Research

13 pages, 3872 KiB

Open AccessArticle

Study on the Bronze Weapons Excavated from Xichuan, China

by Shengwei Zhao, Xin Liu, Zhen Chen, Siyu Zhang, Qing Niu and Xing Zhao

Metals 2024, 14(4), 395; https://doi.org/10.3390/met14040395 - 28 Mar 2024

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The collection of twelve bronze artifacts discovered in Xichuan provides invaluable historical insights into the Warring States period (476 BC to 221 BC) of ancient China. To investigate their fabrication techniques and current state of preservation, a comprehensive analysis was conducted using a [...] Read more.

The collection of twelve bronze artifacts discovered in Xichuan provides invaluable historical insights into the Warring States period (476 BC to 221 BC) of ancient China. To investigate their fabrication techniques and current state of preservation, a comprehensive analysis was conducted using a metallographic microscope, a scanning electron microscope, and an electron spectrometer to examine the microstructure and elemental composition of the artifacts. The findings revealed that the copper content in these bronze artifacts varied between 41.82% and 87.95%, the tin content ranged from 6.79% to 46.88%, and the lead content was less than 28.96%. The microstructure exhibited an α-solid-solution dendritic-crystal-segregation structure, with a substantial amount of (α + δ) eutectic distributed in an island-like pattern. Lead was dispersed unevenly, appearing as small granules and large ellipsoids. The composition of these weapons aligned with their intended use, adhering to the manufacturing standards of traditional Chinese bronzes. However, their state of preservation was suboptimal, necessitating immediate protective measures. This study contributes physical evidence to the research on early Chinese bronze production and offers scientific guidance for the conservation and restoration of these bronze artifacts. Full article

(This article belongs to the Special Issue Metals for Art and Cultural Heritage)

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18 pages, 6719 KiB

Open AccessArticle

Exploring the Manufacturing Process of a Renaissance Breach Pike

by Paolomarco Merico, Michela Faccoli, Roberto Gotti and Giovanna Cornacchia

Metals 2024, 14(1), 41; https://doi.org/10.3390/met14010041 - 29 Dec 2023

Viewed by 668

Abstract

An archaeometallurgical study of a Renaissance breach pike was performed to elucidate its manufacturing process. Optical microscopy observations and microhardness measurements indicated that the breach pike was forged starting from a heterogeneous steel lump. The microstructural features were compatible with post-forging air cooling. [...] Read more.

An archaeometallurgical study of a Renaissance breach pike was performed to elucidate its manufacturing process. Optical microscopy observations and microhardness measurements indicated that the breach pike was forged starting from a heterogeneous steel lump. The microstructural features were compatible with post-forging air cooling. The chemistry of a large set of nonmetallic inclusions was investigated by scanning electron microscopy coupled with X-ray dispersive spectroscopy. Compositional data were analyzed by multivariate statistics to distinguish smelting-related slag inclusions. A logistic regression model indicated that the steel was probably produced by the direct method. The liquidus temperatures of the slag inclusions indicated maximum smelting temperatures in the range of 1200 °C to 1300 °C. A thermodynamic-based model was adopted to estimate the average smelting conditions in terms of temperature and oxygen chemical potential and investigate the disequilibrium of slag inclusion–metal systems. For low-disequilibrium systems, the computed temperature values range between 1095 °C and 1118 °C, while the oxygen chemical potentials (μ_O2) span from −442 to −374 kJ/mol. Full article

(This article belongs to the Special Issue Metals for Art and Cultural Heritage)

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17 pages, 17806 KiB

Open AccessArticle

Corrosion Behaviors of Outdoor Bronze Sculptures in an Urban–Industrial Environment: Corrosion Experiment on Artificial Sulfide Patina

by Heehong Kwon and Namchul Cho

Metals 2023, 13(6), 1101; https://doi.org/10.3390/met13061101 - 11 Jun 2023

Cited by 2 | Viewed by 1549

Abstract

Copper alloys interact with air pollutants to form corrosion products and, consequently, a patina on outdoor bronze sculptures. In this study, corrosion experiments were conducted to clarify the corrosion behaviors of artificial sulfide patina in an urban–industrial environment on a quaternary bronze alloy [...] Read more.

Copper alloys interact with air pollutants to form corrosion products and, consequently, a patina on outdoor bronze sculptures. In this study, corrosion experiments were conducted to clarify the corrosion behaviors of artificial sulfide patina in an urban–industrial environment on a quaternary bronze alloy (Cu–Zn–Sn–Pb) with a composition and metallurgical properties similar to those of outdoor bronze sculptures. The correlation between the chromaticity and reflectance of the patina revealed increasing brochantite with the corrosion of the patina and an association between the chromaticity a^* and patina growth. Cuprite and brochantite were distinguished, and the point at which brochantite covered the patina surface was determined. The quantitative changes in brochantite were mainly influenced by physical causes such as the crystal size and patina layer thickness as well as by Cu²⁺ ions working as color formation ions moving to the outermost layer. Atmospheric corrosion of the alloy resulted in reduced Cu and Zn contents and increased Sn and Pb contents. The patina consisted of brochantite in the outermost layer and cuprite and cassiterite in the inner layers. These findings should clarify corrosion characteristics such as the surface color, composition, and changes in corrosion products of outdoor bronze sculptures and contribute toward their preservation. Full article

(This article belongs to the Special Issue Metals for Art and Cultural Heritage)

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15 pages, 12479 KiB

Open AccessArticle

Archaeometallurgical Characterization of Two Lombard Early Medieval Bloomery Slags from Ponte di Val Gabbia I Site (Northern Italy)

by Paolomarco Merico, Michela Faccoli, Daniele La Corte and Giovanna Cornacchia

Metals 2023, 13(5), 984; https://doi.org/10.3390/met13050984 - 19 May 2023

Viewed by 1131

Abstract

An archaeometallurgical characterization of two iron smelting tap slags recovered from the early medieval site of Ponte di Val Gabbia I (Brescia, northern Italy) was performed. The main goal was to infer from the slags the working conditions of the ancient bloomery furnace [...] Read more.

An archaeometallurgical characterization of two iron smelting tap slags recovered from the early medieval site of Ponte di Val Gabbia I (Brescia, northern Italy) was performed. The main goal was to infer from the slags the working conditions of the ancient bloomery furnace in terms of temperature and oxygen chemical potential. The petrology of both slags was investigated by light optical microscopy and scanning electron microscopy, while their chemical compositions were measured via scanning electron microscopy coupled with X-ray dispersive spectroscopy. High-resolution Raman micro-spectrometry was used to confirm the identification of the mineralogical phases. The software Rhyolite-MELTS was used to compute the liquidus temperatures of the two slags, which were found to be 1120 °C and 1146 °C. These temperatures approximate the working temperature of the bloomery furnace. A thermodynamic-based approach was adopted to estimate the redox conditions of the reducing atmosphere of the smelting furnace, revealing that the two slags formed in different redox environments. Specifically, the resulting oxygen chemical potentials were −382.61 kJ/mol and −243.80 kJ/mol at the liquidus temperatures of 1120 °C and 1146 °C, respectively. Full article

(This article belongs to the Special Issue Metals for Art and Cultural Heritage)

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19 pages, 6819 KiB

Open AccessArticle

Analysis of Lead Smelting Technology in the Early Bronze Age Based on Smelting Slag from the Central Plains of China

by Shuoyang Li, Yanxiang Li, Rong Zhu and Hongyang Wang

Metals 2023, 13(2), 435; https://doi.org/10.3390/met13020435 - 20 Feb 2023

Cited by 2 | Viewed by 1919

Abstract

To explore the source of Pb in Bronze Age artefacts from the Central Plains (Zhongyuan) in China, we investigated non-ferrous minerals from the Qingyuan archaeological site in Yuanqu County near the Zhongtiao Mountains. Fragments of smelting slag from the Erlitou cultural layer were [...] Read more.

To explore the source of Pb in Bronze Age artefacts from the Central Plains (Zhongyuan) in China, we investigated non-ferrous minerals from the Qingyuan archaeological site in Yuanqu County near the Zhongtiao Mountains. Fragments of smelting slag from the Erlitou cultural layer were collected. The smelting slag was investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and lead isotope analysis. The SEM and EDS results confirmed that the slag contained Pb, Pb–As, and Cu–Pb–Sn inclusions and non-metal impurities such as low-Zn spinels. The XRD results signified that the bulk of the slag comprised Fe–Mn–Si phases. The chemical state of Pb was mainly Pb–O with some metallic Pb, as identified by XPS. The theoretical melting point was calculated using FactSage7.1 based on the composition and phase characterisation. The calculated temperature was 1100–1200 °C, which agreed well with the actual melting point of 1114–1354 °C. The slag composition and inclusion phases indicated that Pb–Zn–O ores with Mn and As were added during reduction smelting in Qingyuan. The raw materials of smelting included crude Pb with minor amounts of Cu, As, and Sn. Lead isotope analysis revealed that the lead materials produced in Qingyuan were likely transferred to Yanshi City in the Shang Dynasty. The findings of this study provide significant clues for exploring lead mineral production in the Central Plains during the Early Bronze Age. Full article

(This article belongs to the Special Issue Metals for Art and Cultural Heritage)

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32 pages, 14434 KiB

Open AccessArticle

Analysis of the First Metallic Works That Represented a Geometric Innovation in Their Architectural Application: The Origin of the Architecture-Engineering Dichotomy

by Adela Rueda Márquez de la Plata and Pablo Alejandro Cruz Franco

Metals 2023, 13(1), 32; https://doi.org/10.3390/met13010032 - 23 Dec 2022

Viewed by 1637

Abstract

This research analyses the geometric modifications and improvements that the application of the technique of metallurgy meant for architecture. In the early days of engineering and without having the historical burden that architecture bore, the small variations in the classical definition of geometry [...] Read more.

This research analyses the geometric modifications and improvements that the application of the technique of metallurgy meant for architecture. In the early days of engineering and without having the historical burden that architecture bore, the small variations in the classical definition of geometry meant the greatest advances at a structural and conceptual level in the world of metal structures. The use of metal as a structural element capable of containing new uses and responding to the great challenges that progress required was definitive for the development of the new architecture and paradigms of the new century. The new metallic materials and their mathematical and constructive models were the cause and effect of what would be the basis of the great change in modern architecture and engineering and would lay the foundations of today’s world. The interaction of these two new disciplines, architecture and engineering, and their relationship with metal is the basis of this research, which aims to find out where, when, and how these geometric changes took place that started to change the conception of metal structures. Full article

(This article belongs to the Special Issue Metals for Art and Cultural Heritage)

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18 pages, 4333 KiB

Open AccessFeature PaperArticle

Evolution and Evaluation of Aesthetic Properties in Weathering Steel Accelerated Patinas: The Role of Lepidocrocite

by Ana Crespo, Gloria Pérez, José A. Jiménez, Irene Llorente, Sagrario Martínez-Ramírez, Emilio Cano and Iván Díaz

Metals 2022, 12(6), 977; https://doi.org/10.3390/met12060977 - 07 Jun 2022

Viewed by 1715

Abstract

Weathering steels are widely used in civil engineering, architecture and contemporary art due to their mechanical properties, their enhanced resistance to atmospheric corrosion as well as their aesthetic properties. Artists and blacksmiths often apply chemical treatments to obtain the appealing colors of a [...] Read more.

Weathering steels are widely used in civil engineering, architecture and contemporary art due to their mechanical properties, their enhanced resistance to atmospheric corrosion as well as their aesthetic properties. Artists and blacksmiths often apply chemical treatments to obtain the appealing colors of a patina in a shorter period of time. However, the development of an accelerated patina may have an effect on the final appearance and color of the surface. With the aim of evaluating differences in color and studying the evolution of the surface, eight accelerated patinas were made and exposed to the atmosphere for periods of time of up to 24 months and were compared to a natural patina. The characterization studies showed the presence of lepidocrocite on the surface. A close inspection of the X-ray diffraction patterns showed the displacement of the (020) lepidocrocite reflection and asymmetric broadening of selective lines of this phase that were associated to stacking and twins faults, respectively. These faults decrease with the exposure time and are related to a maximum at 630 nm in the reflectance spectrum and the stabilization of the b* coordinate (yellow color). The colors of the accelerated patinas differ from the natural patina at short exposure times. However, they tend to converge at longer exposure times. Full article

(This article belongs to the Special Issue Metals for Art and Cultural Heritage)

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12 pages, 14822 KiB

Open AccessArticle

Corrosion Behavior of Ancient White Cast Iron Artifacts from Marine Excavations at Atmospheric Condition

by Pei Hu, Minghao Jia, Mohan Li, Jian Sun, Yong Cui, Dongbo Hu and Gang Hu

Metals 2022, 12(6), 921; https://doi.org/10.3390/met12060921 - 27 May 2022

Cited by 4 | Viewed by 2250

Abstract

A large number of iron pot artifacts were excavated from the “Nanhai I” shipwreck. The rapid embrittlement and pulverization of these objects (that have a good matrix) in the atmospheric environment is worthy of attention. Metallographic analysis showed that the material of the [...] Read more.

A large number of iron pot artifacts were excavated from the “Nanhai I” shipwreck. The rapid embrittlement and pulverization of these objects (that have a good matrix) in the atmospheric environment is worthy of attention. Metallographic analysis showed that the material of the iron pots was hypereutectic white cast iron. Micro-CT observations revealed that there were numerous microcracks and fissures within the seemingly well-preserved iron. These fissures increased and enlarged with prolonged exposure to air. Scanning electron microscopy exhibited that the microcracks were initially created at the “concave surface” formed by the ferrite corrosion, and the cementite was gradually torn by the local accumulation of large internal stresses. Micro-Raman proved that the structure of rust was varied and complex during the generation and development of fissures. The dimension of corrosion products could expand and contract in mutual transformation, forming local internal stress and promoting the expansion of microcracks. This work proposed a reasonable mechanism for the rapid embrittlement and pulverization in the atmospheric environment of such hypereutectic white cast iron artifacts out of the sea, which provided a scientific reference for future protection. Full article

(This article belongs to the Special Issue Metals for Art and Cultural Heritage)

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16 pages, 6032 KiB

Open AccessFeature PaperArticle

Corrosion Inhibition and Rust Conversion of Catechin on Archaeological Iron of Nanhai I

by Minghao Jia, Pei Hu, Zisang Gong, Jian Sun, Yong Cui, Dongbo Hu and Gang Hu

Metals 2022, 12(5), 714; https://doi.org/10.3390/met12050714 - 22 Apr 2022

Cited by 6 | Viewed by 2095

Abstract

This work took the iron objects from the Nanhai No. 1 shipwreck in the Southern Song Dynasty of China as the sample to test and analyze the application potential of catechin, an environmentally friendly corrosion inhibitor and rust converter. The article used metallographic [...] Read more.

This work took the iron objects from the Nanhai No. 1 shipwreck in the Southern Song Dynasty of China as the sample to test and analyze the application potential of catechin, an environmentally friendly corrosion inhibitor and rust converter. The article used metallographic microscopy to clarify that the structure of the iron artifact was hypereutectic white iron. By means of micro-Raman, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), potentiodynamic polarization and electrochemical impedance spectroscopy, catechin had the ability to react with iron oxyhydroxides such as goethite, akaganeite and lepidocrocite in the rust, forming an amorphous substance with a marked signal about 1380 cm⁻¹ as phenolic-Fe in infrared properties. The new products could make the original rust layer form a laminated dense structure. After the archaeological iron was soaked in 3.0 g/L catechin, the corrosion current density decreased by 37.13% and the corrosion potential shifted positively by 32.67 mV. The anode reaction was more inhibited than the cathode in the polarization curve. The rust resistance in electrochemical impedance increased to 3.75 times and the ion diffusion resistance increased to 6.33 times. The corrosion inhibition efficiency was 21.75% and the rust conversion efficiency was 73.26%. After 36 h of accelerated corrosion, the protection effect of the newly transformed rust layer was still better than that of the original state. Catechin was a mild protection material which showed satisfactory performance for archaeological iron and has a good application prospect. Full article

(This article belongs to the Special Issue Metals for Art and Cultural Heritage)

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