Sharif Digital Repository

In this paper, an analysis is presented of some bronze vessels from recent excavations at the first millennium BC site of Sangtarashan in eastern Luristan, Iran, according to metallography (OM), ICP-OES and SEM-EDS methods to identify alloying as well as manufacturing processes. This study provides new evidence for a better understanding of the bronze archaeometallurgy during the Iron Age in Iran. It concludes that the artifacts contain homogenous and single phase tin bronze (Cu-Sn) alloy. The Sn content in the artifacts also allowed to apply mechanical operations on the vessels without causing brittleness. Apart from tin, other elements that are classified as trace elements were present,... 

The aim of this research is to obtain composite coatings of bronze (90% Cu-10% Sn) with graphite particles. The electrodeposition of G-Cu (Sn) composites from an alkaline bath containing cyanide is described. Composite coatings consisting of graphite particles and copper-tin were prepared by means of the conventional electrocodeposition (CECD) and sediment codeposition (SCD) techniques. The graphite particles involved were less than 10 μm. The dependence of graphite amount in the composite coatings was investigated in relation to the graphite concentration in bath, cathode current density, stir rate and technique type and it was shown that these parameters strongly affected the volume... 

Background: Archaeological metallic artefacts buried in soils deteriorate by means of various environmental as well as internal factors and mechanisms over time such as change in composition and microstructure of metal and corrosive factors due to long-term burial environment. Corrosion in metals occurs in different morphologies and results in different types of corrosion products based on soil composition. Identification of corrosion mechanisms and morphology in archaeological metals can help conservators to characterize deterioration occurred in metals and make decisions to protect artefacts about preventing further deterioration. In archaeological bronzes, different layers may form on the... 

The corrosion process of two iron dagger handles decorated with bronze strips found from the Ziviyeh area, which is one of the important Iron Age sites in the northwest of Iran, is thoroughly investigated. X-ray radiography was used to obtain the damages and corrosion zones of the artifact. Optical and scanning electron microscopies were used to study the microstructure of cross sections and to achieve structural details about the metal matrix and corrosion layers. The X-ray diffraction method was used to study the chemical characterization of corrosion products. The results of studies have shown that severe stress on bronze strips is caused by the formation of goethite and lepidocrocite... 

Design and operation of a double-fiber sensor for displacement measurements are reported in this study. In this arrangement, one fiber transmits the laser light to the target and the second one receives the light reflected off the target and transmits to a photodetector. Utilizing inexpensive plastic optical fibers offers advantages such as higher reflexability and more robustness at a reasonable cost, which are required for some applications. The novelties of the reported design are compactness of the fiber probe, flexibility, long dynamic range (22 mm), and it is possible to use the source and the detector at the same side. The displacement of the target causes the intensity modulation and... 

Archaeological excavations in western Iran have recently revealed a significant Luristan Bronzes collection from Sangtarashan archaeological site. The site and its bronze collection are dated to Iron Age II/III of western Iran (10th-7th century BC) according to archaeological research. Alloy composition, microstructure and manufacturing technique of some sheet metal vessels are determined to reveal metallurgical processes in western Iran in the first millennium BC. Experimental analyses were carried out using Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy and Optical Microscopy/Metallography methods. The results allowed reconstructing the manufacturing process of bronze... 

Microstructural characteristics and mechanical properties of a friction stir welded cast aluminum bronze (Cu-9Al-1Fe), produced by a sand casting method, have been investigated at tool rotation of 850-1500 rpm and traverse speed of 50-100 mm/min. Refinement of the primary coarse cast microstructure in the base metal was seen after friction stir welding. Microstructure of the stir zone was characterized in four distinct areas of non-isometric fine grains while a significant grain growth was noticed in some of the areas. Conditions of grain growth are defined with high heat input intensity and low heat transfer capability. The grain size was observed to decrease after FSW, resulting in a... 

The wear and friction properties of G-Cu (Sn) composite coatings containing different amounts of graphite particles were examined. The presence of graphite particles improved antifriction properties of composite coatings. The effects of graphite percent in composite coating, tin content of matrix, load, speed and distance on the coefficient of friction and wear resistance of bronze-graphite composite coatings were studied. The results of the present studies revealed that hardness, wear resistance, coefficient of friction are dependent on volume percentage of graphite in composite coating. It was shown that the composite coating containing approximately 5.4 (vol.%) graphite and matrix with... 

Composite coatings containing self-lubricant particles like graphite, MoS2, PTFE are extensively used to decrease the coefficient of friction of tribo-surfaces. The aim of this study is to investigate the effect of pulse electrodeposition parameters on particle codeposition process and characteristics of bronze-graphite composite coatings electrodeposited from cyanide-stannate bronze electroplating bath. Results showed a slight increase in tin content and a promising increase in hardness of bronze coating by a decrease in duty cycle at constant average current density. Both tin content of the coating and grain refinement seem to participate in hardness enhancement. By increasing the... 

This paper addresses the fabrication of bronze-nano-graphite coatings containing 30. nm sized graphite particles. Addition of Poly Vinyl Pyrrolidone (PVP) and dispersing the suspension by ultrasound was utilized to stabilize the electroplating solution. Pulsed current electrodeposition was used and the deposits were characterized in terms of graphite content, particle dispersion in coating and morphology. The wear behavior of the coating was compared to bronze-micro-graphite coatings prepared with the same experimental conditions. The present coating showed improved wear resistance in comparison to bronze-micro-graphite coatings at the same graphite content  

Cu-Sn composites incorporated with graphite and/or SiC particles were produced by electrodeposition technique. The effect of particle concentration in the plating bath and current density on tin content and volume percentage of particles in the coatings has been investigated. Structure, morphology, micro hardness and wear properties of the coatings have been studied. The results showed that particles cause an increase of tin content in the plated Cu-Sn. Graphite and silicon carbide particles had different effects on coating hardness; 7.8. vol.% graphite decreased the hardness of Cu-Sn layer from 231. Hv to 172. Hv whereas, 5.1. vol.% SiC raised the hardness to 316. Hv. Moreover, friction... 

A pyrophosphate based solution, as an acidic electrolyte, was developed for bronze electroplating. By using a statistical experimental design, response surface method, the effects of five factors [copper concentration (Cu), tin concentration (Sn), pyrophosphate concentration (P), current density j and pH] on the composition of the electroplated alloy as well as the process efficiency were evaluated. Statistical analysis indicated that all the parameters were significant and a second order polynomial model was successfully fitted to the data for both the alloy composition and the process efficiency. Based on the results obtained, a solution of Cu(II)8.04 g L -1, Sn(II)=26.36 g L -1, P=113.22... 

The recently study of the corrosion in some bronze artefacts from the Sangtarashan Iron Age site, western Iran, was established to identify corrosion morphology and mechanism in these objects. The corrosion layers in 22 samples were studied by optical microscopy, scanning electron microscopy–energy-dispersive X-ray spectroscopy and X-ray diffraction methods. The results showed that a thin corrosion crust has formed on the surface of bronzes with a triple-layer structure, including two internal and one external corrosion layers. The formation of these layers is due to copper leaching from the bronze surface. The internal corrosion part has been a compact, tin-rich corrosion/oxidation product...