Yungang Grottoes in Shanxi, China, which represent outstanding example of Chinese outdoor immovable stone artifacts, are precious world cultural heritage. In the present study, the preparation and assessment of superhydrophobic hybrid coatings with photocatalytic activity on the sandstone substrate collected from Yungang were explored preliminarily. The protection efficiency of coating is investigated by measuring the water-stone contact angles, water vapor permeability, water absorption, and resistance to acid and salt corrosion. Results show that the superhydrophobic organic-inorganic hybrid coatings with photocatalytic and self-cleaning properties are highly suitable for the conservation of stone monuments.
This paper presents the short circuit (SC) current interruption capability of a 1.7 kV/72 A silicon carbide (SiC) MOSFET based solid state circuit breaker (SSCB). The interruption process of SSCB is introduced in detail. A test platform is built and the SSCB is tested and discussed at various DC-link voltage, fault inductance and junction temperature. Before the desaturation point (VDS=200 V), SSCB can successfully turn off the SC current. The saturation value of the SC current is positively correlated with di/dt, and the effect of junction temperature (50-150°C) on saturation current is not significant. A SC protection circuit with a response time of 260 ns is proposed and is validated through the test platform.
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