Dana Ashkenazi fields of research interest include materials characterization, materials processing, metallurgy, additive manufacturing, and archaeometallurgy.
Thirteen Late Roman copper alloy coins with a dark concretion layer from the Early Islamic period... more Thirteen Late Roman copper alloy coins with a dark concretion layer from the Early Islamic period Ma‘agan Mikhael B shipwreck were chosen to undergo an experimental chemical cleaning and polishing procedure for removing the concretion while limiting the damage to the surviving metal. These coins, and two more without concretion discovered on the beach nearby, were then subjected to a series of non-destructive analyses–visual testing, XRF, multi-focal light microscopy, and Raman spectroscopy–to determine their state of preservation, identify their corrosion products, and acquire information regarding their core material. An additional coin was examined by destructive metallographic light microscopy and SEM-EDS analyses to gain further information concerning the concretion cover. Preservation varied: For some chemically cleaned coins, a shiny orange-coloured metallic surface was exposed, while others were poorly preserved. Moreover, evidence of the stamping process was also observed. ...
Silver coins were the first coins to be manufactured by mass production in the southern Levant. A... more Silver coins were the first coins to be manufactured by mass production in the southern Levant. An assemblage of tiny provincial silver coins of the local (Judahite standard) and (Attic) obol-based denominations from the Persian and Hellenistic period Yehud and dated to the second half of the fourth century BCE were analyzed to determine their material composition. Of the 50 silver coins, 32 are defined as Type 5 (Athena/Owl) of the Persian period Yehud series (ca. 350–333 BCE); 9 are Type 16 (Persian king wearing a jagged crown/Falcon in flight) (ca. 350–333); 3 are Type 24 series (Portrait/Falcon) of the Macedonian period (ca. 333–306 BCE); and 6 are Type 31 (Portrait/Falcon) (ca. 306–302/1 BCE). The coins underwent visual testing, multi-focal light microscope observation, XRF analysis, and SEM-EDS analysis. The metallurgical findings revealed that all the coins from the Type 5, 16, 24, and 31 series are made of high-purity silver with a small percentage of copper. Based on these ...
The Akko Tower Wreck is the remains of a 25-m-long merchant brig dated to the first half of the 1... more The Akko Tower Wreck is the remains of a 25-m-long merchant brig dated to the first half of the 19th century. During the underwater excavations, 105 brass nails were retrieved from the shipwreck. The nails were divided into two groups based on their microstructure: Type A nails were characterized by Wid-manst€ atten plates, while Type B nails by a dendritic microstructure. In each group there were miscellaneous nails, distinguished by their different shapes. Ten miscellaneous nails were characterized by XRF, light microscopy, SEM-EDS analysis, microhardness measurements, anisotropy of magnetic susceptibility examination, and lead isotope analysis. The brass nails were post-cementation products manufactured by casting. The microstructure combined with the AMS analysis, indicated that Type A nails were of better quality than Type B ones. The lead isotope analysis of the nails suggested that their raw material most likely originated in Great Britain.
Journal of Mining and Metallurgy, Section B: Metallurgy, 2018
The Akko Tower Wreck is ently the remains of a 25-m-long merchant brig, dated to the first half o... more The Akko Tower Wreck is ently the remains of a 25-m-long merchant brig, dated to the first half of the nineteenth century. During the 2015 underwater excavation, a piece of brass sheet was retrieved from the shipwreck and its surface and bulk were examined by metallurgical analyses. The examinations revealed a unique example of almost two hundred years? natural etching, which took place in the sea underwater environment. The surface of the sheet was covered with different copper and zinc oxides, which were identified by XRD analysis. Observation of the naturally etched surface with multi-focal light microscopy and SEM-EDS analysis indicated a microstructure of annealed ?-brass, similar to that of its bulk. S-OES chemical analysis of the bulk revealed a composition of 65.0 wt% Cu, 34.4 wt% Zn and 0.6 wt% Pb. Based on the thickness of the sheet and its good state of preservation, it is suggested that it was used as sheathing to protect the hull against marine organisms, and to improve...
This paper studies the effect of a plasma column ejected from solid titanium by localized microwa... more This paper studies the effect of a plasma column ejected from solid titanium by localized microwaves in an ambient air atmosphere. Nanoparticles of titanium dioxide (titania) are found to be directly synthesized in this plasma column maintained by the microwave energy in the cavity. The process is initiated by a hotspot induced by localized microwaves, which melts the titanium substrate locally. The molten hotspot emits ionized titanium vapors continuously into the stable plasma column, which may last for more than a minute duration. The characterization of the dusty plasma obtained is performed in-situ by small-angle X-ray scattering (SAXS), optical spectroscopy, and microwave reflection analyses. The deposited titania nanoparticles are structurally and morphologically analyzed by ex-situ optical and scanning-electron microscope observations, and also by X-ray diffraction. Using the Boltzmann plot method combined with the SAXS results, the electron temperature and density in the du...
An Aramaic-inscribed object made of copper-alloy was discovered in 1993 in the south-western part... more An Aramaic-inscribed object made of copper-alloy was discovered in 1993 in the south-western part of Tulûl Mas‘ud (Moshav Elyakhin) and has recently been studied using an archaeometallurgical approach. Based on visual testing and multifocal light microscopy observation, the object was probably produced in a nearby workshop, with the inscription engraved using a sharp tool during the production process. Given the larger assemblage of inscribed copper-alloy artefacts from the site, this item appears not only to have been used as a cultic object, but was also most probably made for the purpose of cultic offerings. The XRF analysis results of the Aramaic-inscribed object after it was sanded revealed the core metal to have been made of relatively pure copper with a tin content of less than 1.0 wt. % Sn. The choice to produce the object using a low-tin copper-alloy indicates that the alloy was chosen based on technological considerations, in order to facilitate plasticity in fashioning th...
Fragments of wall paintings retrieved from Hellenistic Tell Iẓṭabba (Nysa-Scythopolis), an archae... more Fragments of wall paintings retrieved from Hellenistic Tell Iẓṭabba (Nysa-Scythopolis), an archaeological site located in the area of the Beth She'an Valley (Israel), are the subject of this study. This research aims to characterize the plaster and color pigments of wall paintings retrieved from the site in order to gain new information concerning their nature, their origin and the technologies that were used to paint the walls of a Hellenistic settlement in the Near East. For that purpose, visual testing inspection, XRF, SEM-EDS, and XRD analyses were applied combined with archaeological and geographical data. As the site was founded in the<br> 160s BCE and destructed in 108/07 BCE, the material analyzed is not only stratigraphically well-secured but also well-dated to the mid-second century BCE. The walls of the dwellings under discussion were painted by the fresco method and the white-hued plaster was made of calcium carbonate matrix with embedded aggregates. The red an...
A discovery of the use of small metal plates was recently made at the Frankish sites of ‘Atlit, A... more A discovery of the use of small metal plates was recently made at the Frankish sites of ‘Atlit, Arsur and Acre. These plates were used in the masonry, and we suggest for the first time their identification as construction implements that we term “spacers”. At Arsur, due to the homogenous use of relatively small ashlars to maintain level courses of finely built masonry walls, the spacers were found integrated into both interior and exterior walls. These spacers, dated to the second quarter of the thirteenth century, were subjected to metallurgical characterization. Some were made of copper-alloy, probably cast on site and having undergone surface finishing; while the others were corroded ferrous spacers, revealing a heterogeneous microstructure and too were probably produced on site. The present findings contribute to a better understanding of the construction method of stone masonry at Arsur Castle, enabling a deeper insight into a particular building technology.
Fragments of decorated floor tiles were retrieved from the Akko Tower shipwreck, Israel. Most til... more Fragments of decorated floor tiles were retrieved from the Akko Tower shipwreck, Israel. Most tiles were made of bright brown fired clay with a white glaze decorated with colored stenciled motifs (Type A); and others consisted of a red-brown fired clay body, coated with a brown pigment covered with transparent brown glaze (Type B). This study aimed to characterize the two tile types; to reveal information concerning the manufacturing process; and to determine the origin of their raw material. A multidisciplinary approach was used, including light microscopy, SEM-EDS, electron probe microanalysis with wavelength-dispersive X-ray spectroscopy (EPMA-WDS), XRD, Raman spectroscopy, and time-of-flight secondary ion mass spectrometry (TOF-SIMS) analyses. The characterization of both tile types demonstrated the use of different raw materials. The Type A tiles were covered with tin-opacified majolica glaze and colored with various mixtures of pigments. The blue color was due to pigment rich ...
This novel research aims to examine the macro and microstructural bonding region development duri... more This novel research aims to examine the macro and microstructural bonding region development during magnetic pulse welding (MPW) of dissimilar additive manufactured (AM) laser powder-bed fusion (L-PBF) AlSi10Mg rod and AA6060-T6 wrought tube, using both optimal- and high-energy welding conditions. For that purpose, various joint characterisation methods were applied. It is demonstrated that high-quality hermetic welds are achievable with adjusted MPW process parameters. The macroscale analysis has shown that the joint interfaces are deformed to a waveform shape; the interface is starting relatively planar, with waves forming and growing in the welding direction. The observed thickening of the flyer’s wall after welding is the result of its diametral inward deformation, taking place during the process. A slight increase in microhardness was adjacent to the faying interfaces; a higher increase was measured on the AlSi10Mg material side, while a smaller one was observed on the AA6060 s...
Laser powder-bed fusion (LPBF) method is one of the most important additive manufacturing (AM) te... more Laser powder-bed fusion (LPBF) method is one of the most important additive manufacturing (AM) technologies. AM-LPBF parts frequently need post-printing coatings for electrical and thermal conductivity enhancement, or matching decoration considerations. The current study presents a methodology for surface finishing of AM-LPBF AlSi10Mg artifacts coated with electroless gold. For this purpose, gold was deposited on AM-LPBF AlSi10Mg disk-shaped specimens and coins, resulting in an appearance similar to the original objects. The gold coating was characterized as a function of deposition time and gold film thickness. Mass and dimension measurements, optical profilometry, light microscopy observation, XRD analysis and a FIB-SEM technique were applied to characterize the coated samples. The roughness of the plated specimens was slightly reduced as the thickness of the gold film was increased. AM-LPBF AlSi10Mg disk-shaped specimens were coated successfully for the first time by electroless gold plating technique. The developed surface finish technique can be used for various applications, including 3D-printed replicas of ancient prestige artifacts and coins for museum exhibitions.
In the 2016 excavation season of the Akko Tower shipwreck, a ferrous stud-link anchor chain and a... more In the 2016 excavation season of the Akko Tower shipwreck, a ferrous stud-link anchor chain and a rod, both covered with thick encrustation and concretion, were retrieved from the site. The chain links, studs, and rod were analyzed by metallurgical methods, including: radiographic testing, x-ray fluorescence, light microscopy, scanning electron microscopy with energy-dispersive spectroscopy, optical emission spectroscopy, and microhardness measurements, in order to determine their composition and microstructure. The links and the rod were made of wrought iron, while the studs were made of gray cast iron with a significant silicon content of 2 wt.%. The welding zone of the links was identified. The chain was end-welded by forge welding, and the stud was fixed mechanically. The design and manufacturing characteristics of the chain are typical of nineteenth century stud-link anchor chain, which supports the dating of the ship. It is suggested that the chain served the secondary anchor of the ship.
Metals and their alloys were used by ancient civilizations based on their appearance and properti... more Metals and their alloys were used by ancient civilizations based on their appearance and properties. During antiquity, the production process of metal artifacts frequently caused strain hardening, cracking, and loss of strength. In addition, devastating failure has often occurred after long burial periods, resulting from residual stresses and continuous corrosion attack. Therefore, the present study aims to examine how a fracture mechanics approach, integrated with failure analysis tools, may assist archeologists in gaining additional information concerning ancient metal objects. For this purpose, a literature survey of postmortem studies of the RMS Titanic ship's failure is presented, followed by a review of various archeological and historical studies of metal objects and structures made of silver, lead, copper, iron, and their alloys. Lastly, based on the current literature review, a methodology is proposed for analyzing ancient metal artifacts. This approach may assist archeologists in gaining a better understanding of the manufacturing techniques of ancient metal objects, their original shape and dimensions, the cause of failure, and state of preservation and conservation. Moreover, the use of such an approach may be valuable for future conservation and restoration of such archeological metal artifacts.
Annals of Dunarea de Jos University of Galati Fascicle XII Welding Equipment and Technology, 2019
Fused Deposition Modelling (FDM) is one of the most important Additive Manufacturing (AM) technol... more Fused Deposition Modelling (FDM) is one of the most important Additive Manufacturing (AM) technologies. This is a technology suitable for various engineering applications and currently used with many types of thermoplastic materials including Acrylonitrile Butadiene Styrene (ABS). AM-FDM printed ABS possesses an inherent capacity for property modifications as a function of printing parameters. The main goal of the present ongoing research project is to estimate the strength of the AM-FDM printed ABS for varying printing process parameters. In the present study, the mechanical and structural characterizations of AM-FDM ABS were evaluated by light microscopy and mechanical testing. Three-point bend flexural test results revealed the mechanical properties as well as the fracture behaviour according to the dimensions and printing strategies of the build-on specimens. An innovative transmitted-light microscopy experimental method was developed and utilized to investigate the crack propagation behaviour under bending.
The Akko 1 shipwreck is the remains of a 26-metre-long Egyptian armed vessel or auxiliary naval b... more The Akko 1 shipwreck is the remains of a 26-metre-long Egyptian armed vessel or auxiliary naval brig built at the beginning of the 19th century. Remains of six flintlock muskets were retrieved from the shipwreck, and characterised by various metallurgical methods. The research aimed to study the composition and microstructure of the musket fittings and their manufacturing processes, and if possible, to determine the date and origin of the raw materials. The lead isotope analysis of the fittings suggests that their raw material originated in Great Britain. Based on their typology and composition, the fittings were made in Great Britain of brass alloy and manufactured by casting, probably at the same workshop; and the staple was manufactured by casting and drawing. Considering the zinc content, combined with the manufacturing techniques, the fittings were manufactured between the latter part of the 18th and the early 19th centuries, which might indicate that they were purchased in the course of 19th century weapons trade to be used on board the Egyptian ship.
After three excavation seasons the Ma'agan Mikhael B shipwreck has revealed, among other objects,... more After three excavation seasons the Ma'agan Mikhael B shipwreck has revealed, among other objects, seven coins. The coins were found covered with a black concretion layer, which was carefully removed from five of them. Metallurgical methods were used in order to reveal the composition, microstructure, and manufacturing process of the coins and to determine their date and the origin of the raw material. The coins were made of cast copper-lead alloy and were heated before being stamped. Based on the portrait of the House of Constantine I found on coins 120.1 and 120.2, and the figure on coin 120.5, combined with the composition of the coins, they were dated to the fourth century AD, when high concentrations of lead were added to alloys, most probably due to economic constraints. The study of the coins does not identify the ship's origin or her ports-of-call, since coins were essentially mobile.
Seven coins, covered with black concretion coating, found in the Byzantine-period Ma'agan Mikhael... more Seven coins, covered with black concretion coating, found in the Byzantine-period Ma'agan Mikhael B shipwreck, were examined in this study. Metallurgical methods comprising visual testing, XRF, multi-focal light microscopy, SEM-EDS analysis and Raman spectroscopy, were used to determine the corrosion products and microstructure of the coins. The analysis results show that the coins were made of copper-lead alloy with a heterogeneous microstructure of bright and dark metal areas. The external surfaces of the coins were mostly composed of oxides and corrosion product compounds rich in Cu, Pb and Sn, while the external dark concretion coating was rich in Si, S, Ca and C compounds. Gradual variation of the composition and structure of the oxides and concretion coating layers was observed.
A selection of fourth century BCE silver jewelry, which is part of the Samaria and Nablus Hoards,... more A selection of fourth century BCE silver jewelry, which is part of the Samaria and Nablus Hoards, was studied using nondestructive and minimally destructive analyses. A metallurgical methodology was applied and improved, based on the composition of the joints and bulk of the objects. The results indicate that most of the analyzed jewelry is made of silver containing a small percentage of copper, with higher Cu concentrations presented in the brazing and contact melting joints. The manufacturing processes of the jewelry from both hoards involved similar processes, including casting, hammering, bending, cutting, twisting, decorating by plastic deformation, granulating, and three joining methods. These techniques demonstrate that the artifacts were created by trained silversmiths. Our study provides better understanding of the technological skills in the late Persian-period province of Samaria and has implications regarding the production of local silver coins produced in the southern Levant.
Highlights An approach to teaching additive manufacturing (AM) course for engineering students ... more Highlights An approach to teaching additive manufacturing (AM) course for engineering students is suggested. A pedagogical model was developed, based on PDL strategy, for a 14-week AM course. The students designed and 3D printed devices helping people with disabilities. The projects served as useful collaborative learning experiences for AM education. The course demonstrates the potential of AM technologies as innovative environment.
Thirteen Late Roman copper alloy coins with a dark concretion layer from the Early Islamic period... more Thirteen Late Roman copper alloy coins with a dark concretion layer from the Early Islamic period Ma‘agan Mikhael B shipwreck were chosen to undergo an experimental chemical cleaning and polishing procedure for removing the concretion while limiting the damage to the surviving metal. These coins, and two more without concretion discovered on the beach nearby, were then subjected to a series of non-destructive analyses–visual testing, XRF, multi-focal light microscopy, and Raman spectroscopy–to determine their state of preservation, identify their corrosion products, and acquire information regarding their core material. An additional coin was examined by destructive metallographic light microscopy and SEM-EDS analyses to gain further information concerning the concretion cover. Preservation varied: For some chemically cleaned coins, a shiny orange-coloured metallic surface was exposed, while others were poorly preserved. Moreover, evidence of the stamping process was also observed. ...
Silver coins were the first coins to be manufactured by mass production in the southern Levant. A... more Silver coins were the first coins to be manufactured by mass production in the southern Levant. An assemblage of tiny provincial silver coins of the local (Judahite standard) and (Attic) obol-based denominations from the Persian and Hellenistic period Yehud and dated to the second half of the fourth century BCE were analyzed to determine their material composition. Of the 50 silver coins, 32 are defined as Type 5 (Athena/Owl) of the Persian period Yehud series (ca. 350–333 BCE); 9 are Type 16 (Persian king wearing a jagged crown/Falcon in flight) (ca. 350–333); 3 are Type 24 series (Portrait/Falcon) of the Macedonian period (ca. 333–306 BCE); and 6 are Type 31 (Portrait/Falcon) (ca. 306–302/1 BCE). The coins underwent visual testing, multi-focal light microscope observation, XRF analysis, and SEM-EDS analysis. The metallurgical findings revealed that all the coins from the Type 5, 16, 24, and 31 series are made of high-purity silver with a small percentage of copper. Based on these ...
The Akko Tower Wreck is the remains of a 25-m-long merchant brig dated to the first half of the 1... more The Akko Tower Wreck is the remains of a 25-m-long merchant brig dated to the first half of the 19th century. During the underwater excavations, 105 brass nails were retrieved from the shipwreck. The nails were divided into two groups based on their microstructure: Type A nails were characterized by Wid-manst€ atten plates, while Type B nails by a dendritic microstructure. In each group there were miscellaneous nails, distinguished by their different shapes. Ten miscellaneous nails were characterized by XRF, light microscopy, SEM-EDS analysis, microhardness measurements, anisotropy of magnetic susceptibility examination, and lead isotope analysis. The brass nails were post-cementation products manufactured by casting. The microstructure combined with the AMS analysis, indicated that Type A nails were of better quality than Type B ones. The lead isotope analysis of the nails suggested that their raw material most likely originated in Great Britain.
Journal of Mining and Metallurgy, Section B: Metallurgy, 2018
The Akko Tower Wreck is ently the remains of a 25-m-long merchant brig, dated to the first half o... more The Akko Tower Wreck is ently the remains of a 25-m-long merchant brig, dated to the first half of the nineteenth century. During the 2015 underwater excavation, a piece of brass sheet was retrieved from the shipwreck and its surface and bulk were examined by metallurgical analyses. The examinations revealed a unique example of almost two hundred years? natural etching, which took place in the sea underwater environment. The surface of the sheet was covered with different copper and zinc oxides, which were identified by XRD analysis. Observation of the naturally etched surface with multi-focal light microscopy and SEM-EDS analysis indicated a microstructure of annealed ?-brass, similar to that of its bulk. S-OES chemical analysis of the bulk revealed a composition of 65.0 wt% Cu, 34.4 wt% Zn and 0.6 wt% Pb. Based on the thickness of the sheet and its good state of preservation, it is suggested that it was used as sheathing to protect the hull against marine organisms, and to improve...
This paper studies the effect of a plasma column ejected from solid titanium by localized microwa... more This paper studies the effect of a plasma column ejected from solid titanium by localized microwaves in an ambient air atmosphere. Nanoparticles of titanium dioxide (titania) are found to be directly synthesized in this plasma column maintained by the microwave energy in the cavity. The process is initiated by a hotspot induced by localized microwaves, which melts the titanium substrate locally. The molten hotspot emits ionized titanium vapors continuously into the stable plasma column, which may last for more than a minute duration. The characterization of the dusty plasma obtained is performed in-situ by small-angle X-ray scattering (SAXS), optical spectroscopy, and microwave reflection analyses. The deposited titania nanoparticles are structurally and morphologically analyzed by ex-situ optical and scanning-electron microscope observations, and also by X-ray diffraction. Using the Boltzmann plot method combined with the SAXS results, the electron temperature and density in the du...
An Aramaic-inscribed object made of copper-alloy was discovered in 1993 in the south-western part... more An Aramaic-inscribed object made of copper-alloy was discovered in 1993 in the south-western part of Tulûl Mas‘ud (Moshav Elyakhin) and has recently been studied using an archaeometallurgical approach. Based on visual testing and multifocal light microscopy observation, the object was probably produced in a nearby workshop, with the inscription engraved using a sharp tool during the production process. Given the larger assemblage of inscribed copper-alloy artefacts from the site, this item appears not only to have been used as a cultic object, but was also most probably made for the purpose of cultic offerings. The XRF analysis results of the Aramaic-inscribed object after it was sanded revealed the core metal to have been made of relatively pure copper with a tin content of less than 1.0 wt. % Sn. The choice to produce the object using a low-tin copper-alloy indicates that the alloy was chosen based on technological considerations, in order to facilitate plasticity in fashioning th...
Fragments of wall paintings retrieved from Hellenistic Tell Iẓṭabba (Nysa-Scythopolis), an archae... more Fragments of wall paintings retrieved from Hellenistic Tell Iẓṭabba (Nysa-Scythopolis), an archaeological site located in the area of the Beth She'an Valley (Israel), are the subject of this study. This research aims to characterize the plaster and color pigments of wall paintings retrieved from the site in order to gain new information concerning their nature, their origin and the technologies that were used to paint the walls of a Hellenistic settlement in the Near East. For that purpose, visual testing inspection, XRF, SEM-EDS, and XRD analyses were applied combined with archaeological and geographical data. As the site was founded in the<br> 160s BCE and destructed in 108/07 BCE, the material analyzed is not only stratigraphically well-secured but also well-dated to the mid-second century BCE. The walls of the dwellings under discussion were painted by the fresco method and the white-hued plaster was made of calcium carbonate matrix with embedded aggregates. The red an...
A discovery of the use of small metal plates was recently made at the Frankish sites of ‘Atlit, A... more A discovery of the use of small metal plates was recently made at the Frankish sites of ‘Atlit, Arsur and Acre. These plates were used in the masonry, and we suggest for the first time their identification as construction implements that we term “spacers”. At Arsur, due to the homogenous use of relatively small ashlars to maintain level courses of finely built masonry walls, the spacers were found integrated into both interior and exterior walls. These spacers, dated to the second quarter of the thirteenth century, were subjected to metallurgical characterization. Some were made of copper-alloy, probably cast on site and having undergone surface finishing; while the others were corroded ferrous spacers, revealing a heterogeneous microstructure and too were probably produced on site. The present findings contribute to a better understanding of the construction method of stone masonry at Arsur Castle, enabling a deeper insight into a particular building technology.
Fragments of decorated floor tiles were retrieved from the Akko Tower shipwreck, Israel. Most til... more Fragments of decorated floor tiles were retrieved from the Akko Tower shipwreck, Israel. Most tiles were made of bright brown fired clay with a white glaze decorated with colored stenciled motifs (Type A); and others consisted of a red-brown fired clay body, coated with a brown pigment covered with transparent brown glaze (Type B). This study aimed to characterize the two tile types; to reveal information concerning the manufacturing process; and to determine the origin of their raw material. A multidisciplinary approach was used, including light microscopy, SEM-EDS, electron probe microanalysis with wavelength-dispersive X-ray spectroscopy (EPMA-WDS), XRD, Raman spectroscopy, and time-of-flight secondary ion mass spectrometry (TOF-SIMS) analyses. The characterization of both tile types demonstrated the use of different raw materials. The Type A tiles were covered with tin-opacified majolica glaze and colored with various mixtures of pigments. The blue color was due to pigment rich ...
This novel research aims to examine the macro and microstructural bonding region development duri... more This novel research aims to examine the macro and microstructural bonding region development during magnetic pulse welding (MPW) of dissimilar additive manufactured (AM) laser powder-bed fusion (L-PBF) AlSi10Mg rod and AA6060-T6 wrought tube, using both optimal- and high-energy welding conditions. For that purpose, various joint characterisation methods were applied. It is demonstrated that high-quality hermetic welds are achievable with adjusted MPW process parameters. The macroscale analysis has shown that the joint interfaces are deformed to a waveform shape; the interface is starting relatively planar, with waves forming and growing in the welding direction. The observed thickening of the flyer’s wall after welding is the result of its diametral inward deformation, taking place during the process. A slight increase in microhardness was adjacent to the faying interfaces; a higher increase was measured on the AlSi10Mg material side, while a smaller one was observed on the AA6060 s...
Laser powder-bed fusion (LPBF) method is one of the most important additive manufacturing (AM) te... more Laser powder-bed fusion (LPBF) method is one of the most important additive manufacturing (AM) technologies. AM-LPBF parts frequently need post-printing coatings for electrical and thermal conductivity enhancement, or matching decoration considerations. The current study presents a methodology for surface finishing of AM-LPBF AlSi10Mg artifacts coated with electroless gold. For this purpose, gold was deposited on AM-LPBF AlSi10Mg disk-shaped specimens and coins, resulting in an appearance similar to the original objects. The gold coating was characterized as a function of deposition time and gold film thickness. Mass and dimension measurements, optical profilometry, light microscopy observation, XRD analysis and a FIB-SEM technique were applied to characterize the coated samples. The roughness of the plated specimens was slightly reduced as the thickness of the gold film was increased. AM-LPBF AlSi10Mg disk-shaped specimens were coated successfully for the first time by electroless gold plating technique. The developed surface finish technique can be used for various applications, including 3D-printed replicas of ancient prestige artifacts and coins for museum exhibitions.
In the 2016 excavation season of the Akko Tower shipwreck, a ferrous stud-link anchor chain and a... more In the 2016 excavation season of the Akko Tower shipwreck, a ferrous stud-link anchor chain and a rod, both covered with thick encrustation and concretion, were retrieved from the site. The chain links, studs, and rod were analyzed by metallurgical methods, including: radiographic testing, x-ray fluorescence, light microscopy, scanning electron microscopy with energy-dispersive spectroscopy, optical emission spectroscopy, and microhardness measurements, in order to determine their composition and microstructure. The links and the rod were made of wrought iron, while the studs were made of gray cast iron with a significant silicon content of 2 wt.%. The welding zone of the links was identified. The chain was end-welded by forge welding, and the stud was fixed mechanically. The design and manufacturing characteristics of the chain are typical of nineteenth century stud-link anchor chain, which supports the dating of the ship. It is suggested that the chain served the secondary anchor of the ship.
Metals and their alloys were used by ancient civilizations based on their appearance and properti... more Metals and their alloys were used by ancient civilizations based on their appearance and properties. During antiquity, the production process of metal artifacts frequently caused strain hardening, cracking, and loss of strength. In addition, devastating failure has often occurred after long burial periods, resulting from residual stresses and continuous corrosion attack. Therefore, the present study aims to examine how a fracture mechanics approach, integrated with failure analysis tools, may assist archeologists in gaining additional information concerning ancient metal objects. For this purpose, a literature survey of postmortem studies of the RMS Titanic ship's failure is presented, followed by a review of various archeological and historical studies of metal objects and structures made of silver, lead, copper, iron, and their alloys. Lastly, based on the current literature review, a methodology is proposed for analyzing ancient metal artifacts. This approach may assist archeologists in gaining a better understanding of the manufacturing techniques of ancient metal objects, their original shape and dimensions, the cause of failure, and state of preservation and conservation. Moreover, the use of such an approach may be valuable for future conservation and restoration of such archeological metal artifacts.
Annals of Dunarea de Jos University of Galati Fascicle XII Welding Equipment and Technology, 2019
Fused Deposition Modelling (FDM) is one of the most important Additive Manufacturing (AM) technol... more Fused Deposition Modelling (FDM) is one of the most important Additive Manufacturing (AM) technologies. This is a technology suitable for various engineering applications and currently used with many types of thermoplastic materials including Acrylonitrile Butadiene Styrene (ABS). AM-FDM printed ABS possesses an inherent capacity for property modifications as a function of printing parameters. The main goal of the present ongoing research project is to estimate the strength of the AM-FDM printed ABS for varying printing process parameters. In the present study, the mechanical and structural characterizations of AM-FDM ABS were evaluated by light microscopy and mechanical testing. Three-point bend flexural test results revealed the mechanical properties as well as the fracture behaviour according to the dimensions and printing strategies of the build-on specimens. An innovative transmitted-light microscopy experimental method was developed and utilized to investigate the crack propagation behaviour under bending.
The Akko 1 shipwreck is the remains of a 26-metre-long Egyptian armed vessel or auxiliary naval b... more The Akko 1 shipwreck is the remains of a 26-metre-long Egyptian armed vessel or auxiliary naval brig built at the beginning of the 19th century. Remains of six flintlock muskets were retrieved from the shipwreck, and characterised by various metallurgical methods. The research aimed to study the composition and microstructure of the musket fittings and their manufacturing processes, and if possible, to determine the date and origin of the raw materials. The lead isotope analysis of the fittings suggests that their raw material originated in Great Britain. Based on their typology and composition, the fittings were made in Great Britain of brass alloy and manufactured by casting, probably at the same workshop; and the staple was manufactured by casting and drawing. Considering the zinc content, combined with the manufacturing techniques, the fittings were manufactured between the latter part of the 18th and the early 19th centuries, which might indicate that they were purchased in the course of 19th century weapons trade to be used on board the Egyptian ship.
After three excavation seasons the Ma'agan Mikhael B shipwreck has revealed, among other objects,... more After three excavation seasons the Ma'agan Mikhael B shipwreck has revealed, among other objects, seven coins. The coins were found covered with a black concretion layer, which was carefully removed from five of them. Metallurgical methods were used in order to reveal the composition, microstructure, and manufacturing process of the coins and to determine their date and the origin of the raw material. The coins were made of cast copper-lead alloy and were heated before being stamped. Based on the portrait of the House of Constantine I found on coins 120.1 and 120.2, and the figure on coin 120.5, combined with the composition of the coins, they were dated to the fourth century AD, when high concentrations of lead were added to alloys, most probably due to economic constraints. The study of the coins does not identify the ship's origin or her ports-of-call, since coins were essentially mobile.
Seven coins, covered with black concretion coating, found in the Byzantine-period Ma'agan Mikhael... more Seven coins, covered with black concretion coating, found in the Byzantine-period Ma'agan Mikhael B shipwreck, were examined in this study. Metallurgical methods comprising visual testing, XRF, multi-focal light microscopy, SEM-EDS analysis and Raman spectroscopy, were used to determine the corrosion products and microstructure of the coins. The analysis results show that the coins were made of copper-lead alloy with a heterogeneous microstructure of bright and dark metal areas. The external surfaces of the coins were mostly composed of oxides and corrosion product compounds rich in Cu, Pb and Sn, while the external dark concretion coating was rich in Si, S, Ca and C compounds. Gradual variation of the composition and structure of the oxides and concretion coating layers was observed.
A selection of fourth century BCE silver jewelry, which is part of the Samaria and Nablus Hoards,... more A selection of fourth century BCE silver jewelry, which is part of the Samaria and Nablus Hoards, was studied using nondestructive and minimally destructive analyses. A metallurgical methodology was applied and improved, based on the composition of the joints and bulk of the objects. The results indicate that most of the analyzed jewelry is made of silver containing a small percentage of copper, with higher Cu concentrations presented in the brazing and contact melting joints. The manufacturing processes of the jewelry from both hoards involved similar processes, including casting, hammering, bending, cutting, twisting, decorating by plastic deformation, granulating, and three joining methods. These techniques demonstrate that the artifacts were created by trained silversmiths. Our study provides better understanding of the technological skills in the late Persian-period province of Samaria and has implications regarding the production of local silver coins produced in the southern Levant.
Highlights An approach to teaching additive manufacturing (AM) course for engineering students ... more Highlights An approach to teaching additive manufacturing (AM) course for engineering students is suggested. A pedagogical model was developed, based on PDL strategy, for a 14-week AM course. The students designed and 3D printed devices helping people with disabilities. The projects served as useful collaborative learning experiences for AM education. The course demonstrates the potential of AM technologies as innovative environment.
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Papers by Dana Ashkenazi