Coatings

In recent years, core–shell composite particles with organic polymer as the core and inorganic SiO₂ as the shell have attracted widespread attention and prompted robust scientific endeavors. The encapsulation of SiO₂ can endow the polymer core with a variety of important properties, and is of great significance for the synthesis of multi–functional materials, having favorable application prospects in coating, polishing, medical, optical, magnetic, lubrication and other fields. In this paper, the recent advances in the preparation of core–shell [email protected]₂ composite particles are reviewed. From the perspective of interface bonding mechanisms between the core and the shell, this paper mainly focused on the following five aspects: Pickering stabilization, acid–base interaction, charge interaction, bridging of coupling agent, hydrogen bonding, and other actions. Additionally, applications of core–shell [email protected]₂ particles are also discussed. It is expected that this article can provide scientific guidance for the preparation of [email protected]₂ core–shell particles, further enriching their species and broadening their applications. Full article

This study aims to systematize the knowledge about innovative solutions to understand the composition of packaging materials and bioactive substances used in the packaging processes of meat and meat products, given the contemporary trends and consumer expectations. In edible packaging, the application of natural and renewable biopolymers is gaining popularity as, unlike petroleum-based plastic packaging materials, they do not cause environmental problems. Packaging using active compounds further extends the shelf life of food products compared with traditional packaging by reducing the adverse effects during storage, such as oxidation, microbial growth, and moisture loss. On the other hand, the inclusion of natural bioactive substances in packaging provides an opportunity to increase the shelf life of food products and/or decrease the use of preservatives. This direction offers a wide field for research due to the multitude of substances, their impact, and the properties of the packaged product. Full article

The amorphous AlTiCrFeMoSi high entropy alloy (HEA) coating with high hardness (11.88 GPa) is successfully deposited on T91 substrate by the magnetron sputtering method. Both T91 steel and as−deposited AlTiCrFeMoSi coating samples are exposed to a static liquid lead−bismuth eutectic (LBE) at 550 °C for up to 2000 h. The coating exhibits excellent corrosion resistance against lead−bismuth eutectic (LBE) compared with the uncoated T91 steel. The results show that the AlTiCrFeMoSi HEA coating has great potential in LBE−cooled fast reactor application. Full article

The performance of steel fibers reinforced RPC has a great relationship with the aspect ratio of the fibers. It is necessary to systematically study the relationship between the aspect ratio and the mechanical properties of RPC and the force-electricity response. In this paper, the flexural strength, the compressive strength and the flexural toughness and AC electrical resistance and AC impedance spectroscopy of reactive powder concrete are investigated. The flexural strength, compressive strength, and flexural toughness with the curing age of 1 day and 28 days are tested. The cement is the compound cement in this study, and the mass ratio of ordinary portland cement and sulphoaluminate cement is 1:1, and two kinds of steel fibers with aspect ratios of 30(AR-30) and 75(AR-75) are used. The fiber content is 2% of the concrete volume. Scanning electron microscope (SEM) and scanning electron microscope energy spectrum analysis (EDS) are investigated to analyze the composition of the hydration products. It can be obtained from the research results that the flexural strength and the compressive strength of reactive powder concrete decrease with the increase of steel fibers content with an aspect ratio of 30. The decreasing rates of the flexural strength and the compressive strength with the curing age of 1 d and 28 d are 14.93%~83.26% and 0.40%~46.36% with the incorporation of steel fibers with an aspect ratio of 30. The flexural toughness decreases in the form of a quadratic function with the mass ratio of steel fibers with an aspect ratio of 30. The electrical resistance of reactive powder concrete increases with the increase of steel fibers with an aspect ratio of 30. The maximum decreasing rate of electrical conductivity is 91.16%. The AC impedance spectrum is obtained, and the electric circuit of reactive powder concrete accords with the series conduction model, which parallel electrical resistance and capacitance of pore solution, rapid strength RPC and steel fibers respectively connect with a contact resistance of the electrode and specimens. It is found that the steel fibers network with an aspect ratio of 75 is closer by studying the equivalent circuit diagram. Full article

The optical qualities of cutting-edge aesthetic dental ceramics are crucial for great aesthetics and may be impacted by various bleaching methods. The objectives of this study were to evaluate how home bleaching affected the translucency parameter (TP), contrast ratio (CR), total color difference (ΔE), and surface roughness (Ra) of various aesthetic dental ceramics, including innovative ultra-translucent zirconia. The three varieties of ceramics that were tested—IPS e.max-Press (IPS); classic zirconia with feldspathic layering (LZr); and translucent zirconia (TZr)—were each represented by seven samples. The samples were bleached at home using 15% carbamide peroxide for six hours a day for seven days. Each specimen’s pre- and post-bleaching CIE L*a*b* values were measured using a spectrophotometer, and the TP, CR, and ΔE were determined. Ra values were measured via 3D profilometry. In comparison to the pre-stage results, statistical analysis showed a significant decrease in TP and increase in CR for LZr and TZr in the post-stage (p < 0.05), but not for IPS (p = 0.398). The results also showed substantial variations in ΔE for the three ceramics (p = 0.020). Ra readings during the post-stage were noticeably greater than those at the pre-stage (p = 0.018). Home bleaching had an impact on the optical characteristics and surface texture of the dental ceramics. Additionally, IPS had greater color stability than LZr and TZr. Full article

Titanium nitride (TiN) thin films deposited by high-power pulsed magnetron sputtering usually have a high compressive residual stress, which is not conducive for the adherence of TiN thin films. This study investigated the potential of Ti₂AlN for releasing the compressive residual stress of HPPMS-deposited TiN thin films and evaluated the adherence strength and hardness of TiN/Ti₂AlN multilayers by introducing the Ti₂AlN MAX phase to form TiN/Ti₂AlN multilayers. The results showed that smooth TiN/Ti₂AlN multilayers with the TiN (111) and Ti₂AlN (002) textures were successfully synthesized by HPPMS deposition and subsequent vacuum annealing. The compressive residual stress in TiN was released by Ti₂AlN. The adherence strength of the TiN/Ti₂AlN multilayers was improved after the release of the compressive residual stress, and the hardness of TiN/Ti₂AlN multilayers was close to the annealed TiN. This study provides a novel approach for releasing the residual stress of hard ceramic thin films using the MAX phase. Full article

Cr-doped Co₃O₄ thin films were prepared by spray pyrolysis on soda-lima glass. The structure and morphology of the prepared samples were characterized by grazing incidence X-ray diffraction (GIXRD), Fourier-transform infrared spectroscopy (FTIR) and Scanning electron Microscopy (SEM). The results indicated the formation of a single cubic spinel phase with a crystallite size of about 6 nm. Different electronic transitions and estimations of the band gap structure were determined from the optical absorption spectra. The dependence of electrical resistivity on Cr content was investigated. It was found that the resistivity increased by increasing the Cr content. In addition, the effect of photon excitation on the electrical properties showed that the electrical resistivity decreased under visible illumination (λ_vis. = 532 nm) and increased under infrared illumination (λ_IR = 780 nm). The relative change in resistivity (sensitivity) under both light illuminations was enhanced by increasing the Cr content. Therefore, this work introduces a new application for Co₃O₄ material as a light detector. Full article

At present, in order to comply with the development of the “the Belt and Road Initiatives”, the country is accelerating the pace of construction and increasing the demand for construction river sand. However, the quality of construction river sand is uncontrollable, and its shape is very similar to that of weathered sand. Therefore, using inferior weathered sand and mixed sand as inferior substitute sand in the market is prohibited, resulting in an increase in the difficulty coefficient of quality control of concrete fine aggregate in actual projects. This lays hidden dangers for the construction quality of the project. It is urgent to improve the quality control, testing, and detection process of river sand. Due to the long-term weathering of weathered sand, its density is small, and there are many pores, which leads to the material’s water absorption rate is higher than that of standard sand and river sand during fluidity tests. This paper takes this as a breakthrough point, reveals the variation law of fluidity loss under different variables, and explores a method for effectively screening low-quality sand and gravel. Through the silt content test (screening and washing method), the low-quality sand is preliminarily screened out, the mortar ratio is designed, and the fluidity test is carried out to compare the difference in fluidity loss of different types of mortar; determine the loss threshold range (mobility loss ≤ 15 mm) according to the mobility test results of the control group, and determine the qualification standard by comparing the measured mobility loss of the unknown sample with the loss threshold range. When the mobility loss is within the loss threshold range, the sample is qualified river sand. Otherwise, it is weathered sand or chowder sand. This method establishes a complete detection scheme for distinguishing weathered sand and river sand through mud content tests and mobility loss tests, solves the difficult problem of river sand quality control in engineering applications, and effectively eliminates the phenomenon of using low-quality weathered sand as river sand in the sand and gravel material market, thus avoiding congenital defects in concrete homogeneity. Full article

Ice accumulation on atmospheric structures will result not only in inconvenience to human activities, but also various catastrophic events. Many anti-icing coatings have been developed for anti-ice accretion on various atmospheric structures. However, such mitigating icing performances and developments in practical applications are restricted by various factors. Therefore, current mitigating icing coatings are far from practical implementation. Rough and smooth hydrophobic coatings have demonstrated their potential for mitigating ice formation. To advance the development of mitigating icing coatings, a perspective of hydrophobic coatings for mitigating icing is in need. Herein, this paper categorizes the mitigating icing coatings by their wettability firstly. Then, we recap the state-of-the-art hydrophobic coatings for mitigating icing. Afterwards, we point out the deficiency and limitations of current coatings for anti-icing. At last, we provide a perspective of future trends and development directions. This perspective review can guide the design of mitigating icing coatings towards practical implementation. Full article

Silica nanoparticles (SiNPs) are a promising material for nanomedicine technology. SiNPs are considered a powerful tool for drug delivery, functional coatings and films, and biomolecule separation due to their stability, biocompatibility, and accessible surface modification. Herein, the synthesis of SiNPs and SiNPs nylon 6 (SiNPs-Nylon) coated nanocomposites was proposed. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used for morphology, size, and stability analysis. Anticancer drug doxorubicin (DOX) loading to the nanocomposites and pH-dependent release experiments are presented. DOX-loaded nanocomposites with high drug capacities of up to 258 μg/mg (DOX/SiNPs) and 493 μg/mg (DOX/SiNPs-Nylon) show effective inhibition of A549 and HEK 293FT cell lines. The IC50 values were 0.08 ± 0.01 µM in terms of DOX amount and recalculated as 0.31 ± 0.04 µg/mL in terms of the concentration of SiNPs for the HEK 293FT cells. Therefore, silica nanocomposites have a high potential for cancer treatment. Full article

In this work, we report a unique and facile approach to the manufacture of fluorine-free superamphiphobic paper. Based on the principle that Fe₃O₄ nanoparticles (NPs) arranged along the direction of a magnetic field, the mixture of Fe₃O₄ NPs and polydimethylsiloxane (PDMS) was coated on kraft paper through self-assembly and thermal-curing at a high temperature in a magnetic field, fabricating a mushroom-like microstructure on the paper. At an Fe₃O₄ NPs content of 75%, the radius of the mushroom-like pillar caps (R_CAP) and center-to-center spacing between two pillars (S) obtained the optimal size of 37 ± 18 μm and 237 ± 38 μm, respectively. The oil-contact angle and water-contact angle of the fabricated paper were up to 156° and 160.4°, respectively. It also showed excellent oleophobic stability; the oil-contact angle was still maintained at 141.9° after 1 h. In addition, the contact angles of milk, ethylene glycol and castor oil were all above 150°, and the contact angle of diiodomethane was 134.2°. Moreover, the sample showed great oil resistance with a kit rating value of 12/12 and permeability of 1800+ s. Full article

Alumina dispersion-strengthened 316L stainless steels were successfully produced using attrition milling and spark plasma sintering. Two different composites (316L/0.33 wt% and 316L/1 wt% Al₂O₃) were prepared by powder technology. The attrition milling produced a significant morphological transformation of the globular 316L starting powders and provided a homogeneous distribution of the nanosized alumina particles. The XRD results confirmed that the 316L steel was an austenitic γ-Fe₃Ni₂. The formation of a ferrite α-Fe phase was detected after milling; this was transformed to the austenitic γ-Fe₃Ni₂ after the sintering process. The addition of nanosized alumina particles increased the composites’ microhardness significantly to 2.25 GPa HV. With higher amounts of alumina, the nanosized particles tended to agglomerate during the milling process. The friction coefficient (FC) of the 316L/0.33 wt% Al₂O₃ and the 316L/1 wt% Al₂O₃ decreased because of the increase in the composite’s hardness; FC values of 0.96, 0.93 and 0.85, respectively, were measured respectively for the 316L reference, the 316L/0.33 wt% and the 316L/1 wt% Al₂O₃. The 316L/0.33 wt% Al₂O₃ composite had a higher flexural strength of 630.4 MPa compared with the 316L/1 wt% Al₂O₃ with 386.6 MPa; the lower value of the latter was related the agglomeration of the alumina powder during attrition milling. Full article

Residual stresses are a major problem in SLM forming of large-sized parts of high-performance materials. The purpose of this study is to investigate the effects of scanning strategy, preheating temperature, and heat treatment on residual stresses in SLM formed high-strength steels. An experimental method was used to investigate the residual stresses in SLM forming of high-strength steels. The peak and distribution of residual stresses can be changed by optimizing the scanning strategy. The most suitable scanning method is the strip rotation scanning strategy. The optimum substrate preheating temperature is 200 °C, and the residual stress of SLM forming can be significantly reduced by 62.5%. The annealing temperature has a clear effect on the residual stress release, and also has an impact on the microstructure and mechanical properties. After annealing treatment at 550 °C for 3 h, the residual stresses can be effectively released, while the uniformity of microstructure and mechanical properties is improved. Finally, the control strategy of residual stress, microstructure and mechanical properties of 24CrNiMo high-strength steel was obtained. Full article

DLC (diamond-like carbon) films were prepared on Ti/PMMA(polymethyl methacrylate) under the different bias; the principal purpose of this study is to explore structural differences of films on Ti/PMMA with and without conductive material, and to further clarify the role of the conductive Ti interlayer in influencing the deposition mechanism. The results indicate that the films deposited on Ti/PMMA with conductive material exhibit uniform DLC structure and mechanical hardness when the bias voltage is ≥550 V. Furthermore, the deposited DLC does not change the wettability of PMMA, while the addition of the Ti interlayer virtually increases the risk of peeling off of the film. The results of the tribological study demonstrate the films on Ti/PMMA with conductive material have better tribological properties than those without conductive adhesive. This research work can provide basic theoretical guidance for depositing uniform DLC films on PMMA and even on all non-conductive substrates. Full article

To reduce the formation of detrimental complex oxides, bond coatings in the thermal barrier coatings for gas turbines are typically fabricated using vacuum plasma spraying (VPS) or the high-velocity oxygen fuel (HVOF) process. Herein, VPS and HVOF processes were applied using NiCoCrAlY + HfSi-based powder to assess the oxidation behavior of the bond coatings for both coating processes. Each coated sample was subjected to 50 cyclic heat treatments at 950 °C for 23 h and cooling for 1 h at 20 °C with nitrogen gas, and the weight change during the heat treatment was measured to evaluate the oxidation behavior. After the oxidation test, the coating layer was analyzed with X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The VPS coating exhibited faster weight gain than the HVOF coating because the alumina particles generated during the initial formation of the HVOF coating inhibited oxidation and diffusion. The VPS coating formed a dense and thick thermal growth oxide (TGO) layer until the middle of the oxidation test and remained stable until the end of the evaluation. However, the HVOF coating demonstrated rapid weight loss during the final 20 cycles. Alumina within the bond coat suppressed the diffusion of internal elements and prevented the Al from being supplied to the surface. The isolation of the Al accelerated the growth of spinel TGO due to the oxidation of Ni, Co, and Cr near the surface. The as-coated VPS coating showed higher hardness and lower interfacial bonding strength than the HVOF did. Diffusion induced by heat treatment after the furnace cyclic test (FCT) led to a similar internal hardness and bonding strengths in both coating layers. To improve the quality of the HVOF process, the densification of the coating layer, suppression of internal oxide formation, and formation of a dense and uniform alumina layer on the surface must be additionally implemented. Full article

Given the growing global demand for high-performance microcomponents, while keeping the size of the microcomponents as small as possible, several manufacturers have chosen to increase the number of thin layers to increase the integration density. These thinner layers cause warping-type deformations during processing. In this study, warping during the development of a stacking composed of a silicon substrate coated with two thin layers, one dielectric in undoped silicate glass (USG) and the other metallic in platinum, was numerically analyzed and validated by comparison with experimental measurements. The numerical study presented in this paper has several components that make it simple and reliable. Indeed, simplifications of the loading conditions were introduced and validated by comparison with experimental results. Another part of the simplification is to integrate a homogenization approach to reduce the number of calculations. The efficiency and precision of the homogenization approach were validated for the mechanical and thermomechanical models by comparing the heterogeneous and homogenized models. Full article

The fact that the use of a large number of plastic products has brought serious pollution to the environment has always been the focus of global attention. The development of photocatalytic degradable plastics is one of the effective ways to solve the problem of “white pollution”. In this work, La³⁺ modified TiO₂ nanoparticles were prepared by ball milling and characterized. La³⁺/TiO₂ was mixed with Polyvinyl chloride (PVC) plastic to make a photodegradable composite film, and the photodegradation performance and mechanical properties of films were evaluated. The photodegradable films were characterized by infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), and scanning electron microscopy (SEM). After 30 h UV irradiation, the weight loss rate of the PVC was only 2.12%, while that of the TiO₂/PVC reached 8.94%. The accelerating of the degradation rate was due to the mixing of TiO₂ into PVC. As for the La³⁺/TiO₂/PVC composite film, when the mass percentage of La³⁺/TiO₂ was 1.5%, the weight loss rate of La³⁺/TiO₂/PVC sample reached a maximum of 17.78%, which was eight times the degradation rate of PVC and two times the degradation rate of TiO₂/PVC. The La³⁺/TiO₂/PVC film showed good photodegradability. La is a transition metal element with a special 4f electronic structure. The reaction mechanism of photodegradation of PVC by the interaction of La³⁺ and TiO₂ were discussed. Full article

In this work, an improved methodology of cross-sectional scanning electron microscopy (SEM) analysis of thin-film Ti/V/Ti multilayers was described. Multilayers with various thicknesses of the vanadium middle layer were prepared by magnetron sputtering. The differences in cross sections made by standard fracture, focused ion beam (FIB)/Ga, and plasma focused ion beam (PFIB)/Xe have been compared. For microscopic characterization, the Helios NanoLab 600i microscope and the Helios G4 CXe with the Quanta XFlash 630 energy dispersive spectroscopy detector from Bruker were used. The innovative multi-threaded approach to the SEM preparation itself, which allows us to retain information about the actual microstructure and ensure high material contrast even for elements with similar atomic numbers was proposed. The fracture technique was the most noninvasive for microstructure, whereas FIB/PFIB results in better material contrast (even than EDS). There were only subtle differences in cross sections made by FIB-Ga and PFIB-Xe, but the decrease in local amorphization or slightly better contrast was in favor of Xe plasma. It was found that reliable information about the properties of modern nanomaterials, especially multilayers, can be obtained by analyzing a two-part SEM image, where the first one is a fracture, while the second is a PFIB cross section. Full article