Tungsten & Sapphire Growth Furnace Price

Tungsten Crystal Growth during Hydrogen Reduction of Tungsten Oxide (I)

Details: Category: Tungsten Information; Published on Thursday, 05 February 2015 18:26; Written by cq; Hits: 1615

In these years, significantly incremental enhancements and specialized developments in the area of hardmetal continued shift towards ultra-fine and ultra-coarse grades. Compared with conventional cemented carbide (middle grain or fine grain carbides), ultra-coarse grain cemented carbides(＞5µm) demonstrate good fracture toughness and thermal fatigue resistance. Thus, they attract much attention from different departments in the area of industry. Currently, it is widely applied in many fields and found increasing usage in areas such as milling tools, punching dies, and boring drills. Coarse grain W and WC powders are key materials for ultra-coarse grain cemented carbides producing. The industrially established method of preparing tungsten and carbide is the hydrogen reduction of tungsten oxide, tungstic acid or ammonium para tungstate at 900-1 200℃ or even higher temperature, initially to the metal powder followed by carburization. The average particle size of the powder obtained in this way is below 12 µm (Fsss).

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Research Status and Prospects of WO3-based Gas Sensor

Details: Category: Tungsten Information; Published on Thursday, 05 February 2015 18:17; Written by cq; Hits: 1726

Tungsten oxide is usually used to fabricate gas sensor to monitor the toxic gases or some exhaust gases in the air. The gas sensing properties of WO3 may be improved by optimizing itself characteristics (size, surface morphology, shape and crystalline structure) . Thus the hydrothermal method for preparation of WO3 attracts considerable attentions. At present, most of work has been devoted to the improvement of sensitivity，the reducing of concentration of target gas and the increase of gas types.

In fact, these aspects all gain well advancement by optimizing the grow method, dopant and electrode. However, the WO3-based gas sensor just usually performed well above 200℃. This temperature range limits the wide application of WO3-based gas sensor. Therefore, seeking approaches to reduce the working temperature may be the next goal. On the one hand, seeking new dopant material to change the gas sensing characteristics of WO3 is a common way. On the other hand, controlling the preparation conditions accurately and making use of the very assisting agents to optimize the relative characteristics of WO3 are the technique measures.

In addition, change the manner of WO3-based sensors for gases detection. Do not monitor the changes of electrical properties of WO3-based sensors. Recording the changes of optical properties of WO3-based sensors is also used to analyze the gas sensing response. This is because the optical properties will change when the WO3-based sensors exposure under the target gases.

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Magnetic Dartboard

Details: Category: Tungsten Information; Published on Thursday, 05 February 2015 18:10; Written by xsh; Hits: 571

Dartboard is divided into different areas. Each region has a corresponding value, the magnetic dartboard can be carried out at any time is an all ages event . if darts landed on red and green color of the outer ring, then the score is twice the corresponding areas score. The dartboard includes a target board, a holding pole and two closure members. The target board includes a magnetic rubber sheet having a rectangular shape and containing iron, the two sheets of cotton flannel being attached to both surfaces of the magnetic rubber sheet and having raisings on their outer surfaces, and an upper fitted piece attached to the upper end of the front surface of one of said two sheets of flannel.

Each region has a corresponding value, if darts landed on red and green color of the outer ring, then the score is twice the corresponding areas score. For example, the double-digit area if the dart falls below 18, then the score is 36. Understand the inner red and green color score. If the magnetic landed on the red-green color of the inner ring, the score is the score three times the corresponding area. For example, if three times the area of magnetic dartboard falls under 18, then the score is 54. Learn dartboard central "bull's-eye" score. "Bull's-eye" is divided into two areas, inner (usually red) is called "double bull's-eye", the outer ring (usually green) called "single bull's-eye." The rest of the region on the dartboard is divided into 20 zones, each also has a specific value. The most common situation is black or yellow magnetic dartboard landed area, when the score is the number that corresponds to the region.

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Dartboard with Magnetic Rubber Sheet

Details: Category: Tungsten Information; Published on Thursday, 05 February 2015 18:15; Written by xsh; Hits: 513

Disclosed herein is a dartboard with a magnetic rubber sheet. The dartboard includes a target board, a holding pole and two closure members. The target board includes a magnetic rubber sheet having a rectangular shape and containing iron, the two sheets of cotton flannel being attached to both surfaces of the magnetic rubber sheet and having raisings on their outer surfaces, and an upper fitted piece attached to the upper end of the front surface of one of said two sheets of flannel. The holding pole includes a hollow for holding one end of the target board, a slit formed along the entire length of the holding pole to pass through the inner and outer circumferential surfaces of the holding pole, and holes for allowing a hanging string to be fastened to the holding pole. The two closure members are each provided with an inserting recess into which one end of the holding pole is inserted.

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Gas Sensing Characteristics of WO3 (III)

Details: Category: Tungsten Information; Published on Thursday, 05 February 2015 18:04; Written by cq; Hits: 1521

(3) Gas sensing characteristics to organic gases ( acetone, ethanol etc.)

The morphology of the materials could be designed in the stage of hydrothermal reaction. Some scholars employed a novel hydrothermal process to synthesize plateshaped WO3 nanostructures. The addition of structure-directing agent p-nitrobenzoic acid results in the formation of WO3 nanoplates. The pH value in the reaction system may cause the nano-plate etched partially so that some nanoplates become incomplete with rough edge regions or a hole in the middle. The voltage levels up quickly in presence of ethanol or acetone and restores soon after removing the gases. It demonstrates that the as-prepared WO3 nanoplates have good sensitivity and reversibility to ethanol or acetone. However, the working temperatures are relatively high (340℃ and 370℃) . These temperature values bring lot of difficulties for the actual application of WO3-based gas sensors.

Besides, Another scholars have successfully synthesized large-scale Co-doped h-WO3 nanorods by a facile hydrothermal method with Na2WO4·2H2O and Co(NO3)2·6H2O. They found the nanorods grown vertically from the center towards two opposite directions and had a uniform thickness of about 10 μm. Sensing responses of samples towards a series of typical organic solvents and fuels had been investigate. It is well known that WO3 is less sensitive to hydrocarbons. Whereas, it is noticed that Co-doped WO3 nanostructure is highly sensitive to these flammable organic gases. This illustrates that dopant endows WO3 with better sensing performance towards hydrocarbon gases.

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