scholarly journals Effect of Defocused Nanosecond Laser Paint Removal on Mild Steel Substrate in Ambient Atmosphere

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5969
Author(s):  
Zhong Zheng ◽  
Chaofan Wang ◽  
Gang Huang ◽  
Wenju Feng ◽  
Dun Liu
Keyword(s):  
Surface Roughness ◽  
Thermal Stress ◽  
Ambient Air ◽  
Inert Atmosphere ◽  
Compressed Air ◽  
Nanosecond Laser ◽  
Ambient Atmosphere ◽  
Stress Effect ◽  
Removal Technology ◽  
Paint Removal

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.

scholarly journals Investigation of Multiparameter Laser Stripping of AlTiN and DLC C Coatings

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 951
Author(s):  
Tomáš Primus ◽  
Josef Hlavinka ◽  
Pavel Zeman ◽  
Jan Brajer ◽  
Martin Šorm ◽  
...  
Keyword(s):  
Surface Roughness ◽  
High Efficiency ◽  
Steel Substrate ◽  
Cutting Tools ◽  
High Hardness ◽  
Working Time ◽  
Nanosecond Laser ◽  
Altin Coating ◽  
Successful Removal ◽  
Frequency Laser

The lifetime and properties of cutting tools and forming moulds can be prolonged and enhanced by the deposition of hard, thin coatings. After a certain period of usage, the coating will deteriorate. Any remaining coating must be removed prior to successful recoating. Laser stripping is a fast and environmentally friendly coating removal method. In this paper, we present laser removal of two types of coatings deposited on a 1.2379 tool steel substrate, namely, an AlTiN coating with high hardness and a DLC C coating with a small coefficient of friction (COF). A powerful nanosecond laser was employed to remove the coating from the substrate with high efficiency, along with suitable residual surface roughness. Measurements were taken of surface roughness, removed depth, and working time on a stripped area of 1 cm2. The samples were evaluated under a microscope, with a 3D profilometer, and by EDS chemical analysis. Successful removal of the coating was confirmed by optical analysis, but detailed chemical characterisation showed that about 30% of the coating element may remain on the surface. Moreover, a working time of less than 7.5 s per cm2 was obtained in this study. In addition, it was shown that the application of a second low energy, high frequency laser beam pass leads to remelting of the peaks of the material and reduced surface roughness.

Simulation of nanosecond laser cleaning the paint based on the thermal stress

Optik ◽  
2021 ◽  
Vol 227 ◽  
pp. 165589
Author(s):  
Yao Lu ◽  
LiJun Yang ◽  
MaoLu Wang ◽  
Yang Wang
Keyword(s):  
Thermal Stress ◽  
Laser Cleaning ◽  
Nanosecond Laser

scholarly journals Determination of Glycol Ethers in Ambient Air by Adsorption Sampling and Thermal Desorption with GC/MS Analysis: Performance Evaluation and Field Application

2012 ◽  
Vol 9 (2) ◽  
pp. 970-979
Author(s):  
Young-Kyo Seo ◽  
Sung-Ok Baek
Keyword(s):  
Thermal Desorption ◽  
Analytical Method ◽  
Ambient Air ◽  
Industrial Area ◽  
Field Application ◽  
Ambient Atmosphere ◽  
Glycol Ethers ◽  
Ms Analysis ◽  
Sampling Campaign

Some of glycol ethers, such as 2-methoxyethanol (2-ME) and 2-ethoxyethanol (2-EE) are known to be toxic and classified as hazardous air pollutants in USA, Japan and Germany. In Korea, however, there has been no study conducted so far for these compounds in ambient air. In addition, no clear methodologies for the measurement of glycol ethers have been yet established. We carried out this study to evaluate a sampling and analytical method for the determination of glycol ethers, in ambient air samples collected in specific industrial areas of South Korea. To measure glycol ethers, adsorption sampling and thermal desorption with GC/MS analysis were used in this study. The analytical method showed good repeatability, linearity and sensitivity. The lower detection limits were estimated to be approximately 0.3∼0.5 ppb. Based on storage tests, it was suggested that samples should be analyzed within two weeks. It was also demonstrated that this method can be used for the simultaneous measurement of glycol ethers and other aromatic VOCs such as benzene, toluene, and xylenes. Field sampling campaign was carried out at 2 sites, located in a large industrial area, from October 2006 to June 2007, and a total of 480 samples were collected seasonally. Among them, 2-ME was not detected from any samples, while 2-EE and 2-Ethyloxyethylacetate (2-EEA) were found in 7 and 70 samples, respectively. The measured concentrations of 2-EE and 2-EEA for samples were ranged from 0.7-2.5 ppb and from 0.5-10.5 ppb, respectively. To our knowledge, this is the first measurement report for glycol ethers in the ambient atmosphere not only in Korea but also the rest of the world.

Prediction of Surface Roughness in Compressed Air Jet Assisted High Speed End Milling of Silicon Using Diamond Coated Tools

2012 ◽  
Vol 576 ◽  
pp. 41-45
Author(s):  
A.K.M. Nurul Amin ◽  
M.A. Mahmud ◽  
M.D. Arif
Keyword(s):  
Mathematical Model ◽  
Surface Roughness ◽  
Surface Finish ◽  
High Speed ◽  
End Milling ◽  
Silicon Wafers ◽  
Compressed Air ◽  
Machining Parameters ◽  
High Quality ◽  
Ductile Mode

The majority of semiconductor devices are made up of silicon wafers. Manufacturing of high-quality silicon wafers includes numerous machining processes, including end milling. In order to end mill silicon to a nano-meteric surface finish, it is crucial to determine the effect of machining parameters, which influence the machining transition from brittle to ductile mode. Thus, this paper presents a novel experimental technique to study the effects of machining parameters in high speed end milling of silicon. The application of compressed air, in order to blow away the chips formed, is also investigated. The machining parameters’ ranges which facilitate the transition from brittle to ductile mode cutting as well as enable the attainment of high quality surface finish and integrity are identified. Mathematical model of the response parameter, the average surface roughness (Ra) is subsequently developed using RSM in terms of the machining parameters. The model was determined, by Analysis of Variance (ANOVA), to have a confidence level of 95%. The experimental results show that the developed mathematical model can effectively describe the performance indicators within the controlled limits of the factors that are being considered.

scholarly journals Thermal Stress Effect on Density Changes of Hemp Hurds Composites

2016 ◽  
Vol 11 (2) ◽  
pp. 67-76
Author(s):  
Ivana Schwarzova ◽  
Julia Cigasova ◽  
Nadezda Stevulova
Keyword(s):  
Thermal Decomposition ◽  
Thermal Stress ◽  
Composite System ◽  
Gradual Increase ◽  
Bound Water ◽  
Stress Effect ◽  
Original Sample ◽  
Density Reduction ◽  
Filling Agent ◽  
Naoh Solution

Abstract The aim of this article is to study the behavior of prepared biocomposites based on hemp hurds as a filling agent in composite system. In addition to the filler and water, an alternative binder, called MgO-cement was used. For this objective were prepared three types of samples; samples based on untreated hemp hurds as a referential material and samples based on chemically (with NaOH solution) and physically (by ultrasonic procedure) treated hemp hurds. The thermal stress effect on bulk density changes of hemp hurds composites was monitored. Gradual increase in temperature led to composites density reduction of 30-40 %. This process is connected with mass loss of the adsorbed moisture and physically bound water and also with degradation of organic compounds present in hemp hurds aggregates such as pectin, hemicelluloses and cellulose. Therefore the changes in the chemical composition of treated hemp hurds in comparison to original sample and its thermal decomposition were also studied.

scholarly journals Evaluating the measurement interference of wet rotating-denuder–ion chromatography in measuring atmospheric HONO in a highly polluted area

2019 ◽  
Vol 12 (12) ◽  
pp. 6737-6748 ◽  
Author(s):  
Zheng Xu ◽  
Yuliang Liu ◽  
Wei Nie ◽  
Peng Sun ◽  
Xuguang Chi ◽  
...  
Keyword(s):  
Ion Chromatography ◽  
Atmospheric Chemistry ◽  
Eastern China ◽  
Ambient Air ◽  
Absorption Efficiency ◽  
Water Soluble ◽  
East China ◽  
Oh Radicals ◽  
Ambient Atmosphere ◽  
High Concentrations

Abstract. Due to the important contribution of nitrous acid (HONO) to OH radicals in the atmosphere, various technologies have been developed to measure HONO. Among them, wet-denuder–ion-chromatography (WD/IC) is a widely used measurement method. Here, we found interferences with HONO measurements by WD/IC based on a comparison study of concurrent observations of HONO concentrations using a WD/IC instrument (Monitor for AeRosols and Gases in ambient Air, MARGA) and long-path absorption photometer (LOPAP) at the Station for Observing Regional Processes of the Earth System (SORPES) in eastern China. The measurement deviation of the HONO concentration with the MARGA instrument, as a typical instrument for WD/IC, is affected by two factors. One is the change in denuder pH influenced by acidic and alkaline gases in the ambient atmosphere, which can affect the absorption efficiency of HONO by the wet denuder to underestimate the HONO concentration by up to 200 % at the lowest pH. The other is the reaction of NO2 oxidizing SO2 to form HONO in the denuder solution to overestimate the HONO concentration, which can be increased by to 400 % in denuder solutions with the highest pH values due to ambient NH3. These processes are in particularly important in polluted east China, which suffers from high concentrations of SO2, NH3, and NO2. The overestimation induced by the reaction of NO2 and SO2 is expected to be of growing importance with the potentially increased denuder pH due to the decrease in SO2. We further established a method to correct the HONO data measured by a WD/IC instrument such as the MARGA. In case a large amount WD/IC-technique-based instruments are deployed with the main target of monitoring the water-soluble composition of PM2.5, our study can help to obtain a long-term multi-sites database of HONO to assess the role of HONO in atmospheric chemistry and air pollution in east China.

Rotary Ultrasonic Machining of Basalt Rock Using Compressed Air As Coolant: A Study on Edge Chipping and Surface Roughness

2019 ◽  
Author(s):  
Palamandadige Fernando ◽  
Meng Zhang ◽  
Zhijian Pei ◽  
Adam Owens
Keyword(s):  
Surface Roughness ◽  
Cutting Force ◽  
Construction Material ◽  
Compressed Air ◽  
Ultrasonic Power ◽  
Ultrasonic Machining ◽  
Rotary Ultrasonic Machining ◽  
Machining Processes ◽  
Edge Chipping ◽  
Basalt Rock

Abstract The aim of this study is to investigate the edge chipping and surface roughness of basalt rock processed by rotary ultrasonic machining (RUM) using compressed air as coolant. Basalt rock is commonly used as a building and construction material for foundations and dams, as well as in architectural designs such as constructing thin veneers and facades. Rotary ultrasonic machining, a hybrid process of grinding and ultrasonic machining, is employed to drill difficult-to-machine materials such as ceramics, composites, titanium alloys, stainless steel, etc. RUM has many advantages over conventional machining processes such as twist drilling. These advantages include lower cutting force, higher surface quality, lower tool wear, etc. This paper is the first in literature to report a study on edge chipping and surface roughness on RUM of basalt rock using cold compressed air as coolant. The effects of three input variables (tool rotation speed, feedrate, and ultrasonic power) on cutting force, torque, edge chipping, and surface roughness were studied. Experimental results obtained from this investigation show that RUM with cold air as the coolant has the capability to machine holes in basalt rock with a surface roughness of less than 3.5 μm without severe edge chipping.

Vortex Tube Impact on Cooling Milling Machining

2012 ◽  
Author(s):  
Basel Alsayyed ◽  
Mohammad O. Hamdan ◽  
Saud Aldajah
Keyword(s):  
Surface Roughness ◽  
Surface Finish ◽  
Vortex Tube ◽  
Compressed Air ◽  
Heat Map ◽  
Milling Operations ◽  
Three Samples ◽  
Cutting Operation ◽  
Water Base ◽  
Vortex Tubes

In this paper, the authors will present the use of a vortex tube in cooling milling operations. The focuses will be regarding the surface finish and temperature of the tool during the cutting operation. Three cooling setups, cutting without coolant, cooling with a water base traditional coolant, and cooling with vortex tube will be compared. A Flir E320 UV camera has been used to capture the heat map around the tool during the cutting process. The surface roughness has been measured and analysed for all three samples using Taylor/Hobson Precision Surtronc 3+ apparatus. The findings of this study have shown comparative efficient cooling using the vortex tubes. The vortex tube cooling is also cleaner and can be directed in such a way to collect the chips as they develop with the least mess or no mess. Vortex tubes have no moving parts, and it is very much maintenance free device. Compressed air is needed to feed the vortex tube, which is available usually in any machine shop.

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