Latest ArticlesThe surface of hydromagnesite particles were modified by a wet-modification method. The influences of type and dosage of surface modifier, slurry concentration, modification temperature and time on the contact angle and activation index of hydromagnesite particles were investigated. The modified hydromagnesite particles were characterized by contact angle measurement, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. The results show that a suitable modifier is sodium stearate and the optimum condition is slurry concentration of 50 g/L, modifier dosage of 4% (in mass fraction) of modified hydromagnesite particles, modification temperature of 75 ℃ and time of 50 min. Under the optimum condition, the contact angle of modified product is 130.9° and the activation index is 99.97%. There is little influence of surface modification on the phase composite, chemical structure, thermal decomposition and morphology of hydromagnesite particles. The essence of the modification of hydromagnesite particles is that the hydrophilic group of sodium stearate is absorbed on the particle surface due to the physical adsorption and the hydrophobic group faces outward. Therefore, the surface of hydromagnesite particles changes from hydrophilic to hydrophobic.
Perfluorodecyltrimethoxysilane (PFDMS) and tetraethyl orthosilicate (TEOS) were hydrolyzed in acid solutions and subsequent copolymerization with ammonia to perform in-situ fluorination of silica (SiO2) nanoparticles. A superamphiphobic coating with a good wear resistance was prepared via stacking the fluorinated SiO2 nanoparticles with a double-sided adhesive tape on a glass substrate. It is indicated that the effective introduction of C-F on SiO2 surface through in-situ fluorination could lower the surface energy. The contact angles of water, edible oil and hexadecane are 165°, 155° and 151°, respectively. After 50-cycle friction test with a sandpaper, the water contact angle still exceeds 155°. However, the oil contact angle drops to 132°. It is a simple and environmentally friendly preparation method.
In order to analyze the material removal mechanism in the precision machining process of the cleavable brittle gallium oxide crystal, a diamond indenter was used in a model G200 nanoindenter to determine the nanomechanical properties of two main crystal faces (100) and (010) of β-Ga2O3, respectively. Based on the nanoindentation test, the crystal faces both have a "pop-in" phenomenon. The first pop-in loads are 4.31 mN and 5.42 mN, respectively. Based on the variable load nanoscratch test and atomic force microscopy, the crystal faces both have a "pile-up" phenomenon, and the plastic domain processing features appear in the middle of the scratching process. The scratching depths of the crystal faces are 96.5-576.8 nm and 84.6-421.6 nm, respectively
To investigate the growth of high anisotropic planar dendrites, the growth process and the shape of silicon planar dendrites considering both dynamic anisotropy and interfacial energy anisotropy were simulated by a lattice Boltzmann method coupled based on a cellular automata (LBM-CA) model. The related dynamic anisotropic equation was proposed and verified. The effects of interfacial energy anisotropy, dynamic anisotropy and undercooling on the growth of planar dendrites were analyzed. The results show that the planar dendrites exhibit more intense anisotropy than non-planar dendrites, the anisotropy of planar dendrites increases with the increase of interfacial energy anisotropy coefficient, and the anisotropy of planar dendrites increases significantly with the growth rate and partial orientation loss. The planar dendrites grow, and the anisotropy and orientation loss increase with the increase of undercooling. The growth rate, length and number of secondary dendrite arms increase with the increase of kinetic anisotropy.
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