Microstructural characterization of chitosan and alginate films by microscopy techniques and texture image analysis

2012 ◽  
Vol 87 (1) ◽  
pp. 289-299 ◽  
Author(s):  
Israel Arzate-Vázquez ◽  
José Jorge Chanona-Pérez ◽  
Georgina Calderón-Domínguez ◽  
Eduardo Terres-Rojas ◽  
Vicente Garibay-Febles ◽  
...  
Keyword(s):  
Image Analysis ◽  
Microstructural Characterization ◽  
Texture Image ◽  
Microscopy Techniques

scholarly journals Microstructural characterization of snow, firn and ice

2019 ◽  
Vol 377 (2146) ◽  
pp. 20180162 ◽  
Author(s):  
Ian Baker
Keyword(s):  
Optical Microscopy ◽  
Microstructural Characterization ◽  
Theme Issue ◽  
Thin Sections ◽  
X Ray ◽  
The Future ◽  
Microscopy Techniques

This paper provides an overview of techniques used to characterize the microstructure of snow, firn and ice. These range from traditional optical microscopy techniques such as examining thin sections between crossed polarizers to various electron-optical and X-ray techniques. Techniques that could have an impact on microstructural characterization of snow, firn and ice in the future are briefly outlined. This article is part of the theme issue ‘The physics and chemistry of ice: scaffolding across scales, from the viability of life to the formation of planets’.

scholarly journals Microscopy characterization of metallurgical production evidences from Vila Nova de São Pedro (Azambuja, Portugal)

2013 ◽  
Vol 19 (S4) ◽  
pp. 149-150
Author(s):  
F. Pereira ◽  
R.J. Silva ◽  
A.M. Monge Soares ◽  
M.F. Araújo
Keyword(s):  
Elemental Composition ◽  
Chemical Elements ◽  
Research Work ◽  
Analytical Techniques ◽  
Microstructural Characterization ◽  
Chemical Homogeneity ◽  
Metallurgical Production ◽  
Microscopy Techniques ◽  
Arsenical Copper

The Castro de Vila Nova de São Pedro (VNSP) is an emblematic settlement located at Azambuja (Portugal), occupied predominantly during the Chalcolithic period. A large and diversified metallurgical collection was recovered from this settlement which includes artefacts, crucibles and other metallurgical production remains, like slags and droplets. The chemical and microstructural characterization of this metallic collection aims to contribute to a better comprehension of the early copper-based metallurgy on the Portuguese Estremadura, the degree of knowledge of the ancient metallurgists and the role of the metallurgical activities in Chalcolithic societies.A group of 53 selected copper-based fragments of artefacts plus metallurgical production remains (12 crucibles and 20 slags and droplets), all belonging to VNSP, were characterized by using different analytical techniques: EDXRF and micro-EDXRF spectrometry, optical microscopy (OM) and SEM-EDS. The EDXRF and micro-EDXRF spectrometry gives the elemental composition of the artefacts and metallic nodules. The microscopy techniques play a fundamental role in the chemical and microstructural characterization of artefacts and metallurgical remains. The OM allows the identification of different phases, inclusions and thermomechanical processes applied during the shaping of the artefacts. The SEM-EDS plays an important role in the determination of main chemical phases present in the metal alloy and slags, and also in the distribution of chemical elements and minerals in the inclusions. The combination of these two microscopy techniques gives indication of the processes used in the reduction of minerals in order to obtain the metal and also allows the characterization of the operation chain, regarding the production of artefacts.The research that has been carried out by us offer indications concerning the provenance of the arsenic, the technological choices involved in the production of an arsenical copper alloy and how it was recognized by ancient metallurgists. Results obtained on the elemental composition of the metallurgical production remains are consistent with copper and arsenical copper (As > 2 %) artefact production. Crucibles and slags analysed indicate melting and smelting operations (of copper ores or copper/arsenic ores). A statistically significant association was found between copper alloyed with arsenic and artefacts classified as tools/weapons (arrowheads, daggers and knives). In several cases, the presence of arsenic rich phases in the microstructure, resulting from an inverse segregation phenomenon, shows no evidence of chemical homogeneity control during the artefact manufacture. Microstructural analyses also show that the majority of the artefactual group was shaped with forging plus annealing operation cycles and 23 % of the artefacts received a final forging treatment. This final treatment was associated to artefacts presenting higher arsenic contents.This research work has been financed by the Portuguese Science Foundation (FCT-MCTES) through the EarlyMetal project (PTDC/HIS-ARQ/110442/2008) and the PhD Grant SFRH/BD/78107/2011 (FP). The financial support of CENIMAT/I3N through the Strategic Project-LA25-2011-2012 (PEst-C/CTM/LA0025/2011) is also acknowledged.

scholarly journals Microstructural Characterization of Alloy 617 Crept Into the Tertiary Regime

2015 ◽  
Author(s):  
Thomas M. Lillo ◽  
Richard N. Wright
Keyword(s):  
Image Analysis ◽  
Creep Strain ◽  
Void Formation ◽  
Microstructural Characterization ◽  
Low Energy ◽  
Creep Tests ◽  
Alloy 617 ◽  
Creep Stress ◽  
Creep Strains

The dislocation structure and area fraction of creep voids in Alloy 617 were characterized following creep tests interrupted at total creep strains ranging from 2–20%. A range of creep temperatures (750–1000°C) and initial creep stresses (10–145 MPa) produced creep test durations ranging from 1 to 5800 hours. Image analysis of optical photomicrographs on longitudinal sections of the gage length was used to document the fraction of creep porosity as a function of creep parameters. In interrupted creep tests performed at 750°C, minimal levels of creep porosity were found even in samples crept to ∼20% total creep strain. At 1000°C, creep porosity was negligible below total creep strains of 10% and increased thereafter with increasing total creep strain. Also, creep porosity increased with decreasing creep stress for a given total creep strain. TEM performed on the gage sections did not reveal significant creep void formation on grain boundaries or in the grains at the sub-micron level. However, dislocation boundaries exhibited extensive dislocation rearrangement and dislocation-dislocation reactions. It was concluded that the onset of tertiary creep did not result from creep void formation and more likely arose due to the formation of low energy dislocation substructures.

Thermal Analysis of Aluminum Alloys

2019 ◽  
Author(s):  
Consuelo García-Cordovilla ◽  
Enrique Louis
Keyword(s):  
Thermal Analysis ◽  
Aluminum Alloys ◽  
Physical Properties ◽  
Reaction Kinetics ◽  
Microstructural Characterization ◽  
Basic Principles ◽  
General Rules ◽  
Microscopy Techniques

Microstructural characterization of aluminum alloys is typically performed by combining microscopy techniques with measurement of physical properties such as conductivity and hardness. Relatively recently calorimetric techniques have been used to complement the more traditional methodologies. This article will discuss: basic principles, instrumentation and experimental procedures, reaction kinetics, and general rules for interpreting DTA and DSC data. Heat treatable, non-heat treatable alloy and aluminum-based composite characterization are discussed.

Effect of Parawood Ash on Drying Shrinkage, Compressive Strength and Microstructural Characterization of Metakaolin-Based Geopolymer Mortar

2013 ◽  
Vol 594-595 ◽  
pp. 411-415 ◽  
Author(s):  
Danupon Tonnayopas ◽  
Abideng Hawa ◽  
Woraphot Prachasaree ◽  
Pichai Taneerananon
Keyword(s):  
Compressive Strength ◽  
Microstructural Analysis ◽  
Drying Shrinkage ◽  
Microstructural Characterization ◽  
Partial Replacement ◽  
X Ray Diffraction ◽  
Microscopy Techniques ◽  
Metakaolin Geopolymer ◽  
Test Result

Drying shrinkage, compressive strength and microstructural analysis of metakaolin based geopolymers partial replacement with Parawood ash was investigated. It was involved different SiO2/Al2O3 and CaO/SiO2 ratios. Characterization of geopolymer mortar was determined on drying shrinkage, compressive strength, mineral phases and microstructure was analysed by X-ray diffraction and scanning electron microscopy techniques. Test result of highest compressive strength was about 71 MPa at 6-h (4-h in oven at 80oC and 2-h ambient temperature). Voids-cement ratio is the most effect on the unconfined compressive strength of this metakaolin geopolymer mortar.

Investigating the effects of traveling speeds and post-weld heat treatment on mechanical properties of nano-Al2O3-fortified AA6061-T6 friction stir welds

2016 ◽  
Vol 232 (10) ◽  
pp. 816-828 ◽  
Author(s):  
H Yousefpour Naghibi ◽  
H Omidvar ◽  
M Farahmand Nikoo
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Solution Heat Treatment ◽  
Microstructural Characterization ◽  
Post Weld Heat Treatment ◽  
Nano Particles ◽  
Friction Stir ◽  
Microscopy Techniques ◽  
Weld Heat

In this study, 6 mm thick AA6061-T6 plates were friction stir welded (FSWed) at different traveling speeds while Al2O3 nano-particles were incorporated between adjoining plates. The solution heat treatment was applied on samples for one hour at 540 ℃ and subsequently aged for 18 h at 180 ℃ to investigate the effect of post-weld heat treatment on mechanical properties of specimens. All joints were investigated macro- and micro-structurally. The microstructural characterization of the FSWed samples was carried out using scanning electron microscopy (SEM) and light microscopy techniques. Distribution of Al2O3 nano-particles in the stir zone was studied by SEM. The specimen FSWed at 40 mm/min exhibited the most homogeneous particles distribution. Tensile properties including ultimate tensile strength, elongation, and fracture surfaces were studied. Microhardness of specimens was also investigated. Surprisingly, all specimens exhibited inferior hardness compared to the as-received AA6061-T6 alloy. This phenomenon was attributed to the dissolution of precipitates during FSW process.

scholarly journals A microstructural characterization of some Late Bronze Age metals from Fraga dos Corvos site: fibula, pendants, riveted sheet and droplet

2013 ◽  
Vol 19 (S4) ◽  
pp. 141-142
Author(s):  
F. Lopes ◽  
R.J. Silva ◽  
E. Figueiredo ◽  
M.F. Araújo ◽  
J. Reprezas ◽  
...  
Keyword(s):  
Bronze Age ◽  
Financial Support ◽  
Cast Alloy ◽  
Dendritic Structure ◽  
Microstructural Characterization ◽  
Metal Artefacts ◽  
Slip Bands ◽  
Thermomechanical Processes ◽  
Microscopy Techniques

The knowledge of our pre-history and ancient metal artefacts production methods can only be deeply investigated through the multidisciplinary approaches involving different analytical techniques including microscopy techniques. The present study concerns the elemental and microstructural characterization of pre-historic bronze artefacts from the Northwestern Iberia Peninsula. During Bronze Age an increment of metal artefacts production and its typological diversification is observed related to the development of metallurgical technology. Several artefacts have been found during recent excavations at the Bronze Age settlement of Fraga dos Corvos (Macedo de Cavaleiros, Portugal). The analysis of metallurgical remains points out to the existence of local metallurgical activities. Five bronze artefacts previously analysed by micro-EDXRF, an Acebuchal fibula fragment, two pendants and a riveted sheet (probably a fragment of a vessel or cauldron) with average concentration values of 10±1.1% Sn and ~2±0.5% Pb and a droplet (?) with ~5% Sn and ~4% Pb, were selected for optical microscopy (OM) and SEM-EDS analysis.Microscopy observations showed to be very important for the comprehension of pre-historic bronze metallurgy, allowing the identification of different phases, inclusions and thermomechanical processes applied during artefacts production. The fibula and the pendants show an equiaxed and twinned microstructure with slip bands (Figure 1 (a) and (c)). The characteristics observed are related to recrystallized and plastically deformed α-Cu structures. These features indicate that the artefacts were hammered and annealed (thermomechanical cycling), ending with a hammering operation. The pendants only exhibit slip bands near the surface, probably resulting from a finishing operation. Lead and Cu-S inclusions are frequently observed. The riveted sheet has an annealed microstructure with large α-Cu grains, undissolved (α+δ) eutectoid and few annealing twins. Elongated Cu-S inclusions, lead globules and pores were identified by SEM-EDS (Figure 1 (a)). Its microstructure indicates that shaping was obtained by just one or few thermomechanical cycles. The droplet presents a coarse and cored dendritic structure (Figure 1 (b)). Rounded Cu-S inclusions, lead globules and pores were also observed. Those are characteristics of a slow cooled as-cast alloy. Due to its low Sn content the (α+δ) eutectoid is absent. As a final note, microscopy techniques allowed establishing the manufacture processes involved in bronze metallurgy and to conclude that different thermomechanical processes were applied according to the typology of the artefact.Financial support received from the Portuguese Science and Technology foundation under the EarlyMetal project PTDC/HIS-ARQ/110442/2008 and the grants SFRH/BPD/73245/2010 (EF) and SFRH/BD/72369/2010 (EL). Financial support of CENIMAT/I3N through the Strategic Project LA25/2011-2012 (PEst-C/CTM/LA0025/2011) is gratefully acknowledged.

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