To obtain high-performance Zr-based ultra-high-temperature composites,Zr-based ultra-high-temperature gradient composites were prepared by changing the laying method of the infiltrant via reactive melt infiltration.Th...To obtain high-performance Zr-based ultra-high-temperature composites,Zr-based ultra-high-temperature gradient composites were prepared by changing the laying method of the infiltrant via reactive melt infiltration.The effects of different infiltrant laying methods on the microstructure and ablative properties of Zr-based ultrahigh-temperature gradient composites were investigated.The results showed that the gradient structure of the Zr-based ultrahigh-temperature gradient composites differed when the composition ratio of the infiltrant was changed.When the thicknesses of the Zr/Mo/Si layers were 6/4/12 mm and 8/2/12 mm,the SiMoZrC solid solution content in the samples increased and decreased along the infiltration direction,respectively.The gradient samples were ablated in an oxyacetylene flame at 3000°C for 40 s.The ablation resistance of the sample was the highest when the infiltrant was a powder and the thickness of the Zr/Mo/Si layer was 6/4/12 mm.展开更多
C/C-ZrC-SiC composites with different ZrC-SiC contents were fabricated by precursor infiltration and pyrolysis. The effect of ceramic content on the microstructure and ablation resistance was investigated. Both the C/...C/C-ZrC-SiC composites with different ZrC-SiC contents were fabricated by precursor infiltration and pyrolysis. The effect of ceramic content on the microstructure and ablation resistance was investigated. Both the C/C-SiC and C/C-ZrC-SiC composites exhibited good ablation resistance under the plasma flame above 2300℃. Withtheincreaseof ZrC content, a continuous oxide layer and a solid Zr-Si-O mesophase were formed during the ablation. And the structure of the formed oxides layer closely linked with the contents of ZrC-SiC ceramics. The solid ZrO2-ZrC and Zr-Si-O mesophase could increase the viscosity of SiO2 moderately and improve the anti-scouring ability. The continuous SiO2-ZrO2-ZrC-SiC layer would serve as a thermal and oxygen barrier for preventing the substratefrom further ablation. The C/C-ZrC-SiC composites with 27.2%ZrC and 7.56%SiC shows superior ablation resistance, and the mass and linear ablation rates are-3.51 mg/s and-1.88 μm/s, respectively.展开更多
Ultrahigh-temperature ceramics were added to C/C composites to meet their application requirement in a high-temperature oxidizing environment. C/C-ZrB2-SiC composites were fabricated by high-solid-loading slurry impre...Ultrahigh-temperature ceramics were added to C/C composites to meet their application requirement in a high-temperature oxidizing environment. C/C-ZrB2-SiC composites were fabricated by high-solid-loading slurry impregnation with polymer infiltration and pyrolysis. The dispersion and rheological behavior of ZrB2 slurry and the microstructural, mechanical, and ablation properties of the C/C-ZrB2-SiC composites were investigated. Results indicated that a well-dispersed and low-viscosity ZrB2 slurry was obtained using 0.40 wt.% polyethyleneimine as a dispersant at pH 5. Ceramics were uniformly distributed in the short-cut fiber layer and needle-punched area. The flexural strength of the C/C-ZrB2-SiC composites was 309.30 MPa. The composites exhibited satisfactory ablation resistance under the oxyacetylene flame of 2500℃, and the mass and linear ablation rates were 0.40 mg/s and 0.91 μm/s, respectively. A continuous and compact Zr O2 layer, which could effectively reduce the diffusion rate of oxygen and protect the composites from being ablated, was formed.展开更多
The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite cons...The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite consists of dispersion of hollow cenosphere particles in a-Ti matrix. The average pore diameter varies from 50 to 150 μm. The presence of porosities is attributed to the damage of cenosphere particles due to the application of load during compaction as well as to the hollow nature of cenospheres. A detailed X-ray diffraction profile of the composites shows the presence of Al2O3, SiO2, TiO2 and α-Ti. The average microhardness of the composite （matrix） varies from HV 1100 to HV 1800 as compared with HV 240 of the as-received substrate. Wear studies show a significant enhancement in wear resistance against hardened steel ball and WC ball compared with that of commercially available Ti-6Al-4V alloy. The wear mechanism was established and presented in detail. The corrosion behavior of the composites in 3.56% NaCl （mass fraction） solution shows that corrosion potential （φcorr） shifts towards nobler direction with improvement in pitting corrosion resistance. However, corrosion rate of the cenosphere dispersed Ti matrix composite increases compared with that of the commercially available Ti-6Al-4V alloy.展开更多
An optimum design model has been proposed for carbon/carbon ablative property based on genetic algorithm,in which the optimum parameters are the number of woven satins,K of fiber bundles,layers per unit height,the ave...An optimum design model has been proposed for carbon/carbon ablative property based on genetic algorithm,in which the optimum parameters are the number of woven satins,K of fiber bundles,layers per unit height,the average distance of puncture fibers in Z direction and Ply Stacking angle,and the constraint conditions are the density and diameter of carbon fibers and the density of carbon matrix.The results demonstrate that after optimization,the overall height of the ablative carbon/carbon surface is reduced by 56.5%,the standard deviation is reduced by 34.9% and the surface roughness is reduced by 12.6%,which suggests the remarkable improvement of ablative homogeneity.The present investigation can provide practical methodology for the optimum design of carbon/carbon ablative property and the development of new carbon/carbon composites.展开更多
基金supported by the National Natural Science Foundation of China(No.U19A2099)the Open Fund for Hubei Provincial Key Laboratory of Advanced Aerospace Power Technology,China(No.DLJJ2103007)the Hunan Graduate Research Innovation Project,China(No.CX20220097)。
文摘To obtain high-performance Zr-based ultra-high-temperature composites,Zr-based ultra-high-temperature gradient composites were prepared by changing the laying method of the infiltrant via reactive melt infiltration.The effects of different infiltrant laying methods on the microstructure and ablative properties of Zr-based ultrahigh-temperature gradient composites were investigated.The results showed that the gradient structure of the Zr-based ultrahigh-temperature gradient composites differed when the composition ratio of the infiltrant was changed.When the thicknesses of the Zr/Mo/Si layers were 6/4/12 mm and 8/2/12 mm,the SiMoZrC solid solution content in the samples increased and decreased along the infiltration direction,respectively.The gradient samples were ablated in an oxyacetylene flame at 3000°C for 40 s.The ablation resistance of the sample was the highest when the infiltrant was a powder and the thickness of the Zr/Mo/Si layer was 6/4/12 mm.
基金Project(2011CB605801)supported by the National Basic Research Program of ChinaProject(51304249)supported by the National Natural Science Foundation of China+1 种基金Project(2013BAE04B02)supported by the National Key Technology Support Program of ChinaProject(14JJ3023)supported by the Hunan Provincial Science Foundation of China
文摘C/C-ZrC-SiC composites with different ZrC-SiC contents were fabricated by precursor infiltration and pyrolysis. The effect of ceramic content on the microstructure and ablation resistance was investigated. Both the C/C-SiC and C/C-ZrC-SiC composites exhibited good ablation resistance under the plasma flame above 2300℃. Withtheincreaseof ZrC content, a continuous oxide layer and a solid Zr-Si-O mesophase were formed during the ablation. And the structure of the formed oxides layer closely linked with the contents of ZrC-SiC ceramics. The solid ZrO2-ZrC and Zr-Si-O mesophase could increase the viscosity of SiO2 moderately and improve the anti-scouring ability. The continuous SiO2-ZrO2-ZrC-SiC layer would serve as a thermal and oxygen barrier for preventing the substratefrom further ablation. The C/C-ZrC-SiC composites with 27.2%ZrC and 7.56%SiC shows superior ablation resistance, and the mass and linear ablation rates are-3.51 mg/s and-1.88 μm/s, respectively.
基金Project(GFZX0101040101-2012C20X) supported by the National Basic Research Program of ChinaProject(2017JJ2320) supported by the Natural Science Foundation of Hunan Province,China
文摘Ultrahigh-temperature ceramics were added to C/C composites to meet their application requirement in a high-temperature oxidizing environment. C/C-ZrB2-SiC composites were fabricated by high-solid-loading slurry impregnation with polymer infiltration and pyrolysis. The dispersion and rheological behavior of ZrB2 slurry and the microstructural, mechanical, and ablation properties of the C/C-ZrB2-SiC composites were investigated. Results indicated that a well-dispersed and low-viscosity ZrB2 slurry was obtained using 0.40 wt.% polyethyleneimine as a dispersant at pH 5. Ceramics were uniformly distributed in the short-cut fiber layer and needle-punched area. The flexural strength of the C/C-ZrB2-SiC composites was 309.30 MPa. The composites exhibited satisfactory ablation resistance under the oxyacetylene flame of 2500℃, and the mass and linear ablation rates were 0.40 mg/s and 0.91 μm/s, respectively. A continuous and compact Zr O2 layer, which could effectively reduce the diffusion rate of oxygen and protect the composites from being ablated, was formed.
基金Financial supports from various funding agencies Tata Steel, Jamshedpur, Department of Science and Technology, New Delhi, Council of Scientific and Industrial Research, New Delhi and Board of Research on Nuclear Science, Bombay for the present study are gratefully acknowledged
文摘The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite consists of dispersion of hollow cenosphere particles in a-Ti matrix. The average pore diameter varies from 50 to 150 μm. The presence of porosities is attributed to the damage of cenosphere particles due to the application of load during compaction as well as to the hollow nature of cenospheres. A detailed X-ray diffraction profile of the composites shows the presence of Al2O3, SiO2, TiO2 and α-Ti. The average microhardness of the composite （matrix） varies from HV 1100 to HV 1800 as compared with HV 240 of the as-received substrate. Wear studies show a significant enhancement in wear resistance against hardened steel ball and WC ball compared with that of commercially available Ti-6Al-4V alloy. The wear mechanism was established and presented in detail. The corrosion behavior of the composites in 3.56% NaCl （mass fraction） solution shows that corrosion potential （φcorr） shifts towards nobler direction with improvement in pitting corrosion resistance. However, corrosion rate of the cenosphere dispersed Ti matrix composite increases compared with that of the commercially available Ti-6Al-4V alloy.
基金Sponsored by the National Natural Science Foundation of China(Grant No.1057244)
文摘An optimum design model has been proposed for carbon/carbon ablative property based on genetic algorithm,in which the optimum parameters are the number of woven satins,K of fiber bundles,layers per unit height,the average distance of puncture fibers in Z direction and Ply Stacking angle,and the constraint conditions are the density and diameter of carbon fibers and the density of carbon matrix.The results demonstrate that after optimization,the overall height of the ablative carbon/carbon surface is reduced by 56.5%,the standard deviation is reduced by 34.9% and the surface roughness is reduced by 12.6%,which suggests the remarkable improvement of ablative homogeneity.The present investigation can provide practical methodology for the optimum design of carbon/carbon ablative property and the development of new carbon/carbon composites.
