By using nc-Ni coatings as a model system, systematic experiments were designed to evaluate the interaction between the microstructural and mechanical properties tailored by electrodeposition conditions. A direct correlation between grain size and texture was established for the first time. The grain size of the (111) crystalline plane decreases with the texture coefficient (RTC) regardless of the process conditions, and that of the (220) plane has different trends. Then, a peculiar phenomenon is revealed that the dependence of hardness on grain size is accurately described by the Hall-Petch relationship when changing the temperature or pH, but with different slopes, while it deviates from such a relationship with changing current density, denoting more underlying mechanisms related to texture. Finally, a surprising degree of influence of texture on hardness and elastic modulus is also presented, with the overall trend of hardness increasing with texture; and when the RTC of (111) exceeds 40%, the elastic modulus increases with texture, implying a fundamental relationship between modulus and texture. Texture predominates over the other factors on the elastic modulus, revealing the importance of elastic anisotropy. Significantly, the present work suggests a useful tailoring routine to fabricate high quality nc-Ni coatings with the desired structure and mechanical properties.

To understand the evolution of dynamic stiffness of damaged synthetic fiber mooring ropes, experimental investigations of polyester and high modulus polyethylene (HMPE) ropes are systematically performed utilizing a specially designed experimental system. An experimental procedure is proposed and test results show that the dynamic stiffness increases with increasing mean load and loading cycles, while decreases with increasing strain amplitude and damage level. The similarity criterion of dynamic stiffness is derived from the dimensional analysis for damaged ropes and verified by experiments. An empirical expression that accounts for the damage, mean load, strain amplitude, and loading cycles is proposed to describe the damage effect upon dynamic stiffness of synthetic fiber mooring ropes.

A super-hydrophobic aluminum alloy surface with decorated pillar arrays was obtained by hybrid laser ablation and further silanization process. The as-prepared surface showed a high apparent contact angle of 158.2 ± 2.0° and low sliding angle of 3 ± 1°. Surface morphologies and surface chemistry were explored to obtain insights into the generation process of super-hydrophobicity. The main objective of this current work is to investigate the maximum spreading factor of water droplets impacting on the pillar-patterned super-hydrophobic surface based on the energy conservation concept. Although many previous studies have investigated the droplet impacting behavior on flat solid surfaces, the empirical models were proposed based on a few parameters including the Reynolds number (Re), Weber number (We), as well as the Ohnesorge number (Oh). This resulted in limitations for the super-hydrophobic surfaces due to the ignorance of the geometrical parameters of the pillars and viscous energy dissipation for liquid flow within the pillar arrays. In this paper, the maximum spreading factor was deduced from the perspective of energy balance, and the predicted results were in good agreement with our experimental results with a mean error of 4.99% and standard deviation of 0.10.

An Ni/nanodiamond composite coating was deposited on carbon steel in a traditional Watt’s solution without additives via direct current (DC) electroplating. The effects of the nanodiamond concentration and current density in the plating solution on the morphology, grain size, and texture of the Ni/nanodiamond composite coating were observed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The distribution of the nanodiamond particles in the composite coating was investigated by Raman spectra and SEM. The mechanical properties of the composite coating, such as its elastic modulus and hardness, were examined using a Nano Indenter XP nanometer mechanical test system. The coefficient of friction was tested using a Universal Micro-Tribotester. The results demonstrated that the preferential orientation of the Ni/nanodiamond composite coating varied from the (111) crystal orientation of the pure nickel coating to the (200) crystal orientation. When the nanodiamond concentration in the plating solution was 8.0 g/L and the current density was 3.0 A/dm², the hardness of the composite coating reached the maximum value of 5.302 GPa and the friction factor was maintained at around 0.1. The average grain size of the composite coating was reduced to 20.4 nm.

This paper presents a method to simultaneously measure the thickness and refractive index of the thermally grown oxide (TGO) in thermal barrier coating (TBC) by using a reflective terahertz time-domain spectroscopy (THz-TDS) system. First, an optical transmission model of THz radiation in the multilayer structure of TBC is established. Owing to the different structures of TBC before and after forming the TGO layer, two different transmission models are established, respectively. Then, the experimental signals from the samples after different thermal cycles are obtained by the THz-TDS system. By fitting the experimentally measured reflected THz signals from the TBC samples to the proposed optical model using an optimization algorithm, the thickness and refractive index of the TGO are determined. In this work, four samples with different thicknesses of TGO layers are analyzed. The results of thickness of TGO layer are verified by SEM observation, and a reasonable agreement is obtained.

Nanoscale silicon film electrodes in Li-ion battery undergo great deformations leading to electrochemical and mechanical failures during repeated charging-discharging cycles. In-situ experimental characterization of the stress/strain in those electrodes still faces big challenges due to remarkable complexity of stress/strain evolution while it is still hard to predict the association between the electrode cycle life and the measurable mechanical parameters. To quantificationally investigate the evolution of the mechanical parameters, we develop a new full field 3D measurement method combining digital image correlation with laser confocal profilometry and propose a strain criterion of the failure based on semi-quantitative analysis via mean strain gradient (MSG). The experimental protocol and results illustrate that the revolution of MSG correlates positively with battery capacity decay, which may inspire future studies in the field of film electrodes.