Journal of Coatings Technology and Research最新文献

Plasma treatment is a technique accepted universally for improving the adhesion of coatings to substrates because of its ease of use, environmental friendliness, and its adaptability. Hence, this research aims to further explore this technique and specifically investigate the effect of air–plasma treatment of different substrates (stainless steel, copper, brass, titanium, and aluminum) on the adhesion and tribological properties of an ultra-high molecular weight polyethylene polymer coating deposited on them. Several characterization techniques such as X-ray photoelectron spectroscopy, water contact angle, and roughness measurements are conducted to evaluate the surfaces before and after air–plasma treatment. Results showed that UHMWPE coating deposited on the plasma-treated stainless steel substrates demonstrated the best adhesion and tribological properties. This was attributed to the improved oxidation effect and the carbon cleaning effect of the plasma treatment on the stainless steel substrates as compared to other substrates.

In this paper, the reflectance spectra of a series of black coated fabrics were decomposed to a limited number of feasible spectra that could be collected as optimal primaries. In fact, the possibility of finding the optimal feasible vectors with the capability of matching the spectral space of black samples was investigated. In this way, the application of non-negative matrix factorization (NNMF) method was examined on spectral dataset of 363 black coated fabrics to derive the non-negative basis functions. The extracted primaries were then employed for spectral matching of black samples where, one to three non-negative spectra were employed as optimal colorants. Results showed that both the spectral and colorimetric reconstruction errors decreased by increasing the number of primaries while applying of 3 non-negative feasible bases could mimic the spectral behaviors of black samples well. Besides, the role of chromatic primaries in two and three bases system was found very important due to better replication of reflectance spectra that matches the tint effect of blacks.

Nanocomposite coatings have been extensively used in the manufacture of automotive components to protect against corrosion of steel structures. The (3-mercaptopropyl) tris[2-(2-methoxyethoxy) ethoxy] silane (MPTMEES) functionalized Cr₃C₂ was encapsulated with graphene oxide (GO) as an efficient nanofiller in the epoxy matrix (EP). The silanized chromium carbide wrapped in graphene oxide was tested by SEM/EDX and TGA. Electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) were used to study the protective performance of epoxy coating on steel in the presence of varying weight percentages of graphene oxide wrapped silanized chromium carbide in seawater. After 1 h of immersion, the coating resistance of EP-MPTMEES/Cr₃C₂ was determined to be over 43% higher than that of pure matrix. After 240 h in seawater, EIS tests revealed that EP-GO/MPTMEES-Cr₃C₂ nanocomposite coatings had a higher coating resistance (6340 kΩ.cm²) than ordinary epoxy (1.2 kΩ.cm²) coatings. Because of the coated substrate’s improved resistance to anodic dissipation, the least dissipation of ferrous ions was found at the crack of the EP-GO/MPTMEES-Cr₃C₂ nanocomposite coated steel specimen (1.5 I/nA). The silanized Cr₃C₂ was reinforced in the degradation products, forming an excellent passive layer at the coating/steel contact, according to FE-SEM/EDX analysis. The newly developed EP-GO/MPTMEES-Cr₃C₂ nanocomposite coating had improved corrosion protection and enhanced hydrophobic characteristics (WCA: 146°), according to the findings. The epoxy matrix with graphene oxide wrapped silanized chromium carbide demonstrated improved adhesive capabilities.

Cathodic electrophoretic deposition (CED) coatings are inevitably scratched following their application in processes such as automotive finishing. Self-healing coatings possess the ability to repair micro-scale damage, thereby extending their service life and reducing maintenance costs. Here, a novel strategy was developed to synthesize room-temperature intrinsic self-healing CED coatings by inserting 2-aminophenyl disulfide (APDS) into the polymer chain of cationic waterborne polyurethane (CWPU). Emulsion films incorporating the disulfide (SCWPU) could self-heal at room temperature via dynamic disulfide bond exchange and hydrogen bonding interactions, and their structures were confirmed by FTIR and Raman spectroscopy. The thermal properties of the SCWPU films were determined by differential scanning calorimetry and thermal gravimetric analysis. The effects of APDS incorporation and hard segment content (HSC) on the self-healing ability, mechanical and emulsion properties of the SCWPU films were systematically investigated. The results showed that the self-healing abilities of SCWPU film were 97.2% at RT over 24 h and 96.5% at 37°C (body temperature) after 4 h. CED coatings (8 μm, 3H pencil hardness) prepared from SCWPU emulsion also displayed self-healing properties at room temperature.

Two non-isocyanate polyurethanes (NIPUs) were used as reactive diluents for an alkyd to obtain eco-friendly new UV-curable alkyd-polyurethane coatings. A linseed-based alkyd resin was prepared and formulated with the reactive diluents (NIPUs) and free radical photoinitiator, and then UV-cured. NMRs were used to characterize the alkyd and NIPUs and glass transition temperature (T_g) of cured alkyd-polyurethanes were evaluated by using DSC. Further, spectroscopy and thermal stability of the coatings were evaluated by using ATR-IR spectroscopy and thermogravimetric analysis (TGA), respectively. Moreover, coating properties such as pencil hardness, cross-cut adhesion, pull-off adhesion, impact resistance, and reverse impact resistance were also evaluated. It was found that crosslink density, pencil hardness, adhesion, and T_g were dependent and proportional to the amount of the NIPUs (reactive diluents) showing significant improvement in mechanical and thermal properties compared to the linseed-based alkyd resin.

In this work, tannic acid (TA) was employed to modify the surface of multiwall carbon nanotubes (CNTs) to form TCNTs hybrids via noncovalent functionalization to enhance its dispersibility in water. Then, the TCNTs enhanced epoxy coatings were applied on sintered NdFeB magnets by cathodic electrophoretic deposition method for corrosion test. The corrosion resistance of prepared specimens was assessed by electrochemical experiments. The results show that TCNTs hybrids present a more homogeneous distribution in epoxy resin than pristine CNTs and could obviously promote anticorrosion properties of prepared specimens. Within 36-day soaking in 3.5 wt.% NaCl solution, the specimens maintain a high value of |Z|_0.01Hz (10⁸ Ω cm²) when the concentration of TCNTs is 2 g/L. When immersed in 3.5 wt.% NaCl solution for 40 days, the E_corr of specimens shifts to − 0.207 V and J_corr is about 5.281 × 10⁻¹¹ A cm⁻², which demonstrates superior corrosion resistance.

Cotton (CO) fabrics with flame retardant properties based on ionic liquids: 1-methyl-3-(-((triethoxysilyl)oxy)propyl)-1H-imidazol-3-ium chloride (MCPTS) and 1-(3-(triethoxysilyl)propyl)pyridine-1-ium chloride (PCPTS) with boron from boric acid are successfully obtained via a sol-gel process. Fourier transform infrared spectroscopy (FTIR), optical microscopy analysis, and scanning electron microscopy (SEM) images, were first carried out to characterize the chemical composition and the morphology of the treated and untreated cotton fabrics, respectively. The investigation of flame resistance was evaluated by the vertical burning test. It was observed that the treated cotton fabrics exhibited good flame-retardant properties and did not burn even after 10 s flame application duration and the rate of flame spread was inhibited compared to the pristine cotton fabric. Furthermore, the thermal comportment of cotton fabrics was analyzed by thermogravimetric (TG) analysis and differential scanning calorimeter (DSC). Moreover, the tensile strength of the treated textiles is mostly reserved. In this work, we prove that the sol-gel method using ionic liquids and boron could be used as an effective flame retardant to develop finishing cotton fabrics for textile fireproof applications.

Graphical abstract

Gloss is one of the main attributes to describe the appearance of surfaces and objects, as it contributes to the general quality perception. Gloss is a multidimensional quantity of which ‘specular gloss’ is the most commonly applied attribute. Specular gloss meters are standardized and widely used in industry. However, their readings correlate only partially to the general visual gloss impression, which also comprises distinctness-of-the-reflected-image (DOI), haze, contrast and surface-uniformity attributes. This study presents a more profound image-based gloss meter (iGM) which incorporates a CMOS camera detector. This concept is not new, but limited research has been conducted on the inclusion of various image processing evaluations for gloss attributes. The designed iGM is compatible to 60° specular gloss meter standards. The CMOS detector captures the reflected source image, which is processed to measure four perceptual attributes of surface gloss. The obtained results validate the 60° specular gloss evaluation and indicate a promising capability in characterizing DOI, haze, and contrast. Contrast is an important attribute that is not available yet in industrial gloss meters. It is measured using a diffuse aspecular light source. Generally, this iGM maintains the hardware principles of specular gloss meters, while evolving toward a representative gloss perception meter.

Corrosion resistance and active protection performance of organic coatings can be improved by incorporation of corrosion inhibitor-loaded nanocontainers. Herein, 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (FTES) as a green corrosion inhibitor was encapsulated in hollow mesoporous silica (HMS). FTES-loaded HMS (FHMS) was embedded in an epoxy coating on the surface of the magnesium (Mg) alloy. Artificial defect in FHMS-loaded epoxy coating was made by needle punching. The long-term anticorrosion behavior and self-healing properties of the modified coating were evaluated by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). In all cases, FHMS can enhance corrosion resistance of the epoxy coating. Among all the FHMS-loaded coatings, the coating containing 0.5 wt% FHMS (FHMS-0.5%) still exhibits excellent corrosion protection performance after 2688 h of immersion. Meanwhile, it shows superior self-healing ability in the scratched areas. These are attributed to the fact that FTES released from HMS nanoparticles can interact with the epoxy coating and the Mg alloy substrate. Moreover, FTES silane can also form a crosslinked Si-O-Si network by itself.