Bi-Axially Textured Ni Tapes Fabricated by a Cold Rolling Process of Nickel Powder Compacts

Scott Bartz17 September 2007

Rolling: metal forming process (Compression)

Hot RollingCold Rolling

Process: Ni and Ni-W powder compacts were cold rolled into tapes.

Purpose: Discuss the effect of the processing variables on the texture development of the Ni and Ni-W tapes for YBCO coated conductors.

When Ni ingots are formed by melting and casting, impurities can enter from the crucible and mold used.

Powder Metallurgy was used to help reduce impurities in the ingots.

1) Powdered Ni is weighed and Packed (10 mm)

2) Compacted by cold iso-static pressing (8.3 mm)

3) Sintered for densification (7.2 mm)

4) Cold rolled (5% reduction) to final thickness (100 μm)

5)Texture annealed

“Bi-axially Textured Ni Tapes Fabricated by a Cold Rolling Process of Nickel Powder Compacts”, IEEE Transactions on Applied Superconductivity, Vol. 13, NO. 2, Jun 2003, pp. 2583.

Results and Discussion

“Bi-axially Textured Ni Tapes Fabricated by a Cold Rolling Process of Nickel Powder Compacts”, IEEE Transactions on Applied Superconductivity, Vol. 13, NO. 2, Jun 2003, pp. 2584.

Tensile Test of sintered rods

Results and Discussion

(a) Many pores at the grain boundary.

(b) No pores when annealed for 12 minutes.

Microstructures of Ni tapes

The higher the sintering temperature, the more ductile the Ni rods.

The surface roughness of the Ni and Ni alloy tapes were 3 nm

Important for those working with high temperature superconductors

Lack of explanation in the concluding section

No tables used

More variables could have been incorporated into the experiment

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[2] ------, “Texture formation and grain boundary networks in rolling assisted biaxially textured substrates and in epitaxial YBCO films on such substrates and in epitaxial YBCO films on such substrates,” Micron, vol. 30, pp. 463-478, March 1999.

[3] D.P. Norton et al., “Epitaxial YBa2Cu3O7 films on rolled-textured metals for High-temperature superconducting applications,” Mater. Sci. and Eng. B, vol. 56, pp. 86-94, 1998.

[4] B. De Boer et al., “Cube textured nickel alloy tapes as substrates for YBa2cu3O7- coated conductors ,” Acta mater., vol 49, pp. 1421-1428, January 2001.

[5] T. Petrisor et al., “Development of biaxially aligned buffer layers on Ni and Ni-based alloy substrates for YBCO tapes fabrication,” IEEE Trans. Appl. Supercon., vol. 9, pp.2256-2259, June 1999.

[6] J. Eickemeyer et. Al., “Nickel-refractory metal substrate tapes with high cube texture stability,” Supercon. Sci. and Tech., vol. 14, pp. 152-159, March 2001.

Please giveme an “A”!!!