Inert Mat Reinforced Massive Lead Dioxide Anode
This type of anode has been made and used successfully.
The anode is plated onto a flat piece of Valve metal with a piece of inert reinforcing attached to the metal. The back and edges of the metal is covered with plastic tape or some such to stop Lead Dioxide from depositing on it. The anode is grown on the Valve metal and will incorporate the inert reinforcing.
'Scotch pads' used for cleaning domestic pots is a good material to use for the inert reinforcing. The tank pH must not be very low at the start of deposition as the metal may passivate before plating can commence. Tantalum is better than Ti in this respect, GB 850,380 or US 2,872,405 or US 2,994,649 (SS used). An alternative would be to use an Alkali bath (Lead Tartrate) to first put on a layer of Alpha LD. The Alkali baths will not anodize the Valve metal . In fact it may be possible to use an attackable temporary substrate such as Nickle or Iron if the Tartrate bath is used (US US 2,846,378) or a pH controlled Nitrate bath.
Anodes are inclined to bend as they plate when made this way. It may be advantageous to use a piece of Ti that is curved (or a half pipe) and coat the inside surface of this to help with the compressive stress associated with the Beta LD.
Since Alpha LD mainly deposits when high current density's are used (70mA/cm squared) and Beta at 40mA or below. It may be possible to alternatively plate Beta/Alpha/Beta/Alpha/Beta, by simply changing current density's. This is a guess. Alpha created this way, (as opposed to using an Alkaline bath) may not have the same strain associated with it as discussed in US 4,O64,035 below.
An anode was made by Hashashan. It was grown on Ti using 'Scotch Brite' as the reinforcing in a Lead Nitrate bath. It was grown slowly over a few days. Silver paint was used as the connection and was tested in a (Per)Chlorate cell.
There is an account of some massive anodes here.
US 4,064,035 gives an account of using Alpha + Beta layers to eliminate stress in the anode to stop it from bending as it is made. Graphite (or Iron or SS) can be used for the temporary substrate. It should be noted that a Beta layer should be deposited first and last so that when the anode goes into service (substrate removed) then there will be Beta exposed to the electrolyte as Beta is more resistant to corrosion and that Alpha. When using attackable substrates you must start with a bath that has not got too low a pH or alternatively use an Alkali bath for to start the anode off.
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