Propriedades reológicas de matérias-primas do Pólo Cerâmico de Santa Gertrudes provenientes da Formação Corumbataí (região de Rio Claro, SP)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Si3N4 ceramic cutting tool sintered with CeO2 and Al2O3 additives with AlCrN coating

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of ceramic surface conditioning and resin cements on microtensile bond strength to a glass ceramic

Statement of problem. It is not clear how different glass ceramic surface pretreatments influence the bonding capacity of various luting agents to these surfaces.Purpose. The purpose of this study was to evaluate the microtensile bond strength (mu TBS) of 3 resin cements to a lithia disilicate-based ceramic submitted to 2 surface conditioning treatments.Material and methods. Eighteen 5 X 6 X 8-mm ceramic (IPS Empress 2) blocks were fabricated according to manufacturer's instructions and duplicated in composite resin (Tetric Ceram). Ceramic blocks were polished and divided into 2 groups (n=9/treatment): no conditioning (no-conditioning/control), or 5% hydrofluoric acid etching for 20 seconds and silanization for 1 minute (HF + SIL). Ceramic blocks were cemented to the composite resin blocks with I self-adhesive universal resin cement (RelyX Unicem) or 1 of 2 resin-based luting agents (Multilink or Panavia F), according to the manufacturer's instructions. The composite resin-ceramic blocks were stored in humidity at 37 degrees C for 7 days and serially sectioned to produce 25 beam specimens per group with a 1.0-mm(2) cross-sectional area. Specimens were thermal cycled (5000 cycles, 5 degrees C-55 degrees C) and tested in tension at 1 mm/min. Microtensile bond strength data (MPa) were analyzed by 2-way analysis of variance and Tukey multiple comparisons tests (alpha=.05). Fractured specimens were examined with a stereomicroscope (X40) and classified as adhesive, mixed, or cohesive.Results. The surface conditioning factor was significant (HF+SIL > no-conditioning) (P<.0001). Considering the unconditioned groups, the mu TBS of RelyX Unicem was significantly higher (9.6 +/- 1.9) than that of Multilink (6.2 +/- 1.2) and Panavia F (7.4 +/- 1.9). Previous etching and silanization yielded statistically higher mu TBS values for RelyX Unicem (18.8 +/- 3.5) and Multilink (17.4 +/- 3.0) when compared to Panavia F (15.7 +/- 3.8). Spontaneous debonding after thermal cycling was detected when luting agents were applied to untreated ceramic surfaces.Conclusion. Etching and silanization treatments appear to be crucial for resin bonding to a lithia disilicate-based ceramic, regardless of the resin cement used.

Barrier and Mechanical Properties of Clay-Reinforced Polymeric Nanocomposites

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Microtensile bond strength of a resin cement to glass infiltrated zirconia-reinforced ceramic: The effect of surface conditioning

This study evaluated the effect of three surface conditioning methods on the microtensile bond strength of resin cement to a glass-infiltrated zirconia-reinforced alumina-based core ceramic. Thirty blocks (5×5×4 mm) of In-Ceram Zirconia ceramics (In-Ceram Zirconia-INC-ZR, VITA) were fabricated according to the manufacturer's instructions and duplicated in resin composite. The specimens were polished and assigned to one of the following three treatment conditions (n=10): (1) Airborne particle abrasion with 110 μm Al2O3 particles + silanization, (2) Silica coating with 110 μm SiOx particles (Rocatec Pre and Plus, 3M ESPE) + silanization, (3) Silica coating with 30 μm SiOx particles (CoJet, 3M ESPE) + silanization. The ceramic-composite blocks were cemented with the resin cement (Panavia F) and stored at 37 °C in distilled water for 7 days prior to bond tests. The blocks were cut under coolant water to produce bar specimens with a bonding area of approximately 0.6 mm2. The bond strength tests were performed in a universal testing machine (cross-head speed: 1 mm/min). The mean bond strengths of the specimens of each block were statistically analyzed using ANOVA and Tukey's test (α≤0.05). Silica coating with silanization either using 110 μm SiOx or 30 μm SiOx particles increased the bond strength of the resin cement (24.6±2.7 MPa and 26.7±2.4 MPa, respectively) to the zirconia-based ceramic significantly compared to that of airborne particle abrasion with 110-μm Al2O3 (20.5±3.8 MPa) (ANOVA, P<0.05). Conditioning the INC-ZR ceramic surfaces with silica coating and silanization using either chairside or laboratory devices provided higher bond strengths of the resin cement than with airborne particle abrasion using 110 μm Al2O3. © 2005 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Properties advanced of the silicon nitride based ceramics and recent performance on automotive parts manufacture by machining process: Advanced Ceramics, demand Forecast

Automotive parts manufacture by machining process using silicon nitride-based ceramic tool development in Brazil already is a reality. Si 3N4-based ceramic cutting tools offer a high productivity due to their excellent hot hardness, which allows high cutting speeds. Under such conditions the cutting tool must be resistant to a combination of mechanical, thermal and chemical attacks. Silicon nitride based ceramic materials constitute a mature technology with a very broad base of current and potential applications. The best opportunities for Si3N 4-based ceramics include ballistic armor, composite automotive brakes, diesel particulate filters, joint replacement products and others. The goal of this work was to show latter advance in silicon nitride manufacture and its recent evolution on machining process of gray cast iron, compacted graphite iron and Ti-6Al-4V. Materials characterization and machining tests were analyzed by X-Ray Diffraction, Scanning Electron Microscopy, Vickers hardness and toughness fracture and technical norm. In recent works the authors has been proved to advance in microstructural, mechanical and physic properties control. These facts prove that silicon nitride-based ceramic has enough resistance to withstand the impacts inherent to the machining of gray cast iron (CI), compacted graphite iron (CGI) and Ti-6Al-4V (6-4). Copyright © 2008 SAE International.

Análise comparativa do ambiente de aviários de postura com diferentes sistemas de acondicionamento

Poulty house typology and the materials used (mainly for roofing) are the determining factors for an appropriate thermal condition aiming at production. In this context, the main point of this paper was to identify differences in the internal environment of two poultry houses, using monitoring and afterwards using statistics for comparing the environmental variables. The data analyzed did not show evidence of better thermal comfort for the house which was covered with ceramic roofing tile, because this house did not have ridged vents, making the hot air exit from the house difficult by the chimney effect. The ammonia concentration measured inside both houses was within the comfort limit. The temperature and humidity index of the house covered with ceramic roofing tiles was higher than the house which was covered with cement asbestos roofing tile, even though lower temperature on the tiles' surfaces was verified, showing the positive effects of the use of ridge vents at the housing. Based on the results obtained it is recommended for the Bastos, SP region, that poulty houses should be built with the ridge vent and long eaves beyond the roof of ceramic tiles.

Alterações hidrogeomorfológicas devido à dinâmica de uso da terra na Bacia Hidrográfica do Ribeirão Santa Gertrudes (SP)

Agricultural and mining activities are directly related to changes in natural landscapes. From the perspective of anthropogenic geomorphology supported by general systems theory, this research has developed, in order to identify and analyze changes in the land use, mainly from agriculture and the exploitation of clay, and its implications in the hydro-geomorphological characteristics in the Santa Gertrudes Stream watershed (SP). This area is within the context of the Ceramic Pole Santa Gertrudes (SP), which besides its importance as a supplier of raw material, is characterized as the largest center of international reference in ceramic tiles on the American continent. For this purpose, we made land use and geomorphology maps of two scenarios, corresponding to the years 1962 and 2006, which allowed the identification of changes caused by human activities on the landforms of the area, such as the increase in area of parcels intended for mining activity, which went from 3.1% to occupy 19% of the catchment area of the respective period and that, among other changes, gave rise to new forms of relief as, for example, in levels of pit mining abrupt and smooth. The results indicate that the main features of representative of human changes in relief are represented for opening of large clay mining pits and agricultural activities, which intensified the denudation and sedimentation processes in the Santa Gertrudes Stream watershed.

Effect of seating forces on cement-ceramic adhesion in microtensile bond tests

Objectives: The aim of this study was to evaluate the effect of different seating forces during cementation in cement-ceramic microtensile bond strength (μTBS). Materials and methods: Forty-five blocks (5 × 5 × 4 mm3) of a glass-infiltrated alumina-based ceramic (In-Ceram Alumina) were fabricated according to the manufacturer's instructions and duplicated in resin composite. Ceramic surfaces were polished, cleaned for 10 min in an ultrasonic bath, silica coated using a laboratory type of air abrasion device, and silanized. Each treated ceramic block was then randomly assigned to five groups (n = 9) and cemented to a composite block under five seating forces (10 g, 50 g, 100 g, 500 g, and 750 g) using a dual-cured resin cement (Panavia F). The ceramic-cement-composite assemblies were cut under coolant water to obtain bar specimens (1 mm × 0. 8 mm2). The μTBS tests were performed in a universal testing machine (1 mm/min). The mean bond strengths values were statistically analyzed using one-way ANOVA (α ≤ 0. 05). Results: Different seating forces resulted in no significant difference in the μTBS results ranging between 13. 1 ± 4. 7 and 18. 8 ± 2. 1 MPa (p = 0. 13) and no significant differences among cement thickness. Conclusions: Excessive seating forces during cementation seem not to affect the μTBS results. Clinical relevance: Excessive forces during the seating of single all-ceramic restorations cementation seem to display the same tensile bond strength to the resin cement. © 2012 Springer-Verlag.

Caracterização geoquímica e cerâmica das argilas do Grupo Itacaré / Formação Aquidauana, na faixa aflorante entre os estados de São Paulo e sul de Minas Gerais

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Argilas da formação Corumbataí como base para obtenção de grés porcelanato por via seca

Pós-graduação em Geologia Regional - IGCE

Petrologia aplicada da formação Corumbataí (região de Rio Claro - SP) e produtos cerâmicos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Utilização do lodo de estação de tratamento de efluentes da indústria de injeção plástica como matéria-prima para indústria cerâmica

A indústria de injeção plástica é de fundamental importância para a economia nacional, pois é responsável pela produção de insumos primários para várias indústrias de eletroeletrônicos. Estas empresas geram efluentes procedentes das unidades de pintura por jateamento e aspersão. Este resíduo necessita de tratamento especial para sua separação, armazenagem e destino final. Este trabalho estuda uma forma alternativa de utilização deste resíduo na indústria de cerâmica vermelha, avaliando parâmetros que influenciam em propriedades importantes nos artefatos fabricados com argila vermelha como: densidade, porosidade e resistência à flexão, avaliados para misturas de 2%, 5% e 10% em peso de resíduo, em relação a argila utilizada, os resultados mostram que há influência deste material nas reações de estado sólido podendo haver melhora nas propriedades citadas.

Síntese e caracterização estrutural de pigmentos cerâmicos a base de cromita por método químico

The ceramic pigments are colored inorganic substances that during the process of dispersion in the ceramic glazes and subsequent calcination, are stable against physical and chemical attack. Therefore, they are crystalline compounds applied in the ceramic industry for coloring vitreous base. In this study, the Pechini method was used for obtaining the pigment CuCr2O4 with heat treatment at the temperatures of 800, 900 and 1000 ° C. The powder pigments were characterized on their structural, morphological and colorimetric aspects. The thermal analysis conducted on an amorphous precursor in a TG / DTA indicates the weight loss in the entire temperature range investigated, with characteristic exothermic peak of the elimination of the organic composition of the precursor around 300°C. The development of the crystalline phases were investigated by XRD, using a diffractometer with Cu Ka radiation and graphite monochromator, where it was observed the presence of crystalline phases corresponding to Cr2O3 and CuCr2O4.The measurements of the specific surface area of the powders pigments were carried out in an equipment Micromeritcs, model ASAP 2000, using N2 as gas of adsorption/desorption. The colorimetric measurements of the pigments were made in a colorimeter Gretac Macbeth Color-eye spectrophotometer 2180 / 2180UV in CIELAB standards. Based on the obtained results, it can be verified the thermal stability of the powder pigments of green coloration, which enables it as an alternative to the materials currently used in the manufacture of ceramic tiles.

SnO2 dense ceramic microwave sintered with low resistivity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)