Corrosion products of iron, cobalt, nickel, zirconium, chromium, and titanium in V
20
5 melt were examined by metallography, electron probe microanalysis, and X-ray diffraction. The main results obtained are as follows:
(1) Iron. FeVO
4 and FeV
20
6 in addition to wustite, magnetite, and hematite, were found in the corrosion products at 850°C. FeVO
4 and FeV
20
6 were detected in the places which were melt at the test temperature. Magnetite layer formed at 850°C contained vanadium and its composition was considered to be (Fe
1-
xV
x)
3O
4, while magnetite layer at 750°C did not contain vanadium.
(2) Cobalt. A porous and thick scale layer formed at 850°C mainly consisted of Co
3V
2O
8, and a considerably large amount of cobalt was observed in V
20
5 melt.
(3) Nickel. A dense scale layer formed at 900°C mainly consisted of Ni
3V
2O
8, and only a small amount of nickel was detected in V
2O
5 melt. Low oxidation rate of nickel is considered to be due to the formation of the dense Ni
3V
2O
8 layer.
(4) Zirconium. ZrO
2 was formed at 850°C, and the scale was so porous that V
2O
5 melt penetrated into the innner part. The formation of ZrV
2O
7 besides ZrO
2 was observed at 700°C.
(5) Chromium. Solid CrVO
4 was observed in the scale in addition to Cr
2O
3 at 850°C. The former is considered to contribute to the good corrosion resistance of chromium.
(6) Titanium. The formation of TiO
2 (rutile) was observed.
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