Application Research On Laser Cleaning Of Epoxy-Paint From Ship Plates

Laser cleaning technology has prominent advantages in removing paint on the surface of ship plate compared with traditional technology,such as non-contact processing,less damage to the substrate,wide range of cleaning materials,less environmental pollution,etc.Laser cleaning technology can remove paint quickly and effectively with extremely small damage to the substrate.It has received extensive attention in the related process exploration and theoretical research in recent ten years.The research focus is on the use of laser cleaning technology to remove the epoxy anti-rust coating on the surface of the 921A steel substrate.The basic characteristics of the epoxy paint and 921A steel were introduced.The nanosecond pulse laser with 1064 nm wavelength was determined as equipment used in the research based on the results of absorbance experiments.The range of energy density was determined by combining the experimental results of cleaning threshold and ablation threshold.The experimental schemes of laser de-painting such as laser parameter array were developed.The experiments removing epoxy coating from ship plates were conducted.And the macro and micro characterization and detection were carried out.The effects of different laser cleaning parameters on the paint removal effect and the damage of substrate were analyzed.Laser paint stripping parameters with high cleaning efficiency,high cleaning rate and little damage to the substrates were initially determined.Furthermore,the effects of laser cleaning with different parameters on the mechanical properties,corrosion properties and coating properties of 921A steel sheets were studied based on above results.Meanwhile,with the comparison of the traditional hand-polished samples,the process parameters of laser cleaning were further optimized.The results show that there is no obvious change in tensile strength of the samples when the laser energy density is in the range of 13J/cm~2~18J/cm~2.Their micro-hardness is obviously higher than that of the samples without cleaning.And the hardness decreases gradually with the depth of laser cleaning while the laser energy density increases gradually.The results also show that the surface roughness of the samples is increasing after cleaning,which cause the decreases of its adhesion to the paint.Compared with manual polishing samples,the surface corrosion resistance performance of the samples after cleaning is better with higher energy density of laser.The optimized process parameters of laser cleaning on ship plates were obtained,which including power 100w,pulse width 100ns,lap rate 50%,energy density13.8J/cm~2,and defocus amount-2mm~+2mm.The parameters can meet the four requirements of high cleaning efficiency,high cleaning degree,no damage to the substrate and good coating effect at the same time.