Tantalum tube manufacturing process

Tantalum cannot be processed in the usual way that ordinary metals are processed. Generally, the initial process is forging and heat treatment, using hammering and stamping two ways to make plate blank or round small and medium-sized blank.

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Tantalum cannot be processed in the usual way that ordinary metals are processed. Generally, the initial process is forging and heat treatment, using hammering and stamping two ways to make plate blank or round small and medium-sized blank. Unlike ordinary metals, tantalum cannot be hot worked. If the recrystallization temperature of tantalum is over 1000 ~ C, excessive oxidation will occur even if the general protective coating is made. What's more serious is that if tantalum is exposed to such high temperature, not only excessive oxidation will occur on the surface of tantalum, but oxygen can also invade between atoms in the matrix, making tantalum brittle. Not only oxygen, but also nitrogen, carbon and hydrogen can make tantalum brittle. Due to the above reasons, tantalum is generally not hot worked. When hot working is necessary, protective coating or inert gas atmosphere shall be applied.

heat treatment

Due to the active reaction of tantalum with oxygen, it is necessary to avoid heat treatment in the atmosphere even in the presence of a little air. Therefore, almost all annealing is carried out in a high vacuum, and the furnace must be air tight. Generally, the heat treatment temperature of tantalum is 950 ~ 1300 ℃, and there is no phase transformation between tantalum and tantalum alloy in this temperature range. The heat treatment is only used for annealing, so the heating temperature and cooling rate are not important. In order to produce complete recrystallization, the heat treatment time is better.

Tantalum produced commercially is of high purity. The grains become very large by annealing. The size of crystal particles is determined by cold working, purity, temperature and process steps. Therefore, temperature control and process control are important means to determine the crystal size.

Tantalum, unlike many other metals, must be very clean before heat treatment. If it is not cleaned very clean, the surface contamination caused by hydrogen, oxygen, nitrogen and carbon will occur and become brittle (hardening) structure. Because hydrogen, oxygen, nitrogen and carbon are very active intrusive elements in the temperature range of tantalum annealing, once polluted by these elements, they can be removed except remelting.