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It is attempt to enhance the thermal conductivity of Al 2 O 3 /glass by introducing one-dimensional materials into the Al 2 O 3 /glass composite which are fired at 850 °C. The influences of AlN whiskers, carbon fibers and copper fibers on the thermal conductivity of Al 2 O 3 /30 vol% glass composites were studied by the laser thermal conductance instrument, XRD and SEM. The results show that the adding of one-dimensional materials with excellent thermal conductivity remarkably enhances the thermal property of the composites. The oxidation of AlN or copper was not detected when the composites were sintered at 850 °C with 25 MPa for 45 min in a nitrogen atmosphere. Fibers are more effective to enhance the densification of the composites than the whiskers. The highest value of the thermal conductivity of Al 2 O 3 /glass/copper fiber achieves 38.9 W (mK) −1 , an increase of about 500%. The clear enhancement of the thermal conductivity is due to the bridging network formed by the one-dimensional materials. [ABSTRACT FROM AUTHOR]

Ceramic-Al substrates with co-continuous ceramic and metal phases, which exhibit high thermal conductivity and compatible coefficient of thermal expansion (CTE), have been widely investigated through the process of die-casting. In this research, a kind of powder sintering process was proposed for fabricating ceramic-Cu composite substrates with co-continuous phases. Copper fiber (Cuf) has excellent thermal conductivity and large aspect ratio, making it an ideal material to form bridging network structures in the ceramic-Cu composite. To maintain the large aspect ratio of Cuf, and densify the composite substrate, ZnO-SiO2-CaO glass was introduced as a sintering additive. Both Al2O3/glass/Cuf and Al2O3/30glass/Cup composite substrates were hot-pressed at 850 °C under 25 MPa. Experimental results showed that the thermal conductivity of Al2O3/30glass/30Cuf composite substrate was as high as 38.9 W/mK, which was about 6 times that of Al2O3/30glass; in contrast, the thermal conductivity of Al2O3/30glass/30Cup composite substrate was only 25.9 W/mK. Microstructure observation showed that, influenced by hot press and corrosion of molten ZnO-SiO2-CaO glass, the copper fibers were deformed under hot-pressing, and some local melting-like phenomena occurred on the surface of copper fiber at 850 °C under 25 MPa. The molten phase originating from surface of Cuf welded the overlapping node of copper fibers during cooling process. Finally, the interconnecting metal bridging in ceramic matrix was formed and behaved as a rapid heat-dissipating channel, which is similar to substrates prepared through die-casting process by porous ceramic and melted Al. [ABSTRACT FROM AUTHOR]

[Display omitted] • Best modification effect is achieved by titanate coupling agent M3. • Activation index and oil absorption value of modified nanoparticles are improved. • FT-IR analysis showed that the coupling agent was attached to the nanoparticles. • Modification of nanoparticles improved the quality of the micro-nano green tape. Nanoparticles are widely used for the fabrication of advanced ceramics. Unfortunately, nanoparticles tend to agglomerate when added to ceramic slurries for tape casting. In this study, the surface modification process of alumina nanoparticles was studied. Coupling agents were introduced to modify the surface of alumina nanoparticles to prevent their agglomeration in ceramic slurry during tape casting. The effects of variation in the modifier dosage, modification temperature, and modification time on the activation index and oil absorption value of modified alumina nanoparticles were investigated. The influence of the modification process on microstructure and properties of the micro-nano green tapes was also investigated. Experimental results showed that the best modification effect was achieved via modification of the alumina nanoparticles with 2.5 wt% of titanate coupling agent at 60 °C for 20 min. The activation index increased from 2% for the raw alumina nanoparticles to 94.9% for the modified alumina nanoparticles, while the oil absorption value decreased from 75.2 mL/100 g to 55.8 mL/100 g. The sedimentation rate of the slurry decreased from 26% to 4% after modification of the nanoparticles, and the volume of nanoparticles increased appreciably from 35 vol% to 45 vol%. The surfaces of the green tapes prepared using slurries with modified alumina nanoparticles were smooth without visible defects. [ABSTRACT FROM AUTHOR]