In Situ Polymerized Self-Healing Microcapsules as Multifunctional Fillers toward Phosphate Ceramic Coatings.

The protective efficacy of chemically bonded phosphate ceramic coatings (CBPC) is notably diminished owing to the presence of micropores and inadequate self-healing capacity in prolonged corrosive environments. Consequently, it is imperative to augment the corrosion and wear resistance of phosphate ceramic coatings while imbuing them with self-healing capabilities. In this work, a novel self-healing phosphate ceramic coating (MC-PTx@CBPC, x = 0.5, 1.0, 1.5) is designed by urea-formaldehyde (UF) in situ polymerization of nanoscale microcapsules encapsulated with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) and evaluated in detail for corrosion and wear resistance. The corrosion inhibition efficiencies of all formulated MC-PTx@CBPC (x = 0.5, 1.0, 1.5) coatings exceed 90%, with the impedance modulus at the lowest frequency (|Z|f=0.01) showing enhancements of 1-2 orders of magnitude compared to pure CBPC. Moreover, the self-healing function becomes active during prolonged immersion. This can be primarily ascribed to the formation of a unique micronanostructure facilitated by nanoscale microcapsules and micrometer-sized alumina ceramics, bonded via the AlPO4 phase. This structure enhances both the hydrophobicity and the bonding strength of the coating. Specifically, following prolonged immersion, the encapsulated PFDTES is liberated from the microcapsules, undergoing hydrolysis and subsequent polymerization upon contact with the electrolyte to form a protective thin film. This film efficiently obstructs the ingress of corrosive agents. Furthermore, the special micronanostructure enhances the hardness of the coating and the releasing PFDTES can form a lubricating film at the interface of abrasion, thus reducing the wear rate and friction coefficient of the MC-PTx@CBPC (x = 0.5, 1.0, 1.5). Therefore, MC-PTx@CBPC (x = 0.5, 1.0, 1.5) possesses excellent corrosion protection, tribological properties, and self-healing capabilities, which provide thought-provoking ideas for phosphate ceramic coatings to protect metals in harsh environments.

Effect of GO content on microstructure and mechanical properties of Ti6Al4V coating reinforced artificial joint.

In this study, we have innovatively proposed a method of in-situ synthesized TiC hard phase to improve the surface mechanical properties of artificial joint materials (Ti6Al4V). In order to explore the optimum graphene oxide (GO) addition, GO/Ti6Al4V composite powders with different proportions (0, 0.5, 1.0, and 1.5 wt.%) were prepared. The homogeneously dispersed GO/Ti6Al4V composite powder was prepared on Ti6Al4V substrate by laser cladding technology. The microstructure, phase composition, and mechanical behavior of GO/Ti6Al4V composite coatings were studied by scanning electron microscope (SEM), optical microscope (OM), energy dispersive spectrometer (EDS), tribometer, hardness tester, and surface profiler. The results showed that the addition of GO could significantly improve the mechanical properties of TC4 substrate. During the preparation of the coating, the grain size of in-situ TiC phase was nanoscale and was distributed between acicular martensite, which played a critical role in enhancing the mechanical properties of the coating. The TiC phase distributed between acicular martensite refine the grain size of α' phase and improve the cutting resistance of the coating. Nevertheless, excessive GO decreased the fluidity of the molten pool, and micro holes tended to generate in the coating, which had a negative impact on the mechanical properties of the coating. At the GO content of 0.5 wt.%, the microhardness of the GO/Ti6Al4V coating was 1.325 times that of pure Ti6Al4V. Under the friction environment of simulated body fluid solution, the average friction coefficient was approximately 0.307 and the wear rate decreased to 3.5 × 10-7 mm3/N · m.

Application of a water jet for cleaning grease and improving the surface adhesion properties of galvanized steel wire ropes.

Traditional cleaning processes may be banned in the near future because of the hazards they pose to the environment. In this study, a water jet was used to clean grease residues from steel wires for the first time. The EDS and SEM results of the steel wire rope surfaces and supplementary water jet impact experiments on galvanized steel plates revealed that when the pressure was lower than 50 MPa and the traverse speed was higher than 600 mm/min, the water jet caused minimal damage to the coating. When the pressure was 5 MPa, the cleaning ratio was between 45 and 60%, and the level of cleaning increased with increasing pressure. Two proposed concepts of exposure ratio and nonexposed area were applied to quantitatively analyze the theoretical upper and lower limits for grease that could be cleaned from two typical structures. The results showed that the lower and upper cleaning limits for structure 7 × 3 were 38.1% and 83.3%, while the lower and upper limits for structure 1 × 3 + 5 × 7 were 35.5% and 59.2%, respectively. This result explains why the grease content of structure 7 × 3 was lower than that of structure 1 × 3 + 5 × 7 after cleaning. In addition, the adhesion test results showed that adhesion to the two kinds of steel wire ropes after cleaning was increased by 126% and 145.71%, respectively, which means that additional processes for improving adhesion could be omitted after using a water jet for cleaning. This is an advantage that traditional cleaning processes do not offer.

Surface modification and biotribological behavior of UHMWPE nanocomposites with GO infiltrated by ultrasonic induction.

In this study, we have innovatively proposed a method for surface modification of ultra-high molecular weight polyethylene (UHMWPE) artificial joint materials with graphene oxide (GO) infiltrated into UHMWPE substrate by ultrasonic induction. The mechanical properties of UHMWPE nanocomposites with GO infiltrated by ultrasonic induction were compared with that of GO mixed. The molecular structure, wettability, peak load, and bio-tribological behavior of GO/UHMWPE nanocomposites were studied using fourier transform infrared spectroscopy, contact angle measuring instrument, electronic universal material testing machine, tribometer, and profilometer, respectively. The results show that the ultrasonic-induction method can make GO adhere to UHMWPE surface well, and GO can significantly improve the wettability of UHMWPE substrate. When the ultrasound-inducted time is up to 12 hr, the wetting angle of the nanocomposites (12 h-GO/UHMWPE) is reduced to 65.24°, which is 20.51% lower than that of the pure UHMWPE. The peak load is 183 N, which is 20.22% higher than that of GO/UHMWPE prepared by the mixing method. The bio-tribological property of UHMWPE nanocomposites with GO infiltrated by ultrasonic induction for 12 hr (12 h-GO/UHMWPE) is the best, and its friction coefficient keeps more stable at a value of 0.0605 under the lubrication of calf serum, which is 11.81% lower than that of UHMWPE mixed with GO by a traditional method, and the wear rate is decreased to 3.25 × 10-5 mm3 N-1 m-1 .

Effect of Laser Rescanning on the Characteristics and Residual Stress of Selective Laser Melted Titanium Ti6Al4V Alloy.

The titanium Ti6Al4V alloy has excellent properties, and is one of the most important and widely used metal materials in the field of modern high-tech. Selective laser melting (SLM) is an ideal process for the rapid prototyping of Ti6Al4V alloy components with complex structures, but the performances need to be further improved. In this paper, the relative density, hardness, and microstructure under different scanning conditions were first analyzed in order to clarify the role of rescanning process in improving the performances. Then, the effects of different scanning strategies on the residual stress were analyzed. The results show that the strategy of partition rescanning has the most significant effect on residual stress. Finally, the SLM experiments of aviation nozzle rings were carried out. The results show that the average residual stress of the Re-SLMed sample was reduced from 322 MPa to 254 MPa.