ZrC Particles Research Articles

Microstructure and helium irradiation performance of W–ZrC/Sc2O3 composites prepared spark plasma sintering

W–ZrC composites reinforced with Sc2O3 particles were produced by mechanical milling and subsequent spark plasma sintering. W–ZrC/Sc2O3 composites were exposed to the He ion for 2 h with 50 and 80 eV ion energies and a particle flux of above 1022 m−2 s−1 performed in a Large-power Materials Irradiation Experiment System (LP-MIES). Results showed that W, Sc2O3, and ZrC can combine well with one another to form a solid solution. Small amounts of ZrC particles can effectively capture impurity O in tungsten GBs and form nano-sized ZrO2 particles. After a large He+ ion irradiation, serious radiation damage occurred on the sample surfaces, exhibiting “fuzz” structures. With the increasing in He+ ion energy from 50 eV to 80 eV, the microhardness of the irradiated regions rose, and pores were formed on the affected area. Besides, agglomerated second-phase groups (primary ZrC with slight Sc2O3) tended to distribute outward.

Microstructure and mechanical properties of Mo-ZrC-Cu composites synthesized by reactive melt infiltration of Zr-Cu melt into porous Mo2C preforms at 1300 °C

Mo-ZrC-Cu composites have been synthesized by reactive melt infiltration of Zr-Cu binary alloys into porous Mo2C preforms at 1300 °C for 10 min in argon. The influence of Zr content in the Zr-Cu infiltrator on microstructure and mechanical properties of Mo-ZrC-Cu composites are investigated. The as-synthesized composites consist of three major phases of Mo, ZrC and Cu, after a complete reaction of Mo2C(s) + Zr-Cu(l) → Mo(s) + ZrC(s) + Cu(l). Mo2Zr phase is formed when Zr content exceeds 50 at% in the Zr-Cu infiltrator. The formed ZrC grains have sizes less than 1 μm with Mo solid solute inside. Meanwhile, nanoscale zones enriched in Cu and C are also detected in ZrC grains. The angular ZrC particles and rounded Mo grains become larger with increasing Zr content in the Zr-Cu infiltrator. With decreasing Cu content from 43.5 to 31 vol% in Mo-ZrC-Cu composites, the elastic modulus and flexure strength increase from 146 to 156 GPa and from 542 to 569 MPa, respectively.

Effect of Zr Content on Mechanical Properties of Diamond/Cu-Zr Composites Produced by Gas Pressure Infiltration

Diamond particle-reinforced Zr-alloyed Cu matrix (diamond/Cu-xZr) composites were produced by a gas pressure infiltration route, with x = 0.0, 0.3, 0.5, 0.75, and 1.0 wt.%. The x-ray diffraction, scanning electron microscopy, and transmission electron microscopy characterization confirms the formation of ZrC at the diamond/Cu interface. With increasing Zr content, the tensile, bending, and compressive strengths of the diamond/Cu-Zr composites are found to firstly increase and then decrease. The maximum tensile, bending, and compressive strengths at 0.75 wt.% Zr are 108, 360, and 441 MPa, respectively. The variation of the mechanical properties is attributed to the formation of interfacial ZrC. The increase in amount of ZrC strengthens the interface, but large ZrC particles formed at high Zr content are harmful to the interfacial bonding. The result suggests that the mechanical properties of diamond/Cu composites can be enhanced by Cu matrix alloying with Zr.

Microstructure and properties of C/C–ZrC composites prepared by hydrothermal deposition combined with carbothermal reduction

Carbon fiber reinforced carbon matrix containing ZrC (C/C–ZrC) composites were prepared by hydrothermal deposition combined with carbothermal reduction. The submicron ZrC particles (100–300 nm) were dispersed in the matrix. The stress-strain curves of the composites presented a typical pseudo-plastic fracture behavior. The mass and linear ablation rates of the composites were 3.7 × 10−3 g/s and 4.2 × 10−3 mm/s, respectively. The formation of ZrO2 glass layer reduced erosion of the composites in the ablation center. The continuous C–ZrC–ZrO2 skeleton layer generated from the oxidation of ZrC can protect the composites from erosion at the ablation brim region. The obtained C/C–ZrC composites present a promising potential as ablation resistance materials.

Fabrication of TiC–ZrC–Co composites with refined microstructure using ultrafine TiC–ZrC mixture powders

Ultrafine TiC–ZrC mixture powders with various Ti/Zr molar ratios (9:1, 8:2, 7:3, and 6:4) were synthesized by carbothermal reduction of high–energy milled TiO2–ZrO2–C. ZrC was found to be insoluble in the TiC lattice at 1400–1500 °C; as a result, carbothermal reduction of TiO2–ZrO2–C mixtures led to the formation of the TiC–ZrC mixture powders rather than the (Ti,Zr)C solid solution. TiC–ZrC–Co composites prepared using the TiC–ZrC mixture powders exhibited a refined microstructure, due to the inhibition of the coalescence of TiC grains by ZrC grains distributed in the TiC–ZrC mixture powders. In other words, the ZrC particles distributed in the mixture powders inhibited the coalescence of TiC grains during liquid–phase sintering, resulting in the formation of TiC–ZrC–Co composites with refined microstructure. The refined microstructure of these composites favorably influenced their properties: in particular, the experimental measurements highlighted a significant improvement in the mechanical properties (HV = 14.8–16.0 GPa, KIC = 7.2–7.6 MPa m1/2) of the composites prepared from the ultrafine TiC–ZrC mixture powders, compared with those (HV = 11.1–13.3 GPa, KIC = 5.7–6.3 MPa m1/2) of conventional TiC–ZrC–Co composites.

Vacuum brazing of TZM alloy to ZrC particle reinforced W composite using Ti-28Ni eutectic brazing alloy

Reliable brazing of TZM alloy and ZrC particle reinforced (ZrCp) W composite was achieved in this study by using Ti-28Ni eutectic brazing alloy. The typical interfacial microstructure of TZM/Ti-28Ni/ZrCp-W brazed joint consisted of a Ti solid solution (Ti(s, s)) layer, a continuous Ti2Ni layer and a diffusion layer mainly composed of W particles and (Ti, Zr)C particles. With an increase of brazing temperature, more ZrC particles and W particles entered the molten brazing alloy, which broadened the brazing seam and diminished the Ti2Ni layer, resulting in the disappearance of the Ti2Ni layer eventually. Meanwhile, more Ti(s, s) stripes were observed on the TZM side. The presence of continuous Ti2Ni intermetallic phase and Ti(s, s) stripes structure in joints deteriorated the joining properties, which resulted in the formation of brittle fracture under shear test. In addition, the fracture path was related to the brazing temperature, and cracks initiate and propagate in the continuous Ti2Ni layer at lower temperatures. However, the fracture path tended to be located at the TZM substrate close to the interface between TZM and the brazing seam when the brazing temperature exceeded 1040°C. The optimal room temperature shear strength reached 120.5MPa when brazed at 1040°C for 10 min and the fracture surface exhibited cleavage fracture characteristics, and the shear strength at high temperature of 800°C for the specimens with highest shear strength at room temperature reached 77.5MPa.

Mechanism of Zr in in situ-synthesized particle reinforced composite coatings by laser cladding

By adding mixture of ZrO2 and carbon, a Zr-enhanced composite coating was produced onto an AISI 1045 substrate by laser cladding. The microstructure and phase formation, microhardness and wear resistance of the composite coating were studied. The experimental results indicate that the composite coating with metallurgical bonding to substrate consists of γ-Ni, massive ceramic particles of ZrC, NiZr2, Ni7Zr2, (Fe, Ni)23C6 and Fe3C. The in situ-synthesized ZrC particles are uniformly dispersed in composite coating, which refines the microstructure of composite coating. With different ZrO2 and carbon additions, the properties are improved differently. Finally, the fine in situ ZrC particles improve the microhardness of composite coating to HV0.2 650, which is nearly 2.7 times that of Ni25 coating. Also, the composite coating has an advantage in wear resistance; it offers better wear resistance when more mixture of ZrO2 and carbon was added in nickel alloys.

Microstructure, hardness and fracture toughness of spark plasma sintered ZrB2–SiC–Cf composites

Abstract The combined effects of SiC particles and chopped carbon fibers (C f ) as well as sintering conditions on the microstructure and mechanical properties of spark plasma sintered ZrB 2 -based composites were investigated by Taguchi methodology. Analysis of variance was used to optimize the spark plasma sintering variables (temperature, time and pressure) and the composition (SiC/C f ratio) in order to enhance the hardness of ZrB 2 –SiC–C f composites. The sintering temperature was found as the most effective variable, with a significance of 83%, on the hardness. The hardest ZrB 2 -based ceramic was achievable by adding 20 vol% SiC and 10 vol% C f after spark plasma sintering at 1850 °C for 6 min under 30 MPa. Fracture toughness improvement were related to the simultaneous presence of SiC and C f phases as well as the in-situ formation of nano-sized interfacial ZrC particles. Crack deflection, crack branching and crack bridging were detected as the toughening mechanisms. A Vickers hardness of 14.8 GPa and an indentation fracture toughness of 6.8 MPa m 1/2 were measured for the sample fabricated at optimal processing conditions.

Surface modification and characterization of zirconium carbide particulate reinforced C70600 CuNi composite fabricated via friction stir processing

In the present research work, Friction stir processing (FSP) technique has been applied to develop a C70600 graded copper-nickel (CuNi) Surface metal matrix composite (SMMC) reinforced with and without addition of ZrCp. Rotational and traverse speeds were set as 1200 rpm and 30 mm/min, respectively. The fabricated SMMC were metallurgically characterized by using Optical microscope (OM) and Field emission scanning electron microscope (FESEM). The homogeneous distribution of ZrC particles and good interfacial bonding between matrix/reinforcement were observed via OM and FESEM microscopes. The microhardness of the CuNi/ZrC surface composite was observed by using microhardness tester at the cross section of the sample. The average higher microhardness of 148 Hv at CuNi/ZrC SMMC and lower microhardness of 115 Hv at FSPed CuNi was found. The Ultimate tensile strength (UTS) value was measured by using micro tensile testing machine. The UTS value of CuNi/ZrC composite and FSPed CuNi were observed to be 310 MPa and 302 MPa, respectively. The mode of fracture was also observed via FESEM. The X-ray diffraction (XRD) test was carried out to confirm the presence of CuNi & ZrC in the SMMC layer.

Effects of precursor concentration on the microstructure and properties of ZrC modified C/C composites prepared by precursor infiltration and pyrolysis

To improve the ablation resistance of C/C composites, ZrC modified composites were fabricated by precursor infiltration and pyrolysis combined with gradient chemical vapor infiltration process. The effects of ZrC precursor concentration on the microstructure, mechanical and ablation properties of the composites were studied. Results showed that with the increase of ZrC precursor concentration, the ZrC content and macroscopic uniformity of the composites increased but with obvious ZrC particle aggregation and the flexural strength decreased gradually. As the concentration of ZrC precursor improved to 60%, the fracture mode of the composites transformed from toughness to brittleness which was mainly attributed to the improved graphitization degree and reaction damage of carbon fiber in the precursor pyrolysis process. However, the ablation resistance was enhanced with the increasing precursor concentration which was resulted from the formation of ZrO2 in center ablation region and continuous ZrO2 coating in brim region serving as a barrier to heat and oxygen transfer.

Effects of low-temperature thermal cycling treatment on the microstructures, mechanical properties and oxidation resistance of C/C-ZrC-SiC composites

Carbon/Carbon (C/C) composites modified with ZrC and SiC particles were prepared by precursor infiltration and pyrolysis (PIP) process. Effects of the simulated low earth orbit environment including the vacuum environment (under the high-vacuum state of 1.3 × 10−3 Pa) and low-temperature thermal cycling (the temperature is ranged from 153 K to 393 K for 200 times) on C/C-ZrC-SiC composites were investigated. These results show that the significantly generated microcracks, interspaces and interface debondings contributed to the increase of open porosity. The interfacial damages of C/C-ZrC-SiC composites caused by low-temperature thermal cycling in short-cut webs and non-woven webs were generated at fiber/matrix interface and fiber bundle/matrix interface, respectively. The flexural strength of C/C-ZrC-SiC composites increased by 9.35% after 100-time thermal cycles and then decreased dramatically to 83.99% of pristine strength after 200-time thermal cycles, accompanied by the transformation of fracture behavior from the brittle fracture mode into the pseudo-plastic fracture mode. In addition, the defects induced by the low-temperature thermal cycling accelerated the oxidative damage of C/C-ZrC-SiC composites during thermal shock between 1773 K and room temperature.

Effect of ZrC particle size on the ablation resistance of C/C-ZrC-SiC composites

C/C-ZrC-SiC composites with different ZrC particle size was fabricated by organic precursor infiltrations and pyrolysis (PIP) combined with additional heat treatment at different temperatures and further PIP of SiC precursor. Effect of ZrC particle size on the ablation resistance of C/C-ZrC-SiC composites was investigated under heat flux of 4.18±0.42MW/m2 containing high scouring. Results showed that small ZrC particle size (0.2μm) caused low viscosity and unfavorable anti-scouring of the formed oxides, leading to unsatisfactory ablation resistance of the composites. Oxides for composites with big ZrC particles (2μm) failed to seal large gaps between ZrC particles, resulting in massive ablation of the composites. Composites with ZrC particle size of around 1μm showed good ablation resistance, with linear ablation rate decreased by 91.3% relative to C/C-ZrC-SiC composites with ZrC particle size of 200nm. The good ablation resistance was mainly ascribed to the formed viscous oxides containing particles, which could resist scouring and meanwhile seal gaps in composites during ablation.

Dry Sliding Tribological Behavior at Elevated Temperature of In Situ Aluminum Matrix Composites Fabricated by Al-ZrO2-C System with Different Mole Ratio of C/ZrO2

The tribological behavior of the composites fabricated by an Al-ZrO2-C system with different mole ratios of C/ZrO2 at elevated temperature in air atmosphere were investigated by using a pin-on-disc wear tester. The reinforcement amounts and kinds of the composites varied with molar ratio of C/ZrO2. With the increase of the molar ratio of C/ ZrO2 from 0 to 1, the Al3Zr blocks decrease gradually and almost disappear finally. On the contrary, the ZrC particles form and increases in its amount. At elevated temperature, the composites have similar variation trend in the mass loss varied with sliding velocity and applied load, respectively. When the test temperature is at 373 K, the mass loss increases with increasing the sliding velocity, and when the sliding velocity is around 0.6 m/s, the mass loss increases to a maximum value and then decreases with further increase in sliding velocity. However, the mass loss always decreases with increasing the sliding velocity at 473 K. With the increase of C/ZrO2 molar ratio, the wear resistance of the composite increases and its friction coefficient decreases. The metal flows and adhesive wear become the main wear modes with increasing the applied load and test temperature.

Influence of ZrC on the microstructure of its surrounding resin-based carbon at high temperature

The microstructures of a refractory ZrC particle and its surrounding resin-based carbon treated above 2500 °C were investigated by SEM, TEM, HRTEM and selected area electron diffraction. Results show that the ZrC particle is enclosed by a transition carbon layer that has a d002 of 0.3375 nm, close to that of ideal graphite, indicating the formation of a well graphitized structure. The carbon far away from the ZrC particle remains isotropic and amorphous. These results are verified by selected area electron diffraction, and can be attributed to catalytic graphitization and stress-induced graphitization.

Investigation of template effect on zirconium carbide synthesis process in carbothermal method at low temperature condition

The template effect of carbon source precursors on ZrC synthesis at low temperatures were investigated by carbothermal reduction of ZrCl4 using metallic sodium. The polymerization of naphthalene or toluene in the presence of ZrCl4 was directed to formation of two ZrC products including nanorods and nanoparticles. The polymerization behavior of naphthalene or toluene had template effects on ZrC shaping. The ZrC nanorods/nanoparticles were characterized by X-ray and SEM. The results showed that ZrCl4 in both condition was completely transformed to ZrC, after heat treatment in argon at temperatures above 600°C. The SEM study revealed that the nucleation and growth of ZrC nanorods/nanoparticles occurred on the surface of derived polymer from naphthalene/toluene. There was no carbon residue from naphthalene/toluene in the products. The obtained ZrC particles exhibited face-centered cubic lattice structure and narrow size distributions.

Tungsten-zirconium carbide-rhenium alloys with extraordinary thermal stability

The low recrystallization temperature (1200°C) of pure W is a serious limitation for application as facing plasma materials in fusion reactor. In this paper, W-0.5wt.%ZrC-1wt.%Re (WZR) alloy with recrystallization temperature up to 1800°C was prepared by mechanical milling and spark plasma sintering. The grain size of WZR alloy is about 2.6μm, smaller than that of pure W (4.4μm), which keeps unchanged until the annealing temperature increases to 1800°C. Tensile tests indicate that the WZR alloys exhibit excellent comprehensive properties: the ductile to brittle transition temperature of WZR is in the range from 400°C to 500°C, about 200°C lower than that of pure W prepared by the same process; the total elongation (TE) of WZR at 600°C is above 30%, which is about 2 times that of pure W (at 700°C). Meanwhile its tensile strength keeps ∼450MPa before and after 1800°C annealing as well as its TE increases after annealing. WZR alloy exhibits higher hardness (489HV) than that of pure W (453HV) at room temperature. Microstructure analysis indicates that the strengthening of nano-sized ZrC particles dispersion and Re solid solution improve tensile properties and thermal stability of WZR alloy.

Synthesis of a soluble preceramic polymer for ZrC using 2-hydroxybenzyl alcohol as carbon source

A preceramic polymer for ZrC was successfully synthesised by chemical reaction between zirconium oxychloride (ZrOCl2·8H2O) and 2-Hydroxybenzyl alcohol via a one-pot route. The molecular structure, thermal properties and pyrolysis behaviour of the precursor were investigated. The results indicated that the precursor might be Zr–O–Zr chain polymer with 2-Hydroxybenzyl alcohol as ligand. The precursor was air-stable and exhibited excellent solubility in common organic solvents. The conversions from precursor to ZrC powders were investigated by TG-DTA, X-ray diffraction, Scanning electron microscope, TEM and Raman spectrum. The precursor underwent a thermal decomposition in four steps, and ZrC powders were formed at 1300°C via carbothermal reduction reaction of ZrO2 and carbon in argon with ceramic yield of 63.0%. The ZrC particles were fine and exhibited irregular polyhedron morphology with average size in the range of 100–300 nm.

Synthesis and microstructure of continuous composite ceramic fibres of ZrC/ZrB2–SiC derived from polymeric precursors

Continuous composite ceramic fibres of ZrC–SiC and ZrC–ZrB2–SiC were synthesized via melt spinning and pyrolysis of a novel polymeric precursor, polyzirconocenecarbosilane (PZCS), with or without the addition of polymethylaminoborazine (PBN) as a boron source. The resultant fibres had mass concentrations of zirconium carbide, diboride, or both of approximately 15%. Their microstructures exhibited nanoscale ZrC and ZrB2 particles dispersed in a continuous SiC matrix containing free carbon. The tensile strength of the fibres was approximately 1GPa.

Fabrication and microstructure of 3D Cf /ZrC-SiC composites: through RMI method with ZrO2 powders as pore-making agent

3D Cf/ZrC–SiC composites were prepared by a combination process of slurry infiltration and reactive melt infiltration. ZrO2 powders and ZrSi2 alloy, both of which reacted with amorphous carbon, were used as pore-making agent and infiltrator, respectively. After carbothermal reduction at 1650°C, X-ray diffraction analysis revealed that ZrO2 powders were completely converted into ZrC by reacting with amorphous carbon, and an in-situ formed submicron porous configuration was observed at the areas containing ZrO2. Results showed that the matrix in composites mainly consisted of SiC, ZrC and a small quantity of residual metal. SEM and TEM images revealed the formation of ZrC or SiC intergranular particles in the matrix and the characteristic around the residual resin carbon. The composites had a bending strength of 94.89±16.7MPa, fracture toughness of 11.0±0.98MPam1/2, bulk density of 3.36±0.01g/cm3, and open porosity of 4.64±0.40%. The formation mechanisms of ZrC–SiC dual matrix and intrabundles׳ structure were discussed in the article.

The effect of thermomechanical treatment regimes on microstructure and mechanical properties of V–Me(Cr, W)–Zr–C alloys

The regularities of the formation of a heterophase structure in dispersion-strengthened vanadium V–Me(Cr, W)–Zr–C alloys are studied as a function of the regimes of their thermomechanical treatment. The regimes of treatment providing a substantial increase in the dispersity and homogeneity of spatial distribution of ZrC particles, temperature of recrystallization, and high-temperature (at T = 800°C) short-time strength are found in comparison to conventional treatment regimes.