Tensile strength
15,000 psi
Compressive strength
100,000 psi
Brinell hardness
520
Density
7.0 grams per cubic centimeter
Melting point
2300 degrees F
Coefficient of
expansion from 32
to 212 degrees F
0.00000733 centimeter per degree F
2.1.2
Mixed Metal Oxide Anodes
Mixed metal oxide anodes shall be of the size indicated and shall conform
to the following requirements.
2.1.2.1
Conductive Material
The electrically conductive coating shall contain a mixture consisting
primarily of iridium, tantalum, and titanium oxides. The average
composition is generally a 50/50 atomic percent mixture of iridium and
titanium oxides, with a small amount of tantalum. The resistivity, as
tested by the manufacturer, shall be no more than 0.002 ohm-centimeter, and
the bond strength shall be greater than 50 MPa 7.25 ksi to guarantee the
current capacity life and the quality of the conductive ceramic coating.
The adhesion or bond strength shall be determined by epoxy bonding a 2.54
mm 0.1 inch diameter stud to the ceramic coating and measuring the load to
failure (about 70 MPa 10.15 ksi) of either the epoxy or the interface
between the coating and the substrate. The anode must be inert and the
electrically conductive ceramic coating dimensionally stable. The ceramic
coated anode shall be capable of sustaining a current density of 100 ampere
per square meter 10.764 square feet in an oxygen generating electrolyte at
66 degrees C 150 degrees F for 20 years, to ensure the current capacity
life. An accelerated current capacity life test shall be performed by the
manufacturer on every lot of anode wire used to construct the anode as
described. The mixed metal oxide coating shall be applied to the wire
anode by a firm that is regularly engaged in and has a minimum 5 years
experience in manufacturing and applying mixed metal oxide coating to
titanium anode substrates. The mixed metal oxide shall be sintered to the
titanium surface to remain tightly bound to the surface when bent 180
degrees onto itself.
2.1.2.2
Anode Life Test
The anode wire material shall sustain current densities of 100 ampere per
square meter 10.764 square feet in an oxygen generating electrolyte for 20
years. The manufacturer shall certify that a representative sample taken
from the same lot used to construct the anode, has been tested and meets
the following criteria. The test cell sustains a current density of 10,000
ampere per square meter 10.764 square feet in a 15 weight percent sulfuric
acid electrolyte at 66 degrees C 150 degrees F without an increase in anode
to cathode potential of more than 1 volt. The cell containing the anode
shall be powered with a constant current power supply for the 30 day test
period. The representative sample shall be 125 mm 5 inch in length taken
from the lot of wire that is to be used for the anode.
2.1.2.3
Anode Connecting Cables
The connection between the anode rod or ribbon and the lead wire shall be
made with a solid crimp couple with solder. The connection shall be sealed
in cast epoxy.
SECTION 13111A
Page 11
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