scholarly journals Nanosecond Laser Fabrication of Hydrophobic Stainless Steel Surfaces: The Impact on Microstructure and Corrosion Resistance

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1577 ◽  
Author(s):  
Mehran Rafieazad ◽  
Jaffer Jaffer ◽  
Cong Cui ◽  
Xili Duan ◽  
Ali Nasiri
Keyword(s):  
Stainless Steel ◽  
Base Metal ◽  
Melting Process ◽  
Contact Angles ◽  
Laser Surface Texturing ◽  
Nanosecond Laser ◽  
Textured Surfaces ◽  
Laser Texturing ◽  
Steel Surfaces ◽  
The Impact

Creation of hydrophobic and superhydrophobic surfaces has attracted broad attention as a promising solution for protection of metal surfaces from corrosive environments. This work investigates the capability of nanosecond fiber laser surface texturing followed by a low energy coating in the fabrication of hydrophobic 17-4 PH stainless steel surfaces as an alternative to the ultrashort lasers previously utilized for hydrophobic surfaces production. Laser texturing of the surface followed by applying the hydrophobic coating resulted in steady-state contact angles of up to 145°, while the non-textured coated base metal exhibited the contact angle of 121°. The microstructure and compositional analysis results confirmed that the laser texturing process neither affects the microstructure of the base metal nor causes elemental loss from the melted regions during the ultrafast melting process. However, the electrochemical measurements demonstrated that the water-repelling property of the surface did not contribute to the anticorrosion capability of the substrate. The resultant higher corrosion current density, lower corrosion potential, and higher corrosion rate of the laser textured surfaces were ascribed to the size of fabricated surface micro-grooves, which cannot retain the entrapped air inside the hierarchical structure when fully immersed in a corrosive medium, thus degrading the material’s corrosion performance.

scholarly journals Long-Term Influence of Laser-Processing Parameters on (Super)hydrophobicity Development and Stability of Stainless-Steel Surfaces

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2240 ◽  
Author(s):  
Peter Gregorčič ◽  
Marjetka Conradi ◽  
Luka Hribar ◽  
Matej Hočevar
Keyword(s):  
Contact Angle ◽  
Stainless Steel ◽  
Processing Parameters ◽  
Nanosecond Laser ◽  
Stainless Steel Surface ◽  
Textured Surfaces ◽  
Laser Texturing ◽  
Important Challenge ◽  
Faster Development

Controlling the surface wettability represents an important challenge in the field of surface functionalization. Here, the wettability of a stainless-steel surface is modified by 30-ns pulses of a Nd:YAG marking laser (λ = 1064 nm) with peak fluences within the range 3.3–25.1 J cm−2. The short- (40 days), intermediate- (100 days) and long-term (1 year) superhydrophilic-to-(super)hydrophobic transition of the laser-textured surfaces exposed to the atmospheric air is examined by evaluating its wettability in the context of the following parameters: (i) pulse fluence; (ii) scan line separation; (iii) focal position and (iv) wetting period due to contact angle measurements. The results show that using solely a short-term evaluation can lead to wrong conclusions and that the faster development of the hydrophobicity immediately after laser texturing usually leads to lower final contact angle and vice versa, the slower this transition is, the more superhydrophobic the surface is expected to become (possibly even with self-cleaning ability). Depending on laser fluence, the laser-textured surfaces can develop stable or unstable hydrophobicity. Stable hydrophobicity is achieved, if the threshold fluence of 12 J cm−2 is exceeded. We show that by nanosecond-laser texturing a lotus-leaf-like surface with a contact angle above 150° and roll-off angle below 5° can be achieved.

Fabrication and Wettability Analysis of Hydrophobic Stainless Steel Surfaces With Microscale Structures From Nanosecond Laser Machining

2018 ◽  
Vol 6 (3) ◽  
Author(s):  
Cong Cui ◽  
Xili Duan ◽  
Brandon Collier ◽  
Kristin M. Poduska
Keyword(s):  
Stainless Steel ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Surface Structures ◽  
Laser Machining ◽  
Nanosecond Laser ◽  
Static Contact ◽  
Submicron Structures ◽  
Steel Surfaces ◽  
Hierarchical Multiscale

In this work, nanosecond laser machining is used to fabricate hydrophobic 17-4 PH stainless steel surfaces with microscale and submicron structures. Four surface structures were designed, with microscale channels and pillars (100 μm pitch size) of uniform heights (100 μm) or alternating heights (between 100 μm and 50 μm). During fabrication, the high-power laser beams also created submicron features on top of the microscale ones, leading to hierarchical, multiscale surface structures. Detailed wettability analysis was conducted on the fabricated samples. Measured static contact angles of water on these surfaces are over 130 deg without any coating, compared to ∼70 deg on the original steel surface before laser machining. Slightly lower contact angle hysteresis was also observed on the laser machined surfaces. Overall, these results agree with a simple Cassie–Baxter model for wetting that assumes only fractional surface area contact between the droplet and the surface. This work demonstrates that steel surfaces machined with relatively inexpensive nanosecond laser can achieve excellent hydrophobicity even with simple microstructural designs.

Nanoengineered Superhydrophobic Surfaces to Prevent Adhesion of Listeria monocytogenes for Improved Food Safety

2020 ◽  
Vol 63 (5) ◽  
pp. 1401-1407
Author(s):  
Bog Eum Lee ◽  
Youngsang You ◽  
Won Choi ◽  
Eun-mi Hong ◽  
Marisa M. Wall ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Biofilm Formation ◽  
Electrochemical Etching ◽  
Contact Angles ◽  
Bacterial Attachment ◽  
Superhydrophobic Surfaces ◽  
List Type ◽  
Ptfe Film ◽  
Steel Surfaces

HighlightsNanoporous superhydrophobic surfaces were fabricated using electrochemical etching and Teflon coating.Adhesion of Listeria monocytogenes to the nanoengineered stainless steel surfaces was reduced.Self-cleanable food-contact surfaces prevent bacterial attachment and subsequent biofilm formation.Abstract. Bacterial attachment on solid surfaces and subsequent biofilm formation is a significant problem in the food industry. Superhydrophobic surfaces have potential to prevent bacterial adhesion by minimizing the contact area between bacterial cells and the surface. In this study, stainless steel-based superhydrophobic surfaces were fabricated by manipulating nanostructures with electrochemical etching and polytetrafluoroethylene (PTFE) film. The formation of nanostructures on stainless steel surfaces was characterized by field emission scanning electron microscopy (FESEM). The stainless steel surfaces etched at 10 V for 5 min and at 10 V for 10 min with PTFE deposition resulted in average water contact angles of 154° ±4° with pore diameters of 50 nm. In addition, adhesion of Listeria monocytogenes was decreased by up to 99% compared to the bare substrate. These findings demonstrate the potential for the development of antibacterial surfaces by combining nanoporous patterns with PTFE films. Keywords: Electrochemical etching, PTFE, Nanoengineered surface, L. monocytogenes, Superhydrophobic.

Splat Solidification of Tin Droplets

1996 ◽  
Author(s):  
R. Bhola ◽  
S. Chandra
Keyword(s):  
Experimental Study ◽  
Stainless Steel ◽  
Simple Model ◽  
Surface Temperature ◽  
Steel Surface ◽  
Liquid Droplet ◽  
Contact Angles ◽  
Stainless Steel Surface ◽  
Splat Solidification ◽  
The Impact

Abstract An experimental study was done of the impact and solidification of tin droplets falling on a stainless steel surface. The surface temperature was varied from 25°C to 240°C. Measurements were made of droplet diameters and contact angles during droplet spread. At a surface temperature of 240°C there was no solidification, and a simple model of liquid droplet impact successfully predicted the extent of droplet spread. Droplets impacting on surfaces at 25°C and 150°C solidified before spreading was complete.

The Impact of Acid Treatments and Electropolishing Stainless-Steel Surfaces on Tritium Inventories

2017 ◽  
Vol 71 (3) ◽  
pp. 275-280 ◽  
Author(s):  
C. Fagan ◽  
M. Sharpe ◽  
W. T. Shmayda ◽  
W. U. Schröder
Keyword(s):  
Stainless Steel ◽  
Steel Surfaces ◽  
The Impact ◽  
Acid Treatments

scholarly journals Efficacy of Neutral Electrolyzed Water for Inactivation of Human Norovirus

2017 ◽  
Vol 83 (16) ◽  
Author(s):  
Eric Moorman ◽  
Naim Montazeri ◽  
Lee-Ann Jaykus
Keyword(s):  
Stainless Steel ◽  
Receptor Binding ◽  
Electrochemical Activation ◽  
Viral Gastroenteritis ◽  
Human Norovirus ◽  
Electrolyzed Water ◽  
Astm Method ◽  
Steel Surfaces ◽  
Soil Load ◽  
The Impact

ABSTRACT Human norovirus (NoV) is the leading cause of acute gastroenteritis worldwide. Persistence on surfaces and resistance to many conventional disinfectants contribute to widespread transmission of norovirus. We examined the efficacy of neutral electrolyzed water (NEW; pH 7) for inactivation of human NoV GII.4 Sydney in suspension (ASTM method 1052-11) and on stainless steel surfaces (ASTM method 1053-11) with and without an additional soil load. The impact of the disinfectant on viral capsid was assessed using reverse transcriptase quantitative PCR (RT-qPCR; with an RNase pretreatment), SDS-PAGE, transmission electron microscopy, and a histo-blood group antigen (HBGA) receptor-binding assay. These studies were done in parallel with those using Tulane virus (TuV), a cultivable human NoV surrogate. Neutral electrolyzed water at 250 ppm free available chlorine produced a 4.8- and 0.4-log10 reduction in NoV genome copy number after 1 min in suspension and on stainless steel, respectively. Increasing the contact time on surfaces to 5, 10, 15, and 30 min reduced human NoV genomic copies by 0.5, 1.6, 2.4, and 5.0 log10 and TuV infectious titers by 2.4, 3.0, 3.8, and 4.1 log10 PFU, respectively. Increased soil load effectively eliminated antiviral efficacy regardless of testing method and virus. Exposure to NEW induced a near complete loss of receptor binding (5 ppm, 30 s), degradation of VP1 major capsid protein (250 ppm, 5 min), and increased virus particle aggregation (150 ppm, 30 min). Neutral electrolyzed water at 250 ppm shows promise as an antinoroviral disinfectant when used on precleaned stainless steel surfaces. IMPORTANCE Norovirus is the leading cause of acute viral gastroenteritis worldwide. Transmission occurs by fecal-oral or vomitus-oral routes. The persistence of norovirus on contaminated environmental surfaces exacerbates its spread, as does its resistance to many conventional disinfectants. The purpose of this research was to evaluate the antinoroviral efficacy of neutral electrolyzed water (NEW), a novel chlorine-based disinfectant that can be used at reduced concentrations, making it more environmentally friendly and less corrosive than bleach. An industrial-scale electrochemical activation device capable of producing relatively stable electrolyzed water at a wide pH range was used in this study. Experiments showed that 250 ppm NEW effectively eliminated (defined as a 5-log10 reduction) human norovirus GII.4 Sydney (epidemic strain) on clean stainless steel surfaces after a 30-min exposure. Supporting studies showed that, like bleach, NEW causes inactivation by disrupting the virus capsid. This product shows promise as a bleach alternative with antinoroviral efficacy.

scholarly journals Laser Surface Texturing and Characterization of Austenitic Stainless Steel for the Improvement of Its Surface Properties

2021 ◽  
Author(s):  
Yassmin Seid Ahmed ◽  
Jose Mario Paiva ◽  
Fred L. Amorim ◽  
Ricardo D. Torres ◽  
Wagner de Rossi ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Surface Texturing ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Textured Surfaces ◽  
Aisi 304 ◽  
Steel Aisi

Abstract A detailed investigation of laser textured surfaces produced on austenitic stainless steel (AISI 304) was carried out. Three different textures were produced by a Ti sapphire laser. The processed surfaces were characterized by surface morphology, phase structure, micro-hardness, surface roughness, and wettability. A ball-on-disk tribometer was used to study the tribological performance of both untextured and textured samples. The experimental observations demonstrate that laser surface texturing (LST) improves both surface wettability and surface roughness. Average surface roughness (Ra) was increased by 350% and the contact angle was reduced from 43° to 22°. The textured surfaces show a lower coefficient of friction and better wear resistance than the untextured surface. Out of the investigated patterns, the square textures exhibited a maximum reduction of 68% in the friction coefficient and a 50% lower wear rate.

Study of the wettability behavior of stainless steel surfaces after ultrafast laser texturing

2018 ◽  
Vol 352 ◽  
pp. 370-377 ◽  
Author(s):  
C. Sciancalepore ◽  
L. Gemini ◽  
L. Romoli ◽  
F. Bondioli
Keyword(s):  
Stainless Steel ◽  
Ultrafast Laser ◽  
Laser Texturing ◽  
Steel Surfaces
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