scholarly journals Corrosion Behavior of Laser Interference Structured Al 2024 Coated with a Chromate-containing Epoxy Primer

CORROSION ◽  
10.5006/3717 ◽  
2021 ◽  
Author(s):  
Jiheon Jun ◽  
Adrian Sabau ◽  
Michael Stephens
Keyword(s):  
Corrosion Behavior ◽  
Laser Fluence ◽  
Salt Spray ◽  
Corrosion Damage ◽  
Nanosecond Laser ◽  
Type I ◽  
Preparation Technique ◽  
Laser Interference ◽  
Chemical Cleaning ◽  
Epoxy Primer

In this study, corrosion behavior of laser-interference treated Al20204-T3 specimens, which were coated with a primer, is presented. The surface of as-received Al2024-T3 specimens were laser-interference structured by splitting the primary beam of a Q-switched Nd:YAG pulsed nanosecond laser into two beams and focusing them to the same spot on the specimen surface. After being stored in plastic cases for up to 70 days, without any additional cleaning, the specimens were spray painted with a chromate-containing epoxy primer, CA7233, compliant to MIL-PRF-23377 Type I Class C2 specification. The corrosion behavior of laser-interference specimens was assessed against that of specimens prepared by chromated conversion coating and sulfuric acid anodizing treatments. After the ASTM B117 corrosion exposure, it was found that the laser processed specimens exhibited only few blisters. On one hand, most specimens prepared at a laser fluence of 1.78 J/cm2, without any additional chemical cleaning, were found to develop one very small blister after only 96 h of exposure. However, the growth of these blisters was not significant even after 1000 h of salt spray exposure. On the other hand, only a fraction of the specimens prepared at a laser fluence of 1.24 J/cm2 and acetone wiped right after the laser structuring, were found to develop several tiny blisters after 790 h and longer exposure. Overall, it was found that the corrosion damage was minimized at a laser rastering speed of 4 mm/s, condition for which only 33% of specimens developed very minor corrosion damage. The ASTM D1654 creepage ratings, which was used to evaluate the corrosion damage along the scribe lines, were found to be at least nine for all coated panels. These results indicate that the laser-interference technique with the additional acetone wiping has the potential to be further developed as a non-chemical surface preparation technique for chromate-containing epoxy primers coating systems.

scholarly journals Effect of Oxide Scale Microstructure on Atmospheric Corrosion Behavior of Hot Rolled Steel Strip

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 517
Author(s):  
Bin Sun ◽  
Lei Cheng ◽  
Chong-Yang Du ◽  
Jing-Ke Zhang ◽  
Yong-Quan He ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Oxide Scale ◽  
Corrosion Product ◽  
Corrosion Behavior ◽  
Corrosion Test ◽  
Atmospheric Corrosion ◽  
Corrosion Mechanism ◽  
Type I ◽  
Rust Layer ◽  
Hot Rolled

The atmospheric corrosion behavior of a hot-rolled strip with four types (I–IV) of oxide scale was investigated using the accelerated wet–dry cycle corrosion test. Corrosion resistance and porosity of oxide scale were studied by potentiometric polarization measurements. Characterization of samples after 80 cycles of the wet–dry corrosion test showed that scale comprised wüstite and magnetite had strongest corrosion resistance. Oxide scale composed of inner magnetite/iron (>70%) and an outer magnetite layer had the weakest corrosion resistance. The corrosion kinetics (weight gain) of each type of oxide scale followed an initial linear and then parabolic (at middle to late corrosion) relationship. This could be predicted by a simple kinetic model which showed good agreement with the experimental results. Analysis of the potentiometric polarization curves, obtained from oxide coated steel electrodes, revealed that the type I oxide scale had the highest porosity, and the corrosion mechanism resulted from the joint effects of electrochemical behavior and the porosity of the oxide scale. In the initial stage of corrosion, the corrosion product nucleated and an outer rust layer formed. As the thickness of outer rust layer increased, the corrosion product developed on the scale defects. An inner rust layer then formed in the localized pits as crack growth of the scale. This attacked the scale and expanded into the substrate during the later stage of corrosion. At this stage, the protective effect of the oxide scale was lost.

scholarly journals Direct Laser Interference Patterning of Diffraction Gratings in Safrofilcon-A Hydrogel: Fabrication and Hydration Assessment

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 679
Author(s):  
Daniel Sola ◽  
Stephan Milles ◽  
Andrés F. Lasagni
Keyword(s):  
Laser Fluence ◽  
Contact Lenses ◽  
Laser Source ◽  
Spatial Period ◽  
Laser Interference ◽  
Periodic Patterns ◽  
Hydration Properties ◽  
Water Contact ◽  
Direct Laser ◽  
Direct Laser Interference Patterning

Refractive index modification by laser micro-structuration of diffractive optical devices in ophthalmic polymers has recently been applied for refractive correction in the fields of optics and ophthalmology. In this work, Safrofilcon-A hydrogel, used as soft contact lenses, was processed by direct laser interference patterning (DLIP) to fabricate linear periodic patterns on the surface of the samples. Periodic modulation of the surface was attained under two-beam interference by using a Q-switched laser source with emission at 263 nm and 4 ns pulse duration. Features of processed areas were studied as a function of both the interference spatial period and the laser fluence. Optical confocal microscopy used to evaluate the topography of the processed samples showed that both structured height and surface roughness increased with laser fluence. Static water contact angle (WCA) measurements were carried out with deionized water droplets on the structured areas to evaluate the hydration properties of DLIP structures. It was observed that the laser structured areas induced a delay in the hydration process. Finally, microstructural changes induced in the structured areas were assessed by confocal micro-Raman spectroscopy showing that at low laser fluences the polymer structure remained almost unaltered. In addition, Raman spectra of hydrated samples recovered the original shape of areas structured at low laser fluence.

Electrochemical and Salt Spray Corrosion Behavior of Copper Alloy Contact Wires in Chloride Solution

2014 ◽  
Vol 789 ◽  
pp. 622-626
Author(s):  
Peng Chao Zhang ◽  
Jian Zhang ◽  
Jin Chuan Jie ◽  
Yuan Gao ◽  
Yong Dong ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Corrosion Test ◽  
Chloride Solution ◽  
Copper Alloys ◽  
Salt Spray ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Corrosion Mechanism ◽  
Salt Spray Corrosion ◽  
Surface Morphologies

The effect of different alloying elements on corrosion behavior of copper alloys was investigated using electrochemical corrosion and salt spray corrosion test in NaCl solution. Cu-Ag has the most stable corrosion current in the potentiostatic scanning test, exhibiting a better corrosion resistant performance. It can be analyzed from corrosion surface morphologies that Cu-Ag presents exfoliation corrosion mechanism while Cu-Sn shows crevice corrosion mechanism. Cu-Mg has a complex corrosion process caused by multiple corrosion mechanism. In the salt spray corrosion test, the corrosion degree of Cu-Ag is lighter than those of Cu-Sn and Cu-Mg after 24h test. Therefore, the Cu-Ag alloy exhibits the best corrosion resistance in chloride solution.

LMFBR Steam Generator Materials Development at Westinghouse

1983 ◽  
Vol 105 (4) ◽  
pp. 719-725 ◽  
Author(s):  
M. A. Hebbar ◽  
C. E. Sessions
Keyword(s):  
Water Chemistry ◽  
Corrosion Behavior ◽  
Tube Model ◽  
Expansion Joint ◽  
Chemical Cleaning ◽  
Materials Development ◽  
The Past ◽  
Component Design ◽  
The Impact ◽  
Double Wall

The impact of Materials and Processes (M and P) development activities at the Nuclear Components Division - Breeder Reactor Components Project of Westinghouse are described. Nine specific M and P programs have been performed over the past five years and the conclusions drawn from each are summarized herein. These engineering activities could be classified as component design, fabrication, and testing results. However, the discussion presented is from a materials engineer’s viewpoint as to how the previously proposed development tasks have answered existing questions about either design, manufacturing, or plant operation. The nine areas which are discussed include (i) double-wall tubing, (ii) tube-to-tubesheet welding, (iii) few tube model fabrication and testing, (iv) tube support plates, (v) shell welding, (vi) convoluted shell expansion joint, (vii) water chemistry and corrosion behavior, (viii) chemical cleaning, and (ix) surface contamination protection.

scholarly journals Phase analysis and corrosion behavior of brazing Cu/Al dissimilar metal joint with BAl88Si filler metal

2021 ◽  
Vol 10 (1) ◽  
pp. 1318-1328
Author(s):  
Hua Yu ◽  
Liangliang Zhang ◽  
Shuai Li ◽  
Fangfang Cai ◽  
Yunpeng Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Corrosion Behavior ◽  
Salt Spray ◽  
Ternary Eutectic ◽  
Average Particle Size ◽  
Testing Machine ◽  
Joint Interface ◽  
Average Particle ◽  
Automatic Production ◽  
Brazed Joint

Abstract To meet the requirements of automatic production, a new type of green BAl88Si cored solder was developed. The lap brazing experiments were carried out with copper and aluminum as brazing substrates. The microstructure, phase composition, and corrosion behavior of solder joint interface were studied by field emission scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, electron backscattering diffraction, tensile testing machine, and electrochemical workstation. The results show that the brazing joint of Cu/BAl88Si/Al is metallurgical bonding, and the brazing joint of Cu/BAl88Si/Al is composed of Cu9Al4, CuAl2, a-Al, (CuAl2 + a-Al + Si) ternary eutectic. In addition, there is no obvious preference for each grain in the brazing joint, and there are S texture {123}<634>, Copper texture {112}<111>, and Brass texture {110}<112>. The interface of Cu9Al4/CuAl2 is a non-coherent crystal plane and does not have good lattice matching. The average particle size of CuAl2 is 11.95 µm and that of Al is 28.3 µm. However, the kernel average misorientation (KAM) value at the brazed joint interface is obviously higher than that at the brazed joint interface copper, so the defect density at the brazed joint interface aluminum is higher than that at the brazed joint interface copper. At the same time, due to poor corrosion resistance at the interface on the aluminum side of the brazed joint, serious corrosion spots and corrosion cracks occur at the same time, which leads to the shear performance of the brazed joint decreasing by about 75% after salt spray test for 240 h.

High-power laser interference lithography process on photoresist: Effect of laser fluence and polarisation

2009 ◽  
Vol 255 (10) ◽  
pp. 5537-5541 ◽  
Author(s):  
M. Ellman ◽  
A. Rodríguez ◽  
N. Pérez ◽  
M. Echeverria ◽  
Y.K. Verevkin ◽  
...  
Keyword(s):  
High Power ◽  
Laser Fluence ◽  
Interference Lithography ◽  
Laser Interference Lithography ◽  
High Power Laser ◽  
Laser Interference ◽  
Power Laser ◽  
Lithography Process

A New Double Laser Recrystallization Technique to Induce Ultra-Large Poly-Si Grains

2001 ◽  
Vol 685 ◽  
Author(s):  
Minghong Lee ◽  
Seungjae Moon ◽  
Mutsuko Hatano ◽  
Costas P. Grigoropoulos
Keyword(s):  
Grain Growth ◽  
Excimer Laser ◽  
Laser Fluence ◽  
Laser Power ◽  
Laser Flash ◽  
Process Window ◽  
Nanosecond Laser ◽  
Solidification Velocity ◽  
Laser Recrystallization ◽  
Nucleation Sites

AbstractA new double laser recrystallization technique that can produce lateral grains of tens of micrometers is presented. A nanosecond laser (excimer or Nd:YLF laser) and a pulse modulated Ar+ laser are used in the experiment. The effect of different parameters on lateral grain growth is investigated. These parameters include the time delay between the two lasers, the excimer laser fluence, the Ar+ laser power and the pulse duration. This process has wide process window and is insensitive to both the excimer laser fluence and the Ar+ laser power fluctuations. Preheating and melting of the a-Si film with the Ar+ laser before firing the excimer laser is found to be necessary for inducting lateral grain growth. The transient excimer laser irradiation is believed to generate nucleation sites for initiating the subsequent lateral grain growth. The solidification dynamics of the process is probed by high spatial and temporal resolution laser flash photography. A lateral solidification velocity of about 10 m/s is observed.

Fabrication of periodic microscale stripes of silver by laser interference induced forward transfer and their SERS properties

2021 ◽  
Author(s):  
Huijuan Shen ◽  
Yaode Wang ◽  
Liang Cao ◽  
Ying Xie ◽  
Lu Wang ◽  
...  
Keyword(s):  
Film Thickness ◽  
Laser Fluence ◽  
Nano Particles ◽  
Good Resolution ◽  
Laser Interference ◽  
Ag Nps ◽  
Wide Range ◽  
Forward Transfer ◽  
Stripe Structure ◽  
Average Size

Abstract The micro-stripe structure was prepared by laser interference induced forward transfer (LIIFT) technique, composed of Ag nano-particles (NPs). The effects of the film thickness with the carbon nano-particles mixed polyimide (CNPs@PI), Ag film thickness, and laser fluence were studied on the transferred micro-stripe structure. The periodic Ag micro-stripe with good resolution was obtained in a wide range of CNPs@PI film thickness from ~ 0.5 μm to ~ 1.0 μm for the Ag thin film ~ 20 nm. The distribution of the Ag NPs composing the micro-stripe was compact. Nevertheless, the average size of the transferred Ag NPs was increased from ~ 41 nm to ~ 197 nm with the change of the Ag donor film from ~ 10 nm to ~ 40 nm. With the increase of the laser fluence from 102 mJ•cm-2 to 306 mJ•cm-2 per-beam, the transferred Ag NPs became aggregative, improving the resolution of the corresponding micro-stripe. Finally, the transferred Ag micro-stripe exhibited the significant surface enhanced Raman scattering (SERS) property for rhodamine B (RhB). While the concentration of the RhB reached 10-10 mol•L-1, the Raman characteristic peaks of the RhB were still observed clearly at 622 cm-1, 1359 cm-1, and 1649 cm-1. These results indicate that the transferred Ag micro-stripe has potential application as a SERS chip in drug and food detection.

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