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.

Fast heat treatment methods for al slurry diffusion coatings on alloy 800 prepared in air

Abstract: In the present study aluminum diffusion coatings were prepared on alloy 800H within a few minutes in air using several surface heating methods: induction heating, a natural gas burner, and a heating mat. All such methods are highly relevant for on-site applications, because they are commonly known from post welding heat-treatments. The very short (3 or 5 min) dwell times at temperatures between 700 and 1000 °C were sufficient to produce continuous diffusion coatings with all heat treatment methods. With the heating mat more of the Al-poor (Fe, Cr, Ni)Al phase is formed during diffusion treatment at 1000 °C due to the slower heating and cooling rates in comparison to the other techniques.

Erosion–Oxidation Behavior of Chromized–Aluminized 9% Chromium Steel under Fluidized-Bed Conditions at Elevated Temperature

Abstract: An investigation into the erosion–oxidation behavior of chromized–aluminized 9% chromium steel has been carried out in a fluidized-bed erosion–oxidation rig in air at temperatures of 550 °C to 700 °C for particle impact angles of 30° and 90°, at speeds of 7.0–9.2 m s−1. After exposure for 200 h, the mean-thickness changes were determined, and the specimens were examined and analyzed by scanning electron microscopy and X-ray diffraction.

Thermal deactivation of heterogeneous catalyst, part 1. The theta‐rule ‐ a critical review

Abstract: Thermal deactivation can be described either by deactivation kinetics or by the isokinetic effect. The latter expression is used synonymously with the “compensation effect” and the “Theta-Rule”. An examination of the original literature shows that only the compensation effect is applicable to thermal deactivation but not the Theta-Rule. The introduction of the preparation temperature as a parameter of the compensation effect results in a “modified Theta-Rule”, which describes the experimental data and is proposed for the non-separable kinetics. The consequence of the observed deviations from the validity range of the Theta-Rule is that the activation energy cannot be used as a universal activity criterion.