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Shaobai Sang - One of the best experts on this subject based on the ideXlab platform.
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heightening mechanical properties and Thermal Shock Resistance of low carbon magnesia graphite refractories through the catalytic formation of nanocarbons and ceramic bonding phases
Journal of Alloys and Compounds, 2019Co-Authors: Tianbin Zhu, Shaobai SangAbstract:Abstract The in-situ catalytic formation of nanocarbons and ceramic bonding phases in low–carbon magnesia–graphite refractories is one of the significant strategies for heightening their mechanical properties and Thermal Shock Resistance. Here, effect of aluminum content and nickel–containing catalyst addition on microstructural evolution, mechanical and thermo-mechanical behavior of such refractories was explored. Under the function of the catalyst, addition of aluminum powders allowed the newly growth of plenty of nanocarbons (e.g., carbon nanotubes and carbon onions), and also accelerated the in–situ formation of more ceramic bonding phases (e.g., magnesia whiskers and spinel whiskers/particles, etc.) in samples. This occurrence optimized significantly the microstructure of samples, correspondingly giving rise to their superior mechanical properties and Thermal Shock Resistance. This work might provide a path for exploring low–carbon magnesia–graphite refractories with high performances.
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enhanced Thermal Shock Resistance of low carbon al2o3 c refractories with direct cvd synthesis of nano carbon decorated oxides
Journal of The European Ceramic Society, 2018Co-Authors: Jiangbo Shan, Shaobai Sang, Ning Liao, Dechang JiaAbstract:Abstract Novel low carbon Al2O3-C refractories were prepared through adopting chemical vapour deposition (CVD) synthesized nano carbon decorated Al2O3 powder. The phase compositions, microstructures, mechanical properties and Thermal Shock Resistance of Al2O3-C refractories were characterized and evaluated. The results show that the morphologies of nano carbon composites are mainly dominated by the concentration of catalyst. Specifically, the growth of MWCNTs is preferred with a Ni2+ concentration at 0.1 mol/L, while higher concentrations e.g. 0.3 mol/L would stimulate the formation of nano-onion like carbon. With the introduction of nano carbon decorated Al2O3 additives, the residual strength after Thermal Shock can reach 12.4 MPa, which is much higher than the 2 wt% nano carbon black containing specimens (6.4 MPa). The enhanced Thermal Shock Resistance should be attributed to that the nano onion-like carbon reduces the cohesion between the matrix and the Al2O3 particles and decreases the Thermal expansion coefficient.
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a new approach to fabricate mgo c refractories with high Thermal Shock Resistance by adding artificial graphite
Journal of The European Ceramic Society, 2017Co-Authors: Yawei Li, Shaobai SangAbstract:Abstract To lower the carbon content but to exhibit a better Thermal Shock Resistance with MgO-C refractories containing 14 wt% flaky graphite, a new approach, based on the addition of artificial graphite, is reported for enhancing the Thermal Shock Resistance of such refractories with 10 wt% graphite in the present work. The addition of artificial graphite (not more than 2 wt%) has a slight influence on the flexural strength of the specimens, but apparently enhances their Thermal Shock Resistance. In particular, the specimen containing 2 wt% artificial graphite has a higher flexural strength after Thermal Shocks and a relatively closer residual strength ratio as compared to the reference specimen with 14 wt% flaky graphite, as it is related with the formation of more AlN reinforced phases, decreased coefficient of Thermal expansion as well as increased work of fracture.
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improved Thermal Shock Resistance of magnesia graphite refractories by the addition of mgo c pellets
Materials & Design, 2017Co-Authors: Shaobai Sang, Tianbin Zhu, Zhipeng XieAbstract:Abstract Magnesia-graphite (MgO-C) refractories with 12–20 wt% carbon contents are extensively used for the taphole sleeve bricks, bottom blowing elements, slag line bricks, etc. in steelmaking operations. To reduce the carbon content but to have the same or even superior Thermal Shock Resistance with commercial available material compositions (14 wt% flaky graphite), we report here a new approach based on the granulating treatment of flaky graphite to improve the Thermal Shock Resistance of MgO-C refractories (10 wt% flaky graphite). MgO-C pellets are firstly prepared by the crushing granulation method, and then introduced into such refractories. Addition of MgO-C pellets has no apparent influence on their flexural strength, but enhances their flexural strength after Thermal Shocks and residual strength ratio. Particularly, when 10 wt% flaky graphite of the specimens is replaced totally by MgO-C pellets, their Thermal Shock Resistance is superior to that of the specimens containing 14 wt% flaky graphite. This new method opens up possibilities to obtain MgO-C refractories with improved Thermal Shock Resistance.
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mechanical behavior and Thermal Shock Resistance of mgo c refractories influence of graphite content
Ceramics International, 2017Co-Authors: Shaobai Sang, Tianbin Zhu, Zhipeng XieAbstract:Abstract The mechanical and thermo-mechanical properties of MgO-C refractories are of major importance in the industrial applications, and highly depend on the optimization of their microstructural design. In the present work, the influence of flaky graphite content on mechanical behavior and Thermal Shock Resistance of such refractories was investigated with the aid of the wedge splitting test, fractal and microscopic fractographic analysis. The results showed that the increase of graphite content in the specimens led to an enhanced non-linear fracture behavior, a reduced nominal notch tensile strength (σ NT ), and a higher specific fracture energy (G f ), characteristic length ( l ch ) and Thermal Shock Resistance parameter (R st ). The fractal analysis of the crack propagation path of the specimens after the wedge splitting test indicated that increasing graphite content in the refractories can enhance their irregularity of the crack propagation path during fracture. Also, it was suggested from microscopic fractographic analysis that the improvement of Thermal Shock Resistance of MgO-C refractories was positively correlated with the increase of interface crack propagation.
Zhi Wang - One of the best experts on this subject based on the ideXlab platform.
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effect of surface oxidation on Thermal Shock Resistance of zrb2 sic zrc ceramic at temperature difference from 800 to 1900 c
Corrosion Science, 2015Co-Authors: Zhi Wang, Peng ZhouAbstract:Abstract In the present work, the ZrB2–ZrC–SiC ceramic was fabricated at 1900 °C through the reaction (5Zr + 2B4C + Si → 4ZrB2 + ZrC + SiC). The effect of oxidation behavior on the Thermal Shock Resistance of the ZrB2–ZrC–SiC ceramic was investigated in two kinds of heat conditions (air and vacuum) by measuring the residual strength after water quenching for the temperature difference ranging from 200 to 1900 °C. The improvement of Thermal Shock Resistance was attributed to the formation of oxide layers. The results of the present work indicate that the short-term oxidation is favorable to improve the Thermal Shock Resistance of ZrB2-based ceramics.
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effect of surface oxidation on Thermal Shock Resistance of the zrb2 sic zrc ceramic
Composites Science and Technology, 2011Co-Authors: Zhi Wang, Guodong Shi, Jin ShengAbstract:Abstract The isoThermal oxidation of the ZrB2–SiC–ZrC ceramic was carried out in static air at a constant temperature of 1000 ± 15 °C, 1200 ± 15 °C and 1400 ± 15 °C for 30 min, respectively. Compared with the original strength of 580 MPa, the strength for the specimen oxidized at 1000 °C, 1200 °C and 1400 °C for 30 min increased to 609 MPa, 656 MPa and 660 MPa, respectively, because the flaws in the surface of the specimen were sealed by the oxide layer. The Thermal Shock Resistance of the specimens before and after the oxidation was measured by the water quenching. The measured ΔTcrit for the specimen oxidized at 1000 °C, 1200 °C and 1400 °C were 352 °C, 453 °C and 623 °C, respectively, which was obviously higher than 270 °C for the unoxidized specimen. The improvement in the Thermal Shock Resistance was attributed to the formation the oxide layer on the surface of the specimen. The results here pointed to a promising method for improving strength and Thermal Shock Resistance of ZrB2-based ceramics.
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microstructure mechanical properties and Thermal Shock Resistance of zirconium diboride containing silicon carbide ceramic toughened by carbon black
Materials Chemistry and Physics, 2010Co-Authors: Shanbao Zhou, Zhi Wang, Xin Sun, Jiecai HanAbstract:Abstract ZrB2–20 vol.%SiC ultrahigh temperature ceramic containing 5 vol.% carbon black of nanometer size (ZSC) was prepared by hot-pressing at 1900 °C. The effect of carbon black addition on the microstructure and mechanical properties was investigated. Compared to the ZrB2–SiC ceramics, the fracture toughness was significantly improved whereas flexural strength and hardness of the ZSC ceramic were slightly degraded. The fracture toughness as high as 6.6 ± 0.5 MPa m1/2 was much higher than that of monolithic ZrB2 (2.3–3.5 MPa m1/2) and ZrB2–SiC ceramics (4.0–4.5 MPa m1/2). The toughening mechanisms were the crack deflection, bridging and branching. Furthermore, the effect of carbon black addition on the Thermal Shock Resistance was systematically investigated and discussed.
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effect of surface oxidation on Thermal Shock Resistance of zrb2 sic g composite
International Journal of Refractory Metals & Hard Materials, 2010Co-Authors: Zhi Wang, Xin SunAbstract:Abstract The Thermal Shock Resistance of a ZrB 2 –SiC composite containing flaky graphite was investigated in two different atmospheres – air and vacuum by measuring the retention of the flexural strength after water quenching for the temperature difference ranging from 200 up to 1900 °C. The residual strength values for the samples heated in vacuum gradually decreased with increasing temperature difference. When the temperature difference was above 1200 °C, the individual sample failed upon quenching. In contrast to the samples heated in vacuum, the residual strength values for the samples heated in air increased gradually as the temperature difference increased from 1200 up to 1700 °C; and the residual strength values again decreased for the temperature difference ranging from 1700 up to 1900 °C. These results indicated that the surface oxidation played the positive role in the Thermal Shock Resistance of the ZrB 2 –SiC–G composite.
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mechanical properties and Thermal Shock Resistance of zrb2 sic ceramic toughened with graphite flake and sic whiskers
Scripta Materialia, 2009Co-Authors: Xi Zhang, Zhi Wang, Changqing HongAbstract:ZrB 2 –20 vol.% SiC ceramic containing 10 vol.% graphite flake and 10 vol.% SiC whiskers (ZSGS) was fabricated by hot pressing. The mechanical properties and Thermal Shock Resistance of the ZSGS ceramic were investigated. The results revealed that Thermal Shock Resistance and fracture toughness were significantly improved, whereas slight degradation was attained in the flexural strength of the ZSGS ceramic. Furthermore, the effect of the Thermal conductivity, toughness and strength on the Thermal Shock Resistance of the ZSGS ceramic was also investigated and discussed.
Lei Zhuang - One of the best experts on this subject based on the ideXlab platform.
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improved Thermal Shock Resistance of sicnw pyc core shell structure toughened cvd sic coating
Journal of The European Ceramic Society, 2018Co-Authors: Lei ZhuangAbstract:Abstract In-situ SiC nanowire (SiCnw)/pyrolytic carbon (PyC) core-shell structures were introduced to mainly improve the Thermal Shock performance of chemical vapor deposition (CVD)-SiC coating on carbon/carbon (C/C) composites. The microstructure, phase composition, and mechanical properties of the CVD-SiC coating toughened by SiCnw/PyC core-shell structures were studied as well. The results show that the introduction of SiCnw/PyC core-shell structures can effectively alleviate the mismatch of coefficient of Thermal expansion (CTE) between SiC coating and C/C substrate, thus enhancing the Thermal Shock Resistance of the coating. Furthermore, the increased numbers of interfaces in the SiC coating owing to the addition of core-shell structures are beneficial to the mechanical properties of the coating after Thermal Shock test.
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effect of carbon nanotubes on the toughness bonding strength and Thermal Shock Resistance of sic coating for c c zrc sic composites
Journal of Alloys and Compounds, 2015Co-Authors: Qiangang Fu, Lei Zhuang, Hejun Li, Lei Feng, Junyi JingAbstract:Abstract In order to improve the toughness, interface bonding strength and Thermal Shock Resistance of SiC coating for C/C–ZrC–SiC composites, carbon nanotubes (CNTs) were prepared by injection chemical vapor deposition and attempted as the reinforcement materials in the SiC coating. After incorporating CNTs, the hardness and elastic modulus of the SiC coating increased by 26.37% and 28.23%, respectively. The interface bonding strength between SiC coating and C/C–ZrC–SiC composites was enhanced by 53.31%. The mass loss of the SiC coated C/C–ZrC–SiC composites after Thermal Shock between 1773 K and room temperature for 15 times decreased from 5.98% to 1.98%. The incorporation of CNTs can effectively improve the toughness, interface bonding strength and Thermal Shock Resistance of SiC coating due to the nanoscale toughening mechanism of CNTs by pullout, bridging and crack deflection.
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carbon nanotube toughened interlocking buffer layer to improve the adhesion strength and Thermal Shock Resistance of sic coating for c c zrc sic composites
Journal of Materiomics, 2015Co-Authors: Lei Zhuang, Lei Feng, Yonga GuoAbstract:Abstract For the purpose of improving the interface adhesion strength and Thermal Shock Resistance of SiC coating for C/C–ZrC–SiC composites, a carbon nanotube (CNT)-toughened interlocking buffer layer was constructed between the SiC coating and C/C–ZrC–SiC substrates by pre-oxidation and chemical vapor deposition. After incorporating CNTs, the fracture toughness of the buffer layer increased by 55.7%. The interface adhesion strength between SiC coating and C/C–ZrC–SiC composites was up to 6.8 N, which was 195.7% higher than that of the SiC coated specimens without CNT-toughened interlocking buffer layer. After 25-time Thermal Shock cycling between 1773 K and room temperature, the mass loss of the coated specimens decreased by 64.4%. The significant enhancement of interface bonding strength and Thermal Shock Resistance of SiC coating was mainly due to the simultaneous existence of micron scale “pinning effect” of the inlaid SiC coating and nanoscale toughing mechanism of CNTs.
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effect of pre oxidation treatment on the bonding strength and Thermal Shock Resistance of sic coating for c c zrc sic composites
Ceramics International, 2015Co-Authors: Lei Zhuang, Jiaping Zhang, Yongan Guo, Yucai ShanAbstract:Abstract To improve the bonding strength and Thermal Shock Resistance of SiC coating for C/C–ZrC–SiC composites, a transition layer with mechanical interlocking structure was constructed at the interface by pre-oxidation treatment and chemical vapor deposition. For the coated specimens with pre-oxidation treatment at 1073 K for 5 min, the bonding strength increased from 2.0 to 4.0 N, and the mass loss percentage decreased by 52.5% after 12-time Thermal cycling between 1773 K and room temperature in air. The transition interlocking structure can effectively alleviate the mismatch between the coefficients of Thermal expansion of SiC coating and C/C–ZrC–SiC substrate, improving the bonding strength and Thermal Shock Resistance. As the pre-oxidation time increases, a rugged and loose ZrO 2 –SiO 2 layer will be formed at the interface, which is disadvantageous to the bonding strength and Thermal Shock Resistance of SiC coating for C/C–ZrC–SiC composites, and results in the debonding and collapse of the coating.
Tianbin Zhu - One of the best experts on this subject based on the ideXlab platform.
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heightening mechanical properties and Thermal Shock Resistance of low carbon magnesia graphite refractories through the catalytic formation of nanocarbons and ceramic bonding phases
Journal of Alloys and Compounds, 2019Co-Authors: Tianbin Zhu, Shaobai SangAbstract:Abstract The in-situ catalytic formation of nanocarbons and ceramic bonding phases in low–carbon magnesia–graphite refractories is one of the significant strategies for heightening their mechanical properties and Thermal Shock Resistance. Here, effect of aluminum content and nickel–containing catalyst addition on microstructural evolution, mechanical and thermo-mechanical behavior of such refractories was explored. Under the function of the catalyst, addition of aluminum powders allowed the newly growth of plenty of nanocarbons (e.g., carbon nanotubes and carbon onions), and also accelerated the in–situ formation of more ceramic bonding phases (e.g., magnesia whiskers and spinel whiskers/particles, etc.) in samples. This occurrence optimized significantly the microstructure of samples, correspondingly giving rise to their superior mechanical properties and Thermal Shock Resistance. This work might provide a path for exploring low–carbon magnesia–graphite refractories with high performances.
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improved Thermal Shock Resistance of magnesia graphite refractories by the addition of mgo c pellets
Materials & Design, 2017Co-Authors: Shaobai Sang, Tianbin Zhu, Zhipeng XieAbstract:Abstract Magnesia-graphite (MgO-C) refractories with 12–20 wt% carbon contents are extensively used for the taphole sleeve bricks, bottom blowing elements, slag line bricks, etc. in steelmaking operations. To reduce the carbon content but to have the same or even superior Thermal Shock Resistance with commercial available material compositions (14 wt% flaky graphite), we report here a new approach based on the granulating treatment of flaky graphite to improve the Thermal Shock Resistance of MgO-C refractories (10 wt% flaky graphite). MgO-C pellets are firstly prepared by the crushing granulation method, and then introduced into such refractories. Addition of MgO-C pellets has no apparent influence on their flexural strength, but enhances their flexural strength after Thermal Shocks and residual strength ratio. Particularly, when 10 wt% flaky graphite of the specimens is replaced totally by MgO-C pellets, their Thermal Shock Resistance is superior to that of the specimens containing 14 wt% flaky graphite. This new method opens up possibilities to obtain MgO-C refractories with improved Thermal Shock Resistance.
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mechanical behavior and Thermal Shock Resistance of mgo c refractories influence of graphite content
Ceramics International, 2017Co-Authors: Shaobai Sang, Tianbin Zhu, Zhipeng XieAbstract:Abstract The mechanical and thermo-mechanical properties of MgO-C refractories are of major importance in the industrial applications, and highly depend on the optimization of their microstructural design. In the present work, the influence of flaky graphite content on mechanical behavior and Thermal Shock Resistance of such refractories was investigated with the aid of the wedge splitting test, fractal and microscopic fractographic analysis. The results showed that the increase of graphite content in the specimens led to an enhanced non-linear fracture behavior, a reduced nominal notch tensile strength (σ NT ), and a higher specific fracture energy (G f ), characteristic length ( l ch ) and Thermal Shock Resistance parameter (R st ). The fractal analysis of the crack propagation path of the specimens after the wedge splitting test indicated that increasing graphite content in the refractories can enhance their irregularity of the crack propagation path during fracture. Also, it was suggested from microscopic fractographic analysis that the improvement of Thermal Shock Resistance of MgO-C refractories was positively correlated with the increase of interface crack propagation.
Rui Zhang - One of the best experts on this subject based on the ideXlab platform.
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the influence of additive and temperature on Thermal Shock Resistance of zrb2 based composites fabricated by spark plasma sintering
Materials Chemistry and Physics, 2020Co-Authors: Xiaotong Zhao, Zhibo Chen, Hailong Wang, Zheng Zhang, Gang Shao, Rui Zhang, Bingbing Fan, Deliang ChenAbstract:Abstract ZrB2–SiC ceramics have become popular candidates as ultra-high temperature structural materials in recent years; however, their poor sinterability and poor Thermal Shock Resistance has limited their application. In this paper, high density ZrB2–SiC–Al3BC3 ultra-high temperature ceramics were successfully fabricated via the Spark Plasma Sintering(SPS) process using Al, B4C, and carbon powders as sintering additives. The Thermal Shock Resistance of the sintered ZrB2–SiC–Al3BC3 ceramics was estimated via the water quenching method and the flexural strength of the quenched specimens were determined. The critical Thermal Shock temperature of the sintered ZrB2–SiC–Al3BC3 ceramics increased with rising sintering temperature. The fracture toughness and flexural strength of the sample sintered at 1800 °C were improved to 748.27 ± 77.35 MPa and 6.15 ± 0.01 MPa m1/2, respectively. This sample showed excellent Thermal Shock Resistance behavior, with a critical Thermal Shock temperature of 592 °C. The improvement of the Thermal Shock Resistance was attributed to its higher fracture toughness and the distribution of rod-like grains.
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preparation of corundum mullite refractories with lightweight high strength and high Thermal Shock Resistance
Materialia, 2019Co-Authors: Yongqiang Chen, Bingbing Fan, Guoqi Liu, Rui ZhangAbstract:Abstract The influences of PMMA sphere, hollow SiO2 sphere, hollow corundum sphere and AlF3·3H2O on properties of corundum-mullite refractories have been investigated. The finite-element analysis was used to simulate Thermal stress of the samples in the process of Thermal Shock. The PMMA, hollow SiO2 and hollow corundum were used to form different pore structures. The AlF3·3H2O was used as a reaction medium to promote the mullite whiskers formation. F2 was formed by oxidation reaction between AlF3 and O2 which could react with edges of fused mullite aggregate besides corundum and silica. SEM results showed that much mullite whiskers formed in the contact area of matrix powder and fused mullite aggregate. Bridging mullite whiskers of in-situ formation between matrix and aggregates strongly improved strength performance and Thermal Shock Resistance of corundum-mullite materials. The closed pores from hollow corundum sphere were beneficial to Thermal Shock Resistance. The high open porosity after PMMA burning out is adverse to in-situ formation of mullite whisker. Hollow corundum sphere, AlF3·3H2O and suitable grain composition worked together providing corundum-mullite refractories of lightweight, high strength and high Thermal Shock Resistance.
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preparation of corundum mullite refractories with lightweight high strength and high Thermal Shock Resistance
Social Science Research Network, 2019Co-Authors: Yongqiang Chen, Bingbing Fan, Guoqi Liu, Rui ZhangAbstract:The influences of PMMA sphere, hollow SiO2 sphere, hollow corundum sphere and AlF3.3H2O on properties of corundum-mullite refractories have been investigated. The finite-element analysis was used to simulate Thermal stress of the samples in the process of Thermal Shock. The The PMMA, hollow SiO2 and hollow corundum were used to form different pore structures. The AlF3.3H2O was used as a reaction medium to promote the mullite whiskers formation. F2 was formed by oxidation reaction between AlF3 and O2 which could react with edges of fused mullite aggregate besides corundum and silica. SEM results showed that much mullite whiskers formed in the contact area of matrix powder and fused mullite aggregate. Bridging mullite whiskers of in-situ formation between matrix and aggregates strongly improved strength performance and Thermal Shock Resistance of corundum-mullite materials. The closed pores from hollow corundum sphere were beneficial to Thermal Shock Resistance. The high open porosity after PMMA burning out is adverse to in-situ formation of mullite whisker. Hollow corundum sphere, AlF3.3H2O and suitable grain composition worked together providing corundum-mullite refractories of lightweight, high strength and high Thermal Shock Resistance.