Fiber bragg grating hydrogen sensing system based on amorphous palladium-based alloy and sensor

Abstract

The invention discloses a fiber bragg grating hydrogen sensing system based on amorphous palladium-based alloy. The fiber bragg grating hydrogen sensing system is formed by welding a first fiber bragggrating and a second fiber bragg grating which have different central wavelengths in series, wherein the surface of the second fiber bragg grating is coated with a sensing film layer to form a hydrogen sensitive probe, and the sensing film layer is an amorphous palladium-based alloy film. Byutilizing the principle that the stress and the refractive index are changed after the sensing film layer absorbs hydrogen, the hydrogen concentration in the environment is converted into the offset of the central wavelength of a substrate, and the material has both the reversible hydrogen absorption performance of metal palladium and the excellent hydrogen permeability of amorphous alloy, so that the stability and sensitivity of a sensing system can be greatly improved. The surface of the first grating is exposed and used for temperature measurement and temperature compensation, and the inherent temperature cross sensitivity problem of the fiber grating sensor is eliminated. Aiming at the type ofthe second grating, the invention further provides two sensors loading the hydrogen sensing system based on reflection and transmission spectra respectively.

Description

Technical field[0001]The invention belongs to the technical field of hydrogen sensors, and specifically relates to a fiber grating hydrogen sensing system based on an amorphous palladium-based alloy. The invention also relates to a method for preparing a hydrogen sensor loaded with the sensing system.Background technique[0002]As one of the most promising clean energy sources, hydrogen has the characteristics of diverse sources, clean and low-carbon, flexible and efficient, and may become the ultimate form of energy use in the future. It has been used in many fields, such as reducing agents and heat sources in the metallurgical industry, and fuel for fuel cell vehicles. However, hydrogen is a colorless and odorless gas with a low ignition energy (only 0.02 mJ at the lowest) and a large flame propagation speed. When the hydrogen content in the air is between 4.0% and 75%, it will To open flame or electric current, it is easy to explode. At the same time, due to its small molecular vol...

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Problems solved by technology

[0005] However, fiber gratings have the problem of cross-sensitivity between strain and temperature. In order to achieve high-precision measurement, it is usually necessary to perform temperature compensation on the fiber grating sensing system.

Patent CN105841840A proposes an optical fiber sensor capable of simultaneously measuring hydrogen gas concentration and temperature. Its essence is to realize simultaneous measurement of hydrogen gas concentration and temperature by monitoring the interference spectrum generated by the coreless fiber and the reflection spectrum generated by the Bragg grating. High loss and poor stability

Patent CN105572054A proposes a fiber-optic hydrogen sensor with temperature compensation function, which uses two Bragg gratings with the same parameters in series to eliminate temperature cross-sensitivity through the difference in the center wavelength drift of the two gratings, but the design of the same grating is different in temperature or hydrogen When the concentration change is not obvious, there is wavelength confusion, which leads to the disadvantage of decreased accuracy

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