The preparation and characterization of uniform nanoporous structure on glass

A novel fabrication method of uniform porous structures on the glass surface is proposed. The hydrofluoric acid fog formed by air-jet atomization etches the glass surface to fabricate nanoporous structure (NPS) on glass surface. This NPS shows the enhanced average light transmittance of approximately 92.9% and the superhydrophilic property with a contact angle less than 1° which presents an excellent anti-fog property. Passivated by fluorosilane, the NPS shows nearly the superhydrophobic property with a contact angle of 141.2°. This fabrication method has shown promising application prospects due to its simplicity, low cost and efficiency, which can be easily applied to large-scale industrial production.

Siliceous-sulphate rock coatings at Zhenzhu Spring, Tengchong, China: the integrated product of acid-fog deposition, spring water capillary action, and dissolution

Siliceous-sulphate rock coatings were observed at Zhenzhu Spring, an acid sulphate hot spring in the Tengchong volcanic field, China. These rock coatings are mainly formed of gypsum and amorphous silica. Some alum-(K), voltaite, α-quartz and muscovite were also found. Four different laminae are developed in the rock coatings: gypsum layer, tight siliceous layer, tabular siliceous layer and siliceous debris layer. The gypsum layer is located at the top of the rock coatings, while other siliceous layers appear below the gypsum layer. Geochemical modelling of the fluids was performed to identify the mechanisms responsible for the formation of gypsum and amorphous silica. The results indicated that the occurrence of gypsum is related to the acid-fog deposition and amorphous silica mainly originates from spring water. Fog deposition provided the rock coatings with abundant SO42− and Ca, and the subsequent complete evaporation of the condensed fluids produced gypsum. Seasonal climate change (especially variation in rainfall) determines the fluctuations of capillary action and dissolution. Rainfall events in the wet season led to periods of non-precipitating gypsum and promoted the capillary rise of the spring water. Slightly diluted capillary water (a small amount of rainwater) covered the rock coatings, formed a tight siliceous layer on the rock-coating surface and/or filled the pores among the gypsum crystals forming many tabular siliceous aggregates. Heavy rainfall (high dilution), however, resulted in non-precipitating amorphous silica and accelerated the gypsum dissolution, leaving tabular pores around tabular siliceous aggregates and forming a tabular siliceous layer.

Risk Analysis of Environmental Pollution by Secondary Hydrogen Chloride from Leakage of Phosphorus Trichloride

This study aims to analyse the influence of the pollution of hydrogen chloride which is the side effect of the leakage accident of a 50m3 phosphorus trichloride tank. When the leakage source intensity is 1.06kg/s with the leakage time of 30 minutes, and the distance is about 2700m away from the highest allowable concentration (0.05mg/m3) in air of residential areas, which goes beyond about the distance of 700m over the "Comprehensive emission standard of air pollutants" (GB16297-1996) table 2 (100mg/m3, new sources of pollution emission limits), however, the mean value of hydrogen chloride concentration beyond 400m is less than the that of IDLH (immediately dangerous to life or health concentration), and no half lethal concentration (LC50) appears. The scope and extent of pollution can be significantly reduced by timely using fire water to eliminate smoke to change hydrogen chloride into hydrochloric acid fog and make them drop in a lower position.

Investigation of Corrosion Processing for Ti-6Al-4V in Hydrofluoric-Nitric Acid System

Corrosion processing is an effective way to solve difficult machining of titanium alloy. It can be applied for reducing weight, machining complex shape and fine structure. In this paper, the effects of the bath constituents and operation conditions on corrosion processing rate and surface quality for Ti-6Al-4V were investigated. Corrosion processing rate depends upon hydrofluoric acid concentration, the volume ratio of nitric acid to hydrofluoric acid, temperature. Nitric acid can promote the surface passivation and reduce surface roughness. The surfactant plays a dual role of surface finish improvement and acid fog suppression. During the period of processing, oxide film on the surface is dissolved initially, and there is the faster processing rate. Surface passivation occurs with the extension of time, decreasing processing rate. Finally corrosion processing rate trends to be stable when the growth of passive film and dissolution of the substrate achieve dynamic balance.