Lanthanum is a chemical element , its chemical symbol is La, its atomic number is 57 , belonging to the lanthanide elements for rare earth metals is the most reactive metal in the air is easily oxidized. Lanthanum quarry alone accounted for 25% of total rare earth . A soft silver-white metal , malleable . With water effect. Soluble in dilute acid . Easily oxidized in air ; heating can burn to form oxides and nitrides. Heated in hydrogen generation hydride . It is the second most abundant rare earth elements , often along with other rare earth elements present in monazite , fluorocarbon lanthanum strontium ore . It is uranium, thorium or plutonium fission of radioactive products . It gives the refractive index of the special properties of the glass , the glass having a higher refractive index . Preparation of lanthanum general dehydration of hydrated lanthanum chloride , the use of calcium metal restore , or anhydrous lanthanum chloride electrolysis and after melting in the system. Used to manufacture an expensive camera lens . 138La is a radioactive half-life of 1.1 × 1011 , the trial was to treat cancer .

Lanthanum tungsten electrode is the European country in the 1980s with the hope for alternative thorium tungsten products, improved varieties, once launched, its excellent welding performance attracted much attention in the international welding industry and is very popular, especially by European Welding School in the pursuit, for this reason, the export volume of lanthanum tungsten electrode tungsten thorium behind , while in the domestic market awareness is not high. Its characteristics are the closest conductive properties of 2% thoriated tungsten electrodes , durable high burning rate of the current minimum .


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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 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 .

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 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.


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1970s Shanghai Bulb developed into cerium tungsten electrodes , then realized industrialization . Rare earth cerium than thorium (Th) has a higher electron emission features, but is a non- radioactive elements. Arc made ​​application performance comparison results : 2% ahead of Japan 2% cerium tungsten thorium tungsten, 4% better than 2% cerium tungsten, cerium tungsten ( No 4% thoriated tungsten electrode ) , specific performance: arc high compression , slender arc stability, energy concentration, arcing power or low voltage, arc breaking spacing, life doubled. 4% cerium tungsten electrodes applications , capturing the processing of cotton textiles shrink " shrink machine key components damping damping stick " plasma thermal spraying the surface finish of the storm , breaking the monopoly of foreign companies , foreign exchange value of the needle cotton greatly increased. Ministry of Geology research with platinum foil tube sealing technology, the requirements do not make the barrel of liquid volatile chemicals reduction of the problem, but also with 4% cerium tungsten electrodes only solution .

MEW already provides that where more than ten thousand kilowatts generator must Shanghai Bulb cerium tungsten electrodes welding , quality assurance. Defense with a laser device is life after cerium tungsten electrodes with thorium tungsten electrode from the original ten minutes , up to hundreds of hours of energy and light load efficiency is also improved, the battle to solve practical problems . 1982 China's offshore missile tests, foreign -made laser performance over competing devices , including cerium tungsten electrodes show a huge role . In addition, in beacon lights, road lights aircraft , fundus fluorescein camera lights , lamps and other lighting layout more than 140 kinds of gas discharge light source applied and achieved good results . Currently, 2% cerium tungsten electrodes have been included in the international standard , China has also developed a national standard cerium tungsten electrodes , so that the formation of the first in the world can replace thoriated tungsten series of international standards to add 1%, 2 %, 3% , 4% of the non-radioactive standard cerium tungsten electrodes .


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Cerium tungsten electrodes in tungsten adding rare earth cerium oxide powder metallurgy and rolling through grinding and polishing process made of tungsten electrode products, is the earliest production of non-radioactive tungsten electrodes product that is characterized by the low current conditions has excellent arc performance , dimensional arc current is small . Therefore, it is commonly used in pipes, stainless steel products and welding of small precision parts . Conditions at low current DC electrode diameter 2.0mm or less , cerium tungsten electrodes thorium tungsten electrode is preferred alternatives.

Grade , Composition, Color , Work Function

Model grades Added Impurity Impurity quantity% doping doping % Other Impurities% of its

He miscellaneous mass % Tungsten% tungsten % Electric discharged power Color sign electron work function color

WC20 CeO2 1.80-2.20 <0.20 margin The rest 2.7-2.8 Ash Grey

The advantage is cerium tungsten X- ray dose and antioxidant properties than thorium tungsten have been greatly improved ; electronic thorium tungsten electrode work function than about 10 %, the arc easier and better arc stability . Also cerium tungsten chemical stability, cathode spot is small, low pressure drop, burning and less , so is the most widely used TIG welding a tungsten electrode . Commonly used tungsten chemical composition and grade of pure tungsten W1 W ≥ 99.92 SiO2 ≤ 0.03 Fe2O3Al2 ≤ 0.03 Mo ≤ 0.01 CaO thorium tungsten WTH-7 W margin other impurities is not more than the total mass fraction of 0.15%.

Cerium tungsten WCe-20 W margin CeO1.8-2.2 SiO2 ≤ 0.06 Fe2O3AI2O3 ≤ 0.02 Mo ≤ 0.01 CaO ≤ 0.01 cerium tungsten low electron work function , high chemical stability , allowing current density, non-radioactive , is currently a commonly used electrodes of pure tungsten high melting and boiling points , easy to melt volatile , burning, cutting-edge , less pollution, but the electron emission is poor, is not conducive to the stability of arc burning. Thorium tungsten electron emission capability, allowing high current density arc burning more stable, but with a certain radioactive elements thorium , promote the application be affected. Zirconium tungsten electrode on the need to prevent contamination of the base metal under special conditions , you can use this tungsten . This is easy to maintain the hemispherical tip of the electrode , suitable for AC welding .


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In one aspect, a bucking bar device for use in riveting parts together is described. In one embodiment, the bucking bar device includes a bucking bar, and a sleeve positioned so that the bucking bar extends within the sleeve. One end of thesleeve is configured to be positioned adjacent to at least one of the parts.

In another aspect, a sleeve for use with a bucking bar device including a bucking bar is described. The sleeve includes a cylinder engaging sleeve member having threads on an internal surface, and an intermediate sleeve member having threads onan outer surface. The intermediate sleeve member is in threaded engagement with the cylinder engaging sleeve member. A non-marring sleeve member is at least partially inserted into the intermediate sleeve member and extends therefrom.

In yet another aspect, a method for installing a rivet is provided. The method includes the steps of setting a recess between an impact face of a bucking bar device and a reference surface of a bucking bar sleeve assembly operatively attachedto the bucking bar device to form a bucking bar and sleeve assembly, placing an end surface of the bucking bar sleeve assembly around a buck tail of the rivet to be set and against the surface of the material to be riveted, and compressing the buck tailof the rivet using the bucking bar and sleeve assembly until the impact face of the bucking bar no longer impacts the buck tail of the rivet.

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Here is an excellent quick and short guide on how to avoid buying fake gold coins and fake gold bars, with some background on the recent scare stories about counterfeit coins sourced from China. By the way, never bite a gold coin to test it - you'll either ruin the coin or break your teeth.

It's good to read that fake bullion gold Eagles and fake gold Maples, at least, are extremely rare; but as for historical gold coins of very high value, fakes are more likely, since there is such a great potential profit over and above the gold value for the counterfeiters.
In dealing with the subject of fake gold bars, the author also gives the best informed account I've read about why the recent 'fake gold bars made of tungsten' story is an urban myth.

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Now that the economy is collapsing, investors are becoming more interested in gold. Here's an item from PopSci that says it wouldn't be too difficult to make convincing fake gold bars out of gold-plated tungsten (which costs $30 a pound compared to $12,000 a pound for gold).

start with a tungsten slug about 1/8-inch smaller in each dimension than the gold bar you want, then cast a 1/16-inch layer of real pure gold all around it. This bar would feel right in the hand, it would have a dead ring when knocked as gold should, it would test right chemically, it would weigh *exactly* the right amount, and though I don't know this for sure, I think it would also pass an x-ray fluorescence scan, the 1/16" layer of pure gold being enough to stop the x-rays from reaching any tungsten. You'd pretty much have to drill it to find out it's fake.   

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