RESEARCH AND DEVELOPMENT
STUDY OF MOLDING BILLETS OF MIXED SUSPENSIONS
BASED ON LITHIUM ALUMINOSILICATE AND QUARTZ GLASSES
E. I. Suzdal’tsev,
D. V. Kharitonov,
and A. V. Dmitriev
Translated from Novye Ogneupory, No. 8, pp. 34 – 42, August 2008.
Original article submitted February 4, 2008.
It is shown that one way of synthesizing new composite materials for producing antenna fairings may be the
method of molding billets from mixed suspensions of lithium aluminosilicate and quartz glasses followed by
sintering to the required level of physicotechnical properties. These studies make it possible to isolate a region
content (5 – 40%) within whose limits it is possible to prepare materials with quite high strength, i.e.
from 75 to 120 MPa, and a broad spectrum of dielectric properties: a dielectric permittivity from 5.0 to 6.7,
and a dielectric loss tangent from 0.009 to 0.007. It is established that the most uniform structure occurs for
specimens molded from slips with a moderately fine SiO
addition (5 – 7% content of 63 – 500 mm particles)
that promotes the minimum amount of open porosity in billets.
In order to satisfy the increasing specifications for the
operating characteristics of rocket nose cone antenna fairings
materials should be created combining a set of such charac-
teristics as low thermal conductivity, high heat resistance,
mechanical strength and erosion resistance, and some others.
A decisive factor in choosing material for an actual fair-
ing from the point of view of providing radio engineering
properties is the absolute value of dielectric permittivity and
relatively low dielectric loss tangent. The effect of the value
of material dielectric permittivity on fairing properties is
considered from two positions. On one hand, an increase in
dielectric permittivity may give a very favorable effect, i.e. a
reduction in wall thickness. On the other hand, an increase in
this material property leads to an increase in bearing errors
introduced by the wall of the fairing, and it increases the de
pendence of bearing errors on the frequency of the ultrahigh
frequency (UHF) field. This effect is undesirable since it re
duces the fairing bandwidth-duration product with respect to
bearing error .
Taking account of these specifications among the most
promising materials for manufacturing high-speed rocket an
tenna fairings are quartz ceramic and glass ceramic materials
based on crystallized glass whose dielectric permittivity is
3.3 – 3.5 and 7 – 8 respectively. However, as can be seen
from the values of material dielectric permittivity, they only
provide a value of this parameter in two narrow ranges.
Whereas work is known making it possible to expand the
range of dielectric permittivity of glass ceramic of
b-spodumene composition to 12 [2, 3], the question of pre-
paring material with a dielectric permittivity of 4 – 7 for use
in highly loaded rocket technology objects remains open.
At the basis of creating material with the required dielec-
tric permittivity is the principle of using an addition of an
other material having a significantly lower or higher dielec
tric permittivity. Here the following condition should be ful
filled: during material heat treatment the addition should not
react with the matrix material, only being an extraneous in
clusion uniformly distributed throughout the volume. In ad
dition, as was shown in , the dependence of dielectric
permittivity on material composition is described most pre
cisely by the Lichtenecker equation:
loge = C loge
where e, e
are dielectric permittivity of the composite
material, added material and matrix material respectively; C
is the volume concentration of added material.
This principle has been realized in [2, 3] in synthesizing
b-spodumene composition glass ceramic with e =8–12and
in [5 – 8] as a result of which quartz ceramic was prepared
with e = 3.5 – 7.0. However, in spite of the favorable result
(material prepared with the required level of e), this ceramic
was not free from a marked disadvantage, including the lim
Refractories and Industrial Ceramics Vol. 49, No. 5, 2008
1083-4877/08/4905-0366 © 2008 Springer Science+Business Media, Inc.
FGUP ONPP Tekhnologiya, Obninsk Kaluzh Region, Russia.