Compare APT and H2WO4 as raw material producing tungsten trioxide (WO3-X) photocatalyst found that different performance WO3-X photocatalyst produce by different materials. After further studies found that different performance WO3-X photocatalyst obtained from different producing methods.

Using solid phase method and the H2WO4 as raw material the production of WO3-X photocatalyst are monoclinic.  Photocatalytic performance influence by temperature was very little. And there have been sixty thousand phase and orthorhombic in the WO3-X which is produced by hydrothermal synthesis method. Oxygen index is 2.50 and photocatalytic performance has been greatly improved. The product of hydrothermal synthesis method 24 hours reaction has highest rate of photolysis. At 365nm ultraviolet light, oxygen production rate arrive at 140umol / L / h O2. However, hydrothermal method, with the reaction temperature, the raw material has undergone transformation which is orthogonal WO3-X • 0.33H2O → sixty thousand WO3-X → monoclinic WO3-X's. Photocatalytic performance will continue to reduce when the WO3-X sixty phase content continue to reduce.

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The tungsten crucible owns a particularly high density and purity. By correctly filling the mold used for the crucible and carefully controlling the temperature distribution during sintering, to achieve uniform wall and base thicknesses - an important prerequisite in achieving the high level of creep resistance that characterizes our crucibles.

During sapphire production, Al2O3 - the compound that is to become the future single crystal - is melted in molybdenum and tungsten crucibles. It is in the process that pressed-sintered crucibles show their strengths to best effect. They are repeatedly heated to more than 2 000 °C (3632 °F) and then cooled down again. This process, which would cause fissures and distortions in other materials, is not a problem for PLANSEE products. 

If the surface of the crucible is too rough, the sapphire cannot be released or can only be partially released from the wall of the crucible, which results in cracks and faults in the crystal. Not only that: The crucible itself is also damaged in the process and has to be reworked or replaced earlier than planned.

Our pressed-sintered crucibles made of tungsten have a surface roughness of less than 0.8 µm. The sapphire can be extracted from the crucible without difficulty and without damaging the surface of the crucible. For the sapphire producers, this results in fewer complexes and expensive reworking of the surface of the crucible. The cycles run smoothly and deliver high-quality ingots. And there's another advantage: The smooth surface is less susceptible to corrosion caused by the aggressive melted sapphire. This increases the service life of the reusable tungsten crucibles.

 

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Since the price state of tungsten trioxide changes largely, and it is difficult to determine the oxygen content, structure phase changeable and electrical properties and complex reasons, the photocatalytic properties of different crystalline WO3-X has not be determined. After a lot of research found different materials and different producing method synthesized different WO3-X and the structure and photocatalytic performance are different. Firstly, using solid phase method to sinter WO3-X photocatalyst and APT is raw material. It is mainly monoclinic phase. When the treatment temperature is 600 ℃, the processing time is four hours, there have been sixty thousand phase WO3-X, oxygen index of 2.44, water photolysis rate is the highest. At 365nm ultraviolet light, oxygen production rate is 148.8umol / L / h O2. Then compare using H2WO4 as raw materials by solid phase method to sintering WO3-X photocatalyst. Using this method producing WO3-X photocatalyst is monoclinic phase, but temperature had little effect on the photocatalytic decomposition of water properties.

Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
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Tungsten crucible’s general use specification requires thickness is between 6 mm-10 mm, is also a thin-walled crucible. Because of the brittleness of tungsten, so its process is only by a simple hand-shaping, and can not be lathe shaping. Thus, the thickness after pressing determines the thickness of the product. Therefore, the choice of latex coat diameter should be larger than mandrel of 6 mm-10 mm.

If the selected latex coat is too large, it will lead to the gap between mandrel and latex coat is too big, because the tungsten powder particles are relatively large and heavy, while the thickness of the latex coat itself is also between 2 mm-4 mm, which will lead to excessive loading weight and thick walls. The chosen of seal size is: 4 mm smaller than the inner diameter of mandrel and a thickness of 8 mm-10 mm. If you calculate sintering shrinkage by a rate of 12% -16%, the wall thickness after pressing should be around 8 mm-12 mm.

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
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