Doped Tungsten Production Processes

Carolina (T.Millner) in 1931 will this improvement does not sag effect is known as "GK effect ." Then mixed tungsten -doped tungsten production process lengthy production processes , including tungsten smelting, processing of powder metallurgy and plastic preform several major phases . Preparation of tungsten billet billet production of tungsten used usually prepared by powder metallurgy , which includes the preparation of tungsten oxide , doped tungsten powder preparation , pickling, and pressure- sintering process . Preparation of tungsten oxide doped tungsten production is usually chosen by Jones Lang tungstate (APT) as raw materials . Preparation paratungstic from tungsten acid Holderness addition to traditional classical technique , but in the 1950s the international community to carry out extraction and ion exchange method of research, China in the 1970s also used these processes , thereby simplifying the process, improved recovery of tungsten . Industrial preparation of tungsten oxide in two ways :

(1) At a temperature of 500 to 800 ℃ calcined paratungstic acid obtained by the yellow tungsten trioxide ;

( 2 ) Temperature at 400 to 600C in a reducing gas atmosphere at reduced paratungstic acid blue tungsten oxide .

Blue tungsten oxide there is no fixed formula and uniform chemical composition , the main phases money tungsten bronze (ATB) and tungsten oxide . Followed tungsten trioxide , in a reducing atmosphere at a higher temperature will appear in the carbon filament yarn and buttons are spades replaced wire , but thallium low melting point, and thus the operating temperature and luminous efficiency is low . 1903 , according to Jay zafirlukast (A.Just) and Hannah door (F.Hannaman) patents, Hungary for the first time to create a tungsten filament. It is the carbon filament of hydrogen containing tungsten oxyhalide steam heated to high temperatures by the current , the carbon was completely replaced tungsten . Incandescent filament thus obtained contain more or less of carbon , not brittle quite serious , and in the use of the lamp , the filament continued densification , and thus the electrical parameters of the filament will change . In 1904, Jay zafirlukast and Hanna door recognizes the impact of carbon on the brittleness , using carbon- tungsten compound is mixed with a binder , and then extruded into filaments , and then heated in hydrogen reduced to metal . This method is very brittle tungsten obtained , but because of its much better light efficiency , or replacing the carbon filament , hungry for the production of filaments and filament lamps bear . These methods are not prepared thin tungsten wire. To solve this problem , in 1907 , a low nickel content of the tungsten alloy available, it is prepared by machining , but serious brittleness hindered its application .


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