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21.
Ke Gan Yanjiao Gai Yali Wang Jie Cui Yuju Lu Xiaoyan Zhang Jingjing Liu Jie Xu Jinlong Yang 《International Journal of Applied Ceramic Technology》2020,17(1):274-284
A direct coagulation casting method for silicon carbide ceramic suspension using dispersant crosslink reaction is reported. Polymer electrolyte (polyethyleneimine, PEI) was used as dispersant to prepare silicon carbide suspension. Common food additives (carboxymethyl cellulose, CMC) were used to coagulate the electrosteric stabilized silicon carbide suspension. There was a well disperse silicon carbide suspension with 0.2 wt% PEI at pH = 5-6. Influence of coagulant on viscosity and zeta potential of the silicon carbide suspension was investigated. It indicates that the high solid loading silicon carbide suspension can be destabilized and coagulated at elevated temperature. It can be attribute to the gradual decrease of electrosteric force due to the crosslink reaction between PEI and CMC. Silicon carbide wet green body with compressive strength of 1.99 MPa could be demolded at 70°C which is higher than that prepared by traditional DCC and dispersant reaction method for nonoxide ceramics. Dense silicon carbide ceramics with relative density above 98.8% and 99.3% had been prepared by liquid phase pressureless and hot pressed sintering, respectively. 相似文献
22.
Franc ZUPANIČ Carlos A. NUNES Gilberto C. COELHO Paula L. CURY Gorazd LOJEN Tonica BONČINA 《中国有色金属学会会刊》2018,28(11):2226-2235
A novel, Nb- and Si-rich and Be-free Ni-based alloy was cast by two methods of investment casting and continuous casting to study the microstructure evolution during solidification and its mechanical properties. The solidification of the alloy started with the primary crystallization of FCC-γ, followed by a binary eutectic reaction, with the formation of a heterogeneous constituent: FCC-γ+G-phase, which replaced the low-melting eutectic (FCC-γ+NiBe) in the Be-bearing alloys. AlNi6Si3 and γ′ formed during the terminal stages of solidification by investment casting, while the formation of AlNi6Si3 was suppressed by continuous casting. The Scheil solidification model agreed very well with the experimental results. 相似文献
23.
《Ceramics International》2020,46(3):2640-2647
B2O3 and Li2O (B/L)-added Ba0.6Sr0.4TiO3 (BST) ceramics sintered at 940 °C exhibited a dense microstructure with large grains. The amount of B/L additive was 4.5 wt% with a B/L ratio of 1.5:1. The B/L-related liquid phase assisted the densification of the BST ceramics. This BST ceramic displayed a large dielectric constant (εr) of 2834 with a low dielectric loss (tan δ) of 0.21% at 1.0 MHz. It also displayed a large tunability (28.2% at 10 kV/cm) and a high figure of merit (FOM) of 134. BST thick-films were synthesized using the tape casting method. The thick-film densified at 940 °C exhibited a large tunability of 18.7% at 10.0 kV/cm and an FOM of 208; these are higher than the values reported in the literature. Multilayer ceramics (MLCs) consisting of five layers of 40-μm-thick BST thick-films and Ag electrodes were also fabricated at 940 °C. No diffusion occurred between the Ag electrode and BST thick-film. A large tunability of 67.6% at 52 kV/cm with a high FOM of 294 was obtained from this MLC. This verified that the B/L-added BST ceramic is effective for application in tunable multilayer devices. 相似文献
24.
Chia En Liu Wen Chieh Lan Hao Ting Yu Han Lin Yang I. Tseng Liu Hsiao Ping Hsu Chung Wen Lan 《International Journal of Applied Ceramic Technology》2020,17(1):146-152
Silicon kerf loss during wafer slicing and the broken quartz crucibles after silicon casting are two major solid wastes from photovoltaic (PV) industry. Especially, the recycle of kerf-loss silicon has become an urgent issue because near 100 000 t of solid wastes are generated every year. One of the most meaningful recycle routes of the kerf-loss silicon is to make silicon nitride crucibles to replace the quartz crucibles. In this study, we demonstrated how this is feasible through acid leaching refining, slip casting, and nitridation. The reaction-bonded silicon nitride (RBSN) crucibles after oxidation were found pure enough for silicon ingot growth. More importantly, they could be reused after ingot growth. With the present examples, the potential of using the kerf-loss silicon for fine ceramics is prominent. 相似文献
25.
采用热喷涂工艺在压铸态AZ91D合金表面制备了Al涂层,研究了热处理温度和保温时间对AZ91/Al涂层界面组织形貌的影响,并对比分析了扩散层的耐腐蚀性能和耐磨性能。结果表明,热处理前Al涂层与基材为机械结合,热处理后Al涂层与AZ91合金基材的界面处可形成冶金结合扩散层,且随着保温时间延长,扩散层厚度不断增加;热处理温度在375 ℃以下时扩散层主要由β-Mg17Al12相构成,375 ℃×8 h热处理后为α-Mg+β-Mg17Al12相,425 ℃×1 h热处理后为γ-Mg2Al3和β-Mg17Al12相。AZ91合金基材和扩散层腐蚀电位从高至低顺序为γ>β>α+β>AZ91合金基材,扩散层的腐蚀电流密度均低于AZ91合金基材,阻抗谱图中容抗弧半径从大至小顺序为γ>β>α+β>AZ91合金基材,扩散层的耐腐蚀性能均优于AZ91合金基材;γ、β和α+β扩散层的摩擦稳定性系数都高于AZ91合金基材,而磨损速率和磨痕宽度都要小于AZ91合金基材,其中β扩散层的磨损速率和磨痕宽度最小,具有最佳的抵抗磨损的能力。 相似文献
26.
An-guo Wang Zhou-hua Jiang Yan-chun Lou Ji Tang Yun-long Xiong Yan-wu Dong Yan-wu Dong Fu-bin Liu Jing-chang Cheng Rui Chen 《中国铸造》2020,(1):48-55
Electroslag casting(ESC)is an important method to produce high quality castings.In this study,the ESC up-pulling inner mold method(EUPIM)was used to produce hollow cylindrical castings with the multiple consumable electrodes.The radial deformation,the axial and radial internal stress of the inner mold,and the axial internal stress of the slag shell were analyzed using the finite element method(FEM)with the aid of ANSYS software.The ProCAST software was used to calculate the specific heat,heat conductivity and density curve of Cu.Simulation results show that the radial deformation,the axial and radial internal stress of the inner mold,and the axial internal stress of the slag shell near the slag-metal interface of hollow cylndrical casting gradually increase from 0 s to 360 s after the ESC starting(slagging)process but before applying the up-pulling force.The suitable initial up-pulling moment of the inner mold is at around 180-198 s after the starting process. 相似文献
27.
28.
分析意大利corefon涂料的特性,研究在不同铸件应用中的典型案例。结果表明,corefon涂料可以提升汽车发动机缸体缸盖内腔清洁度、解决工程液压阀体内腔油道粘砂烧结问题、提高增压器零部件涡轮涡壳气道光洁度。铁型覆膜砂外型喷涂corefon涂料后,浇铸的铸件表面光滑,无粘砂、无烧结,不需要人工打磨和特别抛丸处理。充分体现了corefon涂料在性能上的优越性,可以解决铸造厂铸件内腔粘砂、烧结、表面粗糙的问题。 相似文献
29.
福建罗源闽光根据三钢(集团)发展规划需要,在2号连铸机150 mm×150 mm断面的基础之上,增加160 mm×230 mm矩形坯断面。通过设备改造和工艺参数优化,在满足铸坯质量的前提下,达到炉机匹配与快速切换断面的双目标,满足了生产要求。 相似文献
30.
《Journal of the European Ceramic Society》2020,40(5):1975-1982
Free-standing Li1.5Al0.5Ti1.5P3O12 electrolyte sheets with a thickness of 50–150 μm were prepared by tape casting followed by sintering at 850–1000 °C in air. While a sintering temperature of 850 °C was too low to achieve appreciable densification and grain growth, a peak relative density of 95% was obtained at 920 °C. At higher sintering temperatures, the microstructure changed from a bimodal grain size distribution towards exclusively large grains (> 10 μm), accompanied by a decrease in relative density (down to 86% at 1000 °C). In contrast, ionic conductivity increased with increasing sintering temperature, from 0.1 mS/cm at 920 °C to 0.3 mS/cm at 1000 °C. Sintering behavior was improved by adding 1.5% of amorphous silica to the slurry. In this way, almost full densification (99.8%) and an ionic conductivity of 0.2 mS/cm was achieved at 920 °C.Mechanical characterization was carried out on the almost fully densified material, yielding elastic modulus and hardness values of 109 and 8.7 GPa, respectively. The fracture strength and Weibull modulus were also characterized. The results confirm that densification and reduction of grain size improve the mechanical properties. 相似文献