ISSN 1070-4272, Russian Journal of Applied Chemistry, 2015, Vol. 88, No. 5, pp. 839−845. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © O.Yu. Sorokin, M.L. Vaganova, S.S. Solntsev, I.V. Osin, 2015, published in Zhurnal Prikladnoi Khimii, 2015, Vol. 88, No. 5, pp. 798−804.
AND POLYMERIC MATERIALS
Joining of Silicon Carbide Ceramic
by Hybrid Spark Plasma Sintering
O. Yu. Sorokin, M. L. Vaganova, S. S. Solntsev, and I. V. Osin
All-Russian Scientiﬁ c Research Institute of Aviation Materials, ul. Radio 17, Moscow, 105005 Russia
Received May 20, 2015
Abstract—The possibility of joining of silicon carbide ceramic by hybrid spark plasma sintering (Hybrid SPS/
FAST) was demonstrated. An increase in the brazing temperature and addition of SiC and B powders into the
base braze formulation (С + Si) allowed the seam uniformity to be considerably improved and the thermal cycling
resistance of the brazed structure to be enhanced. Introduction of boron into the braze formulation allows the free
silicon content to be reduced to zero, which is impossible with boron-free brazes.
Ceramic materials based on silicon carbide are
widely used owing to high mechanical properties,
thermal conductivity, and resistance to oxidation, heat,
and radiation. The modern aviation, space engineering,
nuclear power engineering, and electronics demand
increasing amount of articles that should be produced in
the form of complex-shape structures [1–3]. Examples of
some SiC articles are shown in Figs. 1 and 2.
One of the main techniques for fabricating such
structures operating under very severe conditions is
brazing of simpler small-size silicon carbide parts which,
in turn, can be fabricated by different pressing methods
and by inﬁ ltration of a porous C/SiC base with silicon-
containing alloys or silicon-containing compounds
Analysis of published data shows that there are at
least four main routes for obtaining a strong joint of
silicon carbide items with the operating temperature Т >
(1) Use of glasses based on SiO
of CaO, SrO, La
O, MgO, Y
, etc. The main advantages
of such joints are as follows: possibility of obtaining a
gastight joint; stability of thermal properties and strength
at temperatures exceeding 1000°С; possibility of brazing
in an oxidizing medium (in air), which allows the use of
expensive equipment to be avoided.
(2) In-situ SiC formation during the brazing of SiC
items. For example, NASA (the United States) for joining
silicon carbide materials uses uses a procedure known as
ARCJoinT. The joining technology includes the following
steps: (a) coating of the junction area with a carbonaceous
mixture cured at 110–120°С; (b) contact of the junction
area with a melt of silicon or a silicon-based alloy for
the subsequent formation of silicon carbide in the seam;
(c) siliconization at a temperature depending on the
chemical composition of the braze (about 1250–1410°С).
The apparent advantage of this method is the lowest
mismatch of the linear thermal expansion coefﬁ cients of
Fig. 1. Reﬂ ector of Herschel telescope, consisting of 12 silicon
carbide segments brazed with each other (diameter d = 3 m).