Inert Gas Research Articles

On the product phases and the reaction kinetics of carbothermic reduction of UO2+C at relatively low temperatures

The synthesis of UC using carbothermic reduction of UO2 and C mixtures has been well studied at high temperatures. However, the product phase behavior of carbothermic reduction at low temperatures (≤1773 K) is not well studied. Such a study is important as low temperatures permit single phase UC synthesis without forming secondary higher carbides, and it further supports the knowledge base of the process that needs to be used for transuranic elements such as plutonium that have high vapor pressures at elevated temperatures. Therefore, a low temperature carbothermic reduction of two different C/UO2 molar ratios under inert and reducing environments have been studied here. Two different sample holding crucibles, alumina (Al2O3) and graphite, were also used here to differentiate the hypostoichiometric (UC1-a) and oxygen dissolved (UC1-xOx) uranium monocarbide phases adding more details on the two systems. Also, the reaction kinetics involved in the formation of UC via the carbothermic reduction of UO2+C using product phases instead of evolved gases such as carbon monoxide is reported here. Under inert atmospheres but with significant oxygen partial pressures, the low temperature carbothermic reduction of UO2+C produced up to 90 wt.% UC1-xOx type oxycarbides as was confirmed by Xray powder diffraction. Reducing Ar-4%H2 environments at these temperatures were not successful in synthesizing UC as it reduces the amount of C required for the carbothermic reduction, leaving UC phase at a non-equilibrium state. Inert atmospheres with low or negligible oxygen partial pressures on the other hand produced near stoichiometric UC at high phase purity, especially at 1673 – 1773 K temperature range. An activation energy of 377±75 kJmol-1 was also calculated using product phase concentrations of the carbothermic reduction of UO2+C under these inert Ar(g) atmospheres.

Design and testing of an (inert) gas cell for in situ polarization modulation infrared reflection absorption spectroscopic (PM-IRRAS) measurements under specific atmospheres.

Infrared reflection absorption spectroscopy (IRRAS) is a powerful surface-sensitive analytical technique to characterize the adsorbed molecules on metal surfaces down to (sub)monolayer coverage. In this paper, a new (inert) gas cell is presented that expands the scope of the commercially available Bruker PMA50 module. The cell is designed as a sample holder to measure thin films of molecules adsorbed on a metal substrate under a specific gaseous atmosphere. The dimensions of the cell are chosen in such a way that it can be transferred into a glovebox via the standard entrance port (Ø150mm), allowing the investigation of air-sensitive molecules under an inert-gas atmosphere. The cell has two hose connections through which the gas atmosphere can be varied as desired. This also allows for studying the reactivity of the adsorbed structures toward the surrounding gas in situ and in a (potentially) time-dependent fashion. Furthermore, the metal substrate can be irradiated via an exposure window to investigate the influence of light on the adsorbed molecules and/or their reactivity. Using the polarization-modulation (PM-) IRRAS technique along with the described gas cell, an air-sensitive molybdenum(0) tricarbonyl complex adsorbed on an Au(111) surface is investigated. This complex reacts with molecular oxygen to the molybdenum(VI) trioxo analog, and this conversion is accelerated by irradiation with light of 365 and 440nm.

Electrical properties and redox stability of series novel high-entropy Bi2VO5.5-based oxides

Exceptional high ionic conductivities have been well documented in the Bi2VO5.5-based materials. However, the poor phase and redox stabilities under a reducing atmosphere hindered their wide applications. Herein, with the aim to improve the phase and redox stabilities under a reducing atmosphere, a high-entropy strategy of multiple-metal-doping was applied to prepare series Bi2V1–4x(GaSiTaZr)xO5.5-δ (0 ≤ x ≤ 0.1) materials by a traditional solid state reaction method. The results revealed that multiple-metal-doping could stabilize the tetragonal phase of Bi2VO5.5 to room temperature and shown good phase and structural stabilities under inert or high oxygen partial pressure atmospheres, as well as pure oxide ion conduction which was about two orders of magnitude higher than that of the parent material, e.g. ∼2.0×10−2 S/cm at 400 ºC for the x = 0.05 sample while ∼1.5×10−4 S/cm for the x = 0 sample. Although the Bi2V1–4x(CuNiNbTi)xO5.5-δ materials would still be readily reduced under a reducing environment and introduce strong electronic conduction, the phase stability was apparently improved. Thus, improving the redox stability and suppressing the electronic conduction of the stabilized Bi2VO5.5-based materials under a reducing atmosphere is still the direction we should strive for.

Direct reduction of CO2 to carbon material on liquid cathode in molten salts

This study presents a novel method for the direct reduction of CO2 to produce carbon materials on a liquid cathode in high-temperature molten salts. CO2 gases were introduced into a Sn-Li liquid alloy, and they were subsequently reduced to solid carbons by the Li in the alloy. Unreacted CO2 gases were absorbed as carbonate ions (CO32−) in molten salts containing oxide ions (O2−). Subsequently, these carbonate ions were electrochemically reduced to solid carbons on the liquid cathode surface. Consequently, the current density was five times higher than that achieved using the conventional method without bubbling CO2 into the liquid cathode. The enhanced current density can be attributed to the combined thermochemical reduction of CO2 by Li and the electrochemical reduction of CO32−. This combination was realized for the first time at a relatively positive potential range, where pure Li or Ca cannot be deposited, leading to the carbon yield of over 90 % relative to CO2 feed reached. The resulting carbons contained a trace amount of Sn, which could be removed by washing after milling. These results show the potential for efficient and sustainable carbon capture and conversion technologies using liquid cathodes in high-temperature molten salts for CO2 reduction.

Physical, optical properties and antibacterial activity of silver nanoparticles: Nanoclusters to nanoparticles formation on glass substrate by in-situ annealing

Silver nanoparticles (AgNPs) formed on in-situ annealed microscopic glass substrates from silver nanoclusters (AgNCs) generated by DC magnetron sputtering with inert gas condensation (IGC) technique. The substrate’s annealing temperature was below and above the glass transition temperature of 500 ºC and 600 ºC. The influence of annealing temperature on the surface morphology was studied using atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) were employed to investigate the surface composition, chemical states, and electronic states of the AgNPs on the glass substrates. On the in-situ annealed glass substrate at 500 ºC, the produced AgNPs revealed accumulation and aggregation. For in-situ annealed at 600 ºC, a homogeneous distribution of AgNPs on the glass substrate was witnessed. The refractive index test revealed that AgNPs deposition at 600 ºC achieved higher sensitivity with 27nm/RIU (Refractive index unit). The antibacterial activity of AgNPs was also investigated using Escherichia coli and Bacillus cereus. In contrast, better antibacterial activity was obtained with in-situ annealing at 500 ºC, where 4-fold reductions compared with the control sample. Pre-determined properties can be precisely executed to achieve the desired performance as the so-called application-oriented engineered surface in the UHV system is established. This research highlighted the differences between two different annealing temperatures' effect on the base substrate material, which subsequently impacts the structure of AgNPs and their applications. Furthermore, the outcome of this work could contribute to the multifunctional surface for detecting heavy metals, various organic pollutants, and disinfection of water and food-borne pathogenic diseases.

From biomass to power: High-performance reactor design for coking-resistant operation

Biomass gasification coupled with solid oxide fuel cell (SOFC) technology utilizes the gas generated from biomass gasification directly as fuel for SOFC, thereby realizing power generation from solid waste. This technology combines the carbon–neutral feature of biomass with the high efficiency and low emissions of SOFC, making it a promising route for clean energy generation. However, biomass gasification syngas possesses a complex composition, including a high concentration of inert gases, which imposes higher requirements on SOFC. This study developed a multi-channel, hierarchical structural design based on the commercial NiO-yttria-stabilized zirconia (YSZ) material system, realizing high-performance power generation using biomass gasification syngas. The results showed that the combination of a unique structural design and an enhanced interface electrochemical reaction effectively mitigates the influence from inert composition dilution. When operating in gasification syngas with nearly 60 % inert components, the power density can reach 2.07 W·cm−2 (750 °C). In addition, due to the spatial separation of the inert support region and the electrochemically active region, the effect of controlling the position of carbon deposits was achieved, demonstrating 100 h stable operation with dry biomass gasification syngas. Hence, the combination of micro-tubular SOFC with distinctive structural regulation and biomass gasification exhibits promising prospects for further development.

Increase of bridge length by ingenious grafting of ester chains, imparting epoxy resins superb thermal, smoke suppression, gas-phase flame retardancy, and mechanical properties

While bifunctional synergistic flame retardants have demonstrated efficacy in enhancing the fire safety of epoxy resins (EPs), the grafting of specific functional monomers into flame retardant molecules, elucidating their mechanisms of action through comparative analysis, and concurrently achieving a delicate balance among flame retardancy, heat resistance, and mechanical toughness remains a significant challenge. Herein, this research present an innovative strategy to derive a novel sulfur-based bifunctional flame retardant, DSTA, based on the structure of the original flame retardant, DST, by grafting the ester chains to increase the bridge length of the molecular structure. As expected, the addition of flexible ester chains enabled DSTA to have a very high initial decomposition temperature and the heat-resistance index. DSTA can be used in low dosage compared to DST, enabling EP to achieve UL-94 V-0 rating. Combustion behavior showed that DSTA had the best ability to heat and smoke suppression for EP, and had faster response speed and higher fire growth index. Notably, pyrolysis volatiles tested on DSTA revealed that the ester chains can pyrolysis to release large amounts of CO2, which occurs in the early stages of pyrolysis and works together with other N-containing inert gases and P-containing radicals in the gas-phase to efficiently extinguish flames. Meanwhile, DSTA improves all mechanical properties of EP, which was attributed to the presence of ester chains. In summary, this work presents a new strategy for examining the impact of specific functional groups on the flame retardant mechanisms of EP.

Electrochemical synthesized copper mesh catalysts for catalytic combustion: A comprehensive study of Mn doping and atmospheric conditions during calcination

Metal-based monolithic catalysts offer significant advantages in heterogeneous catalysis attributed to their exceptional thermal conductivity and mechanical strength. However, controlling the loading of active components on metallic substrates remains a major challenge. Here, we synthesized a Mn-doped Cu mesh catalyst using a facile electrochemical method, allowing the active components to grow directly on Cu mesh without extra pretreatments or binding agents. The synthesized catalyst exhibits approximately a 30 % increase in carbon monoxide oxidation activity at 100°C and a 60 % increase in toluene oxidation activity at 240°C compared to the Mn-free Cu mesh catalyst. We found that calcination in inert gases enhances interactions between Cu and Mn species, leading to more oxygen vacancies and adsorption sites for reactants. This investigation paves the way for fabricating multi-metal monolithic catalysts on metallic substrates.

Tribological Performance Enhancement of AISI 1050 Steel through FeNiCrCoMo High-Entropy Alloy TIG Weld Cladding

The tribological behavior of tungsten inert gas (TIG) welded high entropy alloy (HEA) FeNiCrCoMo cladding deposited on AISI 1050 steel substrate was studied. The response surface methodology (RSM) optimized the TIG welding parameters. The SEM images revealed no signs of intermetallic compounds in the cladding, and the XRD analysis showed that the FeNiCrCoMo greatest peak corresponds to the BCC+FCC mixed phase. The microhardness and sliding wear resistance of the cladding were superior compared to the steel substrate owing to the solid solution strengthening and the presence of mixed phase. The worn surfaces of HEA claddings showed the presence of wear debris, grooves and micro-cutting from sliding wear as revealed by the SEM and 3-D profilometry images.

Forming control and the relationship between microstructure and mechanical property in TIG-assisted friction stir welded joint of Ti-6Al-3Nb-2Zr-1Mo titanium alloy

In this paper, T-joints of Ti-6Al-3Nb-2Zr-1Mo titanium alloy were joined with friction stir welding, and microstructure evolution and forming mechanism were studied. The effect of using tungsten inert gas welding to heat additionally the FSW was investigated. Results show a strong effection microstructure of stir zone (SZ) due to the temperature gradient and fast cooling rate. The top and middle sections of SZ have a basketweave microstructure, while there is duplex microstructure at the bottom. When welding at 750 rpm-50 mm/min, the maximum tensile strength of the joint is similar to that of the base metal (BM). As the heat input increases, grain coarsening occurs, which reduces the joint tensile strength and the ability to plastically deform. The fracture mode changes from mixed fracture to ductile one. When TIG-assisted heat source is 20 mm in front of the tool and the power input is in 600 W, the temperature field produced is relatively uniform, which has a positive effect on the weld.

Thiol‐Ene Coupling Reaction for Functionalization of Non‐Activated Alkenes: An Experimental Study on the Chemistry of the Methyl Oleate Amination

AbstractThis work investigates the functionalization of molecules with non‐activated internal double bonds via thiol‐ene coupling (TEC) reaction. A comprehensive study of the reaction between cysteamine hydrochloride (CAHC) and methyl oleate (MO) was carried out. A series of reactions were conducted under different operating conditions in order to assess their effect on conversion and selectivity. Different conditions were considered like the type of atmospheres and solvents, a portionwise addition of CAHC, reagents concentrations, and excess of CAHC. Maximum conversion and selectivity were reached under inert atmosphere, diluted conditions, ethanol as solvent, and the addition of CAHC at the beginning of the reaction with a molar ratio of CAHC/MO of 3/1. This provides an approach for analyzing more complex reaction systems.

Challenges and Perspectives of Georgian Kvevri Wine Production

This research examined the quality of Georgian Amber Kvevri wines produced in the last three years via sensory evaluation and identified common defects in Kvevri amber wines. The Georgian Wine Guild organized 32 tasting sessions, assessing 1,440 amber wines sourced from 149 cellars. Only 30.76% of the wines evaluated were free from faults. High levels of ethyl acetate, acetaldehyde, and volatile acids characterized the majority of faulty wines. Researchers collaborated with 18 local wineries to conduct a field study, revealing that errors in cellar planning, design, and winemaking contributed to defects in Kvevri Amber Wines. The identified mistakes comprised placing kvevries in close proximity, failing to adequately wash and sanitize the cellar, neglecting the use of sulfur dioxide and inert gases, fermenting wines at elevated temperatures, and excessively maturing wines with lees and solid grape components. Based on the obtained results, the study team developed a novel technique that integrates traditional and modern methods for the production of amber wine. The team implemented the traditional liming method for the installation of new wines, produced trial wines utilizing innovative approaches, and created control wines through the conventional method. Trial and control samples were prepared from Georgian endemic grape varieties Rqatsiteli, Kisi, and Khikhvi, which are typically employed in the production of kvevri amber wine. The accredited Wine Laboratory conducted the chemical analyses. The results indicated that the trial wine had three times lower levels of acetaldehyde, ethyl acetate, and volatile acids compared to the control samples. The study emphasizes the significance of reinstating authentic traditional Kvevri winemaking methods alongside contemporary practices. The research indicates that the application of the new technique enables winemakers to improve the sensory attributes of their wines and diminish off-flavors.

Analyzing the Influence of Welding Process Selection on Residual Stresses in Tube-to-Tubesheet Welded Joints

Tube-to-tubesheet joints are used in the fabrication of shell and tube type heat exchangers, steam generators, boilers, condensers, and end shields of pressure tube type nuclear reactors like CANDU (Canada Deuterium Uranium) and PHWR (Pressurized Heavy Water Reactor). The weld joints connecting the tubes to the tubesheets are of prime importance as they have a direct impact on equipment safety. In the fabrication of these critical class-1 nuclear components, full penetration weld joints are used. Typically, these full penetration weld joints are created through multi-pass Tungsten Inert Gas (TIG) welding. However, more recent techniques, such as single-pass Electron Beam Welding (EBW) and Laser Beam Welding (LBW), have also been employed for this purpose. The fabrication time of these pieces of equipment containing full penetration weld joints can be drastically reduced if single-pass welding techniques are used compared to multi-pass welding techniques. However, the residual stresses developed in these joints due to the localized heat input and the substantial constraints of the tubesheet are unknown. Different welding processes, such as TIG welding, EBW, or LBW, can lead to varying levels of residual stresses in these joints, subsequently impacting their longevity. Weld residual stress plays a significant role in the initiation of failure modes of these tube-to-tubesheet welded joints, such as stress corrosion cracking, fatigue, and corrosion fatigue.This paper analyzes the residual stresses developed at the tube-to-tubesheet interface resulting from different welding techniques, such as multi-pass TIG welding and single-pass EBW/LBW. A comprehensive three-dimensional coupled thermo-mechanical finite element analysis is employed for this purpose. The findings reveal a significant difference, with single-pass EBW exhibiting up to 32% lower residual stresses compared to multi-pass TIG welding. Additionally, the Heat Affected Zone (HAZ) in EBW is approximately 50% smaller than in TIG welding, and the equivalent distortion in EBW is reduced by 90% compared to multi-pass TIG welding. In summary, this investigation concludes that single-pass EBW offers distinct advantages for tube-to-tubesheet weld joints, including reduced residual stresses, a smaller HAZ, and lower distortions.

Effect of Submerged Arc Welding (Saw) Parameters on Aisi 1020 Steel

Abstract: This research investigates the Submerged Arc Welding (SAW) process applied to AISI 1020 steel plates (450 mm x 300 mm, 12 mm thickness). A V-groove shape was prepared for welding using Tungsten Inert Gas (TIG) rooting. To achieve optimal results, welding parameters such as current, voltage, and travel speed were optimized. Following this experimentation phase, parameter selection was guided by a comprehensive literature review. Microstructure observations for the welded bead, HeatAffected Zone (HAZ), and base metal were then reviewed in the existing literature, highlighting this study's unique focus on parameter optimization. The findings provide valuable insights for industries relying on welded components, enhancing quality and reliability in AISI 1020 steel welding applications.

Thermal Oxidation Characteristics and Kinetics of Micron Aluminum Powder in Different Ambient Oxygen Concentration Atmospheres

This paper examines the effect of oxygen concentration on the oxidation process and properties of aluminum particles, providing valuable insights for production and storage. Micron-grade aluminum powders were tested at heating rates of 5, 7.5, 10, and 15 K/min under oxygen concentrations of 7, 11, 15, 21, and 30 vol%. Results indicate a two-step mass gain oxidation process, with less pronounced mass gain at lower oxygen concentrations. SEM and XRD characterized the morphological and crystalline changes during oxidation. Lowering oxygen concentration from 30 vol% to 7 vol% increased the onset oxidation temperature by 17.1 °C. Increasing the proportion of inert gas in the atmosphere increases the ignition temperature of aluminum powder. The mathematical modeling approach of AKTS was used to decouple and analyze the thermal effects of simultaneous melting and oxidation, using the Friedman method to show that the apparent activation energy is about 350 kJ/mol in low-oxygen atmospheres (7 vol% and 11 vol%). The kinetics of aluminum oxidation were found to be closely related to the oxygen concentration, and based on the kinetics parameter, it is possible to predict a minimum limiting oxygen concentration.

Thermal engineering and chemical kinetics of wood pellets torrefication

Relevance. The widespread distribution and availability of biomass in the regions of Russian Federation make it possible to consider it as a renewable energy source with a lower negative impact on the environment compared to fossil fuels, since biomass is recognized as a carbon-neutral fuel. The use of biomass as a fuel in the form of pellets is increasing, which provides increased density and heat value. At the same time, pellets as a fuel or as a technological raw material have a significant disadvantage – low hydrophobicity. This problem is solved by torrefaction – low-temperature pyrolysis at a temperature of 200–300°C to produce bio-carbon. The study of the wood pellets torrefaction in order to improve it is an urgent task. Aim. To identify the impact of the parameters of the torrefaction of wood pellets on the thermal characteristics of the product (the highest heat value of bio-coal) and the regime parameters of the process (mass and energy yields), as well as to determine the parameters of the chemical kinetics of low-temperature pyrolysis as the basis for mathematical modeling and development of efficient torrefaction reactors. Object. Torrefied coniferous wood pellets of domestic production (Moscow region). Methods. Experimental study of the low-temperature pyrolysis thermal characteristics; synchronous thermal analysis in an inert atmosphere. Results. It was found that during the torrefaction of wood pellets in an inert atmosphere, a change in the holding time in the range of 30–60 minutes does not significantly affect the higher heat value, mass and energy yield of bio-coal, while an increase in temperature from 250 to 300°C reduces mass and energy yield, and the higher heat value increases by 26%. The dynamics of mass loss and thermal effects when heated to 600°C at a rate of 10 K/min are determined by means of the synchronous thermal analysis. It is established that the chemical kinetics of the process is described by a generalized reaction of the order n=1.507, in the Arrhenius equation the activation energy E=71.25 kJ/mol, the pre-exponential factor A=4772 s–1.

Oligomerization of Fischer-Tropsch Olefins by Radical Initiation Method for Synthesizing Poly Olefin Base Oils

In the present work we have investigated the oligomerization process of Fischer-Tropsch synthesis products – gasoline (C5-C10) and diesel (C11-C18) hydrocarbon fractions with a total olefin content (consisting mainly olefins with a branched isomeric chain) of 79.3 and 31.8 wt.%, respectively. Oligomerization was carried out by radical initiation method using azobisisobutyronitrile, benzoyl peroxide, dicumyl peroxide and methyl ethyl ketone peroxide (Butanox M-50) as initiators. It was established that the yield of the oligomerization process depending on the initiator used decreases in the following order: azobisisobutyronitrile > benzoyl peroxide > dicumyl peroxide > Butanox M-50. It was determined that when the oligomerization is carried out in polar solvents such as acetone and dichloromethane the yield of product increases by ~2.1 and ~1.7 times, respectively, while at the same time adding a non-polar solvent such as tetrachloromethane to the reaction mixture decreases the product yield by ~2.0 times. The optimal technological parameters for carrying out oligomerization process of synthetic gasoline and diesel fractions were determined: where azobisisobutyronitrile, content 0.5 wt.%., is used as an initiator, acetone as solvent, with reaction temperature of 200 °C, and duration of 12 hrs. under inert atmosphere. The product yield from the diesel fraction is 39.5 %, and from the synthetic gasoline fraction – 36.0 %. At the same time, in terms of characteristics, the oligomerization product of the diesel fraction showed properties similar to commercially available Base oil 3cSt (Group III), and the gasoline fraction showed properties on par with the commercially produced PAO-2 (Group IV). Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Study on some Correlations between Hardness with Process Parameters Applying on Welded Joints Made through TIG Welding Process Using High Frequency Pulsed Arc

TIG (Tungsten Inert Gas) welding has more and more application options. To always create new ways of optimization, a more in-depth study of the effects on the components subject to joining is necessary. The paper includes a study on the hardness resulting in the specific areas of the welded joint, using TIG welding with high frequency pulsed arc, applied to join some stainless-steel plates. The relative variation of the hardness was determined and analysed, in correlation with the process parameters. The study is part of the research on obtaining a good energy efficiency in the welding process, based on the requirements imposed on the quality of the joints.

Studies on Tribological Characteristics and Wear Mechanisms of (TiN + TiC) Hybrid Nanocomposite Claddings Deposited on TC4-Grade Titanium Alloy Substrate by the Tungsten Inert Gas Cladding Process

Abstract This investigation explored the viability of tribological properties enhancement with the deposition of TiC + TiN nanoparticulate-reinforced hybrid composite claddings in TC4-grade titanium alloy to meet the ever-increasing functional performance requirements employed under aggressive tribological environments. The composite claddings are processed by using the tungsten inert gas cladding process. The tribological performance of the hybrid composite cladding deposition was evaluated against the claddings with simplex reinforcement compositions such as TC4/TiC and TC4/TiN composite claddings and the substrate alloy. Initially, the formation and microstructural characteristics of the composite cladding depositions are studied based on the scanning electron microscope, X-ray diffraction, and energy dispersive spectroscopic analyses to confirm their successful formation. The average microhardness achieved with the deposition of composite claddings such as TiC/TC4, TiN/TC4, and (TiC + TiN)/TC4 is 936.25 HV0.2, 858.88 HV0.2, and 1116. 72 HV0.2, respectively, while the TC4 substrate alloy is about 332.38 HV0.2. The (TiC + TiN)/TC4 hybrid composite cladding composition has shown significantly increased surface hardness which is about 30% and 18%, respectively, compared with the TiC/TC4 and TiN/TC4 composite cladding compositions while about 235% enhancement compared with the TC4 substrate alloy. Compared with the TC4 substrate alloy, the wear resistance enhancement achieved with the deposition of TiC/TC4 and TiN/TC4 composite claddings is up to 22.62% and 38.92%, respectively, while with the (TiC + TiN)/TC4 hybrid composite claddings is up to 49.87%. Similarly, the average CoF of the TC4 substrate alloy, TiC/TC4, TiN/TC4, and (TiC + TiN)/TC4 composite claddings observed are 0.76, 0.49, 0.58, and 0.44, respectively, which indicates that 36%, 23%, and 43% are the enhancements achieved with the respective composite claddings. The SEM analysis of worn surfaces of the composite claddings reveals typical wear mechanisms such as adhesive, abrasive, oxidation, and delamination that are represented by various regions identified on the generated wear maps. The adhesive and delamination wear regions are relatively wider for the TiN/TC4 composite cladding than the TiC/TC4 composite cladding. The wear mechanism of the composite cladding with multiphase TiC and TiN reinforcement particulate has shown an increased prevalence of abrasive wear as a consequence the abrasive wear region is wider while decreasing the window for adhesive and delamination wear.

Sintering behaviours of different ladle filler sands with high-chromium stainless steel

In order to investigate the sintering behaviours of different types of filler sands (chromite-based, zircon-based, and silica-based) with high-chromium stainless steel grades ( w[Cr] = 11.70% and 16.26%), laboratory experiments were carried out at 1600°C in an inert atmosphere. It is found that the high content of Cr in stainless steel promotes the formation of Cr2O3 in the liquid phase of these sintered filler sands, thereby significantly affecting the sintering of the filler sands. Compared with the elements of Mn and Al in conventional steel grades, the Cr element in stainless steel shows a different impact on the sintering of filler sands. The sintering of chromite-based sands is restricted by the rise of Cr content in stainless steel, whereas the dissolved Cr in the steels enhances the sintering of zircon-based and silica-based filler sands. Chromite-based filler sands are recommended for stainless steel. Because the melting point of the liquid phase is significantly influenced by the content of (Cr2O3 + Al2O3), the contents of Al2O3 and Cr2O3 in chromite-based sands should be accordingly adjusted for stainless steel.