Use of lanthanum chromite for making electric heaters

Abstract

According to [1, 2], alkaline-earth modified lanthanum chromite with n-type conductivity can be used to make resistance heater elements capable of operating in an oxidizing medium up to 1800-1850~In our work on the manufacture of heaters, we used fused material obtained by a procedure developed in the Lebedev Physical Institute, Academy of Sciences of the USSR [3, 4] and described in [5]. The mixture for synthesis of calcium oxide-modified lanthanum chromite contained lanthanum oxide of LaO-1 grade according to TU 48-4-184-72 (purity not less than 99.849 wt.%), calcium oxide of OKhM-1 grade according to GOST 2912-73 (Cr20 a content 98 wt.%), and CaCO 3 of analytical reagent grade according to GOST 4530-66.The fused block was subjected to x-ray phase, petrographic, quantitative x-ray spectral, and x-ray structural analysis. The diffraction patterns of specimens from different sectors of the block show considerable redistribution of the intensities of the principal reflections in comparison with the distribution in the standard (Fig. 1). This indicates the presence of microstresses in the lattice of the solid solution obtained, or of impurities in the material; this is improbable.Petrographic analysis revealed a certain nonuniformity of the solid solution, noted during dark-field analysis and indicating the nonequilibrial state of the material. This is apparently due to incomplete homogenizatton of the melt during fusion and subsequent crystaUization, and to quenching of high-temperature

High‐Temperature Electrical Conductivity of LaCr1−xCoxO3 Ceramics

“…Small polaron hopping associated with the chromium 3d band 3,4 gives rise for p-type semiconductivity of LaCrO 3 dominating over a wide range of oxygen partial pressure from 2.1 9 10 4 to 10 À17 Pa at 1000°C. 5 Distinguished by a superior high-temperature chemical stability in a wide range of oxygen partial pressures combined with a high electrical conductivity on the order of 10 À3 to 10 1 S/cm, lanthanum chromite-based ceramics gained interest for a variety of high-temperature electrochemical applications including interconnector in solid oxide fuel cell, 6 heating element, 7 hot electrode for magnetohydrodynamic power generation 8 and oxygen separator membrane. 9 Formation of lanthanum chromite solid solutions was widely investigated in order to stabilize phase modification, to optimize sintering behavior, to modify ion transport properties, and to tailor electrical properties.…”

Cromito de lantânio: material para interconectores de células a combustível de óxido sólido - uma revisão

“…Devido às suas características intrínsecas, o cromito de lantânio torna-se adequado para aplicações como interconector em células a combustível de óxido sólido [23,[64][65][66][67], geradores magneto hidrodinâmicos (MHD) [68][69][70], catalisadores para queima de combustíveis [71][72][73], sensores de NO X em alta temperatura [74], resistências para fornos [75,76] e sensor potenciométrico de oxigênio [77]. Ainda na geração de energia, pode ser utilizado como ânodo para células de óxido sólido de temperatura intermediária (ITSOFC) [78][79][80][81][82][83].…”

Tape casting of strontium and cobalt doped lanthanum chromite suspensions

“…Because of these properties, this material is used as solid oxide fuel cell interconnector (SOFC), 1-3 magneto hydrodynamic generators (MHD), 4,5 catalysts for soot combustion, 6,7 high temperature NO x sensors 8 and electric heaters. 9 In power generation field, doped lanthanum chromite is also used as anode for intermediate temperature solid oxide fuel cells (ITSOFC). [10][11][12] The preparation of thin tapes of lanthanum chromite is required for many of these applications.…”