The Metalthin twin-jet electropolisher was originally developed for producing high quality thin foils from radioactive materials. It is robust, compact, economical and easy to use. The Mk4 version incorporates the accumulated experience of many years of use in Universities, Industrial and Nuclear Research Centres.
It comprises three modules, the THINNING CELL, the UNIPUMP/DEWAR and the POWER SUPPLY.
The thinning cell (shown below) is contained in an electrolyte tank, machined from PVC and press fits into a solid PVC base that holds it upright. Drips of electrolyte are collected in a wide groove in the base. An additional tank is provided for washing the cell after use.
The electrolyte is circulated around the thinning cell by an impeller pump driven by a 12v dc motor. A stainless steel plate fitted to the base of the motor protects it from the corrosive electrolyte vapour. The pump motor cover is easily removed so that lead sheet may be placed around the motor to shield it from radiation, if required.
The photo-cell detector and light source plug into connectors at the ends of their respective leads. They are contained in screw-on stainless steel housings that push-fit into the thinning cell.
Perforation can be determined by eye when the detector housing is removed from the cell. This is necessary if composite specimens of 1mm discs pressed into 3mm discs are to be thinned and perforations occurring at the interface must therefore be ignored.
Thinning from one side only is achieved by placing a thin piece of glass over the disc. The glass is held in position during electropolishing by the screw-in portion of the disc holder.
Hazards associated with the use of inflammable/corrosive electrolytes and their disposal are reduced by the low volume of electrolyte required (100-220ml).
The thinning cell may be sited remotely from the power supply to protect it from the corrosive electrolytes.
If there is sufficient electrolyte (220ml) in the tank to completely submerge the cooling coil then cooling can be effected by circulating liquid nitrogen through the coil using the Unipump. The liquid nitrogen is contained in a Dewar flask with a lid that has been modified to accept the Unipump and keep it securely upright. The Unipump, Dewar and cooling coil are connected by Neoprene tubing. The operation of the Unipump is controlled from the Metalthin power supply.
If the minimum volume of electrolyte (100ml) is used then cooling is effected by standing the tank in a cooling bath. Coolant may be circulated through this bath from a Dewar using the Unipump.
This is completely separate from the thinning cell and cannot be operated until a key is inserted into the mains switch and turned. The normal supply voltage is 220v, 50Hz. Models that operate from 110v are supplied to order.
The functions available are:
a: control of the electrolyte flow rate
b: control of the coolant flow rate through the internal cooling coil
c: control of the dc current to the electrodes
c: illumination of the disc and detection of perforation followed by automatic cessation of electrolyte flow and dc current
d: option to continue jetting after perforation
e: option to apply a small reverse potential i.e. cathodic protection to the disc when perforation is detected.
f: option for an audible alarm to sound when perforation is detected
g: option to apply a dc ripple which may assist in retention of particles
POWER SUPPLY TO THINNING CELL CONNECTING CABLE
The various leads from the power supply to the thinning cell are gathered together to form a multi-cable contained in a flexible spiral wrap. The gaps between the spirals are sufficiently wide to allow accidental spills of electrolyte to be washed away.
The individual leads are easily replaced standard items.
The length of the standard connecting cable is approximately 1.5m. Different lengths will be supplied on request at no extra charge