Abstract
Corrosion behavior of various cast alloys has been studied in a high temperature air heater environment for a waste gasification and ash melting system. This air heater was placed in a severe corrosion condition; the temperatures of both the exhaust gas and the heat exchanger tube surface exceed 1000°C. As heat exchanger tube materials, ceramics and metals may be applicable, cast alloys are preferable due to economical reason. However, the corrosion behavior is not completely known. The cast alloys have been exposed to such environment of a demonstration plant in order to examine the corrosion behavior.
The test results suggested the presence of a corrosion peak likely in the temperature range from 800 to 1000°C, and internal corrosion was also found in all the cast alloys. The materials with small carbon content particularly showed from extreme intergranular corrosion. 33Cr-50Ni-15W alloy showed the best corrsion resistance among the alloys.
