Issued October 2000
Supersedes May, 1970
TM
Metcoloy #33 Wire ®
Technical Bulletin #10-026
®
Metcoloy #33 Wire
Metcoloy #33 is a nickel-chromium wire manufactured exclusively for flame spraying. It is particularly
suitable for applications where resistance to heat corrosion is required.
Metcoloy #33 is certifiable as meeting Department of Defense specification MIL-W-6712B, Table II,
Nickel Chromium-B.
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Metcoloy #33 can be sprayed with any Metco metallizing gun, using any fuel gas.
Applications
Metcoloy #33 is required when applying Metco Systems 33 and 45 for heat corrosion.
Metco System 33 protects iron and steel against temperatures ranging from 1600 - 1800º F, in the
presence of corrosive gases which do not contain large amounts of sulfur. This system uses Metcoloy
#33 .010" thick, and one coat of Metcoseal M, which contains metallic aluminum.
When first heated, the aluminum penetrates through the sprayed coating and alloys readily with the
base metal, forming a chromium-nickel-aluminum-iron alloy. This helps seal the pores against
penetration of gases. Since no appreciable amount of aluminum remains on the surface, the
chromium-nickel alloy is exposed to hot gases. Therefore the coating will not withstand the corrosive
action of strong sulfur gases.
Metco System 45 provides maximum protection against heat corrosion, withstanding even strong
sulfur gases up to 1800º F. It uses Metcoloy #33 .015" thick, pure Aluminum .004" thick, and one coat
of Metcoseal M.
When first heated, the aluminum forms a chromium-nickel-aluminum-iron alloy bond with the base
metal. The large amount of aluminum used also causes a more complete chromium-nickel-aluminum
alloying throughout the coating. The pores of the sprayed metal coalesce into small isolated holes that
are completely surrounded by solid metal. Thus the coating, while still somewhat porous, becomes
impervious to the penetration of gases.
Use Metcoloy #33 for heat corrosion protection on iron and steel. Examples include: aircraft exhaust
stacks; aluminum ingot molds, melting and pouring pots; annealing covers; carburizing boxes; crown
sheets; cyanide pots; damper plates; furnace conveyors, structural steel parts, tuyeres; heat treating
pots; kiln parts; magnesium pouring pots and super-heaters; pyrometer tubes and brackets; salt pots;
wire annealing retorts.
#10-026 Metcoloy #33 Wire 2
Typical Composition
Nickel 60%
Chromium 16%
Silicon 1.5%
Iron Balance
Physical Properties
Melting point: 2350º F. (approx.)
Spraying
Parameters for spraying Metcoloy #33 are shown in the Metco Gun Instruction Manual.
Finishing
Coatings of Metcoloy #33 may be machined or ground. Use the parameters for Metcoloy #1 in Vol. I of
the Flame Spray Handbook under "Finishing".
Hazards
Chromium alloy fumes are extremely hazardous. Complete respiratory protection must be provided for
all personnel wherever chromium alloys are being sprayed.
The information provided in this document is for the convenience of Sulzer Metco’s customers for the
purpose of evaluation and proper use of the Sulzer Metco product(s) described herein. This document
and the information contained herein is the property of Sulzer Metco and shall not be used, disclosed,
or reproduced in whole or in part for any purpose other than for the use of said product(s). Nor shall
this information be used in any way with goods not manufactured and sold by Sulzer Metco. Sulzer
Metco makes no warranties, express or implied, as to the information contained herein.
#10-026 Metcoloy #33 Wire 3
