Self-propagating High-temperature Synthesis Research Articles

Wear and corrosion resistance of Al2O3 and TiC deposition on steel substrate using Self- propagating High temperature Synthesis method

Abstract In the present work, a low-carbon steel substrate was coated with Al2O3 and TiC using self-propagating high temperature synthesis. The synthesized coatings were annealed at 450oC for 2-6 hrs. The characteristics of the substrate, coated, and annealed samples were examined, including microhardness, wear resistance, and corrosion resistance. A pin-on-disc tribometer was employed to conduct the wear test by varying the load, sliding velocity, and distance. The impact of these factors on the wear rate and worn surface morphology was then examined. Further, corrosion resistance was evaluated using electrochemical corrosion testing with 3.5 wt.% NaCl as electrolyte. Results showed that Al2O3 and TiC specimens annealed at 450oC for 5 hrs and 4 hrs improved the microhardness by 1.3 and 1.06 times than that of as-coated specimens respectively. The synthesized Al2O3 and TiC coatings showed an abrasive wear mechanism at higher loads and tribolayer formation was observed at higher sliding velocity and distances. The corrosion and wear resistances of the samples were found as follows: substrate< Al2O3 coated < TiC coated < Al2O3 annealed < TiC annealed. The Al2O3 and TiC ceramic coatings were found to improve wear and corrosion resistance having potential applications in cement, petrochemical, and marine industries.

Self-Propagating High-Temperature Synthesis of Composite Material Based on Stabilized Zirconium Oxide1

Self-Propagating High-Temperature Synthesis of Composite Material Based on Stabilized Zirconium Oxide1

Effect of SHS powder processing on structure formation and optical transmittance of MgO–Y2O3 composite ceramic

Extending the transparency range of MgO–Y2O3 composite ceramic to wavelength less than 3 μm is highly desirable, as it broadens their potential applications in infrared (IR) optics. This study illustrates the effectiveness of deagglomerating a mixture of magnesium oxide and yttrium sesquioxide powders, derived from self-propagating high-temperature synthesis (SHS), in achieving this goal. The impact of powder deagglomeration on the microstructure and porosity defects of hot-pressed MgO–Y2O3 ceramic was analyzed using electron and IR microscopy. The results showed that the deagglomeration enhanced the homogeneity of the composite grain mixture, slowed down the grain growth, suppressed the formation of large grains, and significantly reduced the number of porosity microdefects in the material. The optical transmittance increased from 42 % to 77 % at a wavelength of 2 μm (for samples with a thickness of 1.2 mm) when deagglomerated powders were used, compared to non-deagglomerated ones.

Liquid metal assistant self-propagating high-temperature synthesis of S-containing high-entropy MAX-phase materials

Liquid metal assistant self-propagating high-temperature synthesis of S-containing high-entropy MAX-phase materials

Nano- and Submicron-Sized TiB2 Particles in Al–TiB2 Composite Produced in Semi-Industrial Self-Propagating High-Temperature Synthesis Conditions

Nano- and Submicron-Sized TiB2 Particles in Al–TiB2 Composite Produced in Semi-Industrial Self-Propagating High-Temperature Synthesis Conditions

Enhanced oxidation resistance of ZrB2-MoSi2 coating through MoSi2-TaSi2 double-silicide alloying modifying

This study explored how MoSi2-TaSi2 ratios in silicide alloys influence the oxygen resistance of ZrB2-MoSi2-TaSi2 coatings, using self-propagating high-temperature synthesis and spark plasma sintering. The oxidative self-separation effect of TaSi2 and MoSi2 enhances nanoscale Zr and Ta oxide particle dispersion, forming a Zr-B-Ta-Si-O glass with optimal oxygen-blocking in the 50ZrB2-(MoSi2-10TaSi2) coating (ZMT10). Compared to ZrB2-MoSi2, ZMT10 showed 28.87 % and 48.21 % reductions in weight gain and oxygen penetration, increasing protection to 99.71 %. Excessive TaSi2 leads to Ta5+ dissolution, oxide aggregation, and a dendritic structure, facilitating oxygen diffusion and oxidation, raising the oxygen penetration in 50ZrB2-(MoSi2-30TaSi2) to 0.73 %, lowering protection to 99.18 %.

Preparation of a hard AlTiVCr compositionally complex alloy by self-propagating high-temperature synthesis

In this study, an AlTiVCr compositionally complex alloy with a high hardness of 865 ± 34 HV was prepared by a one-step self-propagating high-temperature synthesis (SHS) method using TiO2, V2O5, Cr2O3, and Al as starting materials. Experimental results confirmed the formation of a two-phase alloy having BCC solid solution dendritic grains reinforced by a Ti-rich intermetallic phase. Elemental analysis results confirmed that the Ti at.% in the synthesized alloy was lower than other elements. The addition of extra TiO2 to the reactants, pre-milling of the TiO2-Al mixture, and using the Rutile polymorph of TiO2 instead of Anatase as the starting material increased the atomic percent of Ti. The composition of the proper synthesized alloy was formulated as Al27.3Ti17.2V28.7Cr26.8 which is close to the desired AlTiVCr alloy. To clarify the reaction sequence during the SHS, the binary mixtures were analyzed by thermal analysis. It was postulated that the melting of Al facilitated the reduction reaction of Cr2O3 and VxOy compounds, while TiO2 was the last oxide compound reduced by Al. This hindered the completion of the TiO2 reduction reaction and as a consequence, the unreacted TiO2 entered the slag which lowered the concentration of Ti in the composition of the final alloy.

Antibacterial activity and biocompatibility of titanium nickelide augments with the addition of silver nanoparticles for bone grafting: an experimental study

BACKGROUND: The relevance of this study was supported by the increasing number of infectious complications of bone augmentation in children and adults. Currently, porous titanium nickelide alloys are among the most preferred materials used in bone plasty. Despite the observable advantages of porous nickelide titanium alloys in terms of biochemical and biomechanical compatibility with the body, research on the antibacterial activity of alloys is ongoing to counter the development of infections at the implant–biological tissue border.
 AIM: To perform an experimental study of the biocompatible antibacterial surface in porous titanium nickelide alloys with the addition of silver nanoparticles.
 MATERIALS AND METHODS: Titanium nickelide alloys with 62% porosity were obtained using the self-propagating high-temperature synthesis method from nickel, titanium, and nanosilver powders at concentrations of 0.2 at.% Ag, 0.5 at.% Ag, and 1.0 at.% Ag, respectively. The experiment was conducted on nine sexually mature female white laboratory rats. They were divided into three groups, with three rats each. All animals were implanted with titanium nickelide along with porous granules of silver additives. The first group was the control, the second received 0.2 at.% silver, and the third received 0.5% silver. The standard method of incubating Staphylococcus epidermidis in liquid broth in the presence of the studied images was used to determine bactericidal activity, followed by seeding on solid media and counting colonies.
 RESULTS: The antibacterial effect of the samples on S. epidermidis gradually increased with increasing silver concentration. The significance of the differences between the experiment and control was confirmed by Student’s criterion p 0.005, whereas the sample without silver nanoparticles and the control do not differ significantly. Thus, these alloys may have bioactive properties because they contain silver nanoparticles. An alloy with a silver concentration of 0.5 at.% Ag showed the best antibacterial activity to S. epidermidis. In the clinical evaluation of the results of the experimental study, purulent inflammatory complications were not observed in all animals at all times. On day 75, the animals underwent computed tomography, which showed good occupancy of the bone defect and absence of a dystrophic effect on the area where the bone and soft tissue are in contact with the material.
 CONCLUSIONS: If the concentration of silver nanoparticles is increased up to 0.5 at%, the antibacterial activity and cytocompatibility of the implant also increase. Clinical experimental evaluation in all groups of animals showed that osteointegration of alloys with 0.5 at.% Ag begins immediately after implantation and is completed 2 weeks earlier than that in the remaining groups.

Self-propagating high-temperature synthesis of AlxCoCrFeNiMoy high-entropy alloys: thermochemical modelling, microstructural evaluation and high temperature oxidation behaviour

In this study, the feasibility of the synthesis of AlxCoCrFeNiMoy (0.5 < x < 3, y = 0.5,1) alloys via cost and energy efficient thermochemical modelling assisted (FactSage™) aluminothermic self-propagating high-temperature synthesis (SHS) method was investigated. In addition, selected SHS alloys were also suction-casted into a bar shape by using a vacuum arc melter and the microstructural changes and oxidation behaviour of selected alloys were investigated. The characterization results demonstrated that AlxCoCrFeNiMoy (0.5 < x < 3, y = 0.5,1) master alloys can be successfully synthesized via thermochemical modelling assisted SHS method with a substantial composition control. The microstructures of the SHS alloys were found to comprise of the FCC-A1, BCC (A2, B2) and σ phases with varying fractions depending on the composition. Increasing Al content was found to increase the hardness of the alloys from 278 HV to 829 HV for the AlxCoCrFeNiMo0.5 system. For AlxCoCrFeNiMo system, on the other hand, it had an increasing effect from Al0.5 to Al1.0 (from 659 HV to 903 HV) initially and then decreased the hardness to the levels of 773 HV with the further addition of Al. Suction-cast alloys exhibited rather similar microstructures with similar phase constituents and hardness values. As a general trend primer B2 phase fraction was increased due to higher cooling rate. Oxidation studies revealed that the Al3.0Mo0.5 alloy, which has higher B2 content (919 HV), exhibited better oxidation resistance after 100 h of exposure to air at 800 °C. Postulated scaling mechanisms, supported with the CALPHAD simulations and Raman analyses, revealed the formation of non-protective spinel oxides and sublimation of volatile MoOx oxides before the stabilization of a protective M2O3 (M = Al,Cr) layer, especially for the AlCoCrFeNiMo alloy.

A Review of the State of Art of Fabrication Technologies of Titanium Aluminide (Ti-Al) Based on US Patents

This article evaluates the fabrication technologies of titanium aluminide (Ti-Al) and its practical applications by comparing it with the well-known Ti-Al binary phase diagram and US patents. Meanwhile, by analyzing and discussing the various patented Ti-Al fabrication technologies and applications, this article discusses the applications of Ti-Al-based alloys, mainly in the aircraft field. The improved fabrication processes and new application technologies are under patent protection. These technologies are classified into six categories: basic research on Ti-Al-based alloys, powder metallurgy of Ti-Al-based alloys, casting and melting of Ti-Al-based alloys, PM and AM manufacturing methods for aircraft applications, other fabrication technologies by Ti-Al-based alloys, and self-propagating high-temperature synthesis (SHS) of Ti-Al-based alloys. By comparing the principles and characteristics of the above techniques, the advantages, disadvantages, and application fields of each are analyzed and their developments are discussed. Based on the characteristics of Ti-Al, new fabrication and application technologies can be developed, which can overcome the existing disadvantages and be used to form new aircraft components.

Sorption of Radium-226 on Few-Layer Graphene Synthesized under Conditions of Self-Propagating High-Temperature Synthesis

Sorption of Radium-226 on Few-Layer Graphene Synthesized under Conditions of Self-Propagating High-Temperature Synthesis

Structural characteristics and properties of heat-resistant nickel β-alloys produced via the centrifugal SHS-casting method

Employing centrifugal self-propagating high-temperature synthesis (SHS) metallurgy, complemented by advanced metallurgical processes such as vacuum induction melting (VIM) and vacuum arc remelting (VAR), yielded the alloy formulation denoted as base–2.5Mo–1.5Re–1.5Ta–0.2Ti. This study investigates the effects of various technological modes and additional metallurgical treatments on the alloy's impurity and non-metallic inclusion content, structural characteristics, mechanical behavior under compression, and its oxidation mechanisms and kinetics when exposed to temperatures of 1150 °C for 30 h. With increasing centrifugal acceleration, the proportion of non-metallic inclusions (number of points) drops from 5 to 1–2 points. The best combination mechanical properties, including σucs = 1640 ± 20 MPa, σys = 1518 ± 10 MPa, and residual deformation were observed in alloys processed under conditions of increased gravitational force (g = 50). Within a centrifugal force range of g = 20÷300, the composition of the synthesis products aligned with the theoretical expectations. The total content of impurities is 0.15 ± 0.02 %, with a decrease in gas impurities–oxygen and nitrogen levels reduced to 0.018 % and 0.0011 %, respectively. The structural analysis of the alloys revealed the presence of globular and streaked inclusions of a chromium-based solid solution embedded within the matrix. Inclusions with thickness of 2–8 μm are present in the intergranular space: (Cr)Ni,Mo,Co, (Cr)Mo,Re and (Cr)Re,Mo. The formation of the Ni(Al,Ti) phase at grain boundaries was identified, contributing to an enhancement in plastic resistance and overall strength of the alloy. Oxidation mechanisms varied across different processing modes, with the size of structural components significantly influencing oxidation kinetics. The weight gain observed in SHS samples was 70 ± 10 g/m2 with oxidation predominantly occurring along the NiAl interphase boundaries and penetrating into the depth of the sample. TEM facilitated the identification of phases enriched with Ti microadditions, reducing the levels of dissolved nitrogen and oxygen within the intermetallic phase to a combined weight percentage (ΣO,N) of 0.0223 wt.%.

Determination of nitrogen in titanium, aluminum, silicon, hafnium nitrides and compositions on their base using a Metavak-AK analyzer

Methods for determining nitrogen in the products of self-propagating high-temperature synthesis (SHS), i.e., titanium, aluminum, silicon, and hafnium nitrides using a Metavak-AK gas analyzer have been developed. The optimal modes of analysis have been selected: the time and temperature of degassing of the crucible with flux in the furnace, the time and temperature of purging the extraction chamber with the sample, the time of automatic dumping of the sample from the loading chamber into the crucible, the time and temperature of purging the chamber after loading, the time of removal of gaseous products of reduction melting and registration of nitrogen signals. Furnace operating programs were compiled to determine the nitrogen content in TiN, AlN, Si3N4, HfN. Reduction melting of the samples took place in a helium flow at a furnace temperature of 2700°C for TiN, AlN, HfN, and 2500°C for Si3N4. To speed up the process and complete nitrogen extraction, a metal bath was used: nickel grit in the case of titanium and hafnium nitrides, and combined Sn/Ni flux for aluminum and silicon nitrides. The nitrogen content in the studied samples was determined in the range from 0.12 up to 39.3 %wt., the relative standard deviation was 0.6 – 3.6%. The accuracy of the results obtained on a Metavak-AK gas analyzer is confirmed by the Kjeldahl and Dumas reference methods.

Using the Spark Plasma Sintering System for Fabrication of Advanced Semiconductor Materials.

The interest in the Spark Plasma Sintering (SPS) technique has continuously increased over the last few years. This article shows the possibility of the development of an SPS device used for material processing and synthesis in both scientific and industrial applications and aims to present manufacturing methods and the versatility of an SPS device, presenting examples of processing Arc-Melted- (half-Heusler, cobalt triantimonide) and Self-propagating High-temperature Synthesis (SHS)-synthesized semiconductor (bismuth telluride) materials. The SPS system functionality development is presented, the purpose of which was to broaden the knowledge of the nature of SPS processes. This approach enabled the precise design of material sintering processes and also contributed to increasing the repeatability and accuracy of sintering conditions.

Refinement of the Manufacturing Route and Evaluation of the Reinforcement Effect of MAX Phases in Al Alloy Matrix Composite Materials

Microwave Assisted Self-propagating High-temperature Synthesis (MASHS) was used to prepare open-porous MAX phase preforms in Ti-Al-C and Ti-Si-C systems, which were further used as reinforcements for Al-Si matrix composite materials. The pretreatment of substrates was investigated to obtain open-porous cellular structures. Squeeze casting infiltration was chosen to be implemented as a method of composites manufacturing. Process parameters were adjusted in order to avoid oxidation during infiltration and to ensure the proper filling. Obtained materials were reproducible, well saturated and dense, without significant residual porosity or undesired interactions between the constituents. Based on this and the previous work of the authors, the reinforcement effect was characterized and compared for both systems. For the Al-Si+Ti-Al-C composite, an approx. 4-fold increase in hardness and instrumental Young's modulus was observed in relation to the matrix material. Compared to the matrix, Al-Si+Ti-Si-C composite improved more than 5-fold in hardness and almost 6-fold in Young's modulus. Wear resistance (established for different loads: 0.1, 0.2 and 0.5 MPa) for Al-Si+Ti-Al-C was two times higher than for the sole matrix, while for Al-Si+Ti-Si-C the improvement was up to 32%. Both composite materials exhibited approximately two times lower thermal expansion coefficients than the matrix, resulting in enhanced dimensional stability.

Boosting Thermoelectric Performance via Weakening Carrier-Phonon Coupling in BiCuSeO-Graphene Composites.

BiCuSeO is a promising oxygen-containing thermoelectric material due to its intrinsically low lattice thermal conductivity and excellent service stability. However, the low electrical conductivity limits its thermoelectric performance. Aliovalent element doping can significantly improve their carrier concentration, but it may also impact carrier mobility and thermal transport properties. Considering the influence of graphene on carrier-phonon decoupling, Bi0.88 Pb0.06 Ca0.06 CuSeO (BPCCSO)-graphene composites are designed. For further practical application, a rapid preparation method is employed, taking less than 1h, which combines self-propagating high-temperature synthesis with spark plasma sintering. The incorporation of graphene simultaneously optimizes the electrical properties and thermal conductivity, yielding a high ratio of weighted mobility to lattice thermal conductivity (144 at 300K and 95 at 923K). Ultimately, BPCCSO-graphene composites achieve exceptional thermoelectric performance with a ZT value of 1.6 at 923K, bringing a ≈40% improvement over BPCCSO without graphene. This work further promotes the practical application of BiCuSeO-based materials and this facile and effective strategy can also be extended to other thermoelectric systems.

Porosity and phase composition effects on SHS-NiTi structure and mechanical properties

NiTi samples with 59–70% porosity were obtained by the self-propagating high-temperature synthesis (SHS) using Ti, Ni, and NiTi powders as inert. The maximum and average pore sizes increase, while the maximum and average dimensions of the bridges decrease with porosity, controlled by adjusting the amount of inert additives, based on the surface and cross-sectional microscopy studies. The phase composition of porous NiTi was determined by X-ray diffraction. The alloy contains an austenitic B2 TiNi phase, a martensitic B19′ TiNi phase, and a secondary Ti2Ni phase. SHS-NiTi samples with different porosity were tested by uniaxial compression, revealing mechanical properties’ dependence on porosity. It is shown that with an 11% increase in the NiTi alloy porosity, the yield and compressive strength are reduced by almost a factor of 2.

Self-Propagating High-Temperature Synthesis of Complex Phases: The Example of TiC-Based Composites

Self-Propagating High-Temperature Synthesis of Complex Phases: The Example of TiC-Based Composites

Ultra-high-performance graphene-based bulk materials strengthened by Y-type connection structure

The strategic design and assembly of bulk graphene materials represent a pivotal advancement for harnessing the inherent properties of graphene in practical applications. However, fabricating high-strength graphene-based bulk materials from graphene powders presents a significant challenge, primarily due to interlayer slippage between the graphene layers. Here, a unique Y-type connection structure was found in few-layer graphene synthesized by self-propagating high-temperature synthesis (SHS) and subsequently retained in graphene-based bulk materials prepared by spark plasma sintering (SPS) process. The Y-type connection structure and defect-induced linkages serve to cross-link the graphene-based bulk materials. Consequently, the bulk material exhibited an ultra-high compressive strength, reaching 2.14 GPa, supported by Molecular dynamics (MD) simulations which demonstrated that the Y-type connection structure increases the shear modulus and the load transfer rate. The Y-type connection structure plays a vital role in reinforcing the strength of graphene-based bulk materials, offering valuable insights for the microstructural design and property augmentation of other graphene-derived materials. Besides it’s ultra-high compressive strength, the graphene-based bulk material also performs a low thermal expansion coefficient (0.5 × 10−6 K−1), high electrical conductivity (1.47 × 105 S·m−1) and exceptional EMI shielding capability.

In Situ Formation of Titanium Diboride/Magnesium Titanate Composites by Magnesiothermic-Based Combustion Synthesis

In situ formation of TiB2–Mg2TiO4 composites was investigated by combustion synthesis involving the solid-state reaction of Ti with boron and magnesiothermic reduction of B2O3. Certain amounts of MgO and TiO2 were added to the reactant mixtures of Ti/B/Mg/B2O3 to act as the moderator of highly exothermic combustion and a portion of the precursors to form Mg2TiO4. Two combustion systems were designed to ensure that synthesis reactions were sufficiently energetic to carry on self-sustainably, that is, in the mode of self-propagating high-temperature synthesis (SHS). Consistent with thermodynamic analyses, experimental results indicated that the increase in pre-added MgO and TiO2 decreased the combustion temperature and propagation velocity of the flame front. MgO was shown to have a stronger dilution effect on combustion exothermicity than TiO2, because the extent of magnesiothermic reduction of B2O3 was reduced in the MgO-added samples. In situ formation of the TiB2–Mg2TiO4 composite was achieved from both types of samples. It is believed that, in the course of the SHS progression, Mg2TiO4 was produced through a combination reaction between MgO and TiO2, both of which were entirely or partially generated from the metallothermic reduction of B2O3. The microstructure of the products exhibited fine TiB2 crystals in the shape of short rods and thin platelets that existed within the gaps of Mg2AlO4 grains. Both constituent phases were well distributed. A novel and efficient synthesis route, which is energy- and time-saving, for producing Mg2TiO4-containing composites was demonstrated.