Time filter

Source Type

Santa Catarina, Brazil

Kniess C.T.,Nove de Julho University | Kniess C.T.,Federal University of Santa Catarina | Martins G.J.M.,Federal University of Santa Catarina | Martins G.J.M.,Centro Universitario Barriga Verde | And 5 more authors.
Materials Science Forum | Year: 2015

The production of materials from crystallization of glass, called glassceramic, have proved interesting by the possibility of development of different microstructures, with reduced grain size and the presence of residual amorphous phase in different quantities. The method that uses the differential thermal analysis (DTA) provides research on the material properties over a wide temperature range, it´s widely applied to crystallization processes of glassceramic materials. Within this context, this paper aims to study the kinetics of nucleation and crystal growth in glassceramic materials in the system SiO2-Al2O3-Li2O, obtained with the addition of mineral coal bottom ash as source of aluminosilicates, through the technique of differential thermal analysis. © (2015) Trans Tech Publications, Switzerland. Source

Piva R.H.,Centro Universitario Barriga Verde | Vilarinho P.,University of Aveiro | Morelli M.R.,Federal University of Sao Carlos | Fiori M.A.,University of the Extreme South of Santa Catarina | Montedo O.R.K.,University of the Extreme South of Santa Catarina
Ceramics International | Year: 2013

Due to the increasing availability of substitute materials for electrical porcelain, research is needed to adapt formulations involving these materials to the current economic realities of the industry. This study assessed the effect of iron oxide concentration (0, 1, 2, 3, 5, and 8 wt%) on the dielectric properties of an aluminous porcelain composition commonly employed for electrical insulation based on different values of temperature and frequency. Samples with iron oxide contents of 0, 3, and 5 wt% were analyzed using dilatometry, X-ray diffraction, and scanning electron microscopy to evaluate the thermal, structural, and microstructural changes related to their Fe 2O3 concentrations. Both the dielectric constant (εr) and the loss tangent (tan δ) were measured and evaluated in every sample. Results indicated that the presence of Fe 2O3 increased the dielectric constant and loss tangent, which could result in an increase in heating by dielectric losses. Fe 2O3 contents of up to 5 wt% had no significant effect on the performance of these insulators at room temperature (∼30° C) and a high frequency (1 MHz), especially when the hematite phase was completely solubilized in the porcelain phases. © 2013 Elsevier Ltd and Techna Group S.r.l. Source

Cruz F.B.,Santa Catarina State University | Cruz F.B.,Centro Universitario Barriga Verde | Lohn L.,Santa Catarina State University | Marinho L.S.R.,Santa Catarina State University | And 6 more authors.
Animal Reproduction Science | Year: 2011

Bull breeding soundness evaluation (BBSE) usually neglects the libido and mating ability evaluation. The internal artificial vagina (IAV) permits semen sampling, as well as mating ability evaluation. Few studies have been performed using IAV with young bulls and there are none with Bos indicus bulls. The present study evaluated sexual behavior, mating ability and semen quality in young Bos taurus (Devon) and B. indicus (Nellore) bulls using the IAV device. In the first experiment, 52 Devon bulls, 18-25 months old were observed, and the behavior and mating ability recorded over a 10-min period within a restrained mount-cow with an IAV inserted. In the second experiment, 20 Nellore bulls, 20-30 months old were evaluated over a 20. min period. Of the 52 Devon bulls, 45 (86.5%) had semen recovered with the IAV, 31 (69.0%) were considered satisfactory. Nellore bulls exhibited a different sexual behavior, with 10 bulls not showing any interest in the females. Four bulls demonstrated sexual interest only once, e.g., sniffing, two showed interest on more than one occasion, and four had more than two mounts or mounting attempts. None out of the Nellore bulls was collected with IAV. The IAV was an effective and welfare-promoting animal technology for the evaluation of semen quality and mating ability of B. taurus bulls. However, the IAV was not adequate for young Nellore bulls, probably due to their quiescent sexual behavior and delayed sexual maturity. Further studies are needed to evaluate the performance of the IAV for older Nellore bulls. © 2011 Elsevier B.V. Source

Nandi V.S.,Federal University of Santa Catarina | Nandi V.S.,Centro Universitario Barriga Verde | Raupp-Pereira F.,Federal University of Santa Catarina | Montedo O.R.K.,University of the Extreme South of Santa Catarina | Oliveira A.P.N.,Federal University of Santa Catarina
Journal of Cleaner Production | Year: 2015

The aim of this work was the valorization of two wastes that are classified as Class I according to the Brazilian Standard ABNT NBR 10004:2004 in order to obtain a ceramic engobe for the production of single-fire ceramic tiles. Ceramic sludge from a wastewater treatment plant of a ceramic tile manufacturer and recycled glass were used to obtain a frit in order to make the sludge and glass inert in a vitreous matrix. Thus, a representative amount of the ceramic sludge was collected, dried, and characterized by chemical analysis, X-ray diffractometry, and thermal analyses (differential thermal analysis, thermogravimetric analysis, and dilatometric analysis). Furthermore, the ceramic sludge was assessed according to the ABNT NBR 10004:2004. Seven formulations containing ceramic sludge contents varying from 20 to 80 wt% and recycled glass contents varying from 12 to 48 wt% and using calcite, dolomite, ulexite, and saltpeter as raw materials were prepared. Each formulation was melted in a laboratory kiln using alumina crucibles at 1420 °C for 1 h, and the melts were poured into water at room temperature to produce frits. Each frit was milled, and the coefficient of thermal expansion was determined by dilatometry. The results show that the studied ceramic sludge presented high contents of barium and fluoride. The main identified crystalline phases were α-quartz, zircon, illite, and barium silicate. The coefficient of thermal expansion after heat treatment was 5.6 × 10-6 °C-1. Once characterized, the feasibility of applying these wastes as raw materials for the production of ceramic frits was evaluated. The results of the dilatometric analysis, glaze fluidity flow test, and visual analysis showed that the incorporation of these wastes would allow for the obtainment of ceramic frits for producing ceramic engobes. Thus, three formulations of engobe were prepared and heat-treated at 1150, 1165, and 1175 °C. The engobes were characterized (XRD, determination of brightness, colorimetry, and microstructural analysis by optical microscopy) and showed suitable properties for use in the production of ceramic tiles. Engobe E3, which presented the highest ceramic sludge content, was selected for an industrial test. The results of a visual analysis and water spot test showed that the investigated engobe, compared with a commercial engobe (engobe reference), could be used in the production of glazed ceramic tiles. © 2014 Elsevier Ltd. Source

Pozzobom I.E.F.,Federal University of Santa Catarina | Rodrigues-Neto J.B.,Federal University of Santa Catarina | Raupp-Pereira F.,Federal University of Santa Catarina | Donadel K.,Centro Universitario Barriga Verde | And 2 more authors.
Revista Materia | Year: 2014

In this work the viscosimetry technique was used to evaluate the rheological characteristics of ceramic suspensions prepared with a LZSA (Li2O-ZrO2-SiO2-Al2O3) glass. From the rheological characterization it was possible to establish optimized conditions of solid fraction, dispersant, organic monomers and foaming agent for the production of glass-ceramic foams by gelcasting. The resulting foams were subjected to heat-treatments at 200-500°C/60 min, for degradation of organics and at 950°C/60 min for sintering and crystallization. With the obtained porous ceramic bodies linear thermal shrinkage, apparent density and mechanical strength measurements as well as microstructural analysis were performed. The adaptation of the rheological characteristics of the LZSA parent glass powder with the gelcasting processing technique allowed the production of ceramic foams with high open and interconnected porosity (>90%) with good thermal stability and with mechanical strength suitable for the production of porous ceramics. © 2014 Universidade Federal do Rio de Janeiro. All rights reserved. Source

Discover hidden collaborations