A MECHANISM FOR PHOSPHATE HARDENING AND PROSPECTS
FOR THE USE OF METAL PHOSPHATE MATERIALS (AN OVERVIEW).
PART II. ADHESIVE PROPERTIES OF BINDING PHOSPHATE MATERIALS
I. A. Karpukhin,
V. S. Vladimirov,
and S. E. Moizis
Translated from Novye Ogneupory, No. 9, pp. 54 – 58, September, 2005.
Original article submitted May 31, 2005.
A mechanism for hardening of phosphate materials and the role of hydrogen bonding in this mechanism has
been considered. The adhesive properties of binding phosphate materials are discussed and factors affecting
the buildup of adhesive bonds between the binding material and the hard surface of a substrate or particles of
the filler are analyzed. Correlations between the properties of the binding phosphate material and the cohesive
forces are considered.
Inorganic binding materials, in particular those of phos-
phate origin, belong to a class of polyfunctional compounds.
Binding phosphate materials for use in the production of
refractories and castables have been studied in much detail
[1, 2]. Despite the wealth of domestic patent literature, the
use of binding phosphate materials for production of corro-
sion-resistant coatings and mortars capable of providing a se-
cure binding of parts and components into a monolithic
structure has not received sufficient attention. In our opinion,
this state of things has a simple explanation — until now, no
reliable theoretical treatment of the very phenomenon of ad
hesion has been proposed. The adhesive interaction between
contacting materials involves a range of physical factors of
different nature, and their contribution to the buildup of ad
hesion bond has never been analyzed and discussed in suffi
cient detail. To date, a few models have been proposed; of
these, the most popular are models of electrostatic and ad
sorptive phase interaction.
An electrostatic model of adhesion proposed by Dery
agin  is based on the concept of a double electric layer
generated at the contact surface of two bodies owing to the
directional adsorption of polar functional groups of an adhe
sive (a binding material after Deryagin’s terminology). Polar
functional groups displaying a large dipole moment are
COOH, –OH, NH
, –CHO, and some others. The Deryagin
theory provides a satisfactory description of the adhesive
properties of organic polymer materials (cellulose, gelatin,
natural rubber) applied from polar solvents onto the surface
of glasses or metals. However, it fails to explain the adhesion
of nonpolar materials, in particular, binding phosphate mate-
rials that are electric conductors to a significant extent (not
dielectrics!) and, for this reason, are not capable of forming a
double electric layer.
The adsorption model is more versatile in this respect; it
considers adhesion as a result of molecular interactions at the
contact boundary. The molecular interactions involve disper
sion forces (up to 30 kJ/mole), induction forces (up to
40 kJ/mole), and hydrogen-bonding (H-bonding) forces
which may vary from 10 to 40 kJ/mole. Not infrequently, the
strong H-bonding with the substrate was effected through
participation of polarized molecules formed because of the
large difference in electronegativity of cationic compounds.
With reference to conclusions drawn in Part I , one can as
sert with certainty that the occurrence of an extended net
work in aqueous H
solutions and the buildup of disor
dered glass-like structures during the hardening of phospho
ric acid species provide good conditions for adhesion of ma
terials based on metal-phosphate bonds. This issue will be
discussed in greater detail later.
Occasionally, concentrated orthophosphoric acid is used
as a phosphate mixing agent; but, viewed technologically,
this technique is not always effective. The common practice
is to use aqueous H
acid solutions or metal phosphate
Refractories and Industrial Ceramics Vol. 46, No. 5, 2005
1083-4877/05/4605-0329 © 2005 Springer Science+Business Media, Inc.
For Part I, see Novye Ogneupory, No. 12, 2004.
MaVR Research and Production Trading Firm, Zhukovskii, Mos
cow Region, Russia.