Increasing Processing Temperature Research Articles

ECOLOGICAL FEATURES OF SOAKING AND ASH PROCESSES IN THE PRODUCTION OF LEATHER

Ecological and colloid-chemical features of soaking-ash processes in processing of raw cattle leather materials at production of elastic leather for uppers of footwear according to operating and developed resource-saving technologies are investigated. To evaluate the effectiveness of the technological processes used a set of physic-chemical and operational properties of leather semi-finished products at different stages of its formation to the finished material. Resource-saving ecologically oriented technology of soaking and ash processes in leather production for shoe uppers from raw salted conserved materials – bull skins has been developed. Physicochemical, technological and ecological features of existing and developed technologies are studied. The developed technology due to the increase of process temperature provides more efficient use of chemical reagents, reduction of concentrations of environmentally hazardous reagents, process duration and energy consumption per unit of output. At the same time, the total consumption of chemical reagents is reduced by 2.2 times, and in the waste technological solutions the concentration of sodium sulfide and calcium hydroxide – by 2.9 and 4.4 times, respectively. However, the developed resource-saving environmentally friendly technology is characterized by a reduction in biological and chemical oxygen demand for the destruction of organic and inorganic substances in the waste soaking-ash solution after treatment of 1 ton of raw materials by 30.0 and 21.0%, respectively. By reducing the duration of the technological process by 2.3 times, the new technology can be considered as energy efficient. The developed resource-saving technology provides the formation of leather material for shoe uppers with an increased yield of 3.9%, and its performance properties meet the requirements of DSTU 3115-95. The results obtained in the development of environmentally friendly resource-saving technology of soaking ash processes for footwear leather uppers from raw cattle leather materials can be effectively used in the development of new innovative technologies for the manufacture of leather materials from a wide range of other raw materials.

Hydrochars produced by hydrothermal carbonisation of seaweed, coconut shell and oak: effect of processing temperature on physicochemical adsorbent characteristics

The present study addresses the production of hydrochars from brown seaweed (Fucus serratus) (FS-HCs), coconut shell (CS-HCs), and oak (Oak-HCs) as potential adsorbents using hydrothermal carbonisation (HTC). The effect of HTC processing temperature on the physicochemical adsorbent characteristics of the hydrochars is investigated at different temperatures (200, 220, 250 °C) using a hydrothermal batch reactor. Increasing HTC temperature causes the formation of many spheres in CS-HCs and Oak-HCs, increasing their porosity, except FS-HCs. The surface area of the hydrochars increases with increasing HTC temperature; 10.93–12.78 m2/g for FS-HCs, 2.18–21.94 m2/g for CS-HCs, except for Oak-HCs which decreases from 4.89 to 3.09 m2/g. Increasing HTC temperature decreases volatile matter content in the hydrochars, increases fixed carbon content, and decreases H/C ratio (except for FS-HCs) and O/C ratio of the hydrochars. For all the hydrochars, increasing the HTC temperature results in a slight decrease in zeta potential magnitude, with negatively charged surfaces, making them potential adsorbents for cationic pollutants. The study confirms that the HTC process improves key chemical and physical characteristics of the hydrochars compared to the original biomass, and that the physicochemical adsorbent characteristics are enhanced as the processing temperature increases.

Thermal, morphological, rheological and deformation under mechanical loading analyses of recycled polyethylene terephthalates

Abstract This study aims at determining the mechanical deformation behavior of recycled poly (ethylene terephthalate) (r-PET) with digital image correlation (DIC) and finite element method (FEM), and to investigate the morphological, thermal, and rheological properties of r-PETs. Waste bottles were collected in trash bins and granulated with a cutter. Neat PET (n-PET) was also was used to determine accurately the changes in the properties of r-PET. PET test samples were obtained by injection molding at 260, 265, 270, and 275 °C. DIC and FEM were conducted to detect the deformation behavior of the PETs under mechanical loading. The data showed that the behavior of n-PETs and r-PETs were similar, and the stress distribution was found to densify in various areas for both PETs. The mechanical properties generally increased with increasing processing temperature, the best mechanical properties being obtained for thPETs processed at 275 °C. Scanning electron microscopy (SEM) analysis showed that the morphology of all the PETs were similar. Thermal stability was also found to be similar. The rheological moduli of n-PET processed at 260 °C were the highest, while processing r-PET at 275 °C improved its rheological properties.

Effects of biochar produced from tropical rice straw, corncob, and bamboo tree at different processing temperatures on in vitro rumen fermentation and methane production

This study aimed to evaluate the effects of biochar produced from tropical biomass resources (rice straw, corncob, and bamboo) at different processing temperatures (300, 500, and 700 °C) on in vitro rumen fermentation and methane production. Treatments were arranged as a 3 × 3 factorial design with three biomass resources and three biochar processing temperatures. Added biochar occupied 3% of the substrate (DM basic). Two hundred fifty milligrams of the air-dried substrate was incubated in 120 ml bottles, which contained 25 ml of mixed rumen fluid and buffer mineral solution. Total gas and methane production, in vitro digestibility of DM and OM, and in vitro rumen fermentation characteristics were determined at three time points of 4, 24, and 48 h of the incubation. The results showed that biomass resources and processing temperatures affected gas production at 4, 24, and 48 h after incubation (P < 0.01). Interactions between biomass resources and processing temperatures affected gas production at 4 h (P = 0.06) and 24 h (P = 0.001). Biomass resources and processing temperatures affected methane production at different time points of the incubation (P < 0.05), except the effect of biomass resources at 24 h (P = 0.406). Increased processing temperature from 300 to 700 °C reduced gas and methane production (P < 0.05). Biomass resources affected OM digestibility after 4 and 24 h of incubation. Processing temperatures and their interaction with biomass resources affected OM digestibility after 48 h of incubation (P < 0.001). NH3-N concentrations at 24 and 48 h were highest for corncob, then rice straw, and lowest for biochar derived from bamboo tree (P < 0.05). Increased processing temperatures resulted in higher NH3-N concentrations at 24 and 48 h of incubation (P < 0.05). To mitigate methane production, biomass resources and processing temperatures should be considered when using biochar as a feed additive in ruminant diets.

Temperature influence on the triboelectric powder charging during dry coating of polypropylene with nanosilica particles

The influence of process temperature on the triboelectric charge during dry coating of cohesive polymer powders is investigated. The purpose of heating is to decrease the surface moisture of the powder, which results in an increase of electrical charge of the powder. The effect of the hydrophilicity of the SiO2 guest particles on the quality of the dry coating of PP host particles was investigated with respect to the integral charge of the dry coated powder. Furthermore, the flowability, crystallization behavior and degree of coverage (DOC) were investigated to determine the influence of the increased charge on these topics. Increased process temperature increases the electrical charge of the powder, which leads to a higher DOC with guest particles and, thus, drastically improved flowability compared to dry coating at ambient temperature. Furthermore, changes in the crystallization behavior of polypropylene are observed, due to more nuclei.

Pyrolysis of Tibetan Yak Dung for Producing Biochar Pertinent to Agro-environmental Application

ABSTRACT The study was investigated the influence of pyrolysis conditions on the yield and nutrient properties of yak dung-based biochar and its potential of agro-environmental applications. A series of biochars were made by hydrothermal carbonization (HTC) under the different atmospheres, such as Nitrogen (N2) and carbon dioxide (CO2), processing temperatures (200-300 °C) and residence times (1-2 h). The results showed the yield of yak dung-based biochar ranges from 35.33 wt% to 58.29 wt%. The concentration of nitrogen (N), phosphorus (P) and potassium (K) in biochar varied from 28.18 mg·g−1 to 15.54 mg·g−1, 16.23 mg·g−1 to 25.31 mg·g−1 and 0.59 mg·g−1 to 1.02 mg·g−1, respectively. And the contents of micronutrients Zn and Fe varied from 4.6 mg·g−1 to 17.42 mg·g−1, and 15.28 mg·g−1 to 29.22 mg·g−1, respectively. The yield, total carbon (C), N, hydrogen (H) and oxygen (O) content of biochar decreased with increasing processing temperature, while the total P and K content, pH and Brunauer-Emmett-Teller (BET) surface area increased; moreover, the P and K content of biochar produced in N2 increased more compared with CO2. The heavy metal contents of copper (Cu), cadmium (Cd), chromium (Cr), platinum (Pb) and arsenic (As) all were lower in yak dung-based biochar compare with other manures or sewage sludge-based biochar. Biochar produced in N2 had higher nutrient content indicating the potential of application for fertilizer compared with it in CO2; while the biochar produced in CO2 with larger surface area characteristic and more abundant functional groups showing higher potential of application for the soil amendments and nutrient control materials. Our study provides some new insights for biochar production according to its application.

Microstructural evolution of Al-7.3Zn-2.2Mg-2Cu (Al7068) alloy in T6 condition during isothermal compression using 3-dimensional processing map

Elevated temperature isothermal compression of Al-7.3Zn-2.2Mg-2Cu (Al7068) alloy in T6 condition was studied till a true strain of 0.69 in the working temperature and deformation rate range of 250–450 °C and 0.001–1 s−1, respectively. The rheological behaviour of the specimens showed a decrease in the flow stress values at the higher temperature and lower strain rates. The mean deformation activation energy at peak stress was estimated as 266 kJ/mol. 3D processing map suggested two safe working zones (I and II) for the current alloy. Zone I, with a peak efficiency of 57% located in the domain of 288–312 °C at 0.001 s−1, and zone II with an efficiency ≥ 48% located in the range of 400–450 °C and 0.001–0.044 s−1. The EBSD IPF micrograph of the compression specimens showed a dominance of deformed grains with few fine DRX grains near the grain boundary regions. The analysis showed that the microstructural evolution during hot compression progressed through the CDRX mechanism. TEM analysis confirmed precipitate coarsening with increase in processing temperature and decrease in the deformation rate.

Experimental Investigation of the Interlaminar Failure of Glass/Elium® Thermoplastic Composites Manufactured With Different Processing Temperatures

The aim of this study is to evaluate the effect of the processing temperature on the interfacial failure of glass/Elium® 150 composites. The vacuum assisted resin transfer molding technique (VARTM) was used to manufacture glass/Elium® 150 composites at three different process temperatures: room temperature (24℃), 50℃ and 80℃. The interlaminar shear strength, mode I and mode II interlaminar fracture toughness of the laminates were determined by performing the short beam shear (SBS), double cantilever beam (DCB) and end notched flexure (ENF) tests, respectively. It was found that the increase in processing temperature improved the interlaminar shear strength, mode I and mode II interlaminar fracture toughness by approximately 41%, 66% and 227%, respectively. A combined compressive and shear failure mode was found in SBS tests. Fiber bridging was present for all the composite specimens in DCB tests according to the travelling recording camera images. Fracture surface images obtained by scanning electron microscopy (SEM) after the ENF tests revealed that a better fiber-matrix bonding and a ductile matrix failure were obtained for higher processing temperatures.

Hierarchically porous and mechanically stable monoliths from ordered mesoporous silica and their water filtration potential.

Mechanically stable structures with interconnected hierarchical porosity combine the benefits of both small and large pores, such as high surface area, pore volume, and good mass transport capabilities. Hence, lightweight micro-/meso-/macroporous monoliths are prepared from ordered mesoporous silica COK-12 by means of spark plasma sintering (SPS, S-sintering) and compared to conventionally (C-) sintered monoliths. A multi-scale model is developed to fit the small angle X-ray scattering data and obtain information on the hexagonal lattice parameters, pore sizes from the macro to the micro range, as well as the dimensions of the silica population. For both sintering techniques, the overall mesoporosity, hexagonal pore ordering, and amorphous character are preserved. The monoliths' porosity (77–49%), mesopore size (6.2–5.2 nm), pore volume (0.50–0.22 g cm−3), and specific surface area (451–180 m2 g−1) decrease with increasing processing temperature and pressure. While the difference in porosity is enhanced, the structural parameters between the C-and S-sintered monoliths are largely converging at 900 °C, except for the mesopore size and lattice parameter, whose dimensions are more extensively preserved in the S-sintered monoliths, however, coming along with larger deviations from the theoretical lattice. Their higher mechanical properties (biaxial strength up to 49 MPa, 724 MPa HV 9.807 N) at comparable porosities and ability to withstand ultrasonic treatment and dead-end filtration up to 7 bar allow S-sintered monoliths to reach a high permeance (2634 L m−2 h−1 bar−1), permeability (1.25 × 10−14 m2), and ability to reduce the chemical oxygen demand by 90% during filtration of a surfactant-stabilized oil in water emulsion, while indicating reasonable resistance towards fouling.

HYDROTHERMAL EXTRACTION OF LITHIUM COMPOUNDS FROM PETALITE Li[AlSi4O10

Based on studies of the decomposition of pe­ta­lite ore, the hydrothermal method for the extraction of lithium and aluminum compounds from lithium aluminosilicate Li[AlSi4O10] (petalite) has been developed. The studied sample of ore contains, wt. %: Li2O – 0.75 and Al2O3 – 14.65. For unenriched petalite ore with low lithium content, it is proposed to use the hydrochemical method of aluminosilicate processing – Ponomarev – Sazhin method. According to this method, the decomposition of ore is carried out directly in autoclaves by chemical interaction of ore components with NaOH solution in the presence of calcium oxide. The conditions (high temperature and pressure) for the destruction of petalite and the transition of lithium into the liquid phase are created exactly in the hydrothermal process. In this case, lithium and aluminum compounds pass into the solution, and calcium and silicon form a partially soluble compound in the solid phase – sodium-calcium hydrosilicateNa2O·2CaO·2SiO2·2H2O. The degree of extraction of lithium reaches 89–94 %, aluminum reaches 77–95 % within 1 hour at a tempe­rature of 240–280 °C, given caustic modulus 14–18, the concentration of the initial solution of 400–450 g/dm3 of Na2O and the ratio of CaO : SiO2 = 1 : 1 in the reaction mixture. Aluminate or lithium carbonate and other compounds can be obtained from an aluminate solution containing 1.5–2.5 g/dm3 of Li2O and 32–44 g/dm3 of Al2O3. The solid phase formed as a result of decomposition, with a high degree of extraction of lithium from the ore contains a small amount of Li2O in its composition and therefore can be used in the cement industry.&#x0D; Depending on the quality of the decomposed raw material, the course of the hydrothermal process is influenced by a set of factors. With a small content of lithium and aluminum in the ore, the caustic modulus of aluminate solutions (αк = 1,645*Na2O/Al2O3) formed after decomposition is important. Its calculation is required in order to determine the amount of alkaline solution of the required concentration to ensure almost complete decomposition of the ore. This value should be higher the lower the decomposition temperature and the concentration of the initial solution to achieve the same degree of recovery of useful components in the liquid phase. With the same caustic modulus, the efficiency of ore decomposition increases significantly with increasing process temperature and increasing the concentration of the initial solution. This can be seen in the values of the degree of extraction of aluminum, which increases by 12 % with increasing temperature from 240 to 280 °C, while the extraction of lithium remains practically unchanged.

Influence of temperature on slow pyrolysis of Prosopis Juliflora: An experimental and thermodynamic approach

In this study, the slow pyrolysis of Prosopis Juliflora was performed to determine the product yield distribution and its physiochemical properties, thermodynamic and sustainability performance of a process. Findings indicate that the increase in process temperature (300–600 °C) negatively impacted biochar yield while positively affected bio-oil and pyrolysis gas yield. The HHV, fixed carbon and fuel ratio of biochar was improved at higher pyrolysis temperature while energy yield decreased. The maximum bio-oil yield was obtained at 500 °C, and it contains a high fraction of phenolic compounds (35.54%) followed by aromatics (23.01%). The concentration of H2 (7.21–19.88%) and CH4 (1.89–2.59%) and Py-gas heating value (4.98–7.89 MJ Nm−3) improved with an increase in process temperature.The pyrolysis system's energy (76.97–84.54%) and exergy efficiency (67.41–83.38%) were enhanced with process temperature, and the GRA optimization was attained at 600 °C. The sustainability index, environmental factor, and improvement potential positive impact the environment at a higher temperature. It is recommended to produce superior quality of biochar, bio-oil and Py-gas in the temperature range of 500–600 °C with minimal environmental impact.

Characterization of Bio-Adsorbents Produced by Hydrothermal Carbonization of Corn Stover: Application on the Adsorption of Acetic Acid from Aqueous Solutions

In this work, the influence of temperature on textural, morphological, and crystalline characterization of bio-adsorbents produced by hydrothermal carbonization (HTC) of corn stover was systematically investigated. HTC was conducted at 175, 200, 225, and 250 °C, 240 min, heating rate of 2.0 °C/min, and biomass-to-H2O proportion of 1:10, using a reactor of 18.927 L. The textural, morphological, crystalline, and elemental characterization of hydro-chars was analyzed by TG/DTG/DTA, SEM, EDX, XRD, BET, and elemental analysis. With increasing process temperature, the carbon content increased and that of oxygen and hydrogen diminished, as indicated by elemental analysis (C, N, H, and S). TG/DTG analysis showed that higher temperatures favor the thermal stability of hydro-chars. The hydro-char obtained at 250 °C presented the highest thermal stability. SEM images of hydro-chars obtained at 175 and 200 °C indicated a rigid and well-organized fiber structure, demonstrating that temperature had almost no effect on the biomass structure. On the other hand, SEM images of hydro-chars obtained at 225 and 250 °C indicated that hydro-char structure consists of agglomerated micro-spheres and heterogeneous structures with nonuniform geometry (fragmentation), indicating that cellulose and hemi-cellulose were decomposed. EDX analysis showed that carbon content of hydro-chars increases and that of oxygen diminish, as process temperature increases. The diffractograms (XRD) identified the occurrence of peaks of higher intensity of graphite (C) as the temperature increased, as well as a decrease of peaks intensity for crystalline cellulose, demonstrating that higher temperatures favor the formation of crystalline-phase graphite (C). The BET analysis showed 4.35 m2/g surface area, pore volume of 0.0186 cm3/g, and average pore width of 17.08 μm. The solid phase product (bio-adsorbent) obtained by hydrothermal processing of corn stover at 250 °C, 240 min, and biomass/H2O proportion of 1:10, was activated chemically with 2.0 M NaOH and 2.0 M HCl solutions to investigate the adsorption of CH3COOH. The influence of initial acetic acid concentrations (1.0, 2.0, 3.0, and 4.0 mg/mL) was investigated. The kinetics of adsorption were investigated at different times (30, 60, 120, 240, 480, and 960 s). The adsorption isotherms showed that chemically activated hydro-chars were able to recover acetic acid from aqueous solutions. In addition, activation of hydro-char with NaOH was more effective than that with HCl.

Preparation and characterization of carbon black (CB) using heavy residue fraction of spent tyre pyrolysis oil

In the interest of utilisation of industrial waste products, this paper investigated the preparation and characterization of carbon black (CB) made via partial oxidation of a heavy residue fraction (HRF) of spent tyre pyrolysis oil in a drop tube furnace. The effect of process temperature, residence time (Rtime), and O2 concentration on the yield and quality (elemental composition, functional groups, morphology, thermal behavior, and surface area) of HRF-CB were determined using elemental analyzer (EA), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), thermogravimetric analyzer (TGA), and Brunauer-Emmett-Teller (BET) nitrogen adsorption/desorption technique. Higher temperatures led to higher yields (41–60%) and better quality of the resultant CB. Above 1150 °C, the CB samples were comparable with commercial CB products, with low ash (<0.1%), low volatile matter (<6.1%), moderate BET surface area (11–24.2 m2g−1), and high C contents (~94–99%). Quality was also improved as Rtime or O2 increased but at some sacrifice to the total yield. HRF-CB aggregates were morphologically complex, highly structured and had good thermal stability, which increased with increasing process temperature, Rtime and O2 concentration, respectively. Interestingly, the hydroxyl, carbonyl and carboxyl surface groups in the HRF-CB were higher (54 – 69%) than commercial products (0–59%) under all process conditions, which is a desirable trait for enhanced bonding and mechanical properties but typically introduced to commercial CB by secondary procedures. Given their comparable properties, CB from heavy residues of spent tyre pyrolysis oil may be a suitable replacement for commercial CBs used in rubber reinforcement.

Suitability of rice straw for biochar production through slow pyrolysis: Product characterization and thermodynamic analysis

The main objective of the present study is to turn the wheel from waste to wealth by sustainable rice straw management practices over field burning in India. For that, slow pyrolysis of rice straw was carried out in a fixed bed reactor. The result indicated an increase in process temperature (300–600 °C) led to the decreased biochar yield, while pH (8.28–11.4), pore-volume (0.0087–0.059 cm3/g), surface area (12.78–83.06 m2/g), and HHV (17.63–20.13 MJ/kg) of biochar increased. The maximum bio-oil yield was obtained at 500 °C, and its characterization study indicated a high amount of phenol and aromatic compounds. The composition of H2 (1.9–17.72%) and CH4 (2.3–8.82%) in the gas and heating value (6.5–9.4 MJ/Nm3) of the gas increased with temperature. The energy (84.22–89.61%) and exergy efficiency (74.41–87.37%) of the pyrolysis system increased with process temperature, and the thermodynamic optimization was achieved at 600 °C.

Thermal destruction of polymers: analysis of the process physicochemical parameters

This experimental study has confirmed that during thermal decomposition of polymeric waste samples at a temperature of 850 °C, without oxygen access, there is a 90 % drop in the mass of this waste with the release of a large volume of gaseous products. This feature should be taken into consideration in the engineering calculations of reaction chambers, reactors, and connecting gas pipelines. The analytical study was carried out by a method of thermodynamic analysis using the universal estimation system Astra (TERRA). It has been shown that with an increase in reaction temperature there is a change in the composition of the products of thermal destruction of polymeric waste by reducing the mole fraction of СН4 and increasing the proportion of Н2. The calorific value was calculated according to Mendeleev’s empirical formula. The experimental study (a pyrolysis-gas chromatography method) has confirmed the calculation results regarding an increase in the proportion of hydrogen in the gaseous products of destruction with an increase in process temperature. As a result, due to the lower volumetric heat of hydrogen combustion, the total caloric content of the synthesis gas obtained is significantly reduced. For the experiments, a laboratory installation of low-temperature pyrolysis of polymers with external supply of thermal energy was built, and synthesis gas was used as an energy carrier. At the experimental-industrial installation, by a low-temperature pyrolysis method, the synthesis gas of a stable composition with a lower heat of combustion of 24.8 kJ/m3 was obtained. The reliability of the results of the proposed estimation method to the results of instrumental measurements has been shown. Promising areas of further studies have been determined, including the optimization of processes of thermal destruction of chlorine-containing polymer waste; the effective use of hydrogen from the composition of the synthesis gas obtained.

Influence of processing methods on quality and stability of silver catfish (Chrysichthys nigrodigitatus)

The study assessed different processing methods (freezing, smoking, oven drying and boiling) on fillet nutritional quality and stability of silver catfish. All analyses followed standard procedure. Results of proximate composition showed significant increase (p&lt; 0.05) in protein (51.98%), lipid (11.65%), ash (3.82%) and calorie (432.57 Kcal/g) contents in the dried fillets. Thus, these variable increased with increasing processing temperature. On the other hand, moisture and carbohydrate contents decreased with temperature. The stability indices showed significant differences (p &lt; 0.05) in free fatty acid of frozen (0.21%), boiled (0.8%), smoked (2.96%) and dried (9.87%). The lowest calcium (39.7%) was recorded in the frozen sample while the highest level (53.12%) in oven dried. Thiobarbituric acid decreased with increase in processing temperature with the highest level (27.14 mg MDA/100g) observed in the frozen fillet while the least value (2.08 mg MDA/100g) was obtained in the boiled samples. Calcium and phosphorus contents did not show any particular trend. The smoked fish fillet had the highest fibre content of 2.6%. Total volatile base nitrogen was generally low in all treatments. Inference from this study revealed that differently processed Chrysichthys nigrodigitatus was a rich source of fatty acids and essential minerals being very vital to the diet of humans.

Process Dependent Strain Behaviour, Fractal Analysis, and Bonding Network of Nc-Si(SiC) Thin Films

Nanocrystalline silicon embedded silicon carbide, nc-Si(SiC) thin films were deposited on p-type silicon substrates by using a thermal chemical vapor deposition (CVD) with different process temperatures from 700 to 1000 °C. The SEM images reveal the Si particles are embedded with SiC thin films. The estimated crystallite size of nc-Si(SiC) was varied from 14 to 28 nm and 40.7 to 61 nm respectively from the Scherrer formula and Williamson – Hall formula. Similarly, the estimated lattice-strain of nc-Si(SiC) thin films from Williamson-Hall and Bragg law was varied from 0.00227 to 0.00469 and 0.000855 to 0.00574 respectively. The Raman signature at the 1346.19 cm−1, 1491.78 cm-1, and 1570.94 cm−1 bonding correspond to D, G-Si, and G peaks respectively. The estimated bandgap from Tauc’s plot of nc-Si(SiC) thin films are 3.17 to 2.87 eV respectively with increasing process temperature. The possible bonding network of core-orbital of Si(2p), C(1 s), and O(1 s) in the nc-Si(SiC) thin films have been discussed by deconvolution with the Origin 2018.

Bidirectional threshold switching in Pt/Ag:Ni(OH)2/Pt structure

In this study, an Ag-doped Ni(OH)2 (Ag:Ni(OH)2) thin film is fabricated by solution process with Ag concentration of 2% at 200 °C and applied to threshold switching selector devices. X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy analysis confirm that the matrix contains 72% Ni(OH)2 and 28% NiO, while the Ag is doped as ion state. As the processing temperature increases, the Ni(OH)2 matrix changes to NiO, and the doped Ag tends to metal state. Selector devices with Pt bottom and top electrodes were fabricated and measured. Compared with a Pt/Ag:NiO/Pt device, which shows non-volatile resistive switching characteristics, bi-directional threshold switching behavior is demonstrated in the Pt/Ag:Ni(OH)2/Pt device. The selectivity is larger than 104. The high/low resistance state cycles have been measured by half-bias pulse stimulation without obvious deterioration. Since Ag ion in Ni(OH)2 matrix shows fast diffusion, a thin Ag filament could be formed at low voltage, which then disperses and fractures after the voltage is removed. It corresponds to the main mechanism of bi-directional threshold switching. For the Pt/Ag:NiO/Pt device, the formation of thicker Ag filaments at higher electric fields leads to non-volatile resistive switching.

Investigation of the Effects of Low‐Pressure Carburizing Process Parameters on Microstructural Evolution by Means of In Situ Synchrotron X‐Ray Diffraction

In situ X‐ray diffraction experiments during low‐pressure carburizing processes are performed at the German Electron Synchrotron Facility, Beamline P07, in Hamburg, Germany, with a specially developed process chamber. Microstructural evolution is precisely analyzed based on diffraction data, and several process parameters are varied. The investigations focus on boost and diffusion steps in which carbon donor gas interacts with the hot steel surface and carbon atoms diffuse through the sample. An increased process temperature leads to higher carbon absorption during the boost step, especially at the early stages of the process. Regardless of process parameters, austenite saturation is reached in a few seconds. Therefore, longer boost step duration and/or a higher acetylene amount does not directly increase the carbon profile; instead, this would only increase the amount of carbides formed on the surface, which would contribute to the carbon profile by dissolution in the following steps. Therefore, shorter and a high number of boost steps are recommended for high efficiency. The cementite formation rate shows a similar trend with austenite saturation. It is very fast at the beginning and then stays almost constant. Therefore, introducing acetylene to the furnace after that point has no positive effect on the carburization.

Evaluation of heat treatment parameters’ effect on some physical and mechanical properties of poplar wood with multi-criteria decision making techniques

Effects of the heat treatment parameters were evaluated relative to some physical and mechanical properties of poplar wood (Populus alba L.) with use of two of the prominent multi criteria decision-making (MCDM) techniques: Entropy and The Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). To meet this objective, the test samples were heat-treated at 120, 150, 180, and 210 °C for 2 and 4 h in a laboratory-scale oven. With increasing temperature and duration, the shrinkage and swelling ratios of heat-treated samples were improved. However, the bending strength, modulus of elasticity, and compression strength generally decreased with increasing process temperature and duration. According to (MCDM) analyses, thermal modification definitely improved the physical properties of wood up to a point. Bending strength was found to be the most important determinant of heat treatment success. The other determinants were identified as swelling, compression strength, shrinkage, and modulus of elasticity, respectively. Also, the best results were obtained at 120 °C for 2 h. In general, heat treatment above 150 °C or 4 h is not recommended.