Yeeli Kelvii Kwok

By Yeeli Kelvii Kwok

One-dimensional (1D) nanostructures are generally used to describe large aspect ratio rods, wires, belts, and tubes. The 1D ZnO nanostructures have become the focus of research owing to its unique physical and technological significance in fabricating nanoscale devices. When the radial dimension of the 1D ZnO nanostructures decreases to some lengths (e.g., the light wavelength, the mean of the free path of the phonon, Bohr radius, etc.), the effect of the quantum mechanics is definitely crucial. With the large surface-to-volume ratio and the confinement of two dimensions, 1D ZnO nanostructures possess the captivating electronic, magnetic, and optical properties. Furthermore, 1D ZnO nanostructure’s large aspect ratio, an ideal candidate for the energy transport material, can conduct the quantum particles (photons, phonons, electrons) to improve the relevant technique applications. To date, many methods have been developed to synthesize 1D ZnO nanostructures. Therefore, methodologies for achieving 1D ZnO nanostructures are expressed, and the relevant potential application for solar cells are also present to highlight the attractive property of 1D ZnO nanostructures.

Part of the book: Renewable and Sustainable Composites

By Kelvii Wei Guo

The surface of mold steel was processed by the simple Al2O3 surface processing, and the influence of processing time on the surface morphology was studied by 3D profilometer and scanning electron microscopy (SEM). Moreover, the wettability of the Al2O3 microtextured surfaces of mold steel was also investigated. The results show that the surface morphology of mold steel varies with Al2O3 processing time. It reveals that the initial surface without any Al2O3 processing treatment behaves as a hydrophilic surface. With the increment of Al2O3 processing time, the surface roughness of the processed surface with the microtextures increases correspondingly. At the same time, the wettability of the microtextured surfaces changes from the hydrophilic to the hydrophobic. When Al2O3 processing time reaches 60 min, the contact angle reaches its maximum at which the relevant surface roughness is the minimum. It indicates that mold steel with an Al2O3 microtextured surface can be a potential application in the mold releasement.

Part of the book: Wettability and Interfacial Phenomena

By Kelvii Wei Guo

Pulsed Nd:YAG laser was taken to premicromachine DF2 (AISI-O1) cold work steel. The effect of laser-irradiated parameters on the morphology evolution of the processed surface was investigated by 3D profilometer, atomic force microscope (AFM), scanning electron microscopy (SEM), and optical microscopy (OM). Results show that when DF2 (AISI-O1) specimens were irradiated with various parameters, the morphology of DF2 (AISI-O1) cold work steel was changed correspondingly. Moreover, it demonstrates that for a given laser, various kinds of morphology of a laser-machined surface could be established successfully to satisfy with the desired finish surface for the practical applications later.

Part of the book: Engineering Steels and High Entropy-Alloys

By Yeeli Kelvii Kwok

Wettability has been explored for 100 years since it is described by Young’s equation in 1805. It is all known that hydrophilicity means contact angle (θ), θ < 90°; hydrophobicity means contact angle (θ), θ > 90°. The utilization of both hydrophilic surfaces and hydrophobic surfaces has also been achieved in both academic and practical perspectives. In order to understand the wettability of a droplet distributed on the textured surfaces, the relevant models are reviewed along with understanding the formation of contact angle and how it is affected by the roughness of the textured surface aiming to obtain the required surface without considering whether the original material is hydrophilic or hydrophobic.

Part of the book: 21st Century Surface Science