Search Results (32)

Developing advanced nuclear fuel technologies is critical for high-performance applications such as nuclear thermal propulsion (NTP). This study explores the feasibility of direct ink writing (DIW) for fabricating ceramic pellets for potential nuclear applications. Zirconium carbide (ZrC) is used as a matrix material and vanadium carbide (VC) is used as a surrogate for uranium carbide (UC) in this study. A series of ink formulations were developed with varying concentrations of VC and nanocrystalline cellulose (NCC) to optimize the rheological properties for DIW processing. Post-sintering analysis revealed that conventionally sintered samples at 1750 °C exhibited high porosity (>60%), significantly reducing the compressive strength compared to dense ZrC ceramics. However, increasing VC content improved densification and mechanical properties, albeit at the cost of increased shrinkage and ink flow challenges. Spark plasma sintering (SPS) achieved near-theoretical density (~97%) but introduced geometric distortions and microcracking. Despite these challenges, this study demonstrates that DIW offers a viable route for fabricating ZrC-based ceramic structures, provided that sintering strategies and ink rheology are further optimized. These findings establish a baseline for DIW of ZrC-based materials and offer valuable insights into the porosity control, mechanical stability, and processing limitations of DIW for future nuclear fuel applications. Full article

To elucidate the key material parameters governing the tribological performance of ceramic composites under dry sliding against steel, this study presents a comprehensive comparative assessment of the microstructural characteristics, mechanical performance, and tribological behavior of two alumina–zirconia (Al₂O₃–ZrO₂) ceramic composites, each reinforced with a 42 vol.% carbide phase: zirconium carbide (ZrC) and tungsten carbide (WC). Specifically, tungsten carbide (WC) was selected for its exceptional bulk mechanical properties, while zirconium carbide (ZrC) was chosen to contrast its potentially different interfacial reactivity against a steel counterface. ZrC and WC were selected as reinforcing phases due to their high hardness and distinct chemical and interfacial properties, which were expected to critically affect the wear and friction behavior of the composites under demanding conditions. Specimens were consolidated via spark plasma sintering (SPS). The investigation encompassed macro- and nanoscale hardness measurements (Vickers hardness HV₁, HV₁₀; nanoindentation hardness H), elastic modulus (E), fracture toughness (K_IC), coefficient of friction (COF), and specific wear rate (W_s) under unlubricated reciprocating sliding against 100Cr6 steel at normal loads of 10 N and 25 N. The Al₂O₃–ZrO₂–WC composite exhibited an ultrafine-grained microstructure and markedly enhanced mechanical properties (HV₁₀ ≈ 20.9 GPa; H ≈ 33.6 GPa; K_IC ≈ 4.7 MPa·m^½) relative to the coarse-grained Al₂O₃–ZrO₂–ZrC counterpart (HV₁₀ ≈ 16.6 GPa; H ≈ 27.0 GPa; K_IC ≈ 3.2 MPa·m^½). Paradoxically, the ZrC-reinforced composite demonstrated superior tribological performance, with a low and load-independent specific wear rate (W_s ≈ 1.2 × 10⁻⁹ mm³/Nm) and a stable steady-state COF of approximately 0.46. Conversely, the WC-reinforced system exhibited significantly elevated wear volumes—particularly under the 25 N regime—and a higher, more fluctuating COF. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX) of the wear tracks revealed the formation of a continuous, iron-enriched tribofilm on the ZrC composite, derived from counterface material transfer, whereas the WC composite surface displayed only sparse tribofilm development. These findings underscore that, in steel-paired tribological applications of Al₂O₃–ZrO₂–based composites, the efficacy of interfacial tribolayer generation can supersede intrinsic bulk mechanical attributes as the dominant factor governing wear resistance. Full article

The chemical and microstructural transformation of the surface of a 31.5 vol.% ZrB₂-31.5 vol.% HfB₂-27 vol.% SiC-10 vol.% C_CNT ultrahigh-temperature ceramic sample (where C_CNT refers to carbon nanotubes) was studied under the influence of a subsonic N₂-plasma flow with the addition of 5 mol% methane, simulating aerodynamic heating in the atmosphere of Titan. As in the case of pure nitrogen flow, it was found that silicon carbide is removed from the surface. Zirconium and hafnium diborides are partially transformed into a Zr-Hf-B-C-N solid solution in the experiment conducted. XRD, Raman spectroscopy, and SEM-EDX analysis show that the presence of C₂ in the N₂-CH₄ plasma flow leads to surface carbonization (formation of a graphite- and diamond-like coating with a high proportion of amorphous carbon), resulting in significant changes in the microstructure and emissivity, potentially affecting the catalytic properties of the surface. Full article

There has been growing interest and increasing attention in the field of functional clothing textiles, particularly in product and process development, as well as innovations in heat-generating, retaining, and releasing fibers to maintain a healthy body temperature without relying on unsustainable energy sources. This study, for the first time, reports the various physio-mechanical properties of surface-functionalized regenerated cellulose fibers (RCFs) coated with ceramic particles. The coating imparts photothermal conversion-based heat generation and retention properties with the aid of polyelectrolyte binders. In this design, ZrC enables the conversion of light energy into thermal energy, providing heat for the human body. A feasible coating process was employed, utilizing industrially feasible exhaustion methods to deposit the ZrC particles onto the RCF surface in conjunction with two distinctive polymeric binders, specifically polyethyleneimine (PEI) and polydiallyldimethylammonium chloride (polyDADMAC). The morphological characteristics and tensile properties of the coated RCFs were analyzed via scanning electron microscopy (SEM) and single-fiber tensile testing. Heat retention and release behaviors of a bundle of fiber samples were assessed using infrared (IR) imaging and an IR emission lamp setup. The SEM results confirmed the successful coating of the ZrC particles on the surface of the RCF samples, influencing negligible on their physical–mechanical properties. The heat retention of the coated RCFs with ZrC and both binders was higher than that of reference regenerated cellulose fibers (RCFs), demonstrating their effective heat generation, retention, and heat release properties. Based on the highlighted prominent results for the coated RCFs, these findings highlight the suitability of the developed functional clothing textiles for targeted applications in non-extreme thermal conditions, ensuring thermo-physiological comfort by maintaining body temperature within a tolerable thermal range (36.5–37.5 °C), in contrast to studies reporting significantly higher temperatures (50–78 °C) for extreme thermal conditions. Full article

Research into the introduction of alloying and reinforcing nanocomposites into nickel (Ni) coatings has been motivated by the need for tribologically superior coatings that will improve energy efficiency. Using pulse electrodeposition, this work investigates the effects of adding cobalt (Co) as the alloying nanoparticle and silicon carbide (SiC), zirconium oxide (ZrO₂), and aluminium oxide (Al₂O₃) as reinforcing nanocomposites to Ni coatings. The surface properties, mechanical strength, nanotribological behaviour, and wettability of these coatings were analysed. Surface characteristics were evaluated by the use of a Scanning Electron Microscope, revealing a grain dimension reduction of approximately ~7–43% compared to pristine Ni coatings. When alloying and reinforcing nanocomposites were added to Ni coatings, nanoindentation research showed that there was an increase in nanohardness of ~12% to ~69%. This resulted in an improvement in the tribological performance from approximately 2% to 65%.The hydrophilic nature of Ni coatings was observed with wettability analysis. This study demonstrates that nanocomposite reinforcement can be used to customise Ni coatings for applications that require exceptional tribological performance. The results point to the use of Ni-Co coatings for electronics and aerospace sectors, with more improvements possible with the addition of reinforcing nanoparticles. Full article

When combined with ceramics, ternary carbides, nitrides, and borides form a class of materials known as MAX phases. These materials exhibit a multilayer hexagonal structure and are very strong, damage tolerant, and thermally stable. Further, they have a low thermal expansion and exhibit outstanding resistance to corrosion and oxidation. However, despite the numerous MAX phases that have been identified, the search for better MAX phases is ongoing, including the recently discovered Zr₃InC₂ and Hf₃InC₂. The properties of MAX phases are still being tailored in order to lower their ductility. This study investigated Ti₃AlC₂ alloyed with nitrogen, gallium, hafnium, and zirconium with the aim of achieving better mechanical and thermal performances. Density functional theory within Quantum Espresso module was used in the computations. The Perdew–Burke–Ernzerhof generalised gradient approximation functionals were utilised. (ZrHf)₄AlN₃ exhibited an enhanced bulk and Young’s moduli, entropy, specific heat, and melting temperature. The best thermal conductivity was observed in the case of (ZrHf)₃AlC₂. Further, Ti₃AlC₂ exhibited the highest shear modulus, Debye temperature, and electrical conductivity. These samples can thus form part of the group of MAX phases that are used in areas wherein the above properties are crucial. These include structural components in aerospace and automotive engineering applications, turbine blades, and heat exchanges. However, the samples need to be synthesised and their properties require verification. Full article

In this study, a single zirconium carbide (ZrC) nanoneedle structure oriented in the <100> direction was fabricated by a dual-beam focused ion beam (FIB-SEM) system, and its field emission characteristics and emission current stability were evaluated. Benefiting from controlled fabrication with real-time observation, the ZrC nanoneedle has a smooth surface and a tip with a radius of curvature smaller than 20 nm and a length greater than 2 μm. Due to its low work function and well-controlled morphology, the ZrC nanoneedle emitter, positioned in a high-vacuum chamber, was able to generate a single and collimated electron beam with a current of 1.2 nA at a turn-on voltage of 210 V, and the current increased to 100 nA when the applied voltage reached 325 V. After the treatment of the nanoneedle tip, the field emission exhibited a stable emission for 150 min with a fluctuation of 1.4% and an emission current density as high as 1.4 × 10¹⁰ A m⁻². This work presents an efficient and controllable method for fabricating nanostructures, and this method is applicable to the transition metal compound ZrC as a field emission emitter, demonstrating its potential as an electron source for electron-beam devices. Full article

The <100> oriented single-crystalline Zirconium Carbide (ZrC) nanowires were controllably synthesized on a graphite substrate by chemical vapor deposition (CVD) with optimized growth parameters involving Zirconium tetrachloride (ZrCl₄), flow of methane (CH₄), and growth temperature. The length of nanowires is above 10 µm while the diameter is smaller than 100 nm. A single ZrC nanowire was picked up and fixed on a tungsten tip for field emission measurement. After surface pretreatments, a sharpened and cleaned ZrC nanowire emitter showed a high emission current density of 1.1 × 10¹⁰ A m⁻² at a low turn-on voltage of 440 V. The field emission is stable for 150 min with a fluctuation of 1.77%. This work provides an effective method for synthesizing and stabilizing single-crystalline ZrC nanowire emitters as an electron source for electron-beam applications. Full article

Zirconium carbide (ZrC) ceramics have a high melting point, low neutron absorption cross section, and excellent resistance to the impact of fission products and are considered to be one of the best candidate materials for fourth-generation nuclear energy systems. ZrC ceramics with a high relative density of 99.1% were successfully prepared via pressureless sintering using a small amount of MoSi₂ as an additive. The influence of the MoSi₂ content on the densification behavior, microstructure, mechanical properties, and thermal properties of ZrC ceramics was systematically investigated. The results show that the densification of ZrC was significantly enhanced by the introduction of MoSi₂ due to the formation of a liquid phase during sintering. In addition, the ZrC grains were refined due to the pinning effect of the generated silicon carbide. The flexural strength and Vickers hardness of ZrC ceramics with 2.5 vol% MoSi₂ sintered at 1850 °C were 408 ± 12 MPa and 17.1 GPa, respectively, which were approximately 30% and 10% higher compared to the samples without the addition of MoSi₂. The improved mechanical properties were mainly attributed to the high relative density (99.1%) and refined microstructure. Full article

Trace elements such as boron (B) and zirconium (Zr) can increase creep resistance in nickel-based superalloys. This study investigates the change of microstructures on the grain boundary (GB) in phase-controlled nickel-based superalloys through the addition of trace elements. The basis alloy without B and Zr has distributed micrometer-sized (Nb, Ti)C and Cr₂₃C₆ carbides at the GBs. Zr is detected alongside Nb and Ti within certain (Nb, Ti)C carbides and its addition increases the fraction of (Nb, Ti)C or (Nb, Ti, Zr)C carbides. B affects the formation of precipitates constructed by nanometer-sized precipitates, which are Cr₂₃C₆ carbides, Cr₂₃(C, B)₆ boro-carbides, and Cr-rich borides, surrounded by γ’ phases. This film structure, which includes nanometer-sized precipitates surrounded by γ’ phases, forms more continuously with the addition of B and Zr. It is constructed with precipitates of (Nb, Ti)C carbides and Cr₂₃(C, B)₆ boro-carbides surrounded by γ’ phases. Numerous nanometer-sized precipitates (i.e., (Nb, Ti)C and Cr₂₃(C, B)₆) are distributed alternately within the film structure. The effect of the addition of B and Zr is such that nucleation sites of each precipitate are formed simultaneously and alternately along the GBs. The experimental results were discussed by correlating them with the predicted fraction of stable phases depending on the temperatures of these alloys, using the JMatPro program. Full article

Thermal wear comfort for workwear clothing plays a vital role in maintaining comfortable water- and moisture-vapor-permeable properties while wearing clothing. In particular, thermal wear comfort measured using a thermal manikin is required in the protective workwear clothing market because their use provides objective data concerning the actual wearing performance of the clothing. This paper investigated the thermal wear comfort properties of various ceramic-embedded composite fabrics for workwear clothing worn in gas and oil industries produced from new schemes. The thermal insulation rate (Clo value) of Al₂O₃(Aluminum oxide)/graphite, ZnO(zinc oxide)/ZrC(zirconium carbide) and ZnO/ATO(antimony tin oxide)-embedded clothing was greater (25.5, 24.7 and 16.9%, respectively) than that of regular clothing (control), which was in accordance with the results (15.0, 13.8 and 11.3% higher, respectively) of the heat retention rate (I) of fabric specimens. It revealed that ZnO- and ATO-embedded yarns mixed with ZrC particles enhanced thermal wear comfort and had superior anti-static and UV-protective properties. Considering UV-protective and anti-static protective clothing worn in gas and oil industries and cold weather regions, it can be concluded that ZnO/ZrC-incorporated fabric is suitable because it showed superior thermal wear comfort with excellent UV-protective and acceptable anti-static properties. Meanwhile, assuming high functional performance for protective clothing worn in winter and factories, ZnO/ATO-incorporated fabric is pertinent to fabricating protective clothing for cold weather regions. Full article

At ultra-high temperatures, resilient, durable, stable material choices are limited. While Carbon/Carbon (C/C) composites (carbon fibers and carbon matrix phases) are currently the materials of choice, zirconium carbide (ZrC) provides an option in hypersonic environments and specifically in wing leading edge (WLE) applications. ZrC also offers an ultra-high melting point (3825 K), robust mechanical properties, better thermal conductivity, and potentially better chemical stability and oxidation resistance than C/C composites. In this review, we discuss the mechanisms behind ZrC mechanical, thermal, and chemical properties and evaluate: (a) mechanical properties: flexure strength, fracture toughness, and elastic modulus; (b) thermal properties: coefficient of thermal expansion (CTE), thermal conductivity, and melting temperature; (c) chemical properties: thermodynamic stability and reaction kinetics of oxidation. For WLE applications, ZrC physical properties require further improvements. We note that materials or processing solutions to increase its relative density through sintering aids can have deleterious effects on oxidation resistance. Therefore, improvements of key ZrC properties for WLE applications must not compromise other functional properties. We suggest that C/C-ZrC composites offer an engineering solution to reduce density (weight) for aerospace applications, improve fracture toughness and the mechanical response, while addressing chemical stability and stoichiometric concerns. Recommendations for future work are also given. Full article

Aluminum metal matrix composites (AMMCs) have become increasingly ubiquitous in the fields of aerospace and automobile businesses due to their lightweight properties. Their machining is a challenging task because of the presence of supplemented particles, also called reinforcements. As the wt% of the supplemented particles changes, the morphological and machining behaviors of the AMMCs change. The present work is focused on exploring the thermo-mechanical properties of AMMCs which would help in AMMC applications in the aerospace industry with a new collection of composites containing silicon carbide (SiC) and zircon/zirconium silicate (ZrSiO₄) as supplements in wt% of 5%, 20%, 30%, and 40%. Uniform binary and hybrid sample pallets are prepared by powder metallurgy (PM). The said samples are sintered and then machined using wire electric discharge machining (WEDM) employing brass wire with a feed rate of 2 to 3 mm/min. Also, analysis of porosity and recast layer formation is performed via the microstructure, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Some interesting and useful findings are obtained which can extend the applications of AMMCs in automobiles and the aerospace industry. The results reveal that temperature and wt% are playing their significant roles in the changes in the thermo-mechanical properties of AMMCs. Mathematical equations via regression analysis using Minitab 17 and Excel are developed for the congruence of experimental data. Analysis of Variance (ANOVA) is also performed. Hence, the most optimized relationships for the best machining output are established and presented in this proposed study. Full article

This study examined the impact of hybrid reinforcement particles, specifically zirconium carbide (ZrC) and tungsten carbide (WC), as well as the parameters of friction stir processing (FSP), on the microstructure, mechanical properties, and dynamic behavior of aluminum alloys. The hybrid particles were integrated into the aluminum alloy using friction stir processing (FSP). The fabricated metal matrix composites (MMCs) were characterized using optical microscopy, scanning electron microscopy (SEM), and dynamic mechanical analysis (DMA). The results showed that the FSP parameters and reinforcement particles played an important role in improving the grain refinement of the MMCs. This study’s results suggest that the FSP samples’ UTS can be maximized using a tool rotation speed of 600 rpm and a traverse speed of 30 mm/min. The grain refinement in the composite surface was attributed to the dynamic recrystallization during the friction stir processing (FSP) process. The reinforcement particles also acted as grain growth restrictors, further refining the grain size. This resulted in a 34% increase in ultimate tensile strength compared to AA2024 alloys and a 12% increase compared to AA7075 alloys. The composite surface also exhibited enhanced dynamic properties, with an increase in impact energy of 26%. The free vibration test showed that the hybrid reinforcement particles significantly improved the strength and damping capacity of the aluminum alloys, resulting in a high resonant frequency. This is important for applications such as vibration damping and noise reduction. Full article

The present paper reports the analyses of results obtained from experiments carried out to explore the challenge of homogeneous, uniform, and deagglomerated dispersion of ultra-heavy nanoparticles (NPs) in the high-performance polyaryletherketone (PAEK) matrix. An equal and fixed amount of (0.5 vol. %) NPs of silicon carbide (SiC), zirconium carbide (ZrC), and tungsten carbide (WC) were dispersed in a PAEK matrix and compression molded to develop three different nanocomposites. Simultaneously, nano-adhesives of the same composition were also developed to join the stainless steel adherends. The composites and adhesives were characterized for their physical, thermal, thermo-mechanical, thermal conductivity (TC), and lap shear strength (LSS) behavior. It was observed that SiC NPs performed significantly better than ZrC and WC NCs in all performance properties (LSS: 154%, TC: 263%, tensile strength: 21%). Thermal conductivity (TC) and tensile properties were validated using various predictive models, such as the rule of mixture parallel model, the Chiew and Glandt model, and the Lewis model. Scanning electron micrographs were used for the morphological analysis of LSS samples to detect macro- and micro-failure. Micrographs showed evidence of micro-striation and plastic deformation as a micromodel, as well as mixed failure, i.e., adhesive–cohesive as a macro-failure mode. Full article