HYDROGEN PERMEATION THROUGH IRON, NICKEL, AND HEAT RESISTING ALLOYS AT ELEVATED TEMPERATURES.

Abstract

Materials studied were iron, nickel, 80Ni-20Cr alloy, 50Fe-30Ni-20Cr alloy, HK 40, Incoloy 800, Hastelloy X, and Inconel 600. The hydrogen permeability of nickel was proportional to the square root of the pressure and inversely proportional to the membrane thickness. The activation energy and pre-exponential factor were derived from the temperature coefficient. The hydrogen permeability of nickel was larger than that of iron ( gamma ), and the permeabilities of the heat resisting alloys were between those of nickel and iron ( gamma ). Permeability increased with increase of the nickel content. The formation of the oxide film on the alloy surface in wet hydrogen resulted in a reduction of hydrogen permeability at elevated temperatures.