FABRICATION OF LARGE-SIZED COMPLEX-SHAPED COMPONENTS
FROM QUARTZ CERAMICS: RESEARCH AND PRACTICAL ASPECTS.
PART 1. STATISTICAL ANALYSIS OF THE STABILITY
OF THE TECHNOLOGICAL PROCESS
A. G. Romashin,
E. I. Suzdal’tsev,
and M. Yu. Rusin
Translated from Novye Ogneupory, No. 9, pp. 34 – 40, September, 2004.
Original article submitted June 22, 2004.
Results of a statistical analysis of the production process of large-sized components from quartz ceramics are
presented. The technologies examined are characterized by a long-term stability which makes it possible to re
liably control the production process and reach the required level of physicomechanical properties.
Progress in advanced sectors of industry, specifically
space technology and aircraft engineering, implies the use of
materials with superior performance characteristics. Many
structural elements for supersonic aircraft are fabricated
from refractory, erosion and heat-resistant materials . The
typical elements are the leading edges, nose cone (Fig. 1),
nozzles and nozzle guides of rocket engines, etc. High tem-
perature and aerodynamic pressure are factors that may do
damage (burn-out, surface fusion, vaporization, and ablation
of the material) to aircraft structural elements.
Materials that combine specific properties (such as low
heat conductivity, high thermal stability, mechanical
strength, erosion resistance, ability to transform from the
solid or high-viscosity state to a gaseous state, etc.) are capa
ble of meeting stringent performance requirements placed on
aircraft structures. No materials that display these useful
properties and good fabricability while retaining the original
shape and size have been reported in the literature. At pres
ent, glass-plastics, sitalls, heat-resisting commercial glasses,
and ceramics have found use as heat-protecting structural
materials for aerial fairings [2 – 4]. Good candidates for this
purpose are materials based on quartz glass [5, 6]; in particu
lar, they have a nearly 30-years-long history in the produc
tion of fairings for hypersonic missiles . However, be
cause of the high viscosity and rather high volatility of silica
at temperatures above 2000°C (over 10
Pa × sec), the manu
facture of engineering components, especially of large size
and complex shape, meets with problems . To remedy the
situation, a ceramic technology has been developed which
made it possible to fabricate components of virtually any size
and shape. Here a range of technological factors should be
complied with such as the high purity of raw materials,
molding technique, granular composition of the semi-fin-
ished product, temperature regime, etc.
Our goal in this study was to consider factors of prime
importance for the technology of large-sized (of base diame
ter up to 400 mm and height up to 1200 mm) complex-
shaped fairings made from glass ceramics. Prior to use, the
quartz glass was thoroughly treated for purity , using in
the process a grinding technology (grinding bodies, the lin
ing of the ball mill, water) equally carefully controlled for
cleanliness. Generally, a quartz ceramic technology for serial
production of fairings should include (i) proper conditioning
of raw materials, grinding bodies, and the lining of the ball
mill; (ii) grinding of the precursor material; (iii) molding of
preforms; (iv) calcination of preforms to meet a set of re
quired properties; (v) machining of the calcined preforms to
required size and geometry; (vi) assembling the ceramic
shell together with a metallic frame.
The molding technique chosen is of key importance for
the manufacturing technology. Of the well-established tech
niques for molding preforms from quartz ceramics (slip cast
ing of aqueous suspension into porous molds; freezing; elec
trophoretic and thermoplastic molding; hot pressing and cen
trifugal casting), slip casting is usually considered the best
for molding large-sized and complex-shaped components us
Refractories and Industrial Ceramics Vol. 45, No. 6, 2004
1083-4877/04/4506-0435 © 2004 Springer Science+Business Media, Inc.
Tekhnologiya Research and Production Enterprise, Obninsk,
Kaluga Region, Russia.