High Temperature Oxidation and Electrochemical Studies Related to Hot Corrosion
Abstract
In order to aid in further understanding hot corrosion processes, investigations of the electrical behavior of molten Na2SO4 (Sodium Sulfate) have been undertaken. Wagner-Hebb type polarization experiments and total electrical conductivity measurements by an A.C. impedance technique were carried out on melts of Na2SO4. It was observed that the total electrical conductivity of pure Na2SO4 was of the order of 2.33 x .1 (ohm-cm)(-1) and varied only slightly with changes in the activity of Na2O. From the Wagner-Hebb type D.C. polarization experiments on pure Na2SO4, the electron conductivity was shown to be much greater than the electron hole conductivity over the entire range of Na2O activities. The partial conductivity of electrons in Na2SO4 was about two orders of magnitude less than the total electrical conductivity. Additionally, studies were conducted to examine the nature of vanadium hot corrosion on two ceramic coatings (alumina and zirconia). Experiments showed significant solubility of V2O5 in Al2O3 while apparently causing little surface corrosion of the alumina. Similar work with stabilized zirconia samples evidenced definite corrosive dissolution of the surface. Electrical conductivities of a variety of partially- densified stabilized zirconia samples were measured to determine the effect of porosity on electrical transport. Thermodynamic models of both the Al2O3-Na2SO4- V2O5 and the stabilized zirconia-Na2SO4-V2O5 systems were described and compared to experimental data. (kt)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1989
- Accession Number
- ADA219558
Entities
People
- D.-h. Kim
- G. Simkovich
- R. Reidy
Organizations
- Pennsylvania State University