3 and MnCr2O4. All Fe–20Cr–20Ni alloys formed Fe3O4, FeCr2O4 and FeNi3. Cerium additions had little effects, but additions of 2% Mn significantly improved oxidation resistance of Fe–20Cr and Fe–20Cr–20Ni alloys. Most alloys also carburized. All alloys developed protective chromium-rich oxide scales in air. Different behavior in the two gases is attributed to faster Cr2O3 scaling rates induced by CO2

  11. Levels Of Heavy Metals (Hg, Pb, Cd, And Cr) In Tissues Of Trachurus Trachurus

    OpenAIRE

    Enkeleda Ozuni; Luljeta Dhaskali; Jetmira Abeshi; Doriana Beqiraj

    2012-01-01

    The study was carried out to monitor the concentration level of mercury, lead, cadmium and chrome in different tissues of Trachurus trachurus (Horse mackerel). The concentration level of heavy metals was measured by using atomic absorption spectrophotometer (AAS). Concentrations of heavy metals in muscle tissue and liver of this animal ranged as follows: Hg 0.032-0.106; Cd nd-0.067 mg/kg wet weight; Pb and Cr resulted always below the detection level (nd) in all tissue samples. According to t...

  12. Deposition and Oxidation of Oxide-Dispersed CoNiCrAlY Bondcoats

    Science.gov (United States)

    Okada, Mitsutoshi; Vassen, Robert; Karger, Matthias; Sebold, Doris; Mack, Daniel; Jarligo, Maria Ophelia; Bozza, Francesco

    2014-01-01

    CoNiCrAlY powder and nano-size alumina powder were milled by a high-energy-attrition ball-mill, and an oxide-dispersed powder was produced with a mixed structure of metal and alumina in each particle. The oxide-dispersed bond coat powder was deposited by HVOF. Pores, however, were observed in the coating since the alumina was deposited without sufficient melting. Isothermal oxidation tests were carried out for the bond coat specimens at a temperature of 1373 K up to 1000 h in air. As a result, oxidation proceeded inside the coating, since oxygen penetrated through pores formed in the dispersed alumina. However, the authors find that another deposition using higher power levels led to a bond coat without pores. A commercially available oxide-dispersed CoNiCrAlY powder was also deposited by HVOF and VPS, and isothermal oxidation tests were performed. The analysis clarifies that the HVOF bond coat exhibited the thinnest thermally grown oxide than those of the VPS bond coat and conventional metallic bond coat. Furnace cycling tests were conducted using the specimens with an additional ceramic thermal-barrier coating. The specimen with the bond coat sprayed by VPS using commercial oxide-dispersed powder showed almost same number of cycles to delamination compared with the specimen with the conventional metal bond coat.

  13. Degradation of a TBC with HVOF-CoNiCrAlY Bond Coat

    Science.gov (United States)

    Chen, Weijie R.

    2014-06-01

    Thermal barrier coatings (TBCs) provide both thermal insulation and oxidation and corrosion protection to the substrate metal, and their durability is influenced by delamination near the interface between the ceramic topcoat and the metallic bond coat, where a layer of thermally grown oxide (TGO) forms during service exposure. In the present work, the degradation process of a TBC with an air-plasma-spray ZrO2-8 wt.%Y2O3 topcoat and a high-velocity oxy-fuel CoNiCrAlY bond coat was studied, in terms of TGO growth kinetics and aluminum depletion in the bond coat, as well as cracking behavior. The results show that the TGO growth kinetics can be described by a transient oxidation stage with δ3 = k 1 t followed by a steady-state oxidation stage with δ2 = c + k 2 t. Significant aluminum depletion was observed in the bond coat after extended thermal exposure; however, chemical failure of the bond coat did not occur even after the aluminum content near the TGO/CoNiCrAlY interface decreased to 4.5 at.%. A power-law relationship between the maximum crack length in the TBC and the TGO thickness was observed, which may serve as the basis for TBC life prediction.

  14. Selective laser melting of Fe-Ni-Cr layer on AISI H13 tool steel

    Institute of Scientific and Technical Information of China (English)

    Byeong-Don JOO; Jeong-Hwan JANG; Jae-Ho LEE; Young-Myung SON; Young-Hoon MOON

    2009-01-01

    An attempt to fabricate Fe-Ni-Cr coating on AISI H13 tool steel was performed with selective laser melting. Fe-Ni-Cr coating was produced by experimental facilities consisting of a 200 W fiber laser which can be focused to 80 μm and atmospheric chamber which can control atmospheric pressure with N2 or Ar. Coating layer was fabricated with various process parameters such as laser power, scan rate and fill spacing. Surface quality and coating thickness were measured and analyzed. Three different surface patterns, such as typeⅠ, typeⅡand type Ⅲ, are shown with various test conditions and smooth regular pattern is obtained under the conditions as 10 μm of fill spacing, 50-350 mm/s of scan rate and 40 μm of fill spacing, 10-150 mm/s of scan rate. The maximum coating thickness is increased with power elevation or scan rate drop, and average thickness of 10 μm fill spacing is lower than that of 40 μm fill spacing.

  15. Recrystallization Behavior of CoCrCuFeNi High-Entropy Alloy

    Science.gov (United States)

    Park, Nokeun; Watanabe, Ikuto; Terada, Daisuke; Yokoyama, Yoshihiko; Liaw, Peter K.; Tsuji, Nobuhiro

    2015-04-01

    We investigated the recrystallization behavior of a cold-rolled CoCrCuFeNi high-entropy alloy (HEA). Two different face-centered cubic phases having different chemical compositions and lattice constants in the as-cast specimen have different chemical compositions: One phase was the Cu-lean matrix and the other was the Cu-rich second phase. The second phase remained even after a heat treatment at 1373 K (1100 °C) and Cu enriched more in the Cu-rich second phase. The calculated mixing enthalpies of both Cu-lean and Cu-rich phases in the as-cast and heat-treated specimens explained that Cu partitioning during the heat treatment decreased the mixing enthalpy in both phases. In the specimens 90 pct cold rolled and annealed at 923 K, 973 K, and 1073 K (650 °C, 700 °C, and 800 °C), recrystallization proceeded with increasing the annealing temperature, and ultrafine recrystallized grains with grain sizes around 1 μm could be obtained. The microhardness tended to decrease with increasing the fraction recrystallized, but it was found that the microhardness values of partially recrystallized specimens were much higher than those expected by a simple rule of mixture between the initial and cold-rolled specimens. The reason for the higher hardness was discussed based on the ultrafine grain size, sluggish diffusion expected in HEAs, and two-phase structure in the CoCrCuFeNi alloy.

  16. Efectos gammágenos del cobre en los aceros inoxidables 18Cr8Ni

    Directory of Open Access Journals (Sweden)

    Botella, J.

    1997-10-01

    Full Text Available From a series of 22 typical 18Cr8Ni stainless steel 40 kg ingots, with copper variable concentrations from 0.6 to 3.0 weight %, δ-ferrite is measured with a ferrite-meter device, calculating a nickel equivalent of 0.27 for copper. Some differences between the 8-ferrite and that on calculated by DeLong -excluding the copper γ-gene action- have been found because of different solidification and cooling regimes in ingot and weld cases.

    A partir de una serie de 22 lingotes de 40 kg de aceros inoxidables típicos 18Cr8Ni, con concentraciones variables de cobre entre 0,6 y 3,0 % en masa, se mide la ferrita δ mediante un medidor de ferrita y se deduce para el cobre un equivalente en níquel de 0,27, a la vez que se establecen ciertas diferencias entre los contenidos de ferrita δ medida y la deducida según DeLong -excluida la acción gammágena del cobre- por el hecho de solidificar en lingotes en vez de la típica solidificación de soldaduras.

  17. Metallographic etching and microstructure characterization of NiCrMoV rotor steels for nuclear power

    Institute of Scientific and Technical Information of China (English)

    Peng Liu; Feng-gui Lu; Xia Liu; Yu-lai Gao

    2013-01-01

    The grain size of prior austenite has a distinct influence on the microstructure and final mechanical properties of steels. Thus, it is significant to clearly reveal the grain boundaries and therefore to precisely characterize the grain size of prior austenite. For NiCrMoV rotor steels quenched and tempered at high temperature, it is really diffi cult to display the grain boundaries of prior austenite clearly, which limits a further study on the correlation between the properties and the corresponding microstructure. In this paper, an eff ective etchant was put forward and further optimized. Experimental results indicated that this agent was eff ective to show the details of grain boundaries, which help analyze fatigue crack details along the propagation path. The optimized corrosion agent is successful to observe the microstructure characteristics and expected to help analyze the eff ect of microstructure for a further study on the mechanical properties of NiCrMoV rotor steels used in the field of nuclear power.

  18. Intergranular diffusion and embrittlement of a Ni-16Mo-7Cr alloy in Te vapor environment

    Science.gov (United States)

    Cheng, Hongwei; Li, Zhijun; Leng, Bin; Zhang, Wenzhu; Han, Fenfen; Jia, Yanyan; Zhou, Xingtai

    2015-12-01

    Nickel and some nickel-base alloys are extremely sensitive to intergranular embrittlement and tellurium (Te) enhanced cracking, which should be concerned during their serving in molten salt reactors. Here, a systematic study about the effects of its temperature on the reaction products at its surface, the intergranular diffusion of Te in its body and its embrittlement for a Ni-16Mo-7Cr alloy contacting Te is reported. For exposed to Te vapor at high temperature (823-1073 K), the reaction products formed on the surface of the alloy were Ni3Te2, CrTe, and MoTe2, and the most serious embrittlement was observed at 1073 K. The kinetic measurement in terms of Te penetration depth in the alloy samples gives an activation energy of 204 kJ/mol. Electron probe microanalysis confirmed the local enrichment of Te at grain boundaries. And clearly, the embrittlement was results from the intergranular diffusion and segregation of element Te.

  19. Microstructural Features Affecting Tempering Behavior of 16Cr-5Ni Supermartensitic Steel

    Science.gov (United States)

    De Sanctis, Massimo; Lovicu, Gianfranco; Valentini, Renzo; Dimatteo, Antonella; Ishak, Randa; Migliaccio, Umberto; Montanari, Roberto; Pietrangeli, Emanuele

    2015-05-01

    In industrial production processes, the respect of hardness and UTS maximum values of 16Cr5Ni steel is of utmost importance and a careful control of chemical composition and thermo-mechanical treatments is a common practice. Nevertheless, some scatter of properties is often observed with consequent rejection of final components. To better understand the role played by different factors, two heats of 16Cr-5Ni supermartensitic stainless steels with very close chemical compositions but different thermal behavior during tempering have been studied by means of TEM observations, X-ray diffraction measurements, dilatometry, and thermo-mechanical simulations. It has been found that Ms-Mf temperature range can extend below the room temperature and the relative amount of retained austenite in as-quenched conditions plays a significant role in determining the thermal behavior. When present, the γ-phase increases the amount of reversed austenite formed during tempering and accelerates the process kinetics of martensite recovery. Moreover, increasing amounts of retained austenite after quenching lower the critical temperature for austenite destabilization and influence the optimum temperature-time combination to be adopted for controlling final mechanical properties. In the studied cases, the very close chemical composition of the heats was not a sufficient condition to guarantee the same as-quenched structure in terms of retained austenite amount. This was proven to be related to solute segregation effects during solidification of original heats.

  20. Complement receptors type 1 (CR1, CD35) and 2 (CR2, CD21) cooperate in the binding of hydrolyzed complement factor 3 (C3i) to human B lymphocytes

    DEFF Research Database (Denmark)

    Leslie, Robert Graham Quinton; Prodinger, Wolfgang Maria; Nielsen, Claus Henrik

    2003-01-01

    The C3b-binding receptor, CR1/CD35, supports CR2/CD21-mediated activation of complement by human B lymphocytes, possibly by associating with CR2 to promote or stabilize the binding of hydrolyzed C3 (C3i), the primary component of the AP convertase, C3i-Bb. To evaluate this hypothesis, we examined...... the uptake kinetics and binding equilibria for C3i dimer interaction with human blood cells in the absence and presence of CR1- and CR2-blocking mAb. C3i displayed dual uptake kinetics to B lymphocytes, comprising of rapid binding to CR1 and slower binding to CR2. The forward rate constants (k(1)) for CR1...... and CR2, operating independently, differed ca. 9-fold (k(1)=193+/-9.4 and 22.2+/-6.0 x 10(3) M(-1)s(-1), respectively). Equilibrium binding of C3i to B lymphocytes was also complex, varying in strength by ca. 13-fold over the C3i concentration range examined. The maximum association constant (K(a, max...

  1. Carburized Bearing Steel 20Cr2Ni4A Melting with EAF%电弧炉冶炼20Cr2Ni4A渗碳轴承钢

    Institute of Scientific and Technical Information of China (English)

    吴耀光

    2001-01-01

    开发了用10t-EAF熔炼20Cr2Ni4A渗碳轴承钢的工艺过程.结果表明,在合理的试验条件下,能获得电解杂质总量合格的产品,因此,单一电弧炉冶炼是可行的.%The development of the carburized bearing steel 20Cr2Ni4A with 10 t EAF, was introduced. The results show that the fiuishing product, with and lower inclusion content, was producted by the single Electro ARC Furnace.

  2. Ni3Al基合金IC6的NiCrAlY(Si)包覆型涂层研究%A Study on NiCrAlY(Si) Overlay Coating on a Ni3Al-base Alloy IC6

    Institute of Scientific and Technical Information of China (English)

    韩雅芳; 纪燕玲; 廖鸿

    2000-01-01

    研究了磁控溅射NiCrAlY(Si)包覆型涂层对Ni3Al基合金IC6的抗氧化性能及力学性能的影响,同时也研究了该涂层的微观组织及其稳定性.结果表明,研制的NiCrAlY(Si)物理沉积包覆型涂层是适合于IC6合金及其使用条件的防护涂层.

  3. 钛合金表面激光熔覆NiCrBSi(Ti)-TiC涂层%Study on laser cladding of NiCrBSi (Ti)-TiC metal-ceramiccomposite coatings on titanium alloy

    Institute of Scientific and Technical Information of China (English)

    孙荣禄; 郭立新; 董尚利; 杨德庄

    2001-01-01

    在TC4合金表面进行了激光熔覆NiCrBSi-TiC,Ti-TiC金属陶瓷复合涂层的试验,对涂层的组织和显微硬度进行了分析和测试.结果表明,NiCrBSi-TiC涂层的组织是在初晶γ-Ni和γ-Ni,Ni3B,M23(CB)6,CrB多元共晶的基底上均匀地分布着TiC颗粒,在激光熔覆过程中TiC颗粒只是边缘发生了溶解或熔化;在Ti-TiC涂层中,TiC颗粒全部溶解或熔化,冷却时以枝晶形式重新析出.NiCrBSi-TiC涂层的显微硬度(HV900~1100)明显高于Ti-TiC的涂层的显微硬度(HV500~700).

  4. Prediction Model of High Temperature Rupture Strength of 00Cr18Ni10N Steel%00Cr18Ni10N钢高温持久强度的预测与验证

    Institute of Scientific and Technical Information of China (English)

    杨旭; 王正品; 要玉宏; 刘江南

    2012-01-01

    The high temperature rupture strength of 00Crl8Nil0N stainless steel is studied, The mathematical model of relation between the rupture strength at given temperature and the high temperature tensile strength of 00Crl8Ni10N steel is established by means of total differential and state function on the basis of Larson - Miller equation. The test data indicate: The rupture strength of 00Cr18Ni10N steel at 700 ℃ lasting 200 h calculated by the model conforms to the tested value. The relative error between them is 0. 6%.%研究了00Cr18Ni10N钢的高温持久强度.在Larson-Miller方程基础上,利用全微分和状态函数特征,建立了00Cr18Ni10N钢在给定温度条件下持久强度与高温抗拉强度之间关系的数学模型.通过试验结果表明,利用该数学理论模型预测00Cr18Ni10N钢在700℃,持久拉伸200 h理论与实测持久强度值相符,相对误差为0.6%.

  5. Localized ageing in the heat affected zone of welded X5CrNiCuNbl6-4 and X4CrNiSiTi14-7 sheets

    International Nuclear Information System (INIS)

    Localized ageing and corresponding microstructural developments as a result of welding heat in the heat-affected zone (HAZ) of two different precipitation-hardened Cr-Steels (X5CrNiCuNb16-4 and X4CrNiSiTi14-7) have been studied. The X5CrNiCuNb16-4 sheet was in solution annealed condition and X4CrNiSiTi14-7 sheet was in peak aged condition. The results showed that despite of initial heat treated condition, the fusion zone formed in both welded sheets has typical cast structure. The HAZ has different microstructure compared to fusion zone and base metal. The HAZ is found to be sensitive to the welding heat and was aged locally due to thermal effects of welding. This localized ageing forms regions in HAZ varying from over-aged to under aged, depending upon the initial ageing condition of the base sheet

  6. Resistencia a la corrosión a alta temperatura de recubrimientos NiCrAlY y NiCrFeNbMoTiAl depositados por APS

    Directory of Open Access Journals (Sweden)

    José Luis Tristancho-Reyes

    2014-12-01

    Full Text Available La corrosión a alta temperatura de las tuberías utilizadas en equipos generadores de vapor (calderas ha sido reconocida como un grave problema que trae consigo el adelgazamiento de éstas y, por consiguiente, la falla de los equipos. En la última década se han incrementado las investigaciones que involucran recubrimientos protectores que ayudan de alguna manera a prolongar la vida útil de estos equipos. Esta investigación determinó el comportamiento de los recubrimientos NiCrAlY y NiCrFeNbMoTiAl depositados por proyección térmica asistida por plasma (APS sobre la aleación SA213 – T22 (2¼Cr – 1Mo, en un ambiente corrosivo de 80%V2O5–20%K2SO4 a 800°C. Los valores de la cinética de corrosión fueron determinados mediante resistencia a la polarización lineal (RPL y espectroscopia de impedancia electroquímica (EIE. Los resultados obtenidos muestran una menor cinética de corrosión en el recubrimiento NiCrFeNbMoTiAl que la presentada por el recubrimiento NiCrAlY, corroborado por Microscopia Electrónica de Barrido (MEB.

  7. Room-temperature sliding wear properties of laser melt deposited Cr13Ni5Si2/γalloy

    Institute of Scientific and Technical Information of China (English)

    FANG Yanli; WANG Huaming

    2007-01-01

    A wear-resistant alloy consisting of Cr13Ni5Si2 ternary silicide dendrites and the interdendritic nickel-base solid solution (γ) was designed and fabricated by the laser melting/continuous deposition (LMCD) process.The wear resistance of Cr13Ni5Si2/γalloy was evaluated on an MM-200 block-on-wheel dry sliding wear tester at room temperature. Results indicate that the Cr13Ni5Si2/γ alloy has excellent wear resistance and extremely low load-sensitivity of wear under dry sliding wear test conditions due to the high toughness and the high strength,as well as the transferred cover-layer on the worn surface of the alloy.

  8. Effect of Strain Rate on Deformation Behavior of AlCoCrFeNi High-Entropy Alloy by Nanoindentation

    Science.gov (United States)

    Tian, L.; Jiao, Z. M.; Yuan, G. Z.; Ma, S. G.; Wang, Z. H.; Yang, H. J.; Zhang, Y.; Qiao, J. W.

    2016-06-01

    In this study, nanoindentation tests with continuous stiffness measurement technique were measured to investigate the deformation behavior of a high-entropy alloy AlCoCrFeNi under different indentation strain rates at room temperature. Results suggest that the creep behavior exhibits remarkable strain rate dependence. In-situ scanning images showed a conspicuous pileup around the indents, indicating that an extremely localized plastic deformation occurred during the nanoindentation. Under different strain rates, elastic modulus basically remains unchanged, while the hardness decreases with increasing indentation depth due to the indentation size effect. Furthermore, the modulus and hardness of AlCoCrFeNi HEAs are greater than that of the Al x CoCrFeNi ( x = 0.3,0.5) at the strain rate of 0.2 s-1 due to its higher negative enthalpy of mixing related to the atomic binding force, and the solid solution strengthening induced by the lattice distortion, respectively.

  9. The characteristics of two-phase 22Cr-6Ni-2Mo-1,5Cu cast steel

    Directory of Open Access Journals (Sweden)

    B. Kalandyk

    2008-12-01

    Full Text Available The paper discusses the effect of the casting wall thickness on the segregation of alloying elements in two-phase (F-A 22Cr-6Ni-2Mo-1,5Cu cast steel. The values of the distribution coefficient k0 for Cr, Mo, Si, and Ni, Mn, Cu in the cast stepped test piece walls of three different thicknesses were determined. After solutioning, the values of Rm, R0,2, A5 and Z were measured in the wall of 45 mm thickness and were compared with the results obtained for austenitic cast steel of 18Cr-9Ni grade. In the examined cast steel also the content of δ ferrite and the value of PREN were determined.

  10. Cu2+、Cd2+和Cr6+对孔雀鱼的单一与联合毒性效应%Single and joint toxicity of Cu2+,Cd2+ and Cr6+ on Poecilia reticulata

    Institute of Scientific and Technical Information of China (English)

    赵岩; 孔强; 付荣恕

    2009-01-01

    采用静水生物测试法研究了Cu、Cd和Cr等重金属对孔雀鱼的单一与联合毒性效应.单一毒性试验结果表明:暴露时间为24,48,72和96 h时,Cu2+对孔雀鱼的LC50分别为5.70,4.02,2.95和2.36 mg/L,Cd2+对孔雀鱼的LC50分别为23.24,20.15,18.07和17.71 mg/L,Cr6+对孔雀鱼的LC50分别为88.56,65.21,47.81和43.40 mg/L.3种重金属离子对孔雀鱼均为高毒性,毒性大小为Cu2+>Cd2+>Cr6+.联合毒性试验表明:当浓度比为1:1或1:1:1,Cu2+与Cd2+、Cu2+与Cr6+、Cd2+与Cr6+以及Cu2+、Cd2+与Cr6+共存时的联合毒性均为毒性增强的协同作用.

  11. Study on structural, optical properties of solvothermally synthesized Ni doped CdS nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Kamaldeep, E-mail: kamalbillingz@gmail.com; Verma, N. K., E-mail: nkverma13@gmail.com [School of Physics, Material Science, Thapar University, Patiala (India)

    2015-05-15

    Undoped and alkali metal i.e Ni doped CdS nanorods (Cd{sub x}Ni{sub 1-x}S) with (x = 0.0, 0.3,) has been synthesized by using a convenient solvothermal technique. In order to confirm the structure of the synthesized nanorods X-ray diffraction (XRD) has been done which reveals the formation of hexagonal phase of the dilute magnetic semiconducting nanorods having size of undoped 27.79nm and doped 17.49nm. Energy dispersive X-ray analysis depicts the presence of elements Cd, Ni and S in their stoichiometric ratio. Optical behavior of undoped and doped nanorods has been investigated. UV-visible spectra show the blue shift in the band gap, as compared to the bulk CdS which may be due the quantum confinement occurs in the nanostructures. Morphological analysis has been done with the help of Transmission electron microscope which confirms the polycrystalline nature of the synthesized nanorods.

  12. The effect of ion implantation on the oxidation resistance of vacuum plasma sprayed CoNiCrAlY coatings

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Jie [Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Shanghai Institute of Ceramic, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Zhao Huayu; Zhou Xiaming [Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Shanghai Institute of Ceramic, Chinese Academy of Sciences, Shanghai 200050 (China); Tao Shunyan, E-mail: shunyantao@mail.sic.ac.cn [Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Shanghai Institute of Ceramic, Chinese Academy of Sciences, Shanghai 200050 (China); Ding Chuanxian [Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Shanghai Institute of Ceramic, Chinese Academy of Sciences, Shanghai 200050 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer We used ion implantation to improve the oxidation resistance of CoNiCrAlY coating. Black-Right-Pointing-Pointer The oxidation process of CoNiCrAlY coating at 1100 Degree-Sign C for 1000 h was studied. Black-Right-Pointing-Pointer The Nb ion implanted coating exhibited better oxidation resistance. Black-Right-Pointing-Pointer The influences of Nb and Al ion implantation into CoNiCrAlY coatings were evaluated. - Abstract: CoNiCrAlY coatings prepared by vacuum plasma spraying (VPS) were implanted with Nb and Al ions at a fluence of 10{sup 17} atoms/cm{sup 2}. The effects of ion implantation on the oxidation resistance of CoNiCrAlY coatings were investigated. The thermally grown oxide (TGO) formed on each specimen was characterized by XRD, SEM and EDS, respectively. The results showed that the oxidation process of CoNiCrAlY coatings could be divided into four stages and the key to obtaining good oxidation resistance was to remain high enough amount of Al and promote the lateral growth of TGO. The implantation of Nb resulted in the formation of continuous and dense Al{sub 2}O{sub 3} scale to improve the oxidation resistance. The Al implanted coating could form Al{sub 2}O{sub 3} scale at the initial stage, however, the scale was soon broken and TGO transformed to non-protective spinel.

  13. Kekuatan perlekatan geser semen ionomer kaca terhadap dentin dan NiCr alloy (Shear bond strenght of glass ionomer cement in dentin and NiCr alloy

    Directory of Open Access Journals (Sweden)

    Mira Leonita

    2006-03-01

    Full Text Available Glass ionomer cements were used broadly in restorative dentistry. That’s why researchers always try to invent new form of glass ionomer cement. The newest invention was the paste-paste formulation. Shear bond strenght of powder-liquid glass ionomer cement and paste-paste glass ionomer cement in dentin and NiCr alloy was tested to 4 groups of samples. Each group consisted contain 6 samples that were shaped into cylinder with 4 mm of diameter and 5 mm of height. Group A was dentin with powder-liquid glass ionomer cement, group B was dentin with paste-paste glass ionomer cement, group C was alloy with powder-liquid glass ionomer cement, and group D was alloy with paste-paste glass ionomer cement. Each sample in each group was tested with Autograph. The datas were analyzed statistically using T-test with level of signficance 0.05. The result showed that powder-liquid glass ionomer cement shear bond strenght was 211 N and paste-paste glass ionomer cement was 166.92 N. That showed that powder-liquid glass ionomer cement had a better shear bond strenght.

  14. Creep and Oxidation Behavior of Modified CF8C-Plus with W, Cu, Ni, and Cr

    Science.gov (United States)

    Unocic, Kinga A.; Dryepondt, Sebastien; Yamamoto, Yukinori; Maziasz, Philip J.

    2016-04-01

    The microstructures of modified CF8C-Plus (Fe-19Cr-12Ni-0.4W-3.8Mn-0.2Mo-0.6Nb-0.5Si-0.9C) with W and Cu (CF8CPWCu) and CF8CPWCu enhanced with 21Cr + 15Ni or 22Cr + 17.5Ni were characterized in the as-cast condition and after creep testing. When imaged at lower magnifications, the as-cast microstructure was similar among all three alloys as they all contained a Nb-rich interdendritic phase and Mn-based inclusions. Transmission electron microscopy (TEM) analysis showed the presence of nanoscale Cu-rich nanoprecipitates distributed uniformly throughout the matrix of CF8CPWCu, whereas in CF8CPWCu22/17, Cu precipitates were found primarily at the grain boundaries. The presence of these nanoscale Cu-rich particles, in addition to W-rich Cr23C6, nanoscale Nb carbides, and Z-phase (Nb2Cr2N2), improved the creep strength of the CF8CPWCu steel. Modification of CF8CPWCu with Cr and Ni contents slightly decreased the creep strength but significantly improved the oxidation behavior at 1073 K (800 °C). In particular, the addition of 22Cr and 17.5Ni strongly enhanced the oxidation resistance of the stainless steel resulting in a 100 degrees or greater temperature improvement, and this composition provided the best balance between improving both mechanical properties and oxidation resistance.

  15. Semi-solid slurry preparation and rolling of 1Cr18Ni9Ti stainless steel

    Institute of Scientific and Technical Information of China (English)

    Weimin Mao; Aimin Zhao; Dong Yun; Leping Zhang; Xueyou Zhong

    2003-01-01

    The preparation and rolling of the semi-solid slurry 1Crl8Ni9Ti stainless steel were researched. The experimental results show that when stirred for 2-3 min under the given test condition, the semi-solid slurry with about 50%-60% (volume fraction) solid and the spherical primary austenitic grains in the size of 100-200 μm can be obtained, and it is easy to be discharged from the bottom little hole of the stirring chamber. The semi-solid slurry of 1Crl8Ni9Ti stainless steel can be rolled into the given plate successfully.However, the solid phase and liquid phase are easily separated in the rolling process, so that the solid primary austenitic grains are concentrated in the center and the liquid phase is near the edge of the rolled plate. The strengths of the plate rolled in the semi-solid state are higher than that of the traditionally repeated hot-rolled plate of 1Cr18Ni9Ti stainless steel.

  16. Determination of γ′+γ / γ Phase Boundary in Ni-Al-Cr System Using DTA Thermal Analysis

    Directory of Open Access Journals (Sweden)

    Maciąg T.

    2016-03-01

    Full Text Available Mechanical properties at elevated temperature, in modern alloys based on intermetallic phase Ni3Al are connected with phase composition, especially with proportion of ordered phase γ′ (L12 and disordered phase γ (A1. In this paper, analysis of one key systems for mentioned alloys - Ni-Al-Cr, is presented. A series of alloys with chemical composition originated from Ni-rich part of Ni-Al-Cr system was prepared. DTA thermal analysis was performed on all samples. Based on shape of obtained curves, characteristic for continuous order-disorder transition, places of course of phase boundaries γ′+γ / γ were determined. Moreover, temperature of melting and freezing of alloys were obtained. Results of DTA analysis concerning phase boundary γ′+γ / γ indicated agreement with results obtained by authors using calorimetric solution method.

  17. Changes of Tempering Microstructure and Properties of Fe-Cr-V-Ni-Mn-C Cast Alloys

    Institute of Scientific and Technical Information of China (English)

    LIU Yan-xia; MA Yong-qing; WANG Yue-hua; ZHANG Zhan-ping; ZHANG Yang

    2004-01-01

    The changes of tempering microstructure and properties of Fe-Cr-V-Ni-Mn-C cast alloys with martensite matrix and much retained austenite are studied. The results showed that when tempering at 200℃ the amount of retained austenite in the alloys is so much that is nearly to as-cast, and a lot of retained austenite decomposes when tempering at 350℃ and the retained austenite decomposes almost until tempering at 560℃. When tempering at 600℃, the retained austenite in the alloys all decomposes. At 560℃ the hardness is highest due to secondary hardening. The effect of nickel and manganese on the microstructure and properties of Fe-Cr-V-C cast alloy were also studied. The results show that the Fe-Cr-V-C cast alloy added nickel and manganese can obtain martensite matrix and much retained austenite microstructure, and nickel can also prevent pearlite transformation. With the increasing content of nickel and manganese, the hardness of as-cast alloy will decreases gradually, so one can improve the hardness of alloy by tempering process. When the content of nickel and manganese is 1.3~1.7%, the hardness of secondary hardening is the highest (HRC64). But when the content of nickel and manganese increase continually, the hardness of secondary hardening is low slightly, and the tempering temperature of secondary hardening rises.

  18. A new oxochromate: SrNi2Cr8O15 of the BaV10O15 type

    International Nuclear Information System (INIS)

    A new quaternary oxochromate(III) was prepared by solid state reaction. Single crystal X-ray investigations of SrNi2Cr8O15 show that this compound belongs to the BaV10O15type. [Space group D2h18-Ccmb, a = 10,042; b = 11,413; c = 9,260A; Z = 4.] Ni2+ and Cr3+ occupy the octahedrally coordinated point positions statistically. The surrounding of Sr2+ is similar to the iso- and heteropolyacids. (Author)

  19. Study of the microstructure and of microhardness variation of a Ni-Fe-Cr austenitic alloy by niobium

    International Nuclear Information System (INIS)

    The mechanisms of hardening and corrosion resistance increase in Ni-Fe-Cr austenitic stainless steels by Nb additions are of interest to nuclear technology Niobium additions to a 321 type stainless steel were made in order to study the microhardness, electrical resistivity and metallography. Experimental measurements results are shown. The effect of Nb additions as a micro-alloying element and the thermal and mechanical processes (cold working in particular) in the microstructure and microhardness properties of the 11% Ni - 70%Fe - 17% Cr austenitic alloys were studied. (Author)

  20. ELECTROOXIDATION OF METHANOL ON PT MODIFIED WITH ADATOMS (NI, CU, PB, CD)

    OpenAIRE

    A.Khouchaf; D. Takky; M. E1 M. Chbihi; S. Benmokhtar

    2015-01-01

    The electro oxidation of methanol has been studied in alkaline medium NaOH 0.1 M and acid medium H2SO4 0.5 M on a platinum electrode and a platinum modified by adatom adsorption (Ni, Cu, Pb, and Cd). The influence of different experimental variables (methanol concentration, and temperature) is reported. Preliminary investigations by cyclic voltammetry showed that the catalytic activity of platinum is still too low to be considered as a practical catalyst. Underpotential deposition of lead, ni...

  1. High performance NiFe layered double hydroxide for methyl orange dye and Cr(VI) adsorption.

    Science.gov (United States)

    Lu, Yi; Jiang, Bin; Fang, Liang; Ling, Faling; Gao, Jiemei; Wu, Fang; Zhang, Xihua

    2016-06-01

    The NiFe layered double hydroxides (LDHs) with different mole ratio of Ni/Fe (4:1, 3:1, 7:3 and 1:1) were prepared by a simple coprecipitation method. The adsorption performance were evaluated by the removal of methyl orange (MO) dye and hexavalent chromium(VI) heavy metal ion. It is found that Ni4Fe1-LDH can remove more than 92% of MO in 10 min at the 10 mg/L MO initial concentration, and 97% of Cr(VI) in 1 h at 4 mg/L Cr2O7(2-) initial concentration. The saturated adsorption capacity of Ni4Fe1-LDH is found to be as large as 205.76 mg/g for MO and 26.78 mg/g for Cr(VI). The adsorption behavior of this new adsorbent is fitted well with Langmuir isotherm and the pseudo-second-order kinetic model, indicative of a monolayer and chemical adsorption that synergistically originates from exchangeable anions mechanism and layer charge density. Due to the excellent removal capacity of MO and Cr(VI), the NiFe-LDHs could be a promising adsorbent for wastewater treatment. PMID:26999751

  2. Evaluation of Cyclic Oxidation and Hot Corrosion Behavior of HVOF-Sprayed WC-Co/NiCrAlY Coating

    Science.gov (United States)

    Somasundaram, B.; Kadoli, Ravikiran; Ramesh, M. R.

    2014-08-01

    Corrosion of metallic structural materials at an elevated temperature in complex multicomponent gas environments are potential problems in many fossil energy systems, especially those using coal as a feedstock. Combating these problems involves a number of approaches, one of which is the use of protective coatings. The high velocity oxy fuel (HVOF) process has been used to deposit WC-Co/NiCrAlY composite powder on two types of Fe-based alloys. Thermocyclic oxidation behavior of coated alloys was investigated in the static air as well as in molten salt (Na2SO4-60%V2O5) environment at 700 °C for 50 cycles. The thermogravimetric technique was used to approximate the kinetics of oxidation. WC-Co/NiCrAlY coatings showed a lower oxidation rate in comparison to uncoated alloys. The oxidation resistance of WC-Co/NiCrAlY coatings can be ascribed to the oxide layer of Al2O3 and Cr2O3 formed on the outermost surface. Coated alloys extend a protective oxide scale composed of oxides of Ni and Cr that are known to impart resistance to the hot corrosion in the molten salt environment.

  3. Porous nano-Al2O3/Fe-Cr-Ni composites fabricated by pressureless reactive sintering

    International Nuclear Information System (INIS)

    Highlights: → Porous Al2O3/Fe-Cr-Ni composites were prepared via pressureless reactive sintering. → Porous structure became homogeneous with increasing of the prepressing pressure. → Mechanical properties were influenced by pore structure and content of metal phase. - Abstract: Porous in situ nano-Al2O3 reinforced Fe-Cr-Ni metal matrix composites (MMCs) were fabricated from a mixture of Al/nano-Fe2O3/Cr/Ni powders via pressureless reactive sintering at 700-800 deg. C for 1-2 h. X-ray diffraction (XRD) demonstrated that the porous composites produced at 800 deg. C for 2 h consisted of Al2O3, Cr0.7Fe0.36Ni2.9 and Fe-Cr phases generally. Scanning electron microscopy (SEM) showed that the Al2O3 particles were ultrafine and uniformly distributed in the metal matrix. The pore sizes ranged from 1 μm to 20 μm for the sintered porous composites fabricated at 800 deg. C for 2 h. The resultant porous composite prepared under prepressing pressure of 200 MPa before sintering had more homogeneous and finer pore structure, lower porosity and higher bending strength and fracture toughness than those prepared under prepressing pressure of 5-100 MPa.

  4. Salt-bath Nitriding Process for 32 Cr2 Mo2 NiVNb Steel%32 Cr2 Mo2 NiVNb钢盐浴氮化工艺

    Institute of Scientific and Technical Information of China (English)

    高志恒; 付扬帆

    2015-01-01

    Objective To develop a new salt-bath nitriding process for 32Cr2Mo2NiVNb steel surface treatment. Methods The 32Cr2Mo2NiVNb steel was treated with the new salt-bath nitriding process. The influences of the new salt-bath nitriding process on the microstructure and mechanical properties of 32Cr2Mo2NiVNb steel were concluded based on the analysis of several tests such as salt spray test and hardness test. The applicability of the salt-bath nitriding process for 32Cr2Mo2NiVNb steel was verified in this paper. Results After the salt-bath nitriding process, the 32Cr2Mo2NiVNb base material was composed of uniform fine needle-like sorbite + small amount of free ferrite, the depth of the nitriding layer was about 0. 23 mm, and the compound layer showed an even thickness of about 17μm. The level of the brittleness, nervation and wave-like nitrid, porosity of nitrided case all reached grade I. The hardness of 32Cr2Mo2NiVNb steel surface after salt-bath nitriding treatment was 1011HV0. 3, which was 250% of the surface hardness without salt-bath nitriding treatment. The tensile strength and the fracture morphology showed no significant change after salt-bath nitriding treatment. The tensile length after fracture, the reduction of cross-section area and impact absorption energy were slightly decreased. The time of resistance to neutral salt spray was 6. 3 fold as high as that of the sample coated with hard chromi-um. The surface wear scars after wear at high temperature for 190 s were fine and uniform, and the wear weight loss was reduced by 62. 8% as compared to the sample coated with hard chromium. Conclusion The salt-bath nitriding process did not damage the microstructure and mechanical properties of 32Cr2Mo2NiVNb steel, with only slight decreased in plasticity and toughness indexes, and could significantly improve the corrosion resistance and high-temperature wear resistance of 32Cr2Mo2NiVNb steel as compared to hard chromium plating. The new salt-bath nitriding process

  5. Análisis mecánico y tribológico de los recubrimientos fe-cr-ni-c y ni-al-mo

    Directory of Open Access Journals (Sweden)

    JORGE E. MUÑOZ

    2007-01-01

    Full Text Available En este trabajo de investigación se evaluaron dos recubrimientos aplicados por medio de la técnica de rociado térmico por combustión, la aleación: Ni=89%, Al = 5,5%, Mo=5,5% y la aleación Fe=81,8%, Cr=16%, Ni=2%, C=0,2. La preparación superficial de las probetas se realizó usando chorro de arena. Se realizaron pruebas de resistencia al cortante, adherencia, desgaste abrasivo, desgaste por deslizamiento y flexión en cuatro puntos. El recubrimiento Fe-Cr-Ni-C presentó menor pérdida de masa, tanto para desgaste abrasivo como para el desgaste por deslizamiento. La multicapa presentó una mayor porosidad en el recubrimiento Ni-Al- Mo usado como capa base y la capa exterior de Fe-Cr-Ni-C presentó mayor cantidad de partículas no fundidas y óxidos. La falla ocurrida en el ensayo de adherencia para las probetas con recubrimiento multicapa fue de característica adhesiva y cohesiva. El esfuerzo en el que se presenta la fisura por flexión en el recubrimiento multicapa disminuyó con el aumento del espesor

  6. Stress release phenomena in chromia scales formed on NiCr-30 alloys: Influence of metallurgical parameters

    Science.gov (United States)

    Guerain, M.; Goudeau, P.; Grosseau-Poussard, J. L.

    2011-11-01

    Stress release phenomena are studied for α-Cr2O3 thermal oxide films grown on NiCr-30 alloys. The influence of specific metallurgical parameters, such as cooling rate and initial surface roughness, is investigated thanks to Raman spectroscopy. Systematic correlations are established between the residual stress level in the scales and the damage rate resulting from a delamination process by buckling. Different buckling morphologies are characterized mainly according to the cooling rate range.

  7. Partition coefficients for Al, Ca, Ti, Cr, and Ni in olivine obtained by melting experiment on an LL6 chondrite

    Science.gov (United States)

    Miyamoto, M.; Mikouchi, T.; Mckay, G. A.

    1994-01-01

    We report the partition coefficients for Ca, Al, Ti, Cr, and Ni in olivine obtained through a series of melting experiments on an LL6 chondrite under varying conditions of temperature and oxygen fugacity. It is necessary to examine the variation of partition coefficients up to extremely reducing conditions in order to study meteoritic olivines. For Ca, Al, and Cr, the partition coefficients tend to decrease as temperature increases, but do not change even under extremely reducing conditions.

  8. NiCr (x) Fe2-x O-4 as cathode materials for electrochemical reduction of NO (x)

    DEFF Research Database (Denmark)

    Bræstrup, Frantz Radzik; Kammer Hansen, Kent

    2010-01-01

    Solid solutions of spinel-type oxides with the composition NiCr x Fe2-x O4 (x = 0.0, 0.5, 1.0, 1.5, 2.0) were prepared with the glycine–nitrate combustion synthesis. Four-point DC resistivity measurements show an increase in the conductivity as more Cr is introduced into the structure, whereas...

  9. Magnetic cluster expansion model for random and ordered magnetic face-centered cubic Fe-Ni-Cr alloys

    Science.gov (United States)

    Lavrentiev, M. Yu.; Wróbel, J. S.; Nguyen-Manh, D.; Dudarev, S. L.; Ganchenkova, M. G.

    2016-07-01

    A Magnetic Cluster Expansion model for ternary face-centered cubic Fe-Ni-Cr alloys has been developed, using DFT data spanning binary and ternary alloy configurations. Using this Magnetic Cluster Expansion model Hamiltonian, we perform Monte Carlo simulations and explore magnetic structures of alloys over the entire range of compositions, considering both random and ordered alloy structures. In random alloys, the removal of magnetic collinearity constraint reduces the total magnetic moment but does not affect the predicted range of compositions where the alloys adopt low-temperature ferromagnetic configurations. During alloying of ordered fcc Fe-Ni compounds with Cr, chromium atoms tend to replace nickel rather than iron atoms. Replacement of Ni by Cr in ordered alloys with high iron content increases the Curie temperature of the alloys. This can be explained by strong antiferromagnetic Fe-Cr coupling, similar to that found in bcc Fe-Cr solutions, where the Curie temperature increase, predicted by simulations as a function of Cr concentration, is confirmed by experimental observations. In random alloys, both magnetization and the Curie temperature decrease abruptly with increasing chromium content, in agreement with experiment.

  10. Cd and Ni transport and accumulation in the halophyte Sesuvium portulacastrum: implication of organic acids in these processes.

    Science.gov (United States)

    Mnasri, Mejda; Ghabriche, Rim; Fourati, Emna; Zaier, Hanen; Sabally, Kebba; Barrington, Suzelle; Lutts, Stanley; Abdelly, Chedly; Ghnaya, Tahar

    2015-01-01

    The implication of organic acids in Cd and Ni translocation was studied in the halophyte species Sesuvium portulacastrum. Citric, fumaric, malic, and ascorbic acids were separated and quantified by HPLC technique in shoots, roots and xylem saps of plants grown on nutrient solutions added with 50 μM Cd, 100 μM Ni and the combination of 50 μM Cd + 100 μM Ni. Results showed that Cd had no significant impact on biomass production while Ni and the combination of both metals drastically affected plant development. Cadmium and Ni concentrations in tissues and xylem sap were higher in plants subjected to individual metal application than those subjected to the combined effect of Cd and Ni suggesting a possible competition between these metals for absorption. Both metals applied separately or in combination induced an increase in citrate concentration in shoots and xylem sap but a decrease of this concentration in the roots. However, a minor relationship was observed between metal application and fumaric, malic, and ascorbic acids. Both observations suggest the implication of citric acid in Cd, Ni translocation and shoot accumulation in S. portulacastrum. The relatively high accumulation of citric acid in xylem sap and shoot of S. portulacastrum could be involved in metal chelation and thus contributes to heavy metal tolerance in this species. PMID:25821455

  11. Cd and Ni transport and accumulation in the halophyte Sesuvium portulacastrum: implication of organic acids in these processes

    Directory of Open Access Journals (Sweden)

    Tahar eGhnaya

    2015-03-01

    Full Text Available The implication of organic acids in Cd and Ni translocation was studied in the halophyte species Sesuvium portulacastrum. Citric, fumaric, malic and ascorbic acids were separated and quantified by HPLC technique in shoots, roots and xylem saps of plants grown on nutrient solutions added with 50 µM Cd, 100 µM Ni and the combination of 50 µM Cd + 100 µM Ni. Results showed that Cd had no significant impact on biomass production while Ni and the combination of both metals drastically affected plant development. Cadmium and Ni concentrations in tissues and xylem sap were higher in plants individually exposed to heavy metal application than in those subjected to the combined treatment Cd + Ni, suggesting a possible competition between these metals for absorption. Both metals applied separately or in combination induced an increase in citrate concentration in shoots and xylem sap but a decrease of this concentration in the roots. However a minor relationship was observed between metal application and fumaric, malic and ascorbic acids. Both observations suggest the implication of citric acid in Cd, Ni translocation and shoot accumulation in S. portulacastrum. The relatively high accumulation of citric acid in xylem sap and shoot of S. portulacastrum could be involved in metal chelation and thus contributes to heavy metal tolerance in this species.

  12. Microstructure evolution in proton-irradiated austenitic Fe-Cr-Ni alloys under LWR core conditions

    Science.gov (United States)

    Gan, Jian

    1999-11-01

    Irradiation-induced microstructure of austenitic stainless steel was investigated using proton irradiation. High-purity alloys of Fe-20Cr-9Ni (UHP 304 SS), Fe-20Cr-24Ni and Ni-18Cr-9Fe were irradiated using 3.2 MeV protons at a dose rate of 7 × 10-6 dpa/s between 300°C and 600°C. The irradiation produced a microstructure consisting of dislocation loops and voids. The dose and temperature dependence of the number density and size of dislocation loops and voids were investigated. The changes in yield strength due to irradiation were estimated from Vickers hardness measurements and compared to calculations using a dispersed-barrier hardening model. The dose and temperature dependence of microstructure and hardness change for proton irradiation follows the same trend as that for neutron irradiation at comparable irradiation conditions. Commercial purity alloys of CP 304 SS and CP 316 SS were irradiated at 360°C to doses between 0.3 and 3.0 dpa. The irradiated microstructure consists of dislocation loops. No voids were detected at doses up to 3.0 dpa. Loop size distributions are in close agreement with that in the same alloys neutron-irradiated in a LWR core. The loop density also agrees with neutron irradiation data. The yield strength as a function of dose in proton irradiated commercial purity alloys is consistent with the neutron- data trend. A fast-reactor microstructure model was adapted for light water reactor (LWR) irradiation conditions (275°C, 7 × 10 -8 dpa/s) and then applied to proton irradiation under conditions (360°C, 7 × 10-6 dpa/s) relevant to LWRs. The original model was modified by including in-cascade interstitial clustering and the loss of interstitial clusters to sinks by cluster diffusion. It was demonstrated that loop nucleation for both LWR irradiation condition and proton irradiation are driven by in-cascade interstitial clustering. One important result from this modeling work is that the difference in displacement cascade between

  13. 真空热处理对镍基单晶高温合金溅射NiCrAlY涂层抗氧化性能的影响%EFFECT OF VACUUM HEAT TREATMENT ON OXIDATION RESISTANCE OF SPUTTERED NiCrAlY COATING ON A Ni-BASE SINGLE-CRYSTAL SUPERALLOY

    Institute of Scientific and Technical Information of China (English)

    李美姮; 张重远; 孙晓峰; 胡望宇; 金涛; 管恒荣; 胡壮麒

    2002-01-01

    用磁控溅射法在镍基单晶高温合金基体上沉积NiCrAlY涂层,研究了真空热处理对涂层组织结构及抗氧化性能的影响.结果表明,溅射NiCrAlY涂层主要由γ-Ni和β-NiAl两相组成,元素分布均匀;经真空热处理后,涂层主要由γ′-Ni3Al、β-NiAl相和极少量的α-Al2O3相组成,元素分布变得不均匀,最外层富Al贫Cr.真空热处理可使溅射NiCrAlY涂层表面较早生成保护性能良好的α-Al2O3.1000℃氧化200 h,溅射涂层氧化膜有较大部分已经剥落,但真空热处理涂层的氧化膜仍较好地粘附在涂层基体上.真空热处理使溅射NiCrAlY涂层表面生成的氧化膜粘附性更好,提高了溅射NiCrAlY涂层的抗氧化性能.

  14. Recovery of cadmium by high-temperature vaccum evaporation from Ni-Cd batteries

    Institute of Scientific and Technical Information of China (English)

    朱建新; 李金惠; 聂永丰; 于波

    2003-01-01

    High-temperature vaccum evaporation is a recycling technology that includes a selective material recovering process. The fundamental research on a process of disassembling and recovering selected materials from Ni-Cd batteries was conducted using self-designed experimental apparatus. An effective recycling technology based on the evaporation phenomenon of batteries and the elements of cadmium under the laboratory condition was studied. The results show that: (1)Ni/Cd can be effectively recovered by vacuum distillation at appropriate temperature, pressure and time, and high purity cadmium (>99%) can be obtained through the process; (2)the effective distillatory temperature should be at the range of 573-1173K; (3)the higher the evaporation temperature, the lower the purity of cadmium in condensate metal

  15. Low cost RISC implementation of intelligent ultra fast charger for Ni-Cd battery

    Energy Technology Data Exchange (ETDEWEB)

    Petchjatuporn, Panom; Khaehintung, Noppadol [Department of Control and Instrumentation Engineering, Faculty of Engineering, Mahanakorn University of Technology, Bangkok 10530 (Thailand); Sirisuk, Phaophak; Sunat, Khamron [Department of Computer Engineering, Faculty of Engineering, Mahanakorn University of Technology, Bangkok 10530 (Thailand); Wicheanchote, Phinyo [Test Engineering Department, Sanmina-SCI Systems Co. Ltd. (Thailand); Kiranon, Wiwat [Department of Telecommunication Engineering, Faculty of Engineering, King Mongkut' s Institue of Technology, Ladkrabang, Bangkok 10520 (Thailand)

    2008-02-15

    This paper presents a low cost reduced instruction set computer (RISC) implementation of an intelligent ultra fast charger for a nickel-cadmium (Ni-Cd) battery. The charger employs a genetic algorithm (GA) trained generalized regression neural network (GRNN) as a key to ultra fast charging while avoiding battery damage. The tradeoff between mean square error (MSE) and the computational burden of the GRNN is addressed. Besides, an efficient technique is proposed for estimation of a radial basis function (RBF) in the GRNN. Hardware realization based upon the techniques is discussed. Experimental results with commercial Ni-Cd batteries reveal that while the proposed charger significantly reduces the charging time, it scarcely deteriorates the battery energy storage capability when compared with the conventional charger. (author)

  16. Aqueous synthesis and characterization of Ni, Zn co-doped CdSe QDs

    Science.gov (United States)

    Thirugnanam, N.; Govindarajan, D.

    2016-01-01

    Ni, Zn co-doped CdSe quantum dots (QDs) were synthesized by chemical precipitation method through aqueous route. The prepared QDs were characterized by X-ray diffraction (XRD) technique, UV-Vis absorption spectroscopy, photoluminescence (PL) spectroscopy and high resolution transmission electron microscopy (HRTEM). XRD technique results indicate that the prepared samples have a zinc blende cubic phase. From UV-Vis absorption spectroscopy technique, the prepared samples were blue shifted with respect to their bulk counter part due to quantum confinement effect. Among different doping ratios examined, a maximum PL emission intensity was observed for CdSe:Ni(1 %):Zn(1 %) QDs. HRTEM pictures show that the prepared QDs were in spherical shape.

  17. Bioleaching of spent Zn-Mn or Ni-Cd batteries by Aspergillus species.

    Science.gov (United States)

    Kim, Min-Ji; Seo, Ja-Yeon; Choi, Yong-Seok; Kim, Gyu-Hyeok

    2016-05-01

    This research explores the recovery of metals from spent Zn-Mn or Ni-Cd batteries by a bioleaching using six Aspergillus species. Two different nutrients, malt extract and sucrose, were used to produce different types of organic acids. Oxalic acid and citric acid were shown to be the dominant organic acid in malt extract and sucrose media, respectively. In the bioleaching, the metal removal was higher in sucrose media than malt extract. All species, except A. niger KUC5254, showed more than 90% removal of metals from Zn-Mn battery. For Ni-Cd battery, more than 95% of metals was extracted by A. niger KUC5254 and A. tubingensis KUC5037. As a result, A. tubingensis KUC5037 which is a non-ochratoxigenic fungus was considered to have the greatest potential for improving the safety and efficiency of the bioleaching. PMID:26584557

  18. On the Path to Optimizing the Al-Co-Cr-Cu-Fe-Ni-Ti High Entropy Alloy Family for High Temperature Applications

    Directory of Open Access Journals (Sweden)

    Anna M. Manzoni

    2016-03-01

    Full Text Available The most commonly investigated high entropy alloy, AlCoCrCuFeNi, has been chosen for optimization of its microstructural and mechanical properties by means of compositional changes and heat treatments. Among the different available optimization paths, the decrease of segregating element Cu, the increase of oxidation protective elements Al and Cr and the approach towards a γ-γ′ microstructure like in Ni-based superalloys have been probed and compared. Microscopical observations have been made for every optimization step. Vickers microhardness measurements and/or tensile/compression test have been carried out when the alloy was appropriate. Five derived alloys AlCoCrFeNi, Al23Co15Cr23Cu8Fe15Ni16, Al8Co17Cr17Cu8Fe17Ni33, Al8Co17Cr14Cu8Fe17Ni34.8Mo0.1Ti1W0.1 and Al10Co25Cr8Fe15Ni36Ti6 (all at.% have been compared to the original AlCoCrCuFeNi and the most promising one has been selected for further investigation.

  19. The quenching influence on defect structure and far acting stress fields of the 30CrNi3MoVA steel

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ The determination of the quenching influence on defect structure and far acting stress fields of the cast constructional steel 30CrNi3MoVA (0.3%C, 1%Cr, 3%Ni, 1%Mo, 1%V) was the purpose of this work.

  20. The quenching influence on defect structure and far acting stress fields of the 30CrNi3MoVA steel

    Institute of Scientific and Technical Information of China (English)

    Kozlov; E.; V.; Popova; N.; A.; Klimashin; S.; I.; Tsellermaer; V.V.; Konovalov; S.; V.; Gromov; V.; E.

    2005-01-01

    The determination of the quenching influence on defect structure and far acting stress fields of the cast constructional steel 30CrNi3MoVA (0.3%C, 1%Cr, 3%Ni, 1%Mo, 1%V) was the purpose of this work.……

  1. Analysis on corrosion cracking causes of 0Cr18Ni9 stainless steel pipe fittings%0Cr18Ni9不锈钢管件腐蚀开裂原因分析

    Institute of Scientific and Technical Information of China (English)

    胡万明

    2012-01-01

    Some 0Cr18Ni9 stainless steel pipe fittings corrosion cracked before and during trial run of PVC project.Through referring the material of cracked fittings and construction documents and performing metallographic examination and chemical element analysis,the cracking causes were found.The causes included ① the purchased 0Cr18Ni9 stainless steel pipe fittings didn't comply with the design requirements;② water for pressure test contained exessive chloride ions and didn't meet the requirements and wasn't discharged in time;③ effective supervision and management were poor.%通过查找相关材质和施工资料及金相与化学元素分析,找出了聚氯乙烯项目试车前和试车过程中0Cr18Ni9不锈钢管件腐蚀开裂的原因:①采购的0Cr18Ni9不锈钢管件不符合设计要求;②试压水不符合要求,氯离子含量超标,且试压水未及时排放;③缺少有效的监督管理。

  2. Corrosion behaviors of a γ-toughened Cr13Ni5Si2/Cr3Ni5Si2 multi-phase ternary metal silicide alloy in NaCl solution

    International Nuclear Information System (INIS)

    Corrosion behaviors of a novel corrosion-resistant γ-toughened Cr13Ni5Si2/Cr3Ni5Si2 multi-phase ternary metal silicide alloy and properties of the passive film formed in NaCl solution were examined by anodic polarization, cyclic polarization and electrochemical impedance spectroscopy (EIS) experiments as well as X-ray photoelectron spectroscopy (XPS) and potentiostatic polarization measurements. Effects of immersion time and chloride ion concentration on corrosion behaviors of the alloy were also evaluated. Results indicated that the alloy exhibited excellent corrosion resistance in NaCl solution due to the spontaneous formation of a compact and protective passive film composed mainly of chromium (III) oxide as well as the high chemical stability and strong inter-atomic bonds inherent to Cr13Ni5Si2 and Cr3Ni5Si2 intermetallic phases. Moreover, corrosion resistance of the alloy was quite insensitive to the increase of chloride ion concentration and was improved noticeably with the increasing immersion time

  3. Study on Anti-ablation Property of CrNiMo Steel Irradiated by Laser%CrNiMo钢激光淬火处理的抗烧蚀性能研究

    Institute of Scientific and Technical Information of China (English)

    王文凯; 明学勤

    2009-01-01

    通过激光淬火表面强化技术,在CrNiMo钢表面形成马氏体相变的表面强化薄层.采用小电流累积烧蚀方法分解了材料烧蚀过程;对比分析相同烧蚀条件下CrNiMo钢在激光处理与未经激光处理的表面烧蚀形貌及其烧蚀质量差.结果表明:激光淬火确实能提高材料的抗烧蚀性能.%The thin strengthening layer on the CrNiMo steel surface was prepared by laser surface hardening. The ablation process of the steel was decomposed by the method of accumulated ablation with low current. The ablation surface and mass difference of the original steel and the steel irradiated by laser were analyzed. The results show that the CrNiMo steel through laser guenching indeed promotes the anti-ablation properties of the material.

  4. 1Cr18Ni9Ti不锈钢管的泄漏及控制方案%Leakage and control of 1Cr18Ni9Ti stainless steel pipe

    Institute of Scientific and Technical Information of China (English)

    吴志亚

    2014-01-01

    1Cr18Ni9Ti 是一种应用广泛的奥氏体不锈钢。焊接后,会使接头耐蚀性明显下降,会产生晶间腐蚀和应力腐蚀开裂。分析1Cr18Ni9Ti 的焊接性、食品回收管发生泄漏的原因,针对材料特点,采用焊条电弧焊补焊,通过选用合理的焊接材料、焊前准备、焊接工艺来保证焊接质量。%1Cr18Ni9Ti is a kind of austenitic stainless steel which is widely used. After welding,it can make the joint corrosion resist-ance decrease obviously,and mainly produces the intercrystalline corrosion and stress corrosion cracking. This article analyzes the weldability of 1Cr18Ni9Ti and the reasons for leakage of food recycling pipe. According to the characteristics of the material,adopt e-lectrode arc welding in repair welding process ,by choosing reasonable welding materials,welding preparation and welding process so as to guarantee the welding quality.

  5. Current Technology Research Status of Ni80Cr20 High Resistance Alloys for Electrical Heating%Ni80Cr20高电阻电热合金的工艺技术研究现状

    Institute of Scientific and Technical Information of China (English)

    于朝清; 易立; 徐永红; 章应; 朱强军; 代红伟

    2014-01-01

    The nickel-based alloy Ni80Cr20 is widely used as a kind of high resistance alloys for electrical heating materials. The paper introduces the research status of technology preparing Ni80Cr20 materials, including composition of design, smelting and ingot casting, processing, and heat treatment. The quality gap existing in the similar products in China and abroad, and the research focus in future are indicated.%镍基电阻合金Ni80Cr20是应用广泛的高电阻电热合金材料。本文介绍了Ni80Cr20高电阻电热合金材料的成分设计、熔炼铸锭、加工及热处理等工艺技术研究现状,并指出了国内外同类产品质量差距以及今后研究人员需要关注的重点。

  6. Effects of a Tantalum Addition on the Morphological and Compositional Evolutions of a Model Ni-AL-Cr Superalloy

    Science.gov (United States)

    Booth-Morrison, Christopher; Seidman, David N.; Noebe, Ronald D.

    2008-01-01

    The effects of a 2.0 at.% addition of Ta to a model Ni-Al-Cr superalloy aged at 1073 K are assessed using scanning electron microscopy and atom-probe tomography. The addition of Ta results in appreciable strengthening, and the morphology is found to evolve from a bimodal distribution of spheroidal precipitates, to cuboidal precipitates aligned along the elastically soft -type directions. Tantalum is observed to partition preferentially to the gamma -precipitate phase and decreases the mobility of Ni in the gamma- matrix sufficiently to cause an accumulation of Ni on the gamma-matrix side of the gamma -precipitate/gamma-matrix heterophase interface.

  7. Application of small punch creep testing to a thermally sprayed CoNiCrAlY bond coat

    OpenAIRE

    H. Chen; Hyde, T. H.; Voisey, K.T.; McCartney, D.G.

    2013-01-01

    High velocity oxy-fuel thermal spraying was used to prepare free-standing CoNiCrAlY (Co–31.7% Ni–20.8% Cr–8.1% Al–0.5% Y (wt%)) bond coat alloy samples approximately 0.5 mm thick. Creep tests were conducted at 750 °C on these samples using a small punch (SP) creep test method. The samples were characterised before and after creep testing using scanning electron microscopy with electron backscatter diffraction (EBSD). EBSD revealed a two phase fcc γ-Ni and bcc B2 β-NiAl microstructure with gra...

  8. Repair of NiCoCrAlY Overlay Coating on Ni3Al Base Alloy IC6%IC6合金NiCoCrAlY涂层在制造过程中的修复研究

    Institute of Scientific and Technical Information of China (English)

    宋尽霞; 李树索; 肖程波; 闻立时; 韩雅芳

    2002-01-01

    研究了适用于IC6合金的NiCoCrAlY涂层在制造过程中的修复对涂层本身及IC6合金基体的显微组织和力学性能的影响.结果表明,与原始态涂层相似,修复态涂层通过扩散层与基体紧密结合,涂层/基体界面处没有任何孔洞和裂缝,各元素在涂层、基体之间存在明显的浓度梯度.而且涂层修复对IC6合金的显微组织和力学性能均没有明显影响.经过1100℃/90MPa持久试验后,原始态涂层和修复态涂层与IC6合金基体之间都发生了明显的互扩散,涂层中Mo含量上升到16%(质量分数,下同)左右,而Cr和Co含量下降至5%左右,但涂层仍然与合金基体结合紧密.因此,NiCoCrAlY涂层在制造过程中的修复是可行的.

  9. Study on the cutting of self-fluxing alloy of Ni-Cr-WC systems. Ni-Cr-WC kei jiyo gokin yosha himaku no sessaku kako ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Inui, Y.; Hayami, T.; Kubohori, T.; Ikuta, T. (Kinki University, Osaka (Japan). Faculty of Science and Technology)

    1991-03-31

    In this paper, to investigate the cutting of sprayed self-fluxing alloy films of Ni-Cr-WC system containing 35 and 50%WC-Co composite grains in the Ni-Cr matrix, cutting tests by the lathe turning method were performed using CBN tools containing either oxide or carbonitride systems as a binder. Self-fluxing alloy films with about 2mm thichness, which were sprayed on the surface of a cylindrical substrate made of low carbon steel, were used as cutting materials. The wear was increased rapidly at the early stage of cutting, but this was changed to the gradual increasing level after about 30 seconds of cutting. The tool was subject to the abrasive action in cutting, and was fractured when CBN content was low. The CBN tool containing oxide system was found most suitable for cutting of these alloys. The variation in resistance to cutting was observed at the early stage, but this was disappeared after 90 seconds. The roughness of the cutting surface was decreased with cutting time. 8 refs., 10 figs., 2 tabs.

  10. MT genetic engineering bacteria for treatment of Cd, Ni in waste water%MT基因工程菌去除污水中Cd、Ni

    Institute of Scientific and Technical Information of China (English)

    张弛; 马青兰

    2012-01-01

    Performance of a new URB (upflow-refluence-biomembrane) reactive column using MT (metallothionein) genetic engineering bacteria for treatment of heavy metal element as Cd, Ni in waste water was studied. The effect of filler such as active carbon, haydite, core carbon and aquamats ecobase on removal of Cd and Ni is also discussed. For all supported MT-genetic engineering bacteria fillers packed in column, the removal rate is all higher than 43%. For aquamats ecobase packing, the removal rate of Cd and Ni can reach up to 99.4% and 85. 2% respectively, indicating that aquamats ecobase should be the most engineering filler studied. Under the conditions: flow rate 2 L · h-1. pH 9 in influent, reaction temperature 35℃, using URB reactive column and aquamats ecobase as filler, effect of heavy metal load-rate on the removal of Cd and Ni was investigated. The results showed that the optimum heavy metal load-rate for the URB reactor is 0. 481 mg ·mg-1. At the conditions: quiescence immersing aquamats ecobase filler in the 10% MT-genetic engineering bacteria liquid for 24 h, influent concentration of Cd2+ , Ni2+ 100 mg · L-1, effect of reactive column temperature on the removal of Cd and Ni was also studied. The results showed that the optimum temperature is 35℃. The results demonstrate that MT-genetic engineering bacteria is of good compatibility and tolerability to Cd and Ni. The combination process of URB-reactor with MT-genetic engineering bacteria could be used for effective removal of heavy metal contaminant in waste water.

  11. NiP:Mn as a potential magnetic contacting material to Cd1-xMnxTe

    International Nuclear Information System (INIS)

    Injection of spin-polarized current into spintronic devices is a challenge to the semiconductor physicists and technologists. II-VI compound semiconductors can act as the spin aligner on the top of GaAs light emitting diode. However, II-VI compound semiconductor like Cd1-xMnxTe is still suffering from contacting problem. Application of electroless deposited magnetic NiP:Mn contact would enhance efficient current injection into Cd1-xMnxTe than the standard gold contact. A technique for electroless deposition of NiP:Mn on Cd1-xMnxTe have been described here. The electronic and magnetic properties of the contact material NiP:Mn and the contact performance of NiP:Mn relative to evaporated gold have been evaluated. The contact fulfills the requirements of resistivity and ferromagnetism for application to Cd1-xMnxTe.

  12. RELATIONSHIPS BETWEEN FRACTIONATIONS OF Pb, Cd, Cu, Zn AND Ni AND SOIL PROPERTIES IN URBAN SOILS OF CHANGCHUN, CHINA

    Institute of Scientific and Technical Information of China (English)

    GUO Ping; XIE Zhong-lei; LI Jun; KANG Chun-li; LIU Jian-hua

    2005-01-01

    An extensive soil investigation was conducted in different domains of Changchun to disclose the fractionations of Pb, Cu, Cd, Zn and Ni in urban soils. Meanwhile correlation analysis and multiple stepwise regressions were used to define relationships between soil properties and metal fractions and the chief factors influencingthe fractionation of heavy metals in the soils. The results showed that Pb, Ni and Cu were mainly associated with the residual and organic forms; most of Cd was concentrated in the residual and exchangeable fractions. Zn in residual and carbonate fraction was the highest. The activities of the heavy metals probably declined in the following order: Cd, Zn,Pb, CuandNi. The chemical fractions of heavy metals in different domains in Changchun City were of significantly spatial heterogeneity. Soil properties had different influences on the chemical fractions of heavy metals to some extent and the main factors influencing Cd, Zn, Pb, Cu and Ni fractionation and transformation were apparently different.

  13. Photo-ESR and optical studies of Cr photoionization transition in CdZnSe:Cr crystals

    Science.gov (United States)

    Swiatek, K.; Godlewski, M.; Surkova, T. P.

    2004-02-01

    Photoionization transitions of chromium ions in CdxZn1-xSe:Cr bulk crystals (0 x 0.3) were studied in wide temperature range (4-300 K). By monitoring changes of the Cr1+ electron spin resonance signal under external illumination, we are able to determine energies of Cr2+ Cr1+ + hVB transition in different CdxZn1-xSe host crystals. At low temperature we observe metastable population of photo-excited Cr1+ centres.

  14. [THE COMBINATION OF EXPRESSION OF MARKERS CR1 AND CR2 (CD35/CD21) IN DIAGNOSTIC OF B-CELL LYMPHOPROLIFERATIVE DISEASES].

    Science.gov (United States)

    Chibisova, O N; Burtsev, D V; Galstian, K M; Lugovskaia, G I

    2015-04-01

    The study was carried out to analyze rate of expression of antigens CD35 and CD21 in norm and under different forms of B-cell lymphoproliferative diseases. The level of average intensity of fluorescence of antigens CD35, CD21 and CD200 is compared for different groups of patients with B-cell lymphoproliferative diseases. The established patterns of expression of antigens CD35 and CD21 under B-cell lymphoproliferative diseases permit considering expression of the given markers as a characteristic of differential diagnostic. PMID:26189291

  15. Microstructure and Mechanical Properties of High-Alloyed 23Cr-5Mn-2Ni-3Mo Cast Steel / Mikrostruktura I Właściwości Mechaniczne Wysokostopowego Staliwa 23Cr-5Mn-2Ni-3Mo

    Directory of Open Access Journals (Sweden)

    Kalandyk B.

    2015-12-01

    Full Text Available The article presents the microstructure and mechanical properties of cast duplex stainless steel type 23Cr-5Mn-2Ni-3Mo. It has been shown that the structure of the tested cast steel is composed of ferrite enriched in Cr, Mo and Si, and austenite enriched in Mn and Ni. In the initial state, at the interface, precipitates rich in Cr and Mo were present. A high carbon content (0.08%C in this cast steel indicates that probably those were complex carbides of the M23C6 type and/or σ phase. Studies have proved that the solution annealing conducted at 1060°C was not sufficient for their full dissolution, while at the solutioning temperature of 1150°C, the structure of the tested material was composed of ferrite and austenite.

  16. Monotonic and Cyclic Behavior of DIN 34CrNiMo6 Tempered Alloy Steel

    Directory of Open Access Journals (Sweden)

    Ricardo Branco

    2016-04-01

    Full Text Available This paper aims at studying the monotonic and cyclic plastic deformation behavior of DIN 34CrNiMo6 high strength steel. Monotonic and low-cycle fatigue tests are conducted in ambient air, at room temperature, using standard 8-mm diameter specimens. The former tests are carried out under position control with constant displacement rate. The latter are performed under fully-reversed strain-controlled conditions, using the single-step test method, with strain amplitudes lying between ±0.4% and ±2.0%. After the tests, the fracture surfaces are examined by scanning electron microscopy in order to characterize the surface morphologies and identify the main failure mechanisms. Regardless of the strain amplitude, a softening behavior was observed throughout the entire life. Total strain energy density, defined as the sum of both tensile elastic and plastic strain energies, was revealed to be an adequate fatigue damage parameter for short and long lives.

  17. Corrosion Performance of Fe-Cr-Ni Alloys in Artificial Saliva and Mouthwash Solution

    Directory of Open Access Journals (Sweden)

    J. Porcayo-Calderon

    2015-01-01

    Full Text Available Several austenitic stainless steels suitable for high temperature applications because of their high corrosion resistance and excellent mechanical properties were investigated as biomaterials for dental use. The steels were evaluated by electrochemical techniques such as potentiodynamic polarization curves, cyclic polarization curves, measurements of open circuit potential, and linear polarization resistance. The performance of steels was evaluated in two types of environments: artificial saliva and mouthwash solution at 37°C for 48 hours. In order to compare the behavior of steels, titanium a material commonly used in dental applications was also tested in the same conditions. Results show that tested steels have characteristics that may make them attractive as biomaterials for dental applications. Contents of Cr, Ni, and other minor alloying elements (Mo, Ti, and Nb determine the performance of stainless steels. In artificial saliva steels show a corrosion rate of the same order of magnitude as titanium and in mouthwash have greater corrosion resistance than titanium.

  18. Dynamic Recrystallization Behavior of a Fe-Cr-Ni Super-Austenitic Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    A. Hoseini Asli; A. Zarei-Hanzaki

    2009-01-01

    The super-austenitic stainless steels are extensively utilized in the seamless tubes production for oil extraction industries. Due to the importance of thermo-mechanical processing in the production of these tubes, the dynamic recrystallization (DRX) characteristics of a Cr-Ni super austenitic stainless steel (1.4563) were investigated in the present study. This was performed using the hot compression testing method in the temperature range of 950-1150℃ and the strain rate of 10~(-3)-10~(-1)s~(-1). The initiation and evolution of DRX were examined through microstructural analysis. The results indicated that the recrystallized grain formed a necklace type structure at the prior austenite grain boundaries at higher strain rates. In addition, DRX nucleation occurs by bulging and successive strain induced boundary migration (SIBM).

  19. Wear and Corrosion Behavior of CoNiCrAlY Bond Coats

    Science.gov (United States)

    Rathod, W. S.; Khanna, A. S.; Rathod, R. C.; Sapate, S. G.

    2014-07-01

    The present study focusses on the wear and microstructural properties of CoNiCrAlY coatings fabricated on AISI 316L stainless steel substrate by using the (HVOF) and (CGDS) methods. A triobiological test was performed on the samples in order to understand the wear behaviour of thermally sprayed coatings. The microstructures of as-sprayed and worn out coatings were investigated by scanning electron microscopy. Coating hardness measurements were performed with nanoindentation. HVOF coating revealed lower hardness value in comparison with CGDS. Studies depicted better wear resistance of the CGDS sprayed with He, when compared to CGDS N2 and HVOF processing. Potentiodynamic polarization curves and tafel extrapolation experiments were carried at 7.5 pH value using 3.5 % NaCl as an electrolyte. Electrochemical studies depicted better corrosion resistance of the He processed coating when compared to N2 and HVOF processing.

  20. Laser Surface Remelting of Medium Ni-Cr Infinite Chilling Cast Iron Roll

    Institute of Scientific and Technical Information of China (English)

    YAO Jian-hua; ZHANG Qun-li; XIE Song-jing

    2004-01-01

    Laser surface remelting of medium Ni-Cr infinite chilling cast iron was performed with a continuous wave CO2 laser beam with the power of 7 KW under the argon shielding. The microstructural analysis of the laser remelted layer by optical microscope shows that the laser remelted layer consists of three zones, which is the melting zone, the transition zone and the heat affected zone. The size of the dendrite of the melting zone is only in the 1/10 to 1/30 range of that of the substrate. The distribution of the hardness of the laser remelted layer was detected, and the carrying capacity of rolling steel was also field-tested. The results show that both the hardness of the remelted layer and the carrying capacity all increase,especially, the carrying capacity was 50% increased compared with the substrate.

  1. Laser Surface Remelting of Medium Ni-Cr Infinite Chilling Cast Iron Roll

    Institute of Scientific and Technical Information of China (English)

    YAOJian-hua; ZHANGQun-li; XIESong-jing

    2004-01-01

    Laser surface remelting of medium Ni-Cr infinite chilling cast iron was performed with a continuous wave CO2 laser beam with the power of 7 KW under the argon shielding. The microstructural analysis of the laser remelted layer by optical microscope shows that the laser remelted layer consists of three zones, which is the melting zone, the transition zone and the heat affected zone. The size of the dendrite of the melting zone is only in the 1/10 to 1/30 range of that of the substrate. The distribution of the hardness of the laser remelted layer was detected, and the carrying capacity of rolling steel was also field-tested. The results show that both the hardness of the remelted layer and the carrying capacity all increase, especially, the carrying capacity was 50% increased compared with the substrate.

  2. High temperature damping behavior of plasma sprayed NiCoCrAlY coatings

    Science.gov (United States)

    Khor, K. A.; Chia, C. T.; Gu, Y. W.; Boey, F. Y. C.

    2002-09-01

    There is a trend to design the turbine coating and the substrate as in integral, layered, engineering assembly. Under the harsh environment of the turbine engine, a failure in one component can quickly lead to failure in other components. Materials that are used in structural applications are prone to mechanical vibration, which, when not attenuated, will lead to fatigue of components and shortening of life cycle. Therefore, it is necessary to examine the thermal stability and dynamic mechanical properties of coatings under dynamic conditions. In addition to these noise reduction and vibration amplitude control motivated objectives, however, mechanical energy dissipation processes also find intrinsic applications in cases for which a thorough understanding of the mechanisms responsible for the damping response of the material is required. This article describes the damping behavior and mechanisms that exist in plasma sprayed NiCoCrAlY coatings.

  3. Precipitation hardening in a 12%Cr-9%Ni-4%Mo-2%Cu stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Haettestrand, Mats; Nilsson, Jan-Olof; Stiller, Krystyna; Liu Ping; Andersson, Marcus

    2004-02-23

    A combination of complementary techniques including one-dimensional and three-dimensional atom probe, energy-filtered transmission electron microscopy and conventional transmission electron microscopy has been used to assess the precipitation reactions at 475 deg. C in a 12%Cr-9%Ni-4%Mo-2%Cu precipitation hardening stainless steel. The continuous hardening up to at least 1000 h of ageing was attributed to a sequence of precipitation reactions involving nickel-rich precipitates nucleating at copper clusters followed by molybdenum-rich quasicrystalline precipitates and nickel-rich precipitates of type L1{sub 0}. An estimate of the relative contributions to the strength increment during tempering based on measurements of particle densities was performed. Nickel-rich precipitates were found to play the most important role up to about 40 h of ageing after which the effect of quasicrystalline particles became increasingly important.

  4. Random cyclic constitutive models of 0Cr18Ni10Ti pipe steel

    International Nuclear Information System (INIS)

    Experimental study is performed on the random cyclic constitutive relations of a new pipe stainless steel, 0Cr18Ni10Ti, by an incremental strain-controlled fatigue test. In the test, it is verified that the random cyclic constitutive relations, like the wide recognized random cyclic strain-life relations, is an intrinsic fatigue phenomenon of engineering materials. Extrapolating the previous work by Zhao et al, probability-based constitutive models are constructed, respectively, on the bases of Ramberg-Osgood equation and its modified form. Scattering regularity and amount of the test data are taken into account. The models consist of the survival probability-strain-life curves, the confidence strain-life curves, and the survival probability-confidence-strain-life curves. Availability and feasibility of the models have been indicated by analysis of the present test data

  5. Random cyclic strain-life relations of 0Cr18Ni10Ti pipe steel

    International Nuclear Information System (INIS)

    Experimental study is performed on the random cyclic strain-life relations of the new pipe steel, 0Cr18Ni10Ti, by strain-controlled fatigue tests. Probabilistic models for characterizing the relations are presented on a basis of the Coffin-Manson strain-life equation. Three kinds of effects on probabilistic assessments are taken into account, which are the scattering regularity, the amount, and the combined effect of scattering regularity and the amount of the test data. With respect to these effects, the models are consisted of three kinds of probabilistic curves, i.e. the survival probability-strain-life curves, the confidence-based strain-life curves, and the probability and confidence-based strain-life curves. Availability and feasibility of the models are indicated by an analysis to the test results

  6. Energy levels and radiative rates for transitions in Cr-like Co IV and Ni V

    CERN Document Server

    Aggarwal, K M; Karpuškienė, R; Keenan, F P; Kisielius, R; Stancalie, V

    2015-01-01

    We report calculations of energy levels and radiative rates ($A$-values) for transitions in Cr-like Co IV and Ni V. The quasi-relativistic Hartree-Fock (QRHF) code is adopted for calculating the data although GRASP (general-purpose relativistic atomic structure package) and flexible atomic code (FAC) have also been employed for comparison purposes. No radiative rates are available in the literature to compare with our results, but our calculated energies are in close agreement with those compiled by NIST for a majority of the levels. However, there are discrepancies for a few levels of up to 3\\%. The $A$-values are listed for all significantly contributing E1, E2 and M1 transitions, and the corresponding lifetimes reported, although unfortunately no previous theoretical or experimental results exist to compare with our data.

  7. Corrosion behavior of NiCrBSi coatings deposited by HVOF spraying

    Institute of Scientific and Technical Information of China (English)

    赵卫民; 王勇; 吴开源; 薛锦

    2003-01-01

    The corrosion resistance of NiCrBSi coating deposited on steel substrate by HVOF was examined using electrochemical tests and immersion tests so as to offer an experimental basis to expand a promising applied field of HVOF in aqueous medium, comparing with those of coatings deposited by oxyacetylene flame spraying and flame cladding. The results show that the general corrosion rate of HVOF sprayed coatings is quite bigger than that of clad coatings, but it is less sensitive to local corrosion. There is less and smaller porosity in the coatings deposited by HVOF than that in flame sprayed coatings. The effects of porosity on the corrosion current density was indistinctive, but the existence of large amount of defects in the coatings damaged the cohesion of the coatings, causing the metallic particles drop off from the coatings under the influence of corrosive medium. Improving the quality and reducing the porosity of coatings is the key to get the coatings with high corrosion resistance.

  8. Synthesis of ceria based superhydrophobic coating on Ni20Cr substrate via cathodic electrodeposition.

    Science.gov (United States)

    Pedraza, F; Mahadik, S A; Bouchaud, B

    2015-12-21

    In this work, superhydrophobic cerium oxide coating surface (111) with dual scale texture on Ni20Cr substrate is obtained by combination of electropolishing the substrate and subsequent cathodic electrodeposition and long-term UVH surface relaxation. To form hierarchical structures of CeO2 is controllable by varying the substrate roughness, and electropolishing period. The results indicated that at the optimal condition, the surface of the cerium oxide coating showed a superhydrophobicity with a great water contact angle (151.0 ± 1.4°) with Gecko state. An interface model for electropolishing of substrate surface in cerium nitrate medium is proposed. We expect that this facile process can be readily and widely adopted for the design of superhydrophobic coating on engineering materials. PMID:26562006

  9. Induced effects in Fe-Ni-Cr austenitic alloys by electron irradiation

    International Nuclear Information System (INIS)

    Materials behaviour under high energetic particles exposure has to be know for technological aspects, but also for microscopic material state physics. Large macroscopic investigations have been developed but reliability with theoretical calculations or fundamental physics measurements is not clear. We present four experimental procedures in order to characterize austenitic Fe-Ni-Cr synthetic alloys in the atomic scale. First, results obtained about vacancy and interstitial, after electrical resistivity measurements and monoenergetical or classical positron annihilation process, are discussed. Then, defects clustering and microstructural evolution is investigated using positron lifetime measurements and high resolution electronic microscopy. In this study, special care has been taken to understand the composition effect as a function of the irradiation conditions

  10. Welded joint properties of 08Cr2.25Mo1NiNb type steel

    International Nuclear Information System (INIS)

    The results are given of a study into the effect of the chemical composition on the mechanical and structural properties of welded joint of steel 08Cr2.25Mo1NiNb. The welded joints were obtained by manual arc welding using coated electrodes. For assessing short-term strength and plastic properties, tensile tests at normal temperature, notch toughness tests, hardness measurements and bending tests were conducted. The welded joint microstructure was also analysed. The minimal values of the yield point can be obtained in welded joints of melts with the Nb content at a level of the stabilization ratio. The highest hardness values were obtained in the welding metal ranges, which, however, does not negatively affect the plastic properties of the joint. Lower values of notch toughness were found for welding metals with higher carbon content. (M.S.)

  11. Electrochemical investigations of Cr-Ni-Mo stainless steel used in urology

    Science.gov (United States)

    Przondziono, J.; Walke, W.

    2011-05-01

    The influence of chemical passivation process on physical and chemical characteristics of samples made of X2CrNiMo 17-7-2 steel with differentiated hardening, in the solution simulating the environment of human urine was analysed in the study. Wire obtained in cold drawing process is used for the production of stents and appliances in urological treatment. Proper roughness of the surface was obtained through mechanical working - grinding (Ra = 0,40 μn) and electrochemical polishing (Ra = 0,12 μn). Chemical passivation process was carried out in 40% solution of HN03 within 60 minutes in the temperature of 65°C. The tests of corrosion resistance were made on the ground of registered anodic polarisation curves and Stern method. For evaluation of phenomena occurring on the surface of tested steel, electrochemical impedance spectroscopy (EIS) was applied.

  12. Conversion of stacking fault tetrahedra to voids in electron irradiated Fe-Cr-Ni

    Science.gov (United States)

    Kojima, S.; Sano, Y.; Yoshiie, T.; Yoshida, N.; Kiritani, M.

    1986-11-01

    Electron irradiations of the austenitic Fe-13Cr-14Ni alloy were performed with a high voltage electron microscope at temperatures between room temperature and 650 K. Formation of stacking fault tetrahedra, voids and dislocation loops was observed as vacancy clusters. At the lower temperatures, the dominant vacancy clusters were tetrahedra and at the higher temperatures, voids were dominant. In the temperature range at which both tetrahedra and voids were coexistent, conversion of tetrahedra to voids were observed. These results are interpreted as the preferable nucleation of voids at the site of tetrahedra. Local effects of dilatation field at the corner of tetrahedra and the segregation of solute atoms are considered to enhance the nucleation. Clustered defects which are considered to be stacking fault tetrahedra that are formed with D-T fusion neutrons in SUS 316 stainless steel are suggested as the preferable site for void nucleation.

  13. THE CHARACTERISTICS OF OXIDE SCALE FORMED ON LOW PRESSURE PLASMA SPRAYED NiCrAIY COATING IN THE PRESENCE OF 5% WATER VAPOR

    Institute of Scientific and Technical Information of China (English)

    J.S.Yu; C.G.Zhou; H.B.Xu; S.K.Gong

    2002-01-01

    The oxidations of low pressure plasma sprayed (LPPS) NiCrAlY coating on nickelbase superalloy were studied at 1050C in flows of O2, and mixture of O2 and 5%H2 Ounder atmospheric pressure. Oxide formed on the surface of LPPS NiCrAlY coatingafter oxidation at 1050℃ in pure O2 consisted of NiCr2 O4, whereas oxide formed onthe surface of LPPS NiCrAlY coating after oxidation at 1000℃ in a mixture of O2 and5%H2 O is mainly composed of NiO. The effect of water vapor on the characteristicsof the oxide scale is attributed to the increase in Ni cation transport.

  14. Welding Procedure of 06Cr19Ni10 and Q345R in Using Shielded Metal Arc Welding%06Cr19Ni10与Q345R焊条电弧焊焊接工艺

    Institute of Scientific and Technical Information of China (English)

    王立跃; 王小平

    2013-01-01

    The main problems in welding 06Cr19Ni10 and Q345R steel is that when adopting multilayer multichannel welding, by the side of the Q345R steel (weld root of weld toe online), the lack of fusion and slag produce easily. By participating in drum welding test, welding technology preparation and drum manufacturing of a heat recovery boiler, the weldability of 06Cr19Ni10 steel and Q345R steel, the causes of weld defects, the process measures of avoiding defects and how repair after the the appearance of defects were investigated. Then, the welding process and methods for the dissimilar steel 06Crl9Nil0 and Q345R were expounded%06Cr19Ni10钢与Q345R钢焊接的主要问题是,多层多道焊时,靠Q345R钢的一侧(焊缝根部的焊趾线上)易产生未熔合与夹渣.作者通过参与一台余热锅炉锅筒的焊接试验、焊接工艺编制与锅筒制造,研究06Cr19Ni10与Q345R钢的焊接及焊接缺陷产生的原因、避免缺陷产生的工艺措施以及产生缺陷后如何进行返修等几个方面.同时阐述了06Cr19Ni10与Q345R异种钢的焊接工艺和方法.

  15. Study of the interactions between irradiation and chemical order effects in ternary alloys Ni-Cr-Fe; Etude des interactions entre effets d`irradiation et effets d`ordre chimique dans les alliages ternaires Ni-Cr-Fe

    Energy Technology Data Exchange (ETDEWEB)

    Frely, E

    1997-12-31

    Because of its resistance to corrosion even under stress, the alloy 69 (nickel-based alloy with a chemically disordered F.c.c. structure) is a promising material for application in some of the inner parts of nuclear reactor. However, the eventual formation of an ordered NI{sub 2}Cr superstructure under irradiation or thermal ageing might diminish its performances. We have studied the binary model alloy Ni-Cr33at.% as well as the ternary alloys Ni-Cr3at.%-Fe5cat.% and Ni-Cr32at.%-Fe10at.%, the last one having a chemical composition similar to that of the industrial alloy. After irradiation experiments with 2.5 MeV electrons in the 300-500 deg C temperature range, all the model alloys show the Ni{sub 2}Cr superstructure. The samples irradiated at fluences between 2 and 8. 10 d.p.a. have been characterized by X-ray and neutron diffraction. The superlattice reflexions and the ordered domains have been observed by electron microscopy. The critical temperature of the order-disorder transformation, measured under 1 MeV electron irradiation, decreases linearly with iron content. The evolution of the chemical corder has been traced by means of in situ resistivity measurements. We have used the pair exchange based Dienes model of ordering kinetics for studying the long range order S (S between 0.5 and 0.8 after irradiation). The iron seems to remain in disorder in the sublattices. The similarity of the results under thermal ageing and under irradiation shows that the main effect of the electronic irradiation is to accelerate ordering. Under both treatments increasing the iron content or the dislocation density reduce the ordering kinetics. However, this effect is not sufficient to explain the lack of order in alloy 690 after a fluence of 1 d.p.a. (author). 95 refs.

  16. Aging of a cast 35Cr-45Ni heat resistant alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sustaita-Torres, Ireri A., E-mail: ireri.sustaita@gmail.com [Unidad Academica de Ingenieria, Universidad Autonoma de Zacatecas, 98000 Zacatecas (Mexico); Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, 66450 San Nicolas de los Garza (Mexico); Haro-Rodriguez, Sergio, E-mail: haros907@hotmail.com [Unidad Academica de Ingenieria, Universidad Autonoma de Zacatecas, 98000 Zacatecas (Mexico); Guerrero-Mata, Martha P., E-mail: martha.guerreromt@uanl.edu.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, 66450 San Nicolas de los Garza (Mexico); Garza, Maribel de la, E-mail: maribeldelagarza@yahoo.com.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, 66450 San Nicolas de los Garza (Mexico); Valdes, Eduardo, E-mail: eduardo.valdes.57@gmail.com [Instituto Tecnologico de Saltillo, 25280 Saltillo (Mexico); Deschaux-Beaume, Frederic, E-mail: deschaux@iut-nimes.fr [Mechanical and Civil Engineering Laboratories, Universite de Montpellier 2, IUT Nimes, 30907 Nimes (France); and others

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer The as-cast microstructure is made of an austenitic matrix and primary carbides. Black-Right-Pointing-Pointer The carbides are of two different types: Cr- and Nb-rich. Black-Right-Pointing-Pointer The microstructure changes during aging. Black-Right-Pointing-Pointer These microstructural changes result in the degradation of mechanical properties. - Abstract: The microstructural evolution during aging and its effect on the mechanical properties of a centrifugally cast 35Cr-45Ni heat resistant alloy was studied by means of optical and electron microscopy, and by mechanical testing in samples aged in air at 750 Degree-Sign C for a period of time of up to 1000 h. The as-cast microstructure consisted of an austenitic matrix and a network of two types of primary carbides that were identified as NbC and M{sub 7}C{sub 3} by their light and dark tones when viewed in backscattered electron mode in a scanning electron microscope. Aging promoted the occurrence of different phenomena such as the transformation of primary M{sub 7}C{sub 3} to M{sub 23}C{sub 6} carbides, precipitation of secondary M{sub 23}C{sub 6} carbides and the transformation of NbC to Nb{sub 3}Ni{sub 2}Si. It was found that aging promoted an increase in Vickers microhardness of more than 50%, the increment in tensile strength of around 20% and the reduction in ductility of close to 70%.

  17. Temporal Evolution of the Nanostructure and Phase Compositions in a Model Ni-Al-Cr Alloy

    Science.gov (United States)

    Sudbrack, Chantal K.; Yoon, Kevin E.; Seidman, David N.; Seidman, David N.

    2006-01-01

    In a Ni-5.2 Al-14.2 Cr at.% alloy with moderate solute supersaturations and a very small gamma/gamma prime lattice parameter misfit, the nanostructural and compositional pathways during gamma prime(L12) precipitation at 873 K are investigated using atom-probe tomography, conventional transmission electron microscopy, and hardness measurements. Nucleation of high number densities (N(sub v) greater than 10(sup 23) per cubic meters) of solute-rich precipitates (mean radius = [R] = 0.75 nm), with a critical nucleus composition of Ni-18.3 plus or minus 0.9 Al-9.3 plus or minus 0.7 Cr at.%, initiates between 0.0833 and 0.167 h. With increasing aging time (a) the solute concentrations decay in spheroidal precipitates ([R] less than 10 nm); (b) the observed early-stage coalescence peaks at maximum N(sub v) in coincidence with the smallest interprecipitate spacing; and (c) the reaction enters a quasi-stationary regime where growth and coarsening operate concomitantly. During this quasi-stationary regime, the c (face-centered cubic)-matrix solute supersaturations decay with a power-law dependence of about -1/3, while the dependencies of [R] and N(sub v) are 0.29 plus or minus 0.05 and -0.64 plus or minus 0.06 at a coarsening rate slower than model predications. Coarsening models allow both equilibrium phase compositions to be determined from the compositional measurements. The observed early-stage coalescence is discussed in further detail.

  18. Synthesis and photoluminescence of Cr-, Ni-, Co-, and Ti-doped ZnSe nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Huy, Bui The [Anastro Laboratory, Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of); Nhatrang Institute of Technology and Research Application, 2 Hungvuong, Nhatrang (Viet Nam); Seo, Min-Ho; Kumar, Avvaru Praveen [Anastro Laboratory, Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of); Jeong, Hyuk [Department of Chemistry, Sookmyung Women’s University, Seoul 140-742 (Korea, Republic of); Lee, Yong-Ill, E-mail: yilee@changwon.ac.kr [Anastro Laboratory, Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of)

    2014-03-05

    Highlights: • The chain length, structure of surfactants operated the size nanoparticles. • Ni{sup 2+}, Co{sup 2+}, Cr{sup 3+}, and Ti{sup 3+} did not create any new centers in the structure of ZnSe. • Doping may have influenced the nanoparticles size because of the Zn replacement. • The TM ions change in ligand field caused the influence on fluorescence intensity. -- Abstract: We developed a facile strategy to synthesize transition metal (TM; Ni, Cr, Co, and Ti)-doped ZnSe nanoparticles (NPs) in aqueous media using a chemical co-precipitation method. Co-precipitation was performed in the presence of one of four different surfactants, namely mercaptoacetic acid (MAA), 3-mercaptopropionic acid (MPA), thioglycerol (TGC), or (3-mercaptopropyl) trimethoxysilane (MPTMS). Surface morphology, chemical, and crystalline properties of the TM-doped ZnSe NPs were studied by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Optical features were characterized by UV–visible and photoluminescence spectroscopies. The influence of various experimental parameters, including the amount of TM and the ratio of precursors, as well as different types of surfactants on the photoluminescence properties of TM-doped ZnSe NPs was investigated systematically. TM-doped ZnSe NPs were excited in the UV region and exhibited photoluminescence in the visible region. Intensity was affected by the concentration of the TM. The results showed that MPA had a stronger influence on photoluminescence than MAA, TGC, and MPTMS. The photoluminescence intensity of TM-doped ZnSe NPs was 30% higher than that of undoped ZnSe NPs.

  19. Microstructure and Mechanical Properties of Electromagnetic Centrifugal Cast 1Cr25Ni20Si2 Tube Blank

    Institute of Scientific and Technical Information of China (English)

    QIU Yi-qing; JIA Guang-lin; LIU Xiang-hua; WANG Guo-dong

    2006-01-01

    1Cr25Ni20Si2 tube blank centrifugally cast in a steady magnetic field was investigated. The results indicated that the solidification structure and the mechanical properties of the blank can be improved remarkably by electromagnetic stirring, and seamless tube can be manufactured from such blanks.

  20. Role of HVOF-spray NiCr coatings to control high temperature oxidation of some boiler steels

    Energy Technology Data Exchange (ETDEWEB)

    Kaushal, G. [RIMT-Institute of Engineering and Technology, Mandi Gobind Garh (India); Singh, H. [BBSB Engineering College, Fatehgarh Sahib (India); Prakash, S. [Indian Inst. of Technology, Roorkee (India)

    2008-07-01

    A study was carried out to determine the role of HVOF-spray Ni-20Cr coatings to enhance high temperature oxidation resistance of T22 and 347H boiler steels. Ni-20Cr coatings were deposited on the boiler steels. Subsequently high temperature oxidation behavior of these coatings was investigated by laboratory tests at an elevated temperature of 900 C under cyclic conditions.These coatings were also subjected to a boiler environment at an elevated temperature of 700 C under cyclic conditions to ascertain their erosion-corrosion behaviour. Thermogravimetric data was taken after each cycle to formulate the oxidation, as well as, erosion-corrosion kinetics. The specimens were also physically examined after each cycle to notice any macrographic physical changes, spallation tendency of their oxide scales etc. The exposed specimens were examined using scanning electron microscopy and Energy Dispersive Spectroscopy (SEM/EDS) analysis. It was observed that oxidation rate was subsequently low in the coated substrates as compare to uncoated steels. It was observed that Ni-20Cr coating on 347H boiler substrate showed the maximum oxidation resistance. Moreover, both the steels showed better resistance to erosion-corrosion in actual boiler conditions after the application of Ni-20Cr coating. (orig.)

  1. Electrochemical Study of Ni20Cr Coatings Applied by HVOF Process in ZnCl2-KCl at High Temperatures

    Directory of Open Access Journals (Sweden)

    J. Porcayo-Calderón

    2014-01-01

    Full Text Available Corrosion behavior of Ni20Cr coatings deposited by HVOF (high velocity oxygen-fuel process was evaluated in ZnCl2-KCl (1 : 1 mole ratio molten salts. Electrochemical techniques employed were potentiodynamic polarization curves, open circuit potential, and linear polarization resistance (LPR measurements. Experimental conditions included static air and temperatures of 350, 400, and 450°C. 304-type SS was evaluated in the same conditions as the Ni20Cr coatings and it was used as a reference material to assess the coatings corrosion resistance. Coatings were evaluated as-deposited and with a grinded surface finished condition. Results showed that Ni20Cr coatings have a better corrosion performance than 304-type SS. Analysis showed that Ni content of the coatings improved its corrosion resistance, and the low corrosion resistance of 304 stainless steel was attributed to the low stability of Fe and Cr and their oxides in the corrosive media used.

  2. Influence of the chemical composition of rapidly quenched amorphous alloys (Ni, Fe, Cr)-B-Si on its crystallization process

    Science.gov (United States)

    Elmanov, G.; Dzhumaev, P.; Ivanitskaya, E.; Skrytnyi, V.; Ruslanov, A.

    2016-04-01

    This paper presents results of research of the structure and phase transformations during the multistage crystallization of the metallic glasses with the compositions Ni71,5Cr6,8Fe2,7B11,9Si7,1 and Ni63,4Cr7,4Fe4,3Mn0,8B15,6Si8,5 labeled as AWS BNi-2 according to American Welding Society. Differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX) were used as experimental research methods. The influence of the alloys chemical composition (boron, manganese and iron) on the temperatures and the exothermic heat effects of phase transformations, as well as on the phase composition of alloys at three stages of crystallization was analyzed. We present a thermodynamic explanation of the observed heat effects. It has been shown that manganese has the main influence on the phase transformations temperatures and heat effects in these two alloys. It is also assumed that at the final crystallization stage simultaneously with the formation of phases Ni3B and β1-Ni3Si should occur the nucleation of borides of CrB type with high Cr and low Si content.

  3. Evaluation of Thermocyclic Oxidation Behavior of HVOF-Sprayed NiCrFeSiB Coatings on Boiler Tube Steels

    Science.gov (United States)

    Ramesh, M. R.; Prakash, S.; Nath, S. K.; Sapra, Pawan Kumar; Krishnamurthy, N.

    2011-09-01

    High velocity oxy-fuel (HVOF) spray process has grown into a well-accepted industrial technology for obtaining coatings resistant to significant surface degradation processes. In the present study, HVOF process was used to deposit Ni-based hardfacing NiCrFeSiB alloy powder on kinds of boiler tube steels designated as SA210 grade-A1, SA213-T11, and SA213-T22. The microstructures and several properties of the as-sprayed coatings have been investigated. Thermocyclic oxidation studies were performed in static air at 900 °C. NiCrFeSiB-coated steels showed slow oxidation kinetics and considerably lower weight gains than that of uncoated steels. The superior performance of NiCrFeSiB coatings can be attributed to continuous and protective thin oxide scale of amorphous SiO2 and Cr2O3 formed on the surface of the oxidized coatings. The combined technique of x-ray diffraction, scanning electron microscopy, energy dispersive x-ray analysis, and electron probe microanalysis are used to characterize reaction products of the oxidized surfaces.

  4. NiCr基锅炉管道涂层材料抗高温氧化性能的研究%PERFORMANCE OF HIGH TEMPERATURE OXIDATION RESISTANCE OF NiCr-BASED COATING MATERIALS FOR BOILER TUBES

    Institute of Scientific and Technical Information of China (English)

    丁彰雄; 王群; 詹旺滨

    2003-01-01

    设计及采用亚音速喷涂工艺制备了锅炉管道NiCr-Cr3C2涂层;评价了它的抗高温氧化特征,并与20G锅炉钢及目前广泛使用的NiCrTi涂层进行了对比;采用扫描电镜以及X衍射仪等对氧化产物的形貌和相组成进行了分析,探讨了NiCr-Cr3C2及NiCrTi涂层的抗高温氧化机理.

  5. Biosorption of Cr (Ⅵ), Cr (Ⅲ), Pb (Ⅱ) and Cd (Ⅱ) from Aqueous Solutions by Sargassum wightii and Caulerpa racemosa Algal Biomass

    Institute of Scientific and Technical Information of China (English)

    Narayanaswamy Tamilselvan; Kumar Saurav; Krishnan Kannabiran

    2012-01-01

    Heavy metal pollution is one of the most important environmental problems today.Biosorption is an innovative technology that employs biological materials to accumulate heavy metals from waste water through metabolic process or physicochemical pathways of uptake.Even though several physical and chemical methods are available for removal of heavy metals,currently many biological materials such as bacteria,algae,yeasts and fungi have been widely used due to their good performance,low cost and large quantity of availability.The aim of the present study is to explore the biosorption of toxic heavy metals,Cr(Ⅵ),Cr(Ⅲ),Pb(Ⅱ) and Cd(Ⅱ) by algal biomass obtained from algae Sargassum wightii (brown) and Caulerpa racemosa (green).Biosorption of algal biomass was found to be biomass concentration- and pH-dependent,while the maximal biosorption was found at pH 5.0 and with the metal concentration of 100 mgL-1.S.wightii showed the maximal metal biosorption at the biomass concentration of 25 g L-1,followed by C.racemosa with the maximal biosorption at 30gL1.S.wightii showed 78% biosorption of Cr(Ⅵ),Cr(Ⅲ),Pb(Ⅱ) and Cd(Ⅱ) ions.C.racemosa exhibited 85% biosorption of Cd(Ⅱ) and Cr(Ⅵ),and 50% biosorption of Cr(Ⅲ) and Pb(Ⅱ).The results of our study suggest that seaweed biomass can be used efficiently for biosorption of heavy metals.

  6. EFFECT OF La AND Hf DOPANT ON THE HIGH TEMPERATURE OXIDATION OF CoNiCrAl ALLOYS%La和Hf对CoNiCrAl合金涂层高温氧化行为的影响

    Institute of Scientific and Technical Information of China (English)

    宋鹏; 陆建生; 张德丰; 吕建国; 李德江

    2011-01-01

    对单一添加及同时添加La和Hf的CoNiCrAl合金进行真空高温氧化处理,研究单一添加与同时添加La和Hf对合金表面氧化物生长机制和黏结性能的影响.结果表明:表面抛光的合金在1100℃氧化时,同时添加La和Hf使CoNiCrAl合金在其表面形成了连续均匀的Al2O3,并且具有较好的黏结性能.通过18O追踪原子氧化发现CoNiCrAlLa,CoNiCrAlHf和CoNiCrAlLaHf合金的Al2O3生长均为O2-内扩散为主的生长机制,同时伴随少量的金属离子外扩散.单一添加La和Hf形成的Al2O3表面富集Cr,Co和Ni等,且随Al2O3深度增加而逐渐降低,这些元素促使Al2O3表面形成Ni(Co)Al2O4,从而降低Al2O3的黏结性能.同时添加La和Hf没有改变O2-内扩散为主的生长机制,但Hf能够阻碍La在氧化物/合金界面的富集,减少Ni(Co)Al2O4形成,同时合金表面局部内氧化的钉扎效应提高了Al2O3的黏结性能.%CoNiCrAl alloys are widely used as bond coats for thermal barrier coating (TBC) at high operating temperature for energy conversion systems, especially turbine. However, the effect of reactive element (RE) on the oxidation behavior of CoNiCrAl alloys is still not uniform, thereby limiting the usage of the alloys. To study the effect of co-doped RE, the polished cast CoNiCrAlLa, CoNiCrAlHf and CoNiCrAlLaHf alloys were oxidized at 1100 X2 in vacuum. Growth kinetics and adherence of oxide scales formed on above alloys were studied through comparing mass dynamics curves and tracer oxidation of the alloys. SEM, TG and XRD as well as secondary neutrals mass spectrometry (SNMS) were employed to study the microstructure and growth mechanism of the oxide layers. The results showed that a protective AI2O3 scale formed on the surface of CoNiCrAlLaHf alloy, and the AI2O3 scale showed a good adherence due to a pinning effect of the internal oxidation and less Ni(Co)Al2O4 formation. The Hf could suppress La enrichment at the oxide/alloy interface

  7. Effects of Tantalum on the Temporal Evolution of a Model Ni-Al-Cr Superalloy During Phase Decomposition

    Science.gov (United States)

    Booth, Morrison, Christopher; Seidman, David N.; Noebe, Ronald D.

    2009-01-01

    The effects of a 2.0 at.% addition of Ta to a model Ni-10.0Al-8.5Cr (at.%) superalloy aged at 1073 K are assessed using scanning electron microscopy and atom-probe tomography. The gamma'(Ll2)-precipitate morphology that develops as a result of gamma-(fcc)matrix phase decomposition is found to evolve from a bimodal distribution of spheroidal precipitates, to {001}-faceted cuboids and parallelepipeds aligned along the elastically soft {001}-type directions. The phase compositions and the widths of the gamma'-precipitate/gamma-matrix heterophase interfaces evolve temporally as the Ni-Al-Cr-Ta alloy undergoes quasi-stationary state coarsening after 1 h of aging. Tantalum is observed to partition preferentially to the gamma'-precipitate phase, and suppresses the mobility of Ni in the gamma-matrix sufficiently to cause an accumulation of Ni on the gamma-matrix side of the gamma'/gamma interface. Additionally, computational modeling, employing Thermo-Calc, Dictra and PrecipiCalc, is employed to elucidate the kinetic pathways that lead to phase decomposition in this concentrated Ni-Al-Cr-Ta alloy.

  8. Characterization and oxidation behavior of NiCoCrAlY coating fabricated by electrophoretic deposition and vacuum heat treatment

    Science.gov (United States)

    Li, Zhiming; Qian, Shiqiang; Wang, Wei

    2011-03-01

    Electrophoretic deposition (EPD) was showed to be a feasible and convenient method to fabricate NiCoCrAlY coatings on nickel based supperalloys. The microstructure and composition of the NiCoCrAlY coatings after vacuum heat treatment were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDAX). Isothermal-oxidation test was performed at 1100 °C in static air for 100 h. The results show that the major phases in electrophoretic deposited and vacuum heat treated NiCoCrAlY coating are γ-Ni and γ‧-Ni3Al phases, also there is an extremely small quantity of Al2O3 in the coating. Composition fluctuations occur in the coating and a certain amount of titanium diffuse from the superalloy substrate to the top of the coating during vacuum heat treatment. The oxidation test results exhibit that the oxidation kinetics of this coating has two typical stages. The protective oxide layer is mainly formed in the initial linear growth stage and then the oxide layer hinders further oxidation of the coating in the subsequent parabolic growth stage. The coating can effectively protect the superalloy substrate from oxidation. A certain amount of rutile TiO2 is formed in the coating during oxidation and it is adverse to the oxidation resistance of the coating.

  9. 镍铬烤瓷合金的生物性能%Biological performance of Ni-Cr porcelain alloy

    Institute of Scientific and Technical Information of China (English)

    沈晴昳; 李国强; 钟群

    2009-01-01

    镍铬烤瓷合金的生物学性能与材料所释放的金属离子密切相关.镍铬烤瓷合金所释放的金属离子,尤其是镍、铍等可能导致临近牙周组织和口腔黏膜的炎症反应.体外实验证明,金属过敏反应为多种金属离子对机体免疫系统的影响所致.重铸镍铬烤瓷合金的耐腐蚀性差和细胞毒性大.严格按工艺要求制作的镍铬合金烤瓷修复体生物安全性能良好.镍铬烤瓷合金在口腔内腐蚀过程中释放少量金属离子,刺激局部组织,可能导致邻近组织过敏、变色,但对全身系统无明显毒副作用,无明显遗传毒性或致癌性.%Biological performances of Ni-Cr porcelain alloy are highly correlated with released metallic ions. Released metal ions from Ni-Cr porcelain alloy, particularly Ni, Be can induce inflammation of the adjacent periodontal tissue and oral mucosa. In vitro evidence has indicated that the immune response can be altered by various metal ions. Allergic reactions due to metallic dental restorations have been documented. Ni has especially been identified as being highly allergenic. The cytotoxicity and corrosion level of Ni-Cr porcelain alloy is increased after recasting. The Ni-Cr porcelain alloy produced according to technology requirements has good biological safety. Ni-Cr porcelain alloy released a few of metal ions which might induce allergy and density of adjacent periodontal tissues, for the stimulation effect of these metal ions. There is no evidence to suggest that Ni-Cr porcelain alloy restorations has systemic toxicity or carcinogenic/genotoxic effect to human.

  10. Microstructure and mechanical properties of NiCoCrAlYTa alloy processed by press and sintering route

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, J.C., E-mail: jpereira@uc.edu.ve [Instituto de Tecnología de Materiales, Universidad Politécnica de Valencia, Camino de vera s/n, Valencia, España (Spain); Centro de Investigaciones en Mecánica, Facultad de Ingeniería, Universidad de Carabobo (Venezuela, Bolivarian Republic of); Zambrano, J.C. [Centro de Investigaciones en Mecánica, Facultad de Ingeniería, Universidad de Carabobo (Venezuela, Bolivarian Republic of); Afonso, C.R.M. [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos (UFSCar), São Carlos, SP (Brazil); Amigó, V. [Instituto de Tecnología de Materiales, Universidad Politécnica de Valencia, Camino de vera s/n, Valencia, España (Spain)

    2015-03-15

    Nickel-based superalloys such as NiCoCrAlY are widely used in high-temperature applications, such as gas turbine components in the energy and aerospace industries, due to their strength, high elastic modulus, and high-temperature oxidation resistance. However, the processing of these alloys is complex and costly, and the alloys are currently used as a bond coat in thermal barrier coatings. In this work, the effect of cold press and sintering processing parameters on the microstructure and mechanical properties of NiCoCrAlY alloy were studied using the powder metallurgy route as a new way to obtain NiCoCrAlYTa samples from a gas atomized prealloyed powder feedstock. High mechanical strength and adequate densification up to 98% were achieved. The most suitable compaction pressure and sintering temperature were determined for NiCoCrAlYTa alloy through microstructure characterization. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive spectroscopy microanalysis (EDS) were performed to confirm the expected γ-Ni matrix and β-NiAl phase distribution. Additionally, the results demonstrated the unexpected presence of carbides and Ni–Y-rich zones in the microstructure due to the powder metallurgy processing parameters used. Thus, microhardness, nanoindentation and uniaxial compression tests were conducted to correlate the microstructure of the alloy samples with their mechanical properties under the different studied conditions. The results show that the compaction pressure did not significantly affect the mechanical properties of the alloy samples. In this work, the compaction pressures of 400, 700 and 1000 MPa were used. The sintering temperature of 1200 °C for NiCoCrAlYTa alloy was preferred; above this temperature, the improvement in mechanical properties is not significant due to grain coarsening, whereas a lower temperature produces a decrease in mechanical properties due to high porosity and

  11. Microstructure and mechanical properties of NiCoCrAlYTa alloy processed by press and sintering route

    International Nuclear Information System (INIS)

    Nickel-based superalloys such as NiCoCrAlY are widely used in high-temperature applications, such as gas turbine components in the energy and aerospace industries, due to their strength, high elastic modulus, and high-temperature oxidation resistance. However, the processing of these alloys is complex and costly, and the alloys are currently used as a bond coat in thermal barrier coatings. In this work, the effect of cold press and sintering processing parameters on the microstructure and mechanical properties of NiCoCrAlY alloy were studied using the powder metallurgy route as a new way to obtain NiCoCrAlYTa samples from a gas atomized prealloyed powder feedstock. High mechanical strength and adequate densification up to 98% were achieved. The most suitable compaction pressure and sintering temperature were determined for NiCoCrAlYTa alloy through microstructure characterization. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive spectroscopy microanalysis (EDS) were performed to confirm the expected γ-Ni matrix and β-NiAl phase distribution. Additionally, the results demonstrated the unexpected presence of carbides and Ni–Y-rich zones in the microstructure due to the powder metallurgy processing parameters used. Thus, microhardness, nanoindentation and uniaxial compression tests were conducted to correlate the microstructure of the alloy samples with their mechanical properties under the different studied conditions. The results show that the compaction pressure did not significantly affect the mechanical properties of the alloy samples. In this work, the compaction pressures of 400, 700 and 1000 MPa were used. The sintering temperature of 1200 °C for NiCoCrAlYTa alloy was preferred; above this temperature, the improvement in mechanical properties is not significant due to grain coarsening, whereas a lower temperature produces a decrease in mechanical properties due to high porosity and

  12. Carbide Dissolution/Carbon Loss as a Function of Spray Distance in Unshrouded/Shrouded Plasma Sprayed Cr3C2-NiCr Coatings

    Science.gov (United States)

    Matthews, S.

    2015-02-01

    Thermal spraying of Cr3C2-NiCr composites generates varying degrees of carbide dissolution into the Ni binder. During high-temperature exposure, the carbide dissolution zones precipitate high concentrations of small carbides which develop into finely structured networks. This raises the possibility of producing unique tailored carbide composite structures through the generation of controlled carbide dissolution and appropriate heat treatment. The first step in this process is to produce a supersaturated Ni-Cr-C solid solution from which the carbide phase could be precipitated. In a previous work, a broad range of plasma parameters were trialed to assess their effect on the degree of carbide dissolution at a fixed spray distance of 100 mm. The current two-part work builds on the most promising plasma parameters from those trials. In Part 1 of this two-part article series, the effect of spray distance on the extent of carbide dissolution and carbon loss during high energy plasma spraying was investigated. The effectiveness of solid shield and gas shrouding is contrasted, and the mechanisms by which they influence the degree of decarburization discussed.

  13. Optimization of Ni-Based WC/Co/Cr Composite Coatings Produced by Multilayer Laser Cladding

    Directory of Open Access Journals (Sweden)

    Andrea Angelastro

    2013-01-01

    Full Text Available As a surface coating technique, laser cladding (LC has been developed for improving wear, corrosion, and fatigue properties of mechanical components. The main advantage of this process is the capability of introducing hard particles such as SiC, TiC, and WC as reinforcements in the metallic matrix such as Ni-based alloy, Co-based alloy, and Fe-based alloy to form ceramic-metal composite coatings, which have very high hardness and good wear resistance. In this paper, Ni-based alloy (Colmonoy 227-F and Tungsten Carbides/Cobalt/Chromium (WC/Co/Cr composite coatings were fabricated by the multilayer laser cladding technique (MLC. An optimization procedure was implemented to obtain the combination of process parameters that minimizes the porosity and produces good adhesion to a stainless steel substrate. The optimization procedure was worked out with a mathematical model that was supported by an experimental analysis, which studied the shape of the clad track generated by melting coaxially fed powders with a laser. Microstructural and microhardness analysis completed the set of test performed on the coatings.

  14. A mechanism of swelling suppression in phosphorous-modified Fe-Ni-Cr alloys*1

    Science.gov (United States)

    Lee, E. H.; Mansur, L. K.

    1986-11-01

    Five simple alloys were ion irradiated at 948 K in an experiment designed to investigate the mechanism of swelling suppression associated wtih phosphorous additions. One of the alloys was the simple ternary Fe-15Ni-13Cr, another had 0.05% P added and the other three had further additions of the phosphide precipitate-forming elements Ti and/or Si. Ion irradiations were carried out with heavy ions only (Ni or Fe) or with heavy ions followed by dual heavy ions and helium. The ternary with and without P swelled readily early in dose with or without helium. The other three alloys only showed swelling in the presence of helium and exhibited a long delay in dose prior to the onset of swelling. These displayed fine distributions of Fe 2P type phosphide precipitates enhanced by irradiation. The phosphide particles gave rise to very high concentrations of stable helium filled cavities at the precipitate matrix interfaces. The results were analyzed in terms of the theory of cavity swelling. The accumulation of the critical number of gas atoms in an individual cavity is required in the theory for point defect driven swelling to begin. It is concluded that the primary mechanism leading to swelling suppression is therefore the dilution of injected helium over a very large number of cavities. It is suggested that this mechanism may offer a key for alloy design for swelling resistance in high helium environments.

  15. NI-Cr 合金中添加 Ni/C 制备自润滑金刚石工具%Manufacturing of self-lubricating diamond tools with Ni-Cr alloy adding with Ni/C

    Institute of Scientific and Technical Information of China (English)

    孟普; 甘瑞霞

    2015-01-01

    Ni-Cr alloy adding with Ni /C of 3%,5% was utilized to braze diamond grains in protective furnace with the temperature 1 050 ℃ and holding time 5 min,respectively.Diamond morphology and the brazed joint mi-crostructure were analyzed with the help of scanning electron microscope;the brazed joint hardness was measured by Vickers.The results show that Ni-Cr alloy adding with Ni /C has good wettability with diamond;it could a-chieve high strength bonding between diamond and brazing layer.Carbide crystallizes and nucleates on the surface of diamond has an orientation relationship with diamond surface.The Cr7 C3 morphology is hollow and clusters eu-tectic graphite forms in the brazing layer,which has a relationship with the adding Ni /C.There is small amount of Ni /C within brazing layer,the brazed joint hardness falls from 830 HV0.2 to 700 HV0.2,this is benefit to de-crease the thermal stress and improve the protrusion of diamond in the later grinding.%利用添加3%、5%的 Ni-Cr 合金在保护气氛炉中制备金刚石试样,钎焊温度为1050℃,保温5 min。采用扫描电镜分析钎焊金刚石形貌和钎缝的微观组织,维氏硬度计测量接头的硬度。结果表明:添加 Ni /C 的 Ni-Cr 合金对金刚石具有较好的润湿性,可以实现高强度连接,碳化物在金刚石表面形核和结晶长大,与金刚石表面的原子分布具有一定位向关系。钎缝中形成的空心 Cr7C3和簇状共晶石墨与添加的 Ni /C 有关,钎焊层中有少量 Ni /C剩余,硬度从830HV0.2降低到700HV0.2,这有利于降低钎焊热应力和金刚石后期的出露高度。

  16. Microstructure and flow behavior of Ni-Cr-Fe welds with Nb and Mo additions

    Energy Technology Data Exchange (ETDEWEB)

    Jeng, Sheng-Long, E-mail: sljeng@iner.gov.tw [Institute of Nuclear Energy Research, Nuclear Fuels and Materials Division, P O Box 3-14, Longtan, Taoyuan, 32546, Taiwan (China); Chang, Yun-Han, E-mail: yhchang@iner.gov.tw [Institute of Nuclear Energy Research, Nuclear Fuels and Materials Division, P O Box 3-14, Longtan, Taoyuan, 32546, Taiwan (China)

    2013-01-10

    This paper was intended to investigate the influence of niobium and molybdenum on the microstructure and flow behavior of Ni-Cr-Fe welds at room/elevated temperature. Microstructural examinations and mechanical tests were performed on the weld specimens of Alloy 52, Alloy 52M and two variants with higher contents of niobium and molybdenum. In Alloy 52 weld, without the additions of niobium and molybdenum, TiCs/TiNs were present in the matrix and Cr-carbides precipitated along the grain boundary. It was noted that niobium could strengthen the welds with the precipitation of small NbCs/(Nb,Ti)Cs, while molybdenum could not only precipitation-strengthen with small (Nb,Mo)/Cs but also solution-harden the welds. Both of niobium and molybdenum would increase the amount and size of Laves phases when their additions were higher. The average hardness, yield and tensile strength of the welds increased with the contents of niobium and molybdenum. Jerky flow was found on the stress-strain curves at 300 Degree-Sign C, except for the Alloy 52M weld. Ductile dimples were the dominant fracture feature of the welds with lower niobium contents. With the Nb/Mo additions, precipitation and the solution strengthening resulted in a decrease of slip lines in the matrix.

  17. Microstructure and AMR Properties of Permalloy Films Sputtered on (Ni0.81Fe0.19)0.66Cr0.34 Buffer

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-fei; PENG Zi-long; LIAO Hong-wei; LI Zuo-yi

    2004-01-01

    ( Ni0.81 Fe0.19 )0.66Cr0.34 has a high resistivity and a crystal structure close to that of Ni0.81Fe0.19. The electrical and X-ray diffraction measurements prove that a thin NiFeCr seed layer induces a well(111)-oriented Ni0.81Fe0.19 film. Post-annealing treatment improves the magnetic properties of (Ni0.81 Fe0.19)0.66Cr0.34(45A)/Ni0.81Fe0.19(150A)/Ta(55A)thin film prepared under a deposition field , whereas the inter-diffu-sion of NiFe/ Ta deteriorates the magnetoresistance properties of the film.

  18. Effects of composition and helium injection on dislocation loop development in pure FeNiCr alloys under Ni ion irradiation

    Science.gov (United States)

    Kimoto, Takayoshi

    1993-08-01

    Pure Fe35Ni7Cr, Fe45Ni7Cr, Fe40Ni13Cr and Fe45Ni15Cr alloys were irradiated by 4MeV Ni 2+ ions at 948 K to doses of about 0.05, 0.3 and 1.0 dpa without helium injection or with simultaneous helium injection. With increasing Ni content and decreasing Cr content, the diameter of radiation-induced dislocation loops increased, and the dose at which the dislocation loops disappeared to develop into dislocation networks decreased. The diameter of dislocation loops induced by Ni 2+ ions irradiation with simultaneous helium injection was larger than that without helium injection for the Fe35Ni7Cr and Fe45Ni7Cr alloys.

  19. Complicaciones relacionadas con catéteres venosos centrales en niños críticamente enfermos

    OpenAIRE

    Miguelena, Dayra; PARDO, ROSALBA; Moron Duarte, Lina Sofía

    2014-01-01

    Objetivo La colocación de catéteres centrales (CVC) es una práctica común para el manejo de pacientes críticos. El propósito de este estudio fue identificar las principales complicaciones y conocer la incidencia de las complicaciones mecánicas e infecciosas relacionadas con la colocación de catéteres venosos centrales en niños críticamente enfermos.Materiales y Métodos Estudio descriptivo realizado entre octubre 2011 a marzo 2012 en todos los niños críticamente enfermos a quienes se les coloc...

  20. EIS Evaluation of Fe, Cr, and Ni in NaVO3 at 700°C

    Directory of Open Access Journals (Sweden)

    O. Sotelo-Mazón

    2014-01-01

    Full Text Available Due to the depletion of high-grade fuels and for economic reasons, use of residual fuel oil in energy generation systems is a common practice. Residual fuel oil contains sodium, vanadium, and sulphur as impurities, as well as NaCl contamination. Metallic dissolution caused by molten vanadates has been classically considered the main corrosion process involved in the degradation of alloys exposed to the combustion products of heavy fuel oils. Iron and nickel base alloys are the commercial alloys commonly used for the high temperature applications, for example, manufacture of components used in aggressive environments of gas turbines, steam boilers, and so forth. Therefore, because the main constituents of these materials are Fe, Cr, and Ni, where Cr is the element responsible for providing the corrosion resistance, in this study the electrochemical performance of Fe, Cr, and Ni in NaVO3 at 700°C in static air for 100 hours was evaluated.

  1. Structure and Properties of the Hardmetal Coatings Cr3C2-25NiCr Formed by a Multi-chamber Detonation Sprayer

    Directory of Open Access Journals (Sweden)

    Kovaleva M.G.

    2015-01-01

    Full Text Available The hardmetal Cr3C2-25NiCr (180-220 μm thick coatings have been produced on a steel substrate by a multi-chamber detonation sprayer (MCDS. The characteristic feature of MCDS is that the powder is accelerated by using combustion products that are formed in MCDS chambers and are converged before entering the nozzle, where they interact with the two-phase gas-powder cloud. The microstructures and properties of the hardmetal coatings were examined with the use of optical microscopy, scanning electron microscopy, X-ray phase analysis, and a Vickers hardness tester with a 300 g test load. Wear tests were carried out using a computer controlled pin-on-disc type tribometer. It was established that MCDS has provided the conditions for formation of a dense hardmetal Cr3C2-25NiCr (180-220 μm thick coatings with a porosity of less than 0.02%, microhardness 540±210 HV0.3 and a specific wear rate of 9.08∙10-5 mm3(m∙N-1.

  2. X6CrNiTi18-10和X6Cr13的焊接工艺研究

    Institute of Scientific and Technical Information of China (English)

    魏晓侠

    2014-01-01

    Due to the need for gas turbine manufacturing, the welding of two kinds of different material X6CrNiTi18-10 and X6Cr13 is carried out, the research of weld test is conducted. This paper is aimed at the dissimilar steel welding, analyzes the welding characteristics of the dissimilar steel, choose the appropriate welding method and weld materials. And by the ifnal experiment, the results verify the feasibility of the welding process scheme. It can be used to guide welding production of practical products.%为满足燃机产品的使用要求,很多结构的连接处出现了X6CrNiTi18-10和X6Cr13异种钢焊接接头。针对这两种异种钢材料的焊接工艺进行了试验研究,分析母材特性,选择合适的焊接方法以及焊接材料,并通过试验结果验证焊接工艺方案的可行性,用于指导实际产品的焊接生产。

  3. Levels Of Heavy Metals (Hg, Pb, Cd, And Cr In Tissues Of Trachurus Trachurus

    Directory of Open Access Journals (Sweden)

    Enkeleda Ozuni

    2012-09-01

    Full Text Available The study was carried out to monitor the concentration level of mercury, lead, cadmium and chrome in different tissues of Trachurus trachurus (Horse mackerel. The concentration level of heavy metals was measured by using atomic absorption spectrophotometer (AAS. Concentrations of heavy metals in muscle tissue and liver of this animal ranged as follows: Hg 0.032-0.106; Cd nd-0.067 mg/kg wet weight; Pb and Cr resulted always below the detection level (nd in all tissue samples. According to the results the concentration levels of heavy metals measured in the muscle tissue was lower than the maximum permitted level for human consumption set by EC and Albanian regulation. The results obtained from the study indicate that heavy metal levels are in acceptable limits, so this product can be used as food for human consumption.

  4. Uticaj brzine depozicije praha na mehaničke karakteristike i strukturu APS-NiCr/Al prevlake / Effect of the powder deposition rate on the mechanical properties and the structure of the APS-NiCr/Al coating

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2010-10-01

    Full Text Available U radu su prikazani rezultati ispitivanja atmosferskih plazma-sprej prevlaka APS-NiCr/Al. Kompozitni prah NiCr/Al koji se sastoji od NiCr čestica obloženih finim česticama Al u procesu depozicije omogućuje egzotermnu reakciju. Reakcija ovih metala dovodi do formiranja samovezujućih NiCrAl prevlaka koje poseduju jedinstvene kombinacije osobina. Radi dobijanja najboljih strukturnih i mehaničkih karakteristika izvršena je optimizacija parametara depozicije. U ovom istraživanju urađene su tri grupe uzoraka prevlake NiCrAl sa različitim brzinama depozicije praha da bi se dobili depoziti velike čvrstoće i žilavosti. Kod prve grupe uzoraka brzina depozicije praha bila je 50 g/min, kod druge 40 g/min, a kod treće 30 g/min. Procena osobina depozita rađena je ispitivanjem mikrotvrdoće metodom HV0.3 i čvrstoće spoja ispitivanjem na zatezanje. Metalografska procena strukture rađena je tehnikom svetlosne mikroskopije. Verifikovane prevlake primenjene su za zaštitu i revitalizaciju delova turbomlaznih motora izloženih oksidaciji na povišenim temperaturama. / The paper presents the results of the examination of atmospheric plasma spraying of APS-NiCr/Al coatings. Composite NiCr/Al powders, composed of NiCr particles coated with fine Al particles, enable an exothermic reaction during the deposition process. The exothermic reaction of these metals results in the formation of selfbonding NiCrAl coatings with a unique combination of properties. For the purpose of obtaining excellent structural and mechanical properties, the deposition parameters were optimized. In this study, three groups of NiCrAl coating samples with different powder deposition rate were made to get deposits of greater strength and toughness. In the first group of samples, the deposition rate was 50g/min, in the second group the powder deposition rate was 40 g/ min. while in the third group it was 30 g/min. The assessment of the properties of deposits was made by the HV0

  5. Ni-Cr-Al-Y涂层真空热处理过程中元素的行为%EVOLUTION OF ELEMENT DISTRIBUTION IN Ni-Cr-Al-Y COATING BEFORE AND AFTER VACUUM HEAT TREATMENT

    Institute of Scientific and Technical Information of China (English)

    王冰; 黄荣芳; 宫骏; 王启民; 梁越; 孙超; 闻立时; 韩雅芳

    2000-01-01

    采用电弧离子镀技术在铸造镍基合金K17和Ni3Al基合金IC-6上沉积Ni-Cr-Al-Y涂层.结果表明,在沉积过程中由于电弧离子镀的"溅射"和"反溅射"效应以及基体和涂层发生互扩散的共同作用下,沉积的Ni-Cr-Al-Y涂层在靠近基体区含有少量基体元素,如Co,Ti和Mo等.K17合金中的Al元素可抑制Cr由涂层向基体扩散.IC-6合金中由于还含有Mo元素,使这种抑制作用进一步增强在1050℃真空热处理时,各元素互扩散能力增强,大量的Cr克服Al和Mo元素的束缚向基体扩散,最终使两种合金上沉积的Ni-Cr-Al-Y涂层中的元素均匀分布.

  6. Gas Detonation Spray Cr3C2-NiCr Coating and Its Application in Conticaster Rolls%爆炸喷涂Cr3C2-NiCr涂层及其在连铸辊上的应用

    Institute of Scientific and Technical Information of China (English)

    王俊; 张立; 李克; 孙宝德; 周尧和

    2000-01-01

    基于高温、高湿、磨损等综合作用将导致连铸辊的失效,采用气体爆炸喷涂工艺制备了以NiCr为底层、Cr3C2-NiCr为表层,厚约0.3 mm的涂层.该涂层致密度高,不仅与基体材料有着高的结合强度,同时具有很好的抗热冲击性、高温抗氧化性与耐磨性.该工艺加工的连铸辊在宝钢炼钢厂连铸机上使用7 000炉后,涂层表面未发生明显变化,而未加工连铸辊在3 740炉后,表面均已出现明显裂纹,并有部分辊子因裂纹超过检修标准而不得不下线修复.研究结果表明,该涂层是延长连铸辊使用寿命的有效措施.

  7. Bioaccumulation of Pb, Cd, Cu, and Cr by Porphyridium cruentum (S.F. Gray Nägeli

    Directory of Open Access Journals (Sweden)

    Tri Retnaningsih Soeprobowati

    2013-06-01

    Full Text Available The red microalgae Porphyridium cruentum (S.F. Gray Nägeli usually was used as feeds, a pigment for food and cosmetic, and antiviral activity that might be became industrial interest. Similar to another microalgae, P. cruentum has an ability to remediate heavy metals pollution, however research on it still limited. This research was conducted in order to find out the the accumulation of Pb, Cd, Cr, and Cu on the P. cruentum. A laboratory experiment were developed with different concentrations. Based on this research, P. cruentum with the treatment of 1 mg/L had reduced higher Cu, Pb, Cd, and Cr concentrations rather than 3 and 5 mg/L concentrations, respectively. This was also similar to the BCF, that in day 8 in order of Cu > Cr > Cd > Pb, respectively; however, in day 15 was Cu > Pb > Cd > Cr. The length of treatment influenced BCF value. P. cruentum was good for bioremediation of heavy metal pollution, with the advantage of the short of accumulation time.

  8. Dynamic off-centering of Cr$^{3+}$ ions and short-range magneto-electric clusters in in CdCr$_2$S$_4$

    CERN Document Server

    Oliveira, Gonçalo Nuno; Lopes, Armandina Lima; Amaral, João Sequeira; dos Santos, António; Ren, Yan; Mendonca, Tania Manuela; Sousa, Célia Tavares; Amaral, Vitor Sequeira; Correia, João Guilherme; Araújo, João Pedro

    2012-01-01

    The cubic spinel CdCr$_2$S$_4$ gained recently a vivid interest, given the relevance of relaxor-like dielectric behavior in its paramagnetic phase. By a singular combination of local probe techniques namely Pair Distribution Function and Perturbed Angular Correlation we firmly establish that the Cr ion plays the central key role on this exotic phenomenon, namely through a dynamic off-centering displacement of its coordination sphere. We further show that this off centering of the magnetic Cr-ion gives rise to a peculiar entanglement between the polar and magnetic degrees of freedom, stabilizing, in the paramagnetic phase, short range magnetic clusters, clearly seen in ultra-low field susceptibility measurements. Moreover, the Landau theory is here used to demonstrate that a linear coupling between the magnetic and polar order parameters is sufficient to justify the appearance of magnetic cluster in paramagnetic phase of this compound. These results open insights on the hotly debated magnetic and polar interac...

  9. First-Principles Study on the Half-Metallicity of Half-Heusler Alloys: XYZ (X=Mn, Ni; Y=Cr, Mn; Z=As, Sb)

    Institute of Scientific and Technical Information of China (English)

    LI Guan-Nan; JIN Ying-Jiu

    2009-01-01

    The electronic structures, magnetism, and half-metallicity of half-Heusler alloys XYZ (X=Mn, Ni; Y=Cr, Mn;Z=As, Sb) are investigated by means of the full-potential linearized augmented plane wave method within the generalized gradient approximation.We consider three types of atomic ordering (i.e.,α,β, and γ phases for all of the alloys) and find that the a phase is energetically the most stable.From the calculated density of states and the total magnetic moments, we find that NiMnZ (Z=As, Sb) and NiCrAs are half-metallic ferromagnets, MnCrAs is a half-metallic antiferromagnet, and NiCrSb (MnCrSb) is almost a half-metallic ferromagnet (antiferromagnet).

  10. Microstructural features and properties of plasma sprayed YPSZ/NiCrAlY thermal barrier coating (TBC)

    Institute of Scientific and Technical Information of China (English)

    孙大谦; 王文权; 宣兆志; 宫文彪

    2004-01-01

    The plasma sprayed thermal barrier coating (TBC) consists of NiCrAlY bond coating and yttria partially stabilized zirconia (YPSZ) top coating. NiCrAlY coating mainly contains Ni solid solution with face centered cubic lattice, Al2O3 oxides and pores. The most obvious feature of YPSZ coating with tetragonal zirconia is a lot of vertical microcracks in this coating. The thermal insulation capability of the TBC increased with an increase in YPSZ coating thickness, the temperature drop across the TBC increasing from 60℃ to 92℃ with increasing YPSZ coating thickness with increasing YPSZ coating thickness and cracks initiated mainly in original vertical microcrack tips of the YPSZ coating and propagated not only along YPSZ coating / NiCrAlY coating interface but also through into two stages: transient oxidation stage with rapid oxidation rate and steady oxidation stage with slow oxidation. Their transition time was favorable to increase YPSZ coating toughness and to decrease the pores and oxides of the TBC system for improving thermal shock resistance and oxidation resistance of the TBC.

  11. Effect of Aluminium and Silicon on High Temperature Oxidation Resistance of Fe-Cr-Ni Heat Resistant Steel

    Institute of Scientific and Technical Information of China (English)

    WANG Haitao; ZHAO Qi; YU Huashun; ZHANG Zhenya; CUI Hongwei; MIN Guanghui

    2009-01-01

    Fe-Cr-Ni heat resistant steels with different contents of Al and Si were cast in intermediate frequency induction furnace with non-oxidation method. With oxidation weight gain method, the oxidation resistance of test alloys was examined at 1 200℃ for 500 h. The effects of Al and Si on oxidation resistance were studied through analyses of X-ray diffraction (XRD) and scanning electron microscope (SEM). It is shown that the composition of oxide scales is a decisive factor for the oxidation resistance of heat resistant steels. The compounded scale composed of Cr2O3, ar-Al2O3, SiO2 and Fe(Ni)Cr2O4, with flat and compact structure, fine and even grains, exhibits complete oxidation resistance at 1 200℃ Its oxidation weight gain rate is only 0.081 g/(m2·h). By the criterion of standard Gibbs formation free energy, a model of nucleation and growth of the compounded scale was established. The formation of the compounded scale was the result of the competition of being oxidated and reduction among Al, Si, and the matrix metal elements of Fe, Cr and Ni. The protection of the compounded scale was analyzed from the perspectives of electrical conductivity and strength properties.

  12. Corrosion Resistance of Dissimilar Steel Welding Joint of 2205 and 15MnNiCrMoV%2205与15MnNiCrMoV异质钢焊接接头的耐蚀性能

    Institute of Scientific and Technical Information of China (English)

    张敏; 张恩华; 孟强; 支金花; 张海存

    2012-01-01

    Using the method of steel component analysis and metallographic analysis, the corrosion products of welding joint of duplex stainless steel 2205 and low carbon alloy 15MnNiCrMoV immersed in HC1 and H2 SO4 solution (10%,mass fraction) at 35 ℃ were studied. The results show that the corrosion resistance of welding joint was poor in the HC1 solution, and corrosion resistance of the heat affected zone was poorer than that of weld area. The corrosion of welding joint of 15MnNiCrMoV side was more serious in the H2SO4 solution, especially with its heat affected zone. However, the welding joint compound did not have any corrosion in the side of duplex stainless steel 2205, due to the form ation of passivation films, such as Cr2 O3, FeO and Cr-O on the surface of duplex stainless steel 2205, which can prevent corrosion.%双相不锈钢2205与低碳合金调质高强钢15MnNiCrMoV复合板焊接接头,35℃下,在质量分数为10%的HCl和H2sO4腐蚀溶液中,对其腐蚀产物进行了分析,结果表明,复合板焊接接头在HCl溶液中的耐蚀性较差,且热影响区的腐蚀程度均比焊缝处的严重;在H2S04溶液中,焊接接头15MnNiCrMoV侧的腐蚀比在相同条件下的HCl中严重,尤其是热影响区对H2SO4的耐蚀性较差,而焊接接头双相不锈钢2205侧在H2SO4溶液中未发生腐蚀。其原因主要是在双相不锈钢表面形成了钝化型的Cr2O3、FeO、Cr-O等氧化物膜层。

  13. Study of magnetism in Ni-Cr hardface alloy deposit on 316LN stainless steel using magnetic force microscopy

    Science.gov (United States)

    Kishore, G. V. K.; Kumar, Anish; Chakraborty, Gopa; Albert, S. K.; Rao, B. Purna Chandra; Bhaduri, A. K.; Jayakumar, T.

    2015-07-01

    Nickel base Ni-Cr alloy variants are extensively used for hardfacing of austenitic stainless steel components in sodium cooled fast reactors (SFRs) to avoid self-welding and galling. Considerable difference in the compositions and melting points of the substrate and the Ni-Cr alloy results in significant dilution of the hardface deposit from the substrate. Even though, both the deposit and the substrate are non-magnetic, the diluted region exhibits ferromagnetic behavior. The present paper reports a systematic study carried out on the variations in microstructures and magnetic behavior of American Welding Society (AWS) Ni Cr-C deposited layers on 316 LN austenitic stainless steels, using atomic force microscopy (AFM) and magnetic force microscopy (MFM). The phase variations of the oscillations of a Co-Cr alloy coated magnetic field sensitive cantilever is used to quantitatively study the magnetic strength of the evolved microstructure in the diluted region as a function of the distance from the deposit/substrate interface, with the spatial resolution of about 100 nm. The acquired AFM/MFM images and the magnetic property profiles have been correlated with the variations in the chemical compositions in the diluted layers obtained by the energy dispersive spectroscopy (EDS). The study indicates that both the volume fraction of the ferromagnetic phase and its ferromagnetic strength decrease with increasing distance from the deposit/substrate interface. A distinct difference is observed in the ferromagnetic strength in the first few layers and the ferromagnetism is observed only near to the precipitates in the fifth layer. The study provides a better insight of the evolution of ferromagnetism in the diluted layers of Ni-Cr alloy deposits on stainless steel.

  14. La argumentación como constituyente del pensamiento crítico en niños

    Directory of Open Access Journals (Sweden)

    Oscar Eugenio Tamayo Alzate

    2012-01-01

    Full Text Available El informe de investigación que presentamos a continuación hace parte de un proyecto de investigación que estudia el pensamiento crítico en niños desde tres categorías: solución de problemas, argumentación y metacognición. En estas páginas solo nos referiremos a los procesos argumentativos realizados por niños de 4º y 5º grado de educación básica primaria, para lo cual seguimos un diseño metodológico mixto. Para la intervención didáctica en función de desarrollar pensamiento crítico en los estudiantes se diseñaron diez actividades, las cuales fueron aplicadas a 2.200 niños de 56 instituciones educativas públicas. Los análisis cualitativos y cuantitativos fueron realizados con 220 niños. Los principales resultados describen las estructuras argumentativas empleadas por los niños durante las diferentes actividades de aula presentadas. Concluimos con algunas recomendaciones desde la didáctica de las ciencias orientadas a cualificar los procesos y productos argumentativos.

  15. Oxidation behavior of Ni(Co)CrAlYHf(Si) coatings on DS superalloy at 1 150 ℃

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhao-hui; TAN Yong-ning; ZHAO Xi-hong; LI Jian-ping; ZHANG Qiang

    2006-01-01

    Two Ni(Co)CrAlY coatings were deposited by EB-PVD method on a DS superalloy of Ni-Al-Cr-Co-W-Mo-Ta-Hf system. SEM, XEDS and XRD were used to study the oxidation behavior of the coatings. The two coatings show a good protection for the DS superalloy. The results of the isothermal oxidation test at 1 150 ℃ for 100 h show that the oxidation tendency obeys the parabolic law, and the oxidation rate constant Kp of the coated specimens decreases to about 1/3 of that for the bare superalloy. After oxidation, a continuous alumina-based scale is formed at the surfaces of the coated samples. Y2O3, NiO and SiO2 are also detectable in the oxide scale. A large number of Al in the coating is consumed due to high-temperature diffusion and oxidation reactions, and the NiAl phases in the coating are almost completely transformed to Ni3Al phases. For the Hf-bearing coating, some HfO2 particles exist at the interface between the coating and the substrate. Although internal oxidation occurs, the coating still shows a good adhesion with the superalloy substrate even after oxidation for 100 h. For the bare DS superalloy, after 100 h oxidation at 1 150 ℃, only discontinuous alumina-based oxide particles exist on the surface. Oxide spallation occurs for the bare alloy.

  16. Effect of Cerium on Microstructure and Electrochemical Performance of Ti-V-Cr-Ni Electrode Alloy

    Institute of Scientific and Technical Information of China (English)

    Qiao Yuqing; Zhao Minshou; Zhu Xinjian; Cao Guangyi

    2007-01-01

    Effect of cerium on the microstructure and electrochemical performance of the Ti0.25V0.35-xCexCr0.1Ni0.3 (x=0, 0.005) electrode alloy was investigated by X-ray diffraction (XRD), field emission scanning electron microscopy/energy dispersive X-ray spectrometry (FESEM-EDS), and electrochemical impedance spectroscopy (EIS) measurements. On the basis of XRD and FESEM-EDS analysis, the alloy was mainly composed of V-based solid solution with body-centered-cubic structure and TiNi-based secondary phase. Ce did not exist in two phases, instead, it existed as Ce-rich small white particles, with irregular edges, distributed near the grain boundaries of the V-based solid solution phase. Discharge capacity, cycle stability, and high-rate discharge ability of the alloy electrode were effectively improved with the addition of Ce at 293 K. It was very surprising that the charge retention was abnormal with larger discharge capacity after standing at the open circuit for 24 h. EIS indicated that addition of Ce improved the dynamic performance, which caused the charge transfer resistance (RT) to decrease and exchange current density (I0) to increase markedly. The exchange current density of the electrochemical reaction on the alloy surface with Ce addition was about 2.07 and 3.10 times larger than that of the alloy without Ce at 303 and 343 K, respectively. The diffusion coefficient of hydrogen (D) in the bulk alloy electrode decreased with addition of Ce, but it did not decrease so much, and the apparent activation energy (△rH) was far higher than that of the AB5 type alloy.

  17. 回火温度对ZG35 Cr2 NiMoVTi钢组织性能的影响%Efefcts of tempering temperature on microstruct ure and properties of ZG35Cr2NiMoVTi steel

    Institute of Scientific and Technical Information of China (English)

    赵雪阳; 刘英; 李雪; 郭红; 刘亦文; 李卫

    2014-01-01

    Effects of tempering temperature on microstructure , hardness , impact toughness and impact-abrasion resistance of ZG35Cr2NiMoVTi steel were investigated .The results show that the quenched microstructure of ZG 35Cr2NiMoVTi is lath-shaped martensite and retained austenite .When tempering temperature elevated , the microstructure of the steel turns to tempered martensite , tempered bainite and troostite, tempered sorbite and tempered pearlite .With tempering temperature increasing , the hardness of ZG35Cr2NiMoVTi steel decreases , and the impact absorbing energy with V-notch increases at beginning , but decreases obviously when the tempering temperature reaches 400℃, and then increases with temperature increasing again .The maximum impact absorbed energy is 45 J when tempered at 600℃. The impact-abrasive wear resistance of ZG35Cr2NiMoVTi steel has the downward trend with tempering temperature increasing .The impact-abrasive wear resistance of the steel is better when tempered at 200℃and the impact-abrasive wear mechanism is mainly fatigue peeling wear and micro-cutting.The lowest impact-abrasive wear resistance is observed when tempered at 600 ℃ and the corresponding impact-abrasive wear mechanism is mainly push ploughing plastic deformation wear and micro -cutting.%研究了回火温度对 ZG35Cr2NiMoVTi 钢显微组织、硬度、冲击韧性及抗冲击磨料磨损性的影响。结果表明, ZG35Cr2NiMoVTi钢淬火后组织为板条状马氏体和少量残留奥氏体;提高回火温度,可依次得到回火马氏体、回火贝氏体与屈氏体、回火索氏体、回火珠光体;随回火温度提高,ZG35Cr2NiMoVTi钢硬度下降,V型缺口冲击吸收能量先增加,但在400℃时明显下降,随后又随回火温度提高而显著增加,600℃回火时,冲击吸收能量最大,为45 J;随回火温度升高,ZG35Cr2NiMoVTi钢耐磨性逐渐下降,200℃时耐磨性较好,主要磨损机制为疲劳剥

  18. Radiation processes in CdIn2S4 and CdIn2(1-x)Cr2xS4 monocrystals

    International Nuclear Information System (INIS)

    Results of studying luminescence of CdIn2S4 monocrystals, specially unalloyed and alloyed with chromium, are presented. Elementary components, forming integral spectrum, are isolated, energies of their maxima are determined. Nature of radiative recombination centers is ascertained, energy diagram of local levels is suggested. Criteria, permitting to estimate the degree of position disorder in cation sublattice, connected with partial inversion of spinel structure of the investigated crystals are found. Features of experimental methods of studying intracentral radiation of CdIn2S4: Cr monocrystals are considered. 83 refs.; 25 figs.; 1 tab

  19. Ni-Cr-B-Si+Cu-P-Sn复合钎料真空钎焊金刚石%Vacuum brazing diamond with Ni-Cr-B-Si+Cu-P-Sn composite filler metal

    Institute of Scientific and Technical Information of China (English)

    卢金斌; 贺亚勋; 张旺玺; 刘磊; 李华

    2016-01-01

    采用在镍基钎料中分别添加3%、5%和7%(质量分数)Cu-P-Sn组成新型复合钎料,并进行金刚石磨粒的钎焊实验,利用SEM、EDS和XRD对金刚石焊后的界面碳化物形貌及钎料组织进行测试分析。结果表明:添加5%Cu-P-Sn的复合钎料进行金刚石钎焊时,钎焊温度有所下降,金刚石表面碳化物较规整,并且数量有所下降,降低金刚石的热损伤。新型钎料中形成树枝晶α-Ni基固溶体和枝晶间Ni 31 Si 12、Cr 7 C 3等化合物的组织,不同含量Cu-P-Sn与Ni-Cr-B-Si合金可以较大程度互溶,可以实现钎料性能的调控,降低金刚石的热损伤。%A series of new composite brazing fillers metal were got by adding 3%, 5% or 7% (mass fraction) Cu-P-Sn in the primary brazing filler metal Ni-Cr-B-Si, respectively, then, they were used to braze diamond particles. The interface morphology of diamond carbide and the microstructure of brazing filler metal were tested by SEM, EDS and XRD. The results show that, when the composite brazing filler metal containing 5% Cu-P-Sn alloy, the carbide on the surface of the diamond is more regular and less with brazing temperature decreases, which decreases the thermal damage to the diamond. In the brazing filler alloy, the microstructures, such as dentrite included solid solution of Ni with some carbides like Ni31Si12 and Cr7C3, are formed. As the added component, Cu-P-Sn at different proportions can be dissolved into the primary brazing filler Ni-Cr-B-Si in large degree, which can adjust the properties of the filler and reduce the heat damage to the diamond.

  20. Tensile Properties and Microstructure of DS NiAl-28Cr-5.8Mo-0.2Hf Alloy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A multiphase alloy NiAl-28Cr-5.8Mo-0.2Hf was directionally solidified in Ar atmosphere in an Al2O3-SiO2 mold by standard Bridgman method. The fracture toughness and tensile properties at 980℃ as well as tensile creep at 1050℃were studied. It was found that the strength of the present alloy is higher than that of many NiAl-based alloy and the stress exponent n for creep is about 6.69. Then the possible strengthening mechanism and creep mechanism are also discussed.