A chip oxygen sensor with two-part zirconia structure and its preparation method

Abstract

The invention discloses a sheet-shaped oxygen sensor, which is formed by a porous protection layer, a function layer, an air cavity layer, a structure layer and a heating layer through sequential stacking and sintering from top to bottom, wherein one end of the porous protection layer is provided with a porous alumina substrate; the other end of the porous protection layer is provided with a firstalumina substrate; the function layer comprises a first zirconia substrate, an inner electrode and an outer electrode; the outer electrode is positioned at one side, near the porous protection layer,on the first zirconia substrate; the air cavity layer comprises a second alumina substrate and an air cavity formed above the second alumina substrate; the structure layer comprises a second zirconiasubstrate, a third alumina substrate and a fourth alumina substrate in sequential stacking from top to bottom; the heating layer comprises a fifth alumina substrate and a heater arranged above the fifth alumina substrate. The invention also provides a preparation method of the sheet-shaped oxygen sensor. Through the structure and formula design, bending and layering are eliminated; the finished product rate of the sheet-shaped oxygen sensor is improved; the service life of the sheet-shaped oxygen sensor is prolonged; the preparation process is simplified.

Description

technical field [0001] The invention relates to the technical field of sensors, in particular to a chip oxygen sensor with a two-part zirconia structure and a preparation method thereof. Background technique [0002] The oxygen sensor is used to detect the oxygen content in the exhaust gas of the automobile, and feed it back to the electronic control unit (ECU) of the automobile in the form of an electrical signal. Optimum combustion state) as the goal of closed-loop control. Among them, the chip oxygen sensor has become the mainstream product for detecting the oxygen content in automobile emissions due to its small size, fast response, low energy consumption, integrated heater, and long-term stable work in harsh environments. [0003] The operating temperature of the chip oxygen sensor is generally around 700°C, so the sensor needs to provide a voltage to the heater to make it work normally and stably. The traditional chip oxygen sensor is mainly based on a full zirconia s...

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Problems solved by technology

This process needs to add a screen printing process, that is, the zirconia needs to be printed on the insulating layer first, then the heater is printed on the printed insulating layer, and finally the insulating layer is printed on the heater to ensure that the heater is completely covered by the insulating layer. Wrapping, which undoubtedly increases the complexity of the process; at the same time, the insulating paste has no adhesion, which can easily lead to delamination of the heating layer after sintering, which affects the yield; and the thermal conductivity of zirconia is low, and repeated use will cause greater internal thermal stress And cracks appear, causing the sensor to fail

[0004] In order to avoid the above problems, a chip oxygen sensor with a composite structure of zirconia and alumina has appeared, but the thermal expansion coefficients of different material layers are different. During the use of the oxygen sensor, due to the constant heating and cooling, the sensor cannot withstand such conditions. Thermal fatigue, which leads to failure phenomena such as bending, delamination or cracking of the substrate during use

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