1070-4272/05/7804-0588 C 2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 4, 2005, pp. 588!591. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 4, 2005,
Original Russian Text Copyright + 2005 by Shul’pekov, Lyamina, Rybakov, Kirdyashkin, Maksimov.
AND CORROSION PROTECTION OF METALS
Structure and Properties of a Compound Based on
a Copper Powder and Polysiloxane
A. M. Shul’pekov, G. V. Lyamina, A. N. Rybakov,
A. I. Kirdyashkin, and Yu. M. Maksimov
Department of Structural Macrokinetics, Tomsk Scientific Center, Siberian Division, Russian
Academy of Sciences, Tomsk, Russia
Tomsk State University, Tomsk, Russia
Received November 29, 2004
Abstract-The phase composition, thermal stability, and electrical conductivity of a compound formed
by a polymethylsiloxane lacquer and copper were studied in relation to the temperature of formation of
a coating on its basis.
At present, development of heating elements with
a large heating surface area and high efficiency is
a topical task. The most effective solution to this prob-
lem is deposition of an electrically conducting coating
onto the surface of an article to be heated. A coating
of this kind can be created in the simplest way by
depositing a suspension based on an electrically con-
ducting powder and a polymer binder by the paint-
and-varnish technology. The electrical conductivity of
such composite coatings (compounds) is provided by
the contact between particles of the conducting phase
. Apparently, the electrical conductivity of a com-
pound is affected both by the nature of particles and
the phase composition of their surface and by the prop-
erties of the polymeric matrix.
As an electrically conducting phase was used pow-
dered copper of the PM 1 brand. It is known that
a considerable oxidation of copper starts at 1803
200oC, depending on the dispersity of the metal.
However, it may be assumed, based on the data of ,
that incorporation of the metal into the polymeric
matrix should prevent its oxidation.
Compounds based on most of organic polymers
have a low working temperature (not higher than
150oC) because of the destruction of macromolecules.
It has been suggested to use as a binder for the elec-
trically conducting compound an organosilicon poly-
mer stable against oxidation up to 400oC .
The present study is concerned with properties
(electrical conductivity, thermal resistance, phase com-
position) of the system constituted by a polysiloxane
lacquer and copper.
The compound was prepared by mixing a toluene
solution of the polymer (15 wt %) with powdered cop-
per in a 2 : 1 ratio (by weight). The mixture was
ground in a porcelain mortar and applied on glass
plates, the resulting coatings were dried at 503350oC
for 1 h. The thermal destruction of the compound was
studied by differential thermal analysis (DTA) on
a Q-1500 instrument.
The phase composition of the metal in the com-
pound was determined by X-ray phase analysis
radiation) and voltammetric
(VA) analysis with a carbon paste (CP) electrode in
the cyclic voltammetry (CVA) mode .
The coating surface was analyzed by a nondestruc-
tive VA method with an all-in-one sampling and in-
dicator electrode (Hg and HgNa) . The voltam-
mograms were recorded in the differential mode of
potential variation on a PU-1 polarograph. The phase
composition of the surface and bulk of the compound
was studied using two methods of solid-phase voltam-
metry (see table).
The electrical conductivity of a coating largely de-
pends on the particle packing density and the unifor-
mity of distribution of Cu particles in the bulk.
Mechanical grinding of a Cu powder in a solvent,