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排序方式: 共有609条查询结果,搜索用时 15 毫秒
1.
Chenglai Xin Rong Yuan Jiang Wu Qingyuan Wang Yanan Zhou 《Ceramics International》2021,47(3):3411-3420
A novel method for fabricating a nano-Cu/Si3N4 ceramic substrate is proposed. The nano-Cu/Si3N4 ceramic substrate is first fabricated using spark plasma sintering (SPS) with the addition of nanoscale multilayer films (Ti/TiN/Ti/TiN/Ti) as transition layers. The microstructures of the nano-Cu metal layer and the interface between Cu and Si3N4 are investigated. The results show that a higher SPS temperature increases the grain size of the nano-Cu metal layer and affects the hardness. The microstructure of the transition layer evolves significantly after SPS. Ti in the transition layer can react with Si3N4 and with nano-Cu to form interfacial reaction layers of TiN and Ti–Cu, respectively; these ensure stronger bonding between nano-Cu and Si3N4. Higher SPS temperatures improve the diffusion ability of Ti and Cu, inducing the formation of Ti3Cu3O compounds in the nano-Cu metal layer and Ti2Cu in the transition layer. This study provides an important strategy for designing and constructing a new type of ceramic substrate. 相似文献
2.
《Journal of the European Ceramic Society》2022,42(13):6056-6066
We analysed with different methods the densification of UO2 nanopowders in SPS under constant heating rate (CHR) and isothermal sintering conditions. The apparent activation energy of densification in SPS (75 kJ/mol with CHR method) is significantly smaller than in conventional sintering. It is shown that this is likely not an effect of the applied current. We also observed a threshold stress at 64 MPa for the transition from pressure-insensitive sintering (stress exponent n≈0) to pressure-assisted sintering, suggesting that the contribution of the capillary stresses in such nanopowders is comparable with the typical stress applied in SPS. 相似文献
3.
Víctor Carnicer M José Orts Rodrigo Moreno Enrique Sánchez 《Ceramics International》2018,44(11):12014-12020
In this research, Suspension Plasma Spraying (SPS) technique was used for the thermal deposition of a multicomponent mixture made up of an Y-TZP/Al2O3 matrix with SiC particles. Two suspensions of Y-TZP and Al2O3 with different SiC particles content (6?wt% and 12?wt%) were tested as feedstocks in the SPS process. Three stand-off distances were varied in order to assess coating microstructure and evaluate the presence of SiC in the final coatings. Coatings were characterised in terms of porosity, microstructure and phase distribution. The estimate of the amount of SiC in the coating was carried out by XRD technique.Findings showed typical cauliflower-like SPS microstructure which intensifies with stand-off distance. Coatings porosity varied significantly between 8% and 25% whereas minimum porosity was found for the intermedium stand-off distance of 40?mm.Microstructure analysis also revealed the presence of SiC particles in the coatings which was confirmed by EDX analysis, overall XRD tests as well as TG analysis. Finally, evaluation of SiC content in the final coatings by means of XRD analysis showed that most of SiC particles (c.a 80%) of the feedstocks were preserved in the final coatings. 相似文献
4.
Lan Wang Xiaoyan Shu Facheng Yi Dadong Shao Kuibao Zhang Haibin Zhang Xirui Lu 《Journal of the European Ceramic Society》2018,38(7):2863-2870
A series of Nd and Ce co-doped Gd2-xNdxZr2-yCeyO7 (0.0 ≤ x, y ≤ 2.0) ceramics were rapidly fabricated through spark plasma sintering (SPS) within 3?min. The effects of Nd and Ce contents on the phase composition, lattice parameter, active modes, microtopography and microstructure have been investigated in detail. XRD studies reveal that the compositions corresponding to 0.0 ≤ y ≤ 1.0 show a single phase and beyond 1.0 exhibit multiphase. The lattice parameters increase with elevated Nd and Ce content. The grains are densely packed on each other with cube-like shape, and the elements are almost homogeneously distributed in the compound. This synthetic method provides a simple pathway for the preparation of highly densified single phase ceramic at 1600–1700 ℃ for 3?min under pressure of 80?MPa. 相似文献
5.
《Journal of the European Ceramic Society》2020,40(13):4623-4634
In this work, HA/bioactive glass Functionally Graded Materials (FGMs) are obtained for the first time by means of Spark Plasma Sintering (SPS). Two series of highly dense 5 layered products, namely FGMS1 and FGMS2, are prepared under optimized SPS conditions, i.e. 1000 °C/2 min/16 MPa and 800 °C/2 min/50 MPa, respectively, using a die with varying cross section.Results arising from XRD, SEM, mechanical and biological characterization in SBF, evidence that lower temperature and higher-pressure levels used for FGMS2 samples provide better materials in terms of microstructure, compactness, hardness, elastic modulus and in vitro bioactivity. Indeed, a fully sintered and crack-free microstructure with no crystallisation at the top layer (100% bioactive glass) is correspondingly produced.The obtainment of such FGMs is quite promising, since it permits to vary the relative volume fractions of the two constituents and, consequently, tailor the biological response for specific clinical applications. 相似文献
6.
《Journal of the European Ceramic Society》2020,40(2):417-426
Nacre-like alumina manufactured using spark plasma sintering shows a strikingly different mechanical behaviour compared to conventional alumina. A range of sintering conditions were applied to micron-sized alumina platelet powders to form alumina with different nacre-like microstructures, density, grain size and flexural strength. We show that a microstructure of aligned sintered platelets not only mitigates the typical issue of brittleness, but also has extraordinary energy absorption capabilities. It can withstand an impact with up to three times the kinetic energy required to break monolithic alumina while maintaining structural integrity. The high-rate compressive strength is shown to be more than 50% higher than that of monolithic alumina and we show energy absorption mechanisms such as crack deflection and branching to be present. Our approach provides a fast and effective way of manufacturing aligned nacre-like ceramic microstructures that maintain structural integrity through energy dissipation and interlocking mechanisms. 相似文献
7.
《Ceramics International》2020,46(10):15786-15792
A glycine–nitrate self-propagating high temperature synthesis (SHS) was developed to produce composite Y2O3–MgO nanopowders. Based on the thermodynamic calculations a 0.25YMg2(NO3)7-0.75NH2CH2COOH precursor composition was selected to prepare low agglomerated uniform composite yttria-magnesia powder. Near full dense composite ceramics were fabricated based on the prepared powders by the spark plasma sintering method. IR-transmittance and hardness of the Y2O3–MgO ceramics were studied in correlation with sintering conditions. The best transmittance of 80.9%@5 μm and Hv = 10.2 GPa were measured for the sample obtained at 1150 °C. 相似文献
8.
In this study, the effect of sintering parameters on densification and fracture toughness of spark plasma sintering ZrB2-SiC nanocomposites was evaluated. For this purpose, ZrB2-??30?vol% SiC nanocomposites in the conditions of ?1600?°C-4?min, 1700?°C-4?min, 1800?°C-4?min, 1800?°C-8?min, 1800?°C-12?min? were sintered.? Scanning Electron Microscopy (SEM) was used in order to investigate the ?microstructural variations. The bulk density was measured accoring to ASTM C 373–88. Single edge notch beam (SENB) method was used to ?determine the fracture toughness of samples. Microstructural observations showed that ?an increase in sintering temperature led to slight ?increase in SiC grains size but no sensitive variation in ZrB2. However, increasing the sintering time resulted to increase both ZrB2 and SiC grain size. Also, it was found, temperature and time ascent always increases the relative density. In addition, it was concluded that optimal temperature and time to reach the highest fracture toughness are 1800?°C and 8?min, respectively. Investigation of SEM images of the Vickers indent and their path propagation showed that the deviation and branching of crack are the most important toughening ?mechanisms in ZrB2-SiC nanocomposites.? 相似文献
9.
Fen Luo Hexi Tang Xiaoyan Shu Zhi Chen Chen Xu Guilin Wei Dong Wu Shunzhang Chen Haibin Zhang Yi Xie Wenxiao Huang Lan Wang Xirui Lu 《Ceramics International》2021,47(5):6329-6335
To simplify the immobilized process of nuclear waste, synthetic Gd2Zr2O7 ceramic was employed to immobilize simulated An3+ (Nd3+) by spark plasma sintering (SPS) without any ion occupation or valence design. Sintering and characterization of immobilized simulated An3+ with various doping amounts were carried out. The effects of Nd2O3 content on the phase composition, active modes, micro-graph and density of the sintered ceramics were investigated. When the Nd2O3 doped amount reached up to 50 mol%, the raw peak of Nd2O3 existed. The sintered ceramics kept a single fluorite phase when Nd2O3 solubility achieved to 40 mol%. The sintered ceramics presented a well crystalline phase and the elements distributed evenly. In addition, as the Nd2O3 doped amount increase, the density and Vickers hardness values of Nd2O3 doped sample decrease. 相似文献
10.
《Ceramics International》2022,48(16):23151-23158
SiC composite ceramics have good mechanical properties. In this study, the effect of temperature on the microstructure and mechanical properties of SiC–TiB2 composite ceramics by solid-phase spark plasma sintering (SPS) was investigated. SiC–TiB2 composite ceramics were prepared by SPS method with graphite powder as sintering additive and kept at 1700 °C, 1750 °C, 1800 °C and 50 MPa for 10min.The experimental results show that the proper TiB2 addition can obviously increase the mechanical properties of SiC–TiB2 composite ceramics. Higher sintering temperature results in the aggregation and growth of second-phase TiB2 grains, which decreases the mechanical properties of SiC–TiB2 composite ceramics. Good mechanical properties were obtained at 1750 °C, with a density of 97.3%, Vickers hardness of 26.68 GPa, bending strength of 380 MPa and fracture toughness of 5.16 MPa m1/2. 相似文献