Influence of adsorbed gas at liquid/solid interfaces on heterogeneous cavitation

Abstract

The presence of dissolved gas at the solid/liquid interface can play a crucial role in heterogeneous cavitation. Here we focus our attention on the relationship between gas conditions and cavitation nucleation at planar solid surfaces with alternating hydrophobic/hydrophilic properties. Tapping mode atomic force microscopy and optical microscopy were used to monitor the gas adsorption on the patterns before sonication. Scanning electron microscopy revealed the effects of collapsing cavitation bubbles on the irradiated surfaces. High intensity ultrasonic irradiation (20 kHz) induces the formation of an interfacial gas layer at the solid surface immersed in different liquid media (water saturated with different gases, such as argon, nitrogen or carbon dioxide) by accelerating the adsorption of dissolved gas. Subsequently, the gas rearranges in diverse nano-or microstructures which take further part in the cavitation process. A solvent-exchange method was also applied to induce the formation of artificial gaseous domains accumulated at the solid surface in order to facilitate the cavitation process. By varying the gas adsorption time it is possible to accelerate or to slow down heterogeneous cavitation.The experimental findings on heterogeneous cavitation are discussed in terms of interfacial bubble nucleation and bubble attraction and growth on patterned solid surfaces in liquid media.

Effects of wettability and interfacial nanobubbles on flow through structured nanochannels: an investigation of molecular dynamics

“…The effective interfacial slip influenced by effects associating surface morphology such as wettability, solid atomic arrangement, surface roughness and interfacial nanobubbles (INBs) is still under intense investigation [19]. INBs, the gaseous domains formed at a solid-liquid interface, have been shown to exist on hydrophobic as well as hydrophilic substrates [20]. Using atomic force microscopy, Yang et al [21] demonstrated a strong correlation between surface roughness and the concentration of nanobubbles.…”

“…The aforementioned results demonstrate that effective slip length is strongly influenced by several coupled factors, such as surface roughness, wettability, and the presence of nanobubbles. In addition, properties intrinsic to solids and fluids, such as the atomic arrangement of solids, as well as parameters related to wall-fluid interaction must be taken into account [20]. This study employed molecular dynamics (MD) simulation in a series of investigations aimed at determining the means by which boundary behaviour is influenced by wettability and the presence of INB.…”

Detection of journal bearing vapour cavitation using vibration and acoustic emission techniques with the aid of oil film photography

“…Lubricant contains dissolved gases which accounts for about 10 percent of its volume [1]. The drop in local pressure below saturation pressure, results in release of these dissolved gases from 2 oil, which is termed as gaseous cavitation.…”

Formation of surface nanodroplets under controlled flow conditions

“…The current techniques include trapping by microcavities, emulsion direct adsorption, microprinting, and others (6). The solvent exchange process is a simple and generic approach for producing droplets or bubbles at solid-liquid interfaces that are only several tens to hundreds of nanometers in height, or a few femtoliters in volume (7)(8)(9)(10)(11). The approach has attractive advantages, such as its capability of producing a large number of nanodroplets in one simple step, and its generality in chemical composition of the droplet liquid, and flexibility in aspect ratio of the droplets and spatial structure or size of the substrate (9,12).…”