Combustion synthesis and properties of mullite-zirconia composites

Chandran, Ramesh; Patil, K. C.; Chandrappa, G. T.

doi:10.1007/bf01160827

Cited by 9 publications

(17 citation statements)

References 18 publications

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“…However, a crystalline phase composed of zircon is also formed in such ceramics as a by-product [6]. The mullite-zirconia ceramic's apparent density and its degree of sintering vary in relation to the proportions of the crystalline phases that are formed and the sintering temperature [6].…”

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“…As a result, the mullite and mullite-zirconia powders that are obtained are characterized by rapid crystallization of the mullite phase and the tetragonal phase of ZrO 2 , the formation of moderate-sized and coarse pores (up to 85 mm), and the presence of fine (10 -35 mm) particles [6,8,12]. Agglomerates consisting of sintered particles are also formed in the mullite-zirconia powder [7,9,12].…”

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“…The formation of dense ceramic specimens during sintering from powders obtained by the combustion method is related to the diffusion of substances into the pores that were formed during the decrease in the powder's density, the filling of the pores with these substances, and the reactivity of the particles formed as the powder disintegrates [6,7,12].…”

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“…Powders with the properties described above can be obtained by regulating the proportions of metal nitrate (oxidant) and fuel [6,7] and by using a strongly exothermic fuel [7,9], an active external oxidant [10 -12], and excess fuel [12].…”

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Properties of a Mullite-Zirconium Ceramic Sintered by the Traditional Method from Powders Obtained During Combustion

Hmelov

2015

Refract Ind Ceram

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Results are presented from a study of the growth of the crystalline phases, the size distribution of the pores, and the size distribution of the particles that make up the powders. The powders were obtained by a water-based combustion method with the use of a mix containing solutions of nitrates of metals, SiO 2 (aerosil), an oxidant, and different fuels. The article reports results obtained from the formation of the crystalline phases and data on the pore-size distribution, apparent density, degree of sintering, and physico-mechanical properties of specimens sintered from the powders by the conventional method in the range 1300 -1500°C with and without the use of a clay addition. The powders formed by the combustion of carbamide and limonic acid are characterized by developed mullitization and crystallization of the tetragonal phase of ZrO 2 , the formation of coarse and relatively coarse pores, and the formation of fine and moderate-sized particles. The specimens sintered from such powders in the range 1300 -1500°C with a clay addition are characterized by developed crystallization of the phases and maximum values for apparent density, degree of sintering, and the indices of the physico-mechanical properties. These results stand in contrast to the results obtained for the specimens sintered from similar powders without clay and specimens sintered from clay and powders obtained by the combustion of glucose and saccharose.Producing finely dispersed initial powders with a narrow particle-size distribution and a developed surface area is currently the key to improving the phase composition, apparent density, degree of sintering, and physico-mechanical properties of mullite-zirconia ceramics [1, 2]. Powders of this type can be obtained by infiltration [2, 3] and by modern (non-traditional) methods of synthesis such as sol-gel synthesis [4], hydrothermal synthesis, and combustion [6 -8].The properties of the powders obtained by these methods are controlled by controlling the conditions which exist during the synthesis process [4 -8].In all of the above-mentioned chemical methods of producing mullite and mullite-zirconia powders, during combustion the phases that are formed in the powder crystallize, the product's density decreases (pores are formed in it), and the powders begin to disintegrate [6 -8].Powders with the properties described above can be obtained by regulating the proportions of metal nitrate (oxidant) and fuel [6,7] and by using a strongly exothermic fuel [7,9], an active external oxidant [10 -12], and excess fuel [12].As a result, the mullite and mullite-zirconia powders that are obtained are characterized by rapid crystallization of the mullite phase and the tetragonal phase of ZrO 2 , the formation of moderate-sized and coarse pores (up to 85 mm), and the presence of fine (10 -35 mm) particles [6,8,12]. Agglomerates consisting of sintered particles are also formed in the mullite-zirconia powder [7,9,12].The formation of dense ceramic specimens during sintering from powders obtained by the combustion ...

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Properties of a Mullite-Zirconium Ceramic Sintered by the Traditional Method from Powders Obtained During Combustion

Hmelov

2015

Refract Ind Ceram

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“…All these techniques require special chemicals and equipments and have various disadvantages. However, the low-temperature-initiated solution combustion process is an attractive synthetic route for the preparation of multi-component oxide materials, developed by Patil et al [11][12][13]. This method, in fact, makes possible the rapid synthesis of several refractory inorganic materials and advanced ceramics, without the prolonged high-temperature treatment of sintering.…”

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Magnetoresistive studies on nanocrystalline La0.8Sr0.2MnO3+δ manganite

Nagabhushana¹,

Chakradhar²,

Ramesh³

et al. 2008

Physica B: Condensed Matter

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a b s t r a c tLow-temperature magnetoresistance (MR) measurement has been carried out on nanocrystalline La 0.8 Sr 0.2 MnO 3+d manganites prepared by combustion synthesis. This preparation method yields voluminous powders with large surface area ($40 m 2 /g) having crystalline nanosize ($50 nm) products. Formation and homogeneity of the solid solutions have been confirmed by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Rietveld refinement of X-ray data indicates that as-formed compound exhibits cubic phase with space group Pm3 m. However, calcined sample transforms into rhombohedral phase with space group R-3c. The stabilization of the cubic phase in as-formed manganite is due to the substitution of Sr 2+ on La 3+ sites, resulting in higher Mn 4+ content. The low-temperature resistivity measurements down to 70 K exhibit a broad metal-insulator transition (T MÀI ) at around 257 K. MR measurements on sintered pellets show $5% MR at 1 T, whereas for 4 and 7 T, the %MR values are found as 22% and 28%, respectively, at T MÀI .

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Combustion Derived Nanocrystalline‐ZrO₂ and Its Catalytic Activity for Biginelli Condensation under Microwave Irradiation

et al. 2011

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Nanocrystalline zirconium(IV) oxide (nc-ZrO 2 ) possessing high surface area was synthesized by a low temperature eco-friendly solution combustion method using a new organic fuel alanine. The powder XRD, SEM and surface area measurements were carried out for characterization of nc-ZrO 2 . The powder XRD results revealed that, the nc-ZrO 2 has the pure tetragonal phase. The crystallite size calculated by Scherrer's formula and BET surface area were found to be ca. 53-57 nm and ca. 275 m 2 /g, respectively. SEM micrograph exhibited the macroporous nature of the powder. nc-ZrO 2 has been employed as a catalyst for the solvent-free synthesis of 3,4-dihydropyrimidin-2-ones (DHPMs) by a microwave (MW) assisted one-pot, multicomponent Biginelli condensation reaction of araldehydes, ethylacetoacetate and urea or thiourea. DHPMs are obtained in good to excellent yields (85%-96%) under this reaction condition within short interval of time (10-20 min).

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Combustion synthesis and properties of mullite-zirconia composites

Cited by 9 publications

References 18 publications

Properties of a Mullite-Zirconium Ceramic Sintered by the Traditional Method from Powders Obtained During Combustion

Properties of a Mullite-Zirconium Ceramic Sintered by the Traditional Method from Powders Obtained During Combustion

Magnetoresistive studies on nanocrystalline La0.8Sr0.2MnO3+δ manganite

Combustion Derived Nanocrystalline‐ZrO₂ and Its Catalytic Activity for Biginelli Condensation under Microwave Irradiation

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Combustion synthesis and properties of mullite-zirconia composites

Cited by 9 publications

References 18 publications

Properties of a Mullite-Zirconium Ceramic Sintered by the Traditional Method from Powders Obtained During Combustion

Properties of a Mullite-Zirconium Ceramic Sintered by the Traditional Method from Powders Obtained During Combustion

Magnetoresistive studies on nanocrystalline La0.8Sr0.2MnO3+δ manganite

Combustion Derived Nanocrystalline‐ZrO2 and Its Catalytic Activity for Biginelli Condensation under Microwave Irradiation

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Combustion Derived Nanocrystalline‐ZrO₂ and Its Catalytic Activity for Biginelli Condensation under Microwave Irradiation