Effect of HfB2 on microstructure and mechanical properties of ZrB2–SiC-based composites

Balak, Zohre; Zakeri, M.

doi:10.1016/j.ijrmhm.2015.07.011

Cited by 61 publications

(12 citation statements)

References 16 publications

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“…The porosity observed in HZ20S (Figure 5c) decreases with CNT reinforcement (Figure 5d) from~4% to~0.5% (see Figure 5e) is due to the ability of CNT to fill the gap and occupy pores [38]. It can also be anticipated that HfB 2 has a negative effect on the densification of ZrB 2 -SiC composites, which is similar to the results obtained by Balak et al [23]. The structure of the CNT is evident from the image shown in Figure 5f, and similar to SiC, CNT also sits at the intergranular regions of the HfB 2 -ZrB 2 system.…”

Section: Microstructural Analysis Of Hfb 2 -Zrb 2 -Sic-cnt Compositessupporting

confidence: 86%

“…The addition of SiC in HfB 2 and ZrB 2 has led to nearly full densification (100% for H20S,~99% for Z20S) is attributed to the high thermal conductivity of SiC and its ability to sit near the grain boundary which aids densification, allowing the sintering to be faster and at lower temperatures [7,12]. The densification was found to decrease in HZ20S (from ≤1% in H20S and Z20S to~4% in HZ20S, see Table 1) is commensurate with recent report in literature [23] which shows that the addition of HfB 2 in ZrB 2 increases porosity due to the occurrence of chemical reaction between them. On the other hand, further addition of CNT (i.e., HZ20S6C), increases the densification to~99.5% which is attributed to the high thermal conductivity of CNT [12,32].…”

Section: Densification Of Hfb 2 -Zrb 2 -Sic-cnt Compositesmentioning

confidence: 71%

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Phase and Microstructural Correlation of Spark Plasma Sintered HfB2-ZrB2 Based Ultra-High Temperature Ceramic Composites

Nisar

Balani

2017

Coatings

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Abstract:The refractory diborides (HfB 2 and ZrB 2 ) are considered as promising ultra-high temperature ceramic (UHTCs) where low damage tolerance limits their application for the thermal protection system in re-entry vehicles. In this regard, SiC and CNT have been synergistically added as the sintering aids and toughening agents in the spark plasma sintered (SPS) HfB 2 -ZrB 2 system. Herein, a novel equimolar composition of HfB 2 and ZrB 2 has shown to form a solid-solution which then allows compositional tailoring of mechanical properties (such as hardness, elastic modulus, and fracture toughness). The hardness of the processed composite is higher than the individual phase hardness up to 1.5 times, insinuating the synergy of SiC and CNT reinforcement in HfB 2 -ZrB 2 composites. The enhanced fracture toughness of CNT reinforced composite (up to a 196% increment) surpassing that of the parent materials (ZrB 2 /HfB 2 -SiC) is attributed to the synergy of solid solution formation and enhanced densification (~99.5%). In addition, the reduction in the analytically quantified interfacial residual tensile stress with SiC and CNT reinforcements contribute to the enhancement in the fracture toughness of HfB 2 -ZrB 2 -SiC-CNT composites, mandatory for aerospace applications.

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Section: Microstructural Analysis Of Hfb 2 -Zrb 2 -Sic-cnt Compositessupporting

confidence: 86%

Section: Densification Of Hfb 2 -Zrb 2 -Sic-cnt Compositesmentioning

confidence: 71%

Phase and Microstructural Correlation of Spark Plasma Sintered HfB2-ZrB2 Based Ultra-High Temperature Ceramic Composites

Nisar

Balani

2017

Coatings

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“…Among UHTCs, borides of transition metals (TMBs) such as ZrB2 and HfB2 present unique combinations of mechanical, physical and chemical properties, such as high melting points (>3000°C), high electrical and thermal conductivities, chemical inertness as well as favorable thermal shock resistance. Therefore, although transition metal carbides (TMCs) commonly show higher melting points, TMBs seem to be promising candidates for high-temperature thermomechanical and structural applications [4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…Among several sintering additives, it has been revealed that HfB2 (melting point: 3380°C) as another member of HUTCs family, not only improves the mechanical properties and thermal shock resistance of ZrB2-SiC composites, but also can influence the oxidation behavior of the composite, as it forms a protective oxide layer, HfO2 [5,[7][8][9]. Anyway, to the best of our understanding, there is no comprehensive report on the effects of HfB2 on oxidation resistance of ZrB2-SiC composites.…”

Section: Introductionmentioning

confidence: 99%

HfB2-doped ZrB2-30 vol.% SiC composites: Oxidation resistance behavior

Dodi

Balak

2020

Preprint

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In order to investigate the HfB2 on microstructure and oxidation resistance of ZrB2-30 vol% SiC, ZrB2-30 vol% SiC composites with different amount of HfB2 (4, 8 and 12 vol%) were SPSed. Microstructural evaluations were done by scanning electron microscopic (SEM). In order to investigate the oxidation resistance, the samples were placed in box furnace at the temperature of 1400 C for different times. The samples were weighted before and after the oxidation and the 𝛥w was applied as criterion of oxidation. Thickness of SiO2 layer and Si depleted layer were also used as oxidation criterion. The results showed that HfB2 addition, caused to decrease 𝛥w and better oxidation resistance.

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“…HfB 2 and HfN have high hardness, high melting point, and high oxidation resistance, and as reinforcements they can enhance the mechanical properties of ceramics such as ZrB 2 -CrSi 2 -HfB 2 , ZrB 2 -SiC-HfB 2 , B 4 C-HfB 2 , and SiBCN-HfN [17,18,19,20], which make them potential candidate reinforcements for ceramic tool materials. In addition, because HfB 2 and HfN have better thermal stability to resist deformation and decomposition at elevated temperature, they may improve the cutting performance and working life of TiB 2 -based ceramic tools.…”

Section: Introductionmentioning

confidence: 99%

Effects of HfB2 and HfN Additions on the Microstructures and Mechanical Properties of TiB2-Based Ceramic Tool Materials

Song

Liang

et al. 2017

Materials

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The effects of HfB2 and HfN additions on the microstructures and mechanical properties of TiB2-based ceramic tool materials were investigated. The results showed that the HfB2 additive not only can inhibit the TiB2 grain growth but can also change the morphology of some TiB2 grains from bigger polygons to smaller polygons or longer ovals that are advantageous for forming a relatively fine microstructure, and that the HfN additive had a tendency toward agglomeration. The improvement of flexural strength and Vickers hardness of the TiB2-HfB2 ceramics was due to the relatively fine microstructure; the decrease of fracture toughness was ascribed to the formation of a weaker grain boundary strength due to the brittle rim phase and the poor wettability between HfB2 and Ni. The decrease of the flexural strength and Vickers hardness of the TiB2-HfN ceramics was due to the increase of defects such as TiB2 coarse grains and HfN agglomeration; the enhancement of fracture toughness was mainly attributed to the decrease of the pore number and the increase of the rim phase and TiB2 coarse grains. The toughening mechanisms of TiB2-HfB2 ceramics mainly included crack bridging and transgranular fracture, while the toughening mechanisms of TiB2-HfN ceramics mainly included crack deflection, crack bridging, transgranular fracture, and the core-rim structure.

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Effect of HfB2 on microstructure and mechanical properties of ZrB2–SiC-based composites

Cited by 61 publications

References 16 publications

Phase and Microstructural Correlation of Spark Plasma Sintered HfB2-ZrB2 Based Ultra-High Temperature Ceramic Composites

Phase and Microstructural Correlation of Spark Plasma Sintered HfB2-ZrB2 Based Ultra-High Temperature Ceramic Composites

HfB2-doped ZrB2-30 vol.% SiC composites: Oxidation resistance behavior

Effects of HfB2 and HfN Additions on the Microstructures and Mechanical Properties of TiB2-Based Ceramic Tool Materials

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