Tungsten bar with impurities is used to procedure bulb filaments or electron tube filaments, which are guaranteed to have remarkable resistance to high temperature.
Grade of tungsten bar:
In reference to different chemical components and applying requirement, the grades of products are divided into four categories:W1, W2 ,W3,W4.
Appearance of tungsten bar:
The appearance of tungsten bar turns to be metallically gray or dark gray. Hygroscopy is not allowed on the appearance of W1 ,W2, and W3 tungsten bars.
Surface State of tungsten bar:
Any oxidation, contamination, and severe excessive fusion, bubbling, delamination, or crack is not allowed for product W1. Camber should be no more than 10mm. Any excessive fusion, bubble, delamination, crack, surface bulky crystallization or severe oxidation &contamination are not allowed for products W2 and W3. The length of the spalls should not be more than 8mm, width no more than 3mm, depth no more than 1mm; The diameter of mechanical pitting should not be more than 1mm, depth no more than 0.5mm; Camber should be no more than 4mm.
Any oxidation or contamination is not allowed for product w4.
The cartridge of the vertical sintering part should be cut off, and the section is not allowed to be loose or intermingled.
The density for W2, W3 tungsten bars is more than 17.5g/cm3.
Measured data for the section grain size of W2, W3 can be provided. If the buyer has any other special demand, it can be discussed on the base of mutual negotiation.
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