Electrodes in high intensity discharge lamps (HID lamps) usually consist of a cathode, an anode and the support rod (stem). Depending on the type of lamp, the electrodes may be complex molded products or simple pins.

 

If a voltage is applied at the anode and cathode then a light-emitting arc is generated. During operation, the tips of the electrodes must withstand temperatures of 1 800 to 3 200 °C. They conduct the emitted heat to the electrode body and the support rods (stems).

 

Tungsten is the only metal that can meet the high physical and mechanical requirements. Tungsten has the highest melting point of all metals, a low vapor pressure, low thermal expansion, good thermal conductivity and a low electron work function. 

 

Our many materials engineers use our in-house powder metallurgical manufacturing procedures to prepare tungsten optimally for use in cathodes, anodes or support rods (stems). With special alloy additives, we improve the high-temperature dimensional stability, electron work function, formability, machinability and thermal conductivity of the material.

 

For cathodes, we supply thorium, aluminium-potassium silicate (AKS) or lanthanum oxide-doped tungsten. A new addition to the range: WLZ, a tungsten material doped with lanthanum and zirconium oxide.WLZ is the non-radioactive alternative to thorium-doped materials.

 

Anodes have to withstand extreme thermal loads. PLANSEE can supply special potassium-doped tungsten materials for this type of application: WVM and WVMW. These materials benefit from a particularly high level of thermal stability and are characterized by excellent arc erosion resistance.

 

Support rods (stems) are exposed to severe mechanical shocks. PLANSEE supplies the tungsten material WL-S which is doped with lanthanum oxide. WL-S is exceptionally resistant to breakage even after high-temperature processing.  

 

Our materials for tungsten electrodes at a glance. Naturally, we would be delighted to help you choose the optimum material for your application.

 

• Cathodes: WT20, WVMWT, WLZ, porous tungsten, WL10, pure tungsten
• Anodes: WVM, WVMW, S-WVMW, pure tungsten 
• Support rods (stems): WVM, WL-S

We handle every stage in the manufacture of our products for the lighting industry in-house. From the raw materials through to the finished product. This ensures that you benefit from high-quality at all times.

 

Raw material (oxide)	Reduction	Metal powder	Mixing	Pressing	Sintering	Forming	Heat treatment	Machining Joining Coating	Quality assurance