DECHEMA

About: DECHEMA is a nonprofit organization based out in Frankfurt am Main, Germany. It is known for research contribution in the topics: Corrosion & Oxide. The organization has 756 authors who have published 1307 publications receiving 25693 citations.

The corrosion behavior of several heat resistant materials in air + 2% Cl2 at 300 to 800 °C. Part 2 – Nickel base alloys

Abstract: The corrosion behavior of the alloys 59, C-2000 and HR-160 was investigated in dry air and in air with 2% Cl 2 at temperatures of 300 to 800 °C. Up to 500°C Alloy 59 and Alloy C-2000 do not exhibit any significant attack. At 650°C in particular HR-160 is subjected to a marked increase of the corrosion rates. In the latter case the higher amount of C compared to the other two alloys seems to decrease corrosion resistance. At 800°C the resistance of C-2000 is inferior to that of Alloy 59 which is attributed to differences in the microstructure consisting of Cr/Mo precipitates in the Ni-base matrix which are primarily attacked.

Corrosion Resistance at Elevated Temperatures in Highly Aggressive Environments

Abstract: Corrosion resistance in highly aggressive environments is a critical issue in a number of industrial high-temperature applications. In this paper, the partial pressure situation of some particularly harsh, industrial, high-temperature environments is summarized first. In a second step, issues of high-temperature corrosion resistance are discussed for sulfidizing, carburizing (metal dusting), and chloridizing environments. Discussion is based on three approaches: thermodynamic considerations, experimental results, and the development of protective coatings. As will be shown, all three approaches offer the potential for controlling corrosion resistance of components and, thus, avoiding premature failure. Part of the work behind these approaches is still ongoing.

Investigations for the Validation of the Defect Based Scale Failure Diagrams—Part II: Extension of the Concept and Application to Nickel Oxide, Titanium Oxide and Iron Oxide

Abstract: The chemical stability of oxide scales and the oxide growth kinetics are important factors to consider when choosing a material for high temperature application. Low oxide growth rates and good chemical stability are, however, not the only aspects to be taken into account. The mechanical stability of the oxide scale formed can also play a significant role, especially when external loads or fast heating or cooling rates come into play. In this work, experimental data on oxide scale failure and a defect based scale failure model are used to calculate mechanical stability diagrams for titanium oxide and iron oxide. For these diagrams the original η-c-approach is extended by a term characterizing the level of residual strains in the scale. In addition to titanium and iron oxide this extended approach is also applied to former measurement data on nickel oxide. With the stability diagrams developed it is possible to estimate the maximum tolerable strain for the oxide scale as a function of the physical defect situation in the scale. Metallographic inspection and 4-point bending tests are used to derive the mechanical stability parameter η and the parameter er for the residual strain. Once these parameters are known, metallographic inspection alone is sufficient to estimate the remaining tolerable load or strain limit after a certain oxidation period.