A sealing glass-ceramic and its preparation and use method

Abstract

The invention discloses a sealing glass ceramic as well as a preparation and use method thereof. The sealing glass ceramic comprises raw materials B2O3, Al2O3, SiO2, Mo (one substance or a mixture of multiple substances of MgO, CaO, SrO and BaO) and NiO based on the molar ratio of (0-10): (0-5): (25-60): (20-50): (5-30). According to the preparation method, NiO is added, so that the generation of the glass ceramic is promoted, the diffusion of Cr ions to the sealing glass in a Cr-containing stainless steel aluminum connection pole can be effectively reduced, and the chemical stability of the sealing glass ceramic under high temperature is obviously improved; and in addition, the NiO obviously lowers the sealing temperature of the glass, so that other elements can be prevented from being damaged by the high temperature. The preparation method is simple in raw materials for preparing, available in raw materials, stable in process, capable of obtaining an invert glass network structure with SiO2 as a main body, low in cost, simple and feasible in process, and reaches the practical and industrial conditions.

Description

technical field [0001] The invention belongs to the field of solid oxide fuel cells, and in particular relates to a sealing glass-ceramic with high-temperature chemical stability and its preparation and use. Background technique [0002] Solid oxide fuel cell (SOFC) adopts solid oxide (ceramic) electrolyte, operates at high temperature, has high power generation efficiency, low material cost, and is compatible with various fuels (such as methane, gas, methanol, alcohol, liquefied petroleum gas, etc. )Etc. However, the main problem facing the development of SOFC is how to effectively isolate and seal the fuel gas and oxidant gas at high temperatures. Due to the high operating temperature of the battery (700-750°C), the selection of suitable sealing materials and sealing technologies has become the key to restricting the development of planar SOFCs. In order to solve the problem of sealing failure between sealing materials and Cr-containing stainless steels, researchers at h...

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Problems solved by technology

In order to solve the problem of sealing failure between sealing materials and Cr-containing stainless steels, researchers at home and abroad have adopted: ① pre-oxidize the Cr-containing alloy joints to reduce the interface reaction between the sealing materials and Cr-containing alloys; The alloy connector is coated with a protective layer to limit the diffusion of Cr; ③ the interface reaction is controlled by improving the formula of glass ceramics, such as Loehman of Sandia National Laboratory in the United States also tried to add a saturated concentration of Cr to the glass matrix 2 o 3 To suppress the diffusion of Cr; ④Use alkali metal oxides (such as Na 2 O and K 2 O) to replace alkaline earth metal oxides that are prone to reactions, but none of the above methods can satisfactorily solve the problem of sealing failure caused by interfacial reactions

[0003] For the thermal expansion coefficient mismatch between the sealing material and other components (such as sealing glass 11~13×10 -6 / K, chromium-containing stainless steel alloy connector ~13×10 -6 / K) leads to the generation of thermal stress, and then induces the initiation and expansion of cracks, so that the final failure of the seal. Domestic and foreign research has devoted a lot of energy to the development of self-healing sealing materials that can maintain the glass state for a long time at high temperatures, trying to pass Viscous flow of the glass phase relieves thermal stress accumulated at the sealing interface

However, the network ligand ions (such as group IIA) used to improve the viscosity of the sealing glass react easily with the Cr-containing alloy linker at the working temperature of the SOFC, forming such as BaCrO 4 , SrCrO 4 and CaCrO 4 etc. have extremely high coefficient of thermal expansion (18~20×10 -6 / K), which again causes the thermal expansion coefficient mismatch with other components of the sealing interface, destroys the bonding force of the seal, and seriously restricts the service life of the sealing material and SOFC, especially the stability in the thermal cycle process.

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