Технические науки / отраслевое машиностроение
Skachcov V.А., Ivanov V.I., Karpenko А.V., Моsejko Yu.V.
Zaporozhe state engineering academy
Composite materials on the
basis of carbon fibers find a wide use in an aerospace technique and aircraft
building as heat-resistant friction elements and heater knots. The technological
methods and properties of carbon-carbon, carbon-aluminum and carbon-magnesium
composite materials are presented in works [1-3]
Carbon-silicon composite
materials on chemical and oxidizing durability substantially differ from the
above-stated materials. Impregnation of carbon composite materials by silicon fusion
supposes the processes of his penetration on transport pores in the volume of
composite, diffusion of silicon atoms through the walls of pores in the
structure of carbon, and also dissolution of carbon atoms for matrix material
in the volume of liquid silicon. During realization of the above-state
processes in the interval of temperatures 1450…1500 °C [4] the reaction carbide
silicon formation is characterized by low speeds, and the degree of
participation of silicon in this process does not exceed 10…15 % from his
volume. At temperatures higher 1600 °C speeds of flowing
for the indicated reaction increases considerably, and a process is completed
by formation of carbides on all volume of contact of atoms for carbon and
silicon. However at the impregnation of carbonized carbon composite materials by
fusion of silicon takes place co-operation of liquid silicon and carbon fibers
that results in the considerable decline of strength and resilient properties
and also shock viscidity of these composite materials.
In this connection there is a
necessity of creation on a surface reinforcing components of composite
materials of fibers of the buffer protective coverage. Such buffer layers must
not co-operate with a carbon and silicon and here to maintain the temperature
of flowing processes without allegations and destruction. The most suitable
materials for the indicated aims are compositions on the basis of quartz.
Carbonized carbon composite materials
exposed to impregnation by fusion of silicon and there is got material with the
closeness of 2,50…2,60 g/sm3, maintenance of carbon 10…12 %, carbide
of silicon 50…55 % and silicon - 33…40 %. Thus did not look dissolution of
reinforcing component - carbon fiber - in molten silicon.
Estimation of possibility for defense
of reinforcing components for carbonized carbon composite materials by
compositions on the basis of quartz with formation of coverage carried out the
method of oxidization in presence oxygen at temperatures to 1000 °С. Durability of the got protective
coverage’s was determined on the size of relative loss of samples mass.
The analysis of the got
results shows that at the increase of temperature for process of oxidization
efficiency of protective coverage’s increases from 20 to 30 %. The increase of
duration of process for components with coverage’s stipulates less speed of mass
loss in relation to components without coverage.
Samples research materials were
made on the basis of carbon fibers with quartz coverage by thick 0.5…2.0 mcm
and their silicification is carry out at the maximal temperature of process
1650 °С [5]. The got composite
material was characterized by the closeness of 2.25…2.35 g/sm3,
maintenance of carbon of 52…58 %, silicon - 25…30 % and carbide of silicon - 22…33
%.
As set by the results of
microstructure analysis, carbon fibers saved the integrity and structure.
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