Heat shields, heating elements and vacuum furnace supports are made of tungsten foil. The foil is thin and is ideal for embedding in laminates, other metals and glass; it is made of mental tungsten and can be used in high temperature vacuum furnaces, coatings, electronic and semiconductor components.
How to produce the thin foil?
Compared with the coating deposition method, the rolling method is more suitable for the production of tungsten foil, mainly due to the advantages of higher hardness, surface finish and mechanical strength, especially the density can be close to the theoretical density of tungsten. However, the working efficiency of the commonly used four-high rolling mill in industry is extremely low, and the production equipment is easily damaged due to the long-term high rolling tonnage. In order to solve the above technical problems, the researchers with the patent document serial number 17017104 proposed a rolling method of high-precision W foil. The specific steps are:
1)Cut the tungsten plate (thickness 0.09mm~0.11mm) into the same size of plate; 2) Place the nickel sheet as a welding sheet between the tungsten sheets obtained in the adjacent step 1), and use a spot welding machine for spot welding to obtain a welded tungsten sheet; the number of tungsten sheets is 2 to 4 pieces, and the nickel sheet is placed on one end of the tungsten plate along the length direction, and the width direction of the nickel plate is consistent with the length direction of the tungsten plate; 3)Perform multi-pass rolling on the welded tungsten plate obtained in step 2) to obtain a rolled foil; the tonnage of the rolling equipment used in the multi-pass rolling is 60t-120t, and the roll crown is 0.04mm-0.06 mm; when the total processing rate of multi-pass rolling exceeds 40%, the rolled welded tungsten sheet is annealed; the thickness of the rolled foil is 0.04mm to 0.08mm; 4) Cut off the welded end of the rolled foil obtained in step 3), and then separate the layers in the rolled foil to obtain a foil; the thickness of the foil is 0.018mm to 0.023mm, and the thickness tolerance ± 0.0015mm, width 175mm ~ 180mm.
The advantage of this rolling technology is that spot welding the tungsten plate of the same size with the nickel plate as the welding piece not only ensures the melting of the nickel plate to the welding of the tungsten plate, but also avoids the brittleness of the tungsten plate, which is beneficial to the later stage. The first rolling was carried out smoothly, and 2 to 4 pieces of foil with uniform size were produced at one time, which solved the problem of low efficiency of single rolling and greatly improved the production efficiency; at the same time, small-tonnage rolling equipment was used to carry out multi-pass rolling makes the rolled W foil uniform in thickness and bright in surface, which effectively improves the precision of W foil.
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