RESUMO
In order to improve the waterproof and mildew resistance of electronic equipment, a superhydrophobic coating was prepared on a circuit board. First, hexadecyl trimethoxysilane was used to modify the nano silica and nano zinc oxide particles, and then the modified nanoparticles were mixed with the silica sol. Then the superhydrophobic coating was prepared on the surface of the printed circuit board by a spraying process. The preparation technology and physical and chemical properties of the coating were studied. The contact angle of the final sample can reach 169.47°, the sliding angle can reach 1.2°, it has good acid and alkali corrosion resistance, resistance to NaCl, self-cleaning performance and antimildew performance.
RESUMO
The effects of the extrusion process and CaO addition amount on microstructure, mechanical, and corrosion properties of AZ31 alloys were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), standard tensile testing, and so on. The grain size of AZ31 or AZ31-1%CaO alloy becomes larger with increasing extrusion temperature. The grain size of AZ31-1%CaO alloy is much smaller than that of AZ31 alloy at the same extrusion temperature. In addition, the formation of the Al2Ca phase caused by CaO addition refines the grain size, and the recrystallization of AZ31-1%CaO alloy is improved significantly. The recrystallization grains distribute more uniformly as the increase of extrusion ratio, and the completely recrystallized grains distribute uniformly in the form of equiaxed crystals with an extrusion ratio of 9. Tensile testing results show that extruded AZ31-1%CaO alloy at the extrusion temperature of 300 °C and an extrusion ratio of 9 exhibits the best mechanical properties. While corrosion properties of AZ31 alloys decreases due to the addition of CaO.
