| With its unique advantages,hydrogen has been widely used in aerospace,energy,national defense and chemical industry.However,as a very dangerous gas,the hydrogen has the characteristics of the high explosive energy of the explosion limit,high explosive energy,and hydrogen is colorless and tasteless.Once the leakage occurs,there will be a major safety accident.With the increasing demand for industrial applications,it is becoming increasingly important for safe use of hydrogen,and the need for sensing devices with rapid and effective detection of hydrogen concentration is increasing.The optical fiber sensor has the advantages of strong anti-interference,high security and long distance transmission,so the application of optical fiber sensor to the detection of hydrogen concentration is very promising.There is no one can satisfy the industrial application of high performance optical fiber hydrogen sensor,the main problems include sensing material aging failure response,the curve of zero offset and sensing system robustness,etc.Therefore in order to solve the above problems,this article study the hydrogen diffusion model in the palladium,Light model of light through the optical sensing material and film failure causes,builds a palladium nanoparticles sensitization based transmission optical fiber hydrogen sensor experimental platform.The main research work is as follows:(1)For spherical palladium nanoparticles in different particle size under the condition of different temperatures and different concentration of hydrogen for hydrogen response relationship,using the second Fick’s law presents a globular palladium nanoparticles on the hydrogen diffusion model.Using the Mie scattering theory to establish the scattering model of the light wave through palladium nanoparticles,and the scattering model was solved by Rayleigh approximation and numerical method,and the light intensity distribution was obtained through the particle.(2)According to the hydrogen diffusion model of palladium nanoparticles,this paper designed a kind of ALD(atomic layer deposition)method preparation of discrete palladium nanoparticles film preparation technology,using(7)(8)5 6 22 Pd C HF O and formaldehyde(37% aqueous solution of formaldehyde)as precursor of ALD,the pure palladium nanoparticles was obtained through 800 pulse cycles.At the same time,this paper presents the design idea of using the palladium nanoparticles as the original sensor of transmission fiber hydrogen sensor.(3)The reason of the failure of the continuous thin film was analyzed by XPS.Thus,put forward using pure palladium nanoparticles film as a hydrogen sensitive film,then solve the yttrium palladium alloy membrane is the problem of oxygen poison in the air,effectively avoid film blister cracking phenomenon of zero drift.(4)The structure of a multi-layer transmission hydrogen fiber optic sensor is proposed,which can effectively enhance the signal-to-noise ratio of hydrogen response signal by utilizing the performance advantages of nanoparticles.At the same time,the influence of external factors such as light source drift on the sensor system is offset by using double-light road compensation in the sensor design.(5)The palladium nanoparticles sensitization based transmission optical fiber hydrogen sensor test platform was established,which tests the palladium nanoparticles on the platform of hydrogen response,the discrete of nanometer film hydrogen response time and recovery time were obtained,and the results showed that the membrane can effectively avoid the phenomenon of zero drift.The test of different layers of sensing film was carried out,and the number of layers and the response amplitude were basically linear,so increasing the number of sensing film layers could effectively strengthen the sensing signal strength.The response of the sensing thin film under the condition of low concentration of hydrogen was tested,and the results showed that the nanoparticles had a better response curve for low hydrogen concentration. |
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