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Title: Pack cementation diffusion coatings for iron-base alloys

Abstract

With the aid of computer-assisted calculations of the equilibrium vapor pressures in halide-activated cementation packs, processing conditions have been identified and experimentally verified for the codeposition of two or more alloying elements in a diffusion coating on a variety of steels. The Cr-Si ferrite layers have proven to be very resistant to high temperature cyclic oxidation and to pitting in aqueous solutions. The process has been patented, and is being transferred for industrial application, e.g. for water walls of utility boilers, etc. In the proposed extension of this project, the use of mixed pure metal powders in the pack will be extended to achieve similar ferrite Fe-Cr-Al coatings with excellent oxidation resistance, with the eventual transfer of the technology to industry. In other recent studies, Ni-base alloy rods were aluminized by the halide-activated pack cementation process to bring their average composition to that for the ORNL-developed Ni{sub 3}Al, for use as a welding rod. A similar effort to develop a welding rod for the ORNL Fe{sub 3}Al alloy did not yield reproducible coating compositions or growth kinetics. The continued effort to produce Duriron-type (Fe-18Si-5Cr) coatings on steels was not successful. Literature for the intrinsic diffusion coefficients suggests that this taskmore » cannot be achieved.« less

Authors:
 [1]
  1. Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
83864
Report Number(s):
ORNL/SUB-87-SB154/03
ON: DE95013450; TRN: 95:005352
DOE Contract Number:  
AC05-84OR21400
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Feb 1995
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 20 FOSSIL-FUELED POWER PLANTS; IRON BASE ALLOYS; DIFFUSION COATING; CHROMIUM ALLOYS; DEPOSITION; SILICON ALLOYS; CORROSION RESISTANCE; VACANCIES; BOILERS; SERVICE LIFE; SULFIDATION

Citation Formats

Rapp, R A. Pack cementation diffusion coatings for iron-base alloys. United States: N. p., 1995. Web. doi:10.2172/83864.
Rapp, R A. Pack cementation diffusion coatings for iron-base alloys. United States. https://doi.org/10.2172/83864
Rapp, R A. 1995. "Pack cementation diffusion coatings for iron-base alloys". United States. https://doi.org/10.2172/83864. https://www.osti.gov/servlets/purl/83864.
@article{osti_83864,
title = {Pack cementation diffusion coatings for iron-base alloys},
author = {Rapp, R A},
abstractNote = {With the aid of computer-assisted calculations of the equilibrium vapor pressures in halide-activated cementation packs, processing conditions have been identified and experimentally verified for the codeposition of two or more alloying elements in a diffusion coating on a variety of steels. The Cr-Si ferrite layers have proven to be very resistant to high temperature cyclic oxidation and to pitting in aqueous solutions. The process has been patented, and is being transferred for industrial application, e.g. for water walls of utility boilers, etc. In the proposed extension of this project, the use of mixed pure metal powders in the pack will be extended to achieve similar ferrite Fe-Cr-Al coatings with excellent oxidation resistance, with the eventual transfer of the technology to industry. In other recent studies, Ni-base alloy rods were aluminized by the halide-activated pack cementation process to bring their average composition to that for the ORNL-developed Ni{sub 3}Al, for use as a welding rod. A similar effort to develop a welding rod for the ORNL Fe{sub 3}Al alloy did not yield reproducible coating compositions or growth kinetics. The continued effort to produce Duriron-type (Fe-18Si-5Cr) coatings on steels was not successful. Literature for the intrinsic diffusion coefficients suggests that this task cannot be achieved.},
doi = {10.2172/83864},
url = {https://www.osti.gov/biblio/83864}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 1995},
month = {Wed Feb 01 00:00:00 EST 1995}
}