Kinetics for Aluminum Coatings and Degradation Properties of Aluminide - Coated and pre-oxidized Haynes230 Alloys via Pack Cementation Route

摘要

Aluminim pack cementation coatings on Haynes 230 alloys have been developed between 500 and 600 degrees C. A single Al3Ni layer was coated on the alloys. The activation energy for growth rate of the coated layer thickness was estimated as 63.1 kJ / mol in the examined temperature range. In order to examine the degradation Wehaviors, the alloys were subjected to high temperature flame via an LPG / O-2 gas torch. In order to test the degradation behaviors, uncoated alloys, coated alloys and oxidized following coated alloys have been prepared. The uncoated Haynes 230 alloys exhibited a weight loss during the torch tests due to the sublimation of chromium oxide on the surface, and the coated allo specimen showed an surface melting due to low melting temperature of the coating layer. However, the coated with oxidation - treated Haynes 230 alloys maintained the original weight due to the presence of an surface in-situalumina layer. The coated microstructures and related coating kinetics are discussed in terms of structural identification and weight changes.