hot corrosion

Question 1

what is two sources of hot corriosn alkali salts

Answer 1

ingestion of sea salt in marine enviroment
combustions of fuels

Question 2

what is known as hot corrosion

Answer 2

DURING COMBUSTION in the gas turbine, sulfur from the
fuel reacts with sodium chloride from ingested air at elevated
temperatures to form sodium sulfate.
➢ The sodium sulfate then deposits on the hot-section components,
such as nozzle guide vanes and rotor blades, resulting in
accelerated oxidation (or sulfidation) attack. This is commonly
referred to as “hot corrosion

Question 3

how to improve the hot corrosion resitance of alloys

Answer 3

➢The effect of Cr is dominant and a minimum of 15wt% is required.
➢Cr has been shown to inhibit “fluxing”
➢Cr decreases the rate of low temperate hot corrosion
➢High aluminium concentrations are desirable in alloys since generally alloys
stay in the initiation stage for longer times as the aluminium concentrations are
increased.
➢Al is detrimental at low operating temperature & 1-4wt%, high Ti levels (or
high Ti : Al ratios) are beneficial.
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