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Wet electrostatic precipitators (WESPs) are modern-era pollution control systems specifically designed to capture ultrafine particles as well as acid mist, highly resistive and sticky particles; however, this requires the use of expensive corrosion-resistant metal alloys. The work presented here is part of a continuing study at Ohio University aimed at reducing the cost of WESPs by using a novel combination of a polymer collector surfaces with a hybrid composite discharge electrode. In this study, a hybrid composite discharge electrode was tested, for the first time, inside a semipilot- scale experimental setup, with collection surfaces consists of a vertical array of strands. Particle laden gases were passed through this array of polymer ropes, which were kept wet by a small flow of water. The discharge electrodes were composite laminates of carbon fibers in a polymer matrix enclosing a metal mesh. The preliminary results showed that this new integrated system of composite discharge electrode and polymer collector surfaces can match or exceed the performance of a conventional metal alloy electrostatic precipitator (ESP) with metal discharge electrodes. There are additional advantages due to the system being compact, lightweight, and highly corrosion resistant. Implications: This study focused on integrating and assessing performance of a novel hybrid composite electrode (HCE) inside semi-pilot novel cross-flow electrostatic precipitator at conditions typically observed in coal-fired power plant exhausts. The results were collected for particulate collection efficiencies and were compared with a rigid metal electrode. The HCE outperformed metal electrode by showing higher particulate collection efficiency. This result showcases substantial potential for these two new technologies (HCE and cross-flow system) as a substitute for conventional metal based wet ESPs. [ABSTRACT FROM AUTHOR]

Plastic pipe reinforced by steel wires (PSP) is a new kind of composite pipe, which has the advantages of corrosion-resistant, light weight and low cost. Generally, the middle layer of PSP includes helically wound high-strength steel wires as enhanced body and high-density PE as a matrix. In the engineering practice, this kind of composite pipe endures combined bending and internal pressure. Thus, it is of great importance to investigate the burst pressure of PSP under this load condition. In this paper, a full-scale laboratorial test of PSP under combined bending and internal pressure was carried out. A finite-element model (FEM) was established to study the mechanical behaviour and failure mode. In addition, we deduced a simple but effective formula for calculating the burst pressure of PSP under combined bending and internal pressure. The results obtained from the three methods show a good agreement. [ABSTRACT FROM AUTHOR]

To understand the corrosion characteristics of W90 tungsten alloy and compare them with those of conventional hot-worked steel (SKD61), immersion tests were carried out in molten aluminium alloy (ADC12). Severe corrosion occurred in SKD61, whereas the corrosion resistance of W90 was about 40 times greater, with little occurring even after 300 h immersion. However, significant microstructural changes occurred in W90 resulting from penetration of aluminium and silicon through grain boundaries to create WAl5 and WSi2 phases, detectable even after a few hours’ immersion. Relatively soft (hardness 1.5 GPa) WAl5 formed between the W based grains, and hard (10 GPa) WSi2 outside the W based grains. Tensile strength decreased slowly with increasing immersion time, while a significant reduction in fracture strain occurred. These changes in tensile properties were caused by the microstructural changes, e.g. soft and brittle intermetallic compounds. Crack propagated along the WAl5 phases (intergranular fracture), whereas transgranular fracture was dominant for uncorroded or less corroded W90. [ABSTRACT FROM AUTHOR]

Interfacial corrosion is responsible for the strength degradation of adhesive-bonded aluminum joints (ABJs) exposed to corrosive environment. In this study, electrochemical noise and electrochemical impedance spectroscopy (EIS) measurements were performed on the aluminum alloy X610-T4PD covered with adhesive (ACA) to understand the interfacial corrosion. And environmental simulation tests (i.e. neutral salt spray (NSS) and hot humidity environment) for ABJ were carried out to investigate the joint strength degradation. Test results indicated that the variations of current and potential in the EN measurement were closely related to the initiation of corrosion in the samples. The Nyquist plots in the EIS measurement for various immersion times showed that the corrosion of ACA accelerated after about 140 h. Furthermore, a linear relationship between the residual strength of ABJ exposed to NSS and the reciprocal of interfacial corrosion resistance (Rt) of ACA was found, which was verified by ABJ exposed to hot humidity environment. [ABSTRACT FROM AUTHOR]

Protective metallic MCrAlY or diffusion type (NiAl) coatings enhance the oxidation and corrosion resistance of the underlying high temperature materials employed in aeroengines and industrial gas turbines by ensuring the growth of a slowly growing protective alumina scale. However, a chromia forming coating would provide a better resistance against sulphur induced corrosive attack. A hybrid coating system combining both chromia and alumina forming coating layers would provide optimum protection in oxidising-sulphidising environments. The microstructural stability and applicability of such a coating system (SmartCoat) containing alternate layers rich in chromium and aluminium respectively on the Ni-base superalloy CMSX-4 was evaluated after various exposure times at 800 C. Scanning electron microscopy (SEM) and electron microprobe analyses (EPMA) provided the element concentrations. Phases were identified by electron backscatter diffraction, and correlated with SEM and high-resolution TEM/EDX analyses. A computational approach was employed to describe the mechanisms of the phase transformations occurring in the coating system. [ABSTRACT FROM AUTHOR]

New palladium (II) oxaloyldihydrazone complexes are reported and characterized. The mode of bonding as well as the structure of the isolated compounds have been ascertained on the basis of data obtained from elemental analyses (CHNM), spectral (UV-Vis., IR, mass and ¹H NMR) and thermal (TG and DTA) measurements. Some optical parameters such as indirect optical band gap and refractive index were estimated for the isolated compounds. The inhibitive properties of all synthesized hydrazones toward the corrosion of carbon-steel in 1 M HCl solutions were tested. The adsorption of hydrazone inhibitors on steel surface proceeded as a spontaneous first order reaction. [ABSTRACT FROM AUTHOR]

The problem of increasing the service life of fittings made of bronzes of the BrA9Zh4N4Mts1 type is very urgent. The service life of the fittings can be doubled or increased even more by depositing sealing layers with corrosion-resisting copper–nickel alloys with more than 30% nickel. The results of investigations of the special features of the formation of the composition, structure and properties and cracking resistance of the metal, deposited with a new copper-nickel welding wire with 40% nickel of the Sv-MNZhMtsTK 40-1-1-0.3-0.1 grade on the BrA9Zh4N4Mts1 bronze are presented. In depositing the BrA9Zh4N4Mts1 wire on the BrA9Zh4N4Mts1 bronze, the deposited metal shows the formation of the Ni3Al intermetallic phase which supports the formation of cracks in the deposited metal. The experimental results show that at the aluminium content not higher than 1.5% the intermetallic phase and cracks do not form in the deposited metal. To ensure that the aluminium content of the deposited metal is not higher than 1.5% it is recommended to deposit a sublayer with the MNZhKT 5-1-0.2-0.2 wire on the bronze. The deposited metal is a solid solution of nickel, manganese and other elements of the copper-nickel alloy in copper with the crystal lattice parameter 3.661–3.666 Å. The strength of the welded joint between the BrA9Zh4N4Mts1 bronze and the metal deposited with the Sv-MNZhMtsTK 40-1-1-0.3-0.1 wire is in the range from 356 to 406 MPa, which is similar to the strength of the MNZhMtsTK 40-1-1-0.3-0.1 alloy (≥350 MPa). [ABSTRACT FROM AUTHOR]

In this study, zinc−aluminum alloy (ZA-27) matrix composites reinforced by different weight fractions of fly ash or alumina (Al2O3) were produced using the traditional stir casting technique. The corrosion behaviors of both unreinforced alloy and reinforced composites were examined using direct current polarization (DCP) test in a simulated sea solution (3.5 wt.% NaCl). Scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) were used to examine the morphology of the composites’ surface before and after corrosion tests. The results of corrosion revealed that reinforcing ZA-27 alloy by fly ash or Al2O3particles decreases its tendency to uniform corrosion due to the formation of weak microgalvanic couple between matrix and reinforcement particles. The fly ash and alumina (Al2O3) particles have protected the matrix material from pits formation at early stage of polarization. However, once these pits are formed, they grow faster. Positive hysteresis of the polarization curves implies that the salt layer breakdown and matrix dissolution overshadow surface passivation during the reverse scan. The electrochemical results are consistent with the pits’ morphology of the corroded composite. Composites with fly ash reinforcements have autocatalytic pits, whereas composites with alumina (Al2O3) reinforcements have shallow pits. [ABSTRACT FROM PUBLISHER]

Despite the fact that Titanium and its alloys are materials which have excellent corrosion-resistant properties, they have poor wear and friction performance under tribological conditions. The aim of this study is to find suitable parameters for the surface treatment of Cp-Ti substrates which are used under saline environment. In this study, TiO2coatings were grown on Cp-Ti substrates at different frequencies which are parameters of the coating process. Due to its low cost and ability to achieve high thicknesses, The Plasma Electrolytic Oxidation (PEO) method was applied to grow TiO2coatings. The microstructures, morphology, and crystallographic structure were analyzed using SEM and XRD. Tribocorrosion properties of the coatings were investigated using a combination of the pin-on-disk wear test and potentiodynamic polarization test units. The frequency is known to have a strong impact on the PEO process. The impacts of frequency changes on the PEO coating performance were examined under a constant voltage. As result, the increase of the frequency caused smaller pores and cracks in the surface morphology of the coating and at the same time this  yielded an increment on the tribocorrosion behavior of the coating. [ABSTRACT FROM PUBLISHER]

Carbon fiber-reinforced polymers (CFRPs) have attracted attention from the aerospace industry due to their light weight, excellent mechanical properties, and resistance to corrosion. However, CFRP composites are difficult to recycle as their recycling process must be performed under extreme conditions; end-of-life regulations do not directly address the problem with reusing these composites. Thus, the objective of this study is to explore solutions that minimize the use of CFRPs and prolong their useful life in the airline industry. To achieve this goal, this work conducted a review of the state of the art of CFRP fiber recycling, emphasizing the recycling processes, restrictions, and regulations. One solution is to develop a CFRP recycling market that would allow the sequential use of recycled materials among industries in descending order of the required structural performance of the composite. [ABSTRACT FROM AUTHOR]

A new chemical method for preparing a purple conversion coating on brass was developed. The effect of antimonous oxide concentration and temperature on color and corrosion resistance of the conversion coating, and the change of electric potential with time on coating forming process were studied. The optimum technological conditions were 10 g/L antimonous oxide, 20 g/L copper acetate, 200 mL/L hydrochloric acid at 65°C for 3 min. Results of electrochemical and dropping experiments showed that the brass with purple conversion coating presents better corrosion resistance than bare brass. The scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) results showed that the conversion coating mainly comprising copper and antimony was uniform and compact. [ABSTRACT FROM PUBLISHER]

The Zr-2.5% Nb alloy corrosion resistance in four saline solutions with and without albumin was tested through electrochemical measurements of electrochemical impedance spectroscopy (EIS), linear polarization, and cyclic voltammetry at human body temperature. The EIS measurements were performed at open circuit potential. The impedance spectra were recorded and the equivalent electric circuits were elaborated. From the linear polarization the Tafel slopes were recorded and the corrosion parameters were calculated. From the potentiodynamic polarization curves, the breakdown potential, the protection potential, and the protection domain were observed. The amount of ions released from the material was quantified using the ICPMS technique and the results concerning the corrosion resistance were compared with those obtained from linear and cyclic polarization. Before and after potentiodynamic polarization the topographic measurements were performed; the roughness at the samples surface was observed using AFM. The roughness was co-related to the contact angle measurements. [ABSTRACT FROM AUTHOR]

This paper reports development and testing of a novel cross-flow wet electrostatic precipitator (WESP), recently patented at Ohio University, that utilizes vertical columns of permeable material in the form of polypropylene ropes placed in a cross-flow configuration within a flue gas stream. The cross-flow design has large surface area, which provides scrubbing action; therefore, it has the potential for removing multiple pollutants, including particulates, gases, vapors, and mists. In this new method, the ropes are kept wet by the liquid (water) introduced from the top of the cells running downward on the ropes by capillary action, making the permeable materials act as the ground electrode for capturing particles from the flue gas. Preliminary testing has shown an efficiency of well above 80% using two cells and three sets of discharge electrodes. Since the material of construction is primarily corrosion-resistant polymeric material, both weight and cost reductions are expected from this new design. Implications:The newly invented cross-flow WESP exhibit particulate collection efficiency of well above 80% when introduced in particulate-laden exhaust flow. This value was obtained using a two cells and three discharge electrodes configuration. The electric field strength has a substantial effect on the collection efficiency. Also, the pressure drop test results indicate that there is a potential to increase the collection area, which, in turn, will increase the collection efficiency further. [ABSTRACT FROM AUTHOR]

Titanium is a strong, corrosion resistant metal with low mass density, making it ideal for various purposes, including aviation and medical applications. In the present work, the elastic properties of titanium have been investigated using the first principles Exact Muffin-Tin Orbitals method. The focus of our study is the anisotropic elasticity of single-crystal and cold-rolled titanium. Both types of titanium are used in industrial applications because of their special mechanical properties compared to randomly ordered polycrystalline alloys. Single crystals have better creep resistance compared to polycrystalline metals, while cold-rolled ones, on the other hand, possess more strength. Here cold-rolled titanium is investigated for the first time usingab initiocalculations. Single-crystal results are obtained directly from first principles total energy calculations, whereas the elasticity of the cold-rolled structure is estimated from the single-crystal data. The elasticity of cold-rolled titanium has previously been investigated only experimentally, and thus the present computational approach provides new insight and valuable complementary information, not only for cold-rolled titanium, but also for more complex structures. Our results are found to be in good agreement with experimental findings and therefore serve as a starting point for investigating the elasticity of titanium alloys, which, using our method, can be accomplished as easily as the pure titanium case. [ABSTRACT FROM AUTHOR]

Strands consisting of 19 parallel steel wires galvanised with zinc (Zn, 90%) and aluminium (Al, 10%) alloy were produced and accelerated corrosion tests were conducted, and the anti-corrosion performance was compared with the conventional strands galvanised with Zn. The strands were placed at a relative humidity (RH) of 60%, RH of 100% and the wet condition in the thermo-hygrostat at 40°C for 150 days. The mass loss due to corrosion of the strands galvanised with Zn–Al at an RH of 60% and 100% was small, and the strands had good corrosion resistance. The corroded mass of the strands at the wet condition was 15 times larger than that at RH of 100%. The strands galvanised with Zn–Al had lesser corrosion than those galvanised with Zn under the three environmental conditions. Corroded mass was larger in the surface wire, the inside wire and the centre wire in this order. The cross-sections of corroded strands were investigated by using a microscope and an electron probe micro-analyser showing that the corrosion product of Zn was porous and coarse. By contrast, the corrosion product of Zn–Al alloy was dense and hard to exfoliate from the steel layer. This difference made Zn–Al galvanised wire strands superior to Zn galvanised wire strands. [ABSTRACT FROM AUTHOR]

Grain boundary-engineered materials are of immense interest for their corrosion resistance, fracture resistance and microstructural stability. This work contributes to a larger goal of understanding both the structure and thermodynamic properties of grain boundaries vicinal (within) to the(coherent twin) boundary which is found in grain boundary-engineered materials. The misoriented boundaries vicinal to the twin show structural changes at elevated temperatures. In the case of nickel, this transition temperature is substantially below the melting point and at temperatures commonly reached during processing, making the existence of such boundaries very likely in applications. Thus, the thermodynamic stability of such features is thoroughly investigated in order to predict and fully understand the structure of boundaries vicinal to twins. Low misorientation angle grain boundaries () show distinctdisconnections which accommodate misorientation in opposite senses. The two types of disconnection have differing low-temperature structures which show different temperature-dependent behaviours with one type undergoing a structural transition at approximately 600 K. At misorientation angles greater than approximately, the discrete disconnection nature is lost as the disconnections merge into one another. Free energy calculations demonstrate that these high-angle boundaries, which exhibit a transition from a planar to a faceted structure, are thermodynamically more stable in the faceted configuration. [ABSTRACT FROM AUTHOR]

Duplex stainless steels are materials that present high corrosion resistance with high values of mechanical strength, therefore motivating their use in various components in the offshore industry. However, there are major challenges in the welding of these materials in terms of the productivity and quality of the joint produced, considering its extensive use for components of small thickness, such as umbilicals, to those of large thickness, such as salt water injection pipelines. In relation to pipes of small thickness, the gas tungsten arc welding process is successfully used. In thick-walled pipes, the automatic process of submerged arc welding (SAW) has been recently implemented in lines of pre-assembled piping, and this has considerably increased the productivity of the joints produced, though, a great deal of time is required to perform a new weld pass, due to the fact that the maximum interpass temperature needs to be lower than 150 °C. This work presents the results of characterization and the evaluation of corrosion resistance of a welded joint corresponding to DSS UNS S31803, with a wall thickness of 21.4 mm, welded by the gas metal arc welding process in the root and SAW process in the filling and cap passes, employing an interpass temperature between 150 and 290 °C. The results of the characterization of the mechanical properties, chemical composition and corrosion resistance in different regions of the welded joint were compared with those obtained for the base metal of the pipe, as well as with the minimum values required by the project standards. Therefore, this study has made an evaluation of the influence of the interpass temperature in the properties of the joints produced, motivated by a possible increase in productivity in pipe welding. [ABSTRACT FROM PUBLISHER]

This article presents the results of testing the intermediate layers deposited by the brush plating method. The test objects were metallic layers (Cu and Ni) and composite layers (Cu+Al2O3 and Ni+Al2O3) used to join ceramic materials with metals. The selected joining method was diffusion welding. The article presents the results of metallographic evaluation, micro-hardness testing and shearing tests of the obtained joints. [ABSTRACT FROM AUTHOR]

Based on literature sources and the author's own research, this article presents the current state of knowledge about composite coatings created by means of the plasma transfer method. The general characteristics of composite coatings and their strengthening mechanisms have been described. Methods of creating composite coatings by means of the plasma transfer method have also been discussed. [ABSTRACT FROM PUBLISHER]

Fluxes are compared and analysed and the results are used to indicate the advantage of the new flux. The new special ceramic flux for electroslag cladding of grade FTsK-18 with the welding and metallurgical properties similar to those of foreign analogues is used in the technology of single-layer corrosion-resisting strip cladding of important equipment in nuclear power stations and is fully based on domestic welding materials, and it greatly reduces the labour content and material requirement in producing corrosion-resisting coatings so that the competing capacity of Russian equipment for nuclear power stations and petrochemical industry is greatly improved. [ABSTRACT FROM AUTHOR]

The corrosion processes of mild steel immersed in river water were investigated. The reaction of the Bahlui River on common steel used in domestic and industrial installations was studied. The corrosion of mild steel is an extensive topic approached in different media, yet little information about river water as a corrosive has been reported. The experimental determinations were performed for short term immersion of four alloys in the laboratory. By using Tafel extrapolation and electrochemical impedance spectroscopy, the corrosion of the alloys was investigated. Scanning electron microscopy coupled with energy dispersive X-ray analysis and Fourier-transform infrared spectroscopy were employed to characterize the morphology of corrosion products and identify their phases. The corrosive activity of river water leads to the formation of inner compact and outer porous layers. The differences between corrosion products formed in the presence of underground and surface waters are described. [ABSTRACT FROM PUBLISHER]

This article presents the results of testing the influence of pressure on the tribological properties of single- and double-layer surfacing welds of bronze CuSn6 applied onto steel substrate by means of the MIG welding method. The welds have been created with fixed technological parameters of the surfacing process, which guaranteed an adequate quality of the welds and low content of substrate material in the weld, while ensuring sufficient adherence between the weld and the substrate. The tribological tests were conducted using the T-05 tribotester, and the results were compared with similar results obtained for cast bronze of the same chemical composition. Friction and linear wear coefficients of joints intended for sliding applications were determined in the lubricating environment of mineral and synthetic oils with pressures of 3 and 10 MPa. The tests with higher loads were designed to indicate how much pressure increase influences the tribological properties of the tested joints. The test results have shown a dependence of the friction coefficient on the number of layers in the surfacing weld and on the type of lubricating environment. Changes in the linear wear were observed for different loads and for single-layer samples compared with double-layer samples and comparative samples. [ABSTRACT FROM PUBLISHER]

316L(N) stainless steel (SS) containing 0·02-0·03 wt-% carbon and 0·06-0·08 wt-% nitrogen is the principal material for the high temperature structural components of the prototype fast breeder reactor in India. In order to increase the economic competitiveness of sodium cooled fast reactors (SFRs), there is a strong desire to increase the design life from the current level of 40 years to at least 60 years for the future reactors. As a part of the efforts to develop materials with superior mechanical properties suitable for longer design life, the influence of nitrogen at concentrations higher than 0·07 wt-%, on the high temperature mechanical properties of type 316L(N) SS is being studied. Four heats of 316L(N) SS, containing 0·07, 0·11, 0·14 and 0·22 wt-% nitrogen have been evaluated extensively in terms of their tensile, creep, low cycle fatigue and creep fatigue interaction properties. Based on these studies, the nitrogen content has been optimised at 0·14 wt-%. This nitrogen enhanced grade of steel (NE316LN SS) was found to have significantly better tensile, creep, low cycle fatigue and creep-fatigue properties as compared to the PFBR grade of 316L(N) SS. This paper presents the influence of nitrogen on the creep deformation, damage and fracture behaviour of NE316LN SS. Design of high temperature SFR components is made on the basis of RCC-MR design code. The creep properties of NE316LN SS have been analysed in terms of the procedures for generation of the design code. Time-dependent design curves have been generated. [ABSTRACT FROM AUTHOR]

The history of Ni-Co alloy deposits is summarised and recent developments are highlighted. Electrodeposition of nanocrystalline Ni-Co binary alloys and, briefly, Co-Ni-P ternary coatings is considered, including chemical composition, phase composition and crystalline nature. Nanostructure, morphology, physical and mechanical properties (including corrosion resistance) vs bath type and composition (including pH and electrolyte additives) and plating conditions, including current density, temperature and agitation are summarised. Applications range from wear and corrosion resistant coatings, particularly as a hard chromium replacement to speciality hydrogen evolution electrodes in water electrolysis. Following this extensive review, future research needs are briefly listed. [ABSTRACT FROM AUTHOR]

Corrosion resistant valve metals, such as Ti, Nb, Ta and Zr, and also their alloys are attractive as bone-substitutional materials in dental and orthopedic fields. However, they do not have high osteoconductivity, and surface coatings with bioactive substances, hydroxyapatite or TiO2, are needed for the implantation into the bone. Surface property, especially hydrophilicity, is considered to have a strong influence on the biological reactions. However, the influence of a hydrophilic surface on osteoconductivity remains unclear. In this paper, our experimental results using anodised TiO2 coatings are briefly outlined, including their in vivo evaluation. Based on these results, a comprehensive description of the factors influencing osteoconductivity is provided, and a new approach for controlling the osteoconductivity of valve metals (Ti, Nb, Ta and Zr) is discussed. [ABSTRACT FROM AUTHOR]

To reduce CO2 emissions, there is interest in a new generation of industrial gas turbines operating in advanced integrated gasification combined cycles (IGCC) with the option for pre-combustion CO2 removal systems. These gas turbines may be fired on syngas, cleaned H2 rich syngas, or natural gas, and this will alter the hot corrosion experienced by components in the hot gas path. Deposit recoat laboratory tests have looked at the response of 11 state-of-the-art materials systems under the expected IGCC conditions. MTData has been used to calculate the optimal deposits under the temperature and gas conditions for these tests. Studies of metal loss have helped assess quantitatively the resistance of the different materials systems, while microscopy techniques have given information on the degradation mechanisms experienced. Rene 80 has been selected to demonstrate the data from these tests and shows the most significant metal loss under partially cleaned syngas conditions. [ABSTRACT FROM AUTHOR]

The black microarc oxidation (MAO) coating containing Cu2+was prepared on AM50 magnesium alloys. When the additives (CuSO4and C4H4KNaO6 · 4H2O) were added into the NaAlO2solution, the color of the prepared coatings appearance changed from white to black. The effects of CuSO4concentration and treatment time on the color of the coatings were investigated. The optimum formula of black coatings prepared by MAO has been acquired by a single-factor experiment and orthogonal experiment of L9(34) with four factors and three levels. The estimated optimum values of the process parameters are corresponding to NaAlO210 g/L, C4H4KNaO6 · 4H2O 1 g/L, CuSO41 g/L, and pH 11. The surface morphologies, structure, composition, and corrosion resistance of the MAO coatings were analyzed by scanning electron microscopy, X-ray diffraction (XRD), and electrochemical tests. The results of the above series of tests have shown that the properties and characteristics of the black coatings are improved. The black coating is irregular porous structure, which aperture size is about 0.1 ∼ 0.2 µm. The black coating mainly consists of MgO, MgAl2O4, and Cu3MgO4. [ABSTRACT FROM AUTHOR]

Impression creep tests were carried out on 316LN stainless steel (SS) at various temperatures in the range 898-973 K. The stress dependence of the steady state impression velocity followed the power-law with stress exponent n = 6. The temperature dependence of the steady state impression velocity obeyed Arrhenius type rate equation. The apparent activation energy for creep deformation ( Qc) was estimated to be 500 kJ mol−1. Based on the n and Qc values, it is concluded that the rate controlling mechanism is dislocation creep. [ABSTRACT FROM AUTHOR]

Developing predictive models for quantitative assessment of the deterioration of rock bolts exposed to corrosive environments is essential for rational planning of maintenance activities for anchorage structures. This article presents a probability-based computational model for predicting the time-dependent deterioration of bond capacity of corroding rock bolts due to the attack of chlorides. The inherent stochastic nature involved in the corrosion and degradation process is identified and simulated. A method is developed based on fundamental Mohr–Coulomb theory to evaluate the effect of corrosion on the bond strength due to a failure mode involving splitting of grout cover. Parameters affecting both strength and stress state at the bolt–grout interface are quantitatively related to the degree of corrosion. Integrating the realised corrosion stochastic process and the developed bond loss evaluation method, a computational algorithm based on Monte Carlo simulation is presented for evaluating the bond deterioration in a probabilistic framework. The presented model is used in an illustrative example to show its capability to trace the evolution, throughout the entire design life, of several representative performance indicators of rock bolts as a structure unit or of the interested location within the anchor length. [ABSTRACT FROM AUTHOR]

Molybdate conversion coatings are considered as an alternative to chromium conversion coatings for improving the corrosion resistance of AZ31 magnesium alloy. In this study, the formation process of molybdate conversion coatings on AZ31 magnesium alloy was investigated using an open circuit potential curve, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The influence of processing parameters of molybdate conversion coatings was studied using electrochemical impedance spectroscopy (EIS) in 3·5 wt-%NaCl solution as a function of pH value, temperature and time. In addition, the mass gain of the coating was also monitored during formation. The results show that the conversion coatings formed at 65°C for 12 min and pH 3 have excellent corrosion resistance properties. Molybdate conversion coatings formed on AZ31 magnesium alloy exhibit a network morphology with many microcracks on the surface of the coatings. The coating is composed of O, Mo, F, Na, P, Mg and Al. The weight gain of the coating during formation follows a parabola-like curve. [ABSTRACT FROM AUTHOR]

The acicular wollastonite was prepared successfully using the NaSiO3·9H2O and Ca(OH)2 as raw materials via two-step hydrothermal synthesis and calcination methods. The scawtite and xonotlite were synthesized by two-step hydrothermal processes successively. The acicular wollastonite was prepared by the synthesized xonotlite after calcination. The hydrothermal-treated temperature, the water-solid ratio and the reaction time were studied for obtaining the xonotlite. The wollastonite powder was characterized by XRD, SEM and Differential Thermal Analysis. The results showed that the acicular wollastonite powder could be prepared efficiently after the hydrothermal treatment of 260°C for 2 hours with 6:1 water-solid ratio using the synthesized scawtite and calcination of the synthesized xonotlite by 800°C for 2 hours. [ABSTRACT FROM AUTHOR]

The main focal area of the research into deep eutectic solvents (DESs) is currently the incorporation of metal ions into solution for metal deposition, metal dissolution, or metal processing. Although difficult to compete economically with existing electroplating systems for common metal applications, DESs can provide suitable media for the many technological goals of the industry. [ABSTRACT FROM AUTHOR]

In the present study, Ni-W-Cr-P quaternary alloy coatings were prepared on titanium-based alloys by electroless deposition. The morphology, crystal structure, microhardness, and corrosion resistance of samples were studied by scanning electron microscope (SEM), X-ray diffractometer (XRD), microhardness tester, and electrochemical analyzer. The results show that the microstructure of these alloy films changes with the increase of annealing temperature. As-deposited alloy layers belong to nickel-based mischcrystal structure, and its crystallinity was enhanced to 200°C and 300°C, gradually; the new phase Ni3P began to appear at 400°C, completely crystallized at 600°C; Cr1.12Ni2.88and Ni3Ti phases were present at 700°C; Ni and Ni3P phases were totally decomposed at 800°C, and Cr4Ni15W, Cr2Ni3, Ni17W3, Cr, Cr3P, and Ni2P generated. Because of the different structures after annealing, microhardness and corrosion resistance of the alloy coatings possess a relevant change. The Ni–W–Cr–P alloy coatings heated at 600°C exhibit better microhardness and corrosion resistance than those of samples at other annealing temperature. The related mechanisms of those results were also discussed, briefly. [ABSTRACT FROM PUBLISHER]

Nitrogen in austenitic stainless steels and its effect on the stacking fault energy (SFE) has been the subject of intense discussions in the literature. Until today, no generally accepted method for the SFE calculation exists that can be applied to a wide range of chemical compositions in these systems. Besides different types of models that are used from first-principle to thermodynamics-based approaches, one main reason is the general lack of experimentally measured SFE values for these steels. Moreover, in the respective studies, not only different alloying systems but also different domains of nitrogen contents were analyzed resulting in contrary conclusions on the effect of nitrogen on the SFE. This work gives a review on the current state of SFE calculation by computational thermodynamics for the Fe-Cr-Mn-N system. An assessment of the thermodynamic effective Gibbs free energy, ▵G γ→ε, model for the γ→ε phase transformation considering existing data from different literature and commercial databases is given. Furthermore, we introduce the application of a non-constant composition-dependent interfacial energy,бγ/ε , required to consider the effect of nitrogen on SFE in these systems. [ABSTRACT FROM AUTHOR]

This paper focuses on the adherence during ageing of a primer (made of polyester resins crosslinked with melamine) applied onto hot-dip galvanized (HDG) steel for coil coating application and its influence on corrosion protection. A chromium-free surface treatment, composed of fluorotitanic acid, phosphoric acid, manganese phosphate, and vinylphenol was applied on the HDG steel to obtain high corrosion resistance and high adherence of a polyester and melamine primer. The influence of the manganese phosphate on the corrosion and adherence was investigated. To measure the adherence between the metal and the primer, a three-point flexure test was set up. The adherence was then linked with corrosion resistance during ageing, using electrochemical impedance spectroscopy. [ABSTRACT FROM PUBLISHER]

The effects of crystallization on the electron work function and corrosion resistance of Zr65Al7.5Cu17.5Ni10amorphous alloys have been studied. The single-phase amorphous alloy exhibits a better corrosion resistance and has a higher work function than the partially and fully crystallized alloys with the same composition. The close relationship between corrosion resistance and work function indicates that the Kelvin probe technique can be a powerful tool for characterizing the corrosion behaviour of amorphous alloy on an electronic level. [ABSTRACT FROM AUTHOR]

In order to improve the corrosion resistance provided by a micro-arc oxidation (MAO) coating on AZ31 magnesium alloy, a polypropylene film was prepared on its surface. Scanning electron microscopy, energy dispersive X-ray analysis and Fourier transform infrared spectroscopy were used to characterise the surfaces of the coatings. The corrosion protective performance of the coatings was evaluated by potentiodynamic polarisation curves, electrochemical impedance spectroscopy and immersion testing. The results show that the microdefects of the MAO coating can be filled by PP and the corrosion resistance of the AZ31 magnesium alloy is improved greatly. [ABSTRACT FROM AUTHOR]

An investigation has been undertaken of the influence of the mixed nanocrystalline and amorphous microstructure on the corrosion behaviour of electroless Ni-5·5W-6·5P (wt-%) deposits on steel substrates. The effects of annealing temperature on microstructure evolution were investigated. The corrosion behaviour of the deposits was evaluated by potentiodynamic polarisation in 0·5M H2SO4 solution and EIS measurements in 3·5%NaCl solution. Relationships between the microstructure and corrosion mechanisms of the as plated and the annealed deposits were considered by reference to microstructural information, including degree of crystallisation, grain sizes of both nickel and Ni3P phases, porosity development, microstrains and residual stresses. [ABSTRACT FROM AUTHOR]

Oxide films were produced on AZ31 magnesium alloy by microarc oxidation (MAO) in an alkaline phosphate solution at different concentrations of NaAlO2. Surface and cross-section morphologies were assessed by scanning electron microscopy and phase composition by X-ray diffraction. The corrosion resistance was evaluated in a diluted Harrison solution using anodic polarisation tests. The results show that the properties of the oxides are affected by the NaAlO2 concentration. The thickness of the coatings increases with aluminate concentration from 5 μm in aluminate free electrolyte to 12 μm in electrolyte containing 60 g dm-3 after anodising (5 min; 135 V). The coating consists of two layers: an outer layer with high concentration of aluminium and an inner magnesium rich layer. Increased corrosion resistance was found in the samples anodised in a solution containing 30 g dm-3 NaAlO2. [ABSTRACT FROM AUTHOR]

Cr and Cr-Al2O3 coatings were electrodeposited from Cr(III) bath with both pulsating and direct current onto copper substrates. Pulsating current resulted in homogeneous films of higher Al2O3 content and lower particle agglomeration than the direct current. Differences were more tangible at shorter duty cycles and pulse frequencies. Pulsating current improved both microhardness and corrosion resistance. The presence of alumina nanoparticles resulted in greater current efficiency, higher film microhardness and better corrosion resistance. Maximum current efficiency, highest microhardness and densest electrodeposited coatings were achieved at current density of 20 A dm-2, duty cycle of 40% and pulse frequency of 10 Hz. [ABSTRACT FROM AUTHOR]

Electron beam surfacing in an electron accelerator using powder mixtures of chromium carbides with boron carbide in different weight ratios and with different radiation parameters was used to produce wear- and corrosion-resisting coatings. It is shown that there are compositions of the surfacing mixtures and conditions of electron beam effect ensuring maximum values of wear and corrosion resistance. [ABSTRACT FROM AUTHOR]

Transition-metal dopants play a critical role in the high-temperature mechanical strength and corrosion resistance of nickel-based superalloys. In this article, the site occupancy behavior of chromium in γ′-Ni3Al has been investigated by combining three-dimensional (3D) atom probe and high-resolution transmission electron microscopy characterizations with ab initio density functional theory (DFT) calculations. The 3D atom probe data show a clear preference of chromium on the aluminum sublattice over the nickel sublattice in Rene88 super alloys. First-principles DFT total-energy calculations were performed to understand the site occupancy of chromium in the L12 structured γ-Ni3Al. The obtained chromium site preference energies have been compared using the anti-site and vacancy-based substitution formation mechanism, as well as using the standard defect formation formalism. It was found that chromium prefers aluminum site, consistent with the 3D atom probe result. In addition, interaction energies between two chromium atoms have also been determined from first-principles calculations. Our results show that chromium atoms prefer to be close by on either nickel or aluminum sublattices or on a nickel–aluminum mixed lattice, suggesting a potential tendency of chromium segregation in the γ′ phase. [ABSTRACT FROM AUTHOR]

Electrodeposited chromium coatings offer high levels of mechanical and tribological properties that justify their use in many industrial and engineering applications. However, one problem of these functional coatings is their limited corrosion resistance and the low current efficiency of their electrodeposition process. Reverse pulse plating can lead to an improvement in the characteristics of chromium deposits, but the high number of variables involved and the interactions among them make the selection of operating parameters difficult. In this paper, a chemometric approach was used in order to design the experiments and study the effect of pulse plating parameters on the properties of chromium coatings. Multivariate analysis was proposed to establish a relationship among structural and physical characteristics of chromium deposits and to determine the pulse parameters required to achieve certain properties. The results indicated that by reverse pulse electrodeposition, it is possible to obtain crack free chromium coatings, with similar hardness values as those obtained from direct current electrodeposited coatings, but with an improved corrosion resistance. [ABSTRACT FROM AUTHOR]

Ni-SiC nanocomposite coatings have been prepared by electrodeposition with the application of ultrasound at an ultrasonic frequency of 38 kHz with 200 W ultrasonic power. The observed cavitation effect due to ultrasonic application on surface morphologies, microstructures, mechanical, tribological and corrosion properties of the composite coatings were evaluated by using scanning electron microscopy, electron dispersive spectroscopy, X-ray diffraction, Vickers microhardness, and corrosion tests, such as polarisation and electrochemical impedance spectroscopy (EIS) methods. Nanoparticles obtained with homogeneous distribution and reduced agglomeration in samples subjected to ultrasound indicated significant improvements in microhardness and wear resistance of the composite coatings compared to the coatings deposited without ultrasound. Additionally, the corrosion resistance results obtained from polarisation curves and EIS methods in 3·5 wt-%NaCl solution were found to be considerably improved. There appears to be a synergistic end result of improved mechanical properties, and superior wear and corrosion resistance in Ni-SiC composite coatings with the application of ultrasound in these electrodeposits. [ABSTRACT FROM AUTHOR]

The effects of pulse plating on the phase and chemical composition, preferred orientation and surface morphology of Zn and Zn-Ni (12 wt-%) electrodeposited coatings have been investigated using atomic force microscopy, scanning electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy and electrochemical techniques. It has been established that pulse current plating with respect to direct current (dc) conditions resulted in ∼50% reduction in the grain size dimensions and in fourfold and twofold reduction in the corrosion current densities of Zn and Zn-Ni coatings respectively. Under all the pulse plating conditions applied the deposited alloy consisted of the single γ-Zn21Ni5 phase, while, according to the XRD measurements both coatings possessed inclusions of the oxide phase. The analysis of the protective properties and the thickness of the oxide films formed on the surface of investigated coatings revealed the fact that the surfaces of pulse plated samples were favourable for the formation of thinner oxide films which at the same time exhibited higher protective properties. Pulse plating increased the amount of non-metallic inclusions in Zn and Zn-Ni coatings, however, these amounts were not high, as the O concentration in the deposits did not exceed 1·5 and 0·2 wt-% for Zn and Zn-Ni respectively. [ABSTRACT FROM AUTHOR]

Anodized aluminum oxide (AAO) provides better corrosion resistance, but lowers electromagnetic interference (EMI) effectiveness. In this study, AAO was formed by anodizing aluminum in 5 wt% oxalic acid solution at 15□ for 4 hours, and metallic multi-layer coatings on AAO, such as Ni-P/Ni-B/AAO, Co-P/Ni-B/AAO, or Cu/Ni-B/AAO, were prepared by electroless plating method. The measured attenuation is greater than 50 dB in the frequency range 900–1800 MHz. The experimental results indicate that the electromagnetic interference shielding effectiveness (EMI SE) of anodized aluminum in microwave range can be greatly improved. [ABSTRACT FROM PUBLISHER]

The article offers information regarding the use of composite materials for the construction of lightweight structures gridshells. It presents several qualities of composite materials including low density, resistance against corrosion and high strength. Also discussed is the use of glass fibre reinforced polymers for lightweight structures. INSET: SEI Data Block.

In order to obtain high strength aluminium butt joints with high corrosion resistance, ultrasonic soldering of 1070 and 5056 rods was conducted using quasi-melting Zn–18Sn (mass%) alloy and Zn–38A1 alloy. Ultrasonic vibrations were applied at soldering temperature ranging 533–723 K through aluminium rods without using of a solder bath. To evaluate the corrosion resistance of solder joints, tensile tests were conducted after immersion in a 5% NaCl aqueous solution. Though joint strength decreased with an increase in immersion time in the NaCl aqueous solution because of corrosion in the joints, corrosion resistance of 5056 joints with Zn–38A1 alloy was higher than that of joints with Zn–18Sn alloy irrespective of aluminium base material. The strength of joints with Zn–18Sn alloy rapidly decreased by immersion in the NaCl aqueous solution. In these joints, corrosion occurred locally in the soldered interface. Corrosion potential of these joints was unusually lower than that of the solder alloy. In contrast, corrosion occurred slowly in the solder layer in 5056 joints with Zn–38A1 alloy. Corrosion potential of the joints was equivalent to that of the solder alloy. [ABSTRACT FROM AUTHOR]

The processes of oxide film formation on the surfaces of Zn, Zn-Co (0·6 wt-%), Zn-Fe (0·5 wt-%) and Zn-Ni (12%) coatings during anodic polarisation in bicarbonate media have been investigated. The composition, thickness, porosity and protective ability of these films were studied by applying X-ray photoelectron spectroscopy, voltammetric and electrochemical impedance spectroscopy measurements with the aim of establishing the influence of Zn alloying on the properties of the oxide layer and the nature of a higher corrosion resistance of some Zn alloys. The oxide films formed on Zn-Ni surface were found to possess a lower thickness, with respect to that of other investigated samples, but at the same time, they exhibited a higher passivating capacity. No significant difference in the composition of the inner layer of the oxide film between different samples was detected, and only the porosity of the oxide film on Zn-Ni was lower, with respect to that of other investigated coatings. It can be assumed that thinner, and at the same time, more compact (less porous), films on a Zn-Ni surface make these oxide layers more resistant. [ABSTRACT FROM AUTHOR]

The effect of a partition wall on heat transfer characteristics of a two-stream gas-to-gas counterflow microchannel heat exchanger has been numerically investigated. The flow passages of the microchannel heat exchanger are plane channels of 100 μm in height and 20 mm in length. The material of the partition wall is assumed to be stainless steel. The computations were performed for a wide range of flow rate to investigate heat transfer characteristics of the microchannel heat exchanger. Moreover, computations for various partition wall thicknesses were conducted to investigate the effect of the wall thickness. The thickness ranged from 200 μm to 6 μm while the channel height was fixed at 100 μm. Numerical results show that heat transfer characteristics of a gas-to-gas counterflow microchannel heat exchanger are affected by partition wall thickness. Computations for various partition wall thicknesses and thermal conductivities of the partition wall were performed. The results were compared with those of a single microchannel with constant wall temperature. Applicability of the assumption of constant wall temperature was revealed. [ABSTRACT FROM PUBLISHER]