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Refractories are complex materials used at high temperature, in severely corrosive atmospheres and in contact with aggressive liquids. The high temperatures imply that such systems tend to equilibrium and this is frequently attained during service; at least local equilibrium is achieved. This allows the basic principles of phase diagrams to be used in this technology. Traditionally, refractories have been designed to be close to equilibrium so that in-service changes were restricted. Currently, additions of raw materials are often made that will react in use, in a controlled manner, to give favorable effects under the service conditions. Equilibrium diagrams are valid not only for determining the thermodynamic tendency but also for predicting the final equilibrium state and to know the way through which the material moves into the final state. In this context equilibrium diagrams become a powerful tool for a better understanding of the behavior of refractrories during service. After a general consideration on the importance of phase equilibrium diagrams in this field, criteria for using equilibrium diagrams, as a tool for improving traditional refractories and/or designing advanced or new refractories, will be given. Pertinent examples in different systems will be discussed.
This paper compiles and reviews the last plenary lecture given by Professor Salvador De Aza on the subject.

In this paper we set out, discuss and evaluate the work on Mullite-zirconia composites obtained by reaction  sintering led and inspired by Salvador de Aza on the basis of  ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2) multicomponent phase equilibrium diagrams. We analyze their impact on different areas of ceramic science and technology such as refractory grogs, aluminum industry, etc. The possible fields of future applications such as dental prosthesis replacing partially stabilized zirconia materials with rare earths are also reported.

A full compilation of Salvador De Aza works on biomedical materials is a huge task beyond the aim of this paper; instead it is intended to stand out De Aza’s thoughts and leadership in the field of Bioceramics and to pay tribute to his memory. The most outstanding works of Professor Salvador De Aza related to Bioceramics, from the point of view of the authors, are commented and discussed.
Topics the authors chose among many other De Aza’s works on biomedical materials are: The prediction and demonstration of bioactivity in pseudo-wollastonite ceramics; the use of phase diagrams to design bulk-bioactive ceramics with eutectic microstructures; the relationship between bioactivity and microstructure in ceramic biomaterials; and the studies on the polymorphic phase transitions in tricalcium phosphate.

This work deals with an original class of porcelain produced under the direction of Bartolomé Sureda in the last years (1803-1808) of the Royal Porcelain Factory of Buen Retiro. The results of the chemical and mineralogical analysis of a selection of tableware, tiles and sculpture shards, found in the archaeological excavation (1996) of the site where the factory was built, confirm the production of a new hard-paste porcelain where the kaolin was substituted by a magnesium clay, the sepiolite. The characteristics of pastes and glazes and the investigation of the historic and scientific contexts of porcelain and white earthenware in Europe have allowed establishing the reasons and the technical parameters of this production. Replicas of the paste were done in the laboratory to assert the raw materials and the firing conditions of this porcelain.