A Method For Extracting Sapphire Ingots From Tungsten Crucibles

Nov 29, 2019

Tungsten crucible is the core component of sapphire monocrystalline growth furnace, which is widely used in sapphire growth crystal industry. The waist of the tungsten crucible will deform under long working at high temperature, because the sapphire ingots in the tungsten crucible are in a "pear-shaped" state, with a small top and a large bottom. When the waist of the crucible is deformed to a certain extent, the sapphire ingots can easily get stuck in the deformed part of the tungsten crucible and cannot be safely removed. In addition, the tungsten crucible and crystal sapphire ingot are very high hardness and has bigger brittleness material, very prone to brittle crack when squeezed, therefore, are stuck in the extraction of tungsten crucible sapphire ingot by hydrogen peroxide preheating, hydrogen peroxide solution immerse inside crucible, take tungsten crucible was stuck inside ingot, tungsten crucible subsequent processing these four steps.

Firstly, the hydrogen peroxide should be preheated. The industrial pure hydrogen peroxide or analytical pure hydrogen peroxide should be poured into the beaker and placed on the electric furnace for heating to 50-70℃. A tungsten crucible is then continuously filled with a heated hydrogen peroxide solution, in which the ingot is completely immersed where it is stuck. After 6-8 hours, if the hydrogen peroxide is greenish-yellow and no bubbles appear on the surface of the liquid, the solution can be poured out, and then the hydrogen peroxide is poured into the tungsten crucible again for 3-4 times. After pouring, tie the stuck ingots in the crucible with a copper braid, and remove the stuck ingots with the help of a moving stacker and a sling. After taking out the stuck ingots to use the method of processing the inner wall of the tungsten crucible processing, in order to improve the deformation of the tungsten crucible, to prevent the ingots were stuck again.

In addition to the above methods, the most commonly used extraction method is mechanical grinding. The deformed parts of the tungsten crucible were manually ground using alloy or ceramic tools to enlarge the inner diameter of the waist of the tungsten crucible, and finally the stuck ingots were removed. However, because this method is manual control, it requires more time and effort. If a tungsten crucible is struck to remove the stuck ingots, a lot of waste will be caused.