Surface Properties of Ultrasonic Vibration-Assisted ELID Grinding ZTA Ceramics

This study aimed to explore the evolution of surface properties of nanocomposite ceramics during ultrasonic vibration-assisted electrolytic in-process dressing (UVA-ELID) grinding. First, the trajectory of the grain was analyzed, and the motion was simulated using MATLAB to demonstrate the mechanism of UVA-ELID grinding. The critical grinding depth was also calculated under the effect of ultrasonic vibration. Then, the conventional ELID (C-ELID) and UVA-ELID grinding were compared. The surface properties, including surface residual stress, surface microstructure, surface roughness, and surface morphology, were used to evaluate the effectiveness and feasibility of UVA-ELID grinding. Whether it was conventional C-ELID or UVA-ELID grinding, the residual compressive stress was introduced into the machined surface, while the former was lower than the latter. The microstructure of the UVA-ELID grinding was evenly distributed, and the ductility removal occurred during material removal. The surface roughness of Ra and Rz was reduced by 14.5% and 20.6%, respectively, during the UVA-ELID grinding. The surface morphology was dramatically changed with the help of ultrasonic vibration. In a word, for nanocomposite ceramic, the UVA-ELID grinding can significantly improve surface performance and achieve a better machining effect.

Assessment of physical, chemical, and tribochemical properties of biomedical alloys used in explanted modular hip prostheses

During their service life, modular interfaces experience tribological, and corrosion phenomena that lead to deterioration, which in turn can cause a revision procedure to remove the failed prosthesis. To achieve a clearer understanding of the surface performance of those biomedical alloys and the role of the surface properties in the mechanical and chemical performance, samples were taken from retrieval implants made of Ti6Al4V and Co28Cr6Mo alloys. Polarization resistance and pin-on-disk tests were performed on these samples. Physical properties such as contact angle, roughness, microhardness, and Young’s modulus were determined. A correlation between surface energy and evolution of the tribological contact was observed for both biomedical alloys. In tribocorrosion tests, titanium particles seem to remain in the surface, unlike what is observed in CoCr alloys. These metallic or oxidized particles could cause necrosis or adverse tissue reactions.

Recent Progresses in Super-Hydrophobicity and Micro-Texturing for Engineering Applications

Increasing interests have been prevalent lately among the research fraternity for the development of superhydrophobic surfaces considering the favorable properties exuded by them. Recently, anti-microbial superhydrophobic coatings have been employed effectively in anti-biofouling, corrosion resistance, and self-cleaning, anti-reflecting coating, biomedical and cavitation erosion applications. Further, patterned topology by micro/nano surface texturing has been perceived as an engineering opportunity to enhance the surface performance and has opened various avenues for exploration. This work reports the recent research findings pertaining to the concept of superhydrophobicity and micro-texturing particularly in the context of their application for the impediment of corrosion in submerged components. The comprehensive review on superhydrophobic surfaces and micro-texturing suggests that the integrated application of these surface modification techniques for mechanical interlocking of deposited coating.

Effect of Paint Process on the Performance of Modified Poplar Wood Antique

Modified poplar wood is used as the substrate, based on the surface coating process and actual operation requirements of European and American furniture, and the painting process is studied. Four different paint coating methods are applied to modified poplar wood that has undergone different surface pretreatments. The gloss and adhesion of the coating system were measured. The difference in paint film performance of different paint finishes on the modified poplar with different surface pretreatments was discussed. The reasons were analyzed to establish the corresponding relationship between wood surface performance and paint film performance and obtain the best coating process parameters. The number of passes of nitrocellulose (NC) transparent primer was appropriately increasing, and the adhesion of the overall paint film was improved through the bonding between the films after sanding. NC transparent primer has the function of weakening the surface gloss. NC transparent topcoat has the effect of improving gloss. The proper use of PU sealing primer is beneficial to improve the gloss of the paint film, but excessive use will not produce any effect. The paint process of Group C is more suitable for the antique, old-fashioned process of European and American furniture from the perspective of the glossiness of the paint film.

Surface Performance of Chrome-Free Anti-Fingerprint Zinc and Zn-Al-Mg Coated Steel

A principle investigation of the fingerprint resistance, alcohol resistance, solvent resistance, humidity resistance, high temperature resistant yellow degeneration and black tarnish resistance of pure Zinc and Zn-Al-Mg coating were performed in this study. To detect above surface performance and make some constructive suggestions, a series of simulations experiments and a surface performance evaluation system based on light color differentiation measurement instrument were designed. The results show that the two products both can meet the needs of users in above-mentioned surface performance, besides pure Zinc coated product has more advantages in this performance in comparison to Zn-Al-Mg coated product. Users should pay attention to clean the fingerprint regularly which attached to the surface of the steel plate during use and the protection with the exposed surfaces of the steel during shipping.