Bronze Samples Research Articles

Analysis of Thermal Isotropy of Parallelepiped Shape of Bronze Samples for Mechanical Engineering Applications

Objective: The need to find out whether the specimens are ‘thermally thin’ or not is the basis for applying the law of conservation of energy or the Fourier differential equation of heat conduction in finding the time dependence of the specimen temperature. The aim of this study is to find out the thermal field distribution in a parallelepiped shaped bronze specimen and to verify the Bio number. Methods: A number of external variables make it difficult to maintain a monotonic change in sample temperature during the ‘heating’ stage. These factors led to the use of the cooling method to study tiny samples with low inertia of the thermal process. We used the cooling method to experimentally verify the isotropy of the thermal field in the sample and to study the kinetics of cooling relative to the sample axes over a wide range of temperatures. Results: It was found out that in natural air cooling the main mechanisms are conductive, convective and radiative heat transfer. The contribution of thermal radiation to the cooling process is noticeable at high temperatures. It was found that the typical cooling time increases with sequential radiative, conductive and convective heat transfer. By extending the temperature study area to, for the first time, we were able to observe each component of the heat transfer process independently. The values of the typical cooling time on all axes correspond to the experimental error bounds. It was found that the temperature value of the sample is independent of the coordinates and depends only on time. In this case, the law of conservation of energy can be used to explain the dependence of body temperature on cooling time. Conclusion: It is shown that the sample under study is ‘thermally thin’, i.e. the thermal field is constant in all directions. In this situation, the thermal balance equation should be applied rather than the Fourier differential equation of heat conduction, since the temperature gradient inside the body is practically zero. The results obtained are of great importance for the study of cooling processes of metallic products in thermal power engineering, heat engineering and thermophysics.

FOUNDRY TRIBOTECHNICAL BRONZE BrO3A3 CORROSION RESISTANCE INVESTIGATION

Problem statement. Bronzes have been and remain the main material for friction bearings, anti-friction and corrosion-resistant parts manufacturing that work under high loads, chemically active aggression influence at low and elevated temperatures, in cavitation, erosion, etc. conditions. That is, technology continuous development requires from anti-friction bronzes constant their corrosion resistance increasing, as a factor that will allow to significantly expand their application scope and increase cast products from them durability and reliability. The purpose of the articles. Based on relationship between corrosion damages and chemical composition analysis, compare BrO3A3 bronze corrosion resistance with BrA5, BrA9Zh3L and BrO5Tz5C5 bronzes corrosion resistance as the materials most often used in industry for parts manufacturing that work in friction nodes and chemically active environments. Methodology. Alloys for samples production have been prepared by technical purity primary charge materials fusing. Melting has been carried out in induction crucible furnace using a graphite crucible and charcoal as a coating material. Cast bronze samples corrosion resistance studies have been carried out in accordance with ISO 7384:2001, ISO 11845:1995 and GOST 9.308-85 requirements. Studied samples corrosion resistance has been evaluated based on the results of their relative weight loss during exposure for 90 days in climate chamber at relative humidity of 93 ± 3 % and temperature of 40 ± 2 °С, in sea and fresh water with temperature of 20...22 °С. Conclusions. BrO3A3 bronze, among the studied foundry bronzes, is characterized by the best level of anti-corrosion properties in all environments used in this research. In this regard, it is a reason to recommend the studied bronze for tribotechnical purpose cast parts manufacturing, which work in air, fresh or sea water.

Casting and Forging techniques Found in Bronze vessels Excavated from Mangduksa Temple Site in Gyeongju

Metallographic analysis of microstructure, chemical composition and hardness was carried out on 7 bronze vessels from Mangduksa temple site in Gyeongju. Result show that the technology of bronze vessels divided into casting and forging followed by quenching. Tin contents of casting bronzes were around 11∼14 wt%, forging bronzes were about 21∼23 wt% tin. Kundika and dish of casting bronzes were Cu-Sn-Pb alloys and 5 bowl samples were produced using Cu-Sn binary alloy materials. These show that the manufacturing technology was applied different depends on the Sn contents. Also 4 bowls of approximately 20 wt% tin were manufactured by forging and quenching at above 520℃ avoid formation of the brittle δ phase. The non-metallic inclusions in the 7 bronze samples are divided into Cu-S and Cu-Fe-S-Se systems, indicating that the copper ore used the production is different. It was confirmed that casting bronze vessels had lower micro-hardness values than forging samples, and that hardness values changed depending on Sn content and processing.

Study of initial corrosion and protection behavior of bronze from the Western Zhou Dynasty assisted by BTA

Electrochemistry methods and surface characteristics were used to investigate the corrosion behaviors in the initial stage and the inhibition efficiency of BTA in simulated soil environments for simulated bronze samples. The results show that the inhibition efficiency can reach 99.96 %; A protrusion morphology of corrosion products formed by PbSO4 with a channel formed by Cu compounds that can transport corrosive media was found in the cross-section of the Pb-rich samples. A mechanism for galvanic corrosion was proposed with the assistance of the inhibition effect of BTA, which can explain the different corrosion behaviors of samples with different Pb contents.

Understanding the passivation layer formed by tolyltriazole on copper, bronze, and brass surfaces

Tolyltriazole (TTAH) is used industrially as a corrosion inhibitor for copper alloys, particularly in organic media. In this study, the morphology and chemistry of the layer formed by TTAH on copper and copper alloys under realistic conditions is investigated, with focus on the effects due to the presence of tin or zinc in the substrates. A combination of X-ray photoelectron spectroscopy (XPS), medium energy ion scattering (MEIS), and scanning transmission electron microscopy (STEM) has been used. It was found that an inhomogeneous metal–organic layer forms on the surface of copper specimens, likely in the form of copper nanoparticles surrounded by CuxTTAy complexes. This layer increases in thickness for at least 30 days. Chemically, the copper species in the layer are initially in the +2 oxidation state, but after longer exposure to TTAH, mostly Cu(I) is observed. In bronze samples, tin does not appear to segregate to the surface layer. In brass samples, zinc is depleted from the bulk and forms a thicker ZnxTTAy layer.

Effect of Tin Addition on the Mechanical Properties and Microstructure of Aluminium Bronze Alloyed with 4% Nickel

The current study investigates the impact of adding tin to aluminium bronze alloyed with 4% nickel on its microstructure and mechanical properties. Sand casting was chosen as the most cost-effective and efficient method of preparing the aluminium bronze alloy. Following their melting points, six distinct samples of aluminium bronze alloyed with 0% to 10% tin were added into the crucible furnace. Nickel with the highest melting point of 1453°C was added into the crucible furnace first, while tin with the lowest melting of 231.9°C was added last into the crucible furnace. The alloying components were mixed well by manually mixing the liquid for around five minutes. After sand casting, the specimens were machined, sectioned, and grounded then tests were carried out to measure their hardness, tensile strength, and impact resistance. The results of the tests indicate that the tensile strength first increases and subsequently declines as the tin addition increases. The hardness of the aluminium bronze alloy increases as the proportion of tin addition increases. The results of the investigations also demonstrate that as the hardness of the specimens increases, their impact resistance decreases and the tensile stress of each specimen increases with strain.

Characterization, surface preparation, conservation, and corrosion protection of bronze arrow heads from Cairo military museum using nanocomposite coating

The study focused on examining approximately 32 arrowheads from Cairo’s Qala Salah al-Din military museum, which showed significant signs of deterioration. The main objectives were to investigate the bronze alloy composition of these arrowheads and analyze the physical and chemical characteristics of their patinas. Understanding the causes and mechanisms of corrosion was crucial for developing effective conservation strategies to halt further degradation and identifying the corrosion products and metals involved. To achieve these goals, extensive examinations and analyses were conducted, including metallographic microscopy, SEM–EDS, and X-ray diffraction analysis to scrutinize the chemical composition, metallurgical features, and corrosion products of the bronze samples. Additionally, experimental studies were carried out to determine the most suitable protective coating for preventing future corrosion. Various combinations of ZnO nanoparticles with Paraloid® 48 or Paraloid® 66 coatings were tested on simulated arrowheads, and electrochemical techniques such as EIS and RP were employed for measurement. The results indicated that combining ZnO nanoparticles with either Paraloid® 48 or Paraloid® 66 coatings resulted in lower corrosion rates compared to using each coating alone. Based on these findings, chemical cleaning with ZnO nanoparticles and Paraloid® 48 was selected for treatment to protect the arrowheads' surfaces. Overall, this study provides valuable insights into preservation techniques for these historically significant artifacts.

INVESTIGATION OF THE MACHINING PERFORMANCE OF ALUMINUM–BRONZE ALLOY IN WEDM USING TAGUCHI METHOD

Aluminum–Bronze alloys (Al-10%–Cu-balance) are difficult-to-machine cut alloys. Copper (Cu) metal itself is not suitable for machining. The machining performance of the Aluminum–Bronze alloy sample was investigated by the Wire Electric Discharge Machining (WEDM) method, which is among the non-traditional manufacturing methods used in conductive materials that are difficult to process. The aluminum–bronze sample with a diameter of 20[Formula: see text]mm was cut with 0.18[Formula: see text]mm molybdenum wire electrode. Table feedrate, pulse-on-time and pulse-space were used as experimental parameters. Surface roughness and energy consumption values were measured in WEDM process. According to Taguchi analysis and ANOVA results, it was determined that the pulse-on-time parameter was effective on the surface roughness and the table feedrate parameter was effective on the energy consumption.

The role of corrosion pit topography on stress concentration

Smooth semi-ellipsoids are typically used to simulate the effect of corrosion pits on stress, however, this does not account for pit geometry. Three corrosion pits were identified on Nickel Aluminium Bronze samples. These were scanned and converted to finite element models. The linear elastic stress concentration factor (Kt) of the corrosion pit FE models was 1.32–1.65 times larger than for an equivalent smooth semi-ellipsoid. This suggests that detailed consideration of pit geometry is needed to calculate accurate values of Kt and the assumption of a semi-ellipsoidal pit may not be conservative for fatigue lifetime predictions of pitted components.

Effect of heat treatment on mechanical properties and the structure of the tin-free aluminum bronze

Nowadays bronze products have quite high demand, for example, bronze liners, bushings, flanges, etc. Bronze is a rather malleable antifriction material with good corrosion resistance. Depending on the different methods of melting and processing bronze, it is possible to increase strength properties and reduce cost of production of bronze products. There are various types of tin-free bronze, such as aluminum, lead, beryllium, manganese, magnesium, chromium, zirconium, cadmium, silicon, bronze. In this article, cast tin-free bronzes produced by two casting methods, such as casting in a casting mold and casting on gasifiable models (CGM), are considered. The advantages and disadvantages of each method are analyzed. Experimental regimes of heat treatment during CGM were developed and tested. The tests of mechanical characteristics are carried out on prototypes and a full-fledged liner that is used in the nodes of a spindle device. The microstructure of samples during CGM before and after heat treatment is studied. Dependence of time resistance, relative, elongation, hardness and impact toughness on various heat treatment modes was studied. A general comparative analysis of mechanical properties depending on the method of melting and processing of bronze samples was also carried out. The economic calculation was carried out, which revealed the economic effect of CGM with further heat treatment. The heat treatment regimes have been developed, which make it possible to use the CGM casting method for inserts with obtaining mechanical properties at the level of casting into the mold according to GOST 493‒79.

Effect of heat treatment on mechanical properties and the structure of the tin-free aluminum bronze

Nowadays bronze products have quite high demand, for example, bronze liners, bushings, flanges, etc. Bronze is a rather malleable antifriction material with good corrosion resistance. Depending on the different methods of melting and processing bronze, it is possible to increase strength properties and reduce cost of production of bronze products. There are various types of tin-free bronze, such as aluminum, lead, beryllium, manganese, magnesium, chromium, zirconium, cadmium, silicon, bronze. In this article, cast tin-free bronzes produced by two casting methods, such as casting in a casting mold and casting on gasifiable models (CGM), are considered. The advantages and disadvantages of each method are analyzed. Experimental regimes of heat treatment during CGM were developed and tested. The tests of mechanical characteristics are carried out on prototypes and a full-fledged liner that is used in the nodes of a spindle device. The microstructure of samples during CGM before and after heat treatment is studied. Dependence of time resistance, relative, elongation, hardness and impact toughness on various heat treatment modes was studied. A general comparative analysis of mechanical properties depending on the method of melting and processing of bronze samples was also carried out. The economic calculation was carried out, which revealed the economic effect of CGM with further heat treatment. The heat treatment regimes have been developed, which make it possible to use the CGM casting method for inserts with obtaining mechanical properties at the level of casting into the mold according to GOST 493‒79

Chemical and physical studies of metallic alloy-based old Indian coins with LIBS coupled with multivariate analysis

The present work aims to demonstrate the capabilities of Laser-induced Breakdown Spectroscopy (LIBS) coupled with a multivariate technique for rapid quantification and classification of old Indian coins made of various alloys. Thirteen old Indian coins in different years of circulation, (1922–1986) were selected for the study. The concentrations were determined by Calibration free LIBS (CF-LIBS) method. The concentration of cuprum (Cu) is negligible, and aluminum (Al) is maximum in the first five coins, and vice-versa in the remaining eight coins. Two different multivariate methods, Principal Component Analysis (PCA) and Soft Independent Modelling of Class Analogy (SIMCA) have been used to classify and identify the coins. PCA classified all thirteen samples into four main alloy categories. The discernment of unknown samples to their probable class membership of alloy was performed using SIMCA. The surface hardness (Brinell hardness number) is linearly correlated with the plasma temperature and LIBS intensity ratios. The sample surface of the first and fifth coin belongs to Al-alloy, having the least surface hardness, and it became harder for Cu–Ni alloy, Ni-brass alloy, and bronze alloy. The hardness of the surface is more for bronze sample twelve. It is also observed that the plasma temperature increases monotonically with the Brinell hardness number. This analysis provides valuable information on fabrication methodology and explains large diversification in the elementary composition of old coins.

Influence of quenching medium on the dendrite morphology, hardness, and tribological behaviour of cast Cu–Ni–Sn spinodal alloy for defence application

Cu–Ni–Sn spinodal alloys (Spinodal bronze) are potential materials with robust applications in components associated with defence applications like bearings, propellers, bushes, and shafts of heavily loaded aircraft, off-road vehicles, and warships. This paper presents a comparative study using water, Brine solution, and SAE 40 oil as the quenching media in regular bronze (Cu–6Sn) and spinodal bronze (Cu–9Ni–6Sn) alloys. Morphological analysis was conducted by optical microscopy, transmission electron microscopy (TEM), and X-ray diffraction technique (XRD) on bronze and spinodal bronze samples immersed in the three different quenching media to understand the grain size and hardness values better. Tribological analysis was performed to analyze the effect of quenching media on the wear aspects of bronze and spinodal bronze samples. The hardness value of the brine-aged spinodal bronze samples was as high as 320 Hv, and the grain size was very low in the range of 60 μm. A quantitative comparison between brine-aged regular bronze and brine-aged spinodal bronze showed that the hardness (Hv) was almost 80% higher for brine-aged spinodal bronze. Further, the grain size was approximately 30% finer for spinodal bronze when compared with regular bronze. When the load was increased in spinodal bronze samples, there was an initial dip in wear rate followed by a marginal increase. There was a steady increase in friction coefficient with a rise in load for brine-aged regular bronze and spinodal bronze samples. These results indicate that brine solution is the most effective quenching medium for cast Cu–Ni–Sn spinodal alloys.

The novel paste electrolyte measuring cell for EIS testing of the commonly used surface protection on bronze

The cell was tested on polished and patinated bronzes of different compositions, on sulfide patina/Paraloid B-72-coated bronzes with different numbers of coating layers, on protected bronze samples with different degrees of damage to the protective layers, and on uncoated and coated patinated bronzes after 24 h conditioning in the condensation chamber. A quantitative criterion of Phase Angle at 0.1 Hz was deduced and explained. The systems show two or three time constants, depending on the number and integrity of the layers. Capacitances of the high-frequency response that are attributed to the coating range from 1.8 to 31 nF/cm2 and capacitances of the medium-frequency response attributed to the patina range from 1.1 F/cm2 to 2.3 nF/cm2, indicating Paraloid B-72 penetration into the pores of the patina. Log ∣Z∣ at 0.1 Hz decreases with mechanical damage to the protective layers. Damage also leads to the occurrence of the low-frequency response attributed to the Faradaic process on the substrate. The three layers of Paraloid B-72 on the sulfide patina had Log ∣Z∣ at 0.1 Hz around 8 and were insensitive to the 24-h condensation, indicating good protection. The cell was further applied to different sides of bronze coins, so no electrical contact with the substrate was required. The Kramers-Kronig test was applied to confirm the validity of the EIS results.

CORROSION AND PROTECTION OF NON-PATINATED, SULPHIDE- AND CHLORIDE-PATINATED BRONZE

The surface of bronze undergoes changes when it is exposed to a polluted atmosphere, and bronze should therefore be protected from this natural deterioration. The most common protective coating currently in use is Incralac, which includes toxic components and is reported to dissolve a few months after application. This work therefore investigates a fluoropolymer-based coating (FA-MS), and compares it to the protection offered by Incralac. Bronze samples (non-patinated, sulphide-patinated or chloride-patinated) were exposed to simulated urban rain for four months. The corrosion products formed were characterised using SEM/EDS and Raman analyses. To study the protection efficiency of the newly developed fluoropolymer coating (FA-MS) and Incralac protection, various electrochemical methods were used: measurements of open circuit potential linear polarisation and potentiodynamic measurements. Findings show that the FA-MS coating provides a protection efficiency of 71 % for chloride-patinated bronze and 99.5 % for sulphide-patinated bronze. Contact angles of the FA-MS samples were higher than those of the unprotected samples or the samples protected by Incralac, indicating better hydrophobic properties of the FA-MS coating.

Numerical Simulation of the Upsetting of Bronze Samples with Allowance for Changes in Their Relative Density

Numerical Simulation of the Upsetting of Bronze Samples with Allowance for Changes in Their Relative Density

Spectroscopic and Morphologic Investigation of Bronze Disease: Performance Evaluation of Portable Devices

Copper alloy artworks are particularly subjected to chloride attack, which may trigger bronze disease. Therefore, early identification of the phenomenon is crucial in order to stabilize the reactive copper chloride (CuCl) and remove the harmful corrosion products (atacamite and polymorphs). Confocal Raman Microspectroscopy (CRM) has proven to be effective for the detection of small amounts of atacamite, ascribable to the initial phases of corrosion. The handling of bronze artworks is often difficult or even impossible given their large size and weight, and sampling is not always allowed, making the use of portable instruments mandatory for on-site diagnostics. This paper proposes a method for the early detection of corrosion using non-invasive approaches. In this work, we present the results obtained from a set of artificially aged bronze samples with a suite of either laboratory (bench-top) or field (portable/transportable) instruments with the aim of highlighting their characteristics and performances in the diagnosis of bronze disease. Raman spectroscopy, Fiber Optics Reflectance Spectroscopy (FORS), Optical Coherence Tomography (OCT), and Scanning Electron Microscopy (SEM) were applied for chemical and morphological characterization of the samples.

Microstructure, Chemistry and Mineralogy Approach for the Diagnostics of Metallic Finds of the Tomba della Biga (Adria, Italy)

This work is focused on the characterization of metallic finds that are part of an ancient war biga from the Tomba della Biga, using different approaches for the diagnostics and also the conservation of this important cultural heritage. The materials analyzed were brought to light in the necropolis of Canal Bianco (Adria, Italy). The samples were analyzed using Optical Reflected Light Microscopy (ORLM), Scanning Electron Microscopy (SEM) and micro-Raman Spectroscopy (µ-RS). The results highlighted the occurrence of two different alloys (Fe and Cu-Sn-bronze) showing important structural and textural variations. These results, along with µ-RS, gave details on the surface and subsurface morphology, as well as the microstructures and the chemical and mineralogical composition of the finds. In particular, µ-RS highlighted the presence of magnetite and goethite as the main mineralogical phases for Fe-samples and malachite, azurite and Cu-oxide for bronze samples. In addition, an attempt was made to trace the manufacturing process, the purity of the alloys and the degree of slagging. Results of analytical studies show corrosion products of the samples which could be evidence of metallurgical aspects. The good state of conservation due to favorable conditions in the burial environment preserved the metal finds from intense corrosion, supporting the hypothesis that the samples reached equilibrium with soil during their life in the burial environment. This proposed methodology based on the microstructure, chemistry and mineral microanalysis allows the diagnostic and evaluation of the state of conservation of metallic finds.

Analysis of Several Physical Phenomena Measured on the Metallic Materials Cut by Abrasive Water Jets (AWJ).

Cutting using an abrasive water jet is a complex process involving several physical phenomena. This research studies some of them, mostly the influence of selected variables on the measured forces and vibrations. The traverse speed represents one of the key parameters when cutting using the AWJ. In the presented research, a set of experiments was performed on twelve different metal samples, while the force sensor measured the exerted forces and accelerometers measured the vibrations. Ten different types of steel samples of the same dimensions were cut applying five different traverse speeds. The data obtained during these measurements show that an increase in the traverse speed leads to an increase in the measured forces and vibrations. An analogous experiment performed on bronze and duralumin samples of the same dimensions, having applied higher speeds to compensate for the difference in the material structure and properties, completes the presented data. The most important results of the research are that exerted forces in the z-axis are higher than those in the x-axis, whereas measured vibrations are higher in the x-axis. According to our research, the elemental structure, especially the carbide formation, affects the measured forces and vibrations substantially.

ABOUT THE ARROWHEADS WITH “SIDE SPIKES”IN THE RANGE OF WEAPONS OF THE NORTH CAUCASUS POPULATION
 IN THE SECOND HALF OF THE 2d – EARLY 1st MIL. BC

The article examines the issue of emergence and development of the tradition of using bone and bronze arrowheads with the so-called "side spike" by the population of the Central and North-Eastern Caucasus. For this purpose, materials from household and funerary monuments are used. It was determined that initially arrowheads with the blades lowered down ("stingers») appeared on the territory of Transcaucasia at the end of the second millennium BC. The materials collected by the author demonstrate that during that period arrowheads with one or two additional side "spikes" on the handle were found exclusively on the territory of the North Caucasus. They were originally made of bone. Such findings are recorded on the territory of Dagestan. Later, this type of weapons was also manifested in individual samples of bronze in the form of so-called "flat arrowheads", the starting point of which has been territory of Transcaucasia. This type of arrowhead did not become popular among the population who lived in the Central and North-Eastern Caucasus. Later, the side spike was widely used only at the early stage of the "Scythian" period, initially on the two-bladed, and then on the three- and four-bladed arrowheads. However, the very idea of this type of weapons has initially appeared among the Caucasian tribes since the era of the developed Bronze Age, and maintained till the beginning of the first third of the first thousand BC.