Corrosion Mitigation Research Articles

Spearmint Extract as a Sustainable Corrosion Inhibitor Through Advanced Spray Coating Applications

In this research, the high efficacy of Mentha spicata L. extract, commonly known as spearmint, as a corrosion inhibitor with an efficacy rate of 86.98% is highlighted. Analytical techniques, such as scanning electron microscopy (SEM) to obtain a detailed morphological view, Fourier transform infrared spectroscopy (FTIR) to identify the functional groups of flavonoids, and electrochemical impedance spectroscopy (EIS) and Tafel plots for a corrosion assessment, were employed. This study pioneers a greener alternative to traditional corrosion inhibition methods. The distinctive aspect of this research is the innovative spray coating application method used to deliver the spearmint extract onto structural steel. This method involves the strategic use of an airbrush for spray coating, ensuring the uniform and efficient deposition of the organic inhibitor, thus forming a protective barrier against corrosion. This spray coating technique is emerging as an innovative approach for the industrial application of natural corrosion inhibitors, demonstrating significant advances in the corrosion resistance of coated steel. The results not only corroborate the efficacy of natural inhibitors, but also highlight the critical role that sophisticated application techniques play in improving their industrial viability. This methodological innovation presents a pathway to sustainable practices in corrosion management, prioritizing environmental protection and ecological footprint reduction in the quest for corrosion mitigation.

Copper corrosion mechanisms, influencing factors, and mitigation strategies for water circuits of heat exchangers: critical review and current advances

Abstract This review examines copper corrosion mechanisms and their key influencing factors, including microstructure effects, surface treatments, manufacturing conditions, temperature, water chemistry parameters, fluid velocity, and microbial effects in water-based systems, with a particular focus on heat exchangers. This addresses a critical gap in the existing literature, which often examines copper corrosion in a broader context. By critically analyzing the literature, the review provides an in-depth understanding of the factors that govern copper corrosion in heat exchanger applications. Copper corrosion in heat exchangers can have significant technical and social detrimental consequences, leading to substantial economic losses. By focusing on heat exchangers, the review offers valuable insights and best practices for engineers, researchers, and practitioners working with copper in this domain. Furthermore, the review evaluates the latest mitigation strategies, including advancements in material selection, surface treatments, water treatment techniques, and robust monitoring/maintenance methods. Finally, the review explores promising new concepts for corrosion prevention for long-term performance, paving the way for future research in developing innovative technologies and refining highly effective strategies under diverse operating conditions relevant to combat deleterious copper corrosion effects in heat exchanger applications.

Amorphous Carbon Film as a Corrosion Mitigation Strategy for Stainless Steel in Molten Carbonate Salts for Thermal Energy Storage Applications.

Ternary carbonate salts (Li2CO3-Na2CO3-K2CO3) are promising heat transfer fluids to increase the efficiency of the electric power in concentrated solar power (CSP) technology. However, the corrosion produced at high operating temperatures is a key challenge to tackle for employing cost-effective steels as construction materials in CSP. In this work, the use of stainless steels with amorphous carbon was investigated, for the first time, as a surface modification method to mitigate the corrosion of structural CSP materials by molten salts. In doing so, an amorphous carbon (a-C) film of 100 nm in thickness was deposited on the 301LN stainless steel's surface by the carbon thread evaporation technique. The corrosion behavior of the 301LN was assessed in carbonate salt at 600 °C for 1000 h. This film decomposed forming carbide layers, contributing to corrosion mitigation due to the generation of denser oxide layers, decreasing the Li+ diffusion through the stainless steel.

Effects of Different Inhibitors on the Corrosion Mitigation of Steel Rebar Immersed in NaCl-Contaminated Concrete Pore Solution

The corrosion of steel rebar embedded in concrete under marine conditions is a major global concern. Therefore, it needs a proper corrosion mitigation method. Various types of corrosion inhibitors are used to mitigate the corrosion of steel rebar in chloride-contaminated concrete; however, selecting the appropriate inhibitor and determining its optimal concentration remains a concern. Therefore, in the present study, three types of inhibitors—calcium nitrite (CN: Ca(NO2)2), N,N′-dimethyl ethanol amine (DMEA: (CH3)2NCH2CH2OH), and L-arginine (LA: C6H14N4O2) in three different concentrations, i.e., 0.3, 0.6 and 1.2 M—were compared with a control (without inhibitor, i.e., blank) sample to determine the optimum concentration of the inhibitor for corrosion resistance performance evaluation of reinforcement bars immersed in 0.3 M NaCl-contaminated concrete pore (NCCP) solution for various durations. The corrosion resistance properties were assessed using open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) with immersion duration, and potentiodynamic polarization (PDP) after 168 h of exposure. The results showed that the CN inhibitor performed exceptionally well (corrosion inhibition efficiency greater than 97%) in terms of corrosion resistance. However, due to its hazardous nature and its ban in the U.S. and European Union, CN cannot be used in construction. In comparison, while DMEA showed some effectiveness, LA performed better and is also eco-friendly. The corrosion resistance efficiency of samples containing 0.6 M LA remains above 97% even after 168 h of immersion in the NCCP solution. This efficiency is consistent throughout the entire immersion period, from 1 h to 168 h. Therefore, it is recommended that LA be used as a corrosion inhibitor for steel reinforcement bars instead of CN, particularly in chloride-contaminated concrete, as it is both effective and safer than CN.

ENHANCING SURFACE CHARACTERISTICS OF AA2024-T3 AIRCRAFT ALLOY THROUGH SYNERGISTIC ANODIZATION AND CERIUM CONVERSION COATING. PART I: PERFORMANCE IN MODEL CORROSIVE MEDIUM

The present study is devoted to the monitoring of the performance of AA2024-T3 specimens, after the formation of Anodic Aluminum Oxide (AAO) layer and/or deposition of a Ceruim Conversion Coating (CeCC), obtained at 20°C and 50°C, respectively. Although both methods are well described in the literature, there is no sufficient information regarding the effect of their combination on their behaviour in corrosive media. The performance of the respective specimens was elucidated after 24 h of exposure to 3.5 % NaCl model corrosive medium (MCM) by means of Electrochemical Impedance Spectroscopy (EIS) and acquisition of Potentiodynamic Scanning (PDS) curves. Since the combined AAO/CeCC coating primers revealed superior barrier properties, the respective specimens weresubjected to long-term corrosion tests of up to 672 h of exposure to the MCM to evaluate their durability. The results revealed the synergistic effect of the combination of the surface treatment procedures on effective corrosion mitigation.

Experimental Assessment of Corrosion Properties for Materials Intended for Heavy Crude Processing.

Heavy crude oil processing presents significant challenges owing to its complex composition and requirement for processing conditions, which increase the process safety risk in crude processing units, such as fixed equipment, for instance pressure vessels and pipes. The aim of this work is to evaluate the influence of heavy crude oils named A and B and the effect of sulfur-rich compounds and organic acids on the performance at high temperatures of three metallic alloys (5Cr-1/2Mo/ASTM A335GP5, X6CrNiMoTi17122/AISI-SAE 316Ti and Ni66.5Cu31.5/Monel 400) and propose an alternative to be used in pressure vessels and piping in refineries. This work was based on the need to understand the corrosivity of two heavy crude oils (A and B) from eastern Colombia in three materials, evaluated at three temperatures (200 °C, 250 °C and 300 °C) under the same conditions of pressure (200 psi) and rotation velocity (600 rpm) in a dynamic autoclave to simulate atmospheric conditions and conditions in vacuum refinery towers. An understanding of how these factors interact with the fundamental principles of corrosion kinetics is essential for developing an effective corrosion mitigation strategy. The results were interesting for applications requiring high corrosion resistance. X6CrNiMoTi17122/AISI-SAE 316Ti is a solid candidate for this application, with corrosion rates of 0.2 to 0.87 mpy. Ni66.5Cu31.5/Monel 400 exhibited significant corrosion rates up to 74.89 mpy, especially at higher temperatures (300 °C). 5Cr-1/2Mo/ASTM A335GP5 showed a generally moderate corrosion rate (2.04-5.57 mpy) in the evaluated temperature range.

N, S-Codoped Carbon Quantum Dots with High Inhibition Efficiency: Implications for Corrosion Mitigation of Carbon Steel in Acidic Environments.

The environmental friendliness, economic feasibility, and high efficiency of carbon quantum dots (CQDs) render them as highly promising candidates for corrosion inhibitors. The present study proposed the fabrication of nitrogen- and sulfur-codoped CQDs via an one-step hydrothermal method using l-cysteine and 4-aminosalicylic acid as precursors. The structure, particle size, and surface ligands of the prepared CQDs were determined through spectroscopy and transmission electron microscopy characterization. Subsequently, the inhibition performance of the CQDs on carbon steel in a 0.5 M sulfuric acid solution was evaluated through weight loss measurement, electrochemical methods, and surface analysis. The CQDs exhibited remarkable inhibition efficiencies of 97.9% at 293 K and 98.9% at 313 K, with a concentration of 150 ppm. In addition, the obtained CQDs demonstrated a combined physisorption and chemisorption adsorption behavior, which complied with the Langmuir adsorption isotherm. These findings provide insight into the inhibition mechanism and highlight the potential of codoped CQDs for corrosion mitigation applications in acidic environments.

Synthesis of Schiff bases of 4-methoxybenzyl amine and hydrazide derivatives and their application in corrosion inhibition of mild steel in 1.0 M HCl

In this work, Schiff bases of 4-methoxybenzyl amine and hydrazide derivatives containing succinic (BMSHE), oxalyl (BMOHE), and phenylaceto (BMPHE) have been synthesized and applied for corrosion inhibition of mild steel (MS) in 1.0 M HCl. The synthesized compounds are characterized by Fourier-transform infrared (FTIR) and H1 nuclear magnetic resonance (NMR) spectroscopy. The FTIR and H1 NMR results have confirmed their formation through the presence of functional groups and hydrogen associated with them. Corrosion mitigation examination is done by polarization measurements (PM), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) equipped with energy dispersive X-rays (EDX), and atomic force microscopy (AFM). All inhibitors demonstrated notable efficacy in preventing MS in HCl (BMSHE-88%, BMOHE-84%, and BMPHE-72%). As per corrosion potentials, BMOHE and BMPHE have been found to be mixed types of inhibitors, and BMSHE is noticed as a cathodic inhibitor. The SEM results demonstrated how these hydrazide derivatives prevented corrosion by covering the MS surface. The EDX analysis of the surfaces has revealed that the inhibited MS contains lower amounts of O and Cl, which indicate that the inhibitors prevent MS in HCl. AFM analysis shows that the surfaces of MS in the presence of the inhibitors are damaged less than in their absence, which reveals the same facts as told above. The inhibition of MS by BMSHE, BMOHE, and BMPHE is also explained with a reason after analyzing the results.

Understanding the Effect of Corrosion Resistance in Welded AA2198‐T8 Alloy: Microstructural‐Electrochemical Insights

ABSTRACTIn this study, we explore the corrosion resistance of AA2198‐T8 alloy in friction stir‐welded zones, focusing on microstructure changes and resulting corrosion susceptibility. Macrogalvanic coupling effects are observed in weldment under corrosive conditions, particularly in the welding joint (WJ), heat‐affected zones, and base metal (BM). Severe localized corrosion is prevalent in anodic zones, revealing intricate trenching patterns around micrometric particles in cathodic domains. Investigating isolated zones exposes SLC across all welding‐affected regions and BM, underscoring the involvement of microgalvanic cells in corrosion. The novel utilization of a syringe cell as an electrochemical tool proves to be instrumental in delineating the electrochemical characteristics of welding testing zones. Notably, stir zone within WJ emerges as the region depicting the lowest corrosion resistance, a critical finding substantiated by localized electrochemical impedance spectroscopy. These insights into the interplay of electrochemical phenomena and microstructural attributes have implications for advancing corrosion mitigation strategies and alloy engineering in materials science.

Synergistic inhibition effect of diolefinic dye and silver nanoparticles for carbon steel corrosion in hydrochloric acid solution

The current work looks at the inhibitory effects of a diolefinic dye, namely 1,4-bis((E)-2-(3-methyl-2,3-dihydrobenzo[d]thiazol-2-yl) vinyl) benzene iodide salt, in relation to CS corrosion mitigation in hydrochloric acid (HCl) environment. This study uses a variety of experimental methodologies, including weight loss (WL) analysis, electrochemical tests, and theoretical considerations. The synergistic effect of diolefinic dye and AgNPs on the corrosion inhibition of CS in 1 M HCl was investigated. The inhibition efficiency (IE) displays a notable enhancement as the concentration of the dye is elevated and as the temperature raises the IE increases. The diolefinic dye exhibited % IE of 83% even at low concentration (1 × 10–4 M) whereas 90% in the presence of (2.26 × 10–10) AgNPs. Tafel graphs demonstrate that the dye follows a mixed type inhibitor. The adsorption of the dye on CS surface follows Langmuir model. Moreover, the influence of temperature and the activation parameters disclose that diolefinic dye is chemisorbed on the CS surface. The synergistic coefficient of the diolefinic dye and AgNPs under various concentration conditions was greater than unity. The surface morphology of CS sheets was confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Density Functional Theory (DFT) calculations provide theoretical support for the inhibitory effects of the examined dye. Notably, there is a high agreement between the findings of practical studies and theoretical expectations.

Corrosion mitigation of carbon steel in sulfuric and hydrochloric acid solutions by Syzygium polyanthum (Wight) Walp. leaf extract

It is widely recognized that corrosion has been a persistent issue throughout human history. Over time, various effective strategies have been suggested and successfully employed to combat this problem. Among them, the utilization of inhibitors stands out as a promising, versatile, and easily applicable method. Considering the drawbacks associated with previous substances such as environmental concerns and high operational expenses, plant extracts have emerged as an effective alternative. In there, Syzygium polyanthum (Wight) Walp. stands out as a popular species characterized by a high concentration of polar compounds that is crucial for the formation of a protective film layer on carbon steel. Consequently, this work centers on investigating the corrosion inhibition behavior of Syzygium polyanthum (Wight) Walp. leaf water-extract (SPWE) for carbon steel in different solutions, including 1.0 M HCl, 0.5 M H2SO4, and co-volume acidic mixture, by employing electrochemical and surface techniques. The findings reveal that 2000 ppm of SPWE proved inhibition efficiency exceeding 94.24, 66.27, and 95.02% (estimated by Tafel extrapolation) for carbon steel in 1.0 M HCl, 0.5 M H2SO4, and acidic mixture solutions, respectively. High inhibition performance was also ensured by high polarization resistances (Rp) observed on electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR). Increasing corrosion resistance could be due to the protective layer formed on the inhibited samples, while severe corrosion occurred on the uninhibited steel due to extensive damage across the entire surface. Hence, the study underscores the noteworthy impact of chloride and sulfate ions on corrosive inhibition process of SPWE.

Corrosion mitigation potential of N-(2-(2-pentadecyl-2,5-dihydro-1H-imidazol-1-yl)ethyl)palmitamide palmitate on Q235 steel in sulfuric acid: experimental and theoretical analysis

Corrosion mitigation potential of N-(2-(2-pentadecyl-2,5-dihydro-1H-imidazol-1-yl)ethyl)palmitamide palmitate on Q235 steel in sulfuric acid: experimental and theoretical analysis

Optimizing biosurfactant structure: Experimental and theoretical investigation of the influence of hydroxyl groups on sour corrosion mitigation

Oil and natural gas remain crucial for meeting global energy demands, but their extraction and processing face significant challenges due to sour corrosion. This study explores the influence of hydroxyl groups on the performance of biosurfactants, specifically sorbitol oleate (SOCI) and pentaerythritol oleate (POCI), in sour environments. This study reveals that the presence of more hydroxyl groups in inhibitor molecules significantly enhances their effectiveness against sour corrosion. A weight loss study showed that the corrosion rates dropped to 0.033 mm y−1 for POCI and 0.005 mm y−1 for SOCI from an initial rate of 0.490 mm y−1 in the blank solution, indicating the superior inhibition efficiency of SOCI (98.9%) compared to POCI (93.3%) at 24 × 10−4 M. Electrochemical measurements corroborated these findings, demonstrating increased corrosion resistance and reduced current densities in the presence of both inhibitors, with SOCI exhibiting better performance. The inhibition mechanism involves a combination of physical and chemical adsorption. Density functional theory calculations indicated the role of hydroxyl groups in enhancing adsorption and corrosion inhibition efficiency, with SOCI exhibiting a smaller energy gap, lower hardness, and higher softness compared to POCI. MD simulations confirmed the stable adsorption of both inhibitors on the Fe (110) surface, with SOCI showing a more favorable orientation and stronger interaction due to its higher number of hydroxyl groups. This facilitates stronger adsorption on the CS surface and the formation of a more robust protective film. The combined experimental and computational findings highlight the importance of molecular structure, film-forming ability, and hydroxyl content for the design and development of next-generation hydroxyl-rich biosurfactants for mitigating sour corrosion in the oil and gas industry.

Do Wettability Measurements Define Corrosion Inhibition of Etched Surfaces? A Study on Acid‐Etched 316L Stainless Steel

Special wetting surfaces have attracted attention owing to their potential applications in the automotive, engineering, environmental, and biomedical industries. Specifically, nature‐inspired superhydrophobic surfaces are more effective in blocking moisture, thus limiting corrosion. Hence, surface wettability analysis remains the primary method for demonstrating the corrosion mitigation characteristics of rough‐engineered surfaces. Herein, the influence of wettability measurements on the corrosion inhibition of 316L stainless steel surfaces etched in HCl: HNO3 acid is systematically investigated. Interestingly, etched hydrophobic surfaces with a contact angle of ≈125° significantly improve the corrosion resistance by 50%, resulting in suppressed corrosion rates. Furthermore, the surface chemical states of the etched 316L steel are analyzed and discussed in detail.

Assessment of the inhibition performance of ZIF-8 on corrosion Mitigation of API 5L X65 steel in 3.5 wt% NaCl: Experimental and theoretical insight

The synthesis and application of ZIF-8 as an effective corrosion inhibitor for the corrosion of API 5L X65 steel in 3.5 wt% NaCl have been studied. The synthesized ZIF-8 was characterized using some surface probe approaches, which include field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR TEM), and X-ray photoelectron spectroscopy (XPS), respectively. The results showed that ZIF-8 exhibited regular hexagonal and orthorhombic-shaped nanoparticles. An approximately 62% yield was achieved. Electrochemical studies such as open circuit potential (OCP), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) were performed. The polarization results show that ZIF-8 is a mixed-type inhibitor, revealing a strong impact on both the anodic and cathodic polarization current values. The EIS studies reveal an increase in the charge transfer resistance upon the introduction of ZIF-8. The existence of a strong protective film adsorbed on X65 steel was recognized via XPS and FT-IR analysis. The highest inhibition efficiency value of 98.1% was recorded at a concentration of 0.120 wt% ZIF-8. Quantum chemical computations in the framework of DFT and molecular dynamic simulation were used to determine the reaction sites on the inhibitor, and as such, in-depth insight into the reaction mechanism was revealed.

Cellulose acetate fibers as corrosion inhibitor delivery system for carbon steel

This study evaluated the effectiveness of electrospun cellulose acetate fibers (CAFs) containing oleic acid (OA) for corrosion inhibition on carbon steel in chloride-rich environments. By varying the OA content, CAFs of different thicknesses were produced. Potentiodynamic polarization showed that steel coated with OA-containing CAFs had enhanced corrosion resistance, with higher corrosion potential (Ecorr) and lower corrosion current density (icorr). The electrochemical impedance spectroscopy (EIS) results for the dip-coated sample showed an impedance increase of approximately 20× (from 2 to 40 kΩ cm2), and a capacitance reduction from 10−6 to 10−8 F cm−2, compared to the untreated sample. The protective effect remained even after 48 h of exposure. These findings suggest CAFs as effective carriers for delivering OA inhibitors, offering a promising solution for corrosion mitigation in saline environments.

Photo-induced passivation: A new corrosion mitigation strategy for bronze artefacts

The corrosion behaviors of four ternary Cu-Sn-Pb alloys with varying tin contents were investigated to determine the impact of tin content on the photo-induced corrosion of bronze. Photo-induced passivation, which effectively inhibits corrosion, was observed in all the investigated Cu-Sn-Pb alloys, even those with relatively low tin content, and a possible mechanism was proposed. Based on these findings, photo-induced passivation treatment was applied to two types of artificially patinated bronzes, achieving inhibition efficiencies of up to 82 % and 93 %. This method offers a novel corrosion mitigation strategy for bronze artifacts, capable of avoiding contamination of archaeological artifacts by foreign substances.

Mitigation of mild steel corrosion using Schiff base-derived inhibitors in acidic media: An experimental and theoretical study

Corrosion presents a substantial hurdle in the oil and gas industry, and corrosion inhibitors represent an economically viable strategy for control and prevention. As operating conditions in oil and gas extraction become increasingly harsh, factors such as cost, availability, and service temperature significantly influence inhibitor selection. While there is a wealth of literature on organic corrosion inhibitors, many exhibit a notable decrease in effectiveness at elevated temperatures, hindering their industrial application. To address this issue, we synthesized a novel Schiff base derivative, 1-((E)-(4-chlorophenylimino)methyl)naphthalen-2-ol (E4CMN), and investigated its effectiveness in inhibiting corrosion on Q235 immersed in a 1 M HCl. E4CMN adsorbs onto the surface by forming strong π-d interactions with Fe through the delocalized π electrons in its conjugated structure, effectively blocking the attack of corrosive particles towards the metal surface and consequently suppressing metal corrosion. Our study demonstrates that E4CMN exhibits maximum efficiencies of 96.9 % at a concentration of 250 mg L−1. Importantly, E4CMN shows insensitivity to service temperature, maintaining an 84.4 % corrosion inhibition efficiency even when exposed to 75 °C. This work provides novel insights into mechanism of inhibition of mild steel corrosion by Schiff base derivatives in acidic environments and offers valuable considerations for the development and selection of corrosion inhibitors for high-temperature applications.

Multidimensional Hybrid Metal Phosphonate Coordination Networks as Synergistic Anticorrosion Coatings.

In the technologically important field of anticorrosion coatings, it is imperative to form well-defined and characterized films to protect the metal surface from corrosion. Phosphonate-based corrosion mitigation approaches are currently being exploited. Herein, the synergistic action of alkaline-earth metal ions and two carboxy-diphosphonates, PAIBA [N,N-bis(phosphonomethyl)-2-aminoisobutyric acid] and BPMGLY [N,N-bis(phosphonomethyl)glycine], is explored. Also, a family of four novel hybrid metal phosphonate materials is reported, Mg-PAIBA, Ca-PAIBA, Sr-PAIBA, and Sr-Na-PAIBA, whose topological analysis revealed a variety of underlying networks with the 6,10T9, unc, SP 1-periodic net (4,4)(0,2), and unique topologies. The synergistic metal/carboxy-diphosphonate blends were tested for their anticorrosion performance on carbon steel at preselected concentrations (0.1-1.0 mM) and pH values (4.0-6.0). The results showed an enhanced inhibitory performance in the presence of metal cations at higher concentrations. The inhibition of corrosion at pH 5.0 in the presence of BPMGLY, PAIBA, and their combination with Sr2+ was investigated in detail using electrochemical measurements. Enhanced inhibition was achieved with a 1:1 Sr2+/BPMGLY (or PAIBA) binary system. Polarization curves indicated that the system is a "mixed" inhibitor. This study widens the family of carboxyphosphonate coordination polymers, showing their potential as attractive hybrid coatings with anticorrosion performance.

(Invited) Metal Corrosion Mitigation in Fine Geometries during Chemical Mechanical Planarization

In the Si semiconductor industry, aggressive device geometry scaling has given rise to new processing challenges to each new technology nodes over the past 6 decades. When the feature size shrinks to nanometer regime, new phenomenon emerges whereby significant loss in metal vias and lines can be observed after CMP.Findings from our previous studies suggest just a few nanometers of metal loss imposes serious yield loss in sub-5nm technology nodes MOL and BEOL metallization. Post CMP clean process can be responsible for ~ 50% of the metal loss after CMP. The phenomenon was observed with W, Co, and Cu alike. It affects conductors as well as liner/barrier metals, and exhibits strong dependence on pattern density, feature size, and even underlying layer. [1, 2]. Properly formulated slurries and post CMP clean chemicals can modulate the amount of metal loss and partially alleviate the issue.In this study, we continue to assess how post CMP clean chemicals and modified de-ionized water can influence the amount of metal loss for Cu interconnects. As a starter, blanket wafers resembling several different Cu/liner/low-k stacks were evaluated. The were subjected to polish with the same alkaline slurry followed by various alkaline post clean chemicals (Clean 1, pH ~ 10.2; Clean 2, pH 9.8). It was observed on the attached figure that brush clean only process with DIW alone can induce small amount of Cu loss. For wafers with polish and post clean, on a comparison basis, Clean1 resulted in slightly more Cu loss than Clean2. However, when dilute NH4OH solution (pH ~ 9.6) was introduced to replace DIW during brush clean with Clean1, the amount of Cu loss is reduced, on par with that of Clean2. The observation suggests NH4OH-treated DIW can help alleviate part of Cu loss during post CMP clean process. Patterned wafers with various combination of liner stacks will be subjected to clean process with various combinations of chemistries and/or NH4OH-treated DIW. The amount of Cu or liner loss will be characterized.