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Incorporating expensive alloying elements into bulk steel for corrosion protection is undesirable, considering that only the surfaces are exposed to aggressive environments. Therefore, this work focused on developing and optimizing a new surface functioning technology through in situ observation of thermal interactions between the metallic powders at elevated temperatures. The study revealed that the Cu-Ni powder mixture, with 12.5 wt% Ni, began to melt at 1099.5 °C and was fully melted at 1175 °C, significantly different from the Cu-Ni solid solution and bulk Cu or Ni. As a result of high-temperature reactions, copper penetration of up to 35 µm for pure copper and 55 µm for copper-chromium composite coatings occurred due to liquid metal corrosion. In contrast, the copper-nickel composite coating exhibited a cupronickel solution microstructure with FeNi dendrites and a nickel-rich transition layer. This cupronickel coating, with a chemical composition of 89.3 wt% Cu, 6.2 wt% Ni, and 4.5 wt% Fe, demonstrated uniform thickness, superior surface morphology, and continuous coverage on the steel substrate. Furthermore, the Ni-rich transition layer played a vital role in preventing copper penetration along the grain boundary of the steel matrix while forming a chemical binding between the coating and the substrate. The practicality of the coating was further confirmed through the hot-rolling procedure and subsequent electrochemical corrosion tests, which resulted in a 44% improvement in corrosion resistance. [ABSTRACT FROM AUTHOR]

This paper identifies the materials used to make a brocade belt belonging to the Qajar courtiers in Iran. This belt consists of two fabric types: red support and golden brocade. Accordingly, this paper examined the skin and tannin type, fiber types, dyeing agents, mordant, and metal wrapping of brocade yarns and metal buckle. Technical imaging, ESI–MS, FORS, FTIR and SEM–EDS were used to identify the materials. Multi-band imaging methods included Vis, UVL, IRR, and UVR, in which UVFC and IRFC images were obtained after processing. The results showed that cotton yarn was used in both fabrics. The red fabric yarns were dyed using cochineal and alum mordant. Also, the yellow brocade yarns were dyed using catechins-rich plants, and in this dyeing process, polyphenols and alum have been as mordant. Madder-dyed yarns are also found in parts of the belt. Examination of the metal wrapping of brocade yarns suggests using strips of copper-nickel alloy with a thin layer of gold-silver alloy. This secondary coating protects the copper-nickel strips and increases their golden luster. The leather analysis of the leather parts also indicated the using cattle/calfskin tanned with gallotannins. Belt buckle analysis also shows the use of brass alloy with a high percentage of zinc, leading to a golden sheen and the buckle desired strength. The results show the use of low-cost materials in the manufacture of clothing for the lower levels of the Qajar court. [ABSTRACT FROM AUTHOR]

The influence of sulfur on the hot compression properties of C71500 cupronickel alloy and the mechanism of thermo mechanical effect are studied for the first time. The composition of sulfide inclusions and its damage mechanism to properties were also studied. The effect of sulfur content on the dynamic recrystallization activation energy and the properties of the alloy was deduced and explained systematically. The relationship between the dynamic recrystallization activation energy and sulfur content was obtained, and a energy dissipation model was established based on the dynamic material model. The Prasad's instability criterion was used to predict the unstable region in the processing chart. The effect of sulfur on the processing parameters selection was compared under different strain conditions, which could provide the ideal processing technology for the thermal deformation of C71500 alloy with various sulfur content. [ABSTRACT FROM AUTHOR]

Constitutive analysis for elevated temperature flow behavior of BFe10-1-2 alloy was carried out by using experimental stress–strain data from isothermal hot compression tests on a Gleeble-3800 thermo-mechanical simulator, in a wide of temperature range of 1,023–1,273 K, and strain rate range of 0.001–10 s−1. A constitutive equation based on double multiple nonlinear regression (DMNR) was proposed considering the independent effects of strain, strain rate, temperature and their interrelation. The predicted flow stress data obtained from the developed equation based on DMNR was compared with the experimental data. Correlation coefficient (R), average absolute relative error (AARE) and relative errors were introduced to verify the validity of the developed constitutive equation. The results showed that the developed constitutive equation based on DMNR could predict flow stress of BFe10-1-2 alloy with good correlation and generalization. [ABSTRACT FROM AUTHOR]

• High-turbulent fluid pressures led to an erosion-wear corrosion failure mechanism and anti-abrasive coating can be used to modify the tube surface. • Wet H2S environment and iron oxidation led to tube pitting, leading to stress cracking that can be mitigated using claddings. • Humid environment with high sulfateate compounds and tensile residual stresses caused crack propagation. Excess residual stresses can be reduced by heat treatment. This study examined the premature failure of cupronickel (CuNi10Fe) tubes in a shell-and-tube heat exchanger after five months of service. An investigation to identify the root cause of the tube burst was carried out using macroscopic and microscopic inspection, chemical analysis, and mechanical analysis. The optical microscopy (OM) and scanning electron microscopy (SEM) evaluation revealed crack propagation characterized by pits and inclusions at the tube surface. This was due to the diffusion of hydrogen ions into the material from the hydrogen sulfide (H 2 S) rich geothermal environment. Furthermore, high tensile residual stresses of 172 MPa were recorded in the failed tube, leading to stress cracking in hydrogen-containing material. Additionally, the high sulfide content in corroded water and condensate samples suggests that the leading cause of tube rupture was through hydrogen embrittlement and sulfide stress cracking mechanism in the presence of hydrogen sulfide. Therefore, the use of laser cladding to protect tubes using functionally graded materials is recommended to mitigate degradation in aggressive environments, through careful material selection and additional water treatment to eliminate the contaminants. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • CuNi bimetal combined with CQDs was obtained by a hydrothermal method. • An enhancement of water splitting was achieved after modification with CQDs. • Non-semiconductor-driven photocatalysts were used in the photocatalyst field. • A possible mechanism is elucidated for photocatalytic activity improvement. Abstract In artificial photocatalysis, attention is focused mainly on semiconductor photocatalysts, due to their long research history and excellent photocatalytic performance. Here, we demonstrate that dendrite-like plasmonic CuNi bimetal, used as a nonsemiconductor photocatalyst, produces electrons for photocatalytic water splitting by the surface plasmon resonance (SPR) effect of the CuNi bimetal. Carbon quantum dots (CQDs), by virtue of their outstanding charge transfer properties, serve as a co-catalyst that can facilitate the transfer of the photoinduced charge. The photocatalytic water splitting rate of the CuNi bimetal was significantly improved after modification with CQDs, and the highest hydrogen evolution rate was 55.19 μmol g−1h−1, with an oxygen evolution rate of 27.51 μmol g−1h−1, when the content of CQDs in the photocatalyst was 3 wt%. X-ray diffraction and X-ray photoelectron spectroscopy characterization reveal that the structure and state of the element in the photocatalyst remain unchanged after four consecutive cycles of, cumulatively, 20 h. Our findings may help in the development of a non-semiconductor-driven photocatalytic system for application in the photocatalytic field. [ABSTRACT FROM AUTHOR]

This paper reports on the processing of Fe48Cr15Mo14Y2C15B6 amorphous alloy coatings on Cu-10%Ni (wt.%) alloy using spark plasma sintering. The amorphous alloy coatings were sintered at temperatures ranging from 575 to 675 °C at a pressure of 50 MPa. The development of microstructure, phases, and wear properties with sintering temperature of the coatings is investigated. The sintered coatings were found to be near fully dense with hardness close to that of the sintered bulk amorphous alloy. X-ray analysis indicated increasing degree of devitrification of the amorphous coatings with increasing sintering temperature. The wear behavior of the coatings is significantly influenced by the sintering temperature with volume wear rate first decreasing in the temperature range of 575-650 °C and then increasing above 650 °C. The variation in wear behavior is explained based on relative stability of the protective surface layer and embrittlement of the surface with the sintering temperature. [ABSTRACT FROM AUTHOR]

The deterioration of metals under the influence of corrosion is a costly problem faced by many industries. Therefore, particle-reinforced composite coatings are being developed in different technological fields with high demands for corrosion resistance. This work studies the effects of nanoplatelet reinforcement on the durability, corrosion resistance, and mechanical properties of copper-nickel coatings. A 90 : 10 Cu-Ni alloy was coelectrodeposited with nanoplatelets of montmorillonite (Mt) embedded into the metallic matrix from electrolytic baths containing 0.05, 0.10, and 0.15% Mt. X-ray diffraction of the coatings indicated no disruption of the crystal structure with addition of the nanoplatelets into the alloy. The mechanical properties of the coatings improved with a 17% increase in hardness and an 85% increase in shear adhesion strength with nanoplatelet incorporation. The measured polarization resistance increased from 11.77 kΩ·cm2 for pure Cu-Ni to 33.28 kΩ·cm2 for the Cu-Ni-0.15% Mt coating after soaking in a simulated seawater environment for 30 days. The incorporation of montmorillonite also stabilized the corrosion potential during the immersion study and increased resistance to corrosion. [ABSTRACT FROM AUTHOR]

The solid solution alloys containing short-range order (SRO) structure, such as CuNi alloys, are not well structurally described using conventional quasi-disordered models. Based on the first-principles calculations, the optimal cluster-plus-glue-atom (CPGA) models of six typical solid solution CuNi alloys were demonstrated. These CPGA models are better to be used to describe the microstructure of the six CuNi alloys at the atomic scale from the viewpoint of energy. Our further study shown that the stabilities of CPGA models are highly related to the symmetry of initial CPGA models and the aggregation degree of solute atoms in CPGA models. In the condition of low solute Ni concentration, the stability of CPGA model is mostly determined by the symmetry of initial CPGA model, the CPGA model with high symmetry is more stable. As the concentration of solute Ni increasing, the aggregation degree of solute Ni atoms in CPGA models plays more and more important role. The CPGA model with higher aggregation degree of solute Ni is more stable. The simple selection method of optimal CPGA models, therefore is proposed, and which can be extended to other bielement solid solution AB alloys with positive mixing enthalpy of A-B. Using the selected CPGA models, we found the third additive atoms having negative mixing enthalpy with solvent and solute atoms prefer to reside the central site of characteristic principal cluster (CPC) of CPGA, and thereby enhancing the stability of alloys. Our studies provide a distinctive perspective to select the optimal CPGA models of solid solution alloys containing SRO structure and design alloy using the optimal CPGA model. [ABSTRACT FROM AUTHOR]

Introduction: Contact with nickel-releasing coins as a cause of hand dermatitis has been debated. Aim: Studying a hand dermatitis risk from handling Kuwaiti cupronickel coins among nickel-allergic and nickel non-allergic subjects. Material and methods: One hundred hand dermatitis patients (group I: nickel-allergic) and 100 matched patients (group II: nickel non-allergic) were selected from over 500 hand dermatitis cases seen between September 2014 and September 2015. Nickel released from Kuwaiti cupronickel coins immersed in a standardized artificial sweat solution was measured at 1, 24, 48, 144 and 168 h at room temperature. Subjects in both groups were exposed to nickel releasing coins. The process was repeated after 3 months using nickel coated coins as controls. Results: Nickel released from 20, 50 and 100 fils Kuwaiti cupronickel coins at 1 week was 28.64, 32.76, 35.76 µg/cm²/week, respectively. Ninety-one patients (29 males, 62 females) in group I and 87 patients (38 males, 49 females) in group II completed the study. 47.3% in group I vs. 13.8% in group II developed dermatitis on exposure to nickel releasing coins. Nickel coated coins resulted in dermatitis in 8.8% of group I vs. 5.7% in group II. Conclusions: Nickel is released significantly from cupronickel Kuwaiti coins. Handling of coins caused dermatitis more often in patients with nickel-allergy compared to nickel non-allergic patients. [ABSTRACT FROM AUTHOR]

High temperature deformation behavior of BFe10-1-2 cupronickel alloy was investigated by means of isothermal compression tests in the temperature range of 1,023~1,273 K and strain rate range of 0.001~10 s-1. Based on orthogonal experiment and variance analysis, the significance of the effects of strain, strain rate and deformation temperature on the flow stress was evaluated. Thereafter, a constitutive equation was developed on the basis of the orthogonal analysis conclusions. Subsequently, standard statistical parameters were introduced to verify the validity of developed constitutive equation. The results indicated that the predicted flow stress values from the constitutive equation could track the experimental data of BFe10-1-2 cupronickel alloy under most deformation conditions. [ABSTRACT FROM AUTHOR]

With the rapid development of the shipping and the power industry, the demand for high-performance cupronickel alloy pipes is greatly increasing. The main processing methods of this alloy include semisolid ingot casting and deformation by hot extrusion. Many defects appear during the hot extrusion process for large diameter cupronickel alloy pipes, which results in considerable problems. Therefore, numerical simulation of hot extrusion for cupronickel alloy pipes before the practical production is of vital significance to properly determine the deformation parameters. In order to obtain the influence of processing parameters on the piercing extrusion process of large diameter cupronickel alloy pipe, metal flowing law under different deformation conditions was simulated and analyzed via employing a 3D FEM code. The results showed that piercing speed had no obvious influence on the cupronickel alloy billet. However, the friction had significant influence on the piercing process of cupronickel alloy billet: with the increase of friction coefficient, the temperature and the load increased. [ABSTRACT FROM AUTHOR]

Advances in flexible optoelectronic devices have led to increasing need for developing high performance, low cost, and flexible transparent conducting electrodes. Copper-based electrodes have been unattainable due to the relatively thermal instability and poor oxidation resistance. Herein, we present oxidation-resistive CuNi nanomesh electrodes that exhibit a low sheet resistance of ∼7.5 Ω/□ and a high optical transmittance of ∼81% at 550 nm. Further, high long-term stability against the effects of oxidation, heat, and chemicals is exhibited by the CuNi nanomesh, in comparison with the behavior of a pure Cu nanomesh sample. [ABSTRACT FROM AUTHOR]

The research of platinum metal recovery from compound solutions including process ones with high salt content in non-ferrous and other metals is given. Effective conditions for platinum metal sorption recovery from sulphate cupronickel solutions by nitrating and anodizing methods are stated. The level of platinum family recovery is 95-99%. [ABSTRACT FROM AUTHOR]

The paper describes an experimental study concerning the influence of major environmental parameters (temperature, chloride, carbon dioxide, and oxygen) on the corrosion behavior of 90/10 Cu–Ni alloys widely used for heat-transfer tubes. Electrochemical techniques have been used to investigate the corrosion behavior of 90/10 Cu–Ni alloys in aerated 3.5% NaCl solutions, at temperatures of 25, 50, and 80°C with and without the injection of carbon dioxide. The results have revealed increases in chloride corrosion rates of the 90/10 Cu–Ni alloy with temperature and decreases with CO2presence. Tests performed in aerated chloride–CO2solutions have shown higher corrosion rates relative to those conducted in deaerated chloride solutions saturated with CO2species. The surface morphology of polarized specimens in chloride solutions with and without CO2presence has shown a susceptibility to pitting attack. Pit characteristics have been found to be highly influenced by CO2presence. [ABSTRACT FROM AUTHOR]

After reviewing the initiation and growth models for discontinuous precipitation (DP) in metallic systems, this mode of transformation is examined in melt-spun supersaturated Cu-10 at.%Co. Detailed observations of the micro and nanostructures developed by DP and coarsening upon isothermal aging treatments at temperatures ranging from 450 to 650 °C are presented and discussed. Transmission electron microscopy has been extensively used in the characterization of precipitation phenomena. The analysis led us to propose a model for initiation and growth of DP and further coarsening in this alloy system. It is shown that, as precursor of DP, the onset of grain boundary migration is assisted by capillary forces and leaves a precipitate-free solute-depleted zone. Upon extended aging, discontinuous precipitation takes place as colonies of regularly spaced Co rod-like precipitates embedded in the depleted matrix. Discontinuous coarsening takes place generating arrays of coarser and wider-spaced precipitate colonies. Grain boundary curvature suggests that the transition from discontinuous precipitation to coarsening is related to the exhaustion of capillary, since in the latter, grain boundary migration occurs in the direction opposite to its center of curvature. [ABSTRACT FROM AUTHOR]

The low-temperature-fired NiCuZn ferrites with various borosilicate glasses were prepared by the conventional solid-state reaction method. Different weight percentages of glasses such as AlO-BO-SiO (ABS), NaO-AlO-BO-SiO (NABS), BiO-BO-BaO-SiO (BBBS) were added to low-temperature-fired NiCuZn ferrites. The effects of these glasses on sintering behavior, microstructures and magnetic properties of NiCuZn ferrites were also investigated. It is found that moderate amount of borosilicate glass addition can promote the densification and improve the magnetic properties of NiCuZn ferrites due to the formation of liquid phase, but too more liquid phase formation will deteriorate the magnetic properties. In addition, results also show that addition of BBBS glass can promote best densification of NiCuZn ferrites, but improve magnetic properties worse than addition of ABS or NABS glass. By contrast, the NiCuZn ferrite sample with 0.1 wt% ABS glass can obtain best magnetic properties: μ = 733.01 at 100 kHz, B = 162.39 mT, B = 86.59 mT and H = 35.7 A m. [ABSTRACT FROM AUTHOR]

This study on the population dynamics of fouling diatoms from a biofouling rich monsoon influenced tropical bay revealed that irrespective of the season and exposure period, the highest diatom abundance and species were encountered on non-toxic (fiberglass > glass) compared to toxic (copper–Cu and cupro-nickel–Cu-Ni) substrata. Though the diatom recruitment on toxic substrata is noticed within 24 h, the multiplication of the settled diatoms was not significant, even with an increase in the exposure period (days to weeks). The diatoms recorded on toxic substrata are the result of fresh recruitment. Results indicated that the potential of Cu and Cu–Ni panels to resist diatom fouling are the same. The dominance of raphid-pennate diatoms ( Navicula , Amphora , Nitzschia and Thalassionema ) throughout the year indicated them as ideal candidates for antifouling studies. The negligible contribution of araphid-pennate diatoms ( Licmophora and Grammatophora ) and the influence of tycho-pelagic/bloom forming diatoms ( Fragillariopsis and Skeletonema ) on fouling community are the other noteworthy observations. Concern with the adverse impact of Cu pollution on the ecosystem this study recommends the incorporation of Cu alloy (Cu–Ni) in the marine structures to combat biofouling as Cu–Ni has a slower leaching rate of the toxic product such as Cu 2 O. [ABSTRACT FROM AUTHOR]

Experiments were conducted on the condensing heat transfer of eleven horizontal tubes with refrigerant R134a at saturated temperature of 40 °C (1.01 MPa). The tube materials are titanium, cupronickel (B10 and B30), stainless steel and copper, among whom the former four materials are of low thermal conductivity. The enhanced tubes include integral-fin and three dimensional geometries. The results indicate that the heat transfer coefficients of the enhanced copper tube are about 1.6-2.1 times of low thermal conductivity tubes with the same enhanced geometries. Compared with plain tube the mean enhanced ratio of tubes made from titanium, B10, B30 and stainless steel are 8.48, 8.31, 8.22 and 7.52, respectively. The reason why low thermal conductivity affects the condensation heat transfer of enhanced structure is discussed in detail. [ABSTRACT FROM AUTHOR]

The aim of this work is to examine the possibility of CuNi protection in chloride media by self-assembled monolayers (SAMs) of stearic acid (SA). In order to obtain a compact, well ordered monolayer, that will provide long term protection, different SAM preparation procedures are studied. The influence of CuNi pretreatment, SA solution temperature and temperature of the drying period followed after the SA treatment on the protective properties of stearic acid self-assembled layer are examined by electrochemical methods and surface analysis techniques. The obtained results show that for complete self-assembled film formation it is necessary to have a drying period after exposing the sample to the stearic acid solution. Heating of the SA solution and drying period at higher temperatures result in layers with better stability in chloride media. The most compact surface layer, that provides long lasting and efficient protection to the underlying alloy, is obtained when prior to SA solution exposure an oxide layer on CuNi surface was formed at elevated temperatures. [ABSTRACT FROM AUTHOR]

Abstract: Pin-hole leakage was observed in a number of 90/10 cupronickel evaporator tubes of a chilling plant which was in service for about 6years. Chilled water is cooled from 12°C to 7°C which flows inside the evaporator tubes, while the OD side has LiBr environment. The failure investigation of the failed tubes revealed greenish/blackish uniform deposits together with some spots where localized thick deposits on the ID surfaces were present. Underdeposit corrosion beneath these thick deposits was the primary reason for failure of the tubes. Intergranular corrosion was also observed underneath the thick deposits. The ID surface of the failed tubes confirmed the presence of wide variety of deposits, e.g. carbonates, silicates, phosphates, and sulphur-bearing compounds. The stagnant conditions under the thick deposits alter the chemistry inside the crevices thus formed. The altered chemistry conditions caused rapid corrosion (and intergranular attack) on the cupronickel tubes. Remedial measures that may be undertaken to prevent future occurrence of the problem are addressed. [Copyright &y& Elsevier]

Abstract: The failure of 90/10 cupronickel heat exchanger tubes in hydrogen coolers were seen after few years in use. The tubes had river water flowing at a velocity of 2.5m/s. The shell side was exposed to hydrogen at a pressure of 3.5kg/cm2. The inlet and outlet temperature of the cooling water of the cooler are 37°C and 47°C, respectively. The failures were pin hole type with a thick layer of muck deposit on the inner side of the tube. The metallographic studies carried out for the tube showed a well annealed microstructure. The region near the pit showed attack along the grain boundaries with dislodging of the grains. The electron probe micro analysis (EPMA) studies revealed the denickelification near the pits. The energy dispersive spectroscopy (EDS) analysis of the pit showed the presence of copper chloride and also the variation in the copper and nickel concentration with respect to the unaffected regions of the tube. Microbial presence was detected in the water as well as the muck deposits in the tubes. The pin hole failure of the tube was a result of the combined action of the chloride as well as the deposits in the tube which gave a conducive environment for the microbial activity to flourish which has caused the propagation of the pit through intergranular corrosion. [Copyright &y& Elsevier]

Abstract: Failure analysis of cupronickel condenser tubes of a crude distillation unit of a petrochemical refinery has been conducted. Condenser tubes carrying sea water were found to undergo premature failure which was preceded by extensive overall thinning, formation of shallow channels, pits, etc., and greyish-black internal deposits in one of the units. In the other unit, the failure of tubes was noticed without any significant overall thinning and in the presence of adherent, hard and black-brown deposits. The studies indicated that the increased velocity of sea water as well as the deficiency of iron in the alloy had resulted in failure in one case whereas relatively low velocity of water associated with deposition of sludge and bio-fouling were the causes of failure in the other case. The failure of tubes could be controlled by maintaining the water velocity within a specified range, flushing the tubes with clean water, use of anti fouling paints, selecting a more appropriate composition of the cupronickel alloy, through control of sea water sulphur level, etc. [Copyright &y& Elsevier]

Abstract: On the basis of high temperature ductility tests in single-phase cupronickel CuNi25 sample has been found a relation between microstructure, grain size and effect of ductility minimum temperature (DMT). Metallographic tests confirmed literature studies that cracks nucleate at points of two or three grain joints and cross-cut of twined grain with border of the grains. The non-homogeneous character of chemical composition concentrating in areas of grain joints and cracks at high temperature has been investigated by linear and point Cu and Ni analysis (EDS). This analysis shows that local areas of non-equilibrium formation concentrate at this places. This fact can be accepted as one of the reasons of non-homogeneous deformation, cracking and its location at DMT. Experimental results were compared with two-dimensional finite element method (FEM) simulation results of proposed hypothesis of non-uniform deformation. [Copyright &y& Elsevier]