Underwent Heat Treatment Research Articles

Influence of different cooling media on morphology, mechanical and corrosion of AISI 1040 grade steel

The investigation deals with AISI 1040 grade steel used in the automobile industry in the form of axles, gears, bolts, shafts, couplings, and dowels. Machined tensile samples as per ASTM E8 standard undergone heat treatment cycle i.e. heating and soaking temperature of 750 °C and followed by controlled cooling in such as furnace cooling, air cooling, quenching in water, ice, commercially available lubricant, emulsified soluble coolant. Tensile, hardness, and corrosion tests performed on samples to assess mechanical properties and corrosion behaviour. Presence of both dimples and flakes in SEM images pertaining to as received, annealed and normalized failed tensile samples demonstrates the mixed mode (ductile–brittle) and remaining failed tensile specimens dominated with the presence of flakes, which exemplifies the brittle mode of failure. The presence of martensite in hardened samples resulted in the highest strength (990 MPa), but the same has caused an adverse effect on corrosion by favouring the formation of the galvanic couple with ferrite. In contradiction to the above, annealed samples showed better corrosion resistance (-0.22v) due to the presence of larger grain size, the lesser extent of inter-granular galvanic sites, and uniform dissolution of carbides.

The Effect of Heat Treatment on Phase Structure and Mechanical and Corrosion Resistance Properties of High Tungsten Ni-W Alloy Coating

The present study investigated the surface morphology, phase composition, mechanical properties, and corrosion resistance of Ni-W alloy coatings prepared under current densities of 1–5 A/dm², after undergoing heat treatment at 400 °C, 600 °C, and 900 °C. The grain size of the as-plated Ni-W alloy coating was below 10 nm. After heat treatment at different temperatures, the grain size increased, reaching a maximum value of around 30 nm at 900 °C. Heat treatment crystallized and altered the structure of the coating. Different heat treatment temperatures yielded different precipitates, including Ni4W, Ni6W6C, and WC. The highest coating hardness (820–940 Hv) was achieved at 400 °C, while the best corrosion resistance was achieved at 600 °C. The precipitation hardening phase can be obtained by proper heat treatment temperature, yielding the desired properties of the composite coating.

Tensile Strength Enhancement Via Heat Treatment In Directly Recycled Aluminium Alloy (AA6065)

Products made through solid-state recycling of aluminum chips in a hot extrusion process were regulated by temperature-related factors by utilizing a preheating temperature of 350 °C, 400 °C, and 450 °C for one hour, two hours, and three hours of preheating time, respectively. Design of Experiments (DOE) was used, and the findings showed that the preheating temperature is more significant to manage than the preheating duration, and that increasing the temperature led to a high tensile strength. This conclusion was reached as a result of the experiments. The profile that was extruded for three hours at 550 degrees Celsius had reached the ideal condition for achieving the highest possible tensile strength. The heat treatment was carried out with the solution temperature set at 450 degrees Celsius for two hours, and the ageing procedure was carried out at 195 degrees Celsius for three hours. The extruded specimen underwent heat treatment, which resulted in a considerable increase in its tensile strength.

Synthesis of concentric multilayer fullerene nanostructures from mineral coal for applications in supercapacitors

Motivated by the need to find added value to Colombian mineral coal and explore its possible applications in energy storage systems, herein, carbon nano-onions (CNOs) structures were produced from mineral coal through thermal annealing under an inert atmosphere. Three coal samples were extracted from three distinct mines in Colombia, and thermal annealing was conducted on each sample at different times from 1 to 2 h, and temperatures between 1200 and 1600 °C. Through HR-TEM, it was possible to observe the formation of onion-like carbon structures with interlayer distances of 3.86 and 3.50 Å for annealing temperatures of 1600 and 1800 °C, respectively. On the other hand, cyclic voltammetry was carried out to evaluate the potential use of the materials in capacitive systems after undergoing heat treatment showing an increase of up to 5000 % in the specific capacitance of each sample concerning the original carbon. Additionally, the behavior of the charge storage process was analyzed by electrochemical impedance spectroscopy, where faradaic processes obtained the most significant contribution to the enhancement of the specific capacitance.

Miniaturised experimental simulation of open-die forging

This study presents a novel experimental set-up for laboratory-scale simulation of cogging and open-die forging processes during ingot-to-billet conversion of advanced engineering alloys. The experimental set-up is designed to be cost-effective, employing a remotely operated manipulator assembly constructed from readily available “off-the-shelf” components used in conjunction with a conventional uni-axial load-frame - equipment that is available in most materials testing laboratories. Small test-bars of C101 copper alloy were subjected to multi-stroke cogging operations with intermittent rotation at ambient and elevated temperatures (20–600 °C). Prior to forging, the as-received material underwent heat treatments to coarsen the starting grain structure, and to help demonstrate the capability of the apparatus to achieve grain refinement via recrystallisation (dynamic and static) and recovery processes within the deformed material. The resulting microstructural evolution and mechanical property changes of the forged material have been investigated using light microscopy (LM), Vickers hardness (HV) testing, and electron backscatter diffraction (EBSD). The deformed C101 alloy exhibited measurable grain refinement after forging at elevated temperatures, thus demonstrating the effectiveness of the designed miniaturised open-die forging set-up.

Passivation Behavior of Water‐Quenched and Heat‐Treated Ti–6Al–4V in Hank's Solution

Ti–6Al–4V is a prevalent material utilized in various industrial applications, and its microstructure modification commences with quenching, followed by diverse heat treatments. Although many works have concentrated on the mechanical properties of Ti–6Al–4V with tailored microstructures resulting from heat treatments, their corresponding corrosion behavior still lacks attention. In this study, the corrosion behavior of water‐quenched Ti–6Al–4V that undergoes heat treatment between 700 and 850 °C in Hank's solution is investigated. Various electrochemical methods, such as open‐circuit potential tests, potentiodynamic/potentiostatic polarization, electrochemical impedance spectroscopy, and Mott–Schottky tests, are jointly employed. The water‐quenched Ti–6Al–4V displays a quick‐cooling microstructure with a plentiful amount of martensite α/α′ phase. Heat treatment at 700 °C significantly alters the microstructures of the samples. Due to competitive factors, heat treatment at low temperatures results in uneven alloy composition, leading to poor uniformity of the passive film. At this phase, negative effects dominate, and the corrosion resistance of the samples deteriorates. When the heat‐treatment temperature increases to 850 °C, the content of β phase, which possesses better corrosion resistance, increases and becomes dominant. Consequently, the corrosion resistance of the samples improves in Hank's solution.

Optimization of a rapid and sensitive nucleic acid lateral flow biosensor for hepatitis B virus detection.

The utilization of direct amplification of nucleic acid from lysate has attracted interest in the advancement of straightforward and economical point-of-care assays. Consequently, this study primarily focuses on the development of a rapid, precise, and cost-effective lateral flow biosensor for the convenient detection of HBV nucleic acid at the point-of-care. Furthermore, the study evaluates the effectiveness of the direct amplification method in comparison to purified nucleic acid samples within the context of LAMP-LF biosensing approaches. The experiments conducted in this study utilized clinical serum samples that were confirmed as HBV-positive through real-time PCR assays. Sample preparation involved employing spin column nucleic acid purification and serum heat treatment. To amplify a 250bp fragment of the HBV polymerase gene, three pairs of specific LAMP primers were utilized, which were biotin-labeled and FITC-labeled for detection purposes. Various incubation temperatures (ranging from 64 to 68°C) and durations (30min, 45min, and 1h) were investigated to determine the optimal conditions for the LAMP assay. The results were subsequently assessed through fluorometric analysis, white turbidity measurements, and lateral flow assay. Milenia HybriDetect1 strips, designed for immediate use, were employed to visualize the LAMP amplicons. Furthermore, the performance of the lateral flow biosensor was evaluated using 10-fold serial dilutions of a secondary standard containing a viral load of 108 IU/ml. The optimization of the LAMP reaction was achieved at a temperature of 67°C, resulting in significant turbidity after a 30-minute incubation period. When the spin column purification method was employed, varying test bands were observed for templates ranging from 108 IU/ml to 101 IU/ml viral load. However, when serum samples underwent heat treatment and the resulting supernatant was directly used for LAMP, the lateral flow assay was capable of detecting a minimum viral load of 103 IU/ml. In resource-limited settings, the LAMP-LF assay presents a promising solution for HBV testing. However, it is important to note that direct amplification without DNA purification may diminish the performance of the approach.

Experimental study on evaluation of porosity, thermal conductivity, UCS, and elastic modulus of granite after thermal and chemical treatments by using P-wave velocity

Hot dry rocks (HDRs) are subjected to thermal and chemical stimulation caused by water cooling and chemical actions during reservoir reconstruction. The damage caused by stimulation will change the physical and mechanical characteristics of HDRs, which brings potential risks to the operating life and safety of artificial geothermal systems. The material properties of granite specimens treated by heating and long-term static chemical immersion are studied by ultrasonic tests (UT), nuclear magnetic resonance (NMR), thermal conductivity tests, and uniaxial compression tests. Five temperature levels (from 25 to 600 °C) and four chemical immersion conditions (heat treatment only, distilled water immersion, acid stimulation, and alkali stimulation) are considered. The findings demonstrate that porosity rises with the heat treatment temperature, whereas P-wave velocity, thermal conductivity, uniaxial compressive strength (UCS), and elastic modulus fall. Acid stimulation can improve the porosity of heat-treated granite while decreasing P-wave velocity and thermal conductivity. Alkali stimulation easily forms precipitates or colloidal materials to fill the microcracks and micropores inside the heat-treated granite, resulting in reduced porosity and increased P-wave velocity and thermal conductivity. The mechanical properties of the granite that has undergone heat treatment will be further weakened by acid or alkali stimulation. Regression analysis shows an excellent nonlinear logarithmic relation between P-wave velocity and other measured properties. In addition, the damage characteristics and micro-mechanism of the treated granite are discussed by mineral composition analysis and scanning electron microscope (SEM) observation.

Hierarchically porous bioceramics based on geopolymer-hydroxyapatite composite as a novel biomaterial: Structure, mechanical properties and biocompatibility evaluation

In this study, open-cell porous bioceramics based on geopolymers were synthesized by the replica technique. The composition consisted of a mixture of metakaolin (MK) and hydroxyapatite (HA) that combined are suitable for application in bone tissue engineering. Metakaolin is a cheap natural aluminosilicate known for its mechanical properties, while hydroxyapatite stands out for its biocompatibility due to the chemical structure similar to the bone matrix. After undergoing heat treatment (HT), the geopolymer-hydroxyapatite (GMK-HA) synthesized materials, referred to as GMK-HA-HT, presented pores in the range from 1 to 5 mm. In the compressive strength tests, they exhibited values between 1.18 and 2.9 MPa. These ranges of values signify a proper balance between mechanical strength and porosity. X-ray diffraction analysis showed phosphate and/or calcium crystalline phases in all heat-treated samples, indicating HA's successful incorporation in the geopolymer structure. In vitro tests using human adipose-derived mesenchymal stem cells (ADSCs) were conducted to evaluate the biocompatibility of the synthesized materials. The extracts obtained from the GMK-HA-HT were found to be non-cytotoxic. ADSCs in contact with extracts have no morphological changes and when cultured on the GMK-HA-HT surface, the cells interacted with the scaffold and formed a monolayer. Here, for the first time, we provide insights into this new class of materials as a promising biomaterial candidate which could be associated with ADSCs to promote bone healing.

Novel 3D-Printed Biocarriers from Aluminosilicate Materials

The addition of biocarriers can improve biological processes in bioreactors, since their surface allows for the immobilization, attachment, protection, and growth of microorganisms. In addition, the development of a biofilm layer allows for the colonization of microorganisms in the biocarriers. The structure, composition, and roughness of the biocarriers’ surface are crucial factors that affect the development of the biofilm. In the current work, the aluminosilicate zeolites 13X and ZSM-5 were examined as the main building components of the biocarrier scaffolds, using bentonite, montmorillonite, and halloysite nanotubes as inorganic binders in various combinations. We utilized 3D printing to form pastes into monoliths that underwent heat treatment. The 3D-printed biocarriers were subjected to a mechanical analysis, including density, compression, and nanoindentation tests. Furthermore, the 3D-printed biocarriers were morphologically and structurally characterized using nitrogen adsorption at 77 K (LN2), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The stress–strain response of the materials was obtained through nanoindentation tests combined with the finite element analysis (FEA). These tests were also utilized to simulate the lattice geometries under compression loading conditions to investigate their deformation and stress distribution in relation to experimental compression testing. The results indicated that the 3D-printed biocarrier of 13X/halloysite nanotubes was endowed with a high specific surface area of 711 m2/g and extended mesoporous structure. Due to these assets, its bulk density of 1.67 g/cm3 was one of the lowest observed amongst the biocarriers derived from the various combinations of materials. The biocarriers based on the 13X zeolite exhibited the highest mechanical stability and appropriate morphological features. The 13X/halloysite nanotubes scaffold exhibited a hardness value of 45.64 MPa, which is moderate compared to the rest, while it presented the highest value of modulus of elasticity. In conclusion, aluminosilicate zeolites and their combinations with clays and inorganic nanotubes provide 3D-printed biocarriers with various textural and structural properties, which can be utilized to improve biological processes, while the most favorable characteristics are observed when utilizing the combination of 13X/halloysite nanotubes.

Effects of Substituting Soybean Meal by Unprocessed and Processed Peanut Cake Meal on the Growth, Body Composition and Survival of Tilapia (Oreochromis niloticus)

An 8-week feeding trial was conducted to investigate the effects of replacing soybean meal by unprocessed and processed peanut cake meal on the growth, body composition and survival of Nile tilapia fry. Five types of feed were produced: diet 1 containing unprocessed peanut meal (natural NPM), diet 2 toasted peanut meal (toasted TPM), diet 3 fermented peanut meal (fermented FPM), diet 4 steamed peanut meal (steamed SPM) and diet 5 containing soybean meal (SBM). For the diet containing FPM, the fermentation of the mill mixed with yeast lasted 7 days anaerobically. The diet containing SPM was formulated with a steam-treated cake on a couscous steamer held on a kettle. The diet made with TPM underwent heat treatment on a stove. The remaining part of the cake NPM did not undergo any transformation. The experiment was conducted in an open system at the University of Cheikh Anta Diop and lasted nearly for two months. The fish were first subjected to acclimatisation phase prior to the initiation of the trial. The five treatment diets were triplicated and the stocking density was 15 fish per tank with a total of 225 fry with an initial average weight of 0.13 g. The fish were raised in plastic tanks of 50L each and fed three times a day (9 a.m, 1p.m and 5 p.m) at a feeding rate of 8% and 3% of their body weight during the 1st, 2nd to 3rd and 4th 2 weeks respectively. The temperature and dissolved oxygen were monitored in the morning and evening and the culture units were cleaned, siphoned and refilled with water at two third of their capacity prior to the feeding. The results of this study indicated that dietary NPM and TPM could replace SBM without a negative impact on the growth of tilapia. The FCR of the fish fed the diet containing NPM, SPM, TPM are not significantly different with FCR of those fed SBM. There were effects on the body composition of the fish fed diets containing the substitution of soybean meal with processed peanunut cake. The survival rate varied from 93 to 100%. The results of the analysis of the aflatoxin level in the four types of feed containing peanut meal showed that the heat treatment had no effect on the aflatoxin content. The substitution of soybean meal with natural and toasted peanut cake has no adverse effect on growth and feed efficiency of Nile tilapia fry. The authors suggested to use natural or toasted peanut cake for better growth.

3D hierarchical porous structures printed from a silica-nickel composite paste

Material extrusion of paste as one of the 3D printing techniques is commonly used in additive manufacturing industry. It allows to efficiently obtain structures of complex geometry at a relatively low cost. Ceramics are among the materials eagerly printed with this technique, especially as a support material. Hence, the combination of silica as base material and nickel as catalyst seems to be a highly promising system in processes such as CO2 methanation or hydrogenation processes.The key aspects that should be taken into consideration when designing a new material are the proper material composition, its microstructure, as well as the final properties. From the point of view of the above-mentioned applications, material should have high open porosity. Appropriate micro- and macroporosity enable the optimal flow of liquid and gaseous reagents through the material, ensuring high efficiency of the processes carried out. It is also crucial to select the appropriate catalytic material, hence the use of nickel as a catalytically active metal was proposed for the research.This article demonstrates the development, preparation and characterization of silica-nickel porous structures obtained via material extrusion. The nanosilica-Ni paste with 75 wt% of Ni powder particles was prepared with stirring and degassing for homogenous consistency. 3D printed scaffolds have undergone heat treatment to remove the organic binders and partially sintered to achieve a relevant mechanical strength. The analysis of the paste was performed using the detailed thermal analysis, XRD analysis and Raman spectroscopy for a determination of the optimal thermal processing conditions. In addition, the characterization of the final materials was carried out to confirm the effectiveness of the procedures developed. Application of the reductive atmosphere (mixture of N2+H2) during heat treatment prevented nickel particles from oxidation, as well as strongly eliminated the microstructure defects such as cracking and material shrinkage. The results demonstrate the perspective application of material extrusion as a printing technique of highly porous materials with well-preserved pre-designed 3D geometry.

Microstructural characterization and mechanical properties of additively manufactured 21-6-9 stainless steel for aerospace applications

The alloy 21-6-9 is a nitrogen-strengthened austenitic stainless steel often used in aerospace applications due to its high strength, good fabrication properties, and toughness at cryogenic temperatures. However, minimal research has been conducted on alloy 21-6-9 using the additive manufacturing process laser powder-bed fusion (L-PBF). The L-PBF technique has been seen as a key to reducing production time and avoiding costly machining. Therefore, there is an interest in investigating L-PBF-processed 21-6-9 to determine the effects of L-PBF on properties at elevated and cryogenic temperatures. In this study, prior to tensile testing the alloy 21-6-9 underwent heat treatments that simulated aerospace applications and the alloy was analyzed and characterized to evaluate phase stability. The effects of elevated and cryogenic temperatures (77 K) on the tensile behavior and microstructure were investigated using X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). The tensile tests showed that the yield strength and ultimate tensile strength improved, while ductility varied depending on the conditions and test environment. The ultimate tensile strength was approximately 80% higher at 77 K than at room temperature, although the elongation decreased by around 90%, possibly due to the formation of strain-induced martensite.

High internal phase emulsions stabilized solely by alkali-extracted bamboo leaf polysaccharide conjugates

Bamboo leaf polysaccharides have a variety of biological activities, such as antioxidation and immunomodulation, but their emulsifying properties have rarely been involved. In this study, polysaccharide conjugates were extracted from bamboo leaf residue under alkaline conditions, referred to as BLPC- A. BLPC-A aqueous solution and medium-chain triglycerides (MCT) were used as the raw materials to prepare oil-in-water (O/W) high internal phase emulsions (HIPEs). As a single emulsifier, BLPC-A could stabilize 80% (w/w) MCT. With the increase in the BLPC-A concentration (1.00–2.50%, w/w), the average particle size (APS) (d3,2) of the HIPEs gradually decreased, while the viscoelasticity of the HIPEs gradually increased. Furthermore, all HIPEs had good stability during a 30-day storage period at 25 ℃. Among them, after the BLPC-A HIPEs (2.00%, w/w) underwent heat treatment at 40–90 °C, the APS (d3,2) increased from 10.51 µm to 13.01 µm, the tightly packed structure was well maintained, and the HIPEs had good storage stability and enhanced viscoelasticity. When the BLPC-A HIPEs (2.00%, w/w) were exposed to different concentrations of Na+ (0.50–1.00 M) and Ca2+ (0.01–0.05 M), the APS (d3,2) decreased from 8.55 µm to 7.53 µm, and increased from 10.62 µm to 36.54 µm, respectively, while the viscoelasticity was enhanced for each, though HIPEs exposed to Na+ had superior storage stability. These results show that BLPC-A can be used as a natural emulsifier with a good emulsifying effect, while further providing support for the effective utilization of bamboo leaf resources.

Calcination-Enhanced Laser-Induced Damage Threshold of 3D Micro-Optics Made with Laser Multi-Photon Lithography

Laser Direct Writing (LDW), also known as 3D multi-photon laser lithography of resins, is a promising technique for fabricating complex free-form elements, including micro-optical functional components. Regular organic or hybrid (organic–inorganic) resins are often used, with the latter exhibiting better optical characteristics, as well as having the option to be heat-treated into inorganic glass-like structures particularly useful for resilient micro-optics. This work is a continuation of our SZ2080™ calcination development of micro-optics, specifically studying the Laser-Induced Damage Threshold (LIDT). Such sol–gel-derived glass 3D micro-structures, particularly those that undergo heat treatment, have not been well-characterized in this respect. In this pilot study, we investigated the LIDT using the Series-on-One (S-on-1) protocol of functional micro-lenses produced via LDW and subsequently calcinated. Our results demonstrate that the LIDT can be significantly increased, even multiple times, by this approach, thus enhancing the resilience and usefulness of these free-form micro-optics. This work represents the first investigation in terms of LIDT into the impact of calcination on LDW-produced, sol–gel-derived glass micro-structures and provides important insights for the development of robust micro-optical devices.

Structure formation and properties of sheet structural steels in the modes of ordinary and combined heat treatment with exposure in the intercritical temperature range

The features of the structure, the nature of the distribution of alloying elements and impurities between the structural components of sheet low-alloy steels that have undergone heat treatment with exposure in the intercritical temperature interval (ICTI), the structure formation and mechanical properties of these steels after the combined regimes of heat treatment with exposure in the ICIT were investigated. The analysis of the distribution of elements among the structural components of the studied low-alloy steels allowed us to establish that during heat treatment with direct exposure in the ICTI, such elements as manganese, chromium, aluminum, vanadium, sulfur, and phosphorus are concentrated mainly in the strengthening martensitic-bainite phase, while nickel, silicon and titanium are evenly distributed between the strengthening phase and ferrite. The conducted research on the example of sheet low-alloy steel 14G2 shows that the effects of grinding of ferritic grain, peаrlitic and martensitіс (bainite) components during combined processing with exposure in ICTI can be caused by implementation at low (450-550ºС) temperatures of isothermal decomposition the mechanism of multiple nucleation of ferrite microcrystals. It was established that the combined regimes with exposure in ICTI allow, without the application of hardening and tempering operations, to achieve in sheet low-alloy steel 14G2 mechanical properties at the level of strength class 390 according to DSTU 8541:2015 with yield strength values of 422-425 МPа and with high plasticity and impact viscosity Therefore, the use of these modes in a modified form can be recommended for the creation of end-to-end energy-saving technologies of heat treatment with exposure in the ICTI of low-alloyed steel sheet in the flow of thick-sheet mills equipped with normalization units. Keywords: structure formation, intercritical temperature interval, isothermal decomposition, martensitic-bainite phase, combined regime.

Camel livestock in the Algerian Sahara under the context of climate change: Milk properties and livestock production practices

Camel livestock is an ancestral activity in Algeria; however, climate change has forced camel herders to modify their breeding practices to make them more sustainable. This study summarized livestock production practices, milk qualities, and the potential of camel livestock to preserve production ability under global warming. To collect data related to livestock farming practices, 10 camel herders were interviewed using a formal questionnaire. Then, 15 milk samples (9 samples of raw milk and 6 samples that had undergone heat treatment) were collected in the region of Oued Souf in southeastern Algeria to carry out the physicochemical and bacteriological analysis. From 1990 to 2021, results showed severe drought accompanied by a significant increase in the annual average maximum temperature with a temporal slope of 0.04 °C year−1 and a significant decline in annual precipitation with a temporal slope of −0.07 mm year−1. A socio-demographic survey revealed a low educational level for camel herders. They owned small herd of camels (6.84 ± 8.66 camels) in the transhumant and extensive system or > 150 heads in the nomadic and extensive system. The average daily milk production in the nomadic system was very low (<3 L/day); it was less important compared to that in the transhumant system (4–5 L/day), with an acceptable physicochemical quality but poor bacteriological quality. Given the susceptibility of the research area, we recorded that camel livestock and travel mobility were used as adaptation strategies to the effects of climate change. On the one hand, camel breed conservation programs can enhance biodiversity and a sustainable ecosystem. On the other side, a genetic improvement program that might boost productivity and profitability might be advantageous. Smallholders may benefit from this by receiving a fair and secure income and good working conditions, which could contribute significantly to social equity and local economies.

Justification of the design and regime parameters of a mobile grain dryer

Relevance. Improving the efficiency of grain drying is possible by increasing the intensity of moisture evaporation from the processed material and reducing energy costs. In this regard, the task was set to study a small-sized mobile installation for drying grain, which would meet the requirements of small-scale agricultural production, as well as to substantiate drying modes.Methods. As a result of the analysis of a priori information, as well as taking into account the relevant requirements, the factors that most affect the grain drying process were identified. At the proposed installation, laboratory studies were carried out in the drying mode of wheat of the Moskovskaya 39 variety. During the research, measurements of the corresponding parameters were carried out. A systematic approach was used to generalize the theoretical and experimental results of the study.Results. An installation for drying grain in conditions of small-scale farms is proposed. During the drying process on this installation, the following is ensured: a uniform supply of heated air to the entire area of the grain layer undergoing heat treatment; continuous removal of moisture formed on the surface of the grain. In this paper, expressions are proposed for determining the power required for drying grain and the specific power consumption with a decrease in grain moisture. The studies carried out made it possible to identify the dependences of the specific power consumption and moisture removal on the temperature and speed of the drying agent, drying exposure. The dependences obtained made it possible to establish that this installation, at the optimum temperature of the drying agent of 60 ± 2.5 °C, is adjustable within 8 ± 2.5 W· h/kg·% specific energy consumption and provides 5% moisture removal. The developed installation has operational parameters acceptable for small farms.

THEINFLUENCE OF MODIFICATION WITH YTTRIUM ON THE STRUCTURE AND PROPERTIES OF CASTINGS OBTAINED FROM THE ЖС6У-ВІ ALLOY RETURN

Purpose. To study the effect of modification of nickel-yttrium ligature with additives on the structure and physical and mechanical properties of ЖС6У-ВІ alloy, smelted using its own technological return in the charge.&#x0D; Research methods. On the УППФ-3М installation with the base crucible, experimental melting of standart technological return of the ЖС6У-ВІ alloy was carried out using high-temperature melt processing.&#x0D; Experimental samples for mechanical tests and determination of stress-rupture strength were cast from the obtained ingots, cut into measured batch blanks and cleaned in a shot blasting drum, using the method of equiaxial crystallization in ceramic molds.&#x0D; When pouring one ceramic mold, the metal melt at a temperature of 1540 °C was modified with a nickel-yttrium ligature of the ІтН1 brand (grain size 2...5 mm) in the amount of 0.136 % of the mass of the charge in a crucible with a holding time of 1 min 15 s ... 1 min. The second block was poured without modification.&#x0D; Cooling of the poured blocks was carried out at the melting site at normal ambient temperature.&#x0D; The samples underwent heat treatment according to ОСТ 1 90126-85: heating to a temperature of 1210 ± 10 °C, holding for 4 hours, cooling in air.&#x0D; The balance of the chemical composition of the experimental alloys was evaluated by the computational and analytical method.&#x0D; The chemical composition of the alloy of experimental variants was determined. The microstructure and mechanical properties at room temperature were studied. Stress-rupture strength tests were performed at 975 °C under a load of 230 MPa.&#x0D; Results. Experimental melting of the charge was carried out, which consisted exclusively of our own technological return of the ЖС6У-ВІ alloy with the use of high-temperature processing of the melt and modification with a nickel-yttrium ligature.&#x0D; The chemical composition, microstructure of the experimental alloy, its mechanical properties at room temperature, and heat resistance indicators were studied.&#x0D; A method of determining the degree of balance of the chemical composition of modern superalloys based on the total content of groups of alloying elements is proposed.&#x0D; Scientific novelty. Calculations carried out in accordance with the proposed method of determining the degree of balance of the chemical composition of the alloy show that for the experimental variants, phase separations may form along the grain boundaries. Studies of the microstructure confirmed the separation of the γ-γ' eutectic phase in the form of a “white” border along the thickened grain boundaries in the metal of the ЖС6У-ВІ alloy sample.&#x0D; According to the calculations of the metal alloying system balance for experimental melts, not only the thickening of the grain boundaries and the separation of the γ-γ' eutectic phase, but also a decrease in mechanical properties and stress-rupture strength can be observed.&#x0D; The application of modification with nickel-yttrium ligature in the amount of 0.136 % in the remelting process with the use of high-temperature processing of the ЖС6У-ВІ alloy return melt allows to ensure the formation of grain boundaries without visible discharges (pollution).&#x0D; It was established that in the metal of the experimental melting with the application of modification with nickel-yttrium ligature, carbides have globular and lamellar morphology. There is no separation of the γ-γ' eutectic phase.&#x0D; The mechanical properties and stress-rupture strength of the metal of the experimental melts with the use of high-temperature processing of the melt of the conditioned return of the ЖС6У-ВІ alloy, both with and without modification by nickel-yttrium ligature, meet the requirements of OST 1 90126-85, but at the same time, they are lower than the properties of the alloy cast with charge refreshment.&#x0D; Practical value. A computational and analytical method of determining the degree of balance of the chemical composition of modern heat-resistant alloys based on the total content of certain groups of alloying elements is proposed.&#x0D; It was established that the modification of nickel-yttrium ligature with additives significantly improves the microstructure of castings obtained from the technological return of the ЖС6У-ВІ alloy and creates conditions for a general improvement in the quality of the material of the responsible castings.&#x0D; The conducted studies show that the use of 0.136 % nickel-yttrium ligature allows to clean grain boundaries, change the morphology of non-metallic inclusions and counteract the segregation of eutectic inclusions in nickel-based superalloys alloys.

Two-step combustion synthesis of single-phase mesoporous ScFeO3 with bixbyite structure and magnetically soft behavior

In this paper, we consider the possibility of obtaining cubic bixbyite-type scandium ferrite in the form of phase-pure nanopowders. The samples were obtained by solution combustion method with either lack or excess of fuel and represented an X-ray amorphous phase according to the X-ray diffraction (XRD) results. To obtain cubic scandium ferrite, the samples were subjected to heat treatment at 700 °C, determined using DTA/TGA. The XRD data analysis confirmed the formation of cubic scandium ferrite with an average crystallite size of ∼20 nm for the sample obtained with a lack of fuel and 13 nm with an excess of fuel. According to the low-temperature nitrogen adsorption-desorption technique, the specific surface of the mesoporous samples decreased after annealing from 39.7 m2/g to 20.5 m2/g for the sample obtained with a lack of fuel and from 82.7 m2/g to 34 m2/g for the sample obtained with excess fuel. Scanning electronic microscopy (SEM) results demonstrated the foam-like morphology of nanopowders and no significant changes in their microstructure after heat treatment. The magnetic properties of powders that have undergone heat treatment have been studied. Narrow M-H hysteresis loops and low values of the coercive force indicate ferromagnetic behavior of the synthesized nanoparticles, which is supported by low values of the coercive force (Hc = 345 Oe and 769 Oe), remanent magnetization (Mr = 0.65 emu/g and 0.26 emu /g) and saturation magnetization (Ms = 1.69 emu/g and 0.26 emu/g) for lack and excess of fuel, respectively. The obtained materials are classified as magnetically soft and can potentially be used in the creation of transformers, magnetic screens, magnetic memory systems, radio engineering, and computer technology.