Environmental Scanning Electron Microscopy Research Articles

Towards the icephobicity evolution of metallic surfaces affected by transitional wettability

In light of the escalating demands for ice protection related applications in diverse fields, including wind energy, power lines and aerospace, there is a notable surge in interest and attention toward the icephobic materials. The increased focus reflects a growing recognition of the crucial role of materials that demonstrate superior resistance to icing phenomenon. However, the intricate correlation between material wettability and icephobicity remains inadequately elucidated. This study aimed to investigate the factors that influence the relationship between icephobicity and different wetting states. The impact of varying surface topographies was examined within the scope of this investigation. A comprehensive analysis was conducted to evaluate the anti-icing and de-icing performances of the surfaces, encompassing anti-frost, ice shear adhesion strength and electro-thermal heating de-icing aspects. Furthermore, the static and dynamic wettability, along with surface free energy measurements, were also performed to enhance the comprehension of icephobicity variation. The detailed water condensation on various surfaces was meticulously observed using environmental scanning electron microscopy (ESEM). The findings elucidated a strong correlation between the icing behaviour and surface topography. It was observed that the surface topography acted as an amplifier, intensifying the deteriorating effect in icephobicity: the formed glaze per unit area exhibited a significant increase with rough asperities; the ice adhesion strength suffered an obvious increase with rough surface and lower hydrophobicity as well as the prolonged ice detachment and overall energy consumption. Therefore, careful consideration should be devoted to the tailoring of surface morphology and wettability when designing and fabricating icephobic surfaces.

Towards dynamic in situ observation of flax fibres under varying water contents through environmental SEM and X-ray tomography

Flax fibre represents one of the most promising natural components for the development of new innovative high-performance biobased composite materials. Their properties are closely related to the lumen, the central cavity of the fibre, which was only studied, to date, under unrealistic environments as in dry conditions. The objective of the current study is to characterise, at a micrometre-scale, the surface and volume modifications induced by exposure of fibres to humid atmospheres. Different dynamic characterization strategies have shown a significant opening of the hydrated lumen "channel". Values of this opening rate are discussed in the light of potential biases linked to the investigation technique (SEM versus X-ray tomography), and to the adopted acquisition approach (in situ versus ex situ). By eSEM, after a 5 min. exposure to the water-saturated environment for instance, the lumen opening value was measured at 36 ± 2% for ex-situ hydration of the bundles with a subsequent delamination of the fibre, while it was only 15 ± 2% when hydration was progressively conducted into the SEM chamber. By microtomography, the lumen swelling for the single fibre was estimated to be within the same order of magnitude, about 7%, after hydration and measurements performed under realistic atmospheric pressure.

Microscopic insights of phase-transition-induced vapor transport enhancement in porous media

Vapor transport in porous media, often associated with liquid-vapor phase change, is an fundamental process in many emerging underground energy storage and extraction processes (i.e., seasonal solar thermal aquifer storage, geothermal extraction, extraterrestrial in-situ water extraction). By jointly using experimental imaging and numerical modeling at the micro-scale, we conduct mechanistic pore scale investigation of capillarity-dominated phase change dynamics and its influence on vapor transport in partially saturated porous rock micromodel. Strongly linked to surface roughness and wettability condition, the capillarity hinders water vaporization from rock surface micro/nano-structures as observed under the environmental scanning electron microscope. By varying the contact angle of 0°, 60°, and 120°, the lattice Boltzmann simulation shows the wettability-dependent vaporization process of capillary-hold water, where pores with hydrophilic surfaces contains significantly more liquid water than that of the hydrophobic ones under the same temperature. When saturated vapor flows through rock porous patterns, capillarity further induces water condensation on the strongly water-wet surfaces. Water condensation, yet forming water bridges/islands and causing the blockage of vapor diffusion, enhances the vapor diffusion ability counterintuitively. The reduction of diffusion path is revealed as the main reason by assessing the local vapor pressure distribution before and after the pore filling by condensate. The findings support the debatable enhancement mechanisms postulated by Philip and de Vries. This work offers the insightful interfacial hydrodynamics of vapor transport in porous media and potentially provides operational guidance for geothermal applications and beyond.

Enhancing microbial-induced carbonate precipitation (MICP) sand consolidation with alkali-treated jute fibers

Recent research has focused on reinforcing sand consolidated through microbial-induced carbonate precipitation (MICP) with alkali-treated fibers to enhance its mechanical properties and mitigate brittleness. This research investigated how modified fiber affected the microstructure and properties of MICP solid sand. The fiber content (0, 0.5, 1, 3, and 5%), pretreatment concentration (0, 1, 5, 10, and 20%), pretreatment time (0, 0.5, 1, 2, and 4 h), and pretreatment temperature (25, 35, 45, and 55 °C) required for the experiment were determined by MICP testing. The interactions between fiber, sand, and calcium carbonate(CaCO3) were analyzed by calcium carbonate content(CaCO3(%)), unconfined compressive strength (UCS), environmental scanning electron microscopy (ESEM), and X-ray diffraction (XRD). The specimen without added fiber had a UCS of 2.13 MPa, the UCS of the added fiber sample was 2.8 MPa, which was 31.46% more than that of the specimen without added fiber, and the UCS of the specimen with added alkali-treated fiber was 3.62 MPa, which was 70% more than that of the specimen without added fiber and 28.57% more than that of the added untreated fiber. The optimum content of jute fibers was 0.5%, and the optimum concentration of alkali treatment of jute fibers was 10% for one hour.

Effect of cementation on the mechanical response of sands using acoustic emission technique

This study investigates the impact of cementation on the mechanical behavior of sands with various cement content (CSR) in drained triaxial compression, employing both Acoustic Emission (AE) and Environmental Scanning Electron Microscopy (ESEM) measurements. The experimental findings, encompassing quantitative statistics of stress-strain relations, microstructure variations, and AE characteristics, demonstrate that: the addition of CSR from 1% to 20% leads to an exponential rise in peak strength and stiffness, marking a transition from ductile to brittle mechanical failure, which is pinpointed between CSR levels of 5% to 10%. AE characteristics unveil an upward-opening parabola of normalized AE hits with CSR, a clear transition zone identification, and three distinct types of AE rate evolutions corresponding to failure patterns of ductile bulging, shear banding, and brittle fracturing, respectively. It suggests an intimate correlation with the intrinsic differences in micro-mechanical behaviors and AE propagation properties of cemented sands with varying CSRs. Notably, the bulging and shear banding processes are divided by AE into three stages, whereas fracturing is characterized into five stages. Two precursory AE anomalies associated with incipient failure and complex failure modes are observed, emphasizing the advantage of using AE to reflect the internal micro-mechanical behavior of cemented sands over conventional stress-strain manifestations.

Effects of removing superficial layer of cartilage on the surface morphology and mechanical behavior of cartilage

Superficial cartilage defect is an important factor that causes osteoarthritis. Therefore, it is very important to investigate the influence of superficial cartilage defects on its surface morphology and mechanical properties. In this study, the knee joint cartilage samples of adult pig were prepared, which were treated by enzymolysis with chymotrypsin and physical removal with electric friction pen, respectively. Normal cartilage and surface treated cartilage were divided into five groups: control group (normal cartilage group), chymotrypsin immersion group, chymotrypsin wiping group, removal 10% group with electric friction pen, and removal 20% group with electric friction pen. The surface morphology and structure of five groups of samples were characterized by laser spectrum confocal microscopy and environmental field scanning electron microscopy, and the mechanical properties of each group of samples were evaluated by tensile tests. The results show that the surface arithmetic mean height and fracture strength of the control group were the smallest, and the fracture strain was the largest. The surface arithmetic mean height and fracture strength of the removal 20% group with electric friction pen were the largest, and the fracture strain was the smallest. The surface arithmetic mean height, fracture strength and fracture strain values of the other three groups were all between the above two groups, but the surface arithmetic mean height and fracture strength of the removal 10% group with electric friction pen, the chymotrypsin wiping group and the chymotrypsin soaking group decreased successively, and the fracture strain increased successively. In addition, we carried out a study on the elastic modulus of different groups, and the results showed that the elastic modulus of the control group was the smallest, and the elastic modulus of the removal 20% group with electric friction pen was the largest. The above study revealed that the defect of the superficial area of cartilage changed its surface morphology and structure, and reduced its mechanical properties. The research results are of great significance for the prevention and repair of cartilage injury.

Study on modified graphene oxide-based emulsion cleaner for oily sludge

Abstract Oily sludge is a complex system that is inevitably generated during the process of oil extracting and processing. It will cause serious environmental pollution and waste of resources if untreated sludge is discharged. In this paper, a composite emulsion cleaner based on modified graphite oxide and surfactants was developed for cleaning oily sludge. First, graphite oxide (GO) was functionally modified with butylamine, and its structures were verified by Fourier transform infrared spectroscopy (FTIR), X-ray electron spectroscopy (XPS), thermogravimetric analysis (TGA), and environmental scanning electron microscopy (SEM). Then, the oil-in-water composite emulsion cleaner was prepared by using butylamine modified graphite oxide and surfactants. The conditions for emulsion preparation and oil sludge cleaning were modelled and optimized by the response surface methodology. The obtained optimal formulations were: surfactant content was 2.17 ‰ with SDS/AEO-3 ratio of 9:1, GO-A4 content was 0.96 ‰, water-oil ratio was 5:5, and the oil removal rate was 97.45 %. The optimal cleaning conditions were: liquid-solid ratio of 3.2:1, cleaning time of 32 min, cleaning temperature of 28.7 °C, and oil removal rate of 99.02 %. The solid sediments were characterized by FTIR and SEM, which proved the feasibility of cleaning oily sludge with the emulsion.

Crystallographic faceting of bulk tungsten surfaces observed during in situ heating in an environmental scanning electron microscope

The surface faceting of metals has been studied for several decades, typically using experimental methods such as low-energy electron diffraction. In the current paper, surface faceting of tungsten pellets was studied during in situ heating inside an environmental scanning electron microscope (ESEM), which allowed for direct, high-fidelity observation of morphological changes in response to high-temperature annealing under a moderate vacuum (0.8 Torr). Additionally, a second set of tungsten samples was annealed in an ultrahigh vacuum chamber (10−8 Torr), albeit without direct observation via ESEM. This study revealed that oxygen plays a crucial role in tungsten surface faceting and in a morphological transition to vertex rounding. Furthermore, this paper discusses relevant techniques for identifying the crystallographic indices of surface facets. It is demonstrated that a combination of electron backscatter diffraction, tilted-sample imaging from multiple angles, and serial sectioning in a focused ion beam system can be effectively deployed to determine the geometry of faceting, which in turn can be verified with the aid of software for generating Wulff shapes. The influence of processing environment on tungsten surface faceting enables the possibility of designing and controlling the morphology and crystallographic facets of tungsten surfaces.

Effect of different surface roughening treatment on polyether ether ketone and acrylic resin bonding: A pilot study.

As polyether ether ketone (PEEK) is a relatively new material in dentistry, its bonding properties with regard to dental acrylic base materials are not fully known. To ensure the long-term success of removable dentures with a PEEK framework, the base materials must be well bonded to each other. The study aimed to investigate the effects of different kinds of surface roughening treatment on PEEK and acrylic resin bonding. Eighty PEEK specimens (N = 80) were randomly divided into 5 groups (n = 16 per group) and subjected to various surface roughening treatment (control, grinding, sandblasting, tribochemical silica coating (CoJet), and sulfuric acid etching). Heat-polymerized acrylic resin was applied to the treated surfaces of the PEEK specimens. The shear bond strength (SBS) test, environmental scanning electron microscopy (ESEM) analysis and three-dimensional (3D) surface topography analysis were performed. The statistical analysis of the data was conducted using the analysis of variance (ANOVA) and Tukey's multiple comparison test. The one-way ANOVA showed significant differences in the SBS values between the groups (p = 0.001). Sandblasting, tribochemical silica coating and sulfuric acid etching resulted in high SBS values (p = 0.001). The highest SBS values were observed in the sulfuric acid etching group (8.83 ±3.63 MPa), while the lowest SBS values were observed in the control group (3.33 ±2.50 MPa). The additional roughening treatment applied to the PEEK surface increases the bond strength with heat-polymerized acrylic resin.

Computational and experimental microfluidics: Total analysis system for mixing, sorting, and concentrating particles and cells.

Body fluids can potentially indicate the presence of non-small cancer cells. Studying these fluids is an emerging field that could be crucial for cancer detection and monitoring treatment effectiveness. Meanwhile, the examination of fluids on a microscopic level is part of the field of microfluidics. This study focuses on the development of a total analysis system that consists of various interconnected structures that are designed to mix, classify, concentrate, and isolate particles in fluids that mimic the behavior of cancer and normal cells. Using the COMSOL Multiphysics software, the device's performance was optimized to use a pressure input of 35 kPa for water or serum and 29.4 kPa for a mixture of liquid and serum samples, which are the optimal pressure inputs. The numerical models were validated by experiments using two types of polystyrene particles, with diameters of 5 and 20 μm. Moreover, the developed system was applied to monitor the behavior of red blood cells. The microfluidic chip is capable of addressing several challenges through visual detections, including mixing tests of two fluids with similar densities, proper particle size classification using Dean flow fractionation, and single-step recovery of large, labeled particles. Finally, the collected particles were examined using an environmental scanning electron microscope to determine their size, and the results demonstrated that successful size separation was achieved, with particles around 20 μm completely separated from the smaller ones.

Experimental study on durability of steel-basalt fiber reinforced concrete under multiple factors coupling

A series of durability tests were conducted using varying composite salt solutions (5% Na2SO4 + 3.5% NaCl, 10% Na2SO4 + 3.5% NaCl, and 3.5% NaCl) and stress levels (F-0.3, F-0.6) to investigate the durability of concrete reinforced with steel and basalt fibers. Specimens were extracted after 0, 25, 50, 75, 100, 125, and 150 wet-dry cycles to explore the changes in the appearance, mass loss, relative dynamic modulus of elasticity, and compressive strength with the number of wet-dry cycles and different coupling effects. Mathematical models correlating mass and compressive strength with wet-dry cycles and stress levels were separately established. The concrete microstructure under coupling effects was observed using Environmental Scanning Electron Microscopy (ESEM). The results indicated that the inhibitory effect on the increase in concrete mass was higher in the F-0.6 group than in the F-0.3 group, showing that concrete under F-0.3 exhibited faster mass growth. As the axial compressive stress ratio increased, steel-basalt fiber reinforced concrete's relative dynamic modulus of elasticity changed less. Concrete degradation was more pronounced in the 10% Na2SO4 + 3.5% NaCl solution and F-0.6 loading environment. The calculated results from the established models agreed with the experimental results, demonstrating a certain degree of feasibility.

Microscopic enrichment and porosity-permeability reduction mechanism of residual oil in tight sandstone reservoirs: an insight from Chang 8 Member, Yanchang Formation, Ordos Basin, China

AbstractThis study delves into the micro-occurrence states and enrichment mechanisms of residual oil, pivotal for advancing the production from tight sandstone reservoirs, particularly from the Chang 8 Member of the Upper Triassic Yanchang Formation, Ordos Basin. Through an analysis of 23 core samples, employing high-pressure mercury injection, field emission scanning electron microscopy, thin section, and X-ray diffraction techniques, distinct reservoir types were categorized. The utilization of environmental scanning electron microscope, multi-solvent continuous extraction, and an oil components separation system facilitated an intricate analysis of residual oil micro-occurrence states and their subsequent effects on porosity and permeability reduction across varying reservoir types. The findings accentuate the integral role of reservoir type in determining residual oil distribution within tight sandstone reservoirs. Favorable pore throat sorting and connectivity in specified reservoir types are identified as conducive to residual oil enrichment with a higher concentration of light components. In contrast, elevated carbonatite and clay content in other reservoir types leads to adsorption of heavy components, disrupting pore throat connectivity, and impeding crude oil filling. The varied interactions between oil and rock, oil–oil, and pore throat sealing significantly impact the distribution of oil components of residual oil, culminating in a notable reduction of porosity and permeability by 2.63% and 0.197 mD, with corresponding reduction rates of 27.19% and 46.69%, respectively. The insights derived from this study furnish a theoretical foundation for augmenting tight oil recovery and comprehending the enrichment mechanism of residual oil driven by the heterogeneity of tight sandstone reservoirs.

The Impact of Nozzle Opening Thickness on Flow Characteristics and Primary Electron Beam Scattering in an Environmental Scanning Electron Microscope.

This paper describes the methodology of combining experimental measurements with mathematical-physics analyses in the investigation of flow in the aperture and nozzle. The aperture and nozzle separate the differentially pumped chamber from the specimen chamber in an environmental scanning electron microscope (ESEM). Experimental measurements are provided by temperature and pressure sensors that meet the demanding conditions of cryogenic temperature zones and low pressures. This aperture maintains the required pressure difference between the chambers. Since it separates the large pressure gradient, critical flow occurs on it and supersonic gas flow with the characteristic properties of critical flow in the state variables occurs behind it. As a primary electron beam passes through the differential pumped chamber and the given aperture, the aperture is equipped with a nozzle. The shape of the nozzle strongly influences the character of the supersonic flow. The course of state variables is also strongly influenced by this shape; thus, it affects the number of collisions the primary beam's electrons have with gas molecules, and so the resulting image. This paper describes experimental measurements made using sensors under laboratory conditions in a specially created experimental chamber. Then, validation using mathematical-physical analysis in the Ansys Fluent system is described.

Modeled versus Experimental Salt Mixture Behavior under Variable Humidity.

This study investigates the kinetics of salt mixture crystallization under relative humidity (RH) conditions, varying between 15 and 95% (at 20 °C), to inform applications in built heritage preservation, geology, and environmental sciences. We focused on commonly found, sulfate-rich and calcium-rich salt mixtures containing five to six ions, Cl-, NO3-, Na+, and K+, including or excluding less common Mg2+, and including either an excess of SO42- or Ca2+, with respect to gypsum. Using time-lapse micrographs and dynamic vapor sorption, we explore how crystallization and dissolution behavior depend on RH and mixture composition under constant temperature. A range of RH change rates were studied to simulate realistic weather events. Microstructural analyses through environmental scanning electron microscopy (ESEM) confirmed the crystal habit corresponding with RH transitions. Phases predicted from thermodynamic modeling (ECOS/RUNSALT) were confirmed using micro-Raman spectroscopy, X-ray diffraction (XRD), and elemental mapping via energy-dispersive X-ray spectroscopy (EDX). We identify a strong correlation between phase transition kinetics and RH change rates, with crystallization deviating by -15% and dissolution by +7% from modeled values under rapid (several seconds) and slow (several days) RH changes. These insights are important for preservation strategies in built heritage, salt deposition, and dissolution mechanisms in diverse geological and realistic environmental contexts, laboratory experiments, future modeling efforts, and the understanding of stone decay in general.

Real-time imaging of oil shale pyrolysis dynamics at nanoscale via environmental scanning electron microscopy

Pyrolysis is a promising technology to increase pore and fracture connectivity in oil shale and thereby accomplish commercial recovery of unconventional hydrocarbons. Herein, real-time oil shale pyrolysis dynamics are imaged at nanoscale via environmental scanning electron microscopy (imaging resolution of 58 nm/pixel, imaging speed of 1 frame per second, and heating temperature up to 750 °C). It is counterintuitively observed that 1) inorganic nano-fractures started to appear below 100 °C; 2) inorganic nano-fracture width had a non-monotonous relationship with temperature; and 3) organic kerogen areas decreased monotonously with increasing temperature. These findings will establish a standard benchmark for unconventional resource recovery, promote fundamental understanding of oil shale pyrolysis dynamics at nanoscale and provide key guidance on oil shale extraction at reservoir scale.

Engineering Biodegradable Sodium Alginate Films with Dragon Fruit Peel Powder and MgO Nanoparticles

This study investigated the effect of the addition of dragon fruit peel powder (DFP) and MgO nanoparticles on sodium alginate (SA) films. The control film (S1 film), DFP-enriched (S2 film), MgO nanoparticles-enhanced (S3 film), and a film combining both MgO nanoparticles and DFP (S4 film) were evaluated. The tensile strength increased by 252.43, 290.27, and 645.13% for the S2, S3 and S4 films, respectively. These enhancements were accompanied by a marked improvement in the UV-blocking property, thermal stability, antioxidant activity,2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activity, opacity and thickness. The water vapor permeability and transparency were decreased to 3.45 × 10−10 g−1 Pa−1 S−1 and 1.82% for the S4 film. An environmental scanning electron microscope (ESEM) study revealed a notable increase in surface roughness with the incorporation of DFP. X-ray diffraction (XRD) analysis indicated that the MgO nanoparticles possessed a crystallographic structure that was compatible with the SA film matrix, with the S4 films exhibiting the highest crystallinity index (28.92%). The overall migration study showed that all SA films complied with the overall migration limit of 60 mg/kg of simulant for fatty food simulants. The biodegradability test revealed complete degradation of the S1, S3, and S4 films before 20 days while the S2 film exhibited a substantial mass loss of 84.99% within the same 20-day timeframe.

Influence of curing temperature and pressure on the mechanical and microstructural development of metakaolin-based geopolymers

This research investigates the mechanical and microstructural evolution of a metakaolin-based geopolymer (GP) subjected to combined temperature and pressure curing conditions. The study's methodology encompassed measuring compressive strengths through both ultrasonic cement analysis (UCA) and destructive uniaxial testing. To evaluate thermal stability, pore size distribution, and morphology, the study employed thermogravimetric analysis (TGA), mercury intrusion porosimetry (MIP), and environmental scanning electron microscopy (ESEM), respectively. The findings indicate that a curing temperature of 90 °C encourages the development of regular nanoporosity, while higher temperatures contribute to increased porosity. Conversely, curing pressure was found to either promote or inhibit the material's reorganization, with pressures of 20 MPa facilitating and those above 40 MPa preventing this process. An enhancement in the refinement of macropores to micropores was observed across all pressure levels. The optimal curing conditions, in terms of both mechanical and morphological characteristics, were identified as 50 °C and 20 MPa for a minimum duration of one day, which yielded a 177 % improvement in compressive strength compared to curing at 21°C under atmospheric pressure. This study significantly advances the understanding of pressurized thermal curing processes for the rapid setting of geopolymers, presenting new avenues for diverse applications.

Synthesis of phosphate hydrogels with excellent swelling behavior prepared by ascorbic acid -mediated ARGET ATRP

This manuscript explores the synthesis of hydrogels through reversible deactivation radical polymerization (RDRP) methods, specifically, activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) and Cu0-mediated ATRP. These techniques are known to offer improved control over polymer network structures due to their slow polymerization kinetics. However, these methods have historically been challenging to apply to stimuli-responsive polymers, such as those with acidic or basic moieties. In this study, the direct synthesis of poly(2-(methacryloyloxy) ethyl phosphate) (PMOEP), a phosphate-pendant hydrogel, was investigated in aqueous media by both ascorbic acid (AsA)-mediated ARGET ATRP and Cu0-mediated ATRP. 2-(methacryloyloxy) ethyl phosphate (MOEP) was utilized as the active monomer with tris(2-pyridylmethyl) amine (TPMA) as the ligand. A unique feature of this work is that the diene moiety inherently present in the commercial monomer, bis[2-(methacryloyloxy) ethyl] phosphate (BMOEP), served as the crosslinking agent to obtain the novel PMOEP hydrogel. Formulations were tuned to optimize the swelling characteristics of the hydrogels, with the restriction that the hydrogels should swell homogeneously without fracture. Importantly, using AsA as the reducing agent in the ARGET ATRP reaction resulted in improved homogeneity and enhanced swelling properties of the hydrogel. Furthermore, tuning the target degree of polymerization (Dp) ([monomer]:[initiator]) had a significant impact on swelling characteristics. Specifically, PMOEP hydrogels synthesized via ARGET ATRP with a target Dp of 300 and 1 mM CuII catalyst demonstrated outstanding water absorption capacity of more than 2500% (relative to the dry mass) in phosphate buffer solution (PBS) at pH 7.4 and over 6000% in pure water. The morphology of these hydrogels was imaged using field emission environmental scanning electron microscopy (FE-ESEM) and the chemical composition was examined using Fourier transform infrared (FTIR) spectroscopy. Furthermore, nuclear magnetic resonance (NMR) analysis was performed to investigate the conversion rate of monomer during Cu0-mediated ATRP. To the authors’ knowledge, the synthesis of a 100% phosphate-pendant hydrogel using AsA-mediated ARGET ATRP and an internal phosphodiester crosslinking moiety without dilution or comonomer, has not been reported previously. This facile method for synthesizing and controlling phosphate-based hydrogel properties also provides an opportunity to include additional functional groups and holds significant promise for applications in biomedical engineering, agriculture, and membrane separations.

Characterization of Tableware from Fábrica de Loiça de Sacavém—Linking Analytical and Documental Research

Fábrica de Loiça de Sacavém (ca. 1858–1994) was among the first to produce white earthenware in Portugal, becoming one of the country’s leading ceramic manufacturers during the late 19th to early 20th centuries. Research on white earthenware has accompanied the growing interest in post-industrial archaeology but is still poorly explored compared to more ancient ceramic productions. This study focused on the ceramic body, glazes, and colourants of tableware produced by Fábrica de Loiça de Sacavém during the first 50 years of its activity (1859–1910). A multi-analytical approach was selected to investigate the chemical and mineralogical composition of the ceramic body, glaze, and pigments using optical microscopy, variable-pressure scanning electron microscope energy-dispersive X-ray spectroscopy (VP-SEM-EDS), μ-Raman spectroscopy, μ-X-ray Diffraction (μ-XRD), and reflectance spectroscopy (hyperspectral image analysis). The studied tableware was produced with a Ca-poor siliceous–aluminous white earthenware ceramic body covered with transparent alkali lead or lead borosilicate glaze, and most colourants were complex Cr-based pigments. These results are in agreement with the little documental evidence from this period found in the manufacturer’s archives.

Frequency-based electric fingerprint and thermal properties of the NWA 869 chondrite

The NWA 869 chondrite is among many common stony regolith breccia meteorites that have been collected from northwest Africa (NWA). It is composed of Fe sulphide and Fe-Ni metallic phase inclusions embedded in a silicate stony matrix (primarily pyroxene). Although the physical properties of meteorites are the implementation of their mineral and chemical compositions, their electric and dielectric properties (electric conductivity σ, dielectric constant ε′, and dielectric loss ε") are rarely studied, while no literature has been published on their thermal properties (thermal conductivity K, thermal diffusivity α, specific heat capacitance Cp, and thermal effusivity e). Consequently, the present study deals with studying the electric and dielectric properties of the NWA 869 chondrite at a frequency range (4.0 Hz-8.0 MHz), and their behavior against the applied frequency (fingerprint) was matched. Also, the thermal properties were measured at the ambient conditions. The porosity and density of the chondrite were also measured using helium injection technique. To explain the electric and thermal properties of the meteorite sample, its internal structure as well as its mineral and chemical compositions were revealed using the environmental Scanning electron microscopy (ESEM) supported by the EDAX technique. It is indicated that the chondrite is composed of iron sulphide and Fe-Ni inclusions scattered in a stony silicate matrix; it is characterized by moderate density (3.5069 g/cc) with a considerable porosity value (2.12 %). It is also characterized by moderate electric conductivity (σ), dielectric constant (ε′), and dielectric loss (ε") values (0.50 < σ < 2037.3 ohmm, 67.0 < ε' < 1713.7, and 0.22 < ε" < 12,432 at frequency range 4 Hz-8MHz, respectively). Also, it is characterized by thermal conductivity (K), thermal diffusivity (α), thermal capacitance (Cp), and thermal effusivity (e) values of average 1.5185 W/(K.m), 1.5425 mm2/s, 286 J/(K.kg), and 2628 W(s)0.5/m2K, respectively.