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2013年7月12日星期五

Applications of Tungsten Copper Composites

Copper tungsten alloys are used where the combination of high heat resistance, high electrical and/or thermal conductivity, and low thermal expansion are needed. Some of the applications are in electric resistance welding, as electrical contacts, and as heat sinks. As contact material the alloy is resistant to erosion by electric arc. Tungsten copper alloys are also used in electrodes for electrical discharge machining and electrochemical machining.
The CuW75 tungsten copper alloy, with 75% of tungsten, is widely used in chip carriers, substrates, flanges and frames for power semiconductor devices. The high thermal conductivity of copper together with the low thermal expansion of tungsten allows thermal expansion matching to silicon, gallium arsenide, and some ceramics.
Copper Tungsten alloy with 70-90% of tungsten is used in liners of some specialty shaped charges. The penetration is enhanced by factor 1.3 against copper for homogeneous steel target, as both the density and the break-up time are increased. Tungsten powder based shaped charge liners are especially suitable for oil well completion. Other ductile metals can be used as binder in place of copper as well. Graphite can be added as lubricant to the powder.
The manufacturing process of Tungsten copper alloy is to press the refractory (tungsten or tungsten carbide), sinter the pressed compact at a high temperature, and infiltrate with copper. All of this is done under very closely controlled conditions. The mechanical and physical properties of Tungsten copper alloy vary with composition. The thermal and electrical conductivity increase with the amount of copper, while the hardness, strength, and resistance to mechanical wear increase with the amount of tungsten or tungsten carbide. The application determines the material choice.

Tungsten Copper EDM and ECM

Tungsten Copper EDM and ECM
Our tungsten copper composites are used worldwide for electrical discharge machining (EDM) and electrochemical machining (ECM) electrodes. All composite material is manufactured by the press, sinter, and infiltrate process; adhering to strict quality checks every step of the way. You can rely on the quality of our tungsten composites to provide consistent, homogeneous materials that yield high and even burning rates
Tungsten copper alloys are used worldwide for EDM (Electrical Discharge Machining) and ECM (Electrochemical Machining) electrodes. All material is manufactured by the press, sinter, and infiltrate process. Virgin tungsten powders are used, resulting in a consistent homogeneous material giving high and even burning rates. Tungsten copper is used in plunger/sinker applications where intricate definition is required, especially in tungsten carbide.

The Characteristics of Tungsten Copper Alloy

The machining and grinding characteristics of tungsten alloy are similar to those of hard grey cast iron. Being nonporous, standard water soluble coolants may be used if desired, but are not required. Each machine shop usually has its individual machining or grinding practice and, therefore, the information presented should be considered as a guide only.
Tool: Carballoy, grade 883 or equivalent. Grind tools with 0 deg. rake, 8-12 deg. clearance, and .010" to .025" nose radius. The nose radius can increase with the size of the work. For fine finish, stone small flat on tool parallel to work. Suggest resting stone on work when honing tool.
Turning & Boring: Roughing, approximately .030" deep and .020" per revolution feed. Finishing, .002" to.005" depth of cut and .001" to .002" per revolution feed. Turning speed, 300-500 surface feet per minute. Do not use lubricant or coolant.
Shaping: Tool Speed: 43" per minute for Tungsten Copper 25% alloy.
Depth of Cut: .030"
Feed: .020" per stroke
Milling: Drilling High Speed steel drills and taps may be used.
Through Tapping: Holes are recommended. Material must be firmly held. Hand feed-lubricant and cutting oil acceptable.
Rough Grinding: is best done with 80 grit resin bonded wheels of medium hardness; .015" per pass on Tungsten Copper 25% alloy.
Use water or water soluble oil coolant.
Joining: Material may be silver brazed, or copper brazed in a hydrogen atmosphere.
Copper Tungsten alloy is the composite of Tungsten and Copper, which own the excellent performances of Tungsten and Copper, such as heat-resistant, ablate-resistant, high-intensity, excellent thermal and electrical conductivity. It is easy to be machined. It is used widely in such industries as engine, electrical power, electron, metallurgy, spaceflight and aviation. Using CIP formation, sintered tungsten skeleton and infiltrating copper (silver) technology, large size and special shape products of tungsten-copper (silver) composites with 6-90 percent of copper are produced, such as electric contacts, electrode, refractory parts, heat sinks and parts of rocket, We can also produce sheet material, tubing, plate and other small products by mould pressing, extrusion pressing and MIM.
Tungsten copper alloys are used where the combination of high heat resistance, high electrical and/or thermal conductivity, and low thermal expansion are needed. Some of the applications are in electric resistance welding, as electrical contacts, and as heat sinks. As contact material the alloy is resistant to erosion by electric arc. WCu alloys are also used in electrodes for electrical discharge machining and electrochemical machining.
The CuW75 alloy, with 75% of tungsten, is widely used in chip carriers, substrates, flanges and frames for power semiconductor devices. The high thermal conductivity of copper together with the low thermal expansion of tungsten allows thermal expansion matching to silicon, gallium arsenide, and some ceramics. Other materials for this applications are CuMo alloy, AlSiC, and Dymalloy.

Copper Tungsten Alloys - Refractory Metal Composites

Copper Tungsten Alloys - Refractory Metal Composites
Eagle refractory metal composite materials are a combination of tungsten or tungsten carbide combined with copper or silver. The manufacturing process is to press the refractory (tungsten or tungsten carbide), sinter the pressed compact at a high temperature, and infiltrate with copper or silver. All this is done under very closely controlled conditions. The result is a relatively hard materials with superior arc and wear resistance, high physical properties at elevated temperatures, and good electrical and thermal conductivity.

Electrical Contact materials

Electrical contacts are subjected to extreme mechanical and thermal stresses during operation. For fractions of a second, temperatures rise to several thousand degrees as a result of the arcing. Only Tungsten Copper materials will stand these high temperature & aberration.
Tungsten Copper material has good resistance to arc erosion, mechanical wear, contact welding and good conductivity. They are usually selected for oil, gas, air or vacuum, devices. The contact surfaces will oxidize when switched in air. These press-sinter-infiltrate materials should only be considered for arcing surfaces in air when used as arcing tips, arc plates and arc runners. When switching with moderate contact arcing, the Tungsten Copper with a high copper content may give the lowest erosion. As arcing severity increases, the Tungsten Copper with the higher refractory content withstand arc erosion better. Tungsten Coppers are also used as arcing edges of selector switchblades in transformer tap changers.