| 1. |
- Nan, Beiya, et al.
(författare)
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Microstructure and Properties of Porous SiC Ceramics Modified by CVI-SiC Nanowires
- 2019
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Ingår i: Advanced Engineering Materials. - : Wiley. - 1438-1656 .- 1527-2648. ; 21:5
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Tidskriftsartikel (refereegranskat)abstract
- Sintered porous SiC ceramics are modified with SiC nanowires prepared via chemical vapor infiltration (CVI). SiC nanowires are successfully grown within sintered porous SiC ceramics following vapor-liquid-solid growth. The diameter of the SiC nanowires is in the range of 200 nm-1 mu m, and first decreases with increasing input gas ratio (alpha = 50, 60, 70, and 80) and increases thereafter. The diameter of the nanowires decreases from the surface to the interior areas of the porous SiC ceramics. SiC nanowires effectively improve the mechanical properties of the porous SiC ceramics, and sample Ni-50 has the highest flexural strength of 33.91 MPa and fracture toughness of 0.79 MPa center dot m(1/2), which increases by 90.4% and 49.1% compared to an unmodified sample, respectively. Additionally, the presence of SiC nanowires leads to porous SiC ceramics with altered porosity and microstructure, and higher thermal conductivity. The porous SiC ceramics modified by CVI SiC nanowires satisfy the requirements of gas filtration applications and the pressure drop increases with decreasing apparent porosity. The porous SiC ceramics modified with CVI SiC nanowire has higher permeability than those resulting from the introduction of CVI-SiC matrix or CVD-SiC coating into porous SiC ceramics.
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| 2. |
- Wang, Cao, et al.
(författare)
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FEM analysis of the temperature and stress distribution in spark plasma sintering : Modelling and experimental validation
- 2010
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Ingår i: Computational materials science. - : Elsevier. - 0927-0256 .- 1879-0801. ; 49:2, s. 351-362
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Tidskriftsartikel (refereegranskat)abstract
- A fully thermal-electrical-mechanical coupled and dynamic finite element model (FEM) is implemented to analyze of the temperature and stress distribution in spark plasma sintering (SPS) process. The real densification behaviour is also integrated by the moving mesh technique. The simulation studies were conducted using COMSOL and a range of die sizes, heating rates and uniaxial stresses were considered. The further validation experiments are implemented to validate the simulation results. The detailed microstructure investigations generally demonstrate that the temperature and stress profile obtained in present model are correct. But further development of complicated models is still needed for more precise prediction of sintering condition and microstructure development in SPS.
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| 3. |
- You, Qiangwei, et al.
(författare)
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Microstructure and properties of porous SiC ceramics by LPCVI technique regulation
- 2017
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 43:15, s. 11855-11863
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Tidskriftsartikel (refereegranskat)abstract
- A new gradient pore structure in porous SiC ceramics was fabricated by low pressure chemical vapor infiltration (LPCVI). Effects of deposition duration on the mechanical properties and permeability of porous SiC ceramics were investigated. Results demonstrated that pore diameter and shapes decreased from the surface to the interior along with LPCVI duration. Porous SiC ceramics with deposition duration of 160 h exhibited flexural strength of 48.05 MPa and fracture toughness of 1.30 MPa m(1/2), where 221% and 189% improvements were obtained compared to porous SiC ceramics without LPCVI, due to CVI-SiC layer strengthening effect. Additionally, at the same gas velocity, pressure drop increase rate was faster due to apparent porosity and pore size change.
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| 4. |
- Zhao, Zhe, et al.
(författare)
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Finite element modelling of temperature distribution in spark plasma sintering
- 2010
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Ingår i: Key Engineering Materials. - 1013-9826 .- 1662-9795. ; 434-435, s. 808-813
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Tidskriftsartikel (refereegranskat)abstract
- A finite element model (FEM) is developed to simulate the temperature distribution in the sample/die/punch assembly during the spark plasma sintering (SPS) process. A thermal–electrical coupled model with temperature dependent thermal and electrical properties is implemented. The simulation studies were conducted using COMSOL and a range of heating-rates and die sizes were considered. Also, both temporary and equilibrium condition during heating process were evaluated in order to express the real temperature development in the sintering. During the spark plasma sintering process, the temperature difference between the sample center and the die surface depend on the heating-rate and die size. The simulation results also revealed that the temperature gradient during the heating process is much bigger than that in the dwelling period. It is necessary to consider the temporary state during the spark plasma sintering process in order to guarantee a well–controlled microstructure, especially in non-conductive ceramic materials.
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