Surface Properties Of Coatings Research Articles

Layer-by-layer, ultrasonic spray assembled 2D and 3D chemically crosslinked carbon nanotubes and graphene

Abstract

The influence of laser parameters on the hardness studies and surface analyses of laser alloyed stellite-6 coatings on AA 1200 alloy: a response surface model approach

The development of uniform microstructures with improved performance has been necessitated by the growing importance of Al-based alloys as materials for engineering applications. However, low hardness values limit the application alloys in industries. This research is aimed at enhancing the surface properties of Al-based stellite-6 coatings via laser alloying technique. A 4.4 kW Rofin Sinar Nd:YAG laser emitting 1.064 µm wavelength was used in this study. The laser power was varied in the range of 3–4 kW and the scanning speed in the range of 1.0–1.2 m/min. The optimum laser parameters gave a good metallurgical bonding obtained between substrate and reinforcement at laser power of 3 kW and scan speed of 1.0 m/min. The intermetallic compound and microstructure results in a significant increase in hardness values; which is about 33-times the hardness of the substrate (24 HV0.1). High residual stresses and crack formation were eliminated through optimisation of laser processing parameters, leading to enhanced quality of the coatings, surface adhesion between substrate and reinforcement materials, microstructural evolution and thus improved hardness property.

Evaluation of Surface Coating Properties with Rice Husk Black Liquor on Handsheet

Evaluation of Surface Coating Properties with Rice Husk Black Liquor on Handsheet

Surface and Mechanical Properties of Nanoparticulate Resin Coatings and Their Toxicological Characterization

AbstractA process chain to produce and characterize nanoparticulate, hydrophobic resin coatings was investigated. The investigated process stain could be used for sanitary applications, for instance. Nanocomposites might have a potential risk to humans and the environment. Thus, not only the manufacturing process, but also the achievable product properties were examined. Toxicological investigations with regard to the nanoparticle sizes and solid contents used were performed by investigating the impact of the nanoparticles on lung (A549 cells) and liver (HepG2 cells) cells. Results included showed that by using modified alumina the product properties could be improved in terms of hydrophobicity and mechanical properties and that alumina particles were nontoxic. However, cell viability was slightly affected by the nanocomposite extracts, depending on the applied particle size and concentration in the nanocomposites.

Površinske in protikorozijske lastnosti hidrofobnih in hidrofilnih TiO2 prevlek na jekleni podlagi

Površinske in protikorozijske lastnosti hidrofobnih in hidrofilnih TiO2 prevlek na jekleni podlagi

EXPERIMENTAL STUDY OF SURFACE PROPERTIES OF GAS-THERMAL COATINGS OF THE ROTOR OF DOWNHOLE DRILLING MOTOR

The article presents the results of experimental studies of the surface properties of gas-thermal spray coatings of the rotor downhole drilling motors. Was analyzed the adhesion and corrosion resistance of coatings, obtained as a result of putting various powders on steel of various grades. It was established experimentally that the substrate material of the examined steels has almost no effect on the adhesion of the coating.

Influence of Cu, Au and Ag on structural and surface properties of bioactive coatings based on titanium

In this work influence of copper, silver and gold additives on structural and surface properties of biologically active thin films based on titanium have been described. Coatings were prepared by magnetron sputtering method. During each process metallic discs (targets) - Ti and the additive (Cu, Ag or Au) were co-sputtered in argon atmosphere. Structural investigation of as-deposited coatings was performed with the aid of XRD and SEM/EDS method. It was found that all prepared thin films were homogenous. Addition of Cu, Ag and Au resulted in nanocrystalline structure. Moreover, influence of these additives on hardness and antibacterial activity of titanium coatings was also studied. Ti-Cu, Ti-Ag and Ti-Au films had lower hardness as-compared to Ti. According to AAS results the difference of their activity was related to the ion migration process. It was found that Ti-Ag and Ti-Au coatings had biocidal effect related to direct contact of their surface with microorganisms. In the case of Ti-Cu antimicrobial activity had direct and indirect nature due to efficient ion migration process from the film surface to the surrounding environment. Functional features of coatings such as wettability and corrosion resistance were also examined and included in the comprehensive analysis.

A chemical stability study of trimethylsilane plasma nanocoatings for coronary stents

Trimethylsilane (TMS) plasma nanocoatings were deposited onto stainless steel coupons in direct current (DC) and radio frequency (RF) glow discharges and additional NH3/O2 plasma treatment to tailor the coating surface properties. The chemical stability of the nanocoatings were evaluated after 12 week storage under dry condition (25 °C) and immersion in simulated body fluid (SBF) at 37 °C. It was found that nanocoatings did not impact surface roughness of underlying stainless steel substrates. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to characterize surface chemistry and compositions. Both DC and RF nanocoatings had Si- and C-rich composition; and the O- and N-contents on the surfaces were substantially increased after NH3/O2 plasma treatment. Contact angle measurements showed that DC-TMS nanocoating with NH3/O2 treatment generated very hydrophilic surfaces. DC-TMS nanocoatings with NH3/O2 treatment showed minimal surface chemistry change after 12 week immersion in SBF. However, nitrogen functionalities on RF-TMS coating with NH3/O2 post treatment were not as stable as in DC case. Cell culture studies revealed that the surfaces with DC coating and NH3/O2 post treatment demonstrated substantially improved proliferation of endothelial cells over the 12 week storage period at both dry and wet conditions, as compared to other coated surfaces. Therefore, DC nanocoatings with NH3/O2 post treatment may be chemically stable for long-term properties, including shelf-life storage and exposure to the bloodstream for coronary stent applications.

Fine-tuning of surface properties of dual-size TiO2 nanoparticle coatings

Abstract In this work, we focus on wetting and morphology properties of fluoroalkylsilane modified TiO 2 (FAS-TiO 2 ) and as-received TiO 2 nanoparticle coatings. TiO 2 nanoparticles of two sizes (30 nm and 300 nm) were spin coated onto steel substrate covered with 300 nm layer of epoxy via layer-by-layer (LbL) deposition until the desired wetting characteristics were achieved. Static water contact angles, advancing and receding contact angles and contact angle hysteresis were measured to evaluate the wetting properties of FAS-TiO 2 and as-received TiO 2 nanoparticle coatings. The morphology of coatings was analyzed with average surface roughness (S a ) measurements and SEM imaging. We have presented a simple step-like procedure to fabricate TiO 2 nanoparticle coatings with target wetting properties, either (super)hydrophobic or (super)hydrophilic. Order of the LbL deposition of dual-size nanoparticles for the fabrication of superhydrophobic/superhydrophilic coatings was found to be an important factor influencing on surface roughness and hence wettability. SEM images revealed a typical morphology and S a difference between FAS-TiO 2 and as-received TiO 2 nanoparticle coatings reflected in the discrepancy of the average size of the agglomerates that are coating the substrate. Based on these results we can fine-tune the surface roughness and wettability by controlling the LbL deposition of dual-size FAS-TiO 2 and as-received TiO 2 nanoparticles.

Surface properties of hard protective coatings studied by optical techniques

The paper describes optical study of SiC, C and NiC layers deposited on Si substrates by double beam ion sputtering (DBIS) method. The following optical methods: ellipsometry, bidirectional reflection distribution function (BRDF) and total integrated scattering (TIS) studies have been applied. The obtained results allowed us to determine the refractive indices, extinction coefficients and the roughness parameters of DBIS films. Also surface profiles of optical constants determined from scanning ellipsometric measurements have been presented. The power spectral density functions (PSD) of surface roughness for studied samples have been determined. The influence of the deposition technology on film topography has been discussed.

Influence of Material Composition on Structural and Optical Properties of HfO2-TiO2 Mixed Oxide Coatings

In this paper the influence of material composition on the structural, surface and optical properties of HfO2-TiO2 mixed oxide coatings was investigated and discussed. Five sets of thin films were deposited using reactive magnetron sputtering: HfO2, TiO2 and three sets of mixed HfO2-TiO2 coatings with various titanium content. The change in the material composition had a significant influence on the structural, surface and optical properties. All of the deposited coatings, except for (Hf0.55Ti0.45)Ox, were nanocrystalline with crystallites ranging from 6.7 nm to 10.8 nm in size. Scanning electron microscopy measurements revealed that surface of nanocrystalline thin films consisted of grains with different shapes and sizes. Based on optical transmission measurements, it was shown that thin films with higher titanium content were characterized by a higher cut-off wavelength, refractive index and lower optical band gap energy. The porosity and packing density were also determined.

Hydrophobicity of biofilm coatings influences the transport dynamics of polystyrene nanoparticles in biofilm-coated sand

Engineered nanoparticles (ENPs) are used in the manufacture of over 2000 industrial and consumer products to enhance their material properties and functions or to enable new nanoparticle-dependent functions. The widespread use of ENPs will result in their release to the subsurface and aquatic environments, where they will interact with indigenous biota. Laboratory column experiments were designed to understand the influence of two different Pseudomonas aeruginosa biofilms on the mobility of polystyrene latex nanoparticles in granular porous media representative of groundwater aquifers or riverbank filtration settings. The transport behavior of 20 nm carboxylate-modified (CLPs) and sulfate (SLPs) polystyrene latex ENPs suspended in NaCl or CaCl2 (1 and 10 mM ionic strength, pH 7) was studied in columns packed with quartz sand coated with biofilms formed by two P. aeruginosa strains that differed in cell surface hydrophobicity (P. aeruginosa 9027™, relatively hydrophilic and P. aeruginosa PAO1, relatively hydrophobic). Biofilm-coated quartz sand retained more of the electrostatically-stabilized latex ENPs than clean, uncoated sand, regardless of the serotype. As IS increased, clear differences in the shape of the ENP breakthrough curves were observed for each type of biofilm coating. ENP breakthrough in the P. aeruginosa PAO1 biofilm-coated sand was generally constant with time whereby breakthrough in the P. aeruginosa 9027 biofilm-coated sand showed dynamic behavior. This indicates a fundamental difference in the mechanisms of ENP deposition onto hydrophilic or hydrophobic biofilm coatings due to the hydration properties of these biofilms. The results of this study demonstrate the importance of considering the surface properties of aquifer grain coatings when evaluating ENP fate in natural subsurface environments.

Assessment of adhesion and surface properties of polyurethane coatings based on non-polar and hydrophobic soft segment

Abstract Polyurethane (PU)-based coatings attract much more attention in various applications due to their unique and versatile properties. Non-polar hydrophobic PU coatings are being extensively explored as advanced coatings. Here, a novel hydrophobic PU coating is synthesized based on combination of non-polar polyols, polypropylene glycol (PPG) and hydroxyl terminated polybutadiene (HTPB). The adhesion properties, micro-hardness and water uptake behavior of samples are characterized. The effect of composition (HTPB/PPG molar ratio) on the surface properties of synthesized PU coatings are analyzed by Fourier-transformed infrared spectrometry (FTIR-ATR), contact angle measurement and atomic force microscopy (AFM). Results show sample with 0.25% molar ratio HTPB has maximum lap shear strength and negligible water absorption. So, the synthesized PU coating with optimized composition could support enough adhesion to substrate and provide hydrophobic surface properties.

Superhydrophilicity and durability of fluoropolymer-TiO 2 coatings

Abstract Self-cleaning fluoropolymer-TiO2 coatings have been in focus as a promising group of materials for a number of years due to their favorable combination of photo-activated hydrophilicity and chemical resistivity of the Teflon-based material. The technology incorporates photocatalysis, which results in oxidation of organic compounds absorbed to a surface, with its superhydrophilic nature, which hinders further absorption of any non-polar substances. The main practical challenge concerning this subject is optimization of the coatings composition without compromising its stability and durability. The aim of this study was to characterize the superhydrophilicity (SHP) of a fluoropolymer-TiO2 coatings as a function of their composition, namely the amounts of polymer, type of the applied curing agent, and the amounts of the titania particles. The hydrophilicity of the coatings was compared to their surface structure and durability to withstand UV-light exposure. In this study, 24 combinations of coatings were studied with contact angle measurements, Fourier transform infra red spectroscopy (FTIR), and scanning electron microscopy (SEM). The results were analyzed statistically with general linear models (GLM) and multivariate data analysis (MDA). The contact angle measurements have shown that time was the most important variable influencing the surface properties of self-cleaning coatings. In terms of composition, the amount of polymer was of significance. Neither the curing agent, nor the amount of titanium dioxide seemed to have any lasting effect on SHP. The analysis of surface structure indicated that illumination influenced the organic polymer, and at long exposure times it led to the degradation of the polymer. This was confirmed by SEM analysis.

Surface properties of nanocrystalline TiO2 coatings in relation to the in vitro plasma protein adsorption

This study reports on the selective adsorption of whole plasma proteins on hydrothermally (HT) grown TiO2-anatase coatings and its dependence on the three main surface properties: surface charge, wettability and roughness. The influence of the photo-activation of TiO2 by UV irradiation was also evaluated. Even though the protein adhesion onto Ti-based substrates was only moderate, better adsorption of any protein (at pH = 7.4) occurred for the most negatively charged and hydrophobic substrate (Ti non-treated) and for the most nanorough and hydrophilic surface (HT Ti3), indicating that the mutual action of the surface characteristics is responsible for the attraction and adhesion of the proteins. The HT coatings showed a higher adsorption of certain proteins (albumin ‘passivation’ layer, apolipoproteins, vitamin D-binding protein, ceruloplasmin, α-2-HS-glycoprotein) and higher ratios of albumin to fibrinogen and albumin to immunoglobulin γ-chains. The UV pre-irradiation affected the surface properties and strongly reduced the adsorption of the proteins. These results provide in-depth knowledge about the characterization of nanocrystalline TiO2 coatings for body implants and provide a basis for future studies on the hemocompatibility and biocompatibility of such surfaces.

Surface properties of W-implanted TiN coatings post-treated by low temperature ion sulfurization

TiN coatings were implanted with W ions by metal vapor vacuum arc (MEVVA) source at dose of 9×1017ions/cm2, and then they were post-treated by low temperature ion sulfurization (LTIS) at 160°C. The W-implanted TiN samples were characterized before and after post-treatment of LTIS, using Scanning Electron Microscopy (SEM), Scanning Auger Microprobe (SAM), X-ray diffraction (XRD), and Nano Indenter System. Friction and wear properties were evaluated using a ball-on-disc tribometer under dry sliding in air. After post-treatment of LTIS, XRD results showed no diffraction peaks of tungsten sulfides on surfaces of W-implanted TiN coatings; W-implanted TiN coatings were sputtered by the sulfur plasma with about 36% reducing of W depth. Further, the nano-hardness decreased mainly due to the amount decreasing of Ti2N and the formation of more metal oxides on surfaces of W-implanted TiN coatings after LTIS. As a result, LTIS treatment could not well improve tribological properties of W-implanted TiN coatings.

On the role of hydrophobic Si-based protective coatings in limiting mortar deterioration.

In order to avoid both natural and artificial stone decay, mainly due to the interaction with atmospheric pollutants (both gases such as NOx and SO2 and particulate matter), polymeric materials have been widely studied as protective coatings enable to limit the penetration of fluids into the bulk material. In the current work, an air hardening calcic lime mortar (ALM) and a natural hydraulic lime mortar (HLM) were used as substrates, and commercially available Si-based resins (Alpha®SI30 and Silres®BS16) were adopted as protective agents to give hydrophobicity features to the artificial stones. Surface properties of coatings and their performance as hydrophobic agents were studied using different techniques such as contact angle measurements, capillary absorption test, mercury intrusion porosimetry, surface free energy, colorimetric measurements and water vapour permeability tests. Finally, some exposure tests to UV radiation and to real polluted atmospheric environments (a city centre and an urban background site) were carried out during a wintertime period (when the concentrations of the main atmospheric pollutants are higher) in order to study the durability of the coating systems applied. The effectiveness of the two commercial resins in reducing salt formation (sulphate and nitrate), induced by the interaction of the mortars with the atmospheric pollutants, was demonstrated in the case of the HLM mortar. Graphical Abstract ᅟ.

New Book on Chemistry, Materials and Properties of Surface Coatings

New Book on Chemistry, Materials and Properties of Surface Coatings

Surface properties of alicyclic epoxy coatings modified with reactive copolymer containing fluorinated side chains

An alicyclic epoxy resin was modified with a copolymer having both a perfluoroalkyl side chain and a cyclohexenoxide-terminated side chain. The copolymer had a good solubility in the epoxy matrix during the reaction of the alicyclic epoxy groups on the terminal end of the side chains. Thus, the cured epoxy resin had a homogeneous phase structure and was a colorless material with excellent transparency. The fluorinated side chains were highly self-segregated in the air-side surface (thickness: less than 8 nm) to minimize the interfacial free energy between the air and cured epoxy resin. The surface of the epoxy coatings had a significantly low surface free energy (ca. 20 mJ/m2) and revealed both high hydro- and oleo-phobicities. In addition, the surface had a gradient in the refractive index due to the self-stratification of the C–F bond that has a low polarizability.

Modification of epoxy-polyester and polyester powder coatings with silicone-acrylic nanopowders – effect on surface properties of coatings

The effect of modification with 3 wt % of nanopowders containing silicone-acrylic core-shell nanoparticles (size ca. 100 nm) on surface properties of epoxy-polyester and polyester powder coatings was investigated. Contact angle (CA) determinations, atomic force microscopy (AFM), confocal microscopy (CM), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), and X-ray photoelectron spectroscopy (XPS) were used to assess this effect. It was found that the modified coatings showed significantly higher CA values and significantly lower surface-free energy (SFE) values as compared to unmodified ones what could be explained by migration of silicone resin contained in nanopowder to the coating surface due to specific features of silicone polymer. Using XPS and EDS the presence of silicone on the surface was confirmed, and AFM of modified coatings revealed structures on the surface which could be attributed to nanoparticles of silicone resin. It was stated that the chemical structure of silicone resin influenced very much surface properties of the coatings.