10% Cobalt Copper

Lead-freeCorrosion Resistance Improver Jewelry Alloy Addition Shot Form Controlled Cobalt Addition

Cobalt copper master alloy (90% Cu, 10% Co) for corrosion resistance improvement in copper alloys. Shot form for jewelry and foundry additions.

Solidus

1,994°F (1,090°C)

Liquidus

2,102°F (1,150°C)

Density

0.323 lbs/in³ (8.95 g/cm³)

Primary Elements

Cu · Co

Nominal Composition

10% Co, 90% Cu

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Product Overview

10% Cobalt Copper is a copper-cobalt master alloy with a nominal composition of 90% Cu and 10% Co. Cobalt additions to copper alloys are made primarily to improve corrosion resistance particularly in aggressive industrial and marine environments and to improve strength and hardness through solid solution hardening. Cobalt also improves the elevated-temperature strength retention of copper alloys used in high-temperature service. In specialty jewelry alloys cobalt additions produce distinctive color effects and improve tarnish resistance of copper-base alloys. In engineering copper alloys cobalt improves corrosion resistance in acid and alkaline environments and contributes to the overall performance of complex multi-component copper alloys. Supplied in 2-14 mesh shot form for both jewelry casting studio and foundry charge addition use.

Available Forms

2-14 Mesh Shot

Product Code

4907

Technical Info

Thermal Properties

Melting Point (Solidus)1,994°F (1,090°C)

Melting Point (Liquidus)2,102°F (1,150°C)

Physical Properties

Density (imperial)0.323 lbs/in³

Density (metric)8.95 g/cm³

Primary ElementsCu · Co

Lead FreeYes

Key Features

Corrosion Resistance ImproverJewelry Alloy AdditionShot FormControlled Cobalt Addition

Solubility Note

Dissolves readily in molten copper and copper alloy heats at standard casting temperatures; the copper matrix allows rapid cobalt entry without the dissolution problems of elemental cobalt addition.

Nominal Composition

90% Cu
10% Co

Frequently Asked Questions

Common technical inquiries regarding 10% Cobalt Copper

Cobalt improves copper alloy corrosion resistance primarily in reducing acid environments (hydrochloric and sulfuric acids at moderate concentrations), alkaline solutions, and industrial atmospheres containing sulfur compounds. The improvement mechanism involves cobalt participating in the formation of a more adherent and protective surface oxide film. The benefit is most pronounced in copper-cobalt alloys exposed to fluctuating oxidizing-reducing conditions where standard copper alloys suffer accelerated selective attack.

Cobalt additions to copper alloys shift the color slightly toward a cooler less saturated copper tone at low levels (under 2%) and produce more significant color modification at higher additions. At 10% Co the high cobalt content creates a distinctive appearance that differs from standard copper, brass, and bronze alloys. For jewelry applications small additions of 0.5-2% Co are used to alter color tone and tarnish behavior creating unique appearance characteristics not achievable with standard alloy systems.

The 2-14 mesh shot form provides accurate weighing of small quantities in the gram-to-few-gram range typical of jewelry casting studio additions where ingot or slab would be difficult to divide accurately. The small particle size also ensures rapid complete dissolution in the small crucibles typical of studio induction furnaces. For foundry production operations making larger heats multiple shots are simply weighed as a batch — the free-flowing shot form is compatible with both manual weighing and automated vibratory dosing systems.