| 1. |
- Wang, Cao, et al.
(författare)
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Microstructure homogeneity control in spark plasma sintering of Al2O3 ceramics
- 2010
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Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 31:1-2, s. 231-235
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Tidskriftsartikel (refereegranskat)abstract
- Homogeneous microstructure control in the SPS (spark plasma sintering) sintered big size Al2O3 ceramic was realized by the synergy effect of grain boundary tailoring and proper pressure profile design. Two-step pressure profile itself did not show any efficient densification enhancement if no grain boundary modifier MgO added. The two-step pressure profile can effectively reduce average grain size and grain size difference over the sintered specimen, while MgO doping can reduce the average grain size in the whole sintered samples. Finally, a general strategy to overcome the intrinsic temperature gradient in SPS is suggested.
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| 2. |
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| 3. |
- Shen, Minhao, et al.
(författare)
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Effects of exposure time and printing angle on the curing characteristics and flexural strength of ceramic samples fabricated via digital light processing
- 2020
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 46:15, s. 24379-24384
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Tidskriftsartikel (refereegranskat)abstract
- The development of photosensitive slurries for additive manufacturing has attracted great interest due to their correlation with the final properties of the fabricated parts. This paper focus on the printing quality control in digital light processing (DLP) 3D printing of advanced ceramics. Systematic experiments were performed to assess the effects of the exposure time and printing angle on the three-point bending strength of the fabricated samples. The exposure time affected the bending strength of the printed zirconia ceramic dramatically. When the weak exposure time is 1 s and the strong exposure time is 13 s, the average bending strength can reach 580 MPa while Weibull modulus can reach 8.84. Meanwhile, the printing angle also affected the bending strength mechanical sample printed at 45 degrees exhibits the worst performance.
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| 4. |
- 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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| 5. |
- Wang, Cao, et al.
(författare)
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Transparent polycrystalline ruby ceramic by spark plasma sintering
- 2010
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Ingår i: Materials research bulletin. - : Elsevier BV. - 0025-5408 .- 1873-4227. ; 45:9, s. 1127-1131
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Tidskriftsartikel (refereegranskat)abstract
- Fine-grained and transparent polycrystalline ruby ceramics (Cr2O3-doped Al2O3) were successfully prepared by spark plasma sintering (SPS). The effect of Cr2O3 concentration on the grain size, hardness, fracture toughness and thermal conductivity of ruby ceramics was investigated systematically. For 0.05 wt.% Cr2O3, high in-line transmittance of 85% at 2000 nm can be reached, further increase of Cr2O3 concentration leads to the decrease in transmittance. High hardness of 23.95-25.05 GPa can be achieved due to the fine grain size in all ruby ceramics. The fracture toughness of 1.9-2.29 MPa m(1/2) indicates that no improvement in fracture toughness over pure Al2O3 can be obtained by Cr2O3 doping in these submicron grained ruby ceramics. High thermal conductivity of 28-29.8 W/(m K) at room temperature, close to that of single crystal sapphire, can be achieved. The change in grain size for different Cr2O3 concentrations is the major reason for the change in mechanical and thermal properties, but not for the change in optical properties.
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| 6. |
- Zhao, Weiming, et al.
(författare)
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Mechanical properties of zirconia octet truss structures fabricated by DLP 3D printing
- 2020
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Ingår i: Materials Research Express. - : IOP PUBLISHING LTD. - 2053-1591. ; 7:8
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Tidskriftsartikel (refereegranskat)abstract
- Zirconia ceramic octet-truss structures with various strut size and unit cell numbers were successfully fabricated through a DLP-based 3D printing method. The mechanical properties and energy absorption capacity under compressive load were investigated systematically. The sides of all cubes are 10 mm, the strut size was changed from 0.25 mm to 2 mm, cells number was in the range of 1(1 x 1 x 1)-125(5 x 5 x 5). It has been seen that the relative density, compressive strength and energy absorption increases with the increase of strut size when cell numbers remain the same. It can be concluded that the strength and energy absorption were affected by the relative density, strut size and the stacking mode of the unit cells. So far, with this study, a high compressive strength of 75.3 MPa and a reasonably good energy absorption of 6.76 x 10(5)J m(-3)can be achieved at a relative density of 48.57%.
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| 7. |
- 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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