A review on challenges,recent progress and applications of silica nanoparticles based superhydrophobic coatings

Over the past few decades, the study of superhydrophobic coatings (SHCs) gained the significant interest of worldwide researchers due to their tremendous applications in various sectors including, the metal industry, membrane industry, automation, structures, marine, defense, and medicines. The literature is full of review papers on the basics of SHCs, their synthesis methods, and their applications. But, minimal reviews are available on silica nanoparticles-based SHCs. However, silica nanoparticles are well-known material for SHCs due to their abundance, economical, transparency and ease of surface modification by various surface-functionalizing agents compared to other nanomaterials. Furthermore, silica nanoparticles are the most preferred material for the generation of nano-level roughness in the coatings to exhibit superhydrophobicity. Therefore, there is a great need to work in this direction. This work is dedicated to the challenges, recent progress and applications of silica nanoparticles-based superhydrophobic coatings.     

激光表面改性在金属基陶瓷涂层制备中的应用

概述了激光表面改性技术的基本原理,综述了激光表面合金化、激光熔覆、激光重熔和激光沉积等激光表面改性技术在金属基陶瓷涂层制备中的应用,对各项技术的原理、特点和国内外研究现状分别加以描述,最后指出激光表面改性技术在未来领域的发展方向。     

Adhesion of SiO2 thin films to plasma-treated SUS304 stainless steel substrates

The adhesion strength of the coated SiO₂ thin film to SUS304 stainless steel substrates with various surface treatment conditions is studied in this research. The surface of the SUS304 stainless steel substrate is first treated with 1000-W plasma and then a SiO₂ thin film is deposited onto the surface via radio-frequency magnetron sputtering. Scanning electron microscopy is employed to observe the surface and cross section of the coating and X-ray diffraction is used to analyze the crystallographic structure. Moreover, a nanoscratch test instrument was employed to examine the indentation, scratches, coating hardness, modulus of elasticity, coefficient of friction, and critical adhesion of the SiO₂ film and to obtain surface profiles. A comparison of the coating adhesion of the substrate surfaces with and without plasma treatment indicates that critical adhesion increases significantly after Ar/N₂/O₂ plasma treatment.     

Progress update on extending the durability of air plasma sprayed thermal barrier coatings

Air plasma sprayed thermal barrier coatings (TBCs) are widely used in gas turbines to provide thermal insulation for the metallic engine components. During service, the multi-layered and multi-material systems undergo thermal and mechanical degradation. The degradation mechanisms include sintering, phase transformation, residual stress, oxidation, erosion and CMAS attack. The degradation leads to the initiation and propagation of cracks at or near the interface between the topcoat and bond coat, eventually merging into large-scale delamination and resulting in failure of the TBCs. Recent progress in the development of methods for mitigating the detrimental impact of these failure mechanisms via composition and processing modifications has been reviewed. Meanwhile, the applications of newly-emerging materials with superior properties have also been discussed. The review emphasises the relationships between composition, microstructure and properties of TBCs, which is beneficial for the exploration of the advanced TBCs with higher durability.     

Effect of plasma sprayed and laser re-melted Al2O3 coatings on hardness and wear properties of stainless steel

Commercially available austenic stainless steel substrate was coated with commercially available, raw Al₂O₃ powder applied by means of plasma spraying method and then re-melted with CO₂ laser beam of various parameters. Tribological and mechanical properties of the 120 J/mm and 160 J/mm laser re-melted coatings were compared with the tribological and mechanical properties of the “as-sprayed” coating. The influence of the laser beam of various parameters on the microstructure, phase constituents, and mechanical and tribological properties of the ceramic coating was investigated by means of scanning electron microscopy, light microscopy, computer tomography, X-ray diffraction technique and nanoindentation tests. The micro sliding wear performance of the coatings was tested using a nanoindenter. The study showed an improvement of the mechanical and tribological properties caused by the laser treatment. The best results were achieved for coating re-melted with 120 J/mm laser beam.     

溶胶-凝胶法制备不锈钢表面SiO2-TiO2-Al2O3-ZrO2涂层

在乙醇中,分别以盐酸、醋酸为催化剂,以正硅酸乙酯、钛酸正丁酯、硝酸铝、氧氯化锆为金属醇盐前躯体,通过分步水解法制备了SiO2-TiO2-Al2O3-ZrO2复合溶胶,利用浸渍法将陈化后的复合溶胶涂覆到不锈钢表面制得透明的复合涂层。对SiO2-TiO2-Al2O3-ZrO2复合涂层进行了差热分析(DTA)、失重分析(TG)、红外光谱(IR)、X射线衍射分析(XRD)以及耐HCl、CuSO4和FeCl3溶液浸泡腐蚀实验。结果表明,涂层中存在TiO、SiO、AlO键的氧化物网状结构,其XRD图中出现了锐钛矿和板钛矿的相结构。该涂层致密,具有良好的耐蚀性能。     

超疏水、自清洁氟化石墨改性不锈钢网的油水分离研究

采用环氧树脂和氟化石墨（FG）纳米片对200目（75 μm）、300目（50 μm）和400目（37.5 μm）不锈钢网进行表面修饰改性,制备出具有超疏水、自清洁性能的氟化石墨改性钢网。正己烷-水、二氯甲烷-水、正癸烷-水、间二甲苯-水及柴油-水混合物可在自身重力下迅速通过氟化石墨改性钢网实现分离,且分离效率均在99.89%以上。同时,氟化石墨改性不锈钢网还具有良好的重复使用性能和机械耐久性能,在循环使用100次以及外力作用下磨损100次后,仍保持良好的超疏水性能。     

Effect of plasma pretreatment on the wrinkle‐resistance properties of cotton fibers treated with a 1,2,3,4‐butanetetracarboxylic acid–sodium hypophosulfite system with titanium dioxide as a cocatalyst

A 1,2,3,4‐butanetetracarboxylic acid (BTCA)–sodium hypophosulfite (SHP) wrinkle‐resistance system played an important role in improving the wrinkle‐resistance properties of cotton fibers. In this study, titanium dioxide (TiO₂) was used as a cocatalyst to further enhance the wrinkle‐resistance properties of BTCA–SHP‐treated cotton fabrics, that is, those treated with (1) 5% BTCA and 10% SHP; (2) 5% BTCA, 10% SHP, and 0.1% TiO₂; and (3) 5% BTCA, 10% SHP, and 0.2% TiO₂. In addition, the effect of plasma as a pretreatment process on the wrinkle‐resistance properties of the three treatment systems was also studied. The experimental results reveal that the wrinkle‐resistance properties of cotton fibers were improved after different wrinkle‐resistance treatments. In addition, the plasma pretreatment further enhanced the wrinkle‐resistance treatments to different extents, depending on the process parameters. Scanning electron microscopy images confirmed that such plasma pretreatment conditions imparted the best crosslinking effect on the cotton fibers. However, the wrinkle‐resistance‐treated cotton specimens had lower tensile strength and tearing strength values compared to the control sample, whereas the plasma pretreatment and cocatalyst may have compensated for the reduction in the mechanical strength caused by the wrinkle‐resistance agents. In this article, the optimum conditions for the plasma pretreatment on the basis of the result of the wrinkle‐recovery angle were analyzed with an L₉(3)³ orthogonal array testing strategy technique. The results showed that plasma treatment conditions with (1) a 10 mm/s speed, (2) a 0.1 L/min oxygen flow rate, and (3) a 4‐mm jet‐to‐substrate distance together caused a significant improvement in the wrinkle‐resistance properties of the cotton fibers treated with the three different BTCA treatments. Moreover, the treatment speed was the dominant factor, followed by jet‐to‐substrate distance and oxygen flow rate, in affecting the extent of improvement. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Design and development of TiC-reinforced 410 martensitic stainless steel coatings fabricated by laser cladding

AISI 410 martensitic stainless steel (MSS) coatings, reinforced with TiC ceramic particles of varying contents (0, 5%, 10% and 15%), have been fabricated by laser cladding technology for the first time in this study. The microstructure evolution and properties of the laser-cladded specimens are carefully investigated by advanced techniques, including XRD, SEM, TEM, EDS, a micro-hardness tester and a ball-on-disc tribological tester. The obtained results show that the as-cladded 410 MSS coating is mainly composed of coarse lath martensite (M), a few austenite (A) and M₂₃C₆. After addition of TiC ceramic particles, the lath-shaped M is significantly refined, meanwhile the nano-sized Ti-enriched ceramic precipitates (TiC and Ti(C,N)) are formed in the composite coatings. However, microcracks and pores occur in the laser-cladded coating with addition of TiC up to 15%. It is found that both the microhardness and wear resistance of the coatings are enhanced with an increasing TiC content, and the 10% TiC-reinforced coating exhibits the optimal comprehensive performance, with much higher microhardness and wear resistance in comparison to the TiC-free MSS coating. The remarkable properties of the TiC-reinforced 410 MSS coatings can be mainly ascribed to the synergistic effects of microstructural refinement, nano-precipitation hardening and second-phase strengthening.     

Surface modification of polytetrafluoroethylene films by plasma pretreatment and graft copolymerization to improve their adhesion to bismaleimide

BACKGROUND: Polytetrafluoroethylene (PTFE) is utilized in many engineering applications, but its poor wettability and adhesion properties with other materials have limited its use. The study reported was aimed at achieving surface modification of PTFE films by radiofrequency NH₃ and N₂ plasma treatment, followed by graft copolymerization, in order to improve the interfacial adhesion of PTFE and bismaleimide. RESULTS: X‐ray photoelectron spectroscopy results showed that a short‐time plasma treatment had a distinct defluorination effect and led to nitrogen functional group formation. The nitrogen chemical bonding form was different for NH₃ and N₂ plasma treatments. Under the same experimental conditions, the NH₃ plasma exhibited a better etching effect than did the N₂ plasma. Contact angle measurement showed an improvement in both surface energy and wettabliity by short‐time plasma treatment. The concentration of the surface‐grafted bismaleimide on PTFE increased after the plasma pretreatment. The lap shear strength between PTFE and bismaleimide increased significantly after surface modification. CONCLUSION: This study found that plasma treatment caused changes in surface chemistry, thus leading to an increase of the wettability of PTFE surfaces. Hence, the adhesion properties of PTFE with bismaleimide were significantly improved. Copyright © 2008 Society of Chemical Industry     

Vitroceramic coatings deposited by laser ablation on Ti-Zr substrates for implantable medical applications with improved biocompatibility

The influence of vitroceramic coatings deposited onto Ti-Zr alloy plates on the biological properties of the final biomaterials was investigated. In this regard, two vitroceramic masses, different from compositional point of view, were synthesized by a sol-gel route, being subsequently converted into ceramic targets, suitable for ablation experiments. The film depositions were conducted in oxidative atmosphere, on substrates heated at 300 or 400 °C. The coated samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy coupled with selected area diffraction and energy-dispersive X-ray spectroscopy, contact angle measurements and in vitro biological analyses (MTT cell proliferation assay, GSH oxidative stress assay, optical and fluorescence microscopy). All results sustained the applicative potential of Ti-Zr alloy substrates covered with a thin vitroceramic layer for medical implant applications.     

X-Ray photoemission study of plasma modified polyethylene surfaces

X-Ray photoelectron spectroscopy (XPS) was used to determine plasma induced chemical species on the surface of polyethylene (PE). Argon plasmas were found to have no detectable chemical effect on the PE surface, whereas oxygen and nitrogen plasmas created new chemical species which altered the chemical reactivity of the PE surface. Oxygen plasmas were found to react more rapidly with the PE surface than nitrogen plasmas. The degree of incorporation of new chemical species in the near surface region is approximately 20 at. % at the saturation level for both oxygen and nitrogen plasmas. Core level spectra for oxygen and nitrogen plasma treated PE suggest the formation of primarily C-O-C species in the former and C-N species in the latter. Angle-resolved XPS measurements indicate that the depth of incorporation of new chemical species is confined to the top 25 A.     

氩等离子体处理聚四氟乙烯粘接性能研究

利用氩等离子体表面处理后再经丙烯酸化学接枝处理方法对聚四氟乙烯(PTFE)薄片表面进行改性,发现PTFE对水的润湿性明显改善,然后用环氧胶进行粘接,其粘接强度有较大提高。     

Effect of oxygen and fluorine plasma surface treatment of silicon-incorporated diamond-like carbon coatings on cellular responses of mouse fibroblasts

The surface chemistry of silicon-incorporated diamond-like carbon (Si-DLC) was tailored utilizing oxygen and fluorine plasma treatments. Successful anchoring of oxygen and fluorine functional groups to the surface of Si-DLC was verified using X-ray photoelectron spectroscopy. The impact of surface modification of Si-DLC on hydrophobicity was correlated with the viability of L929 mouse fibroblasts. The confocal microscopy and viability results indicated that oxygen-treated Si-DLC showed increased cell viability compared to untreated Si-DLC and fluorine-treated Si-DLC samples 5 days after seeding. The increased cell viability was correlated with the conversion of the hydrophobic surface of Si-DLC into a hydrophilic surface by oxygen plasma treatment.     

Protective properties of organic phosphate-pigmented coatings on phosphated steel substrates

Investigations have been carried out on properties of coatings, differing by their pigmentation and binder, and applied on different chemical pre-treatments of the steel surface. Paints based on alkyd and alkyd-melamine binders, pigmented with zinc phosphate and modified basic zinc phosphate were applied on amorphous and crystalline phosphated steel surface and, for the comparison purpose, on degreased steel surface. The effect of the binder, the pigment and the pre-treatment of the steel surface on the protective properties of the coatings were determined by measurements of adhesion, water absorption and water permeability and by results obtained in salt spray and Prohesion tests. Coatings based on alkyd binder show a lower damage degree and good retention of adhesion in corrosion conditions, in spite of a higher water absorption and water permeability and a lower initial adhesive strength. Protective properties of coatings have been found to be highly dependent upon the substrate pre-treatment. Chemical pre-treatment of the steel substrate increases the protective properties of the system, which is particularly evident in the case of crystalline phosphating and the coating pigmented with modified basic zinc phosphate. This phenomenon can be explained by the synergism between this phosphate pigment with crystalline phosphate layer.     

Thermal shock resistance of thermal barrier coatings modified by selective laser remelting and alloying techniques

Aiming to improve the thermal shock resistance of thermal barrier coatings (TBCs), the plasma-sprayed 7YSZ TBCs were modified by selective laser remelting and selective laser alloying, respectively, in this study. A self-healing agent TiAl₃ was introduced into the 7YSZ TBCs by selective laser alloying to fill cracks during thermal cycling. The thermal shock experiments of the plasma-sprayed, laser-remelted, and laser-alloyed TBCs were conducted by a means of heating and water-quenching method. Results revealed that some segmented microcracks were distributed on the surface of the laser-remelted and the laser-alloyed zones, showing a dense columnar crystal structure. After thermal shock tests, the numbers of segmented microcracks on the laser-remelted coating increased, whereas, in the laser-alloyed condition, some irregular particles formed, leading to the decreased numbers of segmented microcracks. The laser-alloyed coating exhibited the best thermal shock resistance, followed by the laser-remelted condition, with the thermal shock lifetime 3.3 and 2.7 times higher than that of the as-sprayed coating, respectively. On the one hand, both columnar grains and segmented microcracks in the laser-treated zone could effectively improve the strain tolerance of coatings. On the other hand, the oxidation products of TiAl₃ under high-temperature condition could seal the microcracks to postpone the crack connection. Thus, the thermal shock resistance of the laser-treated coatings was significantly improved.     

抗菌不锈钢研究现状

综述了近几年国内外各种抗菌不锈钢的研究进展。介绍了复合抗菌不锈钢、涂层抗菌不锈钢、表面改性抗菌不锈钢以及合金型抗菌不锈钢的抗菌原理、特点、制造工艺,并展望了其应用前景。     

XPS study of the PET film surface modified by CO2 plasma: effects of the plasma parameters and ageing

Chemical modification of the PET surface by carbon dioxide plasma treatment has been studied using X-ray photoelectron spectroscopy (XPS). The plasma process results mainly in the formation of carbonyl, carboxyl, and carbonate groups at the PET surface. Under rather mild treatment conditions (low plasma power combined with a short treatment time), the formation of C-O bonds was found to be dominant, whereas the formation of highly oxidized carbon or double-bonded oxygen-containing groups required a high plasma power or a relatively long treatment time. The treatments performed under excessive conditions frequently led to degradation at the polymer surface. Angle-resolved XPS analyses performed on a freshly modified PET film showed a slight decrease in the O/C atomic ratio when the take-off angle (TOA) increased, indicating a relatively uniform distribution of oxygen within the sampling depth (estimated to be about 8 nm at 80° TOA). The chemical composition of the plasma-modified surface was found to be relatively stable on extended storage in air under ambient conditions. The decrease in oxygen-containing groups at the carbon dioxide-plasma-treated PET surface upon ageing is mainly ascribed to the surface rearrangement of macromolecular segments, the loss of oxygen-containing moieties introduced by the plasma treatment, and the possible migration of non-affected PET chains from the bulk to the surface region.     

Development of poly(vinylcarbazole)/alumina nanocomposite coatings for corrosion protection of 316L stainless steel in 3.5% NaCl medium

Poly(vinylcarbazole) (PVK) and PVK‐alumina (Al₂O₃) nanocomposite coatings were electrochemically coated on 316 L stainless steel (SS) substrates for corrosion protection of 316 L SS in 3.5 weight (wt) % NaCl medium. The formation of PVK and incorporation of nanoalumina particles in PVK‐Al₂O₃ nanocomposite coatings were confirmed from attenuated total reflectance‐infrared spectroscopy (ATR‐IR). Thermal analysis (TG) results showed enhanced thermal stability for the composites relative to PVK. Incorporation of Al₂O₃ nanoparticles enhanced the micro hardness of PVK coated 316 L SS. The dispersion of alumina nanoparticles was examined via scanning electron microscope (SEM) and tunneling electron microscopy (TEM) and revealed distinct features. The influence of nanoparticles on the barrier properties of PVK and PVK‐Al₂O₃ nanocomposites was evaluated in aqueous 3.5 wt % NaCl by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies. The results proved that PVK nanocomposite coatings provided better protection for 316 L SS than PVK coatings. The drastic increase in impedance values is due to the high corrosion resistance offered by the PVK nanocomposite coatings that arises due to the interaction between Al₂O₃ nanoparticles and PVK. The highest corrosion protection shown by the 2 wt % nano Al₂O₃ incorporated PVK composite coatings proved enhanced corrosion resistance compared to PVK. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44937.     

Surface modification of polypropylene membrane by low‐temperature plasma treatment

Microporous polypropylene membranes were low temperature plasma treated with acrylic acid and allylamine. Parameters of plasma treatment were examined and optimized for the enhancement of membrane performance properties. Excess power damaged the membrane surface and excess monomer flow rate increased the reactor pressure to interfere with the glow discharge. Longer plasma treatment time resulted in even more plasma coating and micropore blocking. The contact angle with water decreased and wettabilities increased with the increase of plasma treatment time. Deposition of the plasma polymer on the membrane surface was confirmed by FTIR/ATR spectra of the treated surface. In determining the flux, the hydrophilicity of the surface played a role as important as that of the micropore size. Adequate plasma treatment could enhance both water flux and solute removal efficiency. Results from the BSA (bovine serum albumin) solution test confirmed that fouling was greatly reduced after the plasma treatment. The BSA solution flux through the plasma‐treated membranes depended on pH, whereas pH variation had no serious effects on the untreated membrane. Modification of the surface charge by the plasma treatment should exert a substantial influence on the adsorption and removal of BSA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1555–1566, 2001