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Novel 1:1 Yttria partially stabilized zirconia (PSZ) - aluminum borate (AB: Al11B4O33) ceramic composites were prepared and characterized by a simple direct sintering process of PSZ-mixtures. Sintering was performed below 1300?C to minimize the decomposition of borate. Phases were corroborated by XRD. SEM permitted to characterize the microstructure as interlocking needles of - rounded by PSZ grains. Porous microstructure configuration was achieved by the proposed processing route. Porosity was within 30% for samples thermally treated at 1200 and 1300?C. Mechanical behavior was evaluated by diametral compression. A fragile behavior was observed. Both strength and apparent Young modulus were evaluated being ?30 MPa and ?3 GPa respectively; values four times higher than the corresponding alumina-AB composite. This is more important when firing at higher temperature. The density of the obtained composites coupled with the mechanical behavior are the main characteristics of this novel composite with potential structural, insulating and filtering applications.

A Zr-modified bentonite (B-OHZr) obtained by intercalation of OH-Zr species was obtained, and its thermal transformations at > 800 °C were studied. Raw clay and B-OHZr were characterized by X-ray diffraction, thermogravimetric and differential thermal analysis, and its sintering behavior was studied by hot-stage microscopy. Two Zr-based phases—tetragonal zirconia and zircon—were observed in thermally treated B-OHZr with a sharp decrease in amorphous glassy phase in comparison with the parental clay. An increase in refractoriness was observed in B-OHZr, enabling the sintering of samples up to 1300 °C, while the parental clay bloated and deformed with thermal treatment. The Zr interlayering enhanced the refractoriness at high temperatures of the parental clay, eliminating thermal expansion (bloating) and enabling sintering at T > 1000 °C. The observed features and thermochemical processes enlighten the temperature usage range of these kinds of materials. Finally these results yield promising features for potential use of these clays for the preparation of ceramic materials with zircon content., Centro de Tecnología de Recursos Minerales y Cerámica

An attractive way to obtain low cost calcium zirconate (CaZrO3) composites is mixing natural limestone or dolomite with zirconia. These CaZrO3 based ceramic composites were often investigated as a promising high refractory for casting metal alloys, cements, thermal and environmental barrier coating. In this study the sliding wear, fracture mechanism and friction properties of a CaZrO3-MgO-ZrO2 ceramic against ZrO2 and steel counter bodies was carried out. Wear and fracture surface mechanisms, influence of its impurities and individual phases are discussed. The composite presents a coefficient of friction higher in ceramic/metal than in ceramic/ceramic pair, but the specific wear it is significantly higher when tested with the ZrO2 ball. The fracture surfaces presenta dominant transgranular fracture when tested with steel and intergranular fracture against ZrO2. Fil: Silva, Abílio. Instituto de Cerámica y Vidrio de Madrid; España. Consejo Superior de Investigaciones Científicas; España Fil: Booth, Raul Fernando Nicolas. Instituto de Cerámica y Vidrio de Madrid; España. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Garrido, Liliana Beatriz. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Aglietti, Esteban Fausto. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Pena, Pilar. Consejo Superior de Investigaciones Científicas; España. Instituto de Cerámica y Vidrio de Madrid; España Fil: Baudín, Carmen. Consejo Superior de Investigaciones Científicas; España. Instituto de Cerámica y Vidrio de Madrid; España

Composites of the ZrO2-CaO-Al2O3 system exhibit high corrosion resistance and high chemical stability, these being suitable properties for enhanced performance as refractories. In this work composites based on ZrO2-CaAl4O7 (CA2) were developed by reaction sintering of two pure ZrO2 powders with different particle size (d50 = 0.44 μm and d50 = 8 μm) mixed with high-alumina cement. The effects of CaO to ZrO2 molar ratio, particle size of ZrO2 and sintering temperature on densification, c-ZrO2 formation, microstructure and mechanical properties (Vickers hardness, dynamic Young's modulus and compressive strength) were determined. Porosity and mean pore size of composites reduced with decreasing both particle size of ZrO2 and CaO content. The highest compression strength of ∼350 MPa and hardness of 6 GPa corresponded to dense ZrO2-based composite with 15 vol.% CA2 sintered at 1 400°C. Fil: Bruni, Yesica Lorena. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina Fil: Booth, Raul Fernando Nicolas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Garrido, Liliana Beatriz. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Aglietti, Esteban Fausto. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina

The aim of this work is to determine the values of the hardness and elastic modulus of the phases present in CaZrO3-MgO-ZrO2 composites and to analyse their contribution to the composite properties. Two materials previously developed with the same major phases (CaZrO3, MgO and c-ZrO2) present in different volume fractions and grain size have been analysed. The hardness and Young´s modulus of each phase determined by nanoindentation are independent from the specific composite and coincident with nanoindentation values for single phase bulk materials. The contribution of the individual phases to Young´s modulus of the multiphase materials is in agreement with calculations using the nanoindentation values and the Voight upper limit of the “rule of mixtures”. Scale dependence due to microcracking has been observed for microhardness values of the composites and differences between calculations and experimental values are related to this effect., This work was performed in the frame of the CYTEDnetwork HOREF(312RT0453)and was supported by the Spanish Government underprojectMAT2013-48426-C2-1-R.AbílioP.Silvaacknowledges thefinancialsupportofJECSTrustthroughmobilityContract201597 and Instituto de Cerámica y Vidrio–CSIC.

The wear behaviour of a fine grained and dense CaZrO3-MgO composite is presented. Un-lubricated Pin-on-disc tests at room temperature have been performed using 10 N as normal force and 0.10–0.15 ms-1 as sliding rate and ZrO2 and steel counterparts. The coefficient of friction versus the sliding distance and the specific wear, together with a complete microstructural analysis of the worn surfaces by field emission scanning electron microscopy is reported. The composite presents a wear resistance similar to other ceramics under ceramic/ceramic sliding contact and improved wear resistance in contact with steel. Initial wear is dominated by abrasion independently of the chemical nature of the counterpart. The second stage wear depends on the characteristics of the third body formed. Zirconia leads to a brittle particulate third body with little protective capability. Steel forms a strongly bonded and plastic cermet third body that protects the material limiting the level of further wear. Fil: Silva, Abílio. Instituto de Ceramica y Vidrio de Madrid; España. Universidade Beira Interior; Portugal Fil: Booth, Raul Fernando Nicolas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina. Instituto de Ceramica y Vidrio de Madrid; España Fil: Garrido, Liliana Beatriz. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Aglietti, Esteban Fausto. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Pena, Pilar. Instituto de Ceramica y Vidrio de Madrid; España Fil: Baudín, Carmen. Instituto de Ceramica y Vidrio de Madrid; España

Processing and properties of two fine grain and dense CaZrO3-MgO based composites obtained by reaction sintering of pure ZrO2 and dolomite (CaMg(CO3)2) are described. Two dolomites with different levels of impurities were used to fabricate the materials: high purity (impurity content ≈1.2 wt.%, material DBZ) and impure dolomite (impurity content ≈6.12 wt.%, material DNZ). Mixtures (molar 1:1) were attrition milled and the reaction and sintering processes were studied using dynamical techniques (DTA-TG and dilatometry). Adequate sintering schedule was selected using the controlled sintering technique. The role of impurities on the physical characteristics, microstructure and mechanical properties of the obtained composites was analysed. Noticeable changes in microstructure, porosity, grain size and phases, were observed as function of final sintering temperature at 1350, 1400, 1450 °C, and impurity content. The obtained microstructures are discussed on the basis of the phase equilibrium relationships. Fil: Booth, Raul Fernando Nicolas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina. Instituto de Ceramica y Vidrio de Madrid; España Fil: Garrido, Liliana Beatriz. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Aglietti, Esteban Fausto. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Silva, Abílio. Instituto de Ceramica y Vidrio de Madrid; España. University of Beira Interior; Portugal Fil: Pena, Pilar. Instituto de Ceramica y Vidrio de Madrid; España Fil: Baudín, Carmen. Instituto de Ceramica y Vidrio de Madrid; España

CaZrO3 -MgO ceramics are useful as refractories in kilns for the cement production. One method of manufacture of such ceramics is by sintering from m-ZrO2 and dolomite MgCa(CO3)2 mixtures. In this work electrofused m-ZrO2 grains (fraction 3 agglomerates of variable size (~100µm) and MgO grains (size 2 grains. The elastic modulus and flexural strength were correlated with the presence of impurities of the dolomite, porosity and microstructure of the ceramic., Centro de Tecnología de Recursos Minerales y Cerámica, Facultad de Ciencias Exactas