抄録
The effects of alloying elements, especially of silicon, on the attack of steels by vanadium pentoxide were studied by the attack tests of Cr steel, Ni-Cr steels, Cr-Si steel and Fe-Si alloys. Weight changes of specimens were measured with the following results:
(1) There were little differences in the resistance against the attack between 12%Cr steel and Cr-Ni steels over the temperature range of 750°∼820°C. But above 850°C, 12%Cr steel was attacked heavier than Cr-Ni steels. These results were disscussed with binary phase diagrams of the oxides.
(2) 8%Cr-3%Si steel was superior to 12%Cr steel and 17%Cr-13%Ni steel in the resistance against the attack. Fe-Si alloys were more resistant as the silicon content increased. Therefore, it can be concluded that silicon has a favourable effect on the resistance against the attack.
The siliconizing method of steel with SiCl4 was investigated in H2 atmosphere, and the method to obtain a poreless and silicon-rich surface was established for 12%Cr steel. The resistance of 12%Cr steel against the attack can be increased by siliconizing.
