ZrB2 Content Research Articles

Mechanical, Corrosion and Wear Characteristics of Cu-Based Composites Reinforced with Zirconium Diboride Consolidated by SPS

This study aimed to investigate the physical, mechanical, corrosion, and tribological properties of Cu-based composites with varying zirconium diboride content. The composites were successfully consolidated using spark plasma sintering (SPS) at temperatures of 850 °C and 950 °C and a pressure of 35 MPa. The effect of the ZrB2 content and the sintering temperature on the properties of the Cu-based composites was investigated. Scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-ray diffraction were used to analyse microstructure evolution in copper matrix composites. Microhardness tests were used to evaluate mechanical properties. Wear behaviour was evaluated using a ball-on-disc method. Corrosion properties were estimated on electrochemical tests, such as potentiodynamic polarisation. The results demonstrated an enhancement in the density and porosity of the composites as the sintering temperature increased. A uniform dispersion of ZrB2 was observed in the copper matrix for all composites. With an increase in the content of the ZrB2 reinforcement phase, there was an increase in microhardness and an improvement in the wear resistance of the sintered composites. A reduction in densification and corrosion resistance of Cu-based composites was observed with increasing ZrB2 content.

Microstructure and mechanical properties of ZrB2 ceramic particle reinforced AlCoCrFeNi high entropy alloy composite materials prepared by spark plasma sintering

In this study, xZrB2-AlCoCrFeNi (x = 0,5,10,15) (wt%) based high entropy alloy (HEA) composites were prepared by Spark Plasma Sintering (SPS). The influence of ceramic particle ZrB2 content on the densification behavior, microstructural evolution, and mechanical properties of the composites was investigated through scanning electron microscopy, X-ray diffraction, and mechanical performance testing. The results indicate that the HEA composites undergo a phase transformation, from (FCC + BCC + B2) structure to (FCC + BCC + B2+Laves) structure with the addition of ZrB2. The incorporation of ZrB2 facilitates the emergence of the Cr precipitate phase, and the grain size of this phase enlarges as the ZrB2 content rises. Additionally, when the ZrB2 content is 10 %, the maximum compressive strength reached 2071 MPa. Furthermore, at the ZrB2 content of 15 %, the composite material achieves a maximum densification of 99.13 % and a maximum hardness of 1222.2 HV.

Enhanced mechanical properties and corrosion resistance of electro-deposited NiCoP composite coatings with ZrB2 particle addition

This work was initiated with the purpose of expanding the utilization of nickel-based composite coatings, especially in wear and corrosion-related industrial applications. NiCoP coatings have long attracted scientific and engineering interest due to their enhanced mechanical properties reinforced by incorporation with a reinforcement phase. In the present study, NiCoP composite coatings reinforced with ZrB2 ceramic particles were synthesized by direct current deposition using a modified Watt’s type bath. The microstructures of composite coatings were studied by x-ray diffraction analysis, energy dispersive x-ray spectroscopy, and scanning electron microscopy, respectively. The hardness and tribological properties of the composite coatings were evaluated and compared. The corrosion behaviors of the deposits were investigated using electrochemical spectroscopy and potentiodynamic polarization techniques in simulated seawater. The effect of ZrB2 content on the microstructures and mechanical properties of the composite coatings was explored and discussed. The present study indicates that there is a progressive enhancement in the hardness, corrosion resistance, and wear resistance of the composite coatings with the increase in ZrB2 loading. The NiCoP-12 g/l-ZrB2 coating possesses the highest microhardness and superior wear performance, while the NiCoP-6 g/l-ZrB2 coating exhibits the best anti-corrosion properties. The present study shows a cost-effective and feasible solution for the preparation of NiCoP protective coatings with enhanced properties, which holds great potential for industrial applications requiring wear and anti-corrosion protection.

ZrB2-Copper-Graphite Composite for Electric Brushes: Positive Effect of ZrB2 Addition on Composite Properties.

A ZrB2-copper-graphite composite was produced through powder metallurgy and was tested as a new electric brush material. The aim of this paper was to study the effect of ZrB2 addition on the composite's properties. Besides its physical properties such as density and resistivity, its mechanical properties, such as hardness, bending strength and wear resistance, were studied. A scanning electron microscope (SEM) was used to study the morphology of the wear surface, and a configured energy-dispersive spectrometer (EDS) was used to research the chemical composition of the samples. The results showed that, with the addition of ZrB2, the composite's properties such as density, resistivity, hardness, and bending strength improved significantly. Compared with samples without ZrB2, samples with the addition of 4% ZrB2 achieved a hardness of 87.5 HRA, which was improved by 45.8%, and a bending strength of 53.1 MPa, which was increased by nearly 50.0%. Composites with 1% content of ZrB2 showed the best wear resistance under non-conductive friction; however, under conductive friction, composites with 4% content of ZrB2 showed better wear resistance.

High temperature oxidation behavior of liquid phases sintered SiC ceramics with ZrB2 addition

The oxidation property of liquid-phase sintered silicon carbide (LPS-SiC) ceramics with ZrB2 addition was studied after oxidation test in air at 1400 °C. The results indicate that the addition of ZrB2 decreased the degree of polymerization (DOP) of the silicate networks in the oxide layer, suppressing the additional oxidation caused by residual bubbles in the oxide layer of LPS-SiC, which bypassed the layer and directly corroded the material internally. After 100 h of oxidation, the additional oxidation depth was found to be 125 μm in the sample without ZrB2 and 0 μm in those containing 10 wt% ZrB2. Simultaneously, the decrease in DOP facilitates the migration of crystalline phases. The generated ZrSiO4 can migrate and aggregate at the interface between the surface oxide layer and the SiC/ZrB2 matrix, forming a continuous ZrSiO4 barrier. This impedes the diffusion of the oxidant and enhances the oxidation resistance. However, an insufficient ZrB2 content leads to a discontinuous ZrSiO4 layer, thereby weakening its protective effect. Simultaneously, a decrease in DOP increases the rate of oxygen diffusion, resulting in an increase in the oxidation layer thickness. This study contributes to a better understanding of the failure mechanisms of LPS-SiC in oxidizing environments and provide a reference for the design of oxidation-resistant LPS-SiC materials.

High temperature friction and wear behavior of Mo–Si–B/ZrB2 composites

The Mo–Si–B alloys with good wear resistance are prominent for high-temperature applications. In this work, the effects of ZrB2 content and test temperature on the tribological properties of the Mo–Si–B/ZrB2 composites at 25–800 °C were investigated. It indicates that the composites show an enhanced wear resistance, which can be ascribed to the improved hardness and formation of Zr-rich borosilicate layer by introducing ZrB2 particles. The main wear mechanism is abrasive wear accompanies with adhesive wear at 25–400 °C, where ZrB2 addition can reduce the wear loss. And adhesive wear dominates at 600–800 °C, where the formed tribo-layer can provide a good self-lubricity and is beneficial for improving the wear resistance of the composites.

A universal strategy towards the fabrication of ultra-high temperature ceramic matrix composites with outstanding mechanical properties and ablation resistance

Materials with both excellent mechanical properties and good ablation resistance are urgently needed for the applications of thermal protection system in extreme high temperature oxidizing environments. However, owing to the lack of efficient fabrication processes, the existing materials suffer from either insufficient mechanical properties or poor ablation resistance. Herein, we report a novel solid–liquid combination fabrication strategy that successfully achieves the efficient incorporation of ultra-high temperature ceramics into 3D continuous carbon fiber performs as well as rapid densification. The relative density of the green body approaches the cubic close packing of spherical particles. Using Cf/ZrB2–SiC as an example, the as-prepared composite exhibits outstanding mechanical properties with a flexural strength surpasses 600 MPa and an unprecedented work of fracture of 11,851 ± 838 J/m2, which is two orders of magnitude higher than that of the currently reported monolithic ultra-high temperature ceramics. Moreover, the high ZrB2 content endows the composites with excellent ablation resistance and is thus capable of maintaining long-term non-ablative conditions at 2500 °C. The strategy possesses remarkable universality and high design flexibility, providing a time-saving and cost-effective universal strategy for the on-demand design and fabrication of high-performance ceramic, carbon, metal, and polymer matrix composites.

Fabrication and improved properties of ZrC-SiC-ZrB2 ceramics by ultra-high pressure sintering

ZrC-SiC-ZrB2 ceramics were prepared via ultra-high pressure sintering under 15 GPa at 1200 °C. The densification mechanism, microstructures, and properties of the prepared ceramics were investigated. The sintered ceramics with ZrB2 content of 15 vol% showed the improved comprehensive mechanical properties, including Vickers hardness of 26.6 GPa, Young's modulus of 469.1 GPa, and fracture toughness of 5.0 MPa·m1/2, which was 86.7% higher than that of pure ZrC ceramics. In the sintered sample, the ultra-high pressure induced new microstructure, such as L-C lock in ZrC phase, stacking faults and nanotwins in SiC phase, and severe lattice distortion in ZrB2 phase, jointly contributed to the improvement in Vickers hardness. Deflection and bridging during crack propagation were ascribed to the uniform combination of various phases.

The effects of partially or fully linked boron with a cross-linking structure of an organic precursor on the purity and morphology of ZrB2 powder.

From a chemical infrastructure perspective, it is important to ensure that all ions constituting a target product, e.g., Zr and B ions for ZrB2, are fully linked with a cross-linking structure for synthesis via an organic precursor. In the present study, glycerol is used as a chelating ligand to prepare boron both partially and fully linked with the cross-linking structure of organic precursors by a sol-gel route. The results are far from expected, in that the more linked boron there is in the precursor, the purer the ZrB2 produced. In the case of a partially linked cross-linking structure, the carbothermic reduction reaction for ZrB2 is a multi-step process with an intermediary phase of ZrC, and then a high-purity prism-like ZrB2 powder with a larger size is obtained. A minimum of 0.26 wt% for the oxygen content of ZrB2 corresponds to a 0.67 molar ratio of glycerol to H3BO3. On the other hand, in the case with the boron fully linked, a single-phase of ZrB2 cannot be obtained, and instead a double-phase is obtained. Therefore, the amount of impurity is greater, even though the size is smaller. The carbothermic reduction reaction is direct, and has only one step.

Influence of ZrB2 on Si3N4 ceramics prepared by Si nitridation and hot‐pressing process

AbstractThis work investigated the effect of ZrB2 content on phase composition, relative density, microstructure, and mechanical performance of Si3N4 ceramics prepared by Si nitridation and hot‐pressing method. Si3N4 ceramics were fabricated using Si powder by nitridation and hot‐pressing process. Results showed that the addition of ZrB2 enhanced the transformation of α‐Si3N4 into β‐Si3N4 phase during nitridation, resulting in a greater fraction of β‐Si3N4 (above 90 wt.%) phase in Si3N4 ceramics with ZrB2 after hot‐pressing. In contrast, ceramics without ZrB2 had a lower ratio of β‐Si3N4 (40.4 wt.%). The use of 2.5 vol.% ZrB2 yielded a significant bimodal microstructure and increased fracture toughness to 5.0 ± 0.2 MPa·m1/2, but decreased Vickers hardness to 16.4 ± 0.5 GPa. However, increasing the ZrB2 content to 5 vol.% and 10 vol.% led to a massive formation of equiaxed coarse β‐Si3N4 grains and a significant decrease in Vickers hardness and fracture toughness.

Ablation resistance of ZrO2-encapsulated ZrB2 coating with 3D thermal conduction network applied over carbon/carbon composites

In this work, ZrO2 with different ZrB2 contents (0, 15, 30,40 wt%) composite powders were synthesized by sol-gel, then they were sprayed on carbon/carbon composites using plasma spraying to construct a three-dimensional (3D) thermal conduction network within the formed coating. Oxyacetylene ablation tests were carried out under 4.2 MW/m2 to investigate the effect of the 3D thermal conduction network on the ablation resistance of coated samples. The encapsulation structure formed during sol-gel process benefits to slowing the oxidation rate of ZrB2 and the content of ZrB2 is critical for establishing a stable 3D thermal conduction network within the coating.

Effect of ZrB2 on promoting the phase transformation mechanism of Si3N4-based ceramics at low temperature

In this study, the mechanism of the effect of ZrB2 on phase transformation of Si3N4 at a low temperature and the influence of its content on Si3N4-based ceramics were investigated. Previous study has shown that oxide impurities, i.e., B2O3 and ZrO2 on ZrB2 particles, alone cannot contribute to phase transformation of Si3N4 at a low temperature. But, the introduction of 0.5 vol% ZrB2 into Si3N4 ceramics can promote the α-β phase transformation of Si3N4, which is confirmed to be the role of boron by comparison of the experimental results obtained from the addition of 0.5 vol% Zr and 0.5 vol% B. Increasing the ZrB2 content from 0 vol% to 2.5 vol% intensifies the α-β phase transformation while decreasing the α phase content of Si3N4-based ceramics, accompanied by a slight grain growth, leading to a decrease in hardness. At the same time, aspect ratio and the quantities of elongated grains per square micron increase, and thus the fracture toughness increases significantly. However, when the content of ZrB2 increases to 5 vol%, the Si3N4-based ceramics not only have a substantial decrease in hardness, but also the fracture toughness fails to be effectively improved due to high porosity and the decrease in aspect ratio and the quantity of elongated grains per square micron. The current study demonstrates that the dense Si3N4-based ceramics with high hardness and toughness (hardness ∼19.9 ± 0.2 GPa, toughness ∼6.27 ± 0.19 MPa m1/2) can be prepared successfully at 1600 °C by introducing 0.5 vol% ZrB2.

Effect of ZrB2 and Polyvinyl Butyral Content on the Oxidation Resistance of ZrB2–SiC Coatings Produced by Slurry Brushing Method

ZrB2–SiC coatings are prepared on the surface of graphite by slurry brushing method to improve the oxidation resistance. Effects of ZrB2 content and polyvinyl butyral (PVB)–ethanol solution concentration on microstructure and static oxidation behavior of the ZrB2–SiC coatings are investigated at 1200 °C in air. The results indicate that increasing ZrB2 content improves the oxidation resistance of the coatings. When ZrB2 content increases from 30 to 45 wt%, weight loss rates of the coated samples after oxidation at 1200 °C for 120 min decrease from −0.92% to −1.67%. Increasing binder solution concentration raises component content in the coatings. As PVB–ethanol binder concentration increases from 0.025 to 0.075 g mL−1, weight loss rates of the coated samples after oxidation at 1200 °C for 120 min decrease from 0.32% to −0.38%. Excellent oxidation resistance of ZrB2–SiC coating is attributed to self‐sealing ability of B2O3 and borosilicate glass. The composite glass can inhibit oxygen diffusion by filling defects in the coating promptly. The borosilicate glass phase can enhance the fluidity of the composite glass. ZrO2 and ZrSiO4 particles restrict the growth of the microcrack, which improves the oxidation resistance of ZrB2–SiC coating.

Microstructure and tribological properties of ZrB2-enhanced NiCrBSi coatings prepared by high-velocity oxy-fuel spraying

This paper presented a novel study of the preparation of ZrB2-enhanced NiCrBSi coatings and its microstructure and tribological properties. NiCrBSi-ZrB2 composite powder and coatings with ZrB2 contents of 20 %, 40 %, and 50 % were prepared by spray-drying and high-velocity oxygen-fuel (HVOF) spraying, respectively. The microstructure and high-temperature wear performance at 700 °C were compared with those of an NiCrBSi coating. The results showed that the NiCrBSi and ZrB2 powder exhibited good wetting properties in the solid-liquid sintering zone and the CrB phase was formed in the liquid phase contact zone in composite coatings with ZrB2 contents of 20 % and 40 %, while the CrB phase disappeared in the 50 %ZrB2 coating due to the pinning effect caused by excessive ZrB2. The microhardness of composite coatings tended to increase, then decrease, and the 40%ZrB2 coating reached a maximum hardness of 874 HV. The NiCrBSi coating presented oxidative wear and adhesive wear. Although the fracture toughness of composite coatings was lower than that of the NiCrBSi coating, the wear resistance in the composite coating was significantly enhanced due to the evenly distributed ZrB2 and CrB phases. The 20%ZrB2 coating with low fracture toughness and the 50 %ZrB2 coating with hardness mismatch caused by the absence of CrB produced severe abrasive wear. The hardness gradient with the matrix, ZrB2 and CrB phases reduced abrasive wear caused by peeling in 40%ZrB2 coating, and the ceramic phases acted as skeletons reducing the deformation of the load contact area. The formation of Cr2O3 during the friction process further improved the wear resistance. The wear mechanism of 40%ZrB2 coating underwent light adhesive wear, mild abrasive wear and oxidative wear, and the coating exhibited the best wear resistance with the lowest wear rate of 1.16 × 10−13 m3/N·m (a decreased of 56 %).

Effect of ZrB2 on the microstructure, mechanical and tribological properties of Mo–Si–B matrix composites

Composites with good mechanical and tribological properties are in high demand for engineering applications. Toward this aim, the Mo–12Si–8.5B alloy with 2.5–10 wt% ZrB2 ceramic was prepared. The effects of the ZrB2 content on the microstructure, mechanical properties, and tribological behavior were thoroughly investigated. The composites exhibited reduced density and enhanced hardness and strength owing to the dispersion strengthening of ZrB2 particles, thus resulting in improved wear resistance. The frictional properties are highly dependent on the ZrB2 content and counterpart materials. When coupled with GCr15 steel, it shows much slighter abrasive and adhesive wear; therefore, it presents a more preferable anti-wear performance. The wear rate of the composite with 7.5 wt% ZrB2 showed a minimum value of 2.71 × 10−7 mm3N−1m−1.

Synergistic reinforcement effects of ZrB2 on the ultra-high temperature stability of Cf/SiC composite fabricated by liquid silicon infiltration

A carbon fiber-reinforced silicon carbide (Cf/SiC) composite was fabricated with ZrB2 via the liquid silicon infiltration (LSI) method. A prepreg was prepared by impregnating the phenolic resin with the ZrB2 powder. The as-LSIed composites were tested for 5 min with an oxyacetylene torch to evaluate their ablation and oxidation properties under an ultra-high temperature environment. The ZrB2 powders and SiC matrix between carbon fiber bundles generated a dense ZrO2-SiO2 layer, which inhibited further oxygen diffusion into the composite and minimized the ablation and oxidation of the carbon fibers. Weight loss and linear ablation rate were further reduced with the addition of ZrB2 to the Cf/SiC composite; moreover, the synergistic effect of ZrB2 and SiC reinforced the ablation properties with increased ZrB2 content. ZrB2 also reduced the amount of residual silicon, which was detrimental to the mechanical properties of Cf/SiC composite.

ZrB2/SiCN Thin-Film Strain Gauges for In-Situ Strain Detection of Hot Components.

The in-situ strain/stress detection of hot components in harsh environments remains a challenging task. In this study, ZrB2/SiCN thin-film strain gauges were fabricated on alumina substrates by direct writing. The effects of ZrB2 content on the electrical conductivity and strain sensitivity of ZrB2/SiCN composites were investigated, and based on these, thin film strain gauges with high electrical conductivity (1.71 S/cm) and a gauge factor of 4.8 were prepared. ZrB2/SiCN thin-film strain gauges exhibit excellent static, cyclic strain responses and resistance stability at room temperature. In order to verify the high temperature performance of the ZrB2/SiCN thin-film strain gauges, the temperature-resistance characteristic curves test, high temperature resistance stability test and cyclic strain test were conducted from 25 °C to 600 °C. ZrB2/SiCN thin-film strain gauges exhibit good resistance repeatability and stability, and highly sensitive strain response, from 25 °C to 600 °C. Therefore, ZrB2/SiCN thin-film strain gauges provide an effective approach for the measurement of in-situ strain of hot components in harsh environments.

Dielectric and microwave absorption properties of ZrB2 / Al2O3 ceramic composite

ABSTRACTElectromagnetic pollution has become a major problem affecting human health, which requires the scientific community to characterise materials that can solve this problem. In the present work, we studied the microwave absorption properties and complex permittivity of ZrB2/Al2O3 ceramic composites in the X-band by simulation. The composites studied are based on alumina and reinforced with ZrB2 particles. The concentration of ZrB2 particles by volume in these composites are 0%, 5%, 10% and 15%. The results obtained show, on the one hand, that the complex permittivity depends on the frequency, and on the other hand, the high content of ZrB2 remarkably increases the complex permittivity and improves the microwave absorption properties. The ZrB2/Al2O3 composite with 5% by volume of ZrB2 particles has better microwave absorption property than others. In this case, the minimum reflection loss is −26.36 dB at 11.5 GHz. For this composite, the RL bandwidth of less than −10 dB is 1.72 GHz, and it is obtained in the frequency range from 9.4 GHz to 10.5 GHz. The simulation results are in good agreement with the published experimental results. In addition, they indicate that the composites studied are favourable for microwave absorption applications in the X band.

A study on fine Nbss/γ-(Nb,X)5Si3 eutectic with significantly improved room-temperature fracture toughness by added ZrB2

Four NbSi based ultrahigh temperature alloys with compositions of Nb-16Si-20Ti-1ZrC-xZrB2 (x = 0, 0.5, 1, 3) (at.%) were prepared by vacuum non-consumable arc melting. The microstructure evolution, fracture toughness, and fracture behavior of four alloys were investigated. Results showed that four alloys consisted of Nbss, γ-(Nb,X)5Si3, and (Nb,X)3Si phases. The low content of ZrB2 facilitates the disintegration of (Nb,X)3Si, while the high content of ZrB2 stabilizes (Nb,X)3Si. The maze-like Nbss/γ-(Nb,X)5Si3 eutectic structure forms in Nb-16Si-20Ti-1ZrC-0.5ZrB2 alloy. With the increase of ZrB2 content, the room-temperature fracture toughness of Nb-Si-Ti-ZrC-based alloy increases and decreases. When the addition amount of ZrB2 is 0.5 at.%, the room-temperature fracture toughness is the largest of 18.4 MPa·m1/2, and the fracture mode changes from quasi-cleavage fracture to dimple fracture. Compared with the base alloy, it is increased by 28%. It is the highest value of as-cast arc melting that has been reported so far. The maze-like eutectic of the high content of Nbss (54.9 ± 5.9%) phase promotes the formation of microcracks and inhibits the propagation of cracks in Nb-16Si-20Ti-1ZrC-0.5ZrB2 alloy.

Microstructure and mechanical properties of friction stir welding joint of in-situ ZrB2/AA7085 composites

Friction stir welding (FSW) has been widely used to join Al-Zn-Mg-Cu alloys. As the mechanical properties of the heat affected zone (HAZ) of Al-Zn-Mg-Cu alloys joints are affected by the additional welding thermal cycle, which always contributes to a weak HAZ. In this paper, the in-situ ZrB2 particle was used to optimize the mechanical properties of the HAZ of Al-Zn-Mg-Cu alloy joint. The effects of mass fraction of ZrB2 particle on the microstructure and tensile properties of in-situ ZrB2/AA7085 composites FSW joints were studied. The results showed that the coarsening of precipitates contributed to the softening of HAZ and declined the strength of AA7085 FSW joint to approximately 294.3 MPa. Small amount of in-situ ZrB2 (1 wt%) provided an additional strength of HAZ and increased the strength of the FSW joint to approximately 367.2 MPa. However, when the content of ZrB2 increased to 3 wt% and 5 wt%, many ZrB2-rich band structures were formed in stir zone. The brittle nature of the ZrB2-rich band structure resulted in the crack initiation and propagation in stir zone. It declined the strength of ZrB2 (3 wt% and 5 wt%)/AA7085 FSW joint to 308.3 MPa and 275.5 MPa, respectively.