Method for preparing dense diffusion barrier of limiting current type oxygen sensor with co-permeation method

Abstract

The invention belongs to the technical field of sensors, and particularly relates to a method for preparing a dense diffusion barrier of a limiting current type oxygen sensor with a co-permeation method. The method comprises steps as follows: La2O3, SrCO3, Ga2O3 and MgO are taken as raw materials, a La0.8Sr0.2Ga0.83Mg0.17O2.815 sheet is prepared with a solid-phase synthesis method, the La0.8Sr0.2Ga0.83Mg0.17O2.815 sheet is arranged at the lower part of a forming die, the upper part of the forming die is filled with transition metal oxide powder, pressure is kept for 5-10 min under the pressure intensity of 6-10 MPa, then sintering is performed for 5-50 h at the temperature of 1,400-1,600 DEG C, and after natural cooling, the dense diffusion barrier of the limiting current type oxygen sensor is obtained. The dense diffusion barrier prepared with the method is dense, uniform and pore-free in structure and firm in combination, the thermal expansion difference between a matrix and the dense diffusion barrier is reduced to the minimum, and the dense diffusion barrier has the advantages of short preparation period and high sensitivity.

Description

Technical field [0001] The invention belongs to the technical field of sensors, and specifically relates to a method for preparing a dense diffusion barrier layer of a limiting current type oxygen sensor by a co-permeation method. Background technique [0002] The furnaces of iron and steel metallurgical enterprises consume a lot of energy. In order to save energy and optimize the combustion of heating furnaces, it is necessary to strictly control the air-fuel ratio in the thermal system. Only a reasonable air-fuel ratio can achieve a higher combustion temperature and improve energy utilization. It is a direct and effective method to use the electrochemical oxygen sensor to detect the oxygen content in the furnace gas in real time and online. [0003] Electrochemical oxygen sensors are divided into concentration battery type and limiting current type. Compared with concentration battery type oxygen sensors, limiting current type oxygen sensors have a wide measuring range, short res...

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Problems solved by technology

Since LSM is easily reduced by C during the SPS sintering process, the thermal expansion coefficient mismatch between LSCM and YSZ causes cracking of the sintered body, so the oxygen measurement performance is not ideal

The so-called ceramic chip composite method is to use platinum paste to bond the sintered dense diffusion barrier layer and solid electrolyte, and then sinter the platinum paste to enhance the bonding performance of the two. This method avoids harmful chemical reactions between materials. And the crack phenomenon caused by the mismatch of thermal expansion coefficient, Liu Tao et al once used Sr 1–x Ho x CoO 3–δ is a dense diffusion barrier layer, with La 0.8 Sr 0.2 Ga 0.83 Mg 0.17 o 2.815 (LSGM) is a solid electrolyte, and the oxygen sensor is prepared by the ceramic chip composite method, which has good oxygen measurement characteristics. However, the preparation process of this method is cumbersome and the cycle is long, and the dense diffusion barrier layer prepared by the conventional sintering method contains many pores.

The heating and cooling speed in the process of preparation by laser cladding technology is extremely fast, and the maximum speed can reach 1012°C / s. Due to the difference in temperature gradient and thermal expansion coefficient between the cladding layer and the base material, multiple thermal expansions may occur in the cladding layer. defects, mainly including pores, cracks, deformation and surface roughness, and the control method of crack sensitivity of laser cladding layer is not yet mature

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