Role of sodium chloride in low temperaturs hot corrosion of superalloys.

(1997) Role of sodium chloride in low temperaturs hot corrosion of superalloys. Masters thesis, King Fahd University of Petroleum and Minerals.


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In this thesis, the influence of NaC1 on hot corrosion behaviour of IN 738 and Mar-M 509 at 750°C in static air, under thermal cyclic conditions has been studied. Salt-coating technique was employed, in which alloy samples were coated with approx. 2.5 mg/cm² of salt. Hot corroded sample of IN 738 and Mar-M 509 have been analysed using SEM, point EDS, X-ray mapping, ESCA and XRD techniques and correlated with corrosion kinetics. The results indicated that Na₂SO₄+25%NaCl was very aggressive compared to that of either pure Na₂SO₄+1%NaCl. All samples exhibited enhanced internal sulfidation in the presence of sulfate/chloride salt mixture. It has been concluded that continuous replenishment of Na₂SO₄+25%NaCl mixture on both Ni-base and Co-base alloys resulted in a typical LTHC morphological features during the propagation stage. Basic fluxing model has been proposed for low temperature hot corrosion of IN 738 in Na₂SO₄+25%NaCl mixture during the propagation stage. The initiation and propagation stage of Mar-M 509 is attributed to the attack along W -rich phase and sulfidation/oxidation of Cr. The role of NaCl on hot corrosion behaviour of IN738 and Mar-M 509 has been discussed in the light of the above experimental study.

Item Type: Thesis (Masters)
Subjects: Mechanical
Department: College of Engineering and Physics > Mechanical Engineering
Committee Advisor: Allam, Ibrahim M.
Committee Members: Khan, Zafarullah and Al-Farayedhi, Abdulghani A. and Ahmed, Zaki
Depositing User: Mr. Admin Admin
Date Deposited: 22 Jun 2008 13:54
Last Modified: 01 Nov 2019 13:53