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Review

Corrosion and Protection of Chinese Bronze Relics: A Review

by
Lingling Zhang
1,
Chao Yang
2,* and
Yingzhi Guo
3,*
1
School of Management, Putian University, Putian 351100, China
2
National Engineering Research Center of Light Alloy Net Forming, School of Materials Science and Engineering, Shanghai 200240, China
3
The Department of Tourism, Fudan University, Shanghai 200433, China
*
Authors to whom correspondence should be addressed.
Coatings 2024, 14(9), 1196; https://doi.org/10.3390/coatings14091196
Submission received: 28 August 2024 / Revised: 11 September 2024 / Accepted: 12 September 2024 / Published: 17 September 2024
(This article belongs to the Special Issue Enhanced Mechanical Properties of Metals by Surface Treatments)
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Abstract

:
The corrosion problem affecting ancient Chinese bronze relics and the protective measures required post-excavation are crucial for the study of historical cultural heritage and for ensuring heritage revitalization and sustainable development. This work includes a statistical analysis, clusters information, and thoroughly examines international research on bronze relic corrosion and protection. It delves into the timeline and trends of research, the main countries leading the research efforts, the research content, and the relationships between these factors. A comprehensive review is provided on the corrosion principles, materials, detection methods, and protection techniques for bronze. The study explores the corrosion principles and processes of bronze from a materials science perspective both before and after excavation. It summarizes non-destructive detection methods and examines specific factors that influence corrosion. Furthermore, the article reviews current corrosion protection methods for bronze and related protection materials, including commonly used strategies such as surface corrosion inhibitors and organic resin coatings for protection. It also discusses the potential application of advanced corrosion protection methods in the realm of metal materials in recent years to safeguard bronze. Proposing innovative solutions, the study suggests the possibility of constructing biomimetic superhydrophobic surfaces to create a barrier isolating humid air from contacting bronze materials, thereby reducing the adhesion of corrosive media to the substrate and significantly diminishing the likelihood of corrosion. In conclusion, the article looks towards the future, considering the challenges and potential development directions for the corrosion protection of bronze and related protection materials.

1. Introduction

In the historical development of China, bronze has played a significant role, serving as a symbol of ancient Chinese civilization and as a component of historical and cultural heritage with significant archaeological value [1]. However, both pre-/post-excavation corrosion can cause damage to the surface inscriptions, symbols, and overall integrity of bronze, leading to a loss of their historical and cultural significance [2]. In many instances, sudden and significant environmental changes before and after excavation can worsen the corrosion of bronze. If inappropriate protection methods are employed, the irreversible damage can be exacerbated [3,4]. Unearthed bronze generally has a naturally formed “patina” corrosion product protective layer on its surface, primarily composed of basic copper carbonate (Cu2(OH)2CO3) (Figure 1). It is crucial to note that the patina protective layer can also be corroded in different environments, leading to the formation of destructive local corrosion products like CuCl and Cu2(OH)3Cl in chlorine ion environments. These products further accelerate the corrosion process of the artifacts [5]. Therefore, a deep understanding of the corrosion process of bronze, an analysis of the types of corrosion product presents on the artifact surface, an exploration of the effects of corrosion products such as patina, and the development of effective surface corrosion protection methods are essential in preserving these valuable historical and cultural artifacts.

2. Research Statistics on the Corrosion and Protection of Bronze Relics

The phrase “bronze corrosion or bronze corrode” was used as a “Topic” (searches title, abstract, keyword plus, and author keywords) to search the Web of Science (WoS) Core Collection on 24 August 2024. The Citespace 6.3.R6 software was used to analyze the data on bronze corrosion papers. A total of 1899 papers from 1906 to 2024 were obtained.
According to Figure 2, the first bronze corrosion paper was published in 1906. Before 1990, the annual publication volume did not exceed five articles, showing a flat upward and downward fluctuation trend. After 1991, the overall number of studies showed an upward trend. Among them, the period from 1991 to 2006 showed a slow upward trend, while the overall upward trend was relatively fast after 2007, breaking through 100 articles and reaching 114 publications in 2018. Since then, it has still received a lot of attention. However, the first bronze corrosion protection paper was published in 1991. The overall number of studies showed a steady upward trend. This highlights the historical attention to the issue of corrosion in bronze relics since their excavation, but the protection against it has consistently fallen behind. This has resulted in the early corrosion of many bronze relics post-excavation, diminishing their cultural and historical value. In recent years, there has been a growing focus on corrosion protection, with researchers acknowledging the severity of corrosion and the importance of protection. New corrosion protection methods have been developed, allowing many bronze relics to be safeguarded immediately after excavation, preventing irreversible harm. The research trends suggest that future studies on the corrosion and protection of bronze relics will become increasingly scientific and effective.
The distributions of countries that published bronze corrosion papers were analyzed based on the abovementioned literature search results. Figure 3 shows the network visualization among different countries (regions) that published at least 10 bronze corrosion papers. The font size and circle area size represent the number of published papers while the circle area colors indicate the year, and the link lines among different countries (regions) indicate the collaboration activity. The top five countries (regions) that published bronze corrosion papers were China, Italy, the USA, England, and Spain. China published the most bronze corrosion papers with 402, while the second country was Italy with 279 papers. In addition, France, Germany, Italy, the USA, and China have many international collaborations with other countries or regions. This trend indicates a move towards increased international cooperation in the research on bronze corrosion and protection. Sharing data is beneficial for enhancing research efforts and speeding up progress.
Figure 4 shows the network visualization among different keywords in bronze corrosion-related papers. From 1906 to 2024, the top six keywords were copper, behavior, alloy, corrosion, microstructure, and bronze. The word “copper” appears 295 times, behavior appears 240 times, and alloy appears 220 times, which means they are still the research hotspots. In addition, “protection” or “conservation” appear 96 times. This indicates that the protection and conservation of bronzeware corrosion have also attracted the attention of scholars. The keywords of the aforementioned research are primarily focused on the corrosion of bronze. Researchers have analyzed the mechanisms of bronze corrosion from various perspectives, including corrosion behavior, alloy composition, and influencing factors such as microstructure. Additionally, the protection of bronze from corrosion has also garnered the attention of scholars, although research in this area has not yet exceeded that of corrosion itself. This is due to the relatively recent start of research on corrosion protection. As scholars have increasingly recognized the importance of safeguarding bronze against corrosion, protective strategies have begun to evolve.
Figure 5 shows the clusters of keywords in bronze corrosion-related papers. By classifying the keywords and analyzing the related literature, the research on bronze corrosion could be generally grouped into 17 categories. The first is wear with 43 keywords, including resistance, layer, performance, friction, etc. The second is etruscan with 37 keywords, including alloy, aluminum bronze, copper alloy, etc. The third is copper corrosion with 37 keywords, including natural patina, copper corrosion, protection, etc. In addition, the thirteenth is cultural heritage with 23 keywords, including surface, cultural heritage, environment, etc. The results above reveal that researchers have studied bronze from multiple dimensions and perspectives, covering its various types, destructive nature, sustainability, cultural dissemination, and more. However, all of these aspects are ultimately related to its corrosion and protection.

3. Corrosion and Detection of Bronze Relics

In ancient China, bronze from various periods was primarily made of copper–tin–lead alloys. Aside from Cu, Sn, and Pb as the main elements, they also incorporated trace amounts (less than 1 wt.%) of Zn, As, Sb, Fe, and other elements [6]. Bronze with varying metal element compositions can undergo corrosion in various environments, typically categorized as localized rust corrosion and uniform rust corrosion. The types of corrosion products produced have different impacts on the preservation of the bronze matrix. Generally, unearthed bronze is coated with one or more layers of corrosion products (Figure 6) [5]. Based on their corrosive effects, these products can be categorized as either harmless or harmful. Harmless corrosion products typically comprise layers that shield the copper matrix, such as CuO, Cu2O, Cu2(OH)2CO3, and oxides of alloy elements like SnO2. These products create a dense film on the matrix’s surface, preventing further corrosion [7]. In contrast, harmful corrosion products like Cu2(OH)3Cl, which contain chloride, can expedite localized corrosion and inflict significant harm on the bronze, often referred to as “bronze disease” [8]. The underlying principle is that the onset of localized corrosion generates a loose green corrosion product (Cu2(OH)3Cl), which gradually spreads to other areas of the artifacts, expediting the corrosion process. Therefore, comprehending the corrosion mechanisms and processes of bronze is imperative for their preservation.

3.1. Corrosion Mechanism

The local corrosion of bronze cultural relics typically involves three main types: electrochemical corrosion, localized pitting, and intergranular corrosion, with electrochemical corrosion being the most prevalent form.
Bronze is primarily composed of a three-element alloy of Cu, Sn, and Pb. Along with solid solutions and precipitates on the surface, there are also trace amounts of metallic Pb. The differences in standard electrode potentials between these elements create a scenario where bronze relics can develop micro-batteries on their surfaces in corrosive environments, leading to electrochemical corrosion [9]. In environments containing Cl−, bronze may react with Cl− to form CuCl corrosion products on their surfaces. Subsequent exposure to factors such as oxygen and moisture during excavation can lead to the formation of weaknesses in the CuCl film, facilitating the development of “bronze disease”. Excessive water can cause the hydrolysis of CuCl into Cu2O and HCl, while in oxygen-rich conditions, Cu2O will react with HCl, O2, and H2O to form bright green dot-like (Cu2(OH)3Cl). The lower density of corrosion products compared to bronze metal can also result in stress cracks on the surface, allowing environmental media such as Cl−, H2O, and O2 to further accelerate corrosion. The specific corrosion mechanisms are outlined in Formulas (1)–(3) below:
Cu + Cl− → CuCl + e−
2 CuCl + H2O → Cu2O + 2HCl
2Cu2O + 2HCl + O2 + 2H2O → 2(Cu2(OH)3Cl)
However, when carbon dioxide is present in the environment, Cu2O will react with water and carbon dioxide to form the blue-green complex corrosion products Cu2(OH)2CO3 and Cu3(OH)2(CO3)2, as shown in Reactions (4) and (5):
2Cu2O + 2CO2 + O2 + 2H2O → 2Cu2(OH)2CO3
6Cu2O + 8CO2 + 3O2 + 4H2O → 4Cu3(OH)2(CO3)2
The corrosion reaction occurs relatively quickly, causing the surface film of bronze to gradually crack. With an increase in Cl− on the surface, corrosion continues to penetrate deeper into the matrix, eventually resulting in perforation, cracking, and other forms of severe corrosion in bronze.
Apart from electrochemical corrosion, micro-battery reactions also take place between different phases in the alloy, such as the typical electrochemical reaction between PbO and Sn. In this reaction, Pb is easily oxidized to form PbO in the presence of air, while Sn is less prone to oxidation. These two substances create a micro-battery within the bronze relics, leading to corrosion. The specific corrosion mechanism is illustrated in Formulas (6) and (7):
PbO + H2O + 2e− → Pb + 2OH−
Sn → Sn2+ + 2e−
In environments containing Cl− and water, tin reacts to form SnCl2, which further combines with Cl− to form the complex ion SnCl42−, causing widespread corrosion known as “pitting corrosion”. Pitting corrosion often occurs on the surface of bronze, where tin near lead oxide films gradually oxidizes to SnCl2, and with the enrichment of Cl−, pitting corrosion spreads along the distribution of tin in the coexisting microstructure. Additionally, the Cl− enriched at the pitting location accelerates the electrochemical corrosion process of copper.
Furthermore, intergranular corrosion is another form of corrosion behavior in bronze. Typically, Cl− infiltrates longitudinally into the matrix along gaps and defects, then corrodes along the high energy interfaces forming corrosion [10]. Bronze generally consists of three single-phase alloys, α, β, and δ, and these three single-phase alloys have a potential difference, leading to electrochemical corrosion. Among them, the β phase is unstable and easily forms a galvanic cell with the α phase, leading to corrosion. After the β phase is corroded, the nearby δ phase will be subsequently corroded. Therefore, intergranular corrosion in bronze continues to corrode the matrix along the α phase boundaries. Additionally, corrosion typically progresses inward along the shortest path, such as grain boundary slip zones and twinning boundaries, where Cl−, oxygen, and other media enter the metal matrix. More active metals undergo oxidation first, with tin in the bronze alloy reacting to generate a thin, porous layer of nanoscale SnO2. This oxide layer is relatively stable but is weakened by a hydration process that weakens its inhibitory effect, causing copper to oxidize into copper ions and migrate to the surface in the opposite direction to oxygen anions. The corrosion process gradually progresses from the surface inward, eventually forming various copper compounds such as Cu2(OH)2CO3, Cu2(OH)3Cl, and CuSO4(OH)6 depending on the environment in which the bronze relics are located.
Currently, the above three corrosion mechanisms cannot fully explain the corrosion process of bronze. They should occur in a mutually coupled manner, where electrochemical corrosion explains the corrosion process of the copper matrix, pitting explains the corrosion effects between other elements in the alloy, and intergranular corrosion focuses on the influence of matrix organization and structure on corrosion.

3.2. Corrosion Detection Methods

For the detection of corrosion in bronze cultural relics, non-destructive testing techniques are primarily utilized, such as X-ray fluorescence technology (XRF), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and others [11]. Among these, XRF technology is based on the interaction between the incident X-ray beam and the elemental atoms present in the sample, resulting in the emission of characteristic X-rays (Figure 7), which are used to determine the elemental composition of the material being analyzed. Furthermore, quantitative analysis can be carried out by measuring the intensity of peaks in the spectrum, making it a widely used method in the examination of artwork and historical artifacts. In addition to its non-destructive nature, one of the major advantages of XRF technology is the portability of the equipment, allowing for on-site analysis. This feature makes it particularly suitable for archaeologists conducting field exploration.
In addition, coatings containing fluorescent or chromogenic indicators have recently garnered great attention due to their visual and non-destructive characteristics [12]. These coatings can selectively respond to pH, metal ions, and electrochemical reactions related to corrosion processes, leading to color changes or fluorescent responses. They have been successfully applied to detect corrosion layers on bronze (Figure 8). Fluorescence probe technology has seen widespread use in various fields including chemistry, biology, medicine, and the environment in recent years [13]. Its advantages include high sensitivity, high specificity, high selectivity, and rapid response. Fluorescence-based corrosion detection is considered an early warning technology, relying on fluorescence changes caused by the corrosion process to evaluate the extent of substrate material corrosion [14]. In the past few decades, fluorescence detection applications for the corrosion of iron, aluminum, magnesium, and copper metals have been extensively documented. Overall, fluorescence-based corrosion detection offers a handheld or portable device inspection method with numerous benefits, including simple operation, non-destructiveness, real-time results, and more accurate detection compared to other complex and challenging corrosion detection technologies.

3.3. Corrosion-Influencing Factors

The factors affecting the corrosion of bronze include the matrix and the environment, with the matrix mainly consisting of alloy composition and structure, and the environment mainly being the soil environment. The effects of alloy composition on bronze corrosion include two points: (1) bronze alloy composition directly participates in electrochemical corrosion reactions, which may accelerate or decelerate corrosion, and (2) alloy composition determines the microstructure composition and distribution of bronze, indirectly affecting the corrosion process [15]. Studies have found that adding certain metals to pure copper can significantly enhance its properties, such as Sn reducing the melting point of bronze, reducing linear shrinkage, and increasing strength. However, as the Sn content increases, the ductility of bronze decreases [16]. Pb can increase alloy fluidity, which is advantageous for casting complex-structured bronze, but with increasing Pb content, both strength and ductility decrease [17]. However, excavated bronze exhibits different degrees of corrosion due to varying Sn and Pb content, with bronze with higher Sn content generally corroding less than bronze with lower Sn content. Additionally, due to compositional segregation in different locations, the presence of oxides or sulfides, and impurities introduced during formation and surface processing, different locations of bronze may exhibit varying degrees of corrosion [18]. Since Pb exists as an independent phase in copper–tin alloys, when analyzing the composition of Cu–Sn–Pb ternary bronze, the analysis mainly focuses on the Cu–Sn binary alloy [19]. Typically, the solubility of Sn in α-Cu solid solution is the highest, and due to the slow diffusion rate of Sn atoms in copper, when the Sn content is below 5%, the as-cast structure is an α phase solid solution, while at 5%–15% Sn content, the as-cast structure is a mixture of α and (α + δ) phases, where the α phase is a solid solution formed by Sn dissolved in copper, and the δ phase is the metal compound Cu31Sn8. When the Sn content exceeds 15%, the number of coexisting phases increases, resulting in a multiphase structure of a rich copper phase α, a rich tin (α + δ) eutectic phase, and a free lead phase in Cu–Sn–Pb bronze. Typically, higher energy exists at grain boundaries and phase boundaries, making corrosion prone to occur, with a large number of corrosion microcells inevitably existing between different phases, accelerating corrosion or causing localized corrosion.
The soil environment is the primary corrosion medium for bronze, and soil is a highly complex medium for corrosion. Factors such as moisture, anions, oxygen content, acidity, alkalinity, and temperature in the soil all play a role in affecting the corrosion of bronze [20]. Generally, bronze corrodes much faster in acidic soil compared to neutral or alkaline soil [21]. Anions in the soil also greatly influence corrosion, as corrosive anions can directly participate in the electrochemical corrosion process in the soil. Chlorine ions, for example, not only accelerate the anodic process of corrosion, but also penetrate the corrosion layer, making the soil more corrosive with higher chlorine ion content [22]. Studies on the corrosion process of bronze in different pH values and chlorine ion concentrations using electrochemical methods have shown that the pH of the solution mainly impacts whether protective corrosion products can form on the bronze [23]. A higher concentration of chlorine ions in the corrosion medium leads to a higher corrosion rate of bronze, potentially causing severe bronze disease. The effects of chlorine ions on corrosion in media with varying acidity and alkalinity also differ. In a weak acid, high chlorine corrosion medium, bronze corrosion is severe due to the formation of a large amount of chlorine-containing corrosion products [24]. In an alkaline, high chlorine corrosion medium, some artifacts may still remain in relatively good condition with only a layer of cuprous oxide corrosion product. This indicates that if the high concentration of chlorine ions present does not contribute to harmful chlorine-containing corrosion product formation on the bronze relic’s surface, the corrosion may be less severe. However, when bronze is unearthed and the removal of chlorine salts is incomplete, it may quickly corrode in a high-humidity, oxygen-rich environment [25].

4. Corrosion Protection Strategy

During the excavation of numerous bronzes, they often experience sudden environmental changes upon discovery, which can result in accelerated corrosion or oxidation. To protect bronze from corrosion, it is crucial to prevent exposure to Cl− and moisture. Therefore, it is essential to utilize scientifically sound techniques and processes for corrosion protection. Common methods currently employed include surface corrosion inhibitor protection, organic resin coating protection, and advanced biomimetic superhydrophobic surface protection.

4.1. Surface Corrosion Inhibitor

In recent years, the methods for protecting bronze have evolved from simply removing corrosive products to the development of surface chemical corrosion inhibitors, which have now become the most commonly used means of corrosion protection for bronze [26]. The mechanism of action of corrosion inhibitors on the surface of bronze involves adsorption and coordination with the metal surface, forming a polymer film tightly bound to copper ions on the surface of bronze. This film encapsulates the exposed copper ions, preventing the spread of “bronze disease” to the inner copper metal [27]. It also effectively prevents harmful substances such as O2, H2O, CO2, and SO2 from further corroding the bronze. Additionally, the Cl− produced during the reaction process is removed during cleaning, reducing the accelerated corrosion of bronze. Common industrial corrosion inhibitors include benzotriazole (BTA), 2-amino-5-mercapto-1,3,4-thiadiazole (AMT), acrylic resin, and other pi-pi conjugated systems [28,29]. Pi-pi conjugated systems have the characteristic of making the electrons on the heteroatoms in the corrosion inhibitor more prone to delocalization, allowing the p-electrons to transfer to copper atoms and ions, forming a coordination bond. This facilitates the transfer of electrons from unoxidized copper atoms to the empty orbitals of the corrosion inhibitor molecules, enabling the stable and effective adsorption of the corrosion inhibitor molecules on the surface of copper atoms. This prevents the corrosion medium from diffusing to surrounding copper atoms, ultimately inhibiting further corrosion [30].
The majority of corrosion inhibitors used in industry are toxic to the environment and humans, so it is necessary to find environmentally friendly corrosion inhibitors. In recent years, research has found that amino acids, due to their non-toxicity, good biocompatibility, ease of production, and excellent water solubility, have become promising corrosion inhibitors in this field [31]. For example, Ismail et al. studied the corrosion inhibition effect of the bio-safe cysteine on copper surfaces using electrochemical methods [32]. The results showed that cysteine could achieve corrosion inhibition in Cl− ion solutions (0.6 M and 1 M) with an efficiency of around 84%. Singh et al. investigated the role of benzaldehyde and the salicylaldehyde derivative sulfaphenazole (SB) as corrosion inhibitors using weight loss, electrochemical, and surface analysis methods [33]. The results showed that with an increase in the concentration of corrosion inhibitors, the corrosion inhibition effect was gradually enhanced. At a concentration of 0.129 mM H2SO4, both inhibitors exhibited the highest corrosion inhibition efficiency of 99.03% and 97.98%, respectively. Wang et al. studied the mechanism of action of cysteine on the surface of bronze coated with artificial copper green [34]. The electrochemical results showed that cysteine significantly stabilized the corrosion behavior of the CuCl corrosion product layer, acting as a corrosion inhibitor. Commonly used cysteines include CYS and CYB, as shown in Figure 9. Zhu et al. investigated the corrosion inhibition effect of imidazoline oleate (OIM) and L-cysteine (CYS) in a 3.5 wt.% NaCl solution and found that the composite inhibitor had a better effect than a single inhibitor [35]. They found that the best corrosion inhibitory effect of the composite inhibitor was achieved when the mass ratio of OIM to CYS was 3:1, reaching a corrosion inhibition efficiency of 95.08%. This synergistic enhancement effect can be attributed to a dual-layer adsorption mechanism. Han discussed the corrosion inhibition mechanism of environmentally friendly L-cysteine (CYB) modified Schiff base and hexadecylamine (HC10) as inhibitors for corrosion on bronze in a 3.5 wt.% NaCl solution [36]. The results showed that these two molecules competitively adsorbed and collaboratively hindered corrosion, while also demonstrating high penetrability and enhanced performance.

4.2. Organic Resin Coating

Epoxy resin boasts excellent mechanical properties, low shrinkage, low residual stress, good heat resistance, and corrosion resistance, making it a crucial material for restoring bronze in cultural heritage conservation [37,38]. Clear and transparent epoxy resins are especially popular for consolidating and bonding fragments during restoration projects [39,40]. The structure of epoxy resin includes an epoxy functional group and aliphatic, aromatic, and heterocyclic structures, resulting in various physical properties. Bisphenol A-type epoxy resin is the most commonly employed in cultural heritage conservation, typically combined with a curing agent to form hardened surface coatings for protective purposes [41]. Despite its benefits, epoxy resin does come with drawbacks, like vulnerability to ultraviolet radiation, degradation, and low impact resistance [42]. As a result, modifications are often essential when utilizing epoxy resin in cultural heritage conservation efforts.
The aggregated cube octamethyl octasiloxane modified epoxy resin (POSS) has garnered significant attention [43], as depicted in Figure 10. Generally, modified epoxy resin exhibits good heat resistance and dielectric properties. By reducing the degree of cross-linking in the epoxy resin, the toughness of the material can be enhanced. Jerman et al. conducted a study on the corrosion inhibition effect of coatings prepared with silane-functionalized U2IO6 POSS on AA 2024-T3 alloy [44]. The results demonstrated that the coating displayed a strong barrier effect, leading to a significant decrease in anodic current density by nearly 102 times, indicating a remarkable corrosion inhibition effect. Additionally, the toughness of epoxy resin can also be improved through block copolymer modification. Common block copolymers include n-butyl acrylate (nBA), methyl methacrylate (MMA), and glycidyl methacrylate (GMA), among others. Liu et al. utilized a 5% loaded poly(ethylene-propylene)-b-poly(ethylene oxide) (PEP-PEO) block copolymer to toughen bisphenol A epoxy resin [45]. The findings revealed that the PEP-PEO block copolymer notably increased the fracture toughness of the epoxy resin. Pang et al. modified epoxy resin with inorganic nano SiO2 particles and PEP-PEO block copolymers. It was observed that with a low concentration of the block copolymer, KIC increased linearly with the concentration of nano SiO2, resulting in a nearly 50% increase in toughness when the concentration of nano SiO2 reached 45% [46]. Brifa et al. applied water-based epoxy silicate consolidants to Globigerina Limestone (GL), leading to reduced water absorption and a significant enhancement in the material’s mechanical properties [47].

4.3. Bionic Superhydrophobic Surface

Recently, surface superhydrophobic technology inspired by lotus leaves has gained widespread attention and is considered to be a highly effective and feasible method for preventing the corrosion of bronze. This technology also exhibits anti-fouling and self-cleaning properties [48]. It is generally believed that the micro-nano structures on the superhydrophobic metal surface can increase its static contact angle, and the air layer on the surface can effectively block corrosive liquids from coming into contact with the metal substrate, thus achieving a corrosion prevention effect (Figure 11) [49].
To prepare superhydrophobic films on bronze with minimal damage, methods such as immersion or spray coating are commonly used. The preparation of superhydrophobic surfaces on copper mainly involves a two-step method and a one-step method. The former includes processes such as chemical etching, surface oxidation, or chemical/electrochemical deposition to create dual-sized micro-nano structures on copper surfaces, followed by modification with a low surface energy material [50,51,52,53]. For example, Yuan et al. grew dense nano-wire structures on the Cu surface through anodization, and then modified it with a fluoroalkylsilane ethanol solution to achieve a contact angle of approximately 160°, significantly improving the material’s electrochemical potential and corrosion resistance [49]. Similarly, Qian et al. obtained nanostructures on copper surfaces through chemical etching and then modified the surface with fluoride to achieve a low surface energy superhydrophobic surface, greatly enhancing the corrosion resistance of the copper substrate [54]. Liu et al. used electrochemical deposition to prepare nanostructured copper surfaces, followed by modification with low surface energy 1-octadecanethiol to achieve a superhydrophobic surface with a water contact angle of 152.4°, significantly enhancing the copper surface’s corrosion resistance [55]. Although the two-step method is simple to operate, it is time-consuming. In recent years, a one-step method has been developed to directly synthesize micro-nano structures with low surface energy on copper surfaces in one step. Jiang et al. immersed copper surfaces in a solution of stearic acid ethanol, leading to the spontaneous growth of stearic acid copper nanosheets with low surface energy and micro-nano structures, exhibiting strong superhydrophobic properties [56]. Furthermore, Rao et al. mixed methyltriethoxysilane (MTES), methanol (MeOH), and water in specific proportions to prepare a hydrophobic sol, which was then deposited on a copper substrate by spin coating, achieving a static water contact angle as high as 155° and a low sliding angle of 7° on the superhydrophobic surface [57]. This material still exhibited excellent corrosion resistance after being immersed in an HCl solution for 100 h.
Based on the information provided, creating a superhydrophobic structure on the surface of copper can greatly improve its corrosion resistance. However, the mechanical properties of the surface nanostructure are inadequate, which makes it susceptible to failure upon friction. Therefore, when applying superhydrophobic surface treatment to bronze, it is crucial to prevent collisions to prevent corrosion from occurring at the point of failure, as this can lead to accelerated localized corrosion over time.

5. Prospect

Research on the corrosion of ancient Chinese bronze has been conducted internationally for over 100 years. However, the study of protecting it from corrosion started relatively late, resulting in irreversible damage to many artifacts after excavation. This serves as a valuable lesson for excavation workers: effective and rational protection plans should be developed before excavating artifacts to minimize damage. Currently, researchers have made significant progress in understanding bronze relics corrosion mechanisms and have developed effective protection strategies after corrosion occurs. However, the corrosion behavior of bronze in different environments varies greatly. Utilizing a big data platform to construct a globally shared corrosion data set is an effective means to further study corrosion mechanisms. While corrosion detection meets non-destructive testing requirements, the real-time monitoring of corrosion after the excavation of bronze lacks research and methods, presenting a challenge for corrosion researchers in the future. Furthermore, although bronze can generally be protected after excavation, there are some shortcomings in the methods used for corrosion protection. For example, corrosion inhibitors typically cause surface damage to workpieces. Developing a new generation of corrosion inhibitors without surface damage is the future direction of development. Organic resin materials are commonly used for protection, but their durability is lower than that of inorganic materials, making it difficult to assess their long-term effectiveness. In the future, inorganic materials can be used to modify epoxy resins to enhance durability, and synthetic artifacts can be used for long-term testing. While superhydrophobic coatings offer excellent protective performance, their mechanical properties are lacking, and the surface’s micro-nano structure can easily be damaged. Developing wear-resistant superhydrophobic coatings is the trend for future development. Additionally, researchers should focus on corrosion caused by surface microorganisms on bronze and construct functional antibacterial and corrosion-resistant dual-function coatings for long-term corrosion prevention.

Author Contributions

Conceptualization, L.Z. and C.Y.; methodology, L.Z.; software, L.Z. and C.Y.; validation, Y.G. and L.Z.; formal analysis, C.Y.; investigation, C.Y.; resources, L.Z.; data curation, L.Z. and C.Y.; writing—original draft preparation, L.Z. and C.Y.; writing—review and editing, C.Y. and Y.G.; visualization, Y.G.; supervision, Y.G.; project administration, L.Z., Y.G. and C.Y.; funding acquisition, L.Z., C.Y. and Y.G. All authors have read and agreed to the published version of the manuscript.

Funding

This work was financially supported by the National Natural Science Foundation of China (Yingzhi Guo, 72074053), and the Social Science Foundation of Fujian Province (Lingling Zhang, FJ2024BF046).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data are contained within the article.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Hu, Y.; Wei, Y.; Li, L.; Zhang, J.; Chen, J. Same site, different corrosion phenomena caused by chloride: The effect of the archaeological context on bronzes from Sujialong Cemetery. China J. Cult. Herit. 2021, 52, 23–30. [Google Scholar] [CrossRef]
  2. Quaranta, M.; Catelli, E.; Prati, S.; Sciutto, G.; Mazzeo, R. Chinese archaeological artefacts: Microstructure and corrosion behaviour of high-leaded bronzes. J. Cult. Herit. 2014, 15, 283–291. [Google Scholar] [CrossRef]
  3. Chiavari, C.; Martini, C.; Balbo, A.; Monticelli, C.; Velino, C.; Masi, G.; Bernardi, E. Atmospheric corrosion of Cu-Si-Mn bronze for contemporary art under simulated runoff and continuous immersion conditions. Corros. Sci. 2022, 205, 110442. [Google Scholar] [CrossRef]
  4. Liu, Y.W.; Yu, G.C.; Cao, G.W.; Wang, C.; Wang, Z.Y. Characterization of corrosion products formed on tin-bronze after 29 years of exposure to Shenyang, China. J. Mater. Res. Technol. 2023, 23, 5270–5279. [Google Scholar] [CrossRef]
  5. Robbiola, L.; Blengino, J.M.; Fiaud, C. Morphology and mechanisms of formation of natural patinas on archaeological Cu-Sn alloys. Corros. Sci. 1998, 40, 2083–2111. [Google Scholar] [CrossRef]
  6. Lin, J.L.; Wang, Y.K.; Liu, S.R.; Qian, W. Evaluating accuracy and inter-laboratory reproducibility of the compositional analysis of ancient bronzes. AIA 2023, 4, 100027. [Google Scholar] [CrossRef]
  7. Fan, M.; Cui, Y.; Zhang, Z.; Liu, L.; Li, Q.; Luo, Q. Enhanced oxidation resistance in Mg-Y-Zn-Ho alloys via introducing dense low-oxygen-diffusion Ho2O3 oxide film. Corros. Sci. 2023, 213, 110970. [Google Scholar] [CrossRef]
  8. Liu, W.; Li, M.; Wu, N.; Liu, S.; Chen, J. A new application of fiber optics reflection spectroscopy (FORS): Identification of “bronze disease” induced corrosion products on ancient bronzes. J. Cult. Herit. 2021, 49, 19–27. [Google Scholar] [CrossRef]
  9. Morshed-Behbahani, K.; Rayner, A.J.; Bishop, D.P.; Nasiri, A. Perspectives on the unusual electrochemical corrosion of Nickel Aluminum Bronze (NAB) alloy fabricated through laser-powder bed fusion additive manufacturing. Corros. Sci. 2024, 228, 111846. [Google Scholar] [CrossRef]
  10. Bannister, C.O.; Newcomer, J.A. Examination of Bronze Implements. Nature 1925, 116, 786–789. [Google Scholar] [CrossRef]
  11. Silveira, P.; Falcade, T. Applications of energy dispersive X-ray fluorescence technique in metallic cultural heritage studies. J. Cult. Herit. 2022, 57, 243–255. [Google Scholar] [CrossRef]
  12. Augustyniak, A.; Ming, W.H. Early detection of aluminum corrosion via “turn-on” fluorescence in smart coatings. Prog. Org. Coat. 2011, 71, 406–412. [Google Scholar] [CrossRef]
  13. Ye, J.W.; Zhao, L.M.; Bogale, R.F.; Gao, Y.; Wang, X.X.; Qian, X.M.; Guo, S.; Zhao, J.Z.; Ning, G.L. Highly selective detection of 2,4,6-trinitrophenol and Cu2+ ions based on a fluorescent cadmium-pamoate metal-organic framework. Chem.-Eur. J. 2015, 21, 2029–2037. [Google Scholar] [CrossRef] [PubMed]
  14. Wang, H.; Fan, Y.; Tian, L.M.; Zhao, J.; Ren, L.Q. Colorimetric/fluorescent dual channel sensitive coating for early detection of copper alloy corrosion. Mater. Lett. 2020, 265, 127419. [Google Scholar] [CrossRef]
  15. Figueiredo, E.; Silva, R.J.C.; Fernandes, F.M.B.; Araújo, M.F. Some long term corrosion patterns in archaeological metal artefacts. MSF 2010, 636–637, 1030–1035. [Google Scholar] [CrossRef]
  16. Mabille, I.; Bertrand, A.; Sutter, E.M.M.; Fiaud, C. Mechanism of dissolution of a Cu–13Sn alloy in low aggressive conditions. Corros. Sci. 2003, 45, 855–866. [Google Scholar] [CrossRef]
  17. Wang, Y.; Jing, H.; Mehta, V.; Welter, G.J.; Giammar, D.E. Impact of galvanic corrosion on lead release from aged lead service lines. Water. Res. 2012, 46, 5049–5060. [Google Scholar] [CrossRef]
  18. Wang, X.Y.; Zhou, H.R.; Song, J.L.; Fan, Z.L.; Zhang, L.M.; Shi, J.R.; Chen, J.C.; Xiao, K. Mechanism of corrosion behavior between Pb-rich phase and Cu-rich structure of high Sn–Pb bronze alloy in neutral salt spray environment. J. Mater. Res. Technol. 2024, 29, 881–896. [Google Scholar] [CrossRef]
  19. Ren, X.Y.; Shi, Z.H.; Zhang, G.W.; Chen, N.N.; Zhang, Y.G.; Guo, Z.M.; Hu, J.Z.; Xu, H. Strengthening mechanism of sub-nano Ni3P and Cu3P phases particles on the Pb–Sn bronze alloy. Heliyon 2024, 10, e34624. [Google Scholar] [CrossRef]
  20. Boccaccini, F.; Riccucci, C.; Messina, E.; Pascucci, M.; Bosi, F.; Chelazzi, D.; Guaragnone, T.; Baglioni, P.; Ingo, G.M.; Carlo, G.D. Reproducing bronze archaeological patinas through intentional burial: A comparison between short- and long-term interactions with soil. Heliyon 2023, 9, e19626. [Google Scholar] [CrossRef]
  21. Liang, Z.P.; Jiang, K.X.; Zhang, T.A. Corrosion behaviour of lead bronze from the Western Zhou Dynasty in an archaeological-soil medium. Corros. Sci. 2021, 191, 109721. [Google Scholar] [CrossRef]
  22. Oudbashi, O.; Emami, S.; Ahmadi, H.; Davami, P. Micro-stratigraphical investigation on corrosion layers in ancient Bronze artefacts by scanning electron microscopy energy dispersive spectrometry and optical microscopy. Herit. Sci. 2013, 1, 21. [Google Scholar] [CrossRef]
  23. Turo, F.D.; Coletti, F.; Vito, C.D. Investigations on alloy-burial environment interaction of archaeological bronze coins. Microchem. J. 2020, 157, 104882. [Google Scholar] [CrossRef]
  24. Said, M.; Nazeri, M.F.M.; Sharif, N.M.; Kheawhom, S.; Mohamad, A.A. Corrosion properties of Cu/Sn–3.0Ag–0.5Cu/Cu solder butt joints fabricated by conventional reflow and microwave hybrid heating. Corros. Sci. 2022, 208, 110641. [Google Scholar] [CrossRef]
  25. Amegroud, H.; Boudalia, M.; Elhawary, M.; Garcia, A.J.; Bellaouchou, A.; Amin, H.M.A. Electropolymerized conducting polyaniline coating on nickel-aluminum bronze alloy for improved corrosion resistance in marine environment. Colloid. Surface A 2024, 691, 133909. [Google Scholar] [CrossRef]
  26. Novakovic, J.; Papadopoulou, O.; Vassiliou, P.; Filippaki, E.; Bassiakos, Y. Plasma reduction of bronze corrosion developed under long-term artificial ageing. Anal. Bioanal. Chem. 2009, 395, 2235–2244. [Google Scholar] [CrossRef]
  27. Ma, H.; Chen, S.; Niu, L.; Zhao, S.; Li, S.; Li, D. Inhibition of copper corrosion by several Schiff bases in aerated halide solutions. J. Appl. Electrochem. 2002, 32, 65–72. [Google Scholar] [CrossRef]
  28. Wang, Z.; Cheng, J.; Wang, Y.; Cao, C.; Li, L. Research progress on copper corrosion protection and corrosion inhibitors. Mater. Protect. 2021, 54, 160–166. [Google Scholar]
  29. Han, Z.F.; Huang, X.; Chen, J.C.; Chen, J.Y. 2-Mercaptob enzimidazole compounded with the conventional sealer B72 for the protection of rusted bronze. J. Cult. Herit. 2024, 67, 42–52. [Google Scholar] [CrossRef]
  30. Jin, J.Y.; Yin, H.; Shi, N.Q.; Luo, H.X.; Li, X.; Li, H.Y. Efficient self-healing coatings embedded with polydopamine modified BTA@DMSNs for corrosion protection. Prog. Org. Coat. 2024, 191, 108426. [Google Scholar] [CrossRef]
  31. Messali, M.; Larouj, M.; Lgaz, H.; Rezki, N.; Al-Blewi, F.F.; Aouad, M.R.; Chaouiki, A.; Salghi, R.; Chung, I.M. A new schiff base derivative as an effective corrosion inhibitor for mild steel in acidic media: Experimental and computer simulations studies. J. Mol. Struct. 2018, 1168, 39–48. [Google Scholar] [CrossRef]
  32. Ismail, K.M. Evaluation of cysteine as environmentally friendly corrosion inhibitor for copper in neutral and acidic chloride solutions. Electrochim. Acta 2007, 52, 7811–7819. [Google Scholar] [CrossRef]
  33. Singh, P.; Chauhan, D.S.; Chauhan, S.S.; Singh, G.; Quraishi, M.A. Chemically modified expired Dapsone drug as environmentally benign corrosion inhibitor for mild steel in sulphuric acid useful for industrial pickling process. J. Mol. Liq. 2019, 286, 110903. [Google Scholar] [CrossRef]
  34. Wang, J.; Wang, T.; Wu, Y. The inhibition effect and mechanism of L-cysteine on the corrosion of bronze covered with a CuCl patina. Corros. Sci. 2015, 97, 89–99. [Google Scholar] [CrossRef]
  35. Zhu, Y.; Sun, Q.; Wang, Y.; Tang, J.L.; Wang, Y.Y.; Wang, H. Molecular dynamic simulation and experimental investigation on the synergistic mechanism and synergistic effect of oleic acid imidazoline and l-cysteine corrosion inhibitors. Corros. Sci. 2021, 185, 109414. [Google Scholar] [CrossRef]
  36. Han, Z.F.; Huang, X.; Chen, J.C.; Chen, J.Y.; Zhou, H.R. Study on the compounding of cysteine modified Schiff base and decanoic acid as corrosion inhibitors for bronze with patina. Surf. Interfaces 2024, 46, 103996. [Google Scholar] [CrossRef]
  37. Hsissou, R.; Benhiba, F.; Dagdag, O.; Bouchti, M.E.; Nouneh, K.; Assouag, M.; Briche, S.; Zarrouk, A.; Elharfi, A. Development and potential performance of prepolymer in corrosion inhibition for carbon steel in 1.0 M HCl: Outlooks from experimental and computational investigations. J. Colloid. Interf. Sci. 2020, 574, 43–60. [Google Scholar] [CrossRef]
  38. Zhang, X.; He, Q.L.; Gu, H.B.; Colorado, H.A.; Wei, S.Y.; Guo, Z.H. Flame-Retardant Electrical Conductive Nanopolymers Based on Bisphenol F Epoxy Resin Reinforced with Nano Polyanilines. ACS Appl. Mater. Inter. 2013, 5, 898–910. [Google Scholar] [CrossRef]
  39. Liu, J.; Wang, S.; Peng, Y.; Zhu, J.; Zhao, W.; Liu, X. Advances in sustainable thermosetting resins: From renewable feedstock to high performance and recyclability. Prog. Polym. Sci. 2021, 113, 101353. [Google Scholar] [CrossRef]
  40. Gu, H.; Ma, C.; Gu, J.; Guo, J.; Yan, X.; Huang, J.; Zhang, Q.; Guo, Z. An overview of multifunctional epoxy nanocomposites. J. Mater. Chem. C 2016, 4, 5890–5906. [Google Scholar] [CrossRef]
  41. Diraki, A.; Omanovic, S. Smart PANI/epoxy anti-corrosive coating for protection of carbon steel in sea water. Prog. Org. Coat. 2022, 168, 106835. [Google Scholar] [CrossRef]
  42. Zhou, C.G.; Chen, Q.; Zhao, J.J.; Wang, S.H.; Li, J.Y.; Ai, L.Q.; Li, T.Z.; Hu, C.B. Superhydrophobic epoxy resin coating with composite nanostructures for metal protection. Mater. Today. Commun. 2024, 38, 107803. [Google Scholar] [CrossRef]
  43. Chen, Z.R.; Liu, X.H.; Chen, H.N.; Li, J.L.; Wang, X.F.; Zhu, J.F. Application of epoxy resin in cultural relics protection. Chin. Chem. Lett. 2024, 35, 109194. [Google Scholar] [CrossRef]
  44. Jerman, I.; Vuk, A.Š.; Koželj, M.; Orel, B.; Kovac, J. A Structural and Corrosion Study of Triethoxysilyl Functionalized POSS Coatings on AA 2024 Alloy. Langmuir 2008, 24, 5029–5037. [Google Scholar] [CrossRef] [PubMed]
  45. Liu, J.; Sue, H.J.; Thompson, Z.J.; Bates, F.S.; Dettloff, M.; Jacob, G.; Verghese, N.; Pham, H. Nanocavitation in Self-Assembled Amphiphilic Block Copolymer-Modified Epoxy. Macromolecules 2008, 41, 7616–7624. [Google Scholar] [CrossRef]
  46. Pang, V.; Thompson, Z.J.; Joly, G.D.; Francis, L.F.; Bates, F.S. Block Copolymer and Nanosilica-Modified Epoxy Nanocomposites. ACS Appl. Polym. Mater. 2021, 3, 4156–4167. [Google Scholar] [CrossRef]
  47. Briffa, S.M.; Vella, D.A. The behaviour of as-applied and artificially weathered silica–epoxy consolidants on a typical Mediterranean porous limestone: A comparison with TEOS. Herit. Sci. 2019, 7, 30. [Google Scholar] [CrossRef]
  48. Feng, L.; Li, S.; Li, Y.; Li, H.; Zhang, L.; Zhai, J.; Song, Y.; Liu, B.; Jiang, L.; Zhu, D. Super-Hydrophobic Surfaces: From Natural to Artificial. Adv. Mater. 2002, 14, 1857–1860. [Google Scholar] [CrossRef]
  49. Xiao, F.; Yuan, S.J.; Liang, B.; Li, G.Q.; Pehkonenc, S.O.; Zhang, T.J. Superhydrophobic CuO nanoneedle-covered copper surfaces for anticorrosion. J. Mater. Chem. A 2015, 3, 4374. [Google Scholar] [CrossRef]
  50. Ueda, E.; Levkin, P.A. Emerging Applications of Superhydrophilic-Superhydrophobic Micropatterns. Adv. Mater. 2013, 25, 1234–1247. [Google Scholar] [CrossRef]
  51. Yang, C.; Wang, C.Y.; Zhao, X.Z.; Shen, Z.; Wen, M.; Zhao, C.C.; Sheng, L.Y.; Wang, Y.G.; Xu, D.K.; Zheng, Y.F.; et al. Superhydrophobic surface on MAO-processed AZ31B alloy with zinc phosphate nanoflower arrays for excellent corrosion resistance in salt and acidic environments. Mater. Design. 2024, 239, 112769. [Google Scholar] [CrossRef]
  52. Fu, X.; He, X. Fabrication of super-hydrophobic surfaces on aluminum alloy substrates. Appl. Surf. Sci. 2008, 255, 1776–1781. [Google Scholar] [CrossRef]
  53. Zhang, X.; Shi, F.; Yu, X.; Liu, H.; Fu, Y.; Wang, Z.; Jiang, L.; Li, X. Polyelectrolyte multilayer as matrix for electrochemical deposition of gold clusters: Toward superhydrophobic surface. J. Am. Chem. Soc. 2004, 126, 3064. [Google Scholar] [CrossRef] [PubMed]
  54. Qian, B.T.; Shen, Z.Q. Fabrication of Superhydrophobic Surfaces by Dislocation-Selective Chemical Etching on Aluminum, Copper, and Zinc Substrates. Langmuir 2005, 21, 9007–9009. [Google Scholar] [CrossRef]
  55. Liu, X.; Jiang, B.Z.; Guo, Y.; Zhang, Z.; Ren, L. Fabrication of super-hydrophobic nano-sized copper films by electroless plating. Thin Solid Films 2010, 518, 3731–3734. [Google Scholar] [CrossRef]
  56. Yang, C.; Wang, Y.G.; Fu, H.Y.; Yang, S.N.; Zhu, Y.M.; Yue, H.R.; Jiang, W.; Liang, B. A stable eco-friendly superhydrophobic/superoleophilic copper mesh fabricated by one-step immersion for efficient oil/water separation. Surf. Coat. Tech. 2019, 359, 108–116. [Google Scholar] [CrossRef]
  57. Rao, A.V.; Latthe, S.S.; Mahadik, S.A.; Kappenstein, C. Mechanically stable and corrosion resistant superhydrophobic sol gel coatings on copper substrate. Appl. Surf. Sci. 2011, 257, 5772–5776. [Google Scholar] [CrossRef]
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Figure 1. Images of the corrosion of ancient Chinese bronze relics [5] (reprinted/adapted with permission from Elsevier, 1998). (a) pin, (b) bar, (c) sword, (d) bar, (e) razor blade, and (f) axe.
Figure 1. Images of the corrosion of ancient Chinese bronze relics [5] (reprinted/adapted with permission from Elsevier, 1998). (a) pin, (b) bar, (c) sword, (d) bar, (e) razor blade, and (f) axe.
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Figure 2. Annual publication quantity for research on the corrosion and protection of bronzeware, shown in a line chart.
Figure 2. Annual publication quantity for research on the corrosion and protection of bronzeware, shown in a line chart.
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Figure 3. Network visualization among different countries that have published at least 10 papers.
Figure 3. Network visualization among different countries that have published at least 10 papers.
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Figure 4. Network visualization among different keywords in bronze corrosion-related papers.
Figure 4. Network visualization among different keywords in bronze corrosion-related papers.
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Figure 5. Network visualization among the clusters of keywords in bronze corrosion-related papers.
Figure 5. Network visualization among the clusters of keywords in bronze corrosion-related papers.
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Figure 6. The layering situation of corrosion products on bronze relics [5] (reprinted/adapted with permission from Elsevier, 1998). (a) transversal section of a pit, bronze, (b) transversal section of a thick crust, bronze, (c) schematic representation of the structure, (d,e) details of the internal altered zone under the red cuprous oxide layer, (d) is a detail of (b) showing a thin disrupted cuprous chloride layer up to the internal zone where "ghost" structures of the alloy are still observed (e) shows a pit with intergranular corrosion.
Figure 6. The layering situation of corrosion products on bronze relics [5] (reprinted/adapted with permission from Elsevier, 1998). (a) transversal section of a pit, bronze, (b) transversal section of a thick crust, bronze, (c) schematic representation of the structure, (d,e) details of the internal altered zone under the red cuprous oxide layer, (d) is a detail of (b) showing a thin disrupted cuprous chloride layer up to the internal zone where "ghost" structures of the alloy are still observed (e) shows a pit with intergranular corrosion.
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Figure 7. An illustration of an EDXRF device.
Figure 7. An illustration of an EDXRF device.
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Figure 8. (a) The fluorescence reaction of an FD1 molecule under low pH. (b) Fluorescence emission of FD1 after adding HCl; Ultraviolet light photos of AA1052 alloy surface coated with 0.5 wt.% copolymerized with acrylate by the β-thiopropionate group (8-HQ) transparent epoxy coating exposed in 3.5 wt.% NaCl solution for (c) 2 days and (d) results 3 days later [12] (reprinted/adapted with permission from Elsevier, 2011).
Figure 8. (a) The fluorescence reaction of an FD1 molecule under low pH. (b) Fluorescence emission of FD1 after adding HCl; Ultraviolet light photos of AA1052 alloy surface coated with 0.5 wt.% copolymerized with acrylate by the β-thiopropionate group (8-HQ) transparent epoxy coating exposed in 3.5 wt.% NaCl solution for (c) 2 days and (d) results 3 days later [12] (reprinted/adapted with permission from Elsevier, 2011).
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Figure 9. The structural formulae and infrared spectra of CYS and CYB. (a) Structural formulae of reactants and products. (b) FT-IR [36]. (Reprinted/adapted with permission from Elsevier, 2024).
Figure 9. The structural formulae and infrared spectra of CYS and CYB. (a) Structural formulae of reactants and products. (b) FT-IR [36]. (Reprinted/adapted with permission from Elsevier, 2024).
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Figure 10. (a) Structure of POSS. (b) Schematic diagram of POSS modification. (c) SEM image of VE-1 (2%) and (d) VE-3 (5%). (e) σ-ε curve of VE composite materials. (f–h) Applications of corrosion protection on the surface of bronze relics [43]. (Reprinted/adapted with permission from Elsevier, 2024).
Figure 10. (a) Structure of POSS. (b) Schematic diagram of POSS modification. (c) SEM image of VE-1 (2%) and (d) VE-3 (5%). (e) σ-ε curve of VE composite materials. (f–h) Applications of corrosion protection on the surface of bronze relics [43]. (Reprinted/adapted with permission from Elsevier, 2024).
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Figure 11. Anti-corrosion diagram of superhydrophobic copper surface [49] (reprinted/adapted with permission from Royal Society of Chemistry, 2015).
Figure 11. Anti-corrosion diagram of superhydrophobic copper surface [49] (reprinted/adapted with permission from Royal Society of Chemistry, 2015).
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Zhang, L.; Yang, C.; Guo, Y. Corrosion and Protection of Chinese Bronze Relics: A Review. Coatings 2024, 14, 1196. https://doi.org/10.3390/coatings14091196

AMA Style

Zhang L, Yang C, Guo Y. Corrosion and Protection of Chinese Bronze Relics: A Review. Coatings. 2024; 14(9):1196. https://doi.org/10.3390/coatings14091196

Chicago/Turabian Style

Zhang, Lingling, Chao Yang, and Yingzhi Guo. 2024. "Corrosion and Protection of Chinese Bronze Relics: A Review" Coatings 14, no. 9: 1196. https://doi.org/10.3390/coatings14091196

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