Carbonizing (metalworking)
Carbonization or coaling refers to the covering of the surface of electrodes made of sheet metal or wire mesh of electron tubes with a thin, blackening carbon coating .
The creation of this layer can be done by
- Precipitation of soot from flames ,
- Application of finely divided carbon mixed with a binding agent (e.g. Aquadag ) on the mostly roughened metal substrate with subsequent heating under vacuum to 700–950 ° C, advantageous for substrates made of nickel ,
- thermal decomposition of hydrocarbons
can be achieved.
The surfaces treated in this way have an increased radiation of the thermal energy introduced by the anode power loss . Are carbonized u. A. Anodes , grids or cooling wings in amplifier or small transmitter tubes.
Carbonized surfaces are not very smudge-proof and costly to degas . From the 1940s onwards, anodes treated in this way have been almost completely replaced by P2 iron , a surface roughened by an aluminum-iron reaction.
literature
- Werner Espe: Materials science of high vacuum technology . 1: Metals and metallically conductive materials. VEB Deutscher Verlag der Wissenschaften, Berlin 1957.