Nickel based alloys to prevent metal dusting degradation

Abstract

An article of manufacture for reducing susceptibility of a metal pipe to metal dusting degradation. The article includes a multi-layer tubing having an alloy layer and a copper layer. The alloy layer can include a Ni based, an Al based and an Fe based alloy layer. In addition, layers of chrome oxide, spinel and aluminum oxide can be used.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS [0001] This application claims the benefit under 35 USC 119(e) of U.S. Application 60 / 686,480, filed Jun. 1, 2005, incorporated herein by reference in its entirety.GOVERNMENT INTEREST [0002] The United States Government has certain rights in the invention pursuant to Contract No. W-31-109-ENG-38 between the U.S. Department of Energy and the University of Chicago operating Argonne National Laboratory.BACKGROUND OF THE INVENTION [0003] This invention relates to a method of manufacture and alloy composition for preventing metal dusting degradation. More particularly the invention relates to nickel-based alloys with aluminum addition and also to the use of a copper-based layer to prevent metal dusting-corrosion. [0004] Metal dusting is a catastrophic corrosion phenomenon that leads to the deterioration of structural metals and alloys into a dust composed of fine particles of the metal / alloy and carbon. This is usually a localized form of at...

AI Technical Summary

Benefits of technology

The patent text describes a method to prevent metal dusting, which is caused by the crystallization of carbon inside metal alloys. The invention proposes the use of bimetallic tubing with a dense copper layer to stop the formation / deposit of carbon and the diffusion of carbon, thereby preventing metal dusting corrosion. The text also describes the development of several Ni-base alloys that have superior resistance to metal dusting degradation when exposed to highly carbonaceous gaseous environments. These alloys have good mechanical strength properties and can be used as monolithic structural materials in chemical, petrochemical, and syngas plants at temperatures up to 900° C. The composition ranges of the alloys are controlled to improve mechanical strength properties and resist metal dusting.

Problems solved by technology

However, carbon atoms still can diffuse through the defects in oxide scale and reduce the Fe-containing spinel phase to form channels for carbon diffusion.

Whenever the channels form, there is no way to stop the diffusion of carbon into alloys.

This process leads to initiation and propagation of pitting corrosion.

However, the mechanical strength of copper at high temperature is too low.

It is thus difficult to directly use pure copper as a structural material at elevated temperatures.

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