This work aims to determine the best substrate preparation and conversion coatings that may enhance the anti-corrosive performance of alumina film/stainless steel substrate systems in Ringer’s solution. Boehmite, silica, silica/boehmite, and boehmite/silica conversion coatings were deposited on sanded or sandblasted 304L stainless steel samples, and the best results were further covered with alumina film for a long-time exposure evaluation. The best anti-corrosive performances for each substrate preparation were observed for the sandblasted sample covered with silica/boehmite conversion coating (JSB500) and the sanded sample covered with silica (LS500), which showed the highest global resistance (Rg) values (828 Ω.cm2 and 1837 Ω.cm2, respectively) and the smallest values of global capacitance, Cg (2.19 X 10-6 F.cm-2 and 3.37 X 10-9 F.cm-2, respectively). After covering with the alumina film and evaluating for 216 h in the corrosive medium, it was noted an increase in the Rg values for both systems (JSBA500 and LSBA500), likely due to the presence of a corrosion products layer. The presence of iron oxides in these conversion coatings led to a more stable alumina film. Comparing the selected coating systems, the LSBA500 exhibited an improved performance, reaching an increase of 85% in Rg and a decrease of 94% in Cg. anticorrosive anti filmstainless Ringers Ringer s solution Boehmite silicaboehmite boehmite boehmitesilica L samples longtime long time evaluation JSB500 JSB (JSB500 LS500, LS500 LS , (LS500) (Rg 828 (82 Ωcm2 Ωcm Ω cm2 cm Ω.cm 183 respectively capacitance 2.19 219 2 19 (2.1 106 10 6 10- F.cm2 Fcm2 Fcm F.cm F F.cm- 337 3 37 3.3 109 9 F.cm2, 2, respectively. . 21 medium JSBA500 JSBA (JSBA50 LSBA500, LSBA LSBA500) layer LSBA50 85 94 JSB50 (JSB50 LS50 (LS500 82 (8 18 2.1 1 (2. 33 3. JSBA50 (JSBA5 LSBA5 8 JSB5 (JSB5 LS5 (LS50 ( 2. (2 JSBA5 (JSBA (JSB (LS5 (LS

This study aims to provide clarity on the potential of graphene in real-life coatings applications and can be viewed as guidelines for graphene end users. To illustrate this, examples of different industrial applications are presented, where graphene-based additives demonstrate a significant impact on corrosion resistance. Furthermore, the underlying mechanisms behind these new products are elucidated. reallife real life users this presented graphenebased based resistance Furthermore elucidated

ABSTRACT Developing high-performing bio adhesives for enhancing the bonding strength of cement-based materials is highly desirable as they improve workability, corrosion resistance and durability of the concrete. The present effort aims at stemming a novel bio admixture comprising agricultural products Cassava starch and Xanthan gum as well examines the effect of incorporation of it into the cement. The composition of xanthan gum is varied in the starch mixture systematically in the ratios namely 1:0.25, 1:0.5 and 1:0.75. As-prepared bio admixtures are characterized through Fourier Transform Infra-Red spectroscopy, X-Ray Diffraction, Thermo Gravimetric Analysis, contact angle and Scanning Electron Microscopy-Energy Dispersive X-ray studies. These results demonstrated that presence of optimal amount of xanthan gum facilitates the binding nature of starch and promotes better bond strength as it significantly improved the bonding capacity as well as hydrophilic nature of starch thereby augmenting the bonding strength when used in cement mortar. The bio admixture filler material occupied the voids between the mortar matrix, thus reducing the porosity. The beneficial effect of as-prepared bio admixture has been reflected in the compressive strength that has been enhanced by 16.6% when optimized quantity (1.5 wt.%) of the bio admixture is added to the mortar. highperforming high performing cementbased based workability concrete 10.25, 1025 1 0.25, 0 25 1:0.25 10.5 105 0.5 5 1:0. 10.75. 1075 0.75. 75 1:0.75 Asprepared As prepared InfraRed Infra Red spectroscopy XRay X Ray Diffraction Analysis MicroscopyEnergy Microscopy Energy Xray ray studies matrix porosity asprepared 166 16 6 16.6 1.5 15 (1. wt.% wt 10 10.25 102 025 0.25 2 1:0.2 10. 05 0. 1:0 10.75 107 075 0.75 7 1:0.7 16. 1. (1 wt. 10.2 02 0.2 1: 10.7 07 0.7 (

ABSTRACT The wide adoption of galvanized steel in the industrial segment, such as the automotive industry, is based on excellent properties in providing durability and weight reduction to manufactured products, in addition to reducing environmental impacts and costs in the production chain, avoiding corrosion, and providing longer lifecycle useful due to the protective zinc layer. However, this layer when submitted to the welding process implies potential defects due to evaporation of zinc vapor and fragility of the liquid metal during welding, with potential generation of porosity, lack of penetration or melting. Ultimately, these defects can significantly impact the reduction of mechanical properties, cracks, and fractures in welded joints. In this work these implications are analyzed through the microstructural characteristics of joints welded with ZAR230 galvanized steel by the GMAW and FCAW welding processes, evaluating the mostly common factors that are modified on an industrial scale in this welding technique: the type of filler metal, whether solid wire or tubular – self-protected with gas protection and without gas protection, and the type of protection gas (with mixtures of 92% Ar + 8% CO2, 80% Ar + 20% CO2 and 95% Ar + 5% O2). Using scanning optical microscopy techniques, metallography, tensile tests and microhardness, the results indicate that all tested conditions have acceptable mechanical properties of hardness and traction, with variation in the presence of defects, inclusions and welding bead, with the best combination being the use of solid wire with mixture 92% Ar + 8% CO2. segment industry products chain corrosion However porosity melting Ultimately cracks ZAR ZAR23 processes technique selfprotected self protected 92 8 CO 80 20 95 5 O2. O2 O . O2) techniques metallography microhardness traction bead ZAR2 9 2

RESUMO A ampla adoção de aço galvanizado no segmento industrial, como a indústria automotiva, baseia-se em ótimas propriedades em conferir durabilidade aos produtos manufaturados, além de reduzir impactos ambientais e custos na cadeia produtiva, evitando-se corrosão e conferindo maior vida útil devido a camada protetora de zinco. Porém, essa camada quando submetida a processo de soldagem implica potenciais defeitos devido à evaporação de vapor de zinco e fragilidade do metal líquido durante a soldagem, com potencial geração de porosidade, falta de penetração ou fusão. Em última instância, esses defeitos podem trazer impactos significativos na redução de propriedades mecânicas, trincas e fraturas nas juntas soldadas. Neste trabalho, essas implicações são analisadas através das características microestruturais e propriedades mecânicas de juntas soldadas com aço galvanizado ZAR230 pelos processos de soldagem GMAW e FCAW, avaliando-se fatores mais amplamente modificados em escala industrial nessa técnica de soldagem: o tipo de metal de adição, sendo ele arame sólido ou tubulares – autoprotegido com proteção gasosa e sem proteção gasosa, e o tipo de gás de proteção (com misturas de 92% Ar + 8% CO2, e 95% Ar + 5% O2). Utilizando-se de técnicas de microscopia ótica de varredura, metalografia, ensaios de tração e microdureza, os resultados apontam que todas as condições testadas possuem propriedades mecânicas de dureza e tração aceitáveis, com variação de presença de defeitos, inclusões e aspecto de cordão, sendo a melhor combinação a de uso do arame sólido com mistura 92% Ar + 8% CO2. automotiva baseiase baseia se manufaturados produtiva evitandose evitando Porém porosidade fusão instância trabalho ZAR ZAR23 FCAW avaliandose avaliando adição 92 8 CO2 CO 95 5 O2. O2 O . O2) Utilizandose Utilizando varredura metalografia microdureza aceitáveis cordão ZAR2 9

ABSTRACT To address the issue of corrosive wear resulting from the addition of desulphurization wastewater into the wet slag removal system, this study investigated the corrosive wear behavior of chain steel (specifically 17NiCrMo6 steel) in desulphurization wastewater with varying chloride concentrations. Weight loss, micro-phase characterization, and electrochemical testing methods were employed for analysis. The findings indicate that as the chloride concentration increases, the weight loss rates for both pure corrosion and corrosive wear exhibit a pattern of initial increase, followed by a decrease, and then another increase. This trend can be attributed to the fact that as the chloride concentration rises, the corrosion products become denser, thereby increasing the difficulty of the corrosion reaction. system specifically NiCrMo 17NiCrMo concentrations microphase micro phase characterization analysis increases increase decrease rises denser reaction

RESUMO A compreensão dos fenômenos envolvidos na corrosão do aço carbono em meio H2SO4 é de fundamental importância, visto que este é o principal produto da indústria química. Contudo, poucos trabalhos recentes relacionados a corrosão do aço carbono em H2SO4 em diferentes concentrações de sulfato são reportados. O presente trabalho objetivou estudar a corrosão do aço carbono em H2SO4 1 mol L–1 sob incremento de íons SO42– de origem salina. Medidas de potencial a circuito aberto, ensaios de imersão com perda de massa, quantificação do teor de íons ferro total em solução e curvas de polarização potenciodinâmica foram realizadas e sugerem que a corrosão do aço carbono em H2SO4 com adição de sulfato ocorre por mecanismo de dissolução-passivação, sendo influenciada pela concentração de sulfato adicionado. Micrografias da superfície do aço carbono denotam que a corrosão ocorre de maneira uniforme e com a formação de produtos de corrosão insolúveis distribuídos não homogeneamente na superfície metálica. Tais produtos estão provavelmente associados à precipitação de FeSO4 e/ou Fe(OH)3 na superfície. HSO H SO H2SO importância química Contudo reportados L1 L L– SO42 salina aberto massa dissoluçãopassivação, dissoluçãopassivação dissolução passivação, passivação dissolução-passivação adicionado metálica FeSO eou ou FeOH3 FeOH Fe OH 3 Fe(OH) SO4 Fe(OH

ABSTRACT Understanding the phenomena involved in the corrosion of mild steel in H2SO4 media is of fundamental importance as it is a principal product of the chemical industry. However, a few recent studies have reported the corrosion of mild steel in H2SO4 at different sulfate concentrations. This study aims to investigate the corrosion of mild steel in 1 mol L–1 H2SO4 with the addition of sulfate ions from saline sources. Open-circuit potential measurements, immersion tests with mass loss, quantification of total iron ion content in solution, and potentiodynamic polarization curves were conducted. This suggests that the corrosion of mild steel in H2SO4 with added sulfate occurs via a dissolution-passivation mechanism, which is influenced by the concentration of added sulfate. Micrographs of the mild steel surface indicate that corrosion occurs uniformly with the formation of insoluble corrosion products that are non-homogeneously distributed on the metal surface. These products were likely associated with the precipitation of FeSO4 and/or Fe(OH)3 on the surface. HSO H SO H2SO industry However concentrations L1 L L– sources Opencircuit Open circuit measurements loss solution conducted dissolutionpassivation dissolution passivation mechanism nonhomogeneously non homogeneously FeSO andor or FeOH3 FeOH Fe OH 3 Fe(OH) Fe(OH

Abstract IE(%) of CORP (with AN of 7.8 and 3.5., and modified with Zn powder, MGr or MCNT) used as coatings against CS atmospheric corrosion has been investigated. The studies were carried out by gravimetry and PSP methods. CORP composition was: phosphatides, hydrated oil and SF. IE(%) effect of CO coatings with the investigated compositions on CS corrosion kinetic parameters was estimated in a 0.5 M NaCl solution. Zn powder (50 wt.%) addition to CORP increased their IE(%) up to 80-86%. In this case, the coatings IE(%), at an anodic E of -0.2 V, reached 93-99%. The addition of MGr or MCNT to CORP modified by Zn powder had mostly a negative effect on IE(%).

Abstract Tuxpan is a port with economic and industrial important activity subject to atmospheric corrosion of metal structures such as boats, ships, oil platforms, and power stations. The main purpose of this paper is to evaluate the atmospheric corrosion of Tuxpan Veracruz, it was necessary to install an exposition panel with carbon steel specimens, galvanized steel (zinc), and copper to evaluate them in every season by electrochemical methods (electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and potentiodynamic polarization curves (CP). In addition, corrosivity indexes of atmospheric are evaluated by CLIMAT and ISO methodology. An exposition panel was installed with specimens of aluminum wire on steel screws, copper screws, and nylon screws to study corrosivity indexes through mass loss in every season of the year and thus classify the different types of atmospheres; marine, industrial, and rural-urban according to the values specified in the standard (ISO 8408, 9223, 9224). The corrosivity indexes are under the standards allowed in the regulations. However, they show the aggressiveness of the marine and industrial atmosphere due to the location and activities of the port in the northern zone. Zinc and carbon steel corrodes due to aggressive agents such as chlorides and sulfur dioxide, forming soluble oxides on the surface of the metallic substrate, while copper forms corrosion products that weakly protect its surface.

Resumen Tuxpan es un puerto con importante actividad económica e industrial, ha sido objeto del proceso de corrosión atmosférica en las estructuras metálicas como embarcaciones, botes, plataformas petroleras y Termoeléctricas. El propósito principal de este trabajo es evaluar la corrosión atmosférica de Tuxpan Veracruz, se instaló un panel de exposición con probetas de acero al carbono, acero galvanizado (zinc) y cobre para poder evaluarlas en cada estación del año por métodos electroquímicos (impedancia electroquímica espectroscopia (EIE), resistencia de polarización lineal (Rp) y curvas de polarización potenciodinámicas (CP). Además, se evalúan los índices de corrosividad de la atmósfera mediante la metodología CLIMAT e ISO. Se instaló un panel de exposición con probetas de alambre de aluminio sobre tornillos de acero, tornillos de cobre y tornillos de plástico para estudiar los índices de corrosividad por pérdida de masa en cada estación del año, y así clasificar los diferentes tipos de atmósferas: marina, industrial y rural-urbana según los valores especificados en la norma (ISO 8408, 9223, 9224). Los índices se encuentran por debajo de los estándares permitidos en la normatividad. Sin embargo, muestran la agresividad del ambiente marino e industrial producto de la ubicación y actividades del puerto en la zona norte. El zinc y el acero al carbono se corroen debido a agentes agresivos como los cloruros y el dióxido de azufre, formando óxidos solubles en la superficie del sustrato metálico, mientras que el cobre forma productos de corrosión que protegen débilmente su superficie.

Abstract U2 and U4 were successfully synthesized from C7H6N2 N-alkylation (general and useful route to quaternary ammonium salts NH4Cl from tertiary amines) with alkyl bromides. The products were further alkylated to the corresponding ILs: U5 and U7. All the synthesized compounds were characterized by spectroscopic techniques, and their compositions were established through elemental analysis. The synthesized compounds were investigated as inhibitors for MS corrosion, using 1 M HCl as a model solution. WL experiments, surface analysis, quantum chemical calculations and MD simulation methods were used for evaluating the inhibitors anticorrosion properties. The results showed that ILs possessed remarkable inhibition properties under the studied conditions. U5 displayed the highest IE of 95.22%, at 200 ppm. ILs corrosion IE(%) was ascribed to their adsorption onto the MS surfaces, which followed the Langmuir’s isotherm. SEM revealed the formation of a barrier film by the inhibitors on the MS surface. Finally, the experimental results were corroborated by theoretical quantum chemical calculations and MD simulation studies. The studied inhibitor molecules interaction energies with the Fe surface followed the order U5 > U7 > U2 > U4, which is consistent with the experimental data.

The low-temperature electrochemical corrosion behavior of aircraft 2024 aluminum alloy was investigated in different concentrations of potassium-acetate-type fluid, and the results showed that the corrosion medium initially impacted some corrosiveness on the 2024 aluminum alloy. However, the corrosion rate of the alloy decreased with prolonged immersion in the corrosion medium, and this was attributed to the protective effect of the corrosion products layer, which impeded the attack by the aggressive solution. Time-domain analysis of electrochemical noise measurements at -5 °C revealed the occurrence of uniform corrosion on the alloy at the initial stages of immersion, general corrosion at the middle stages of immersion, and a pitting-dominated corrosion type from the middle to late stages of immersion. lowtemperature low temperature 202 potassiumacetatetype potassium acetate fluid However layer solution Timedomain Time domain 5 - C pittingdominated pitting dominated 20 2

In this work, the effects of electric pulse treatment on the discharge and electrochemical properties of rolled and extruded AZ61 as anode of Mg-air battery were studied. The microstructure, electrochemical behavior and surface morphology after discharge were discussed to relate the discharge performance. The experimental results show that compared with the original magnesium anode (rolled and extruded), the magnesium anode treated by electric pulse has more negative corrosion potential, lower impedance value, higher discharge voltage and better specific energy. This is because electric pulse treatment can cause the coarse second phase in magnesium anode to dissolve and the grains to become more uniform. In particular, in the discharge process, the surface of magnesium anode after electric pulse treatment will form micro cracks, which is beneficial to promote the self-stripping of discharge products. It is worth noting that the effect of electric pulse treatment on rolled anode is better than that of extruded anode. It may be due to the different dislocation density in the two anodes. During the electric pulse treatment, the dislocation density in the alloy is highly correlated with the dissolution rate of β-Mg17Al12, which ultimately affects the volume fraction of the second phase in the alloy. work AZ AZ6 Mgair Mg air studied microstructure performance extruded, , extruded) potential value energy uniform particular process cracks selfstripping self stripping products anodes βMg17Al12, βMg17Al12 βMgAl β Mg17Al12, Mg17Al12 Al β-Mg17Al12 βMg βMg17Al1 MgAl Mg17Al1 β-Mg17Al1 βMg17Al Mg17Al β-Mg17Al

Ti alloys are widely used in severe corrosion environments where corrosion resistance is required, as biomedical industry. Additive manufacturing produces customized and complexes products. Laser texturing is a process of structuring surfaces using laser pulses, that allows the creation of periodic patterns on the surfaces of materials, to modify them, functionally and/or aesthetically, in a precise and direct way, allowing parameterization, versatility and repeatability. Consequently, bringing together metallic additive manufacturing with laser texturing process could be an alternative to obtain parts with functional hydrophilic surfaces, which improves osteointegration and reduces bacteria adhesion. Thus, the aim of this work is to characterize and evaluate the influence of LASER parameters in as-built additive manufactured potential biomedical components. Ti6Al4V specimens were produced by L-PBF, using Ytterbium LASER with maximum power of 500 W, varying the laser power from 61 W to 244 W. The samples were characterized by SEM, Microhardness, and wettability. After that, some specimens were Laser textured using an Ytterbium optical fiber laser, and then evaluated by SEM, wettability, and 3D roughness. It was possible to observe that the surface of all studied samples was flattened after Laser texturing in comparison with as-built condition, due to the melting of the powder particles. required industry products pulses materials them andor or aesthetically way parameterization repeatability Consequently adhesion Thus asbuilt built components TiAlV Al V LPBF, LPBF L PBF, PBF L-PBF 50 6 24 SEM Microhardness wettability D roughness condition particles 5 2

The aerospace industry is constantly looking for innovative materials that exhibit good mechanical and corrosion properties. The 2198-T851 (Al-Cu-Li) alloy was developed to replace the conventional Al-Cu-Mg in aircraft structures. Despite the usefulness of the 2198-T851 alloy, its performance may be affected when subjected to an aggressive medium containing chloride ions. The deposition of Nb2O5 coatings by using the reactive sputtering technique on the 2198-T851 alloy surface appears as a powerful tool to improve the corrosion resistance of this material. Recently, groundbreaking research findings have demonstrated the positive effect of Nb2O5 coatings on corrosion protection of alloy 2198-T851. However, the corrosion products originated from the 2198-T851 aluminium alloy are poorly understood. The use of Raman spectroscopy and XPS techniques may help to shed some light on the corrosion products of 2198-T851 alloy. Results demonstrated the corrosion products are mainly composed by CuCl2 x H2O, CuCl, Cu2Cl(OH)3, Al(OH)3, and AlO(OH). properties 2198T851 T 2198 T851 2198-T85 AlCuLi Al Cu Li (Al-Cu-Li AlCuMg Mg structures ions NbO Nb O Nb2O material Recently 2198T851. T851. However understood CuCl H2O HO H Cu2ClOH3, Cu2ClOH3 CuClOH Cu2Cl OH 3, 3 Cl Cu2Cl(OH)3 AlOH3, AlOH3 AlOH Al(OH)3 AlOOH. AlOOH AlO . AlO(OH) 2198T85 219 T85 2198-T8 ClOH Cu2ClOH Cu2Cl(OH) Al(OH) AlO(OH 2198T8 21 T8 2198-T Cu2Cl(OH Al(OH 2198T 2

ABSTRACT Studies have already shown that zamac anodizing is an alternative to minimize the corrosive effects of the alloy. Other studies, in aluminum, demonstrated that when anodized and sealed by the hot process, it promotes an increase in its resistance to corrosion. However, there are no reports in the literature about heat sealing in anodized zamac. The objective of this work is to identify the effect of sealing, in terms of corrosion resistance, on anodized zamac. For this purpose, industrially sanded and polished pieces of zamac 5 were anodized in 0.3 M oxalic acid electrolyte at different times (5, 30 and 60 minutes), and subsequently sealed in distilled H2O at 90ºC for one hour. The parts were analyzed using morphological techniques and corrosion tests. The results showed that with increasing anodization time, the bigger crystallites dissolve, originating smaller crystallites until the formation of a smooth layer. In addition, the sealing process promoted hydration of the anodized zamac products. However, with increasing anodizing time, the oxide layer became more compact, due to smaller crystallites, with a decrease in thickness, due to the smooth layer. This resulted in the best anti-corrosive performance of the 5-minute anodized and sealed sample. alloy studies aluminum However purpose 03 0 3 0. 5, (5 6 minutes, minutes , minutes) HO H O ºC hour tests time dissolve addition products compact thickness anticorrosive anti 5minute minute sample (

RESUMO Estudos já demonstraram que a anodização de zamac é uma alternativa para minimizar os efeitos corrosivos da liga. Outros estudos, em alumínio, demonstraram que quando anodizado e selado pelo processo à quente, promove aumento da sua resistência à corrosão. No entanto, não se tem relatos na literatura sobre selagem à quente em zamac anodizado. O objetivo deste trabalho é identificar o efeito da selagem, quanto a resistência de corrosão, sobre zamac anodizado. Para tanto, peças de zamac 5 lixadas e polidas industrialmente foram anodizadas em eletrólito 0,3 M de ácido oxálico em diferentes tempos (5, 30 e 60 minutos), e posteriormente seladas em H2O destilada à 90ºC por uma hora. As peças foram analisadas por técnicas morfológicas e de corrosão. Os resultados mostraram que com o aumento do tempo de anodização os cristalitos maiores dissolvem-se originando cristalitos menores até a formação de camada lisa. Além disso, o processo de selagem promoveu a hidratação dos produtos anodizados do zamac. No entanto, com o aumento do tempo de anodização, a camada de óxido ficou mais compacta, devido aos menores cristalitos, com diminuição da espessura, devido à camada lisa. Isso resultou no melhor desempenho anticorrosivo da amostra anodizada por 5 minutos e selada. liga estudos alumínio corrosão entanto tanto 03 0 3 0, 5, (5 6 minutos, , minutos) HO H ºC hora dissolvemse dissolvem lisa disso compacta espessura selada (

Flow is central to the operation of wells and pipelines and can be postulated to govern the formation of protective corrosion product layers, which is critical to overall infrastructure integrity. However, the phenomena involved remain poorly understood. Therefore, the main objective of this work was to investigate the effect of flow on the heterogeneous precipitation of FeS and FeCO3 as corrosion products on mild steel. Initial corrosion studies were conducted in an autoclave stirred by an impeller. The tests were conducted under quiescent and dynamic conditions for 24 h in an aqueous brine (10 wt.% NaCl, 120°C, 5 bar CO2, 0 and 10-3 mol/l Na2S2O3). The experimental results showed that the increase in rotation speed did not prevent the formation of FeS or FeCO3 crystals. Having confirmed the presence of corrosion product layers, the differences in the trends in corrosion rates may result from the diffusion barrier presented by these layers. layers integrity However understood Therefore FeCO steel impeller 2 10 (1 wt wt. NaCl 120C C 120 120°C CO2 CO 103 3 10- moll mol l Na2S2O3. Na2S2O3 NaSO . Na S O Na2S2O3) crystals 1 ( 12 Na2S2O