Wollaston wire
A Wollaston wire is a very fine wire made of platinum with a diameter of less than 0.001 mm. The wire is named after the British physicist William Hyde Wollaston , who was involved in the manufacture of these very fine wires at the beginning of the 19th century. Wollaston wires are among the thinnest wires.
The original and current manufacturing method involves several process steps. The platinum wire is first drawn to a diameter of approx. 0.08 mm, thinner diameters can not be reached directly by wire drawing , as the material tears in the process. The platinum wire is then galvanically coated with a layer of silver until the diameter is about 2 mm. The wire obtained in this way now consists of a thin platinum core with a thick silver jacket and is drawn repeatedly until the desired diameter of the platinum core is reached (silver and platinum are proportionally thinner). Platinum diameters down to just under 1 µm are produced. Since such extremely thin wires cannot be handled correctly and they also have to be fastened, the entire thicker jacket wire is mounted in the relevant device (with clamping or soft soldering) and only then is the platinum core exposed at the required point. This is done using 10% nitric acid , which dissolves the silver and leaves the platinum behind.
Wollaston wires were used in the area of mirror galvanometers and crystal detectors in detector receivers , radio devices from the early days of radio broadcasting and the single-thread electrometer according to T. Wulf. The Wollaston wire served as a contact wire on the crystal for demodulating the broadcast signal. Later applications of platinum wire, which are still common today, are in the field of temperature measurement and high-frequency measurement technology .
Web links
- Index of Materials - Wollaston wire - Condition. Retrieved December 26, 2012 .
Individual evidence
- ↑ About Wire, MIT script. (PDF; 153 kB) Accessed December 26, 2012 .
- ^ A. Fantom: Radio Frequency and Microwave Power Measurement . Institution of Engineering and Technology, 1990, ISBN 0-86341-120-7 , pp. 75-76 .