A influência simultânea do teor de alumina, da porosidade total e da temperatura na condutividade térmica de refratários sílico-aluminosos e aluminosos

Akiyoshi, M. M.; Silva, M. G. da; Silva, A. P. da; Pandolfelli, V. C.

doi:10.1590/s0366-69132001000300007

Cited by 3 publications

(2 citation statements)

References 2 publications

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“…Thermal conductivity was determined using the hot wire surface technique. Several authors [38][39][40][41][42][43] have already corroborated that this technique is a variant of the hot wire parallel technique, which is characterized as being a direct method that detects the transient temperature. Fourier transform infrared spectroscopy (FTIR), using a spectrometer (FTIR-ATR, Perkin Elmer) in absorbance mode from 4000 to 400 cm -1 , was performed to verify the possible effects of the chemical composition on the geopolymerization reaction process.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of the properties of a foamed geopolymer developed with different types of metakaolin

et al. 2021

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The physical and mechanical properties of foamed geopolymers were determined. The geopolymers were made with two different metakaolins (from Metacaulim do Brasil -MB, and Pantano Grande/RS -MPG) as precursors, with NaOH and Na 2 SiO 3 as activators, and with the addition of foam, which was produced with the foaming agent diethanolamide of coconut fatty acid with a minimum of 80% concentration. Also, two times (2.5 and 4 h) were used for the calcination of MPG at 750 °C. The results showed that all factors (precursors type, alkali content, silica modulus, and foam content) had a significant influence on the response variables, which presented the following variations: compressive strength of 0.36 to 3.23 MPa; thermal conductivity from 0.22 to 0.42 W/(m.K); saturated bulk density from 1176 to 1364 kg/m 3 ; dry bulk density of 619 to 864 kg/m 3 ; air void from 46.4% to 62.5%; and water absorption from 55.7% to 95.4%. It was also concluded that the precursor type was the factor that had the most influence on the properties of foamed geopolymers, with MPG calcined for 4 h being the best, as greater compressive strength and low thermal conductivity were obtained.

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Section: Methodsmentioning

confidence: 99%

Evaluation of the properties of a foamed geopolymer developed with different types of metakaolin

et al. 2021

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“…Os ensaios foram realizados em uma máquina universal de ensaios mecânicos (Emic-DL 10000). A porosidade geométrica dos corpos foi calculada pela equação (B) [8].…”

Section: Caracterização Do Corpo Sólido De Gesso β (Caso 4 2h 2 O /unclassified

Caracterização química, mecânica e morfológica do gesso obtido do pólo do Araripe

2014

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O gesso é um sulfato de cálcio hemihidratado com fórmula química CaSO4.0,5H2O, este é produzido em grande abundância na região do Araripe estado de Pernambuco e apresenta uma pureza que varia de 80 a 95%, sua aplicação baseia-se principalmente na construção civil e em um segundo plano observa-se sua utilização na odontologia, industria química, ortopedia etc. Frente à elevada qualidade da matéria prima em questão e ao baixo emprego do gesso em materiais e objetos de maior valor agregado, verificou-se a necessidade da caracterização desta matéria prima para um maior conhecimento de suas propriedades, sendo realizadas para tal, análises de FTIR, DRX, FRX, MEV com EDS acoplado, ensaios mecânicos de resistência à compressão e à flexão, cálculo da porosidade geométrica dos corpos sólidos, análise granulométrica das partículas e avaliação do tempo de pega da pasta. Este estudo tem a finalidade de conhecer detalhadamente suas características químicas, morfológicas e mecânicas, para que então posteriormente tais informações possam ser válidas para estudos referentes ao melhoramento de suas propriedades visando sua aplicação em novos produtos.

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Thermal Conductivity of Porous Alumina-Zirconia Prepared by Foam Technique for Applications in Cooling Systems of Artificial Satellites

Hirschmann¹,

Nono²,

Silva

2010

MSF

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Porous ceramics are of great interest due to their numerous potential applications. The objective of the present investigation was to produce porous alumina with 3 mol % yttria-stabilized tetragonal zirconia (Y-TZP). This material will be used in cooling systems of satellites. To obtain the porous ceramics the direct foaming technique was used. This method is based on the preparation of a stable foam to which a slurry of alumina and zirconia is added. The mixture is then vigorously stirred for incorporation of air. The sintered ceramics were characterized by scanning electron microscopy, mercury porosimetry and thermal conductivity. The tests performed with the porous alumina-zirconia ceramic composite obtained by this method, showed low thermal conductivity values, high porosity and uniform microstructure with 20–100 µm open pores. The results show that the alumina-zirconia composites tested in this study have a potential for application in loop heat pipes of cooling systems of satellites.

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A influência simultânea do teor de alumina, da porosidade total e da temperatura na condutividade térmica de refratários sílico-aluminosos e aluminosos

Cited by 3 publications

References 2 publications

Evaluation of the properties of a foamed geopolymer developed with different types of metakaolin

Evaluation of the properties of a foamed geopolymer developed with different types of metakaolin

Caracterização química, mecânica e morfológica do gesso obtido do pólo do Araripe

Thermal Conductivity of Porous Alumina-Zirconia Prepared by Foam Technique for Applications in Cooling Systems of Artificial Satellites

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