The common causes of local overheating of tungsten wire mainly include the following points:
Uneven resistance:
During the production or use of tungsten wire, the resistance distribution may be uneven due to factors such as manufacturing process, material purity, and use environment.
When current passes through, the part with larger resistance will generate more heat, causing local overheating.
Sublimation and thinning of filament:
In applications such as incandescent lamps, tungsten wires will sublimate at high temperatures, that is, tungsten atoms are directly converted from the solid surface to gas.
After long-term use, tungsten wires will gradually become thinner, especially in some local areas. Due to the uneven sublimation rate, the resistance of these parts may increase, resulting in local overheating.
Hotspot effect:
The reduction of the diameter of the local section of tungsten wire, the aggregation of small bubbles generated by additives into large bubbles, and the chemical reaction of residual gas in the bulb with tungsten to cause the diameter of the local section to shrink, etc., may increase the resistance of the local section of tungsten wire, increase the temperature, and form hot spots.
Hot spots, in turn, will accelerate the evaporation of tungsten, further increase the resistance and temperature of the section, and thus accelerate the burning process of the tungsten wire.
Excessive current:
If the current passing through the tungsten wire exceeds its rated current, the overall heat generation of the tungsten wire will increase, especially in local areas with large resistance, which is more likely to cause overheating.
Poor heat dissipation:
The heat generated by the tungsten wire during operation needs to be dissipated through the heat dissipation system.
If the heat dissipation system is poor, such as heat sink blockage, fan failure, etc., the heat of the tungsten wire cannot be dissipated in time, resulting in local overheating.
To avoid local overheating of the tungsten wire, the following measures can be taken:
Optimize the manufacturing process and material selection of the tungsten wire to ensure uniform resistance distribution.
During use, pay attention to controlling the current size to avoid exceeding the rated current of the tungsten wire.
Strengthen the maintenance and care of the heat dissipation system to ensure that the heat can be dissipated in time.
For applications such as incandescent lamps, aging tungsten wires can be replaced regularly to reduce local overheating problems caused by sublimation.
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