Acid Bath Research Articles

A correction scheme for calcium carbonate clumped isotope (Δ47) thermometric equation depending on sample preparation technique

The CO2 preparatory methods implemented during carbonate-clumped isotope analysis for the acid digestion of carbonate with the goal of high sample throughput yielded multiple empirical relationships for the thermometry. These methods varied significantly from its original practice of carbonate reaction at 25 °C using sealed vessel method to automated quick performance acid drip or common acid bath method at 70 °C or 90 °C temperatures, respectively; these approaches differed noticeably. Technical development replacing primitive reaction protocols, introduced different reaction conditions, causing significant differences in the chemical reaction procedure and CO2 trapping, which caused variation in the values of slope and intercept for the linear regression equations governing carbonate-clumped isotope(Δ47) distribution with carbonate growth temperatures. These studies include the Δ47 measurement and analysis of either laboratory-grown or natural carbonates with precise knowledge of their precipitation/depositional temperatures. However, the discrepancies in the existing universal calibration schemes remained poorly understood despite adopting an identical data correction protocol. This is explained here by the reaction kinetics and CO2 collection methodologies adopted during experimentation. The present study investigated the slope and intercept values of the published carbonate clumped isotope thermometry equations expressed in the accepted Absolute Reference Frame (ARF in CDES) at 25 °C after accounting for the acid correction factor. We observe a systematic shift in the mean slope and intercept values of 0.0154(±0.007) and 0.153(±0.0686) ‰ for 70 °C reaction experiments and offset of 0.0181(±0.008) and 0.197(±0.079) ‰ for the experiments conducted at 90 °C by using the acid drip and/or Common Acid bath method, respectively from the slope and intercept values of the calibration equations proposed using sealed vessel method at 25 °C reaction temperature. The mean values for slope and intercept are compared using ANOVA and paired f-test. These correction factors for slopes and intercepts will allow the transformation of clumped isotope values at different temperatures into ARF scale at 25 °C and enable accurate deduction of temperature for carbonate samples. Correction factors proposed here account for variations in the sample preparation techniques arising due to different reaction temperatures, mechanisms and vapor pressure in the chamber for isotopic exchange reaction to happen for smaller or prolonged time intervals.

Electroless Ni-P-MoS2 composite coating of Al-alloys: effect of surface textures and bath composition

Abstract The present work assesses the effect of textures and bath composition on Ni-P-MoS2 electroless composite coating. Aluminium alloys are subjected to textures (through electrical discharge machine) for using as substrate material in the present context of study. A comparison study is conducted to evaluate the effect of coatings on textured and non-textured surfaces prepared in two different baths (oxalic acid and hydrazine). Different surface characterization has been carried out including micro-hardness, surface roughness, topography, morphology, tribology through micro-scratch test, and composition analysis (using Energy Dispersive Spectroscopy) in the study. Results indicate that the textured coated surfaces impart better wear-resistant properties than those of coatings produced in non-textured ones. Moreover, the coating prepared using oxalic acid bath imparts better micro-hardness and tribological properties than those of hydrazine bath. The elemental presence of Mo, S, Ni and P was affirmed through EDS mapping, indicates transference of MoS2 particles on to the coated surfaces. The micro-hardness of different coated specimen prepared using oxalic acid bath range from 53.55 HV0.2 to 71.31 HV0.2 for non-textured samples and 70.47 HV0.2 to 113.52 HV0.2 for textured ones. It varied from 53.68 HV0.2 to 68.85 HV0.2 for non-textured surfaces and 63.03 HV0.2 to 98.27 HV0.2 for textured surfaces in hydrazine bath. The addition of MoS2 powder in the electroless bath account for the deposition of a tribo-adaptive layer on Al-alloys.

A comparative study on metal pollution from surface dust of informal and formal e-waste recycling sectors in national capital region of New Delhi and associated risk assessment

Electrical and electronic waste (e-waste) is considered as resource and secondary source of metals, and is being recycled for recovery of precious and base metals. But the processes of recycling and the waste generated during e-waste recycling in informal and formal sectors contribute toxic metals in to the environment. This work aimed to compare the environmental and health impacts of informal and formal e-waste recycling facilities at New Delhi and Bhiwadi Industrial area in India, respectively. Here, concentrations of Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn, V, Zn, and Ag, and As in surface dust collected from informal and formal recycling sectors and their associated pollution, human health and ecological risk are presented. Metal concentrations were higher than the background levels in both sectors. Contamination factor (Cf), contamination degree (Cdeg), pollution load index (PLI), geo-accumulation index (Igeo) and enrichment factor (EnF) of metals indicated severe pollution levels in both sectors. However, contamination in informal sector was comparatively higher than the formal sector. Sampling sites in both sectors had very high ecological risk. Storage, dismantling/shredding and recycling techniques were contributors of metals in surface dust in formal sector whereas fumes deposition, re-suspension, and dried by-products during acid bath treatments were additional sources in informal sector. Metal pollution depends on metal(s), e-waste type(s) and recycling sector(s). Total non-carcinogenic health risk due to metals was 6.5E+00 and 6.0E+01 and 6.2E+00 and 5.5E+01 in adult and children in informal and formal sectors, respectively. Total carcinogenic risk was 3.3E-03 and 7.2E-03 in informal and formal sectors, respectively. Ingestion was major pathways of metals followed by dermal and inhalation and children were more prone to risk compared to adults. Formal sectors too cause metal pollution but to lesser degree compared to informal. More effective pollution control measures are required in formal sector to control environmental pollution.

Systemic Economic Viability of Informal Sectors: E-Waste Management

The informal sector has been at India’s core of recycling WEEE for the last few decades. They do not have the scientific knowledge of processing e-waste and use acid baths and heat treatment to extract precious metals. The existing processes used by informal actors lead to a serious impact on their health as well as the environment. The introduction of advanced recycling technology for mitigating the hazardous effects on the environment and human health is as important as the development of technology for new-age electronic products. The social, economic, and environmental benefits to the informal sector can ensure formalized livelihoods in e-waste recycling by ensuring access to technology. The paper highlights how setting up a recycling facility and capacity building of the informal sector solves the problem of informality and its associated social, economic, and environmental evils, which will benefit the sector as a whole.

Fabrication and optical characterization of zinc telluride thin films using electrodeposition technique

A well adherent thin film of Zinc Telluride (ZnTe) has been deposited on Flourine doped Tin oxide glass substrates from acidic baths containing Zinc heptahydrate and Tellurium dioxide. Films of different thicknesses with their molar concentrations were obtained. A mini Schimadzu UV-VIS Spectrophotometer was used to determine the optical absorbance of the films over the wavelength range of 300-900nm at room temperature. There is a decrease in absorbance as the molar concentrations of the precursors increases; while transmittance and energy band gap shown an increase. The band gap values obtained varied between 2.10eV and 2.7eV, for as deposited films. Also, photoelectrochemical cell (PEC) measurement reveals that ZnTe thin films exhibit p-type conductivity.

MORPHOLOGICAL CHARACTERISTIC OF VIERUL LOCAL GRAPE (Vitis spp.) CUTTING SEEDS ON PODZOLIC SOIL USING VARIOUS CONCENTRATION OF AUXIN SOAK

The development of grapes (Vitis vinifera) has obstacle among others are limited optimal land and difficult nurseries. Suboptimal land use for grape cuttings can use red yellow podzolic soil (ultisol). Podzolic soil has an acidic pH and low macro and micro nutrient uptake but can still be used as a growing medium. Vierul local grapes are a type of grape that has begun to be developed as root stock in nurseries but needs to be improved for its root success using a synthetic phytohormones bath of napthaline acetic acid (NAA). The purpose of this study was to determine the morphological character of vierul local grape cuttings at various concentrations of NAAsoaking in podzolic soil growing medium. This research has been carried out in a screen house from August to December 2021. This study used a non-factorial completely randomized design (CRD) with 3 treatments and 3 replications as block consisting of F0, F1, F2, F4 following by 0, 2, 4, 6 g L-1 respectively. The morphological characteristics observed is number of bud break, time of leaves appear, number of leaves, tendril length and percentage of live cuttings. The results of the study were analyzed using ANOVA at the 5% level and continued using the DMRT at the 5% level. The result showed that soaking of NAA at a concentration of 0 g L-1 (F0) had the best result for the variable number of bud break and number of leaves. Concentration of 6 g L-1 (F3) had the best result for variable length of the tendril while for the variable when the leaves appear, NAA soaking has no significant effect. The percentage of live cuttings is still low because it is influenced by the quality (material) of cuttings, the age of woodstock, growing media and water availability.

Electrochemical preparation and alkaline water splitting activity of ternary Co–Fe–Mo non-crystalline coatings

The influence of Na2MoO4 concentration on the electrochemical deposition of Co–Fe and Co–Fe–Mo alloy coatings from slightly acidic citrate baths and their electrocatalytic performance for alkaline water electrolysis in 1 M NaOH solution have been examined. The chemical composition and the evolution of the crystallographic structure have been analyzed by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), and scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) measurements. Increasing concentration of Mo in the alloy led to gradual amorphization of the crystalline structure. Electrochemical studies revealed that the cathodic Tafel slope reduced to 69 mV/dec for Co–Fe–Mo alloys. Furthermore, a low overpotential value of −121 mV was observed from polarization studies, which confirmed a good catalytic activity for the alkaline water splitting process.

PH‐Dependent Synthesis of Pure‐Phase BiI3 and BiOI by Electrodeposition**

AbstractThis study reports the electrochemical synthesis of different morphologies of bismuth iodide and bismuth oxyiodide on graphite surfaces from acidic baths containing bismuth nitrate, sodium nitrate, iodine and ethylene glycol by a simple pH control. Linear sweep voltammetry analyses determined the potential window for the reduction of iodine where bismuth ions do not get reduced. The concentration of the iodide ions in the bath is regulated by the applied potential. At pH 0.2 and 0.5, bismuth is predominantly present as free Bi3+ ions, which react with iodide to form bismuth triiodide. On the other hand, even at slightly elevated pH 1.0 and 2.0, bismuth is predominantly complexed by water, nitrates and ethylene glycol. These complexes react with the iodide ions to form bismuth oxyiodide. Pure triiodide phase comprising polygonal platelets is obtained at pH 0.2. Pure oxyiodide phase comprising novel microflower‐like morphology formed from interlinked nano‐disks is obtained at pH 2.0.

EFFECT OF SHOT PEENING DURATION ON FATIGUE LIFE OF GALVANIZED AND NON-GALVANIZED PEARLITIC HIGH STRENGTH HELICAL COMPRESSION SPRINGS

In this study, the effect of shot peening duration on the fatigue life of galvanized and non-galvanized springs was investigated. As the shot peening duration increased, the fatigue life of the compression springs decreased due to several embrittlement mechanisms on the spring surface. The surface roughness almost linearly increased with increasing shot peening durations. The best fatigue life was obtained with shot peening durations of 10 and 20 min for non-galvanized and galvanized springs, respectively. The non-galvanized specimens exhibited better fatigue performance than galvanized springs. The main reason for the decrease in the fatigue performance of galvanized springs is hydrogen embrittlement behavior. Free hydrogen generated in the acid bath during the galvanizing process is entrapped between the surface and the zinc layer. As a result, the compression strain that reflects crack onset and propagation was adversely affected by hydrogen embrittlement behavior.

Гальваношламы – источник вторичных материальных ресурсов при получении пигментов-наполнителей для лакокрасочных изделий

Galvanic production occupies one of the first places according to the degree of negative impact on the environment due to the content of heavy metal ions which have toxic, carcinogenic and mutagenic properties. Finding an effective method of recycling and utilization of galvanic sludge will solve the problem of the steady growth of the cost of metals and minimize the negative impact on the environment, which is an important environmental task of great scientific and practical significance. This paper presents the results of studies on the extraction of iron oxide(III) Fe2O3 from ironcontaining galvanic sludge to use it as a filler pigment in the manufacture of paint (red iron oxide). At the initial stage, the original galvanic sludge was dissolved in distilled water to a creamy consistency, and then, sulfuric acid was gradually added until the pH value gradually decreased (pH 6.0–1.5), metal sulfates were obtained. Iron hydroxide(III) Fe(OH)3 was precipitated from filtered sulfate solutions with 40% NaOH alkali solution at pH 1.5–4.1. After preliminary drying at a temperature of ≈ 150 оС, heat treatment was carried out at 600±2 оС for 5–6 h, obtaining iron oxide(III) Fe2O3, which met the requirements of GOST 10503-71 “Oil paints, ready to use. Technical Conditions in terms of particle size, oil capacity, particle density and pH of aqueous extracts. The iron minium paint made on its basis also met the requirements of this GOST on parameters: viscosity, hiding power, drying time, etc. A schematic diagram is proposed for obtaining a filler pigment used for the production of paints and varnishes. The scheme uses a set and layout of equipment widely used in industry (conveyor, batchers, screw feeders, acid and alkali treatment baths, centrifuge, drying and roasting oven).

Ultrathin ultrastrong transparent films made from regenerated cellulose and epichlorohydrin

Thin films used in electronic devices are often petroleum-based, non-biodegradable, and non-renewable polymers. Herein, ultrathin ultrastrong regenerated cellulose films were made with a facile method by applying a solution of mildly carboxylated nanocellulose and various amounts of epichlorohydrin (ECH) as a crosslinker. The morphology and physiochemical properties of films were measured using FE-SEM, TEM, FTIR, NMR, UV–Vis, XRD, DLS, and TGA. Carboxylated cellulose with a charge content of 1.5 mmol/g was prepared to make alkaline dopes containing nanocrystalline cellulose (CNC). Then, ECH (0–50%) was added and the dope was blade cast, dried in an oven, regenerated in an acid bath, washed, and air dried to make uniform films approximately 1 μm thick. The tensile stress and elastic modulus of the films were measured and found to be 100–300 MPa and 5–12.7 GPa, respectively. Higher amounts of ECH led to stronger films. All films were over 96% transparent, insoluble in water, and absorbed 24–28% moisture. TGA analysis showed ultrathin films were thermally resistant up to 250 °C and were stable and unchanged over a month at 105 °C showing excellent thermal aging resistance. Overall, films with 5–10% ECH are extremely strong, which makes them promising bioresource-based candidates for flexible electronic applications.

Facile synthesis of porous cellulose aerogel beads with tunable core–shell microstructures and physical properties

Cellulose aerogel beads (CABs) have emerged as advanced biomaterials with numerous engineering applications, including chromatography and drug release. In this study, porous core–shell CABs were synthesized using a dilute ethanol solution-substitution-assisted freeze-drying. The formation mechanism of the CABs and the effect of ethanol concentration on the core–shell microstructures and physical properties were investigated. Cellulose hydrogel beads (CHBs) were formed through the exchange/neutralization of acetic acid with tetraethylammonium hydroxide (TEAOH)/urea. The cellulose chains dissolved in the cellulose–TEAOH/urea droplets regenerated from the edge to the inside of the droplet in an acetic acid bath. Notably, adding ethanol at a concentration of 10% before freeze-drying can result in core–shell CABs with non-obvious structural shrinkage, large particle size, uniform pores, and high porosity. Ethanol molecules induce ice crystal growth to form more uniform ice crystals during the freezing process. Additionally, by altering the TEAOH/urea molar ratios and cellulose concentrations of cellulose solutions, well-shaped and porous CABs were prepared, demonstrating the feasibility and availability of dilute ethanol solution-assisted freeze-drying. Consequently, the as-fabricated CABs had a dense micro-shell (1–9 μm) and loose millimetric-core with anisotropic pores (2–6 μm), exhibiting low density (0.06–0.09 g/cm3), high porosity (87.0–91.5%), and noteworthy thermal stability.

Insights into the synergistic effects of safranine in an acidic copper bath on through-hole void-free filling for high-quality electronics interconnection

In this work, we develop a novel safranine (SA)-based acidic sulfate copper electronic plating process for through-hole copper void-free filling for high-quality electronics interconnection, and both the molecule actions and synergistic effects of safranine (SA) are carefully explored. Cyclic voltammetry experiments at rotating rates of 200 r/min and 1200 r/min demonstrate that SA itself can accelerate the electro-reduction of copper ion, heighten the inhibiting effect of polyethylene glycol (PEG) and acceleration effect of bis-(3-sulfopropyl) disulfide (SPS). The addition of SA to the virgin make-up solution (VMS) containing PEG and SPS makes the relative electric charge (∆Q) between the low and high rotating rates be increased from 1.27 ± 0.04–22.53% ± 0.05, indicating the higher copper electronic plating amount at the center than that at the mouth of through-hole. In situ Fourier transform infrared spectroscopy together with theoretical calculations further illustrate that the molecule SA is adsorbed on the copper surface through the N atom in the aromatic ring, PEG and SPS can heighten the adsorption of SA on the Cu surface, and both PEG and SPS both synergistically influence with SA to achieve the void-free copper filling of through-hole.

Green Approach for Electropolishing Surface Treatments of Additive Manufactured Parts: A Comprehensive Review

Over the years, the widespread diffusion of additive manufacturing, especially to produce metal objects, and the awareness of their poor surface quality due to the presence of a significant roughness, have highlighted the need to develop suitable post-processing surface treatments. In this regard, electropolishing techniques are ideal due to their high versatility, even on geometrically complex or small-sized objects, which are difficult to treat with techniques that require physical contact with a tool. On the other hand, the common use of strong and dangerous acid baths does not allow compliance with increasingly stringent sustainability criteria. For this reason, special attention is increasingly directed toward the identification of green electrolytes, based on deep eutectic or acid-free solvents, potentially capable of replacing conventional acid solutions. The choice of new environmentally sustainable and specifically appropriate solvents according to the metal alloys treated could allow a further expansion of the additive processing technologies, and therefore preserve their advantage, extending, among other things, the demand for the related finished products thanks to their superior aesthetic and functional quality.

Hydrogen Bonding Enables Polymer Hydrogels with pH-Induced Reversible Dynamic Responsive Behaviors.

Poly(acrylic acid-co-N-vinylcaprolactam) (PAN) hydrogels containing multiple hydrogen bonds can exhibit pH-induced reversible dynamic responsive behaviors. When placing a transparent hydrogel in an acid bath, as hydrogen bonds between comonomer units involving protonated COOH groups are formed faster than water diffusion, a nonequilibrium light-scattering state is formed to turn the hydrogel opaque, while as the swelling equilibrium is reached over time, the hydrogel regains its transparency. Likewise, when the transparent, hydrogen-bonded hydrogel is subsequently immersed in DI water, faster water absorption occurs in where more COOH groups are deprotonated, which also generates a light-scattering state leading to opacity, while the transparency is slowly recovered after equilibrium. Using such two-way dynamic transparency evolution, a PAN-based hydrogel material is prepared to demonstrate a dynamic memory system for information memorizing-forgetting and recalling-forgetting.

Hydrogen Bonding Enables Polymer Hydrogels with pH‐Induced Reversible Dynamic Responsive Behaviors

AbstractPoly(acrylic acid‐co‐N‐vinylcaprolactam) (PAN) hydrogels containing multiple hydrogen bonds can exhibit pH‐induced reversible dynamic responsive behaviors. When placing a transparent hydrogel in an acid bath, as hydrogen bonds between comonomer units involving protonated COOH groups are formed faster than water diffusion, a nonequilibrium light‐scattering state is formed to turn the hydrogel opaque, while as the swelling equilibrium is reached over time, the hydrogel regains its transparency. Likewise, when the transparent, hydrogen‐bonded hydrogel is subsequently immersed in DI water, faster water absorption occurs in where more COOH groups are deprotonated, which also generates a light‐scattering state leading to opacity, while the transparency is slowly recovered after equilibrium. Using such two‐way dynamic transparency evolution, a PAN‐based hydrogel material is prepared to demonstrate a dynamic memory system for information memorizing‐forgetting and recalling‐forgetting.

Electrochemical Corrosion Behavior of Passivated Precipitation Hardening Stainless Steels for Aerospace Applications

Precipitation-hardening (PH) stainless steels (SS) are widely used in various aerospace applications. These steels exhibit good mechanical and corrosion resistance. The electrochemical behavior of 15-5PH, 17-4PH, Custom450 and AM 350 stainless steels passivated with citric and nitric acid baths for 60 and 90 min at 25 and 49 °C were evaluated in 5 wt.% sodium chloride (NaCl) and 1 wt.% sulfuric acid (H2SO4) solutions. The electrochemical behavior was studied with potentiodynamic polarization curves (PPC) according to the ASTM G5-13 standard. The results indicated that there are two characteristic mechanisms that are present in the potentiodynamic polarization curves. When the PHSS is immersed in an H2SO4 solution, there is a secondary passivation, and in the NaCl solution, there is a pseudo-passivation (not stable passivation film). The current densities in the NaCl solution were between 10−4 and 10−5 mA/cm2, while those of H2SO4 were recorded around 10−2 and 10−3 mA/cm2. Citric acid does work as a passivating solution, and in some cases, the corrosion resistance of the stainless steel was comparable to that of nitric acid.

ENGINEERING A TENDON-BONE ENTHESIS-MIMICKING HYBRID MATRIX FOR REPAIR OF IRREPARABLE ROTATOR CUFF TEARS

Rotator cuff tears are common, with failure rates of up to 94% for large and massive tears1. For such tears, reattachment of the musculotendinous unit back to bone is problematic, and any possible tendon-bone repair heals through scar tissue rather than the specially adapted native enthesis. We aim to develop and characterise a novel soft-hard tissue connector device, specific to repairing/bridging the tendon-bone injury in significant rotator cuff tears, employing decellularised animal bone partially demineralised at one end for soft tissue continuation.Optimisation samples of 15×10×5mm3, trialled as separate cancellous and cortical bone samples, were cut from porcine femoral condyles and shafts, respectively. Samples underwent 1-week progressive stepwise decellularisation and a partial demineralisation process of half wax embedding and acid bathing. Characterisations were performed histologically for the presence/absence of cellular staining in both peripheral and central tissue areas (n=3 for each cortical/cancellous, test/PBS control and peripheral/central group), and with BioDent reference point indentation (RPI) for pre- and post-processing mechanical properties.Histology revealed absent cellular staining in peripheral and central cancellous samples, whilst reduced in cortical samples compared to controls. Cancellous samples decreased in wet mass after decellularisation by 45.3% (p<0.001). RPI measurements associated with toughness (total indentation depth, indentation depth increase) and elasticity (1st cycle unloading slope) showed no consistent changes after decellularisation. X-rays confirmed half wax embedding provided predictable control of the mineralised-demineralised interface position.Initial optimisation trials show proof-of-concept of a soft-hard hybrid scaffold as an immune compatible xenograft for irreparable rotator cuff tears. Decellularisation did not appreciably affect mechanical properties, and further biological, structural and chemical characterisations are underway to assess validity before in vivo animal trials and potential clinical translation.

Microhardness and tensile strength of electrochemically synthesized nickel-cobalt binary alloy sheets exfoliated from a dumbbell-shaped titanium cathode

Nanocrystalline nickel–cobalt (Ni–Co) binary alloy sheets were fabricated through electroforming in an acidic aqueous bath using exfoliation from a metallic titanium cathode. Cobalt content in Ni–Co alloy sheets ranged from 28.8 at% to 72.0 at% depending on experimental parameters, such as cathodic overpotential and bath composition. The surface roughness (R a) of the electroformed alloy sheets significantly decreased down to 1.5 μm as saccharin sodium dihydrate was added as an additive to the acidic aqueous solution bath. X-ray diffraction profiles and transmission electron microscopy images indicated that the electroformed Ni–Co alloy sheets have a nanocrystalline structure (grain size ≈ 30 nm). The lattice constant of the electroformed Ni–Co alloy sheets increased with an increase in cobalt content (i.e. solute atom concentration). The mechanical properties were significantly improved because of the synergistic effects of crystal grain refinement and solid solution strengthening. The microhardness and tensile strength of the electroformed Ni–Co alloy sheets reached 609 kgf mm−2 and 1757 MPa (X Co = 49.9 at%), respectively. The tensile strength of the electroformed Ni–Co alloy sheets in this study significantly exceeded that of solidified Ni–Co alloys (approximately 370 MPa). Therefore, this study offers a technique to enhance the mechanical properties of electroformed Ni–Co alloy sheets.

Effect of Microcracks Formed in Zn-Ni Alloy Plating Films on Hydrogen Embrittlement of High Strength Steel

Zn-Ni alloy plating from sulfuric acid baths has excellent hydrogen embrittlement resistance for high strength steels. In this study, we investigated the factors that contribute to the hydrogen embrittlement resistance of Zn-Ni alloy plating. In Zn-Ni alloy plating, microcracks are formed in the coating. Hydrogen embrittlement was accelerated by mechanical sealing of these microcracks, and the microcracks that form in the coating were a pathway for hydrogen release. Therefore, these microcracks are found to play an extremely important role in suppressing hydrogen embrittlement. It is suggested that a gap in the plating film that can release hydrogen-induced vacancies is important to suppress hydrogen embrittlement due to plating.