Formation of diffusion coatings on nickel containing dispersed thoria

Patent · Mon Oct 01 00:00:00 EDT 1973

OSTI ID:4362453

Baldi, A L

Rich chromium diffusion coating on TD nickel or TD Nichrome is obtained in one step by embedding work in chromium diffusion coating pack containing nickel with or without cobalt, and held in an unsealed retort cup at least 15 inches high. Magnesium halide is helpful to have in the pack and pack can also contain metallic iron to reduce coating temperature. Masking is arranged by covering the sites to be masked with a layer of a mixture of nickel powder and inert filler. For benter high-temperature oxidation resistance the chromium-rich coating is covered by an aluminum diffusion coating from a simple aluminum diffusion pack or one that has the aluminum mixed with chromium. Low temperature aluminum diffusion is more uniform when pack energizer is aluminum chloride or other material that does not generate nitrogen. A manganese-containing aluminizing pack gives better protection than a simple aluminizing pack, particularly against marine corrosion, and when there is a conversion coating applied over the aluminizing. Conversion coating mixture wets aluminized ferrous surface better when the surface has been treated with alkali to blacken it, and the black is then removed with the help of nitric acid. Aluminized superalloy can be heated in air to whiten it, then cleaned to give product having more adherent case. Also adding some lanthanum or yttrium to superalloy like WI 52 gives better high-temperature resistance. (Official Gazette)

• Research Organization: Originating Research Org. not identified
• NSA Number: NSA-29-016189
• Assignee: to Alloy Surfaces Co., Inc.
• Patent Number(s): US 3764371
• OSTI ID: 4362453
• Resource Relation: Patent File Date: 1970 Nov 18; Other Information: C23c9/02. Orig. Receipt Date: 30-JUN-74
• Country of Publication: United States
• Language: English

Related Subjects

N50120* -Metals
Ceramics
& Other Materials-Ceramics & Cermets-Preparation & Fabrication
N50110 -Metals
Ceramics
& Other Materials-Ceramics & Cermets-Corrosion & Erosion & Surface Phenomena
*ALUMINIUM- DIFFUSION COATING
*CHROMIUM- DIFFUSION COATING
*MAGNESIUM- DIFFUSION COATING
*TD- NICKEL- PROTECTIVE COATINGS
*TD-NICKEL CHROMIUM- PROTECTIVE COATINGS
ALUMINIUM CHLORIDES
BASES
DEPOSITION
NITRIC ACID
SURFACE TREATMENTS