Amparo Borrell Tomás

By Amparo Borrell and Maria Dolores Salvador

Processing of ceramic materials has also a strong impact in the quality of the consolidated body, as it plays a key role in the resulting microstructure and, as a consequence, in its final properties. Advanced ceramic materials are commonly processed as powders and densified via a high-temperature process. Traditional processing techniques include hot isostatic pressing, mold casting, and sintering in conventional ovens. As ceramics require very high processing temperatures compared to metals and polymers, these processes tend to be very energy intensive and result in higher production costs to the manufacturers. Therefore, new technologies known as nonconventional sintering techniques, such as microwave technology, are being developed in order to reduce energy consumption, while maintaining or even improving the characteristics of the resulting ceramic material. This novel and innovative technology aims at helping industrial sectors lower their production costs and, at the same time, lessen their environmental impact. On the other hand, it is interesting and necessary to know and explore the basic principles of microwaves to advance in the development of materials that demand, every day more, the different industrial sectors. This chapter presents the most recent advances of two materials with a great industrial future: zirconia and lithium aluminosilicate.

Part of the book: Sintering Technology

By Rut Benavente, Maria Dolores Salvador and Amparo Borrell

Ceramics are increasingly used as structural materials with biomedical applications due to their mechanical properties, biocompatibility, esthetic characteristics and durability. Specifically, zirconia-based compounds are commonly used to develop metal-free restorations and dental implants. The consolidation of ceramics is usually carried out through powders by means of processes that require a lot of energy, as long as processing times and high temperatures (over 1400°C) are required. In the recent years, new research is being developed in this field to reduce both energy consumption and processing time of ceramic powders. One of the most promising techniques for sintering ceramics is microwave heating technology. The main objective of this chapter is to obtain highly densified zirconia-alumina compounds by microwave technology. After sintering, the materials are characterized to determine whether the final properties meet the mechanical requirements for their final applications as dental material. Finally, the characterization of specimens treated by low-temperature degradation (LTD) is carried out after each 20 h of LTD exposure up to 200 h. In addition, the quantification of monoclinic phase by micro-Raman spectroscopy, analysis by AFM and Nomarski optical microscopy and assessment of the roughness and mechanical properties (hardness and Young’s modulus) by nanoindentation technique have been studied.

Part of the book: Smart and Advanced Ceramic Materials and Applications

By Eugeni Cañas, Rut Benavente, Amparo Borrell and Ma Dolores Salvador

Advanced ceramic coatings have been largely used in several industrial fields such as aerospace, automotive, power generation, medical or petrochemical, in order to protect or functionalise the surface of different materials. In modern industries, thermal spray processes are the most used ones to manufacture advanced ceramic coatings due to their cost advantages, flexibility and efficiency in processing ceramic materials, especially those with high melting temperature. This chapter provides a brief overview of the progress and current state of different thermal sprayed ceramics and summarises the future trend in this field. Therefore, various advanced ceramics, such as yttria-stabilised zirconia, alumina, hydroxyapatite and bioactive glasses, have been selected for analysis and discussion.

Part of the book: Ceramic Materials

By Amparo Borrell, Rut Benavente, René M. Guillén, María D. Salvador, Vaclav Pouchly, Martina Ilcikova, Richard Krumpolec and Rodrigo Moreno

Throughout the ceramic processing cycle, it is well known that a small change in the surface energy of as-received powders can have a considerable effect on the final properties of consolidated materials. The main objective of this chapter is to describe the design and manufacture of new ceramic materials based on strontium-doped lanthanum manganites, LSM (La_0.8Sr_0.2MnO₃) and LSM-8YTZP composites, for cathode in solid oxide fuel cells (SOFC) applications due to their excellent properties, by modifying the surface energy of the starting powder using techniques, such as Diffuse Coplanar Surface Barrier Discharge (DCSBD) and atomic layer deposition (ALD). Subsequently, in order to evaluate the activation energy and optimise the sintering behaviour of these powders, the Spark Plasma Sintering (SPS) technique will be used. SPS allows the complete densification of pieces by fast and low-energy consumption processing.

Part of the book: Ceramic Materials

By Alina Pruna, Ashley Bonilla, Rut Benavente, Maria D. Salvador-Moya, David Busquets-Mataix and Amparo Borrell

The synthesis of lead-free (Na_0.5K_0.5)NbO₃ (KNN) ceramics for potential piezoelectric applications is reported by conventional solid-state reaction between alkaline carbonates and Nb₂O₅. Prior to the synthesis, the reactant powders and their corresponding stoichiometric mixture are alumina ball-milled to homogenize the particle size and as pre-activation treatment, respectively. The synthesis of the KNN-based ceramics was investigated systematically with the duration of the ball milling and calcination conditions in terms of mass change evolution at involved temperature steps. The properties of the obtained ceramics including phase structure, morphology, composition, relative density and microhardness were assessed by Field Emission Scanning Electron microscopy, Energy Dispersive Spectroscopy and X-ray diffraction. The obtained results indicate that longer ball milling duration is detrimental to the synthesis of KNN ceramics while tailoring of the KNN properties can be achieved by adjustment of calcination conditions including calcination rate, calcination temperature stage and calcination dwell duration.

Part of the book: Advanced Ceramic Materials

By Fabiola Colmenero Fonseca, Amparo Borrell, María Dolores Salvador Moya, Rut Benavente and Juan Francisco Palomino Bernal

A study on the technological innovations in the development of ceramic membranes for water treatment is provided. These membranes have proven to be effective in removing contaminants in the water, such as heavy metals and pathogens. It discusses the different materials based on oxides such as Al₂O₃, TiO₂, SiO₂, and ZrO₂, used in manufacturing, as well as fabrication techniques and surface modifications that have improved their properties. In addition, the environmental and economic impact on water treatment plants is addressed. From a financial point of view, implementing membranes can be an investment, both in acquiring the membranes and in the infrastructure. Membrane maintenance and operating costs are often high, which can affect the economic viability of the treatment plant. The results suggest ceramic membranes are a viable and efficient option for treating polluted water.

Part of the book: Advanced Ceramic Materials