REDUCTION OF DEUTERIUM PERMEATION THROUGH DIN-1.4914 STAINLESS-STEEL (MANET) BY PLASMA-SPRAY DEPOSITED ALUMINUM

The paper describes the formation of a permeation barrier on DIN 1.491 4 (MANET) martensitic stainless steel by plasma spraying aluminium on the surface of the steel, followed by heat treatment of the sample to form Al3Fe and Al5Fe2. Vacuum plasma spraying was chosen because it en sures that the sample will be exposed to low temperatures during the A l layer deposition and will not interfere with the heat treatment that MANET has to undergo in order to produce a homogeneous, fully martens itic structure. Measurements of the permeation rate of deuterium in th e bare and aluminium-deposited MANET were performed by a gas permeatio n technique over the temperature range 573-743 K and for driving deute rium pressures in the range 3-50 kPa. Such measurements showed a reduc tion of the permeation rate between two and three orders of magnitude and there was evidence that surface reactions were the rate governing process.