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Abstract:
A systematic investigation was made on the corrosion behavior of
MCPT-4 ceramets in high-temperature molten salts. A criterion is thus
developed for the preparation and application of such ceramets’
protection tubes to thermocouples. Ceramets of ternary system MCPT-4 or
of quarternary system in which other component is added are proved
extraordinarily beneficial to the resistance to BaCl2 molten
salt with a continuous service life not less than 1400h. Their corrosion
losses are mainly due to the electrochemical corrosion to metallic
molybdenum at a corrosion rate increasing with Mo content. Therefore,
the molybdenum content in ceramet should be decreased as possible to
provide it with enough resistance to corrosion, subject to satisfaction
of the resistance to thermal shock given to ceramet protection tube.
After sintered in H2 atmosphere at 1800℃, a part of Cr2O3
in MCPT-4 ceramets will be reduced to metallic chromium and then forming
solid solution together with molybdenum. The additive Cr2O3
in Mo-Al2O3 system will serve the function
of bridge or tie to strengthen the combination of metallic phase with
ceramic phase, thus improving the properties of ceramets.
Key words:
Ceramet
Molten salt Corrosion
Received
19910521, received in revised form 19920620
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