Potassium-Doped Tungsten Bulbs Strengthen

Doped tungsten containing potassium atoms due to air bubbles leaving the high-temperature creep resistance tungsten improve mechanisms . In 1918, Americans Perth (A.Pacz) found that tungsten oxide reduction by adding trace amounts of silicon, aluminum , potassium oxide billet prepared by appropriate processing and heat treatment made ​​of tungsten wire has excellent high temperature creep resistance , is ideal incandescent filament material . Doped tungsten is still electronic , electric light source industry is an important basic material . The invention and production of doped tungsten although half a century of history, but due to the testing conditions , people on the micro- doping and Strengthening Mechanisms long failed to recognize , at different times have raised a variety of assumptions and inferences to explain . Therefore, doping and strengthening mechanisms always is a worldwide concern one of the few research topics .

Doped tungsten ordered the formation of potassium -doped tungsten bulb is caused by high-temperature creep resistance excellent basis for this argument is not only fully proved , but gradually made ​​a convincing theoretical explanation , thus forming strengthening and improvement of the potassium bubble theory . Potassium -doped tungsten bulbs and perfect the mechanism of strengthening due to development, has become one of a variety of ways to strengthen the development of new refractory metal materials in the applications.

Potassium reinforcement theory of bubble formation and development can be divided into the following three phases :

( 1 ) Assuming the inference stage . 1957 Si Wolin (R.A.Swalin) and Geissler (A.H.Geisler) proposed a linear arrangement , said dopant , that the doping agent is added during the sintering of tungsten billet maintained during long time the porous state, so that recrystallization grains are fully grown . Reich (G.D.Reich) , who also made ​​a similar linear arrangement dopant , said that the tungsten wire drawing process dopants in a tubular tungsten bronze compounds exist in the form fibers borders , these parallel filaments axis direction is tube-like in the recrystallization process will prevent or inhibit grain growth along the direction of the wire diameter , thereby forming a great aspect ratio of crystal growth . 1962 Milner (T.Miller) dissolving said dopant is proposed that a very small part of the dopant in dissolved form, dissolved particles and the interaction between dislocations , resulting in recrystallization grains grow to form . All these ideas corporations inferences and assumptions , the lack of adequate experimental basis , but to attract people's attention and promote further research has played a positive role.

( 2 ) theory and development phase. In 1967 , the library (R.C.Koo) , who used directly observed by transmission electron microscopy to annealing at a high temperature in the presence of tungsten dopant pressure generated by the vapor formed vesicles period Snow (D.B . Snow) confirmed the vesicles containing potassium atoms. Scholars from various countries were followed by X-ray energy dispersive spectroscopy , secondary ion mass spectroscopy , Auger electron spectroscopy and field ion microscope analysis of the most advanced electronic equipment for various states of doped tungsten microstructure and dopant the morphology and composition of the full system, experiments were observed and the results of each assay , based on the proposed mechanism of doped tungsten strengthen various theoretical explanation . Which the United States Library , Snow and China , who left Tieyong made ​​a more systematic analysis of experimental and theoretical explanations. 1967 to 1985 is potassium -doped tungsten bulbs reinforcement theory with precise experimental basis and the establishment and development period.

( 3 ) potassium bubble theory to the development of new high-strength material phase. Since 1985 , successive refractory metals and hard materials, the International Conference on Theoretical study on the expansion of the bubble potassium and materials to strengthening and toughening materials in the field of basic issues that combine in-depth study of trace impurities on the tungsten, molybdenum grain between adhesion and the electronic structure of grain boundaries , leading to embrittlement microscopic mechanism , and then discusses the harmful effects of eliminating impurities technical measures . In addition , the different regions at different temperatures additive dispersion strengthening and potassium doped tungsten bulbs strengthening mechanisms linking explore refractory material suitable for a variety of strengthening mechanisms combined effects of reinforcement theory . Strengthening and toughening mechanisms for a correct understanding of the design and development of new high-temperature materials provides a theoretical basis .


Tungsten Alloy Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-alloy.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com;sales@xiamentungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn
 

• < Prev
• Next >