Effect Of Laser Cleaning Research Articles

Effect of High-Power Laser Cleaning for Surface Contaminants Removal on SS304L

In this study, artificially formed corrosion and paint layers on 304L stainless steel (SS304L) specimen were removed using a kilowatt level high-power Nd:YAG laser. A laser power of 1140 W and a pulse duration of 89 ns were used for the corrosion removal, and a laser power of 850 W and a pulse duration of 54 ns were adopted for the paint removal. Surface composition was analyzed via electron probe micro-analysis (EPMA) and x-ray diffraction (XRD) analysis before and after the laser cleaning process, confirming that the corrosion and paint layers were successfully removed from the SS304L surface by the laser cleaning process. The effect of the laser cleaning process on the mechanical properties of SS304L was investigated. The hardness and tensile strength of the laser-cleaned specimens were analyzed to determine their mechanical properties. After the laser cleaning process, the surface hardness was slightly increased up to depths of 250 µm for the corrosion removal and up to 50 µm for the paint removal. However, only marginal changes in tensile strength and elongation were detected after the laser cleaning process. These results confirmed that laser cleaning can effectively remove surface contaminants (i.e., corrosion and paint) on SS304L with only a minimum modification of microstructure and mechanical properties.

Wavelet Packet Transform and Deep Learning-based Fusion of Audio-Visual Signals: A Novel Approach for Enhancing Laser Cleaning Effect Evaluation

Wavelet Packet Transform and Deep Learning-based Fusion of Audio-Visual Signals: A Novel Approach for Enhancing Laser Cleaning Effect Evaluation

Effects of laser cleaning on the condition of different silk model samples using varying wavelengths and pulse durations

The cleaning of aged silk fibers poses a common challenge in the conservation of textiles, since traditional cleaning techniques often yield unsatisfactory results or even harm objects. In this regard, cleaning objects with laser radiation is a promising addition to the range of available methods. Due to it being contactless, even brittle and touch-sensitive objects with disfiguring or harmful soiling could potentially be cleaned and therefore made accessible for research and presentation. Examples of treatment have sometimes shown spectacular results. Still there is some skepticism concerning the safety of this treatment for textile materials, which has been strengthened through previous 532 nm wavelength nanosecond laser cleaning studies on silk fibers. Taking these published results into account, the range of examined laser parameters has been extended in this study, from 532 nm nanosecond laser to 1064 nm nanosecond and even 800 nm femtosecond laser, reevaluating the effect of this treatment on the fibers. The physicochemical processes taking place on the silk fibers when cleaning with lasers are complex and still not fully understood. The aim of this project was therefore to bring more clarification about potential effects of those processes on the condition of silk samples treated with a set of different parameters for wavelength, pulse duration, energy density and number of pulses per spot. It also looks at the influence of the presence of soiling on the results. The analysis of potential effects was then carried out using statistical methods and advanced analytics. Scanning electron microscopy, Fourier-transform infrared spectroscopy and colorimetry technology provided the required insights to better assess the effects. Results show that laser cleaning of silk fibers, like most other conventional cleaning techniques, is not completely without risk, but knowing what the possible effects are helps making decisions on whether the benefits of the technique used justify these risks.

Experimental study on hydrophobic properties and corrosivity of laser cleaned 7075 aluminum alloy anodized film surface

In this paper, nanosecond pulse laser was used to clean the anodic oxide film on the 7075 aluminum alloy surface. The effects of different laser energy densities (3.11–4.44 J/cm2) on the 7075 aluminum alloy surface morphology, composition, roughness, microhardness and contact angle were studied. The hydrophobicity of aluminum alloy surface after laser cleaning was studied, and the effect of laser cleaning on the corrosion resistance of aluminum alloy surface was analyzed. The results show that when the laser energy density reaches 4.44 J/cm2, the surface oxygen content of 7075 aluminum alloy is 0.37 % and the surface roughness is 0.395 μm. Laser cleaning can remove the anodic oxide film on the surface of 7075 aluminum alloy. The new surface formed after laser cleaning is acceptable without damage. Compared with mechanical removal method, under the specific laser energy density (4.44 J/cm2), the microhardness of the surface is slightly improved, while the hydrophobicity is significantly improved, which provides the feasibility of anti-corrosion for regular use after laser cleaning. This work provides basic research and practical guidance for laser cleaning of anodic oxide film on 7075 aluminum alloy surface.

Effect of laser cleaning on adhesive properties of carbon fiber composite materials

A pulsed fiber laser was used to conduct laser cleaning experiments on the composite paint layer on the surface of carbon fiber composite materials (carbon fiber-reinforced plastic (CFRP)). The influence of laser energy density and laser travel speed on the cleaning effect was studied. The surface morphology, surface roughness and phase composition of the cleaned sample were analyzed. After bonding, tensile testing was conducted on the bonding part to verify the impact of laser cleaning on the bonding performance. The research results indicate that the cleaning effect gradually improves with the increase of laser energy density or the decrease of travel speed. In this experiment, when the laser energy density is 4.00[Formula: see text]J/cm2 and the travel speed is 6.5[Formula: see text]mm/s, the phase composition of the cleaned substrate surface is only C, without TiO2 and BaSO4. This indicates that the paint layer has been completely removed under this process parameter. By selecting reasonable process parameters, the surface paint layer of CFRP can be effectively removed, and a good surface morphology can be obtained without damage to the carbon fiber. Meanwhile, the mechanical properties after bonding can be improved.

Laser waterless cleaning of residual organic solvents on the surface of polyurethane coatings.

Residual organic solvents have a great impact on the physical and mental health of equipment operators in industry and agriculture. Laser waterless cleaning technology of residual organic solvents on the surface of polyurethane coatings has great application prospects and is a good way to tackle the pollution problem. In this paper, the evolutionary behavior of a laser waterless cleaning mechanism and substrate surface state is analyzed. The influence law of laser energy density and scanning speed on the residual solvent cleaning effect was investigated. The optimal laser cleaning parameters were obtained by comprehensive evaluation of the substrate surface cleaning effect and microscopic morphology. The peak of solvent characteristics before and after laser cleaning was detected by Raman spectroscopy. The results demonstrated that the laser cleaning effect was better with the increase of energy density or the decrease of scanning speed in the substrate damage range, and the best laser cleaning parameters were laser energy density of 0.24J/c m 2 and scanning speed of 500mm/s. A significant reduction of the peak of Raman spectroscopy was found, reflecting the excellent effect of laser waterless cleaning of residual organic solvents.

Pulsed laser cleaning of C contamination on a glass insulator surface.

When a pulsed laser cleans a glass insulator, the laser power, scanning speed, and repetition frequency affect the laser-cleaning effect. Herein, we considered glass insulators and their surface contaminations as objects, established a finite element model, analyzed the influence of these parameters on the temperature and stress fields, and explored the optimal cleaning parameters for glass insulator surface contamination. In addition, a laser test platform was constructed to verify the cleaning effect. The results indicated that the difference in the cleaning effect was negligible for lasers at repetition frequencies of 10-75kHz. When the power increased, the scanning speed decreased and the temperature of the fouled layer increased. When the power was 60-70W and the scanning speed was 240mm/s, the equivalent tensile stress did not exceed the tensile strength of the insulator. The ablation reaction can remove the fouling part, and the tensile stress can overcome the adhesion force generated between the dirt and glass insulator to achieve effective cleaning. Experiments confirmed that the surface dirt removal rate of glass insulators can be approximately 99% at 60-70W (laser power) and 240mm/s (scanning speed).

Analysis of Laser Cleaning and Rust Removal Technology for Substation Isolator Switches

After running for a long time, isolator switches are prone to be covered with dirt and corrosion. Switch cleaning is necessary for good operation and safety. Laser cleaning technology for rust removal is emerging in recent years. This paper introduces the technical principles of laser cleaning for rust removal in detail, designs a specific process scheme and takes a steel plate sample cleaning and rust removal as a case. The application effect of laser cleaning and rust removal technology is tested and shows that the technology analyzed in this paper can play a great cleaning effect without damaging the equipment base.

Evaluation of laser cleaning effect for the removal of paint on aluminum alloys

Evaluation of laser cleaning effect for the removal of paint on aluminum alloys

Effect of Laser Cleaning Parameters on Surface Filth Removal of Porcelain Insulator

To study the influence of the laser power, scanning speed, and cleaning water content on the laser cleaning effect and obtain the best cleaning parameters, this paper conducted a simulation analysis of the laser cleaning process and carried out a pulse laser cleaning of porcelain insulators experiment to verify. The results show that the cleaning rate gradually increases as the laser power increases from 20 W to 25 W. As the scanning speed increases from 1000 mm/s to 2500 mm/s, the laser overlapping rate gradually decreases, and the cleaning takes the lead in increasing and then decreasing. The appropriate cleaning water content is conducive to laser cleaning; when the water content is 0.115 g, the cleaning efficiency reaches the highest value of 98.20%. When the laser power is 25 W, and the scanning speed is 2000 mm/s, the cleaning efficiency can reach the highest value of 96.87%. This paper shows that the reasonable choice of cleaning parameters can effectively clean the insulator surface filth and obtain a better surface morphology.

Welding Defect and Mechanical Properties of Nanosecond Laser Cleaning 6005A Aluminum Alloy.

Nanosecond laser cleaning effectively removes oxide film and dirt from the surface of aluminum body parts for rail transit, as well as improving surface properties. The effect of laser cleaning on the quality of weld was studied in detail for different scanning frequencies and cleaning speeds. The effect of post-weld laser cleaning on weld quality was investigated. After laser cleaning at different parameters, the surface oxygen content was decreased and the surface roughness and surface hardness were increased. Variation of surface oxygen content was related to energy density and spot density. The lowest oxygen content was obtained at 150 W, 100 Hz and 0.8 m/min. Laser-generated craters changed surface morphology and improved surface roughness. The mechanical properties of the welded joints were slightly improved, which relates to a decrease in porosity. The minimum porosity of the laser-cleaned weld was 0.021%. This work provides new ideas for the nanosecond laser cleaning of aluminum alloy and its welding properties.

Investigating the potential of the Nd:YAG and Er:YAG lasers for the cleaning of feathers: a pilot study

A dual-wavelength Q-switched Nd:YAG laser emitting at 1064 nm and 532 nm and an Er:YAG laser were tested on a range of feathers containing melanin, carotenoids and psittacofulvins. Dyed, white and iridescent feathers, as well as down feathers, were also included in the study. First, the damage threshold fluence was determined for each type of feather and then, as appropriate, laser tests were conducted on feathers artificially soiled with dust or carbon black. The Nd:YAG laser was unsuccessful at cleaning feathers soiled with carbon black. Better outcomes were obtained on feathers soiled with dust: the Nd:YAG laser was effective at both wavelengths at removing dust from white feathers, dyed feathers and yellow feathers containing psittacofulvins. Feathers containing melanin, as their main colourant, were found to have a much lower damage threshold fluence than other feathers. Also, laser radiation at 532 nm at high fluences can cause discolouration on pink feathers containing carotenoids. Finally, it was not possible to remove dust from down feathers without causing thermal damage. This investigation showed that laser cleaning using a Q-switched Nd:YAG laser can remove dust from certain types of feathers. However, further research is needed to assess any potential chemical or long-term effects of laser cleaning on feathers. Finally, the Er:YAG laser was found to be unsuitable for laser cleaning resulting in thermal damage to all feathers at low fluences.

Nanosecond pulsed laser cleaning of titanium alloy oxide films: Modeling and experiments

Nanosecond pulsed laser cleaning is an indispensable green technology. A three-dimensional (3-D) finite element model (FEM) was used to predict the surface temperature during laser cleaning. Then, the macroscopic morphology of the FEM that was obtained was verified using digital ultra-depth-of-field microscopy (OM). Finally, the variation in the surface morphology with the maximum power density (F), x-axis spot overlap ratio (Ux), and y-axis spot overlap ratio (Uy) was determined using field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). The change in surface composition was analysed using X-ray photoelectron spectroscopy (XPS), and optical emission spectroscopy (OES) was used to monitor laser cleaning. Transmission electron microscopy (TEM) was used to analyse the surface secondary oxidation thickness. The original surface consisted of titanium oxides (Ti4+ and Ti3+) and organics. The Ti0 peak was enhanced, and the O content was reduced after laser cleaning. Therefore, the laser-cleaning effect was clear. The surface was smooth without cracks when the maximum power density and the spot overlap ratio were set to 31.85 MW/cm2 and 80 %, respectively. A dense and uniformity oxide film, 29 nm thickness, was formed on the surface of TA15 titanium alloy after laser cleaning. Changes in F, Ux, and Uy caused noticeable changes in the Ti I and Ti II peaks in the OES spectra, which were used to monitor laser cleaning.

Laser Cleaning Surface Roughness Estimation Using Enhanced GLCM Feature and IPSO-SVR

In order to evaluate the effect of laser cleaning, a new method of workpiece surface roughness estimation is proposed. First, a Cartesian robot and visible-light camera are used to collect a large number of surface images of a workpiece after laser cleaning. Second, various features including the Tamura coarseness, Alexnet abstract depth, single blind/referenceless image spatial quality evaluator (BRISQUE), and enhanced gray level co-occurrence matrix (EGLCM) are computed from the images above. Third, the improved particle swarm optimization (IPSO) is used to improve the training parameters of support vector regression (SVR). The learning factor of SVR adopts the strategy of dynamic nonlinear asynchronous adaptive adjustment to improve its optimization-processing ability. Finally, both the image features and the IPSO-SVR are considered for the surface roughness estimation. Extensive experiment results show that the accuracy of the IPSO-SVR surface roughness estimation model can reach 92.0%.

Finite element simulation of temperature field in laser cleaning of TA15 titanium alloy oxide film

<p indent=0mm>Laser cleaning is a noncontact cleaning method that uses a short-pulse high power density laser to irradiate an object. The pollutants are removed by the complex physical and chemical interactions between the laser and the object to be cleaned. The mechanism of laser cleaning is very complex, including photodegradation, photodetachment, and photovibration, which are closely related to the temperature distribution in the laser-cleaning process. In this study, the finite element simulation model of laser cleaning of TA15 titanium alloy oxide film is established by using Comsol Multiphysics commercial simulation software. The influence of spot shape, laser energy, loading mode, and pulse width on the titanium alloy oxide film temperature field is analyzed. The results showed that the substrate was severely damaged by a millisecond pulse laser. The shorter the pulse width, the smaller the surface thermal diffusion. The square flat-top spot was more evenly heated than the Gaussian spot, and the rectangular pulse was less damaged than the Gaussian spot. The laser-cleaning effect of titanium alloy oxide film was the best when the square flat-top laser was loaded in a rectangular pulse.

Effect of Laser Cleaning and Hyperpassivation on the Electrochemical Behavior of AA2024-T3

Environmentally sustainable surface pretreatments and coating systems are needed in the aerospace industry. Laser cleaning is one such surface pretreatment method that reduces the need of hazardous chemicals, and their associated monitoring and disposal, for cleaning metal parts. Research was conducted to investigate how two laser surface pretreatments, (i) cleaning and (ii) hyperpassivation, affect the electrochemical behavior of aluminum alloy 2024-T3. The difference between the two pretreatments was the laser fluence per pulse, 5.2 (cleaning) vs 10.8 J cm−2 (hyperpassivation), respectively. Comparison studies were performed using specimens pretreated by standard wet chemical cleaning and deoxidation. The laser pretreated and solution processed specimens were characterized using electrochemical methods, digital optical microscopy, optical profilometry, scanning electron microscopy, and depth profiling X-ray photoelectron spectroscopy. The laser cleaning and hyperpassivation pretreatments both clean the surface and improve the corrosion resistance of this alloy in naturally aerated 0.5 M Na2SO4, as compared to the solution processed specimen. This is evidenced by suppressed anodic and cathodic polarization curve currents, increased polarization resistance, and increased low frequency impedance modulus values. The improved corrosion resistance results from the formation of a thicker and presumably less defective oxide layer on the aluminum and reduced exposure of Cu-rich second-phase particles.

Effect of laser cleaning on mechanical properties of laser lap welded joint of SUS310S stainless steel and 6061 aluminum alloy

Laser cleaning was successfully applied to laser lap welding of SUS310S stainless steel and 6061 aluminum alloy. The length and width of the fish scale pit tended to increase and decrease with increasing the scanning speed from 3000 mm/s to 7000 mm/s after laser cleaning. While, the depth of the fish scale pit was higher at the scanning speed of 5000 mm/s than the other. In the welded joint, except for metallurgical bonding, a relatively strong mechanical bonding occurred in the interface for the specimens cleaned at the scanning speeds of 3000 mm/s and 5000 mm/s during laser cleaning. The fish scale pit on the cleaned surface of stainless steel could improve the spread out of the melting aluminum alloy, causing the appearance of the relatively strong mechanical bonding. The maximum tensile shear force achieved 1948 N and increased 54% compared to the one without laser cleaning. The application of laser cleaning with the suitable parameters can effectively enhance the mechanical properties of the laser lap welded joints.

Effect of laser cleaning of carbon fiber-reinforced polymer and surface modification on chemical activity and bonding strength

Bonding has been used to repair carbon fiber-reinforced polymer (CFRP) materials. However, research has shown that resin residue on the surface of CFRP can cause adhesion problems. Therefore, a reliable surface cleaning procedure is necessary to remove the resin residue before bonding. In this paper, the surface resin was removed by laser cleaning, while the surface properties of CFRP were improved. A pulsed laser cleaning experiment was designed to study the chemical activity and bonding strength of CFRP treated by laser with different laser power and scanning speed. The results showed that as the contact angle of the material surface decreased, chemical activity and adhesive properties were improved. The surface pretreated with laser power of 16 W (scanning speed of 1500 mm/s) had no resin residue and the best adhesive properties; the bonding strength was 1.6 times higher than that of the untreated surface, and the failure mode was dominated by a cohesive damage mode.

Investigation on the peak temperature and surface defects on the carbon steel treated by rotating CW laser

A newly developed rotating continuous-wave laser equipment was adopted as an alternative laser-based surface cleaning method. To evaluate the thermal effects of laser cleaning on base material, a modified calculation method for laser-induced peak temperature distribution considering overlapping effects was proposed. Various laser-processing parameters were adopted to irradiate carbon steel plates. The re-melted zone (MZ) of laser-treated specimens was observed under optical microscopy and used to verify the calculation method. Surface morphologies and roughness of laser-treated specimens were also investigated. The results showed that the peak temperature distribution obtained from the modified calculation method properly describes the MZ depth in laser-treated specimens. Investigation on laser-treated specimens revealed that results of laser heat effects improved in rougher surface conditions, and that frequent overlapping of laser beam can induce surface defects. The modified calculation method could help to optimize laser processing parameters to reduce melting of base material and avoid surface defects.

Effect of laser power on cleaning mechanism and surface properties.

In this paper, the mechanism of laser dry cleaning was introduced, and the influence of different power on laser cleaning effect and surface performance after cleaning were investigated. The cleaning effect of 60-120 W cleaning power on the oxidized layer of a Q235 surface was analyzed by experiment and simulation. The results showed that the cleaning power of 70 W makes the surface performance after cleaning of the samples relatively optimized. The best cleaning power is 90 W. The sample surface of 100 W is the smoothest, but it causes slight damage to the matrix. The cleaning power of 120 W has the maximum friction coefficient, but it has the maximum damage to the matrix.