Subsequent High-temperature Treatment Research Articles

Interlaced stacked hollow Cu2O dendrite for stable lithium metal anode

The stable operation of lithium metal batteries faces hindrances due to the persistent issue of uncontrolled lithium dendrite growth. In this study, we present a facile approach wherein 3D structured cuprous oxide (Cu2O) dendrites are constructed on flat copper foil through a straightforward process involving electrodeposition and subsequent high-temperature treatment. The thin lithium oxide (Li2O) layer stemming from lithiophilic Cu2O further establishes a conducive channel for the swift diffusion of lithium ions (Li+) at the solid-liquid interface. Notably, the staggered stacking of Cu2O dendrite results in a 3D structure with a significantly enlarged specific surface area, which not only mitigates current density but also promotes a uniform distribution of Li flow. The proposed Cu2O electrode yields superior performance, achieving a Coulombic efficiency of up to 98.2% and a sustained lithium deposition/stripping process lasting an impressive 880 h. In the full cells, employing Li/Cu2O dendrite electrode, an exceptional Coulombic efficiency (CE) of 99.9% is attained after 160 cycles at 1C, coupled with an admirable capacity retention rate of 84%. These findings underscore the promising potential of the Cu2O dendrite electrode for advancing the practical applications of lithium metal batteries.

Understanding the Increase in H2/Air PEM Fuel Cell Performance of Pt Based Cathode Catalysts with the Tailored Pore Structure of Mesoporous Graphitic Spheres

To reach its climate neutrality goal by 2050, the European Union has agreed on ceasing the sale of new petrol and diesel-driven vehicles by the end of 2035. Therefore, interest in carbon-neutral transport options, such as battery-electric vehicles (BEV) or fuel-cell-electric vehicles (FCEV) has tremendously increased. Especially for heavy-duty applications, proton exchange membrane fuel cells (PEMFCs) can be a viable solution, as they exhibit a higher gravimetric power density compared to BEVs.[1] However, cost and supply constraints of the catalyst active material, i.e. platinum, are still a major hurdle to make PEMFCs competitive with incumbent technologies. While this has been addressed by a reduction of the Pt loading, this induces some major drawbacks regarding the overall performance due to the decrease in catalyst activity towards the oxygen reduction reaction (ORR) and the increase in proton and oxygen mass transport resistances to the Pt surface.[2] It has been shown that those issues can be mitigated by using cathode catalyst materials with a mesoporous carbon support, as they exhibit a high ORR activity while additionally facilitating the transport of protons and gaseous oxygen to Pt nanoparticles that are located inside the pores of the carbon support particles.[3] Previous studies have demonstrated that by using a multi-step catalyst synthesis procedure where Pt nanoparticles are incorporated into a mesoporous graphitic sphere (MGS) support and subjected to a pore-confined growth by a subsequent high-temperature treatment, a precisely defined catalyst structure is achieved with a good H2/air performance as well as high stability towards catalyst degradation.[4] In order to correlate the impact of a precisely defined mesoporous carbon structure on the overall H2/air performance, single cell tests were performed using 5 cm2 membrane electrode assemblies (MEAs) with cathode loadings of 0.1 mgPt cmMEA -2 using different commercially available 20 wt.% Pt/C catalysts as well as a 28 wt.% Pt/C catalyst based on lab-scale synthesized carbon supports: i) Ketjen black (KB, TEC10E20E, TKK); ii) Vulcan (Vu, TEC10V20E, TKK); and, iii) mesoporous graphitic spheres (MGS). The latter was produced following the procedure by Knosalla et al.[5] A full MEA characterization was included to measure the electrochemically active surface area (ECSA) by CO-stripping, the H2/air performance at different operating conditions (high and low relative humidity and high pressure), the H2/O2 performance, and the O2 and H+ transport resistance in the cathode by limiting current measurements and electrochemical impedance spectroscopy (EIS), respectively. Finally, the catalyst morphology has been studied ex/situ using three/dimensional reconstruction by electron tomography and by gas adsorption measurements (argon at 87 K and water at 298 K).It was found, that the mesoporous carbon support significantly improves the H+ and O2 transport, resulting in an improved H2/air performance compared to both commercial catalyst materials (see. Fig. 1 MGS vs. KB or Vu). Interestingly, the MGS retains also a high ORR catalyst mass activity (imass ≈ 400 A/gPt) which is similar to the one of Pt/KB cathode catalysts (with higher internal microporous structure), leading to the good H2/air performance also at low current densities. The overall optimal performance of Pt/MGS suggests that these materials have a defined porous internal network structure which combines the beneficial effect of a facilitated O2 and H+ transport through larger mesopores while still shielding the Pt surface from ionomer contact by incorporation of Pt nanoparticles into smaller micropores.

Universal pathway towards metal sulfides decorated 3D porous Ti3C2Tx MXene aerogel for vapor-phase mercury removal

Utilization of monolithic mineral sulfide-based sorbent for the fix-bed elemental mercury (Hg0) removal is regarded as a predominant predicament in the field of Hg0 abatement. In this work, a general and facile route was exploited to establish CuS particles decorated 3D porous Ti3C2Tx MXene aerogel via divalent Cu2+ cations induced assembly combined with subsequent high-temperature sulfurization treatment, during which, uniform CuS particles were homogeneously anchored throughout the Ti3C2Tx substrate. The obtained 3D CuS/Ti3C2Tx MXene aerogel exhibited satisfactory textural property, hierarchical pore structure and strong interaction between Ti3C2Tx MXene and CuS. Meanwhile, the inherent restacking of Ti3C2Tx MXene nanosheet and serious agglomeration of CuS can also be effectively avoided in the formation of aerogel. Those structural advantages originating from this novel gelation process favorably contributes to satisfactory Hg0 mass transfer and sufficient utilization of CuS active ligands, which largely strengthens Hg0 removal performance and broadens the fix-bed application of mineral sulfides. Consequently, the Hg0 capture capacity and adsorption rate of CuS/Ti3C2Tx MXene aerogel reached 90596.4 g m−3 and 120.64 g m−3 min−1, respectively, far outbalancing those of the reported in-situ selenized copper foam with excellent Hg0 removal activity. The impressive Hg0 sequestration performance is attributed to its relatively large specific surface area, layered pore channel, and highly dispersed CuS particles, largely boosting Hg0 mass transfer and following sequestration. Moreover, other mineral sulfides/Ti3C2Tx MXene aerogels can also be constructed by just replacing divalent metal cations, which makes the initial effort towards the fix-bed utilization of mineral sulfides-based aerogel for vapor-phase Hg0 immobilization.

Corn-straw-converted activated carbons with tunable porosity and N/O functionalities as high-performance supercapacitors electrode at commercial-level mass loading

With the scientific importance and industrial need for low-cost but high-performance activated carbons (ACs) for supercapacitors (SCs), ACs with tailorable porous texture and heteroatom doping are turned from corn straw via hydrothermal and activation processes. Porous texture is mainly adjusted by KOH/biochar mass ratio. O and N surface functionalities are tuned by a subsequent high-temperature treatment by H2O or ammonia. The influences of porosity in the amounts of the introduced N contents are investigated. With symmetric SC cells, the electrochemical performances of the corn-straw-derived ACs are examined at commercial-level mass loading. For aqueous electrolyte, the ACs prepared without KOH activation but with high-temperature treatment by ammonia exhibit high gravimetric capacitance of 192 F/g and volumetric capacitance of 150 F/cm3 due to their high compact density and N atomic fraction. For organic system, the optimum ACs are activated with KOH/biochar ratio of 1:1 and a subsequent ammonia high-temperature treatment, which deliver high gravimetric capacitance of 258 F/g and volumetric capacitance of 167 F/cm3. Balanced porosity and density, low O fraction but high N fraction are found to be favored for organic system. The cost-effective technique route may provide guidance for the design and preparation of biomass-derived ACs with tunable porosity and heteroatom functionalities for practical applications in SCs.

Cobalt-based zeolitic imidazole framework incorporated with well-dispersed bimetallic nanoparticles/ions as a multifunctional nanozyme for the degradation of environmental pollutants and discrimination of various phenolic substances

Several strategies, such as increasing catalytic active sites, doping another element, and designing hybrids, have been used to enhance the catalytic efficiency of the nanozyme for the efficient degradation of pollutants, sensitive analysis, and effective disease therapy. However, multifunctional nanozyme catalysts from a single MOF precursor with improved catalytic activity lack systematic research. Here, we have developed six nanozyme composites from a cobalt-based zeolitic imidazole framework (ZIF-67) as a precursor by doping metal ions (Ni2+ or Cu2+, or Fe2+) and subsequent high-temperature treatment. It is found that three kinds of metal ions-doped ZIF-67 and their corresponding high-temperature pyrolysis exhibit three kinds of catalytic activity including peroxidase-like, oxidase-like, and pollutant-reduced degradation nanozyme. Firstly, the degradation rate of pollutant substrates is increased by more than 13.3 times by doping metal ions (Ni2+ or Cu2+, or Fe2+) in ZIF-67. Moreover, a more than 96.3-fold enhancement is achieved by integrating doped-metal ions and pyrolysis of ZIF-67. Secondly, the oxidase-like activity of decorated-metal ions (Ni2+ or Cu2+, or Fe2+) ZIF-67 is enhanced by more than 300%. Thirdly, it is found that the reactive oxygen intermediate species (ROS) including singlet oxygen (1O2) and superoxide anion (•O2–) are produced by the oxidase-like reaction. Finally, we have proposed a facile and high-performance sensor array for colorimetric quantification and discrimination of nine phenolic pollutants and five biological molecules at no less than 2.0 μM by employing three decorated-metal ions ZIF-67 composite as the oxidase-like nanozyme. Ultimately, the colorimetric array sensor has great potential application prospects in monitoring environmental phenolic pollutants and disease diagnosis.

Fe2P nanoparticle-decorated carbon nanofiber composite towards lightweight and highly efficient microwave absorption.

An Fe2P nanoparticle (Fe2P NP)-decorated carbon nanofiber (represented as Fe2P@CNF) composite was in situ prepared by electrospinning and subsequent high-temperature treatment. Benefitting from the synergy effect between Fe2P NPs and CNFs, as well as improved interface polarization and impedance matching, the Fe2P@CNF composite exhibits excellent microwave absorption performance relative to pure CNFs, in which the Fe2P@CNF composite with a fill loading of only 10 wt% possesses a minimum reflection loss (RL) of -49.2 dB at 3.0 mm and a maximum effective absorption bandwidth of 6.0 GHz at 2.2 mm. Therefore, this work provides a promising approach for the design and synthesis of an Fe2P@CNF composite with high-performance microwave absorption.

Формирование интерметаллического покрытия Ni-=SUB=-3-=/SUB=-Al холодным газодинамическим напылением механически обработанной в планетарной мельнице порошковой смеси Ni-Al

The features of the formation of an intermetallic Ni3Al coating by cold spraying of a Ni–Al powder mixture mechanically treatment in a planetary mill and prepared in a V-shaped mixer are presented. It is shown that the powder deposition efficiency is 1.5 times higher when coatings are obtained from a mechanically treated powder mixture of Ni and Al components. Subsequent high-temperature treatment in the furnace chamber creates a condition for the formation of an intermetallic compound of the Ni-Al system of various stoichiometric proportions.

Formation of an intermetallic Ni-=SUB=-3-=/SUB=-Al coating by cold spraying of a Ni-Al powder mixture mechanically processed in a planetary mill

The features of the formation of an intermetallic Ni3Al coating by cold spraying of a Ni-Al powder mixture mechanically processed in a planetary mill and prepared in a V-shaped mixer are presented. It is shown that the powder deposition efficiency is 1.5 times higher when coatings are obtained from a mechanically treated powder mixture of Ni and Al components. Subsequent high-temperature treatment in the furnace chamber creates a condition for the formation of an intermetallic compound of the Ni-Al system of various stoichiometric proportions. Keywords: cold spray, composite material, high-energy planetary mill, nickel, aluminium, titanium nitride, X-ray analysis.

Study of the structure and mechanical properties of composites used in the oil and gas industry

<abstract> <p>This article describes the structure and properties of the developed hybrid composite Hastelloy X (NiCrFeMo)-AlMoNbTaTiZr-cBNSiCNiAlCo. The composite was obtained by the high velocity oxygen fuel spraying (HVOF) method in a protective atmosphere with a subsequent high-temperature thermomechanical treatment. In order to obtain new information about the structure, we studied the metallophysical properties of the composite using electron microscopy and X-ray diffraction analysis, as well as the mechanical properties and phase composition. We studied the influence of high-energy mechanical processing of high-entropic and ceramic materials on the structural-phase state and composite quality. We determined the optimal technological parameters of HVOF in a protective atmosphere, followed by a high-temperature thermomechanical treatment. Additionally, we optimized these parameters to form a hybrid composite providing the highest adhesion and low porosity. Moreover, we investigated the microhardness of the composite layers. On the basis of complex metallophysical studies, we examined the composite formation. In order to determine the endurance limit in comparison to various other composite materials, we carried out cyclic endurance tests of the developed materials.</p> </abstract>

Producing high-purity zinc oxide for photonics technologies

The authors developed a procedure for synthetizing high-purity zinc oxide by precipitation from a solution with the subsequent high-temperature treatment in oxygen. Metallic zinc additionally purified by vacuum distillation, nitric acid and aqua ammonia with total impurities not exceeding 10–4 % wt. were used as incoming substances for the synthesis. It is found that to produce a single-phase product as zinc oxide powder containing no nitrate and amine complexes, the precipitation should be conducted at a zinc concentration in solution of 2 mol/l and pH = 7.5. Impurities of iron, chromium, aluminum, barium, molybdenum and sodium are removed at the stage of forming the intermediate precipitate at pH = 5. The yield of the final high-purity product is 59%. A scanning electron microscopy method was used to study precipitate morphology before high-temperature annealing and after it. It is shown that the final product is powder formed from well-faceted crystallites represented by hexagonal prisms, 0.5–0.7 μm in diameter and 1.7–2.1 μm in length. The analysis of luminescence spectra indicated that synthetized and purified ZnO after high-temperature annealing showed low luminescence with a maximum value of 678 nm, while commercial ZnO powder was characterized by intensive luminescence with a maximum value of 522 nm, attributed to defects of non-stoichiometry and/or yttrium impurities. Chemical purity of zinc oxide synthetized and purified according to the developed procedure, as shown by inductively coupled plasma mass spectrometry, was 99.9993 % wt. by 67 impurity elements.The authors acknowledge K. I. Runina, an employee of the Department of Chemistry and Technology of Crystals, for her help with spectral studies.The research was conducted as part of funding applied research project of Mendeleev University of Chemical Technology of Russia No. ВИГ 2022-081.

Some features of the surface modification of MgO–Al2O3–TiO2–SiO2 glass and glass ceramics by Ag diffusion

Diffusion of Ag species into the surface layers of the MgO–Al 2 O 3 –TiO 2 –SiO 2 glass stimulates the crystallization processes therein during subsequent thermal treatment. It was found that the silver doping significantly increases the microhardness of glass and glass ceramics. The effect of the Ag diffusion and the subsequent high-temperature treatment (T > T g ) on the structure and luminescence properties of the MgO–Al 2 O 3 –TiO 2 –SiO 2 glass was studied. The thermal evolution, structure and properties of the glass and glass ceramics were investigated by the DSC method, XRD analysis and luminescence spectroscopy. It was found that the Ag diffusion into the surface layers leads to the formation of numerous different luminescent molecular Ag n clusters. The MgO–Al 2 O 3 –TiO 2 –SiO 2 glass and glass ceramics subjected to the Ag diffusion can operate as effective down-converters of the radiation demonstrating the effective transformation of UV and blue light into the radiation of red and NIR spectral range.

Macro-encapsulated metallic phase change material over 1000 °C for high-temperature thermal storage

This study reports the successful fabrication of Cu@Al 2 O 3 macro-encapsulated metallic PCMs for high-temperature thermal storage over 1000 °C. Cu powders are employed as raw material which are spherulitized to core balls in millimeter-size, and subsequently the core balls are cladded with Al 2 O 3 ceramic shells. After the low-temperature pre-sintering and subsequent high-temperature sintering treatment, the Cu@Al 2 O 3 macrocapsules which contain gaps between the shells and cores are successfully prepared. The core balls are consisted of Cu powders which are not densified but are porous, offering buffer spaces to accommodate the thermal volume expansion during high-temperature sintering and melting of Cu. As a comparison, Cu@Al 2 O 3 macrocapsules prepared by directly coating the commercial solid Cu balls are leaky. Thermal analysis indicates that the metallic core PCM has a melting temperature of 1063 °C and a latent heat of around 210 J/g. The macrocapsules are also highly durable as confirmed by the melting-solidification cycling test. These results demonstrate that the Cu@Al 2 O 3 macrocapsules are applicable as high-temperature heat storage media, which can find useable applications in advanced high-temperature thermal energy storage systems. • This work reports the successful fabrication of Cu@Al 2 O 3 macro-encapsulated PCM over 1000 °C. • The capsules contain buffer gaps between shell and core to accommodate the thermal volume expansion. • The PCM core has a melting temperature of 1063 °C and a latent heat of around 210 J/g. • The macrocapsules were highly durable in the melting-solidification cycling test.

Sulfur & nitrogen co-doped electrospun carbon nanofibers as freestanding electrodes for membrane capacitive deionization

Capacitive deionization (CDI), especially membrane capacitive deionization (MCDI) technology, is an energy-efficient and environmentally friendly water desalination technology. Tremendous efforts have been devoted to designing and preparing high-performance and applicable electrode materials for CDI and MCDI. In this work, sulfur and nitrogen co-doped carbon nanofibers (SCNFs) are prepared by a facile co-electrospinning strategy coupled with subsequent high-temperature heat treatment, and directly used as monolithic and binder-free electrodes for MCDI. Benefiting from the integrated structural and compositional merits, i.e. 3D network composed of disorderly stacked 1D nanofibers and uniform distribution of nitrogen and sulfur atoms, the as-obtained SCNFs exhibit superior electrosorption ability and excellent cycling stability, with the salt adsorption capacity up to 29.50 mg g−1 and the current efficiency higher than 80% when desalting 500 mg L−1 NaCl solution at the voltage of 1.4 V. The doped nitrogen and sulfur atoms in SCNFs not only effectively improve their electrical conductivity and wettability but also tailor the pore structure, thus providing more active sites for ions adsorption. The heteroatom doping strategy could shed new light on the design of high-performance carbon-based electrodes for the electrochemical MCDI application.

Preliminary Study on the Mechanical Activation and High-Temperature Treatment of Saponite-Containing Tailings Generated during Kimberlite Ore Dressing

This study investigates transformations of a pre-mechanically activated saponite-containing material with subsequent high-temperature treatment. The thermogravimetric analysis confirmed that the mechanical activation of saponite leads to the destruction of its layered structure, accompanied by the release of silicon dioxide and magnesium oxide in free form. The values of surface activity for mechanically activated saponite-containing material are also calculated. It is shown that when mechanically activated saponite-containing material is mixed with water, minerals of the serpentine group are formed, and further high-temperature treatment leads to the formation of minerals of the olivine group. It is experimentally shown that high-temperature treatment leads to the creation of a more durable structure of the saponite-containing material. This is due to decreased porosity and pore size, and sorption of moisture from the environment is also reduced. The study showed that saponite-containing waste materials can be effectively treated to create composite materials based on magnesia binders. Thus, with this method, the waste is effectively recycled into various green building material and can be used as supplementary cementitious material or fine aggregate replacement in concrete.

STUDY OF WEAR RESISTANCE OF LAYERED METAL-INTERMETALLIDE COMPOSITES OF THE TI-FE SYSTEM

The paper presents the results of wear tests for the SMIC of the titanium - iron system, obtained by the technology, including explosion welding and subsequent high-temperature heat treatment, when the abrasive is exposed to the metal-intermetallic layers at an angle of 0, 45 and 90º. It is shown that more uniform wear is observed when an abrasive is applied to the layered structure of SMIC at an angle of 45º. With such a wear pattern, the best indicators of wear resistance are provided, exceeding the corresponding values for 08kp steel and VT1-0 titanium, and having a tendency to increase with increasing test temperature: +7% at 200 °C; + 13% at 400 °C and + 17% at 600 °C.

Chemical Stability and Ionic Conductivity of LGPS-Type Solid Electrolyte Tetra-Li7SiPS8 after Solvent Treatment

The large-scale production of solid-state batteries necessitates the development of alternative routes for processing air-sensitive thiophosphate-based solid electrolytes. To set a basis for this, we investigate the chemical stability and ionic conductivity of the LGPS-type lithium-ion conductor tetra-Li7SiPS8 (LiSiPS) processed with various organic solvents. We elucidate the nature of colorful polysulfides that arise during solvent treatment and trace back their origin to the dissolution of the Li3PS4-type amorphous side phase typically present in LiSiPS. We find that water and alcohols decompose LiSiPS by the nucleophilic attack into oxygen-substituted thiophosphates and thioethers and propose a reaction mechanism for the latter. Moreover, we confirm that quaternary thiophosphates can be recrystallized from MeOH solutions upon subsequent high-temperature treatment. Aprotic solvents with donor numbers smaller than 15 kcal mol–1 are suitable for wet-processing quaternary thiophosphates because both the crystal structure of the electrolyte and a high ionic conductivity of >1 mS cm–1 are retained. Using anisole as a case study, we clarify that a residual water content of up to 800 ppm does not lead to a significant deterioration in the ionic conductivity when compared to dry solvents (≤5 ppm). Additionally, we observe a decrease in ionic conductivity with an increasing amount of the solvent residue, which depends not only on the donor number of the solvent but also on the vapor pressure and interactions between the solvent molecules and thiophosphate groups in the solid electrolyte. Thus, optimization of solvent-processing methods of thiophosphate electrolytes is a multifaceted challenge. This work provides transferable insights regarding the stability of LiSiPS against organic solvents that may enable competitive and large-scale thiophosphate-based solid electrolyte processing.

Phase evolution of Te-hyperdoped Si upon furnace annealing

Si hyperdoped with chalcogens via ion implantation and pulsed laser melting is known to exhibit strong room-temperature sub-bandgap photoresponse. As a thermodynamically metastable system, an impairment of the optoelectronic properties in hyperdoped Si materials occurs upon subsequent high-temperature thermal treatment (>500 °C). The substitutional Te atoms that cause the sub-bandgap absorption are removed from the Si matrix to form Te-related complexes, which are electrically and optically inactive. In this work, we explore the formation of defects in Te-hyperdoped Si layers which leads to the electrical deactivation upon furnace annealing through the analysis of optical and microstructural properties as well as positron annihilation lifetime spectroscopy. Particularly, Te-rich clusters are observed in samples thermally annealed at temperature reaching 950 °C and above. Combined with polarized Raman analysis and transmission electron microscopy, the observed crystalline clusters are suggested to be Si2Te3.

Sn-V centers in diamond activated by ultra high pressure and high temperature treatment

We investigate the activation of Sn-V centers in diamond through ions implantation and the subsequent high pressure and high temperature (HPHT) treatment at 15 GPa and 2300 °C. Sn ions is implanted at fluences greater than 2 × 1014 cm−2 by varying the acceleration voltage up to 180 kV, which results in a Sn distribution with a uniform concentration of 1 × 1020 cm−3 down to a depth of 50 nm from the surface. The subsequent HPHT treatment recovers the transparent appearance and preserves the introduced Sn ions. The sample shows emission peaks composed of four levels that originate from the Sn-V centers. The two distinct emission peaks from the lower excited states to the split ground states are stable up to 77 K. At 10 K, these peaks are clearly observable at excitation powers spanning two orders of magnitude, which suggests the preferential carrier capture at these centers.

Electrostatic self-assembly design of core@shell structured Al2O3@C nanospheres towards high-efficiency and damage-free polishing sapphire wafer

A novel core@shell structured nanocomposite particles with carbon as soft shell and nanoAl2O3 as hard core were prepared by electrostatic self-assembly, and the subsequent hydrothermal and high temperature treatment. By adjusting concentration of nanoAl2O3, the average size of the composite particles vary from 750 nm to 150 nm, the corresponding to the thickness of the carbon shell in the range of 355–55 nm. On the basic of the TEM and Raman results, the shell materials were composed of the amorphous carbon. As confirmed by XPS, the Al2O3 @C composite particles had a stable structure, owing to the formation of the interfacial bonding between carbon shell and nanoAl2O3 after the carbonization process. Moreover, the nanoAl2O3 @carbon composite abrasive could lead to a decrease in the surface damage and roughness of the sapphire wafer compared with the nanoalumina abrasive, owing to the elastic effect coming from the amorphous carbon shell.

Chemical Vapor Deposition of an Iridium Phase on Hafnium Carbide and Tantalum Carbide

Nanocrystalline iridium coatings on hafnium carbide and tantalum carbide substrates are prepared by chemical vapor deposition (MOCVD) at 600°С. Subsequent high-temperature treatment at 1100°С gives rise to chemical reactions between iridium and hafnium carbide or tantalum carbide to yield nanosized substitutional intermetallic solid solutions MIr3 – x and evolve free carbon. The occurrence of intermetallic interaction is proved by X-ray photoelectron (XPS) spectroscopy.