Research On The Uv Laser Cleaning Technology Of Surface Attachment Of Offshore Instruments

The protective layer on the surface of the offshore instrument is easily corroded and attached by microorganisms when it works in the seawater or the humid environment with salt for a long time,which affects the normal operation of the instrument and even damages it.Therefore,the surface of offshore instruments needs to be cleaned regularly.The traditional method is mainly chemical cleaning,which causes serious environmental pollution.Laser cleaning is a pollution-free,efficient and high-quality advanced cleaning technology,especially suitable for cleaning the surface of offshore instruments.However,infrared laser is usually used for laser cleaning at present,and the cleaning mainly depends on photothermal effect.If the laser energy injected on the surface is large,it is easy to cause thermal damage to the surface of the matrix,such as phase transformation and microcracks.Based on this,a UV laser cleaning method for surface attachments of offshore instruments is proposed in this paper.Due to the high energy of ultraviolet laser photons,there are both photothermal and photochemical effects when interacting with materials,so the cleaning process is a comprehensive effect of photothermal and photochemical,which can not only reduce the adverse effects of photothermal effect on the surface,but also achieve high quality and high efficiency surface cleaning.According to the bonding characteristics of the surface attachment and the substrate of the offshore instrument,the conditions for removing the attachment by UV laser were obtained,which provided a theoretical basis for the modeling of UV laser cleaning.Based on the principle of interaction between laser and substance,a comprehensive photochemical and photothermal model of uv laser cleaning surface attachment was established by using Fourier heat transfer equation,Beer Lambert law and Boltzmann distribution,and energy conservation equation.The plasma shielding effect,thermal vibration effect,UV laser cleaning mechanism and cleaning threshold are considered in this model.The comparative experimental study of UV laser and infrared laser cleaning attachment was carried out,and the surface temperature,surface morphology and element content were characterized after infrared and ultraviolet laser cleaning at the same power,which indirectly verified the UV laser cleaning mechanism and laid a foundation for subsequent simulation research.The photochemical and photothermal models were established to simulate the uv laser cleaning process.Finite element method was used to solve the model,and the temperature field and stress field distribution of the surface after uv laser cleaning were obtained.The influence of laser energy density on temperature field and stress field distribution at different positions is analyzed.Through the photochemical analysis and calculation of uv laser interaction with materials,the expression of the ratio of UV laser photochemical interaction and photothermal interaction under different laser energy density is obtained.According to the photochemical and photothermal properties of UV laser,an experimental device for cleaning the surface attachments of offshore instruments by UV laser is developed.Three different attachments on the surface of offshore instruments were tested with this device.Through the experiments,the components of three different attachments were determined,and the corresponding cleaning thresholds were calculated,and the influence rules of laser cleaning process parameters(laser energy density,scanning speed and scanning times)on cleaning quality were obtained.The dynamic process and physical phenomena of ultraviolet laser cleaning were observed by using a high-speed camera.It was found that smoke was formed and accompanied by plasma in the laser action area.The comparative experimental study of UV laser and infrared laser cleaning different attachments was carried out.It is found that the surface is relatively smooth and flat after UV laser cleaning,and there is no obvious residue on the surface of the substrate.The surface quality of offshore instruments was studied by UV laser cleaning.By analyzing the surface morphology,composition,surface roughness and microhardness of different attachments after laser cleaning,the reasonable process parameters of UV laser cleaning offshore instruments were obtained.The wettability and corrosion resistance of the surface cleaned by UV laser were studied.The results show that the surface cleaned by UV laser has good corrosion resistance,and the surface cleaned by laser energy density can obtain good hydrophobicity after surface modification.This study provides a theoretical basis for the application of laser cleaning technology to surface decontamination and antifouling of offshore instruments.