Search Results (19)

Under China’s “dual carbon” goals (carbon peaking and carbon neutrality), the utilization of high-chlorine coal faces significant challenges due to its abundant reserves in regions such as Xinjiang and its notable environmental impacts. This study systematically investigates the combustion characteristics, environmental risks, and control strategies for high-chlorine coal. Key findings reveal that chlorine release occurs in three distinct stages, namely low-temperature desorption, medium-temperature organic bond cleavage, and high-temperature inorganic decomposition, with release kinetics governed by coal metamorphism and the reaction atmosphere. Chlorine synergistically enhances mercury oxidation through low-activation-energy pathways but exacerbates boiler corrosion via chloride–sulfate interactions. Advanced control technologies—such as water washing, calcium-based sorbents, and integrated pyrolysis–gasification systems—demonstrate substantial emission reductions. However, challenges remain in addressing high-temperature corrosion and optimizing multi-pollutant synergistic control. This study provides critical insights into the clean utilization of high-chlorine coal, supporting sustainable energy transitions. Full article

The corrosion behaviour of lean duplex S32101 (1.4162—X2CrMnNiN21-5-1) stainless steel was assessed in various corrosive environments relevant to the pulp and paper industry. Electrochemical techniques, including open-circuit potential measurements and cyclic polarisation, were used to evaluate the corrosion resistance of S32101 stainless steel in various acidic, saline, and industrial liquors such as black, green, and white liquors, as well as dissolved chlorine dioxide bleaching solutions. To evaluate the extent of damage and corrosion mechanisms, post-exposure surface analysis was conducted using scanning electron microscopy (SEM). The results showed that S32101 experienced pitting corrosion in chloride-containing solutions, particularly in salt and acidified-salt environments. Corrosion rates increased with rising temperatures across all solutions. The highest corrosion rate of 3.17 mm/yr was observed in the highly alkaline white liquor at 50 °C, whilst chlorine dioxide induced the least aggressive effects at all temperatures. The suitability of S32101 stainless steel in handling pulp and paper liquors is shown in its corrosion resistance against the bleaching medium and low-temperature saline solutions, but it is not recommended for prolonged exposure to high alkaline liquors or chloride-rich solutions. Full article

Marine environment-induced apparatus failures have led to substantial losses in marine engineering. Graphite/copper composites, known for their excellent electrical conductivity and wear resistance, are extensively utilized in various electric contact devices. However, research on the current-carrying friction and wear behavior of graphite/copper composites in marine environments is still limited. This study investigates the effects of mating materials, graphite content (30 wt.% and 45 wt.%), and electric voltage on the friction and wear mechanisms of graphite/copper composites in seawater. The results show that under seawater coupled with electricity, no mass loss was observed in the 30 wt.% graphite composites after friction tests against different counterparts. Electric voltage (3 V) affects the composite’s damage mechanism, inducing delamination wear, arc erosion and accelerating corrosion. Specifically, the electricity factor promotes oxidation recreations while inhibiting chlorine formation. Notably, when the composite is paired with gold-coated copper, it undergoes electrochemical reactions, leading to the formation of needle-like copper oxide. These oxides alter the surface morphology, elevate the mass of worn composites, and raise the friction coefficient of the tribopair to approximately 0.3, an increase from 0.2. Full article

Fusion-welded austenitic stainless steel (ASS) was predominantly employed to manufacture dry storage canisters (DSCs) for the storage applications of spent nuclear fuel (SNF). However, the ASS weld joints are prone to chloride-induced stress corrosion cracking (CISCC), a critical safety issue in the nuclear industry. DSCs were exposed to a chloride-rich environment during storage, creating CISCC precursors. The CISCC failure leads to nuclear radiation leakage. Therefore, there is a critical need to enhance the CISCC resistance of DSC weld joints using promising repair techniques. This review article encapsulates the current state-of-the-art of peening techniques for mitigating the CISCC in DSCs. More specifically, conventional shot peening (CSP), ultrasonic impact peening (UIP), and laser shock peening (LSP) were elucidated with a focus on CISCC mitigation. The underlying mechanism of CISCC mitigation in each process was summarized. Finally, this review provides recent advances in surface modification techniques, repair techniques, and developments in welding techniques for CISCC mitigation in DSCs. Full article

Dechlorination is a crucial strategy for archeological bronze stabilization to resist corrosion induced by cuprous chloride (CuCl). Conventional samples, either archeological or simulated ones, have deficiencies in revealing dechlorination mechanisms for their complex rust layers and difficulties in quantifying chlorine content. In this work, samples with fixed chlorine amounts were prepared by compressing method to solve overcomplicated and unquantifiable problems. Then, patina profiles and desalinization solutions were analyzed to revisit the dechlorination mechanism across varying solution concentrations and current densities after dechlorination treatments. Results indicate that the sodium hydroxide (NaOH) desalinization method is achieved by converting CuCl to trihydroxychloride (Cu₂(OH)₃Cl). However, this transformation leads to an expansion of the CuCl layer, nearly doubling the CuCl layer thickness at the current density of 25 μA/cm². Dechlorination solution measurements provide information on quantifying chlorine removal and dechlorination progress. Theoretically, the endpoint (c₀) for the NaOH dechlorination method is supposed to be a chloride ion concentration of 358.2 ppm. As the NaOH solution concentrations vary from 10⁻⁶ to 10⁻², CuCl dechlorination progress (E_t=24h) calculations are at about 3% to 6% at 24 h. Applying the current significantly improves the effectiveness of dechlorination at 2.5 μA/cm². However, the chloride ion concentration in the solution starts to decrease after reaching a current density of 12.5 μA/cm², even dropping to 12.07 ppm at 25 μA/cm². According to a theoretical analysis, chlorine evolution during electrolytic processes would be responsible for this phenomenon. Full article

High-temperature corrosion within waste incineration boilers leads to the thinning of their four-tube heating surfaces and frequent tube ruptures, posing a formidable challenge to the development of the waste-to-energy sector. This predicament critically constrains the advancement of China’s waste management and environmental protection sectors. This study focuses on elucidating high-temperature corrosion mechanisms and exploring coating protection methodologies relevant to waste boilers. For corrosion mechanisms, the study comprehensively reviews various factors such as the characteristics of high-temperature chlorine-induced corrosion, gaseous- and molten-chloride-induced corrosion, and sulfidation and multiphase-coupled corrosion; the influence of wall temperature on corrosion; and temperature effects on corrosion. Regarding coating protection technologies, this study traces the historical progression of various coating techniques, providing an overview of methods such as supersonic flame spraying, Inconel 625 surfacing, laser cladding, induction melting, thermosetting-reaction nanoceramic coating, and aluminizing. Special emphasis is placed on the mechanisms and principles of the widely adopted surfacing and induction melting techniques. Overall, the study ventures into the prevailing challenges and envisions the future trajectories of high-temperature anticorrosion mechanisms and coating protection technologies for China’s waste boiler sector. Full article

In this study, chlorine-induced corrosion and blister formation on steel pipes (SPs) coated with modified polyethylene powder (MPP) were evaluated through various tests, including chlorine exposure, wet immersion, and temperature gradient experiments. The results confirmed that the extent of corrosion and iron leaching varied with the coating type as expected. In batch leaching tests, no corrosion was observed on modified polyethylene-coated steel pipes (MPCSPs) within a chlorine concentration range of 0 mg/L to 10 mg/L; similarly, there were no significant changes in specimen weight or iron levels. In contrast, the control group with uncoated SPs exhibited significant iron leaching and corrosion, a trend consistent in sequential leaching experiments. SEM analysis after a month of chlorine exposure revealed no significant corrosion on MPCSPs, and SEM-EDX confirmed no major changes in the carbon bond structure, indicating resistance to high chlorine concentrations. Comparative analysis of wet immersion and temperature gradient tests between MPCSP and conventional epoxy-coated SP (ECSP) specimens revealed that MPCSPs did not develop blisters even after 100 days of immersion, whereas ECSPs began showing blisters as early as 50 days. In temperature gradient tests, MPCSPs showed no blisters after 100 days, while ECSPs exhibited severe internal coating layer blisters. Full article

The assumptions of contemporary energy policies are increasing the share of renewable energy sources. Biomass combustion is developing as an alternative to fossil fuels. However, it faces challenges such as limited corrosion resistance of steel boiler components due to chloride compounds in flue gases and fly ash. This paper provides a comprehensive thermodynamic analysis of chloride-induced corrosion in steel in the Fe-O-Cl-Na environment, focusing on the influence of steam concentration in the gas phase. The study was performed by using the general thermodynamic rules, the thermodynamic properties of the pure components involved in the reaction, and the properties of the solutions formed in the liquid and gas phases. The study also examined the impact of alkali metal chlorides, particularly NaCl, on the formation of NaFeO₂ in the passive oxide scale layer Fe₃O₄/Fe₂O₃. Furthermore, it investigated the condensation of NaCl vapour formation of low-melting eutectic mixtures in deposits and the resulting consequences on the corrosion process. The role of HCl in the chlorination and oxidation process of steel in melted ash deposits was also discussed. The presented thermodynamic analysis was compared with assumptions of an “active oxidation” model. This study can be a valuable resource for experimental research planning and a guide for preventing corrosion in industrial settings. Full article

The production of concrete and the manufacturing process of cement result in a significant carbon footprint, contributing to a large portion of global emissions in structures such as buildings, bridges, roads, and tunnels. Although concrete is an ideal building material that is durable and long-lasting, it can be susceptible to micro-cracks. These micro-cracks in concrete can allow water and chlorine ions to penetrate the structure, leading to the degradation of the concrete and corrosion of the reinforcement, posing an unacceptable level of structural risk. Self-healing concrete is not a new material in the construction industry but can be characterized by the capability of concrete to repair its cracks autogenously or autonomously. Recent advancements in concrete research and technology have given us a better understanding of concrete’s healing properties. Self-healing concrete combines durability with sustainability while offsetting the high carbon output of concrete manufacturing and production and associated life-cycle costs. Technologies such as microbially induced calcite (calcium carbonate) precipitation, shape-memory polymers, encapsulation methods, hydration, and swelling agents can potentially reduce carbon emissions while enhancing resilience and longevity. This paper examines these technologies and their applications in the construction industry by comprehensively reviewing the literature and available case studies. This study concluded that there are promising advancements and innovations in concrete, particularly when improving upon its autogenous healing properties. The recommendations for future research include exploring more ways to bring the concrete industry and cement manufacturing toward net-zero carbon emissions. Full article

The use of poultry litter (PL) as a sustainable fuel is gaining more attention due to its wide availability and carbon neutrality. However, this type of feedstock is rich in ash and typically contains a high concentration of chlorine (Cl) and alkali elements (Na, K). Therefore, it is likely to cause unwanted issues during combustion and co-combustion, such as chlorine-induced corrosion, ash deposition, and bed agglomeration. In this study, for the first time, the influence of aluminosilicate additives on the above problems of poultry litter was investigated. Three aluminosilicate minerals are under consideration: kaolin, halloysite, and bentonite. Their influence on the chemical composition and meting tendencies of two poultry litter ashes are determined. The investigated ashes, PL1 and PL2, are characterized by different chlorine contents of 6.38% and 0.42%, respectively. The results show that in the case of the chlorine-rich PL1 ash, the additives reduced the chlorine content by up to 45%, resulting in a 3.93% of chlorine in the case of halloysite, 3.48% in the case of kaolin, and 4.25% in the case of bentonite. The additives also positively influenced the shrinkage starting temperature and the deformation temperature of the PL1 ash. Full article

Chlorine (Cl₂) exposure poses a significant risk to ocular health, with the cornea being particularly susceptible to its corrosive effects. Antioxidants, known for their ability to neutralize reactive oxygen species (ROS) and alleviate oxidative stress, were explored as potential therapeutic agents to counteract chlorine-induced damage. In vitro experiments using human corneal epithelial cells showed decreased cell viability by chlorine-induced ROS production, which was reversed by antioxidant incubation. The mitochondrial membrane potential decreased due to both low and high doses of Cl₂ exposure; however, it was recovered through antioxidants. The wound scratch assay showed that antioxidants mitigated impaired wound healing after Cl₂ exposure. In vivo and ex vivo, after Cl₂ exposure, increased corneal fluorescein staining indicates damaged corneal epithelial and stromal layers of mice cornea. Likewise, Cl₂ exposure in human ex vivo corneas led to corneal injury characterized by epithelial fluorescein staining and epithelial erosion. However, antioxidants protected Cl₂-induced damage. These results highlight the effects of Cl₂ on corneal cells using in vitro, ex vivo, and in vivo models while also underscoring the potential of antioxidants, such as vitamin A, vitamin C, resveratrol, and melatonin, as protective agents against acute chlorine toxicity-induced corneal injury. Further investigation is needed to confirm the antioxidants’ capacity to alleviate oxidative stress and enhance the corneal healing process. Full article

The presented research determined the performance of the protective coatings against the corrosion process under biomass and refuse-derived fuel (RDF) ash deposits. High-temperature corrosion tests were performed on steel grades intended for use in the fabrication of pressure parts working in elevated temperatures such as superheaters in power boilers. Two steel grades were investigated, P235GH and 16Mo3, and two protective coatings were applied, Inconel 625 and Alloy 310. The samples were sourced from the industrial boiler manufacturing company. The samples were exposed to two ashes originating from biofuels and one ash originating from RDF for comparison, all collected from Polish heat plants and power plants. Exposures were carried out in an oxidizing atmosphere for a maximum time of 504 h. The test temperatures of 480, 520, and 580 °C simulated superheater conditions of biofuel- and waste-fired power boilers. The corrosion kinetics were determined by weight change measurements conducted after 24, 168, and 504 h of the exposure. Regardless of the exposure temperature and the type of ash under which the samples were investigated, the use of 2.0 mm thick protective coatings resulted in smaller increases in the weight of the tested coupons which proves that alloy coatings give measurable results and are good remedies for chlorine-induced corrosion. Full article

Detailed tests and characterizations were used to investigate the corrosion degradation behaviors of Ti6Al4V alloys in simulated marine environments. These alloys suffered from very slight pitting and a miniscule weight loss of 0.018 mg/cm² during the 50 cycle salt spray exposure but experienced significant oxygen erosion in the high-temperature oxidation test, resulting in a high weight gain of 2.657 mg/cm² at 400 h. The oxidation and degradation reactions simultaneously occurred during the high-temperature hot salt test. The chlorine (Cl₂) induced by the eutectic reaction of the mixed salts accelerated the degradation of the substrate and led to a higher weight gain of 4.265 mg/cm² at 400 h. In contrast, this alloy suffered from severe corrosion damage during the high-temperature hot salt–water vapor synergy test. The degradation of TiO₂, Al₂O₃, and V₂O₅ was aggravated by the synergistic action of chlorine salt and water. The reaction forming hydrochloric acid (HCl) further degraded the matrix metal and consequently led to a high weight loss of 16.358 mg/cm² at 400 h. These current findings provide a comprehensive understanding for the degradation mechanisms of Ti alloys in these specific marine environments. Full article

As there is a strong pressure in the EU to reduce CO₂ emissions and overall fossil fuel consumption in the energy sector, many boilers are burning biomass instead of traditional fuels (coal, natural gas, oil, etc.). This is mainly due to the EU 2030 energy strategy, which commits Member States to reduce fossil fuel emissions by at least 40% (compared to the 1990 level) and to use at least 32% of renewable energy. The combustion of biomass containing aggressive elements such as chlorine or sulfur causes serious damage to various boiler components, with negative impacts such as reduced boiler lifetime, increased investments and maintenance costs, reduced availability, and others. These problems occur mainly in plants/boilers designed to burn coal and redesigned to burn biomass (straw, wood chips, wood pellets, etc.). In this paper, the corrosion resistance of heat coatings determined in long-term laboratory tests in an environment specifically corresponding to biomass flue gas is presented. These results can be used to design a suitable modification of existing coal boilers using conventional materials. The aim was to compare three completely different technologies currently available on local markets for the preparation of these coatings—thin wire arc spray (TWAS), high-velocity oxygen fuel (HVOF), and water-stabilized plasma. These coatings were compared with the base material of the boiler tubes—low alloyed steel 16Mo3 and high alloyed austenitic stainless steel AISI 310 as a more expensive option for retrofit. After 5000 h of exposure in an environment containing HCl and SO₂, no cracks or structural defects were observed in any of the coatings, and the substrate material showed no signs of oxidation. All the tested coatings had higher corrosion resistance than the 16Mo3 material, and some of them presented a corrosion behavior close to that of the high alloy AISI 310 steel. Structurally and corrosion-wise, the thermally sprayed coating prepared by HVOF technology was the best of all tested materials. Full article

In several industrial processes, metallic materials suffer from chlorine- and sulfur-induced high-temperature corrosion. In previous studies, several steels have been tested at laboratory scale in a simulated gas atmosphere of a pyrolysis process of anthropogenic resources. In this paper, we propose a model on the course of corrosion in a H₂S and HCl-containing atmosphere for N10276, which contains, besides iron, chromium, and nickel, also molybdenum as main alloying element. Bearing in mind the impact of the main alloying elements, as well as thermodynamic considerations and kinetic effects, the corrosion behavior of N10276 in a H₂S and HCl-containing atmosphere at 480 °C and 680 °C can be explained. In addition, the corrosion behavior of N10276 is compared with earlier tested Fe-Cr-Ni alloys and differences in the corrosion behavior are stated within this paper. Full article