Surface Preparation Research Articles

Preliminary Results and a Treatment Algorithm for Osteomyelitis of the Distal Tibia and Talus

Category: Hindfoot; Ankle Introduction/Purpose: Management of hindfoot osteomyelitis involves eradication of infection, deformity correction, and bony stabilization in the setting of bone loss and poor bone quality. This case series of 20 patients presents a two-stage technique: debridement, deformity correction, joint surface preparation, intramedullary reaming with antibiotic-impregnated polymethyl methacrylate rod and ring external fixation, followed by a second stage of external fixator removal and exchange of antibiotic rod for definitive hindfoot fusion rod. The purpose of the study is to highlight techniques and preliminary results that can improve the success of obtaining stable fixation, remission of infection and ultimately fusion. Techniques highlighted are ring fixator placement, antibiotic rod formulation, intramedullary canal preparation, rod exchange and use of blocking screws to enhance compression and axial loading of the fusion. Methods: Twenty patients were treated with this two-stage protocol. The most common indication was post-traumatic osteomyelitis followed by neuropathic (Charcot) joint. All were treated with an initial debridement of nonviable tissue including osteomyelitic bone. The tibiotalar and talocalcaneal joint surfaces were prepared for fusion at the initial debridement. Provisional stabilization and compression were obtained using a ring external fixator for patients without rotational stability. The polymethyl methacrylate-antibiotic impregnated rod (PMMA with gentamycin and vancomycin) was introduced through the calcaneus, talus, and the intramedullary space of the tibia. The patients were kept in the fixator until the skin was healed and all incisions were dry. At this point, the fixator was removed, and the antibiotic rod was exchanged for the definitive hindfoot fusion rod. Results: Cultures were positive for Staphylococcal or Streptococcal species in 60% of cases, Fingeoldia magna 10%, Cutibacterium Acnes 2%, and Gram-negative organisms in 30%. On average patients spent 80 days in the fixator while wounds were healing, and were receiving systemic antibiotics. One patient died while in the frame. There have been no amputations in the series. Of the patients that have completed the protocol, all have gone on to either bony fusion or stable fibrous union. All are able to walk unaided and 25% used an AFO to control and protect the foot and equalize leg length. Secondary procedures are described. Conclusion: This technique of staged fusion for hindfoot osteomyelitis offers the following advantages. The first stage involves thorough debridement and deformity correction. Oftentimes, there is extensive scarring, and the soft tissue envelope is not conducive to internal fixation. This technique allows the soft tissues to heal before placing the definitive internal fixation. It also allows for graduated compression at the fusion site with the ring fixator. The antibiotic rod not only delivers high concentration of local antibiotics, but it prevents deformity recurrence during the compression phase. The definitive rod provides support of pathologic bone and maintains deformity correction.

Eklemeli İmalat ile Üretilen PLA Parçaların Yapıştırılmasında Yapıştırma Parametrelerinin Mekanik Dayanımına Etkisinin İncelenmesi

Geçmişten günümüze plastik malzemeler şekillendirme kabiliyetleri sayesinde endüstrinin her alanında yoğun olarak kullanılmaktadırlar. Özellikle son 10 yılda eklemeli imalat sektöründe masa tipi 3B yazıcıların yaygınlaşmasıyla termoplastikler en çok kullanılan plastik malzeme çeşidi olmuştur. Bununla beraber bu yöntemle üretilen parçaların montajı da bir o kadar önem kazanmıştır. Plastik malzemeler düşük yüzey enerjisine sahip oldukları için yapışkanlı birleştirme işleminin gerçekleştirilmesinde zorluklar vardır. Bu hususta en önemli işlem parametreleri yapıştırıcı tipi, parça yüzey temizliği ve yapıştırma kalınlığıdır. Bu çalışmada; eklemeli imalat yöntemi ile PLA levhalar üretilmiş ve iki farklı yapıştırıcı (Loctite 9492 ve Terason 9225) ile birleştirilmiştir. Yüzey hazırlığı için 320 ve 600 SiC zımpara kullanılarak mekanik zımparalama yapılmıştır. Üç farklı yapıştırıcı kalınlığı (0,3 0,18 ve 0,1mm) ile PLA-PLA malzeme çiftinden yapıştırma bağlantıları oluşturulmuştur. Bağlantılar çekme testine tabi tutularak mekanik özellikleri incelenmiştir. Sonuçlar, 3B baskıda farklı doluluk oranlarında (%100, %80, %60, %40 ve %20) yapılan baskı sonucunda, doluluk oranının yüksekmesiyle birlikte parça mukavemeti artış göstermiştir. Sonuçlar yapıştırma bağlantı mukavemetinin yapıştırıcı çeşidine bağlı olarak yapıştırma kalınlığının değişiminden ters korelasyonlu olarak etkilendiğini ortaya koymuştur. Yapıştırıcı kalınlığının artması Loctite EA 9492 bağlantılarının mukavemetini arttırırken, Teroson PU 9225 bağlantılarında ise tam tersi etki yaratmaktadır.

Preparation of a Wear-Resistant, Superhydrophobic SiO2/Polymethyl Methacrylate Composite Coating on Aluminum Surface Processed with Nanosecond Laser.

Superhydrophobic coatings are limited by complex preparation processes and poor mechanical durability in practical applications. In this study, a mechanically robust superhydrophobic composite coating was applied to an aluminum surface that underwent processing with a nanosecond laser (referred to as a superhydrophobic aluminum surface). It exhibits a high water contact angle (WCA) of 158.81°, a low sliding angle (SA) of less than 5°, and excellent self-cleaning ability. The wear test shows its durability, and the corrosion test shows its excellent corrosion resistance. This study provides a framework for the preparation of robust superhydrophobic surfaces that may have potential applications in many fields.

Kriterij za objektivno određivanje vrijednosti praga osjetljivosti pri filtriranju signala hrapavosti strojno obrađene površine masivnog drva filtrom utemeljenim na brzoj Fourierovoj transformaciji (FFT)

The article presents the method for an objective determination of threshold value, needed for filtering out the anatomical roughness signal, with filter based on fast Fourier Transform (FFT), from surface roughness profile after machining. The method includes experimental preparation of solid wood surface by cutting in such a way to get a surface that can be considered to represent only anatomical roughness, with no other influence. Experiments were performed on radial cross section of solid oak wood (Quercus robur L.) so that the results could be compared with roughness profiles that were previously obtained in experiments after sawing with circular saw. From these samples and based on frequency analysis of anatomical roughness signals, the threshold value was determined to be 1.6 μm. The average value of Ra parameter of anatomical roughness for specimens of radial cross section of solid oak wood was 2.1 μm with standard deviation of 0.3 μm. The importance of choosing adequate sampling length in threshold determination, based on frequency analysis of anatomical roughness signal, was also established.

(Invited) Growth and Characterization of 200 mm SiC Crystals and Substrates

SiC power device technology has over the past years continued to gain massive interest in automotive and industrial applications. Most devices are today fabricated on 150 mm diameter substrates while the 200 mm diameter substrates are still at early stage in both development and in terms of mass production. In this paper, we report the latest progress on STMicroelectronics 200 mm diameter crystals and substrates. To handle the mechanism behind the crystal growth process you need to control the temperature and pressure in the customized graphite growth chamber. We detail the methods that allow to characterize the quality of the ingot by monitoring the relevant properties both related to the grown crystal and to the produced substrate. We also describe the key parameters to be controlled on the substrate to be sure it is suitable for device making (i.e. mechanical behavior, resistivity, surface roughness, effectiveness of the surface preparation).

High Cleanliness and High Hydrophobic/Hydrophilic Contrast Done by Direct Wafer Bonding for Die-to-Wafer Self-Assembly

We propose an innovative process with a high hydrophilic contrast for die-to-wafer self-assembly bonding. Dies and target wafer bonding surfaces first undergo a photolithography process to define bonding sites with a 15 µm step. An efficient cleaning is then performed for direct bonding surface preparation. A carrier is bonded to the bonding site to temporarily protect it during the hydrophobic treatment. After it, water contact angles of 18° and 110° are measured on bonding sites and on hydrophobic area, respectively. Finally, the self-assembly process compatibility is demonstrated with 8x8 mm² dies achieving alignment accuracy of less than 1 µm and excellent bonding interface quality.

Acoustic Emission Sensor-Assisted Process Monitoring of Air Plasma-Sprayed Titanium Deposition

AbstractAcoustic emission is a sensing technique that offers the potential benefit for its use as an in situ monitoring tool for a wide range of manufacturing processes. This work attempts to highlight the robustness of using acoustic emission (AE) data for in-line process monitoring of the air plasma spray deposition technique. As part of this study, titanium powder was deposited under various conditions of robot speed, powder feed rates and the influence of these changes were investigated in the signature obtained from the AE analysis. The post-processed AE data showed sensitivity to these changes through variation in frequencies, power spectral densities and the cumulative energy that gets transmitted to the substrate during the spraying process. The AE signal sensitivity was found to be so robust that it picked up even the differences in the substrate conditions i.e., a substrate used for coating in an as received form vs a substrate that was grit blasted before spraying showed identifiable differences in the AE signature. An attempt to convert an AE signal to energy and then analyse the spraying process in light of the cumulative energy is an investigation first of its kind in this research, hitherto not seen in the literature. In light of the extensive experimental data gathered from the in-house deposition data, the influence of the release of elastic strain energy based on the particle states and the impact on the substrate has been discussed thoroughly. The interdependency of surface preparation, feed rate and the robotic gun scanning speed has been discussed in detail as well. Through the data presented in this study, we advocate the use of AE analysis to be a vital contributor and a welcome move towards digitalisation of the thermal spray process for in-process monitoring.

Study on Nonfluorinated Preparation and Properties of Superhydrophobic Surface

The preparation of a superhydrophobic surface on metal can improve the self-cleaning, anti-fouling, and anti-bacterial properties of the surface. At present, the superhydrophobicity of the sample surface is mostly obtained by modifying the rough surface with fluorine-containing modifiers, which is unfavorable to the environment. Therefore, developing superhydrophobic surfaces without environmental pollution has become a research hotspot. Based on laser etching technology, the rough surface with a micro-nano dual-scale structure was prepared on aluminum alloy, and then a green and natural saturated fatty acid — myristic acid was used to modify the rough surface. Contact angle measuring instrument, depth of field microscope, scanning electron microscope and Fourier transform infrared spectrometer were used to characterize the wettability, surface morphology, and chemical composition of the modified rough surface (S1). Self-cleaning, anti-contamination, antibacterial, mechanical durability, and thermal stability of the S1 surface were tested experimentally. The wetting of droplets on hydrophobic surface was simulated by using COMSOL Multiphysics software, and a computational model was established to compare different functional structures, so as to understand the influence of parameters on the enhancement of hydrophobic properties of material surface. The results showed that the static contact angle (WCA) of the surface modified by myristic acid reached 152.3[Formula: see text], and the hydrophobic index was −0.808, and the WCA value first increased and then decreased with the change of modification time and concentration. With the increase of myristic acid concentration, the peak value of the contact angle WCA of S1 was negatively correlated with modification time. The self-cleaning rate, anti-stain rate, and antibacterial rate of S1 were 91.4%, 83.6% and 88.4%, respectively, showing excellent self-cleaning, anti-stain, and antibacterial ability. In the mechanical durability test, the S1 surface can resist at least 50 times tape peeling, 30 times steel wool friction and wear, the and 180[Formula: see text]g sand falling impact test still keeps superhydrophobic. In the thermal stability test, the S1 surface remains superhydrophobic after heat treatment at 100–200[Formula: see text]C for 30[Formula: see text]h. In this study, the multifunctional superhydrophobic surface was obtained on aluminum alloy by laser etching technology combined with a green fluorine-free modifier, which provided some meaningful ideas and references for the green preparation of superhydrophobic surfaces and the application and development of superhydrophobic surfaces in biomedical metals.

Review on condensation frosting and defrosting experiments for superhydrophobic surfaces

Frosting is a natural phase change phenomenon which happens frequently in nature and industry and has negative effects on a variety of applications. As a passive anti-frosting strategy, superhydrophobic surfaces have been paid more and more attention. To shed light on the process and space–time characteristics of frosting on superhydrophobic surfaces, the preparation methods of superhydrophobic surfaces were introduced first. Then, the internal mechanisms of anti-frosting for superhydrophobic surfaces were revealed from two perspectives of condensation frosting and defrosting. For the preparation of superhydrophobic surfaces, previous studies have shown that laser etching could obtain ideal surface parameters, but there is still a lack of a preparation scheme with low cost and good reliability. For the condensation frosting on superhydrophobic surfaces, the surface with regular surface morphology could realize the spontaneous wettability transformation of the droplets and maintain the size of the condensed droplets within 10–20 μm. The freezing time of droplets on the surface with a regular micro-nano structure is about 4.42 times longer than that on the surface without a regular micro-nano structure. The condensation stage and droplet freezing stage are the keys to preventing frost on superhydrophobic surfaces. For the defrosting on superhydrophobic surfaces, the photothermal defrosting method using metal nanowires, graphene, and carbon nanotubes has a broad application prospect. The results of this study summarized the achievements, problems, and challenges of the current research, so as to provide a reference for the anti-frosting technology of superhydrophobic surfaces in practical applications.

Fabrication of hierarchical micro-groove structures by vibration assisted end fly cutting

Bionic linear micro-groove structure is a common structure in nature, with special functions such as self-cleaning and structural color. Although fast tool servo assisted diamond turning is believed to be an effective method for machining micro-structures, it suffers from defects such as insufficient dynamic response frequency and tool interference in machining linear micro-groove structure. In the present study, a novel vibration-assisted tool end fly cutting technique is proposed to achieve linear micro-groove structure and the hieratical micro-structure surface by the crossing of micro-grooves. A uniform circular tool path is generated by the tool end fly cutting to perform the principal cutting, while a two-degree-of-freedom servo-vibration platform provides high-frequency, low-amplitude and multi-modal actuation compatible with the principal cutting motion. Then the tool path required for the composite machining of the micro-groove structure surface is planned, and a uniform and consistent micro-groove structure surface can be generated. The machining capability of the system is verified the experimental machining of multi-layer micro-groove structures. This study provides a technology reference for the preparation of micro-groove structure surfaces.

Laser belt processed micropillars with microporous structure and nanoparticles to control the surface wettability of superhydrophobic Inconel 718 alloy

The superhydrophobic surface features such as self-cleaning, keeping dry and low adhesion have wide application prospects in biotechnology, medicine, and engineering. As a superhydrophobic surface machining method, pulsed laser ablation has attracted wide attention due to its high precision. However, due to the efficiency, pulsed laser composite processing technology has gradually developed into the main preparation method for superhydrophobic surfaces. A effective machining method (laser belt collaborative processing) for superhydrophobic surface preparation was proposed in this paper. The microgroove surface could be prepared by using a pyramid abrasive belt with regular consistency of abrasive height and a high precision picosecond laser. After rotating the workpiece 90°, the micropillar surface could be formed by machining again. The height of micropillars increases significantly with the increase of the laser power. There are multiscale structures on the micropillar surface, including micropores, microaggregates, and nanoparticles. With the design spacing of the micropillar increasing to 80 μm, the contact angle reaches a maximum value of 153.8° The adsorption of carbon elements and the low solid-liquid contact fraction are beneficial to the enhancement of surface hydrophobicity. The superhydrophobic micropillar surface is extremely stable, which can withstand various harsh treatments/environments, such as sandpaper abrasion, tape peeling. A new processing method for superhydrophobic micropillar surface preparation was proved, which is conducive to the application of superhydrophobic surfaces.

Cicada Wing-Inspired Transparent Polystyrene Film Integrating Self-Cleaning, Antifogging, and Antibacterial Properties.

A transparent film integrating antifouling, antifogging, and antibacterial properties is crucial for its application as a protective mask, goggles, or lens. Herein, applying dynamic injection molding coupled with a bionic gradient template, a fast and efficient method is proposed for the preparation of the bionic polystyrene surface (BNPPS) with a cicada wing-inspired nanopillar structure. The contact angle of the BNPPS film increases continuously along the wing vein, while the sliding angle decreases continuously, mimicking the gradient wetting state of a cicada wing and providing excellent self-propelled removal properties for tiny water droplets. Notably, the BNPPS film has a transmittance higher than 90% and a reflectivity lower than 5% in the visible light range. Dyeing water, milk, juice, cola, and ink can slide smoothly from the BNPPS film surface without leaving any residue. Importantly, the nanopillars on the BNPPS film surface can penetrate and kill most of the Escherichia coli within 20 min. Therefore, the prepared BNPPS film with sufficient mechanical strength gathers the unique properties of the cicada wing together. The proposed research is expected to offer valuable guidance for fabricating self-cleaning, antifogging, and antibacterial optical devices that could be utilized in medical and vision systems operating in harsh environments.

Point-Contact Bonding of Integrated Three-Dimensional Manifold Microchannel Cooling Within Direct Bonded Copper Platform

Abstract A microchannel heat sink integrated with a three-dimensional manifold using direct bonded copper (DBC) is promising for high power density electronics due to the combination of low thermal resistance and reduced pressure drop. However, this requires much progress on the fabrication and high-quality point-contact bonding processes of the microchannel substrate and three-dimensional manifold DBCs. In this study, we have developed processing techniques for surface preparations and high-quality point-contact solder bonding between the two DBC substrates. We utilized chemical polishing followed by electroless plating to prevent excess solder from blocking the microchannels. We performed a parametric study to investigate the impact of bonding time and surface roughness on the tensile strength of the bonding interface. The bonding strength increased from 1.8 MPa to 2.3 MPa as the bonding time increased from 10 to 30 min while reducing the surface roughness from Rz = 0.21 to 0.05 μm, resulting in increasing the bonding strength from 0.16 MPa to 2.07 MPa. We successfully tested the microcooler up to the inlet pressure of 70 kPa and pressure drop of 30 kPa, which translates to the tensile strength at the bonding point contacts, which remains well below the 2.30 MPa. We achieved the junction-to-coolant thermal resistance of 0.2 cm2 K/W at chip heat flux of 590 W/cm2. Thus, our study provides an important proof-of-concept demonstration toward enabling high power density modules for power conversion applications.

INFLUENCE OF BITUMEN-POLYMER AND ASMOL MASTIC COMPOSITIONS ON QUALITY INDICATORS OF MATERIALS FOR ANTI-CORROSION INSULATION OF OIL AND GAS PIPELINES

Underground pipelines operating experience shows that their operating life and reliability largely depend on effectiveness of metal corrosion protection, both internal and external surfaces. In the latter case, along with electrochemical protection, insulation coatings play an important role. In recent years, there has been a trend to use factory-insulated pipes. Its advantages are obvious: high-quality preparation of pipe surface, strict control over compliance with the technological mode of application. However, in some cases it is impossible to do without field coating: during overhaul, diagnostic works on the linear part and process pipelines of pumping stations. In this case, it is relevant the improvement of insulation materials and field coating technologies.The aim of this work was to study the influence of the component composition of bituminous-polymeric and asmolic mastics on their adhesion to the pipe metal and the operational characteristics of the insulating materials. In doing so, the following tasks were solved:A specially developed gravimetric technique to study the interaction of asmol with the metal surface was used. The cover films formed in this process were studied using an electron microscope at a 1000× magnification.It has been shown that when applying asmol coating, its functional groups enter into chemical interaction with the compounds formed on pipe surface. An indirect confirmation of this is an absolute resistance of the asmol coating to repeated flushing with solvents and water. This peculiarity is not observed in the case of bituminous-polymeric coatings: bituminous-polymeric mastic is completely washed off the surface of steel in a similar treatment.Calculating of the «reduced» cost of 1 km of pipeline re-insulation has revealed a significant advantage of asmol-mastic coating over the bituminous-polymeric one from the economic point of view, since the former not only provides a better adherence to the pipe surface, but also achieves significant savings, since a smaller thickness of the protective coating is required.

Methodology for evaluating the mechanical performances of a bonded assembly through complementary mechanical tests

ABSTRACT Bifunctional polymers have been studied as bonding layers (BL) on aluminum surfaces to promote adhesion of adhesives for structural bonding applications. The BL are located at the interface between the aluminum substrate and the adhesive. The mechanical performances of the BL in a bonded assembly were evaluated via several complementary mechanical tests, before and after ageing cycle: single lap shear, Arcan test, three-point bending test, and micro-scratch. The results of these four mechanical tests were compared with those of a raw reference (without any treatment) and a reference that had undergone standard surface preparation (cleaning and etching), in order to assess the mechanical performances of the surface treatment products (BL), and to value these products on the surface treatment market. In order to follow a methodology for selecting the best surface treatments, the mechanical results were compared with each other, and even correlated for samples with bonding layers (containing phosphorus and carboxylic acid functions). The correlation of the results obtained from the four mechanical tests (single lap shear, Arcan, three-point bending, and micro-scratch tests) therefore makes it possible to validate the methodology for evaluating these surface treatments.

A Methylene Blue-Enhanced Nanostructured Electrochemical Immunosensor for H-FABP Myocardial Injury Biomarker.

A sensitive electrochemical immunosensor for the detection of the heart-type fatty acid binding protein (HFABP), an earlier biomarker for acute myocardial infarction than Troponins, is described. The sensing platform was enhanced with methylene blue (MB) redox coupled to carbon nanotubes (CNT) assembled on a polymer film of polythionine (PTh). For this strategy, monomers of thionine rich in amine groups were electrosynthesized by cyclic voltammetry on the immunosensor's gold surface, forming an electroactive film with excellent electron transfer capacity. Stepwise sensor surface preparation was electrochemically characterized at each step and scanning electronic microscopy was carried out showing all the preparation steps. The assembled sensor platform combines MB and PTh in a synergism, allowing sensitive detection of the H-FABP in a linear response from 3.0 to 25.0 ng∙mL-1 with a limit of detection of 1.47 ng∙mL-1 HFABP that is similar to the clinical level range for diagnostics. H-FABP is a newer powerful biomarker for distinguishing between unstable angina and acute myocardial infarction.

Preparation and performance of superhydrophobic surfaces with low surface energy modified attapulgite

Material modification with low surface energy can offer lower surface free energy on micro- and nano-rough structures, which is necessary for developing superhydrophobic surfaces. Based on experiment and molecular simulation, the composite systems of attapulgite (APT) modified by alkylamine, alkylammonium salt and stearic acid were prepared. Combine surface free energy, electrostatic potential distribution, self-diffusion coefficient, and interfacial formation energy to favor the superhydrophobic composite system, and the interaction between low surface materials and attapulgite was explained. The results demonstrate that the hydrophobicity of APT are clearly modified by alkyl amine, alkyl ammonium salt, and stearic acid, and that when the molecular number of low surface energy monomers increases, the surface free energy of the composites first decreases and then increases. At the ideal concentration, the contact angles of alkyl amine/APT and SA/APT composites are all greater than 150°, and the antifouling performance is excellent. Finally, compounding technology was used to further optimize the superhydrophobic composite system. It was discovered that the hydrophobicity and antifouling properties of the composite system were superior to those of the monomer, and the octadecylamine/SA/APT composite system performed optimally at a contact angle of 167.54°.

Fabrication of Micron-Structured Heatable Graphene Hydrophobic Surfaces for Deicing and Anti-Icing by Laser Direct Writing

As a novel method to prepare graphene, the laser-induced graphene (LIG) technology has numerous outstanding properties and has been widely applied in various fields. Nevertheless, the challenge remains to easily and efficiently prepare multifunctional surfaces of graphene through laser microregulation and fine structure design. Here, we successfully fabricated a micron-structure gully graphene surface with hydrophobicity and electrothermal functionality under atmospheric conditions using a 10.6 μm CO2 laser to directly write on the surface of a polyimide film (PI). The impact of the laser scanning speed on the surface morphology and chemical composition of the product was investigated by analyzing the SEM (scanning electron microscope) observations and Raman spectra, respectively. The mechanical stability of the surface was studied by analyzing the contact angle of water droplets on the surface after mechanical circulation and the delayed icing effect after repeated icing. The deicing and anti-icing performance of the surface were analyzed based on its resistance to surface icing and electric deicing time. According to the experimental results, we first observed a linear negative correlation between the generated structure linewidth and the laser scanning speed. Additionally, we successfully achieved one-step preparation of primitive continuous graphene structures with a superhydrophobic capability (151°). Furthermore, our findings indicate that micron-structured graphene surfaces exhibit excellent mechanical stability, effectively delay icing formation, and demonstrate efficient electric deicing effects. These results demonstrate the potential application of CO2 laser-induced graphene technology in the field of surface preparation for deicing and anti-icing. This work offers a novel one-step approach for the fabrication of micron-structured heatable graphene surfaces with simultaneous superhydrophobicity, deicing, and anti-icing functionalities on polymer substrates.

Determining the Role of Oxygen in Obtaining Long-Term Stable Superhydrophilic Surfaces on Metals Treated with a Femtosecond Laser.

Laser processing is a simple way to obtain hydrophobic or even superhydrophobic properties of metal surfaces. However, preparation of superhydrophilic surfaces by this method, the properties of which do not change under the influence of various factors, remains a difficult task. In this work, we show that with increasing laser power, the degree of oxidation of the treated metal surface also increases. As a result, highly oxidized samples showed highly stable superhydrophilic properties. A Janus membrane fabricated from a stainless steel mesh with asymmetric hydrophilic-hydrophobic wettability demonstrated stable water diode properties. In addition, it was found that during the examination of sample surfaces by Raman spectroscopy, organic compounds adsorbed on the hydrophobic surface were decomposed by the laser of the spectrometer, which imposes limitations on the laser power when using this method in characterizing hydrophobic surfaces of metals fabricated by laser processing.

Effect of Surface Coating Condition on High‐friction Organic Zinc‐rich Paints for HSFB Joints

AbstractWith the development of paints, high‐friction organic zinc‐rich paints with slip coefficients more than 0.45 have been advanced, making it possible to obtain more sophisticated and higher quality high strength bolted friction joints. Moreover, comparing to the inorganic zinc‐rich paints used at present, organic zinc‐rich paints are more appropriate for using in situ construction. However, since the application conditions of organic coatings have not been specified, it is recommended that a slip test should be carried out separately for each surface preparation to confirm the slip coefficient. In this study, slip tests were carried out on high strength bolted friction joint specimens to investigate the influence of high‐friction organic zinc rich paint film thickness and surface preparation on the slip coefficient. Furthermore, based on the experimental results, a surface preparation that can consistently produce a high slip coefficient is proposed.