Platinum-gold alloys, spinnerets

Gold and gold-based alloys ate used for corrosion-resistant equipment. Gold—platinum alloys, 75 Au-25 Pt or 84 Au-15 Pt-1 Rh, ate used as cmcible material for many molten salts (98). Spinnerets for rayon manufacture ate based on the Au—Pt system which exhibits a broad miscibility gap in the soHd state so that the alloys can be age-hardened. Spinneret alloys contain 30—40% or mote platinum modified by small additions of usually rhodium (99). Either gold or gold—platinum alloys ate used in mpture disks for service with corrosive gases (100). 

Alloys of gold and the platinum metals are used in the manufacture of artificial silk. The viscous liquid used to produce the silk is extruded through fine holes in a spinneret. As these holes may be only 0 003 nch n diameter they must be perfectly smooth, and gold-platinum metals alloys serve the purpose admirably. 

The spinnerets are made of various materials depending on the spinning solutions. Precious metal alloys of gold, platinum, iridium, as well as rhodium, tantalum, and glass are used. The shape and size of the boreholes differ. For the production of viscose fibers, spinnerets have 30,000 to 90,000 capillaries. Acrylic fibers are spun according to the wet-spinning method with 40,000 to 150,000 holes per spinneret (Rogowin, 1982). 

The body of the spinnerets consists of gold or platinum alloys. The orifices have a diameter between 50 and 250 pm, depending on the desired thickness of the fiber. In filament spinning, the number of holes is equal to the desired number of capillaries in the yam (18-1000). In staple fiber production, the number of holes may surpass 90000. 

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