Rusian Science News

Source: www.informnauka.ru/eng

SURFACTANT SPECIES AGAINST ICING

01/15/2009

Surface icing problems are acute in Russia. Researchers suggest that
aluminium constructions should be protected from ice formation via covering
them by silicon dioxide and surfactant species.

Further information: Irina Kireenko, chief production engineer, laboratory
of physicochemical methods for investigation of gaseous medium, A.V.
Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy
of Sciences, Novosibirsk; irina@che.nsk.su 

To avoid icing, the surface should be protected from wetting. Specialists
of the laboratory of physicochemical methods for investigation of gaseous
medium at the A.V. Nikolaev Institute of Inorganic Chemistry (Siberian
Branch, Russian Academy of Sciences) suggest that solid surfaces should be
processed by cationic surfactant species (CSFS), which possess the minimal
cohesion with ice. The advantage of such covering is that it is durable,
easily restored, its maintenance does not require additional power.

One of the primary properties of surfactant species is their ability to be
adsorbed at the interfaces, to change properties of the surface they settle
upon. Surfactant species are applied in many manufacturing processes where
it is necessary to regulate wetting, specifically, for attributing
hydrophobic (water-repellent) properties to the surface. Prevention of
electric insulator contamination, roofing manufacturing technologies,
profiles for producing printed boards, the heat-exchange surface of
air-cooler in refrigerating plants, covering for machinery, which are not
subject to icing – this is an incomplete list of problems, resolution of
which requires establishment of hydrophobic covering. 

In the course of the experiment, solid bodies were aluminium and silicon
oxides, aqueous solutions of cetyltrimethylammonium bromide and
tetradecylammonium bromide - CSFS.  The both substances are well adsorbed
on solid surfaces and attribute hydrophoby to them. In case of higher
concentrations of solutions, surfactant species lie down on the surface as
a second layer, and it becomes hydrophilic again. It is complicated to wash
them off by water, and it is unlikely that they can be removed completely.

The results testify that the CSFS adsoption on the silicon oхide
is stronger, its indicators are much higher than those on aluminium oxide.
Apparently, it depends not only on substance structure peculiarities, but
also on the structure and charge of the surfaces they lie upon. 

To protect aluminium components from icing, the authors suggest that they
should be first covered by silicon oхide, to which CSFS stick
better, and then by surfactant species in the required concentration.
Aluminium can be processed by silicon oхide via the microplasmous
oxidation method, which allows to apply covering evenly upon components of
any configuration. Microplasmous coverings consist of polycrystalline
high-temperature oxides that form cellular gradient structure. These thin
coverings (less than 10 microns) possess high porosity (60-70%), surfactant
species are reliably adsorbed in the pores, which attribute water-repellent
properties to the surface. Preliminary investigations of a plate with a 
microplasmous covering have proved that it changes properties irreversibly
after being processed by CSFS. 

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