The History Of Tungsten Wire

 

 

 

 

For many years, tungsten was one of the rare elements and did not become of industrial importance until 1847, when Oxford patented the manufacture of sodium tungstate, tungstic acid and tungsten from cassiterite (cassiterite). . Oxland's second patent, filed in 1857, described a method for making the iron-tungsten alloy that forms the basis of modern high-speed steel.

 

However, the metal itself was not used until nearly fifty years later, when it was first used to make filaments for incandescent lamps. From the time Swan demonstrated his eight- and sixteen-candlepower carbon lamps at Newcastle in 1878, the search began for a more satisfactory filament material than carbon. The efficiency of early carbon lamps was about 1.0 lumens per watt, improving over the next 20 years to about 2.5 lumens per watt through improved carbon preparation methods.

 

This was further improved to about 3.0 lumens per watt in 1898 by electrically heating the filament in an atmosphere of petroleum vapor, which caused carbon to deposit in the pores of the filament and gave it a bright metallic appearance. At the same time A. Von Welsbach successfully produced the first metal wire using osmium; platinum had been previously attempted, but its melting point was relatively low at 1774°C. hindering its successful development. Lamps using osmium filaments have an efficiency of approximately 6.0 lumens per watt. Since osmium is the rarest platinum metal, it could never be used on a large scale.

 

Tantalum has a melting point of 2996°C compared to 2700°C for osmium and was used extensively for wire drawing from 1903 to 1911 following the research of Siemens and Von Bolton of Halsk. Lamps with tantalum filaments have an efficiency of approximately 7.0 lumens per watt. The development of the use of tungsten began around 1904, with exclusive use beginning around 1911.

 

Modern tungsten lamps for general lighting purposes are brushed and have an efficiency of about 12 lumens per watt, while high-power lamps are tungsten. Wattage efficiency is up to about 22 lumens per watt. Modern fluorescent lamps, although they use tungsten cathodes, do not rely on tungsten for their efficiency, which is about 50 lumens per watt.