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Fabricating copper tungsten alloy components requires specialized techniques due to the material's high hardness and density, as well as the potential for tungsten depletion during processing. Here are the primary fabrication techniques used for manufacturing copper tungsten components:
Powder Metallurgy
Mixing and Blending:
Copper and tungsten powders are blended in precise ratios to achieve the desired composition (typically 10% to 50% tungsten by weight).
Compaction:
The mixed powders are compacted under high pressure (typically hydraulic or mechanical presses) to form a green compact with the desired shape and dimensions.
The compaction process must achieve sufficient density and uniformity to ensure proper sintering.
Sintering:
The green compacts are sintered in a controlled atmosphere furnace at temperatures below the melting point of copper (typically around 1100°C to 1200°C).
During sintering, the powders bond together, resulting in a solid, porous structure known as a sintered preform.
Infiltration (Optional):
In some cases, the sintered preforms may undergo a secondary process called infiltration, where liquid copper or other metals are infiltrated into the porous structure.
This improves density, strength, and ductility while reducing porosity.
Final Machining:
After sintering and possibly infiltration, the components are machined to achieve the final dimensions, tolerances, and surface finishes required for the application.
Specialized machining techniques such as electrical discharge machining (EDM) or grinding may be necessary due to the material's hardness.
Hot Pressing
Preparation:
Copper and tungsten powders are mixed and blended as in powder metallurgy.
Hot Pressing:
The mixed powders are compacted and simultaneously heated under very high pressures (typically in excess of 100 MPa) and temperatures (above 1200°C).
This process results in a fully dense CuW alloy with minimal porosity and excellent mechanical properties.
Post-Processing:
Hot pressed CuW components may require final machining or finishing to achieve the desired specifications.
Electrodeposition
Electroforming:
Copper tungsten can be electroformed onto a substrate to create complex shapes or thin coatings.
Electroforming involves electrodeposition of copper-tungsten alloy onto a conductive mandrel or mold, followed by separation from the mold.
Machining
Conventional Machining:
CuW components can be machined using traditional methods such as turning, milling, drilling, and grinding.
Specialized cutting tools and techniques are often necessary due to the material’s hardness and abrasiveness.
Joining Techniques
Brazing:
Components can be joined using brazing techniques where a filler metal with a lower melting point than the CuW alloy is used to bond parts together.
Brazing requires careful control of temperature to prevent melting or compromising the properties of the CuW alloy.
Fabricating copper tungsten components involves a combination of powder metallurgy, hot pressing, machining, and in some cases, electroforming and joining techniques. Each method offers unique advantages depending on the desired shape, size, and performance requirements of the final component. Selection of the appropriate fabrication technique depends on factors such as complexity of the part, dimensional accuracy, production volume, and specific application demands.
