Specialty Applications

Roll compacting facilitates the production of small coils in which minor compositional changes can be made during blending. Because roll compacting produces materials with uniform and reliable properties, many specialty materials are produced by these methods (Ref 6).

Specialty P/M strip produced by roll compacting includes various compositions of nickel-iron strip produced for controlled expansion properties and special copper-nickel-tin alloys. The latter must meet stringent property requirements, such as strength, formability, stress relaxation, electrical conductivity, solderability, and corrosion resistance. Casting of this material produces elemental segregation during solidification, which can be avoided by using P/M fabrication techniques.

Typical applications of roll-compacted strip materials include:

• High-purity nickel strip parts for heart pacemaker batteries

• Nickel-iron strip for resistor caps (Fig. 11)

• Ni-Fe-Co cans for glass-sealed electronic parts

• Ti-Al foils for composite manufacture (Ref 8 and 9)

Fig. 11 Typical roll-compacted nickel strip applications. (a) Pure nickel semiconductor caps. (b) Nickel-iron lead frame. (c) Nickel-iron Dual Inline Package integrated circuit. (d) Nickel-iron resistor end caps

Figure 12 illustrates a method for producing porous strip of pure nickel for alkaline battery and fuel cell electrodes. In this procedure, an electroformed nickel screen or mesh is fed into the center of the powder hopper and incorporated into the rolled strip to produce highly porous electrodes with adequate green strength. The same system can be used to feed wires into a green strip for extra strength.

Fig. 12 Rolling of strip from nickel powder. Designed to incorporate mesh into strip
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