Prior Thermal Treatment Research Articles

Influence of aging temperature on the microstructure and mechanical properties of a Cu-2Be alloy

As a contribution to existing knowledge, this work studied the evolution of the hardness, elastic modulus and microstructure of an age-hardenable Cu-2Be alloy when subjected to aging treatments at different times, in order to obtain the hardness curves at all stages, and for different aging temperatures in the range of 320–400 °C. In addition, the effect of performing a prior heat treatment consisting of 2 h at 225 °C on the mechanical behavior of the material was analyzed. The elastic modulus and hardness were measured using IET technique and Vickers hardness, respectively. The best mechanical properties (higher hardness values and high elastic modulus) were obtained for treatments at aging temperatures of 320 and 350 °C, with aging times of 40 and 5 h, respectively. The maximum hardness decreases with temperature and increases by about 25 HV by performing a prior thermal treatment at 225 °C. At the maximum hardness peaks, the elastic modulus exhibits similar values, while the asymptotic value increases slightly with temperature. SAXS measurements were used to study the size and shape of the nanoprecipitates formed after aging treatments at different temperatures and times. At the hardness peaks, precipitates have ellipsoid shapes and their size increases with the temperature from 18 to 30 nm. After the hardness peak at 400 °C, the hardness and modulus decrease slightly, while the precipitate size increases to 58 nm.

Characterisation, activation, and reactivity of heterogenous natural clays

Although thermal and mechanochemical activations of natural clays are well-documented, there exists a dual research gap. Firstly, a thorough investigation into the interrelationship between these activation methods and the governing parameters of reactivity for various clays has been notably lacking. Secondly, there is a distinct scarcity of studies specifically focusing on heterogeneous clays compared to the extensive research dedicated to single-layer clays specially kaolinitic clays. This study investigates the correlation of activation methods, and changes in the clay mineralogy, particle size distributions, morphology, specific surface area, and the reactivity of heterogeneous clays. Traditional thermal and mechanochemical activation methods often fall short in achieving complete dehydroxylation of heterogeneous clay minerals and improving their reactivity beyond predefined low thresholds. The results in this paper emphasize that, despite these limitations, combining these activation methods brings about significant modifications in crucial parameters. Notably, integrating 20 min of mechanochemical activation at 500 rpm with prior thermal treatment leads to 158% increase in specific surface area compared to mechanochemical activation conducted on un-calcined clays. Simultaneously, these combined activations result in up to 127% improvement in reactivity levels of heterogenous clays compared to standalone mechanochemical activation. The results underscore that, even with the advancements brought about by combined activations, the presence of impurities like iron oxides and calcite remains a noteworthy factor influencing the reactivity of kaolinitic natural clays. The study concludes by highlighting the potential of combined treatments to enhance the pozzolanicity of low-reactive heterogeneous clays, unlocking avenues for future clinker supplementation with this abundant resource.

Tensile properties of thermoset composites based on yarn structures from recycled carbon fibre and low melting temperature Co-polyamide fibre

The tensile properties of thermoplastic composites based on hybrid yarn structures consisting of recycled carbon fibre (rCF) and thermoplastic fibres (rCF content of the hybrid yarn approx. 50–60% by weight) have been reported previously. To date, no report has been found on the tensile properties of thermoset composites based on yarns with high rCF content (>90% by weight). The reasons for this are the complex mechanisms involved in processing pure rCF due to the low shear strength, smooth fibre surface, small fibre diameter and high brittleness of rCF. Yarns made of rCF (≥90% weight) for thermoset composites have been developed in a fundamental research project at the ITM. This paper reports on the tensile properties of unidirectional composites based on yarns composed of staple rCF (>90%) and low melting co-polyamide fibres produced by varying spinning parameters. Furthermore, in order to increase the infiltration of the epoxy matrix during the composite manufacturing process, the yarns are thermally treated at 180°C prior to infiltration and its effect on the tensile properties of the composites is analysed. The results show that the thermal treatment of the yarn prior to infiltration with the matrix, compared to the yarn without prior thermal treatment, helps to achieve better impregnation and therefore better tensile strength of the composites compared to the yarn without prior thermal treatment. A Youngs’ modulus and tensile strength of 86 ± 11 GPa and 1181 ± 71 MPa respectively are achieved in thermoset composites based on the developed yarns.

A new prototype reactor for the fast microwave-assisted decarboxylation and extraction of cannabinoids in olive oil from Cannabis inflorescences

Several different Cannabis-based pharmaceutical preparations have been approved for medical treatments. Standardization to ensure specified phytocannabinoid contents and to maintain the integrity of the product is therefore required. Olive oil is clearly a safe and edible solvent suitable for the galenic preparation of ready-to-use Cannabis extracts. Pharmacists can use several non-standard procedures for this purpose, most of which involve the heat treatment of the plant matrix (i.e. the female inflorescences) for 2 h. In order to allow the “neutral” and more biologically active forms of the major phytocannabinoids to be extracted, prior thermal treatment of the plant matrix is desirable. This work investigates a new prototype microwave (MW) reactor (Ethos Lean) specifically designed for the decarboxylation of the acidic cannabinoids in Cannabis inflorescences and their subsequent extraction into oil. Both of the steps to produce the oily extract were carried out in the Ethos Lean's cavity with special accessories; a rotating drum for the decarboxylation process and a glass reactor with a stirrer for the extraction step. The variables considered in the process optimization were time and temperature, according to which the instrument automatically calibrated the power output. In collaboration with a hospital pharmacy, the efficiency of the device has been evaluated by comparing the results obtained with those of exhaustive decarboxylation in a conventional oven and ethanol extraction. A comparison was also made with conventional procedures in olive oil. Thanks to the rotating drum, which is sensitive to dielectric heating, the complete and homogeneous decarboxylation of phytocannabinoids was rapidly achieved (30 min, 120 °C), even with discrete quantities of inflorescences (150 g) and without releasing the characteristic intense odor into the laboratory. The exhaustiveness (100% yields of both CBD and THC) of MW-assisted extraction process in olive oil was achieved with 30 min irradiation at 90 °C. Furthermore, the possible decarboxylation occurring during MW-assisted extraction in oil and the effect of cooling time on the final yields have also been evaluated.

Room temperature deposition of freestanding BaTiO3 films: temperature-induced irreversible structural and chemical relaxation

The room temperature aerosol deposition method is especially promising for the rapid deposition of ceramic thick films, making it interesting for functional components in energy, mobility, and telecommunications applications. Despite this, a number of challenges remain, such as an enhanced electrical conductivity and internal residual stresses in as-deposited films. In this work, a novel technique that integrates a sacrificial water-soluble buffer layer was used to fabricate freestanding ceramic thick films, which allows for direct observation of the film without influence of the substrate or prior thermal treatment. Here, the temperature-dependent chemical and structural relaxation phenomena in freestanding BaTiO3 films were directly investigated by characterizing the thermal expansion properties and temperature-dependent crystal structure as a function of oxygen partial pressure, where a clear nonlinear, hysteretic contraction was observed during heating, which is understood to be influenced by lattice defects. As such, aliovalent doping and atmosphere-dependent annealing experiments were used to demonstrate the influence of local chemical redistribution and oxygen vacancies on the thermal expansion, leading to insight into the origin of the high room temperature conductivity of as-deposited films as well as greater insight into the influence of the induced chemical, structural, and microstructural changes in room temperature deposited functional ceramic thick films.Graphical abstract

Water treatment sludge as precursor in non-dehydroxylated kaolin-based alkali-activated cements

Cement industry production and its materials demand are growing every year, leading to a CO2 and energy footprint increase. The drinking water production is increasing in water treatment plants due to the population growth, raising in turn the waste materials produced. Since these wastes are mainly managed in landfills, this preliminary research work is focused on providing a new sustainable option for valorisation processes, based on the environmental demand of the cement industry. Alkali-activated cements (AACs) can become a proper option to give the water treatment sludge a new life cycle, as they can compete with ordinary Portland cement (OPC) both in properties and sustainability. The main purpose of this study was to evaluate and formulate different AACs based on the use of both raw clay and the water treatment sludge (WTS), as precursors. The raw clay was used without previous thermal dehydroxylation treatment, and the WTS, an aluminosilicate-rich waste, was used partially replacing the raw clay in the AACs formulations. Both precursors and the formulated AACs were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF) and Fourier-transformed infrared spectroscopy (FT-IR). In addition, the compressive strength, the chemical stability (hydrolytic degradation), and the environmental impact for each AACs formulation were also determined. The results showed that AACs specimens formulated with 20 wt% of WTS (replacing the raw clay) provided the best results, considering both compressive strength and resistance to hydrolytic degradation. Then, it is possible to formulate AACs using raw clay, without prior thermal dehydroxylation treatment, and WTS as precursors.

Thermal Treatment Options for Benign Thyroid Nodules—The Role of Radio-Frequency Ablation and Laser Therapy

Thermal Treatment Options for Benign Thyroid Nodules—The Role of Radio-Frequency Ablation and Laser Therapy

Oleogelation of rapeseed oil with cellulose fibers as an innovative strategy for palm oil substitution in chocolate spreads

Abstract The texturing properties of mercerized cellulose dispersed in rapeseed oil without any prior thermal treatment were investigated as a function of botanical origin, cellulose content, mass fraction and fiber size through a molecular analysis of samples, macroscopic/microscopic observations and rheological experiments (continuous and oscillatory shear flows). A solid-like behavior of dispersions was demonstrated for a minimum cellulose content of about 60wt% in the vegetal powder. The oleogelation efficiency increases with the mass fraction of powder in oil and the maximum size of cellulose fibers as a result of weak attractive interactions and fiber entanglement giving rise to a network entrapping the liquid phase. An innovative strategy using a 30wt% dispersion of bamboo fibers in rapeseed oil was finally used to produce in a conch a chocolate spread with a high thermal stability at 38°C and healthier nutritional qualities compared to an equivalent product prepared with palm oil.

Adsorption Behavior of Pb(II), Cd(II), and Zn(II) onto Agave Bagasse, Characterization, and Mechanism.

Biosorption is an alternative procedure to remove metal ions from aqueous media using agricultural waste. In this work, the adsorption capacity and removal efficiency of agave bagasse (AB) toward Pb(II), Cd(II), and Zn(II) were analyzed. Parameters such as equilibrium pH, particle size, AB dosage, time, and initial metal ion concentration were discussed. The results showed that pH 5.5, 0.4 g (<250 μm), and only 15 min of contact assured conditions for maximum adsorption capacity. The kinetic studies were fitted to the pseudo-second-order model, whereas the isotherms showed good agreement with the Langmuir model. AB has a higher affinity for Pb(II) over Cd(II) and Zn(II), and the maximum adsorption capacities were 93.14, 28.50, and 24.66 mg g–1, respectively. The results of the characterization evidenced two adsorption mechanisms. Scanning electron microscopy and X-ray diffraction displayed adsorption via the ion exchange mechanism by releasing Ca(II). The 13C cross-polarization mode with magic-angle spinning nuclear magnetic resonance analysis demonstrated a complexation mechanism by cellulose, hemicellulose, and lignin groups with Pb(II) and Cd(II), whereas the complexation is mainly observed by cellulose groups for Zn(II). AB is a good alternative for the removal of metals without prior thermal or chemical treatment, with rapid kinetics, suitable adsorption capacity, and high removal efficiency contributing to waste management.

Effect of cyclic β annealing on phase evolution and lamellar boundary characteristics at surface and subsurface layers of Ti–6Al–4V alloy

The evolution of β phase and nature of α lamellar boundary in Ti–6Al–4V alloy were investigated by surface and subsurface quasi in situ EBSD measurements after repeated β zone annealing. Multi-variant distribution of α lamellae within single prior β grain matrix was also discussed. Oxygen desorption from alloy surface led to retention of 14% β phase, which affected lamellar boundary misorientation characteristics. Fraction of sub-boundaries (misorientation angle < 5°) substantially increased after the first surface reconstruction process. Boundary character involving considerable length fraction of Σ13b type interface characterised by 57.50°/<112‾0> was found after each thermal treatment, analogous to the formation of coherent twin boundaries originating from growth accidents. It was observed that, regardless of prior thermal treatment and surface or subsurface measurement, 53% of α/α interface length misoriented over a range of 55°–65° formed Σ13b type coincidence site lattice.

Coupled heat and mass transfer modelling in convective drying of biomass at particle-level: Model validation with experimental data

Acai berry waste (13.40 mm diameter, 1250 kg m−3 specific mass, 1850 J kg−1 °C−1 specific heat and 0.91 sphericity) is a large-scale agroindustrial by-product that can be used as source of biomass for thermochemical conversion. As this material has high initial moisture content, prior thermal treatment using drying is necessary. In this work, mathematical modelling of the single particle drying kinetics of acai berry waste was performed. The experimental conditions were: temperature of 42 °C and 57 °C and gas velocity of 1.8 m·s−1. Non-isothermal model consisted of differential equations based on macroscopic energy balance and on the differential form of the analytical solution of the diffusive model. The estimated values of h were 47.78 W·m−2·°C−1 at 42 °C and 42.55 W·m−2·°C−1 at 57 °C and for D0 and Ea were 1.39 × 10−4 m2·min−1 and 26.88 kJ·mol−1 at 42 °C, respectively, and 2.94 × 10−4 m2·min−1 and 25.05 kJ·mol−1 at 57 °C, respectively. The optimum value of Bim was equal to 2.5. The results showed that the non-isothermal model gave good predictions for both temperature and moisture content of the solid during drying. It was verified that there was not a significative dependence of the moisture diffusion with the heating rate of the solid.

Structure-property-function connections underlying performance of polybenzoxazole membranes derived from BisAPAF polyimides

Polymeric membranes remain and will most likely continue to be the most practical cost-effect chemical constructs for gas separation processes, provided that novel polymers are developed to overcome current and persisting limitations facing exiting membranes. Here, we report a methodical and systematic study of the structure-property-function relations of standard polyimide membranes and their implications on the separation performance. Three different dianhydrides (PMDA, ODPA and BTDA) with a single diamine (BisAPAF) were used to synthesize polyimide membranes via azeotropic imidization. The membranes were characterized, thermally rearranged and tested using gas pairs. Characterization was conducted prior and post thermal treatments in order to investigate the influence of the chosen precursors on the ideal selectivity properties. The resulted molecular weights of the polyimides were determined to be between 25,000 and 94,000 g/mol. The glass transition temperatures varied between 220 °C and 270 °C, and the degradation temperatures were at an average of 550 °C. The gas separation performance of all membranes significantly improved post thermal rearrangement, especially the APAF-BTDA polyimide which surpassed the so-called selectivity/permeability upper bound for CO2/CH4, N2/CH4 and CO2/N2 gas pairs.

Effect of ultrasound on the structure and functional properties of transglutaminase-crosslinked whey protein isolate exposed to prior heat treatment

Effects of ultrasound treatment (20 kHz, 41–45 W cm−2, 0, 20, 40 or 60 min) on the physicochemical, functional properties and elements of the secondary structure of transglutaminase (TGase)-crosslinked whey protein isolate (WPI) exposed to prior thermal treatment (75 °C, 15 min) were investigated. The largest molecular size of proteins in the TGase-crosslinked WPI was observed after the ultrasound and thermal pre-treatment (HU-WPI-TGase). HU-WPI-TGase had the maximum intrinsic fluorescence intensity, with highest loss of free amino groups. Ultrasound-treated WPI (U-WPI) showed more (13%) emulsifying activity and more (63%) foaming ability than untreated WPI, but HU-WPI-TGase had higher foam stability and lower emulsifying activity than U-WPI. FTIR analysis indicated that ultrasound, heat treatment and TGase cross-linking had effects on the β-sheet, β-turn and random coil of WPI. The outcomes from this study show a potential application in providing novel functional ingredients for the dairy industry.

Antioxidant activities of hydrolysed collagen from salmon scale ossein prepared with the aid of ultrasound

SummaryHydrolysed collagen with antioxidant activity from salmon scale ossein as influenced by ultrasound pretreatment and prior thermal treatment were investigated. Ultrasound pretreatment of scale ossein at 70% amplitude for 30 min with intensity power of 750 W, followed by heating at 55 °C for 6 h resulted in the highest release of collagenous materials from ossein. Hydrolysed collagen from aforementioned scale ossein prepared using Alcalase had higher degree of hydrolysis and recovery than those from ossein with other pretreatments. 2,2′‐Azinobis(3‐ethylbenzothiazoline‐6‐sulphonic acid) (ABTS), 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activities and ferric reducing antioxidant power (FRAP) increased as Alcalase concentration increased. Higher proportion of low molecular weight (MW) peptides was observed after gastrointestinal digestion, in which peptides with MWs of 347 and 219 Da exhibited the highest ABTS radical scavenging activity and FRAP, respectively. Therefore, ultrasound pretreatment of ossein along with subsequent thermal treatment could increase yield and antioxidant activities of hydrolysed collagen.

Investigation of the effects of thermal treatment on the leachability of Zn and Mn from discarded alkaline and Zn[sbnd]C batteries

Spent alkaline and ZnC batteries are a potential source of Zn and Mn. This study reports on the effects of thermal treatment on the leachability of metals from such products. Black mass originating from alkaline and ZnC batteries was thermally treated under four different atmospheres: O2, N2, H2 and air at different temperatures (300–950 °C). Samples without prior thermal treatment and solid residues after thermal treatment were subsequently leached with H2SO4. Leaching of the samples without the thermal treatment was done to determine the reference leaching conditions, which were established to be 0.5 M H2SO4 at 25 °C for 60 min. Subsequently, samples which had been thermally treated were leached using the aforementioned reference conditions. The effect of thermal treatment on the leaching of Mn and Zn was studied to determine which conditions may improve or hinder subsequent hydrometallurgical processing of alkaline batteries. The use of O2 during the thermal treatment led to formation of ZnMn2O4, which inhibited effective leaching. ZnMn2O4 was decomposed in N2 atmosphere and in the presence of C, improving further dissolution of Mn. The use of H2 led to formation of Mn3O4. This compound showed low dissolution, being possible to be separated from impurities such as Fe, Ni and K by leaching with 0.5 M H2SO4. To increase the purity of recovered Mn3O4, oxalic acid was used as reduction agent. A final solid product, Mn3O4, with a purity of 99.95%, was obtained. Data provided by this research can lead to improvements of existing recycling processes, allowing for higher leaching efficiency of alkaline and ZnC battery materials. Also, overall material recovery rates can be increased by producing manganese oxide with high purity.

Spark Plasma Sintering of a Hard Metal Powder Obtained from Hard Metal Scrap

Spark plasma sintering is used to consolidate a WC-Co powder produced from milled discharged hard metal cutting inserts. The powder was mixed to 10%wt Co powder and spark plasma sintered (SPS) under 80Mpa pressure, at 1200oC with heating rate of 160oC/min. A reference alloy was prepared with a commercial WC powder and 10%wt. Co under the same conditions. The structures of both alloys were investigated by means of scanning electron microscopy and Vickers hardness. The results show structures with densities and hardness at the same level. SPS can be used to produce hard metal pieces directly from scrap powder without any prior chemical and thermal treatment.

A single stranded fluorescent peptide probe for targeting collagen in connective tissues.

We herein report the construction of a novel single stranded fluorescent collagen mimetic peptide by introducing a bulky FAM dye in the central region rather than the N terminus. Without the need for any prior thermal or ultraviolet treatment, the peptide probe can be conveniently applied to specifically target collagen in connective tissues for fluorescence imaging.

In vitroActivities of the Four Structurally Similar Flavonols Weakened by the Prior Thermal and Oxidative Treatments to a Human Colorectal Cancer Line

Four structurally similar flavonols galangin, kaempferol, morin and myricetin in solutions were heated at 100C for 30 min or oxidized by air for 6 h, and then assessed for in vitro activities to human colon cancer cells (HCT-116) in terms of anti-proliferation, apoptosis induction, intracellular reactive oxygen species (ROS) generation and mitochondrial membrane potential loss. The oxidized and especially heated flavonol solutions showed degradation with decreased violet absorption, and the four flavonols and treated flavonols all could induce the cells with apoptotic morphology. Other results indicated that galangin with less −OH in its molecules had the highest activities to the cells, followed by morin, kaempferol and myricetin with increased −OH numbers in their molecules. The oxidized and especially heated flavonols always showed weaker anti-proliferation, apoptosis induction, ROS generation and membrane disruption than native flavonol counterparts, demonstrating adverse effects of the thermal and oxidative treatments on these anti-cancer activities of flavonols. Practical Applications In this study, the four flavonols were proved to have anti-cancer activities to human colon cancer HCT-116 cells shown as growth inhibition, apoptosis induction, membrane disruption, and enhancement of ROS generation. However, oxidative and especially thermal treatments of the flavonols were observed to decrease these activities. The results demonstrate an important conclusion that improperly and excessive heating and storage of plant foods might induce flavonol (or flavonoid) degradation, and thus bring about adverse effects on anti-cancer properties of plant foods. The effects of other treatments on anti-cancer properties of flavonoid or plant foods containing them are suggested for further investigation.

Simultaneous improvements of the strength and ductility of fine-grained AA6063 alloy with increasing number of ECAP passes

In this research, grain refinement through severe plastic deformation (SPD) in combination with a thermal treatment to create a fine initial grain structure with a high degree of supersaturation was taken as a viable approach to achieving simultaneous increases in the hardness, strength and ductility of the aluminum alloy AA6063 during further SPD. A recrystallized structure with grain sizes around 20µm was obtained after two passes of equal channel angular pressing (ECAP), followed by a thermal treatment at 500°C for 10s and water quenching. The alloy with the supersaturated α-Al matrix was subjected to further ECAP processing up to six passes to create a cellular structure on a nano scale. Hardness and tensile tests revealed the changes of hardness, strength and ductility along with increasing number of ECAP passes. It was found that after two ECAP passes, the ductility of the alloy decreased from the value after the prior two-pass ECAP and thermal treatment. However, by further ECAP processing up to six passes, the ductility increased along with the increases in hardness and strength. The remarkable improvement in ductility was attributed to a nanosized cellular structure with a large area of high-angle grain boundaries developed from the fine initial grain structure formed during the two-pass ECAP and thermal treatment applied earlier.

Scaling Effects on Color and Transparency of Multilayer Polyethylene Films in Polarized Light

AbstractTransparency and color of polyethylene film layered packages change with the number of layers. When polyethylene layer thickness is between 50 μm and 200 μm, each additional subsequent layer in the package leads to an abrupt change in color and transparency. Polarized light optical effects can be used to manufacture packaging films and labels with forgery protection. A significant influence of the scaling factor on the latent effect and optical properties of the film package is demonstrated for one to six layers with the total thickness of 200 ± 50 μm. Prior thermal treatment of individual layers before they are assembled into a package or assembled package heat treatment change the laminate color. This allows hidden marking and recording text or graphics on the multi‐layer films, not visible under normal lighting conditions, but appearing when viewed in polarized light, or through the polarizer. The paper demonstrates obtaining bright colored decorative or packaging materials, along with light filters for advertising and information displays, which change color with the viewing angle. New materials can be prepared using standard industrial equipment and widely used polymers. By changing the location of the film polarizers, the number of layers and the film thickness, laminates vary in brightness and color from blue to red.