青铜病：考古铜基钱币保护的主要挑战

腐蚀反应是博物馆室内环境、室外大气、埋土等各种环境中影响金属遗产的主要危害现象。硬币是具有内在价值的小物体，包含与当时的建筑、文化和艺术相关的信息。

Corrosion is a major threat to metal artifacts in various environments, including museums, outdoor atmosphere, and burial soil. Coins, being small objects with intrinsic value, hold rich information about architecture, culture, and arts of their time. They often bear images of rulers, national or religious symbols, and inscriptions, offering insights into the political and economic history of their period. Many coins show important buildings, temples, and other architectural marvels, serving as small canvases for the artistic styles of their period. The study of coins combines elements of history, archaeology, and art history.

腐蚀是各种环境中金属文物的主要威胁，包括博物馆、室外大气和埋土。钱币是具有内在价值的小物件，蕴藏着有关当时建筑、文化和艺术的丰富信息。它们通常带有统治者的图像、国家或宗教象征以及铭文，让人们深入了解该时期的政治和经济历史。许多硬币都描绘了重要的建筑物、寺庙和其他建筑奇迹，充当了当时艺术风格的小画布。对硬币的研究结合了历史、考古学和艺术史的元素。

Bronze represents a class of alloys widely used in ancient times, valued for its hardness and greater corrosion-resistant compared to pure metals. Ancient cast bronze typically contains copper with varying amounts of tin, and zinc depending on the desired properties of the alloy. The addition of lead (Pb) improved the fluidity of molten bronze, making it a preferred material for production of decorative coins, particularly during the Greco-Roman ages. The corrosion products of bronze are mainly composed of copper oxides, forming a uniform pale brown to black-brown layer known as the primary patina. Preserving this patina especially the cuprite, along with surface details, is the main goal in the conservation of copper-based coins.

青铜代表了古代广泛使用的一类合金，与纯金属相比，因其硬度和更高的耐腐蚀性而受到重视。古代铸造青铜通常含有铜以及不同含量的锡和锌，具体取决于合金的所需性能。添加铅 (Pb) 改善了熔融青铜的流动性，使其成为生产装饰硬币的首选材料，特别是在希腊罗马时代。青铜的腐蚀产物主要由铜氧化物组成，形成均匀的浅棕色至黑棕色层，称为初生铜绿。保护铜锈（尤其是赤铜矿）以及表面细节是保护铜基硬币的主要目标。

Patina is a thin, natural or artificial layer that forms on bronze due to chemical reactions such as oxidation. It develops over time through exposure to environmental factors, including humidity, pollution, and soil. Patinas are composed of compounds such as copper oxides (e.g., cuprite), carbonates (e.g., malachite), or sulfates. Natural patinas provide protection against corrosion, while artificial patinas are applied for aesthetic or protective purpose. In archaeology, patinas are valuable as they act as a historical record and serve as a protective barrier, making their preservation crucial in conservation efforts.

铜绿是由于氧化等化学反应而在青铜上形成的一层薄薄的天然或人造层。它随着时间的推移通过暴露于环境因素（包括湿度、污染和土壤）而发展。铜锈由铜氧化物（例如赤铜矿）、碳酸盐（例如孔雀石）或硫酸盐等化合物组成。天然铜绿可提供防腐蚀保护，而人造铜绿则用于美观或保护目的。在考古学中，铜绿很有价值，因为它们可以作为历史记录并充当保护屏障，使其保存对于保护工作至关重要。

Surface degradation occurs due to corrosion, which involves not only oxidation but also the formation of copper chlorides (bronze disease) and other corrosion products that vary in thickness and composition. Bronze disease is an active corrosion process in which bronze reacts with chloride ions to form cuprous chloride (CuCl), leading to metal degradation. In humid environments, cuprous chloride reacts with water to produce hydrochloric acid, further accelerating deterioration. This results in pitting and flaking, weakening the structural integrity of artifacts. Bronze disease can compromise the structural, historical, and aesthetic values of archaeological coins. The reaction speed on the bronze surface varies depending on the object’s history and surrounding environment.

表面退化是由于腐蚀而发生的，腐蚀不仅涉及氧化，还涉及氯化铜（青铜病）和其他厚度和成分不同的腐蚀产物的形成。青铜病是一种活跃的腐蚀过程，其中青铜与氯离子反应形成氯化亚铜 (CuCl)，导致金属降解。在潮湿的环境中，氯化亚铜与水反应生成盐酸，进一步加速变质。这会导致凹坑和剥落，削弱文物的结构完整性。青铜病会损害考古钱币的结构、历史和美学价值。青铜表面的反应速度根据物体的历史和周围环境而变化。

Sulfur and chloride ions can penetrate the patina and metal core, causing pits to form on the surface. Aggressive chloride accelerates the dissolution of copper-based alloys, causing the loss of native protective layers in burial environments. The corrosion layers mainly consist of malachite (CuCO3. Cu(OH)2), which disrupts the CuCl/Cu2O mixture and causes exfoliation. Post-excavation cuprous chloride (CuCl) hydrolyzes into hydroxyl chloride polymorphs Cu2OH3Cl in the presence of water. Bronze disease occurs with the formation polymorphous copper hydroxyl chlorides, including atacamite, paratacamite, clinoatacamite, and botallackite.

硫和氯离子可以渗透铜锈和金属芯，导致表面形成凹坑。侵蚀性氯化物会加速铜基合金的溶解，导致埋藏环境中天然保护层的丧失。腐蚀层主要由孔雀石 (CuCO3.Cu(OH)2) 组成，它会破坏 CuCl/Cu2O 混合物并导致剥落。开挖后的氯化亚铜 (CuCl) 在水存在下水解成羟基氯化物多晶型物 Cu2OH3Cl。青铜病随着多晶型羟基氯化铜的形成而发生，包括氯铜矿、副氯铜矿、斜氯铜矿和斜氯铜矿。

Lead plays an effective role in influencing the corrosion rate by forming highly stable lead carbonates and insoluble lead chloride, which remain stable after excavation. Protective conservation is the most effective process to prevent or at least delay degradation. However, achieving suitable environmental conditions is challenging, making it necessary to apply a protective system. Protective coatings, including natural patinas or applied treatments, inhibit corrosion by forming a barrier against moisture, oxygen, and pollutants, helping to preserve the artifact and minimize further damage. The coating system is a significant topic to stop corrosion and ensure the long-term stability of archaeological coins. There is a continuous study to provide better protection for objects by preventing the influence of humidity and contaminations with special requirements for conservation-restoration ethics such as ease of application, transparency, good appearance, long-term stability, reversibility, and safety for conservators-restorers and the environment.

铅通过形成高度稳定的碳酸铅和不溶性氯化铅，在挖掘后保持稳定，从而有效地影响腐蚀速率。保护性保存是防止或至少延缓退化的最有效过程。然而，实现合适的环境条件具有挑战性，因此有必要应用保护系统。保护性涂层，包括天然铜锈或应用处理，通过形成防潮、氧气和污染物的屏障来抑制腐蚀，有助于保护文物并最大限度地减少进一步的损坏。涂层系统是防止腐蚀并确保考古钱币长期稳定的重要课题。人们不断进行研究，通过防止湿度和污染的影响来为物品提供更好的保护，并满足保护修复伦理的特殊要求，例如易于使用、透明度、良好​​的外观、长期稳定性、可逆性和保护者的安全性。修复者和环境。

Through ancient conservation, natural resins were used to coat metal surfaces, but they often curled and flaked away. In contrast, methyl acrylate/ ethyl methacrylate 30:70% (Paraloid B-72®) is considered the most widely used coating for archaeological objects in Egypt due to its economic efficiency, transparency, and reversibility. It can be applied on both clean metal surfaces and those covered with patina.

通过古代的保护，天然树脂被用来涂覆金属表面，但它们经常卷曲和剥落。相比之下，丙烯酸甲酯/甲基丙烯酸乙酯 30:70% (Paraloid B-72®) 因其经济效率、透明度和可逆性而被认为是埃及考古文物中使用最广泛的涂层。它可以应用于干净的金属表面和覆盖有铜绿的表面。

The study of archeological coins is essential for both the preservation of cultural heritage and advancements in corrosion science. Analyzing the corrosion products of bronze archeological coins provides insights into the surface morphology, which aids in the preservation of cultural heritage.

考古硬币的研究对于文化遗产的保护和腐蚀科学的进步至关重要。分析青铜考古钱币的腐蚀产物可以深入了解其表面形态，有助于保护文化遗产。