Xiangyu Yin

Bioinspired Self-Healing Organic Materials: Chemical Mechanisms and Fabrications

Design and preparation of organic materials having the ability to automatically restore their mechanical and physical properties are of great importance because of the extensive application ranging from aerospace components to microcircuitry, where the accessibility is highly limited and the reparability of materials is lower. The self-healing behavior is actually a dynamic property of material, resembling what is possessed by nature living systems. Therefore, fabrication of most self-healing materials is actually inspired by nature. This tutorial review focuses on the basic chemical mechanisms that have been successfully adopted in designing self-healing organic materials. It specially covers recent development in the design of materials with durable, easy repairable or self-healing superhydrophobic surfaces and coatings.

Influence of potentials on the tribocorrosion behavior of 304SS in artificial seawater

Corrosive wear involves chemical and mechanical mechanisms and the combination of these mechanisms often results in accelerated materials degradation. In this work, pin-on-disk friction experiments were carried out in artificial seawater to investigate the influence of applied potential on the tribocorrosion behavior of 304SS. The obtained results demonstrate that when the applied potential was below the pitting potential of passive film, corrosion and wear interacted to make the total material loss increase obviously; however, when it exceeded this pitting potential, corrosion was inhibited by the rubbing process. Study of the worn surfaces and the cross-sections indicate that depending on varying applied potential, different features of wear tracks were involved, and it was the form of mechanical and corrosion-accelerated delamination wear that determined the total mass loss of 304SS during tribocorrosion.

Tribocorrosion behaviors of 304SS: Effect of solution pH

The tribocorrosion behavior of 304SS in chloride-containing solutions with different pH (pH 7.2–9.2) was investigated under rubbing conditions of 50 N and 100 R min−1 using a pin-on-disc tribometer with an Al2O3 pin mounted on a vertical rotating axis. When combined with rubbing, the corrosion of 304SS was accelerated due to the formation of galvanic couples between the mechanical depassivated areas and the surrounding passivated areas. In addition, the continuous sliding-over processes also make the pitting corrosion to occur more easily due to the affinity of Cl− to metal cations near the active surface. However, OH− has better affinity than Cl−; therefore, a high pH solution mitigates the local corrosion with a wear track. It was found that high pH solution exhibits good lubricity, and both the friction coefficient and total material loss reduce evidently with increasing pH. From the calculation results and wear morphologies, we can confirm that pure mechanical and corrosion-accelerated wear, including abrasion and delamination, are among the chief reasons for material loss.

Controlling liquid movement on a surface with a macro-gradient structure and wetting behavior

A structure controlled gradient surface has been fabricated by a simple method. The gradient divides the surface into areas of water droplet sliding and adhesion. Meanwhile, this gradient surface has the ability of controlling the motion of an oil droplet.

Rabbit hair regenerative superhydrophobicity

A proof-of-concept example of using fibrous rabbit hair absorption/release of low surface energy materials (perfluorooctyl acid, PFA) to achieve rapid and controllable regenerative superhydrophobicity is reported. The superhydrophobicity can be rapidly restored in different ways including heating, evacuation and rubbing.

Highly efficient thermogenesis from Fe3O4 nanoparticles for thermoplastic material repair both in air and underwater

The development of synthetic materials that function well under complicated working conditions is of pivotal importance for many practical applications. In this work, we report a facile and universal method that imparts robust repair of thermoplastic materials in a wide range of working environments. The repair process takes advantage of the highly efficient photothermal effect enabled by monodispersed Fe3O4 nanoparticles incorporated into a number of thermoplastic polymers. We demonstrate that the robust thermogenesis not only allows the polymers to be repaired under the conditions of scratching, rupture and fragmentation in air, but also allows for rapid in situ repair of material defects underwater. This method is versatile, straightforward and opens up a novel practical route for material repair, especially for the repair of underwater coatings and components.

Time Dependence of Tribocorrosion Behavior for Stainless Steel and Alumina Tribocouples in Seawater

ABSTRACT Tribocorrosion is an important phenomenon encountered in many practical engineering situations, resulting in accelerated materials degradation and serious economic losses. In this work, pin-on-disk friction experiments were carried out in seawater to investigate the dependence of tribocorrosion on time. As rubbing proceeded, the mass loss rate of 304SS decreased, and the dominant wear mechanism changed from abrasion to delamination. In addition, during tribocorrosion, friction-induced α′-martensite would be transformed at room temperature. The volume fraction of transformed martensite was determined by test time, which played a dual role in accelerating corrosion and reducing wear. Additionally, the synergistic effect between corrosion and wear was analyzed; the main causes of 304SS degradation during tribocorrosion were pure mechanical wear and corrosion accelerated wear.