73
Is the tip in the
made of pure iridium?
We use a new iridium alloy developed at DENSO.
Iridium is characterized by a higher melting point than either nickel or platinum.
Therefore, it wears very well when subject to electrical discharge. However, at high
temperatures it oxidizes a little too much and so we are unable to use pure iridium for
spark plug electrodes.
DENSO studied many additives with a view to improving the corrosion resistance of
iridium and has now developed a new iridium alloy (the alloy of iridium and rhodium)
highly suitable for use in spark plug electrodes. Patents for this iridium alloy have been
secured in Japan, the United Kingdom, the United States, People’s Republic of China
and Republic of Korea. (Japan Patents 2877035, 3000955, 2921524. UK Patent
2302367. US Patents 6094000, 6262522, 5977695, 6078129. People’s Republic of
China Patent 961022841. Republic of Korea Patent 0292083.) The following
photographs compare the durability of the new iridium alloy and pure iridium when
used in an engine under the same conditions.
Melting point(
℃
)
Element
Oxidation resistance
3410
2610
2454
Tungsten (W)
Molybdenum (Mo)
Iridium (Ir)
1769
Platinum (Pt)
1453
Nickel (Nl)
1063
Gold (Au)
960
Silver (Ag)
Bad
Bad
Good
Better
Good
Better
Better
Part of the pure iridium material was shed and corroded. The new
DENSO iridium alloy showed no corrosion on the electrode and
mainfained good condition.
Test engine: 90 cc 4-cycle 1-cylinder Test conditions: Full
X
9000rpm
X
30h
New DENSO iridium alloy
Pure iridium
Содержание CAFITESSE 300
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