Increasing Exposure Temperature Research Articles

Development of a catalyst based on mixed iron oxides for intensification the production of heavy hydrocarbon feedstocks

In this work, physical modeling of thermal steam treatment of high viscosity oil without and with the addition of a suspended catalyst to the system was performed. The aim of the magnetite effect for the in- situ upgrading in the production of high viscosity oils was to reduce the content of asphalt-resinous compounds and their molecular weight, while significantly increasing the content of saturated and aromatic hydrocarbons. The presence of a catalyst promoted decarboxylation reactions, as indicated by the significant amount of carbon dioxide produced as the catalyst concentration increased. In addition, the produced carbon dioxide decreased the viscosity of the oil and improved the chemical composition of the group. The introduction of a hydrogen donor helped to reduce the formation of aromatic hydrocarbons in the gas phase composition and prevented the polymerization of the produced hydrocarbons. The determination of viscosity-temperature characteristics showed a significant decrease in the viscosity of the obtained products after the catalytic aquathermolysis of oil. Indeed, during the catalytic aquathermolysis, maghemite was reduced to magnetite by the interaction of iron oxide with steam. In parallel, in the presence of a catalyst, with increasing exposure temperature, the content of hydrogen sulfide was reduced and the formation of iron sulfides such as pyrrhotite was observed.

Experimental Investigation of the TRM-to-Masonry Bond after Exposure to Elevated Temperatures: Cementitious and Alkali-Activated Matrices of Various Densities.

Limited research has focused on the effect of high temperatures on the textile-reinforced mortar (TRM)-to-masonry bond. In this study, masonry prisms that were furnished with double-layered TRM strips were tested under shear bond conditions after their exposure to 200 °C and 400 °C for 1 h using the single-lap/single-prism setup. A total of four TRM systems were applied sharing the same type of textile –a dry AR glass fiber one– and different matrices: two cementitious matrices, namely a normal-weight (TRCNM) and a lightweight (TRCLM) one, and two counterpart alkali-activated matrices (TRAANM and TRAALM) based on metakaolin and fly ash. Specimens’ exposure to elevated temperatures did not alter their failure mode which was due to the sleeve fibers’ rupture along with core fibers’ slippage from the mortar. The residual bond capacity of the TRM systems decreases almost linearly with increasing exposure temperature. The alkali-activated textile reinforced mortars outperformed their cement-based counterparts in terms of bond strength at every temperature. All systems retained close to 50% of their original shear bond strength after heating at 400 °C. Per the type of binder, lightweight matrices resulted in either comparable (cement-based systems) or better (alkali-activated systems) heat protection at the TRM/masonry interface.

Post-Fire Behavior of Non-Prismatic Beams with Multiple Rectangular Openings Monotonically Loaded

The main objective of this paper is to study the behavior of Non-Prismatic Reinforced Concrete (NPRC) beams with and without rectangular openings either when exposed to fire or not. The experimental program involves casting and testing 9 NPRC beams divided into 3 main groups. These groups were categorized according to heating temperature (ambient temperature, 400°C, and 700°C), with each group containing 3 NPRC beams (solid beams and beams with 6 and 8 trapezoidal openings). For beams with similar geometry, increasing the burning temperature results in their deterioration as reflected in their increasing mid-span deflection throughout the fire exposure period and their residual deflection after cooling. Meanwhile, the existing openings situation was compounded. The burned NPRC beams were left to gradually cool down under ambient laboratory conditions, and afterward, they were loaded until failure. The influence of temperature on the residual ultimate load-carrying capacity of each beam was studied by comparing these beams with unburned reference beams. Increasing exposure temperature reduces the ultimate strength of solid NPRC beams exposed to temperatures of 400°C and 700°C by about 5.7% and 10.84% respectively. Meanwhile, NPRC beams with trapezoidal openings showed ultimate strength reductions of 21.13% and 32.8% (for beams with 8 openings) and 28% and 34.4% (for beams with 6 openings) under the same burning conditions. The excessive mid-span deflections for these three types of beams were 2%–30.8%, 1.33%–21.8%, and 1.5%–17.4% under the same burning conditions.

Mechanical behavior of carbonated MgO-based Engineered Cementitious Composite (ECC) after high temperatures exposure

Carbonated MgO-based Engineered Cementitious Composite (ECC) has ultrahigh tensile ductility and tight crack width control behavior. However, the expectation of improved fire-resistant has not been confirmed. This study explored the alterations to mechanical and microstructure characteristics of this material after exposure to temperatures up to 500 °C. Material mass loss, compressive strength, tensile strength, strain capacity, and matrix fracture toughness were measured. Scanning electron microscopy, mercury intrusion porosimetry, thermogravimetric analysis, and X-ray diffraction were used to probe the degradation of the cement matrix and fibers. The effect of elevated temperature on carbonated MgO-based ECC was further assessed via examination of the micromechanical behavior of the fiber-matrix. The objective of this research was to assess the performance of carbonated MgO-based ECC exposed to fire hazards. The tensile ductility of carbonated MgO-based ECC was found to be enhanced when exposed to ∼100 °C as compared with those at room temperature ∼20 °C. Further increase in exposure temperature, however, posed a negative impact on the composite compressive strength, ultimate tensile strength, and ability to control crack width. The results provide a useful database for further investigations into carbonated MgO-based ECC for fire safety enhancement.

Effect of thermal exposure on the strength and stress relaxation response of AA-7075-T6 material

Commercial AA-7075-T6 material was subjected to thermal exposure for 60 min in the temperature range 100–300 °C with an interval of 20 °C. There was no noticeable effect of exposure temperature on the yield stress, ultimate tensile stress, and fracture stress in the temperature range 100–200 °C. However, each strength parameter decreased rapidly with the increase in exposure temperature from 200 to 300 °C. This behavior was accounted for in terms of dislocation glide by Orowan mechanism in an atmosphere of semi-coherent ή precipitates (MgZn 2 ) in the main matrix. Stress relaxation at a fixed strain for 1000 s was recorded at various stress levels over the entire stress – strain curve of a given AA-7075-T6 specimen. The stress relaxation rate s increased linearly with the strain ε o at which initial stress σ o was allowed to relax in the specimen. The stress relaxation parameter (d s /d ε o ) varied with exposure temperature in a manner similar to that of the strength parameters. The rate process of stress relaxation in the low-strain region was precipitate – dislocation interaction whereas that in the high-strain region was recovery by cross-slip mechanism. • AA-7075-T6 was thermally exposed for 60 min at 100–300 °C. • Strength parameters remained nearly invariant in the range 100–200 °C. • Strength parameters decreased rapidly with temperature rise from 200 to 300 °C. • Stress relaxation is controlled by precipitate-dislocation interaction at low-strains. • Stress relaxation is controlled by recovery due to cross-slip at high-strains.

Effect of temperature and aging duration on ethylene propylene diene monomer (EPDM) nonmetallic components used in caustic liquid waste transfer lines

Nonmetallic materials are used in waste transfer lines at the United States Department of Energy’s Hanford Site Tank Farm in Benton County, Washington, USA. During use, the ethylene propylene diene monomer (EPDM) inner hose of the hose-in-hose transfer lines (HIHTLs) are exposed to β and γ radiation, caustic solutions as well as high temperatures and high pressures. Aging behavior of specimens of EPDM HIHTLs and dog-bone shaped specimens were evaluated by exposing to a solution of 25% sodium hydroxide (NaOH) at 38 °C, 54 °C and 77 °C for 6 and 12-months as well as water only at 77 °C for 12-months. Tensile strength and burst pressure of the specimens were characterized and compared with the unexposed (baseline) specimens. Both the tensile strength of the EPDM material and the burst pressure of the HIHTLs significantly decreased with the higher temperatures and longer exposure times. Analyses using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) of the HIHTLs and the dog-bone specimens were conducted. Results show that the surface degradation increased with increasing exposure temperature. Penetration of NaOH into the EPDM material also increased with increasing temperature and exposure duration.

Effect of Elevated Temperature on Mechanical Properties of High-Volume Fly Ash-Based Geopolymer Concrete, Mortar and Paste Cured at Room Temperature

This paper presents results from experimental work on mechanical properties of geopolymer concrete, mortar and paste prepared using fly ash and blended slag. Compressive strength, splitting tensile strength and flexural strength tests were conducted on large sets of geopolymer and ordinary concrete, mortar and paste after exposure to elevated temperatures. From Thermogravimetric analyzer (TGA), X-ray diffraction (XRD), Scanning electron microscope (SEM) test results, the geopolymer exhibits excellent resistance to elevated temperature. Compressive strengths of C30, C40 and C50 geopolymer concrete, mortar and paste show incremental improvement then followed by a gradual reduction, and finally reach a relatively consistent value with an increase in exposure temperature. The higher slag content in the geopolymer reduces residual strength and the lower exposure temperature corresponding to peak residual strength. Resistance to elevated temperature of C40 geopolymer concrete, mortar and paste is better than that of ordinary concrete, mortar and paste at the same grade. XRD, TGA and SEM analysis suggests that the heat resistance of C–S–H produced using slag is lower than that of sulphoaluminate gel (quartz and mullite, etc.) produced using fly ash. This facilitates degradation of C30, C40 and C50 geopolymer after exposure to elevated temperatures.

SENSITIVITY OF SWINE CORONAVIRUS TO ACTION OF DIFFERENT TEMPERATURES

Coronavirus infections are currently receiving a lot of attention due to the emergence of the covid-19 pandemic in the world. The search for models with which it is possible to obtain an adequate result to identify the properties of coronaviruses is intensive. For comparison with the results of our experiments, the article also presents data on the duration of preservation of the infectious properties of the SARS-Cov-2 virus by contamination of surfaces made of different materials and at different temperatures.
 We studied the long-term effect on coronavirus, the causative agent of transmissible swine gastroenteritis (TGE), a number of temperatures: + 4ºC, + 25ºC, minus 13ºC, minus 20ºC and thirteen-fold change in temperature, which was in the range of 31-33ºC. It was found that both vaccine and epizootic strains of TGE coronavirus after long-term storage reduce the infectious properties, but when in contact with a sensitive biological system (in vitro) quickly enough (in the case of successive passages in this system) restore them. We proved that the TGE coronavirus during storage for more than two years reduced, but did not lose infectious properties at temperatures minus 13ºC, minus 20ºC, which were restored during subsequent passage in sensitive biological systems in vitro. The same trend was observed for storage of the virus for 8 years at a temperature of + 4ºC. The fastest decrease in coronavirus titer occurred at a temperature of + 25ºC, but more stable under these conditions was the epizootic strain of the virus, which requires attention when working with field isolates of coronavirus.
 The general tendency of animal and human coronaviruses to decrease the survival time of the pathogen with increasing exposure temperature has been established. Resistance of the virus to repeated sharp changes in temperature (from minus 13 ± 0.5°C to room temperature) without loss of infectious properties was revealed.

Evaluation on the Bond Capacity of the Fire-Protected FRP Bonded to Concrete Under High Temperature

To figure out the change in the reinforcing effect of FRP system used for the retrofit of RC beam when it is exposed to high temperature, it is required to evaluate not only the behavior of the entire beam, but also the bond performance at anchorage zone through a bond test according to the increase of external temperature. Moreover, the study to find various fire-protection methods is necessary to prevent the epoxy from reaching the critical temperature during an exposure to high temperature. In this manner, the fire-resistance performances of externally bonded (EB) FRP and near-surface-mounted (NSM) FRP to concrete block were evaluated by high-temperature exposure tests after performing a fire-protection on the surface in this paper. Board-type insulation with mortar was considered for the fire-protection of FRP system. After the fire-protection of the FRPs bonded to concrete blocks, an increasing exposure temperature was applied to the specimens with keeping a constant shear bond stress between concrete and the FRP. Based on the result, the temperature when the bond strength of the FRP disappears was evaluated. In addition, a finite element analysis was performed to find a proper method for predicting the temperature variation of the epoxy which is fire-protected with board-type insulation during the increase of external temperature. As a result of the test, despite the same fire-protection, NSM specimens were able to resist 1.54–2.08 times higher temperature than EB specimens. In the design of fire-protection of FRP system with the board-type insulation, it is necessary to consider the transfer from sides as well as the face with FRP. If there is no insulation of FP boards on the sides, the epoxy easily reaches its critical temperature by the heat penetrated to the sides, and increasing the thickness of the FP board alone for the face with FRP does not increase the fire-resistance capacity. As a result of the FE analysis, the temperature variation at epoxy can be predicted using the analytical approach with the proper thermal properties of FP mortar and board.

Mechanical Behavior of Steel Fiber-Reinforced Lightweight Concrete Exposed to High Temperatures

The mechanical characteristics of steel fiber-reinforced lightweight concrete (SFLWC) under high temperatures are studied in this paper. Different concrete matrices, including all-lightweight concrete (ALWC) and semi-lightweight concrete (SLWC), and different steel fibers with hooked ends and crimped shapes are considered as objects. In addition, normal-weight limestone aggregates concrete (NWC), no-fiber ALWC, and SLWC were tested after high-temperature treatment as a control group. The temperature effects on the splitting tensile strength, ultrasonic pulse velocity, compressive stress–strain curve, elastic module, peak strain, and axial compressive strength of the SFLWC were investigated. The results showed that, with increasing exposure temperature, both the axial compressive strength and the elastic modulus decreased, while the axial peak strain has a certain increase, and hence the stress–strain curves were gradually flattened. The toughness of all the concretes increased first and then reduced with increasing temperature, while the specific toughness of all the concretes increased with the increase in temperature. Compared with NWC and SLWC, ALWC had a better capacity to resist high temperatures, especially temperatures > 400 °C. Adding steel fibers can improve the capacity of energy absorption, specific toughness, and residual splitting tensile strength of lightweight concrete (LWC) before and after it is exposed to high temperatures. Based on a regression analysis, a segmented constitutive equation for LWC and SFLWC under uniaxial compression was derived from fitting the experimental findings, and the fitting curve agrees well with the test results.

Effect of water diffusion and thermal coupling condition on SBS modified asphalts’ surface micro properties

Moisture damage is a particular concern for asphalt aging during the service life of asphalt mixture and pavement. At present, the microscopic research of the surface morphology, mechanical property and chemical composition of SBS modified asphalts under the water diffusion and thermal coupling condition is lacking. In order to characterize the effect of water diffusion-thermal condition on surface micro properties and moisture sensitivity of SBS modified asphalts, atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) were used in this paper. Both SBS modified and Pen70 asphalts showed the similar evolution under the water diffusion-thermal coupling condition from AFM images. FTIR tests confirmed that the polar compounds increased and SBS polymer decreased in SBS modified asphalts. Meanwhile, the increasing exposure temperature would accelerate the evolution of the chemical composition and surface structure. What’s more, combined with AFM and FTIR tests results, it was found that the formation of microstructure and the micromechanical properties were closely related to the chemical functional group indexes. The ratio of modulus between wet-conditioned sample and dry sample was proposed to evaluate the SBS modified asphalts’ moisture-thermal sensitivity. The interactions between polar compounds with water molecules and the reduction of SBS polymers were collectively responsible for the arise of the surface modulus and moisture-thermal sensitivity of SBS modified asphalt. In addition, the diffusion of water in asphalt films followed Fick’s second law. It was found that the water molecules diffused slower in SBS modified asphalt, which might be associated with the interaction between water molecules and SBS modifier.

Fracture behaviors of concrete incorporating different levels of recycled coarse aggregate after exposure to elevated temperatures

This study focuses on the fracture behavior of recycled aggregate concrete (RAC) after exposure to elevated temperatures, thus, a total of 128 cubic specimens and 64 notched beams were cast to analysis the effects of recycled coarse aggregate (RA) substitutions (0%, 30%, 70% and 100%) and elevated temperatures (20 °C, 100 °C, 200 °C and 300 °C) on fracture parameters of RAC, such as peak load (Pmax), critical crack mouth opening displacement (CMODc), critical crack tip opening displacement (CTODc), effective crack length (ac), fracture energy (GF), initiation fracture toughness (KICini), unstable fracture toughness(KICun), the characteristic length (Lch) and so on. The result showed that the values of Pmax decreased as the increase of exposure temperature and the decrease rate grew slower as the increase of RA substitution. In contrast, the values of GF increased with elevated temperature and the increased rate grew slow with the incremental of RA replacement. As the increase of RA substitution, the CMODc and CTODc of specimens slightly increased first and then decreased at ordinary temperature and elevated temperature. The KICini and KICun of concrete with different RA substitution decreased with the elevated temperatures. In addition, the RA substitution had a positive impact on the KICini of concrete after exposure to 200 °C and 300 °C. At each high temperature, the Lch of RAC was smaller than that of natural aggregate concrete (NAC), indicating that the ductility of RAC was worse than that of NAC.

Effect of thermal exposure on the microstructure and creep properties of a fourth-generation Ni-based single crystal superalloy

The effect of thermal exposure on microstructure and creep properties of a fourth-generation nickel-based single crystal superalloy was investigated. The thermal exposure of samples after the full heat treatment was carried out at 1000 °C, 1100 °C and 1140 °C for 100 h and 200 h. The γ′ coarsening, γ′ rafting and γ channel widening were observed in samples after thermal exposure. When the thermal exposure time was constant, the morphology of γ′ phase in the alloy evolved significantly with increasing aging temperature. The interfacial dislocation networks in aged samples after creep ruptured gradually became irregular and sparse with the increase of exposure temperature. When the higher exposure temperature was used, enlargement of the defect pores was observed in samples, the microcracks were more likely to initiate and propagate at the corner of these pores. After aging at 1000 °C for 100 h, the creep life at 1140 °C/137 MPa was slightly longer than that of heat-treated sample, which could be attributed to the slightly coarsened γ′ phase, homogenization of refractor elements. In contrast, the creep life of sample exposed at 1140 °C for 100 h was greatly decreased. The decrease of creep life was dominated by the rafting of γ′ phase, the irregular interfacial dislocation networks as well as the enlargement of homogenization pores.

Liquid Metal Corrosion Studies for Fusion Reactor Applications: Facility Development and Basic Research

In the present research work, under different operating conditions, the corrosion behavior of the Indian RAFMS (IN RAFMS: 9Cr-1.4 W) and its surrogate material, modified 9Cr-1Mo steel (P91) in molten Pb–Li has been investigated using a number of specially developed test facilities offering isothermal and non-isothermal (under static and flowing) conditions. The diffusion of Fe across the Pb–Li boundary layer has been established to be the rate-controlling step in the case of IN RAFMS. Increase in temperature of exposure, flow velocity, and presence of a temperature gradient increases the attack of Pb–Li. Corrosion of ferritic/martensitic steels in Pb–Li is generally initiated by the dissolution of air-formed oxide layer which consisted of oxides of Fe and Cr. This accounts for an initial period of initial retarded corrosion rate which is termed as “Incubation period’ during which grain boundary penetration of Pb–Li was the dominating mode of corrosion. The mode of Pb–Li attack is changed with the dissolution of the oxide layer resulting in higher rates of corrosion.

Effect of high-temperature supercritical carbon dioxide exposure on the microstructure and tensile properties of diffusion-bonded Alloy 690

Alloy 690 was diffusion-bonded and exposed to the high-temperature supercritical CO2 environment, and the effect of exposure on the microstructure and mechanical properties was investigated. In the as-bonded joint, some small carbides are discontinuously arranged along the bonding line. After exposure at 550 °C and 600 °C, the continuous carbides are developed and occupy all the grain boundaries and bonding line. The continuous carbides transform into the discrete large particles when the exposure temperature further increases to 650 °C. With the increase in exposure temperature, the tensile strength and microhardness of the joints decrease, while the elongation first slightly increases and then decreases at 650 °C. For the as-bonded joint and the joints exposed at 550 °C and 600 °C, the fracture occurs at the parent Alloy 690 and the main fracture mode is the ductile dimple fracture. However, for the joint exposed at 650 °C, the fracture occurs at the bond line with a manner of brittle fracture. The degradation of strengths and elongation after exposure to supercritical CO2 at 650 °C were associated with the growth of carbides along the bond line.

Oxide film prepared by selective oxidation of stainless steel and anti-coking behavior during n-hexane thermal cracking

In order to reduce coke formation on the substrate surface, selective oxidation pre-treatments were systematically assessed for 316L stainless steel under H2-H2O atmospheres at 650 °C–950 °C and 0.1 MPa for 10 h. The phase constitution, elemental composition and surface morphology of oxide films were characterized by a combination of SEM, XRD, and EDS. The results showed that the oxidation temperature had a great influence on the morphology and microstructure of oxide films. The Mn and Cr content on the metal surface gradually increased with the increasing exposure temperature. The element composition was mainly associated with MnCr2O4 and Cr2O3. Thickness of oxide films was evaluated in various conditions. The anti-coking performance was evaluated by the n-hexane thermal cracking. It was found that the amount of the coke deposited on the oxidized tube was much smaller than that on the untreated tube, with an average anti-coking ratio of 83.2%. Moreover, the morphologies of carbon deposits were mainly filamentous on the inner surface of untreated tube, but granular for the case of the oxidized tubes.

Coupled effects of high temperature and strain rate on compressive properties of hybrid fiber UHTCC

This study investigates the combined effect of the strain rate and temperature on the compressive properties of hybrid fiber ultra high toughness cementitious composites (UHTCCs) using a Split Hopkinson pressure bar. Specimens were first heated to different exposure temperatures, e.g. ambient temperature, 200, 400, 500, 600 and 800 °C, and subsequently, cooled to ambient temperature. Thereafter, the specimens were tested at four different strain rates. The test results show that the dynamic compressive strength of the UHTCC is enhanced at a temperature of 200 °C, and subsequently, decreases with the increase in exposure temperature. The strain rate sensitivity of UHTCC is largely enhanced with the increase in exposure temperature. The possible mechanism of this phenomenon was discussed based on the high-speed photography of the crack propagation process on the surface of the specimens and microscopic observation of fibers condition on their fracture surfaces. Moreover, an empirical relationship is established to express the dynamic strength enhancement of fire-damaged UHTCC as a function of strain rate.

The Effect of Ordinary Portland Cement Substitution on the Thermal Stability of Geopolymer Concrete.

The influence of using cement on the residual properties of fly ash geopolymer concrete (FAGC) after exposure to high temperature of up to 800 °C was studied in terms of mass loss, residual compressive strength and microstructure. The mass loss was found to increase with the increase of exposure temperature, which is attributed to vaporization of water and dehydroxylation of sodium aluminosilicate hydrate (N-A-S-H) gels. The dehydroxylation of calcium silicate hydrate (C-S-H) gels and the disintegration of portlandite were responsible for higher mass loss ratio of FAGCs containing cement. The results showed that cement could increase compressive strength of FAGCs up to 200 °C, after which a significant reduction in residual strength was observed. It was found that FAGCs without cement yielded higher residual strength than the original strength after heating up to 600 °C. The observed increase of compressive strength up to 200 °C was attributed to the secondary geopolymerization which was evidenced in the scanning electronic microscopy (SEM) images.

Microstructural Change and Fracture Behavior under Different Heat Exposure Conditions on Thermal Barrier Coatings Deposited on TiAl Intermetallic Compound

Air plasma sprayed thermal barrier coatings (APS-TBCs) deposited on the TiAl intermetallic compounds was heat exposed in air at different temperatures and times to evaluate the microstructural change and delamination behavior. The thermal barrier coating (TBC) layer, bond coat (BC) layer and substrate were composed of 4 mol% Y2O3 stabilized ZrO2, CoNiCrAlY alloy (Co-32Ni-21Cr-8Al-0.5Y (mol%)) and TiAl intermetallic compound (Ti-46Al-7Nb-0.7Cr-0.2Ni-0.1 Si (mol%)), respectively. Due to the heat exposure, diffusion of the elements occurred between the BC layer and the substrate, and diffusion layers were formed on both the BC layer and the substrate. A thermally grown oxide (TGO) layer was formed between the TBC layer and the BC layer. The thickness of the TGO layer and the diffusion layer increased with increasing exposure temperature and time. In the TBCs heat exposed at 1273 K for 200 h, a composite oxide of Al2O3 and TiO2 was formed in the BC layer. Regarding the TBCs which were as-deposited and heat exposed at 1073, 1173 K up to 200 h and at 1273 K for 10 h, delamination occurred in the TBC layer near the BC layer. In the TBCs exposed at 1273 K for 50 h or more, delamination occurred at the vicinity of the interface between diffusion layer on the substrate side and the unreacted side of the substrate too. In case that the TBCs were heat exposed at 1073 and 1173 K, the shear strength decreases after reaching the maximum value of the shear strength at 10 h heat exposure. When the TBCs were exposed to heat at 1273 K, the shear strength indicated a constant value after the shear strength increased up to 50 h. This change may be due to the change in crack path after exposure for 50 h at 1273 K.

Synthesis of Ti2AlN MAX-phase by sintering in vacuum

The dependence of MAX-phase synthesis on phase composition of the initial mixture and heat treatment terms in the electric furnace was investigated. Using Ti and AlN powders with the molecular ratio 2:1 as an example, the sequence of phase composition changes with increasing exposure temperature was tracked. It was established that the maximum amount of Ti2AlN MAX-phase in the end products is obtained at 1400°C. At this temperature a single phase product (100% wt Ti2AlN) was obtained for the initial mixture Ti:Al:TiN = 1:1:1. The principal possibility of scaling for obtaining a single-phase product of Ti2AlN by vacuum sintering was experimentally shown on the example of the mixture of this composition weighing 500 g at a certain mode of thermal vacuum treatment.