Originally Posted by Skippy722
Originally Posted by spasm3
Originally Posted by jayjr1105
If it's a less expensive metal and it can withstand more heat, why not use them?
They are close, but the melting point of iridium( 4435F) is higher than ruthenium (4233f).
Why use ruthenium, if iridium has a higher melting point?
Iridium is $1400 and oz and ruthenium is $250 and oz. I'm sure the profit margin is much better if they can sell the ruthenium plugs at the iridium prices.
If the plugs are easy to get to and you don't mind changing them, sure use non- precious plugs every 30k. But if you have a difficult to change vehicle i'd use iridium, I don't get the advantage of ruthenium other than its a higher profit margin for the company.
MolaKule posted in another thread that ruthenium is more resistant to erosion. A spark plug also won't get anywhere near being that hot, so the slight difference won't mean much between the 2.
"The more exotic refractory metal tips simply give you more tip life and less gap growth because they erode less during the 'plasma' phase of the spark.
As of right now, Ruthenium seems to have the lowest erosion rate of all of the refractory metal center electrode tips.
Next year, another more exotic metal or metal compound may be found that surpasses Ruthenium.
"
What people forget to focus on also, is what's on the ground electrode end of the spark plug. It's not ruthenium, it's platinum attached to it, in both its ground electrode configuration (projected square electrode and the "twin tip" type).
Originally Posted by spasm3
Originally Posted by slacktide_bitog
Tungsten's melting point is over 10 thousand degrees, so why don't we have tungsten spark plugs?
Is ruthenium harder? Or does it have some other property that would make it last longer despite the lower melting point?
Do they last longer? Laser iridums are 100k.
But Irdium-IX is shorter. On my car, I have to replace them every 20,000 miles.
Laser iridium has a platinum wear disc on the ground electrode, which the Iridium-IX does not have.