Al2O3-3YTZP-Graphene multilayers produced by tape casting and spark plasma sintering

This work aims to establish a colloidal route to obtain laminates of alumina zirconia combining layers with and without graphene. Green tapes of alumina, alumina with 5 vol.% of 3Y-TZP and alumina with 5 vol.% of 3Y-TZP and graphene-oxide (2 vol.%) were obtained by aqueous tape casting. It is possible to design materials for different structural applications with a controlled microstructure with a high number of different layers. The tapes were punched into 20-mm discs, joined to form laminates alternating up to 18-layers, and sintered in one-step by spark plasma sintering (SPS) at 1400 degrees C. It has demonstrated that there is a significant graphite diffusion provoked by the required graphite holders into the SPS-furnace. Dense laminates with layer thicknesses similar to 100 mu m and good cohesion between layers were obtained. Nanoindentation results showed that hardness and elastic modulus values were higher than 27 GPa and 300 GPa, respectively, and similar for all layers. Crown Copyright (C) 2014 Published by Elsevier Ltd. All rights reserved.This work has been supported by Spanish Ministry of Economy and Competitiviness (MAT2012-31090). A. S. A. Chinelatto thanks to CAPES - Programa Ciencias sem Fronteiras (Brazil) for the concession of a fellowship for post-doctoral sabbatical grant in ICV-CSIC, Spain. A. Borrell, acknowledges the Spanish Ministry of Science and Innovation for her Juan de la Cierva contract (JCI-2011-10498) and the Generalitat Valenciana by the financial support for the BEST/2012/302 grant. Authors thank to Nanoinnova Technologies (Spain) for supplying the graphene oxide and helpful discussions.Rincón, A.; Moreno, R.; Chinelatto, ASA.; Gutierrez-Gonzalez, CF.; Rayón Encinas, E.; Salvador Moya, MD.; Borrell Tomás, MA. (2014). Al2O3-3YTZP-Graphene multilayers produced by tape casting and spark plasma sintering. Journal of the European Ceramic Society. 34(10):2427-2434. https://doi.org/10.1016/j.jeurceramsoc.2014.02.011S24272434341

Characterization of high-energy milled alumina powders Caracterização de pós de alumina submetidos a moagem de alta energia

The utilization of reactive high-energy milling has been reported for the synthesis of ceramic powders namely, metal oxides, carbides, borides, nitrides or mixtures of ceramics or ceramic and metal compounds. In this work, high-energy milling was used for reduction of alumina powders to nanometric particle size. The ceramic characteristics of the powders were analyzed in terms of the behavior during deagglomeration, compaction curves, sintering and microstructure characterization. It was observed that the high energy milling has strong effect in producing agglomeration of the nanosized powders. This effect is explained by the high-energy impact of the balls, which may fracture particles or just cause the particles compacting. In this case, strong agglomerates are produced. As the powder surface area increases, stronger agglomerates are produced.<br>Tem sido amplamente divulgada a utilização da moagem reativa de alta energia para a síntese de pós cerâmicos de óxidos de metais, carbetos, boretos, nitretos ou misturas de compostos cerâmicos ou compostos cerâmicos e metálicos. Neste trabalho, a moagem de alta energia (não reativa) foi utilizada para a redução de pós de alumina para partículas de dimensões nanométricas. As características cerâmicas dos pós obtidos foram analisadas a partir de resultados de comportamento durante a desaglomeração, curvas de densificação, sinterização e caracterização de microestrutura. Observou-se que a moagem de alta energia tem forte efeito de aglomeração dos pós com partículas em dimensões nanométricas. Esse efeito é explicado pelo impacto de alta energia das bolas, os quais podem fraturar as partículas ou apenas causar a compactação das mesmas. Nesse último caso, que sempre ocorre, são formados aglomerados de alta resistência. O aumento da área superficial do pó produz aglomerados mais resistentes

Al2O3 // 3Y-TZP // Graphene multilayers produced by tape casting and spark plasma sintering. A rheological, sintering and characterization study

Trabajo presentado al 13th International Ceramics Congress celebrado en Montecatini Terme (Italia) del 9 al 17 de junio de 2014.The aim of this work is to propose a procedure to obtain dense and free defects multilayered alumina-zirconia coatings with graphene. Green tapes of alumina alumina+5vol.%3Y-TZP and alumina+5vol.%3Y-TZP mixed with graphene-oxide (2 vol.%) were obtained by aqueous tape casting. of the three compositions. The rheological behaviour of concentrated suspensions was optimized considering the sonication mode and time and the content of deflocculant. Green tapes were punched and laminated in order to form ceramic laminates alternating up to 18 layers The obtained multilayer discs with 20 mm in diameter were sintered by spark plasma sintering (SPS) technique at 1400 ºC under vacuum and with pressure. By means of optical and electronic microscope images of the ceramic cross-sections, it was revealed that the sintered laminates had a high green density and layer thicknesses of 100 µm without any apparent defect showing a good cohesion between them. Raman spectroscopy analysis confirmed the presence of tetragonal zirconia in alumina coatings and revealed carbon content inside all the samples. Nanoindentation results revealed that hardness and elastic modulus values were similar for all coatings, being higher than 27 GPa and 300 GPa, respectively.Peer Reviewe

Al2O3-3YTZP-graphene multilayers produced by tape casting and spark plasma sintering

This work aims to establish a colloidal route to obtain laminates of alumina-zirconia combining layers with and without graphene. Green tapes of alumina, alumina with 5. vol.% of 3Y-TZP and alumina with 5. vol.% of 3Y-TZP and graphene-oxide (2 vol.%) were obtained by aqueous tape casting. It is possible to design materials for different structural applications with a controlled microstructure with a high number of different layers. The tapes were punched into 20-mm discs, joined to form laminates alternating up to 18-layers, and sintered in one-step by spark plasma sintering (SPS) at 1400 °C. It has demonstrated that there is a significant graphite diffusion provoked by the required graphite holders into the SPS-furnace. Dense laminates with layer thicknesses ~100 μm and good cohesion between layers were obtained. Nanoindentation results showed that hardness and elastic modulus values were higher than 27. GPa and 300. GPa, respectively, and similar for all layers. © 2014.This work has been supported by Spanish Ministry of Economy and Competitiviness (MAT2012-31090). A. S. A. Chinelatto thanks to CAPES – Programa Ciências sem Fronteiras (Brazil) for the concession of a fellowship for post-doctoral sabbatical grant in ICV-CSIC, Spain. A. Borrell, acknowledges the Spanish Ministry of Science and Innovation for her Juan de la Cierva contract (JCI-2011-10498) and the Generalitat Valenciana by the financial support for the BEST/2012/302 grant.Peer Reviewe