paint removal
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2022 ◽  
Vol 34 (1) ◽  
pp. 012002
Author(s):  
Runpeng Miao ◽  
Tao Wang ◽  
Tao Yao ◽  
Shaowu Hu ◽  
Xudong Huang ◽  
...  

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5969
Author(s):  
Zhong Zheng ◽  
Chaofan Wang ◽  
Gang Huang ◽  
Wenju Feng ◽  
Dun Liu

The obvious advantages of laser paint removal technology make it a viable alternative to traditional paint removal methods. Infrared nanosecond laser was used to remove paint from car body. The microstructure, composition, surface roughness, hardness and ablative products of the samples were analyzed. The effect of the process combination of laser defocus distance and ambient atmosphere (ambient air, compressed air and inert atmosphere) on the substrate damage and the paint removal effectiveness was explored, and the related mechanism was discussed. Defocus not only changed the fluence of laser spot but also increased the spot diameter. The effect of defocused laser paint removal on the paint and substrate was caused by the superposition of these two factors. The results show that the laser with defocus distance of +4 mm effectively removed the paint in inert atmosphere and has the least adverse effect on the substrate. The content of C element and organic components on the substrate surface was the lowest, and its surface roughness and hardness was very close to the uncoated substrate. Focused laser paint removal in ambient air caused the most serious damage to the substrate. Its surface microhardness increased by 11 HV, and the influence depth reached 37 µm. The mechanism of laser paint removal without auxiliary gas is the superposition of laser plasma effect, laser gasification effect and thermal stress effect. In open atmosphere (compressed air and inert atmosphere), the mechanism of laser paint removal is laser gasification effect and thermal stress effect. This research can provide practical references and theoretical basis for the large-scale industrial application of low/non-damage laser paint removal technology.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Wenfeng Yang ◽  
Ziran Qian ◽  
Yu Cao ◽  
YongChao Wei ◽  
Chanyuan Fu ◽  
...  

Reliability and controllability of selective removal of multiple paint layers from the surface of aircraft skin depend on effective online monitoring technology. An analysis was performed on the multi-pulse laser-induced breakdown spectroscopy (LIBS) on the surface of the aluminum alloy substrate, primer, and topcoat. Based on that, an exploration was conducted on the changes of the characteristic peaks corresponding to the characteristic elements that are contained in the topcoat, primer, and substrate with different layers of a laser action, in combination with analysis of microscopic morphology, composition, and depth of laser multi-pulse pits. The results show that the appearance and increase of the characteristic peak intensity of the Ca I at the wavelength of 422.7 nm can be regarded as the basis for the complete removal of the topcoat; the decrease or disappearance of the characteristic peak intensity can be regarded as the basis for the complete removal of the primer. Al I spectrum at the wavelength of 394.5 nm and 396.2 nm can be adopted to characterize the degree of damage to the aluminum alloy substrate. The feasibility and accuracy of the LIBS technology for the laser selective paint removal process and effect monitoring of aircraft skin were verified. Demonstrating that under the premise of not damaging the substrate, laser-based layered controlled paint removal (LLCPR) from aircraft skin can be achieved by monitoring the spectrum and composition change law of specified wavelength position corresponding tothe characteristic elements that are contained in the specific paint layer.


Rare Metals ◽  
2021 ◽  
Author(s):  
Qi Sun ◽  
Jian-Zhong Zhou ◽  
Xian-Kai Meng ◽  
Jia-Nian Yang ◽  
Zhao-Heng Guo ◽  
...  

2021 ◽  
Vol 14 (3) ◽  
pp. 34-37
Author(s):  
Edwin Büchter
Keyword(s):  

2021 ◽  
Vol 42 (5) ◽  
pp. 598-608
Author(s):  
Bingyuan Han ◽  
Yawei Xu ◽  
Kebing Zhou ◽  
Weining Lei ◽  
Xiaoping Li ◽  
...  

2021 ◽  
Author(s):  
G. Haider ◽  
M. Othayq ◽  
S. A. Shirazi

Abstract Sand production is a significant challenge in petroleum engineering, and specifically in multiphase gas condensate wells where small amount of liquid is present with the gas. Sand particles entrained in multiphase flow can severely affect the integrity of fluid transportation structures such as pipelines, elbows, and reducers. Traditionally, sand management techniques such as sand screens and gravel packs are used to control sand. However, small particles can pass through these controls. Furthermore, small particles can block a part of the sand screen, causing high velocities in other sections which can cause erosion of the sand screen openings allowing larger particles to pass through which in turn cause more erosion. Furthermore, these small particles are highly susceptible to turbulent regions of flow and can cause severe erosion in these regions. Hence, it is critically important to understand the erosion caused by small particles. This study investigates the effect of small particles on erosion. Small particle erosion is more severe in gas dominated multiphase flows such as annular and mist flows than liquid dominated bubbly and slug flows. A 90-degree standard elbow is used in the experimental and numerical analyses because of its high erosion vulnerability and its importance in pipeline applications. This is because the flow changes direction in this geometry which has complex implications on erosion. This study follows the below mentioned research method: 1) Flow Visualization Study: To understand the flow behavior in bend. 2) Paint-Removal Study: To visualize the progress of paint-removal pattern and to identify the erosion hot spots caused by sand particles. 3) Multiphase Erosion Experiments: To determine the wall thickness loss on identified hot spots using fix-mounted temperature compensated ultrasonic measurement technique. 4) Computational Fluid Dynamics (CFD) Study: To compare erosion patterns with CFD simulations of multiphase flow. Furthermore, the effects of particle size on erosion ratio and its distribution in pipe bends are discussed. The CFD results of larger particles agree better with experimental data than for smaller particles using existing erosion models.


2021 ◽  
Author(s):  
Mazen Othayq ◽  
Ghulam Haider ◽  
Ronald E. Vieira ◽  
Siamack A. Shirazi

Abstract Erosion is a complex process, especially with the presence of small particles and in complex geometries such as elbows in series. Erosion due to the solid particle is affected by different parameters such as material properties, particle material, shape and size, superficial gas and liquid velocities, flow regime and geometry. The main objective of this work is to investigate the effect of particle size in two 3-inch (76.2 mm) diameter elbows in series with curvature radius to pipe diameter ratio (r/D) equal to 1.5. A test section was constructed in a flow loop with a distance between the elbows equal to 12D. Paint removal experiments were conducted to determine the erosion patterns and hot spots of erosion using acrylic elbows. Additionally, erosion experiments were conducted with 300, 75, and 25 μm particle sizes in gas-liquid-sand annular flow in stainless steel elbows. The wall thickness loss of the elbows has been measured using state of the art non-destructive fix-mounted, temperature compensated, ultrasonic transducers. Experimental results showed that higher erosion was obtained with 300 μm particle size where the erosion in the second elbow is lower than the first elbow with the 12D distance. With respect to the maximum erosion ratio of the second elbow to the first elbow, the results showed that the ratio of erosion rates in two elbows (second to first) decreases with increasing the particle size. A higher ratio of the two elbows was obtained with 25 μm compared to 300 and 75 μm particle sizes. However, in the first elbow, the erosion rates decrease with decreasing particle sizes.


Author(s):  
Lyubomir Lazov ◽  
Nikolay Angelov ◽  
Edmunds Teirumnieks ◽  
Imants Adijāns ◽  
Antons Pacejs ◽  
...  

A comparison is made between the laser and sandblasting methods for removing paint from industrial facilities. The advantages of laser ablation are discussed. The possibilities of laser paint removal systems - stationary and moving - are shown. The main factors influencing the laser ablation process and the indicators that determine the quality of the obtained surface are systematized. Researchers' publications on this technological process are analyzed.


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