Cerium is a chemical element , its chemical symbol Ce, atomic number 58 , atomic weight 140.115 , belonging to the lanthanide elements, but also one of the rare earth elements . Element name comes from the asteroid Ceres, the English name . 1803 German chemist Klaproth , Swedish chemist Berzelius discovered the cerium oxide , respectively . Cerium has four kinds of natural stable isotopes : cerium 136,138,140,142 . Cerium content in the crust of about 0.0046% , is the most abundant of the rare earth elements . Gray soft metal . In monazite accounted for over 40% of total rare earth . Cerium chemically active , firing in air using Daogua ie , soluble in acid , insoluble in alkali . Cerium is iron gray metallic , malleable , melting point 799 ° C, the boiling point of 3426 ° C, density of 6.657 g / cm ³. Cerium is in addition to the rare earth elements europium outside the most active . Cerium oxide at room temperature, it is easy ; slow decomposition in cold water , hot water reaction speed ; most cerium salt solution as its orange-red to orange-yellow , with a strong anti- magnetic properties and oxidation. Cerium oxide for polishing precision glass products, but also do glass to color agent and used to produce colored glass , cerium nitrate used in the manufacture incandescent hood .

Stainless steel electrode melting point of pure tungsten (3650K), the electron emission capability, high modulus , low vapor pressure , the first to be used as an electron -emitting material , but the pure tungsten emission efficiency is low , and in the formation of a high temperature recrystallization equiaxed grain structure will become brittle and easy to break. To overcome these shortcomings , countries Materials workers dedicated to research and development of new electrode materials , tungsten -based doping several high melting point, low power electronic escape rare earth metal oxides, can improve the recrystallization temperature , and can activate the electron emission . However, in the rare earth tungsten electrodes on the basis of research , despite some achievements , but the current global market, replace the use of tungsten electrodes still a long way .

1913 Pinch (Pintsch) found that tungsten - thorium dioxide electrode material in pure tungsten with 2% ( mass fraction ) of about thorium dioxide , which escapes power reduction is reduced to nearly half of 2.63eV ( pure tungsten is 4.55eV), greatly improving the emission efficiency of up to 50mA / W ~ 70mA / W ( pure tungsten electrodes by carbonization only 25mA / W ~ 40mA / W). Moreover tungsten - arc thorium dioxide and stability performance greatly improved than that of pure tungsten . But thorium is a natural radioactive elements, its long half-life of α -ray 1.4 × 1014 years, the production and use of radioactive pollution on the environment and human health hazard ; growing environmental awareness restricts its development, but tungsten - thorium dioxide electrode arc stability and durability can not meet the growing demand for welding technology , so countries have been conducting research materials and workers to develop new generation of thorium tungsten electrode material .


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Stainless steel electrode melting point of pure tungsten (3650K), the electron emission capability, high modulus , low vapor pressure , the first to be used as an electron -emitting material , but the pure tungsten emission efficiency is low , and at a high temperature to form equiaxed recrystallized shaped grains become brittle and easy to break. To overcome these shortcomings , countries Materials workers dedicated to research and development of new electrode materials , tungsten -based doping several high melting point, low power electronic escape rare earth metal oxides, can improve the recrystallization temperature , and can activate the electron emission . However, in the rare earth tungsten electrodes on the basis of research , despite some achievements , but the current global market, replace the use of tungsten electrodes still a long way .

In our country the 1990s, in order from the system with excellent performance and pollution tungsten electrode, tungsten trioxide powder of lanthanum oxide is added , after reduction , suppression, melt down , swaging , stretching lanthanum tungsten electrode was obtained . After analysis, the lanthanum of the tungsten electrode electrical performance than cerium tungsten and tungsten thorium , lanthanum, tungsten and lanthanum oxide evaporation rate is low migration rate , to form a better lap dovetail microstructure , has good high temperature resistance creep. High-energy ball milling and vacuum hot pressing sintering prepared bulk nanocrystalline tungsten - lanthanum oxide electrode materials, the effects of different lanthanum oxide nanocrystalline tungsten content on the electrical properties of the electrode material , while using scanning electron microscopy and energy dispersive spectrometer measured fuel La arc electrode tip distribution and microstructure . The results showed that: nanocrystalline tungsten - lanthanum oxide electrode was superior to the conventional powder metallurgy coarse-grained tungsten electrodes . When the lanthanum oxide content of 6% to 8% , the thermal electron emission capability and stability of the best , but with increasing the content of rare earth lanthanum oxide , lanthanum tungsten electrode moldability and processability more difficult.


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Stainless steel electrode melting point of pure tungsten (3650K), the electron emission capability, high modulus , low vapor pressure , the first to be used as an electron -emitting material , but the pure tungsten emission efficiency is low , and in the formation of a high temperature recrystallization equiaxed grain structure will become brittle and easy to break. To overcome these shortcomings , countries Materials workers dedicated to research and development of new electrode materials , tungsten -based doping several high melting point, low power electronic escape rare earth metal oxides, can improve the recrystallization temperature , and can activate the electron emission . However, in the rare earth tungsten electrodes on the basis of research , despite some achievements , but the current global market, replace the use of tungsten electrodes still a long way .

Cerium tungsten is to replace thoriated tungsten contamination with radioactive material and developed a new type of tungsten electrode material , the former Soviet Union in the 1960s, the development of new electrode materials have been reported , China's Shanghai bulb factory in 1973 began to study the W-CeO2 electrode , the first successful trial and application of the International organization for Standardization and has been included in non- melting polar standards . Most foreign countries, the use of pure tungsten powder mixed with cerium compounds prepared to take direct cerium tungsten powder. Country through the use of wet blue tungsten doped ceria , disposable reduction, pickling, isostatic pressing , rolling and other processes developed by cogging cerium tungsten electrodes , tested and used to indicate that the developed cerium tungsten powder of high purity, good suppression performance and sintering properties ; cerium cerium tungsten blanks content uniformity , good processing properties . Electrodes consistency, arc , good performance, the user has won wide acclaim. Practice has proved that the small size of cerium tungsten electrode tungsten electrode welding succeeded in replacing thoriated tungsten , but in AC welding electrodes , gas discharge light source and other aspects still can not completely replace thoriated tungsten , cerium tungsten electrodes and there arc poor life expectancies and other deficiencies.


Tungsten Alloy Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-alloy.com
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