Surface Of Base Metal Research Articles

Interfacial Effects of the Na Metal State on the Electrochemical Behavior on β"-Alumina Solid Electrolyte

Sodium metal is considered a promising candidate as an anode to maximize the energy density of sodium secondary batteries. The use of β"-alumina solid electrolyte (BASE) is a viable approach to ensure the safe operation of sodium metal batteries.1, 2 Although sodium metal batteries utilizing BASE have gained success at elevated temperatures (e.g. 250 °C), exhibiting stable and efficient cycling performance, even beyond 1000 mA cm−2,3 they are prone to short circuits above certain current densities, which is underscored by a crucial metric referred to the critical current density (CCD). The CCD of BASE typically varies from 0.1 to 10 mA cm−2 at room temperature,1 possibly due to insufficient contact between the rigid surface of BASE and solid sodium metal. This research focuses on the deposition and dissolution behavior of sodium metal anodes in both liquid and solid states, particularly at slight temperature differences near the melting point of sodium. The CCDs were assessed in a symmetric Na/BASE/Na cell configuration at 90 and 105 °C for solid and liquid sodium (m.p. of sodium 98 °C), respectively. The cell failure was verified by electrochemical impedance spectroscopy after each cycle. Post-test morphological characterizations of the BASE were investigated through scanning electron microscopy. Moreover, rate and cycle performance was assessed using a Na//Na3V2(PO4)3 configuration at two different temperatures. In conclusion, a slight increase in temperature to maintain sodium in the liquid state significantly bolsters the performance of the Na anode, enabling prolonged cycle duration without the dendrite formation causing cell degradation.

Mechanical and Corrosion Properties of Super Austenitic Stainless Steel Joint for Double‐Sided Synchronous TIP TIG Arc Butt Welding

Super austenitic stainless steel 254SMO (254SMO SASS) plates are joined by double‐sided double‐arc synchronous TIP TIG butt welding (DSSTTABW) using ER NiCrMo3 wire, and the micro‐structure, mechanical and corrosion properties of 254SMO SASS joints are investigated subsequently. Results show that solidification grain boundary and solidification sub‐grain boundary can be observed in fusion zone. A small amount of σ phase precipitates in the weld, while χ phase is found in the transition zone, but no solidification crack occurs in weld and heat affected zone (HAZ). 254SMO SASS joint has higher micro‐hardness and lower tensile strength and elongation compared to base metal. During transverse tensile process, 254SMO SASS joints fail in the weld zone in a ductile mode. Electrochemical corrosion performance tests indicate that 254SMO SASS joint achieve equivalent pitting corrosion resistance and similar passive mechanism to base metal in 3.5 wt% NaCl solution. The passivation film on the surface of both joint and base metal display as n‐p semi‐conductive character, but the film stability of 254SMO joint surface is slightly poorer compared to base material. The surface passivation film of 254SMO joint primarily consists of oxides of Fe, Cr, and Mo before potentiodynamic polarization, while hydroxides of Fe and Cr are also observed after polarization.

Exploring the Potential Application of an Innovative Post-Weld Finishing Method in Butt-Welded Joints of Stainless Steels and Aluminum Alloys.

The prerequisite of the weld bead finishing is intricately linked to the quality of the welded joint. It constitutes the final, yet pivotal, stage in its formation, significantly influencing the reliability of structural components and machines. This article delineates an innovative post-weld surface finishing method, distinguished by the movement of a specialized cutting tool along a butt weld. This method stands out due to its singular approach to machining allowance, wherein the weld bead height is considered and eradicated in a single pass of the cutting tool. Test samples were made of AISI 304L, AISI 316L stainless steels and EN AW-5058 H321, EN AW-7075 T651 aluminum alloys butt-welded with TIG methods. Following the welding process, the weld bead was finished in accordance with the innovative method to flush the bead and the base metal's surface. For the quality control of welded joints before and after the weld finishing, two non-destructive testing methods were chosen: Penetrant Testing (PT) and Radiographic Testing (RT). This article provides results from the examination of 2D profile parameters and 3D stereometric characteristics of surface roughness using the optical method. Additionally, metallographic results are presented to assess changes in the microstructure, the microhardness, and the degree of hardening within the surface layer induced by the application of the innovative post-weld finishing method.

Microstructural and Corrosion Behavior of Thin Sheet of Stainless Steel-Grade Super Duplex 2507 by Gas Tungsten Arc Welding

<div>Super duplex stainless steel (SDSS) is a type of stainless steel made of chromium (Cr), nickel (Ni), and iron (Fe). In the present work, a 1.6 mm wide thin sheet of SDSS is joined using gas tungsten arc welding (GTAW). The ideal parameter for a bead-on-plate trial is found, and 0.216 kJ/mm of heat input is used for welding. As an outcome of the welding heating cycle and subsequent cooling, a microstructural study revealed coarse microstructure in the heat-affected zone and weld zone. The corrosion rate for welded joints is 9.3% higher than the base metal rate. Following the corrosion test, scanning electron microscope (SEM) analysis revealed that the welded joint’s oxide development generated a larger corrosive attack on the weld surface than the base metal surface. The percentages of chromium (12.5%) and molybdenum (24%) in the welded joints are less than those in the base metal of SDSS, as per energy dispersive X-ray (EDX) analysis. Corrosion modeling is done using the COMSOL Multiphysics software. Electrochemical corrosion modeling is used to determine the electrolyte potential (i.e., 0.09 V) and current density (i.e., 0.2 A/m<sup>2</sup> to 1.8 A/m<sup>2</sup>). An entire mesh model contains 6240 elements. The largest and smallest element sizes are 4 mm and 0.1 mm, respectively. The maximum element rate of growth is 1.2.</div>

An analysis of microstructural morphology, surface topography, surface integrity, recast layer, and machining performance of graphene nanosheets on Inconel 718 superalloy: Investigating the impact on EDM characteristics, surface characterizations, and optimization

Inconel 718 finds extensive applications in the aviation and aerospace industries, particularly in the manufacturing of jet engines and high-speed airframe components like fasteners, bolts, buckets, instrumentation parts, wheels, and spacers. It is also utilised in the production of cryogenic tankage and gas turbine blades. The present study focuses on investigating the machining performance of graphene nanosheets on Inconel 718. Various aspects of Inconel 718's machinability through electrical discharge machining (EDM) have been examined, including material removal rate (MRR), surface roughness, surface morphology, tool rear Rate (TWR), residual stresses on the machined surface, Vickers hardness, and recast layer thickness. The investigation reveals a significant impact of process parameters on these machining characteristics. The effects of graphene nanosheets have been observed using several analytical instruments such as field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), particle size analyzer, and X-ray diffraction (XRD). Furthermore, optimization of the response data with respect to input parameters has been performed in this study. TEM analysis is used to determine the size of individual debris particles in deionised water and mixed graphene nanosheet dielectric mediums. To verify that the debris particles are the same as the parent material, energy dispersive X-ray spectroscopy (EDX) is used. To determine the compounds and crystal structures present in the base metal and machined surfaces, XRD analysis is used. A high-resolution X-ray diffractometer (HRXRD) is used to measure the residual stresses on the machined surface. EDX composition testing is used to analyze surface modification. Due to the rapid heating and quenching that takes place in the dielectric medium, the machined surface becomes harder. Deposited materials, microholes, and surface textures can all be observed through FESEM microstructure observation. Comparing conventional EDM to nanosheets mixed dielectric, the thickness of the recast layer is reduced. To recapitulate, the study explores how various machining parameters and dielectric mediums affect EDM processes. It examines debris particle size, compound formation, residual stresses, surface modification, hardness, microstructure, and recast layer thickness. The addition of graphene nanosheets to the dielectric medium produces promising results, reducing the thickness of the recast layer and improving surface quality. The results offer suggestions for improving Inconel 718 material surface properties and EDM machining effectiveness.

Enhancing interfacial strength of T-joint for vacuum-brazed thin-walled structures comprising TiAl and GH3536 alloys via in-situ synthesis of Al2TiO5 ceramic coatings

The joining of dissimilar materials to fabricate lightweight components of thin-walled structures for aerospace applications has garnered significant interest. A pioneering technique has been proposed to achieve an optimal interfacial microstructure and fillet of brazed joints. This technique involves a layer of Al deposited on the surface of TiAl base metal, which aids in the brazing process of the thin-walled structure comprising TiAl and GH3536 alloys. Notably, the addition of the Al layer has a significant impact on the spreading area of molten brazing filler metal, the size of the fillet, and the interfacial microstructure evolution. Consequently, these factors contribute to a substantial increase in the load-bearing capacity of the structure. A comprehensive analysis and discussion are conducted to explore the impact of the Al layer on both the interfacial microstructure and mechanical performance. Under the brazing parameters of 1040 °C/5 min, the peak tensile load reaches a peak value of 362 N, which is 100% higher compared to the joints without Al layer. It is worth noting that fracture occurred in the GH3536 foil after undergoing tensile testing. The dimension of fillet can be controlled through the in-situ synthesis Al2TiO5 ceramic phase on the surface of TiAl alloy. This research offers valuable insights into the production of engineered biomimetic materials and devices, specifically focusing on honeycomb-inspired structures.

Corrosion Behavior in Different Media of Dissimilar Super Duplex Stainless Steel 2507 and Austenitic Stainless Steel 316 Welding by Using GTAW Process with Filler Type 316L

The Super duplex stainless steel is the best of the stainless steel types because duplex stainless steel contains two phases, ferritic and austenitic, which promote this alloy's mechanical and corrosion properties compared to other types. This study will investigate the corrosion behaviour of weld metal and base metals in acidic and salty media. At 20 C, hydrochloric acid (1M, 3M, and 5M) was studied beside sodium chloride NaCl (1 wt%, 3.5 wt%, and 5 wt%). The potentiostat test results show that the effect of HCl is more aggressive than NaCl in all cases, as HCl is a strong acid. The results showed the 316 base metal being the weakest area compared with others (2507 BM and W.M.). The microstructure has been checked before and after the corrosion test and pitting corrosion has been found in the 316 base metal only, while the weld metal and 2507 base metal surfaces were free of pitting influence. Due to the welding technique and using a cooper back strip, the microstructure shows minor grain growth in the heat-affected zones (HAZ) on both weld sides. The micro-hardness test revealed that the duplex stainless steel had a higher value than the weld metal and the 316-base metal. The weld metal had a minor increase over the base metal because of the migration of the elements like chromium and nickel.

Influence of Innovative Post-Weld Finishing Method on Bead Surface Quality.

The article describes an innovative post-weld surface finishing method, which is characterized by moving a specialized cutting tool along a butt weld. The aforementioned method is unique for the machining allowance, which is treated as the weld bead height and is removed in one step with one pass of the cutting tool. The tool is equipped on one side with linearly arranged tooth-shaped cutting elements, with the adjacent teeth height changing and increasing according to the direction of the feed. The non-standard geometry of the cutting tool enables the finishing of a heterogeneous post-weld surface with increased hardness. The results of studying the 2D profile parameters and the 3D stereometric characteristics of the surface roughness using the optical method are presented in the article. Test samples were made of S235JR steel and butt welded with the MMA, MIG, and TIG methods. Subsequently, the welding bead was ground and finished in accordance with the innovative method to flush the bead and the base metal's surface. Additionally, residual stress analyses were performed using the X-ray diffraction method in the surface layers of the test samples. Based on the conducted research, the influence of the innovative finishing method on the surface quality is described.

Study on Porosity Defect Detection in Narrow Gap Laser Welding Based on Spectral Diagnosis.

As an advanced connection technology for large thick-walled components, narrow gap laser welding has the advantages of small heat input and high efficiency and quality. However, porosity defects are prone to occur inside the weld due to the complex welding environment. In this study, the influence of the process parameters and pollutants such as water and oil on the porosity defect were explored. The action mechanism of water on the electron temperature and spectral intensity of the laser-induced plasma was analyzed. The results showed that the spectral intensity during narrow gap laser welding was weaker than that of flat plate butt welding. Under the optimal welding process conditions, the electron temperature during narrow gap laser self-fusion welding was calculated as 7413.3 K by the Boltzmann plot method. The electron density was 5.6714 × 1015 cm-3, conforming to the thermodynamic equilibrium state. With six groups of self-fusion welding parameters, only sporadic porosity defects were observed according to the X-ray detection. When there was water on the base metal surface, a large number of dense pores were observed on the weld surface and in the weld through X-ray inspection. Compared with the spectral data obtained under the normal process, the relative light intensity of the spectrometer in the whole band was reduced. The electron temperature decreased to the range of 6900 to 7200 K, while the electron density increased. The spectrum variation during narrow gap laser wire filling welding was basically the same as that of laser self-fusion welding. The porosity defects caused by water and oil pollutants in the laser welding could be effectively identified based on the intensity of the Fe I spectral lines.

The wetting behavior of Al/Sn under ultrasonic action

In order to create a reliable soldering joint, the wetting behavior of the Al/Sn system subjected to ultrasonic action was quantitatively investigated utilizing a wetting equilibrium experiment. After the wetting experiment, the samples' interfacial microstructure was observed, and it was also described how ultrasonic vibration affects the wettability of the non-reactive Al/Sn system. The wetting angle dropped from 134.76° to 75.9° after the sample had been subjected to ultrasonic action for 10 s, and the liquid solder rose along the unwetted Al base metal. The oxide deposit on the base metal surface was then gradually removed by ultrasonic cavitation at the contact interface between the liquid solder and the base metal, improving the wettability of the Al/Sn system. Once the oxide films on the surface of the Al base metal has been completely removed, the wetting force no longer increases when the ultrasonic vibration period is extended. Additionally, ultrasonic cavitation can significantly speed up the dissolving of Al into liquid Sn solder. But the effect of dissolution of base metal on the enhancement of wettability is constrained. wetting force won't rise significantly as dissolution increases.

Corrosion and Corrosion Protection of Copper Sculptures by Formation of Composite Barrier

Nitrogen dioxide, carbon dioxide and sulphur dioxide are acidic gas and they produce corrosive medium for copper sculptures. These gases absorb moisture to form nitric acid, carbonic and sulphuric acid. It forms corrosion cell on the surface of copper and accelerate corrosion reactions. The corrosion cell formation is written as: Cu|Cu2+||H+|H2 thus corrosion reactions start and copper is oxidized into Cu2+surface and it is oxidized into Cu2+ whereas H+ ion is reduced into H2 . Nitric acid environment copper exhibits galvanic, pitting, stress, crevice, blistering, embrittlement and intergranular corrosion. The corrosion reactions change physical, chemical and mechanical properties of corroded materials. Nanocoating compound tetrahydrodibenzo[a,d][7]annulene-5,11-disemicarbazone and SiC electrospray compounds used to control the corrosion of copper in nitrogen dioxide medium. For corrosion mitigation of copper metal interface was coated with tetrahydro-dibenzo[a,d][7]annulene-5,11-disemicarbazone and SiC. The coating compound tetrahydro-dibenzo[a,d][7]annulene-5,11-disemicarbazone was synthesized in laboratory. Nozzle spray techniques used for nanocoating and electrospraying. The corrosion rate of copper was determined by gravimetric loss method at different temperatures, concentrations and days in nitrogen dioxide medium. Potentiostatic polarization technique used for the determination of electrode potential, corrosion current and current density. Nanocoating and electrospraying compounds formed a composite barrier on the surface of base metal by chemical bonding. The nanocoating and electrospray compounds adhered on base metal by chemisorptions to confirm by activation energy, heat of adsorption, free energy, enthalpy and entropy. The nanocoating and electrospray deposited on copper confirmed by Langmuir, Frundlich and Temkin isotherm. Copper formed a complex compound to interact with tetrahydro-dibenzo[a,d][7]annulene-5,11-disemicarbazone and SiC. Electrospraying SiC blocked porosities of nanocoating compound and checked osmosis process of nitrogen dioxide. Thenanocoating and electrospray compounds decreased corrosion rate and increased surface coverage areas and percentage coating efficiencies.

Effect of pumping gas on temperature field and pressure in hollow tungsten arc

A hollow tungsten negative pressure arc (HTNA) is a heat source that controls the gas flow inside a tungsten electrode and optimizes the arc output. However, to ensure the widespread applicability of HTNAs, the factors affecting the temperature and pressure distribution of an HTNA should be studied. In this study, the effect of pumping gas on the temperature and pressure distribution of an HTNA is elucidated through experiments and numerical simulations. A double spectral line acquisition system with nine optical transmission fibers was used to obtain the arc light intensity for the temperature calculation and spatial reconstruction. Consequently, a unified numerical model was developed to quantitatively study the physical field distribution under the effect of pumping gas. It was observed that the maximum temperature of the traditional gas tungsten arc (GTA) and hollow tungsten arc (HTA) decreased more than that of the HTNA owing to the effects of pumping gas. By analyzing the current density and flow field, it was concluded that convective heat transfer owing to pumping gas is the primary cause of the temperature difference between the arcs rather than Joule heat. Compared with the effect of the Lorenz force, the arc flow had a more significant effect on the pressure difference between the inner and outer tungsten electrodes. The gas in the arc region flowing into tungsten also affected the arc pressure on the base metal surface. The results of this study are expected to provide guidance for controlling the energy output of the welding arcs.

Micro engraving on Ti-6Al-4V using fiber laser for orthopedic implant-A study

The demand for production of fine micro-grooves with least heat-affected zone (HAZ), recast layer thickness, microcrack, and microcavity are increasing as Ti6Al4V is a readily used orthopedic implant material. This study presents a groove quality optimiser called response surface methodology (RSM) for fiber laser micro engraving on Ti6Al4V to improve microgroove quality and functionality. The critical process factors’ (number of laser beam passes, scan speed, and pulse frequency) for each response characteristic are identified through the RSM optimiser by analysing the experimental data sets. The optimised data sets are beneficial in maintaining groove quality characteristics (width, depth, HAZ, recast layer thickness, and microhardness). Number of passes and scanning speed has been recognised as crucial process parameters that primarily regulate the groove response characteristics. A 3-20-5 neural network (NN) model is developed and trained through the experimental input–output data sets. Performance of 3-20-5 model is found as 1.63e-27, and regression score is significantly closer to 1. It has been recognised that ANN model predicts more accurate results with a low error percentage than RSM model even when the input factor level settings are beyond the defined boundary. Under these experimental settings, the microgroove characteristics are enhanced in terms of low HAZ, recast layer thickness, microhardness, and spatter. X-ray diffraction analysis (XRD) is also performed on base metal and grooved surfaces to determine diffraction peaks, crystallite phase composition, size, and lattice strain. XRD analysis revealed the presence of both HCP-α-Ti and BCC-β-Ti in both base metal grooved surfaces.

Study for Improvement in the Surface Properties and Wear Behavior of Mild Steel

Abstract: Surface of a material can be improved by depositing the filler metal for the enhancement of various properties. Surface should be harder than substrate material for surface improvement. This surface improvement is also known as surfacing. In present research Mild steel specimens of size 140×35×40 were used to deposit surfacing layers and study the feasibility of iron/aluminum with varying compositions on low carbon steel deposited by GTAW process. Specimens for hardness and oxidation resistance were prepared. While studying oxidation of surfaced and un-coated area (base material), oxidation test resulted that the oxidation occurred on surface of base metal (un-coated area) after heating at different temperatures and time intervals. Specimens kept at 500˚C, 700˚C temperatures for 3, 6, 9 hours to get oxidized from un-coated surface but no mark of oxidation and pitting was visible at surfaced area but pitting of un-coated area occurred at 700˚C temperature. Oxidation had no effect to surfaced area. Low temperature oxidation test specimens gave only weight loss from un-coated portion but high temperature oxidation gave high amount of weight reduction due to pitting occurred on un-coated portion. The amount of weight loss of specimens increased with increase in furnace holding time at constant temperature. With increase in temperature oxidation of un-coated area of specimens also increased and pitting action occurred on un-coated area of specimens at high temperature. Further, for the various wear tests the cylindrical pins of 8 mm diameter with spherical tip 4 mm radius was made. Wear tests were carried out on pin on disc sliding wear testing machine. The comparison of wear rate loss was studied with constant sliding distance, varying load and sliding velocity of different compositions of iron/aluminum surfacing and substrate material. Hardness and wear resistance of composition were increased with increase in percentage of Fe element in composition. Composition C1 (Fe:Al/70:30) had high hardness and high wear resistance as compared to composition C2 (Fe:Al/30:70) and C3 (Fe:Al/50:50). Composition C3 (Fe:Al/50:50) had better hardness and wear resistance as compared composition C2 (Fe:Al/70:30). Keywords: Surface improvement, Fe-Al intermetallic, GTAW process, Sliding wear.

Effects of nickle, nickle-cobalt and nickle-cobalt-phosphorus nanocatalysts for enhancing biohydrogen production in microbial electrolysis cells using paper industry wastewater

Paper industries are water-intensive industries that produce large amount of wastewater containing dyes, toxicity and high nutrient content. These industries require sustainable technology for their waste disposal and MEC could be one of them. However, effective MEC operation at neutral pH and ambient temperature requires economical and efficient cathodes that are capable to treat indusial wastewater along with recovery of energy/biohydrogen. Co-deposits of Nickel, Nickel–Cobalt and Nickel–Cobalt–Phosphorous on the surface of SS and Cu base metals distinctly were used as cathodes in MEC for the concurrent treatment of real paper industry wastewater and biohydrogen production. MECs were utilized in batch mode at neutral pH, applied voltage of 0.6 V and 30 ± 2 °C temperature with paper industry wastewater and activated sludge as microbial sources. The fabricated Nickel–Cobalt–Phosphorous gives the higher hydrogen production rate of 0.16 ± 0.002 m3(H2) m−3d−1 and 0.14 ± 0.002 m3(H2) m −3d −1 respectively, with ~33–42 % treatment efficiency for a 500 ml wastewater in 7-day batch cycle in both the cases; while it is lowest in the case of the control cathodes (SS1 (0.07 ± 0.002 m3(H2) m−3d−1) & Cu1 (0.06 ± 0.004 m3(H2) m−3d−1)). It was also found that fabricated cathodes have the capability to treat industrial wastewater at ambient conditions efficiently with higher energy recovery. Prepared cathodes show enhanced hydrogen production and treatment efficiency as well as are competitive to some reported literature.

Bead geometry modeling on uneven base metal surface by fuzzy systems for multi-pass welding

This paper presents a modeling method of weld bead profiles deposited on uneven base metal surfaces and its application in multi-pass welding. The robotized multi-pass tungsten inert gas welding requires precise positioning of the weld beads to avoid welding defects and achieve the desirable welding join since the weld bead shapes depend on the surface of the previously deposited beads. The proposed model consists of fuzzy systems to estimate the coefficients of the profile function. The characteristic points of the trapezoidal membership functions in the rule bases are tuned by the Bacterial Memetic Algorithm during supervised training. The fuzzy systems are structured as multiple-input-single-output systems, where the inputs are the welding process variables and the coefficients of the shape functions of the segments underlying the modeled bead; the outputs are the coefficients of the bead shape function. Each segment surface is approximated by a second-order polynomial function defined in the weld bead’s local coordinate system. The model is developed from empirical data collected from single and multi-pass welding. The performance of the proposed model is compared with a multiple linear regression model. During the experimental validation, first, the individual beads are evaluated by comparing the estimated coefficients of the profile function and other bead characteristics (bead area, width, contact angles, and position of the toe points) with the measurements, and the estimations of a multiple linear regression model. Second, the sequential placement of the weld beads is evaluated while filling a straight V-groove by comparing the estimated bead characteristics with the measurements and calculating the accumulated error of the filled groove cross-section. The results show that the proposed model provides a good estimation of the bead shapes during deposition on uneven base metal surfaces and outperforms the regression model with low error in both validation cases. Furthermore, it is experimentally validated that the derived bead characteristics provide a suitable measure to identify locations sensitive to welding defects.

Effect of Multi-pass SMAW Welding on the Surface Hardness and Microstructure of Carbon Steel AISI 1050

The objective of this work is to investigate the chemical composition, mechanical, and metallurgical properties of welded the carbon steel plates by electrode E7Cr utilize a shielded metal arc welding (SMAW) to weld three cases include one, two, and three passes. The material of the carbon steel plate was of type AISI 1050 with a thickness of 18mm, the diameter of the electrode was 3.2mm. A surface welding was used as a deposit on the surface of base metal with welding parameters of welding current = 90-140A, voltage = 21V. The welded workpiece was tested by a chemical composition analysis, Vickers hardness test, and microstructure test. The results refer that the chemical composition analysis of deposited weld metal achieved an increase in the alloying element of C, Cr, and Mn. The microstructure test of welding zone gives the microstructure different of the base metal, which it consists of a mixture of fine-grain Ferrite, dendrite, coarse dendrites, and Cr-carbide, especially in the third pass. The Vickers hardness test of the third layer had an estimate much higher than of the other layers.

Verification of corrosion inhibition of Mild steel by some 4-Aminoantipyrine-based Schiff bases – Impact of adsorbate substituent and cross-conjugation

Corrosion inhibition of mild steel (MS) by a series of 4-aminoantipyrine-based Schiff base has been studied in 1 N HCl aqueous medium adopting electrochemical method at different concentration (10-2–10-5 M) and temperature (303–333 K). All of the inhibitors were found to be dominated by cathodic/anodic in nature (mixed type). Electrochemical impedence and polarization studies were in agreement with each other. The surface morphology (smoothness and roughness) was characterized by SEM, which indicates the formation of protective layer on the MS surface. The substituents on the Schiff bases influence their corrosion inhibition properties.Schiff bases having OCH3, OH and NMe2 substituents exhibit more inhibition tendency as compared to other substituents. The role of cross conjugation in electron donating as well as accepting properties by heteroatom (N, O) and π-electrons in corrosion inhibition was clearly observed from DFT calculations. Monolayer formation on the MS surface has been confirmed from the Langmuir isotherm fitting. Thermodynamic modeling has been done to understand the nature of adsorption. The values of ΔG (>−30 kJ/mol/K) indicate the existence of both physical and chemical interactions between the Schiff base molecules and metal surface.

Electron beam surface heating-diffusion bonding: An effective joining method for aluminum alloy metal-matrix composite with high SiC volume

As a novel method to reduce the temperature during electron beam welding, and to subsequently inhibit interfacial reaction between SiC and Al matrix, the electron beam surface heating - diffusion bonding is proposed for joining SiC particle reinforced aluminum alloy metal - matrix composite of 45 vol.% SiC/2024 Al. The defocused electron beam was used to heat the base metal surface, and the simultaneous pressure was applied to the butt surface to achieve bonding. The base metals were successfully joined by diffusion. The maximum temperature of the whole joint was effectively decreased to less than 650 ℃. The Gibbs free energy change of interfacial reaction was calculated, meaning a positive value reaching 218 kJ/mol and a consequently prominent inhibitory effect on the formation of brittle Al4C3 that was proved by microstructural observation. The tensile strength for the bonded joint was increased by 35 % compared to that for ordinary welded joint. When the TC4 layer was added, TiC strengthening particles were formed with the deficiency of Al4C3, corresponding to the significantly increased tensile strength of 63 % of base metal (154 MPa).

Various current and electrolyte solutions of electroplating for medium carbon steel towards coating performance as corrosive protection

Electroplating is utilized to protect metals from environmental influences. This study aims to determine the effect of solution composition and electric current on coating thickness and to observe morphology with nickel plating. The electrical currents were set in 0.5A, 1A, and 1.5A. Meanwhile, the electrolyte solutions consist of NiSO4, NiCl2, H3BO3, H2O, and were added in different compositions. In this research, several characterizations were conducted to measure the thickness of the coated layer using a micrometer. SEM (Scanning Electron Microscopy) was used to observe the surface morphology. The thickness test is shown that the higher current obtained the thicker coating layer. Moreover, the higher compositions of electrolyte solutions affect more coating layer on the base metal surface. The rough surface was depicted on metal coated in low current. New iron-nickel and iron-nickel-oxide was detected by X-Ray Diffractometer (XRD) as Fe0.64Ni0.36 and NiFe2O4.