Ford's answers to the NHTSA 6.7 Investigation
There was a request for a link to Ford's answer's to the NHTSA investigation posted on a previous thread, since closed. Here is the link: Ford's NHTSA Answers to the 6.7 investigation This PDF i...
Forum Discussion
Should explain how cavitation might be the culprit
First, ask if anyone has or seen a boat prop that is pitted and in some really
bad cases, crumbled?
That generally is from cavitation where the blade is moving so fast it creates
a negative pressure on the non-pressure side...AKA a vacuum
In most all fluids, there are micro or larger bubbles. Micro when at sea level
PSI's, but at lower PSI's or a vacuum, they expand greatly to suck off molecules
of prop material...even metal
H2O in the mix has this mechanism: there is a vapor pressure where it boils or
vaporizes below 212*F/100*C
That may NOT be as low a vacuum as the bubble (air).
Both will attack and remove molecules from whatever it is touching.
In this case DLC (diamond like carbon), which has a witches brew of organic
amines pre-attacking or concurrently attacking the DLC
The either the DLC lets loose a speck or a bubble (air or H2O) get underneath
a fissure in the DLC to lift it off.
I'm still not totally clear in my understanding of how H2O is reacting
and creating havoc in there, yet
There are many other ????'s that is yet to be discovered.
We 'think' stuff like is going on
First, ask if anyone has or seen a boat prop that is pitted and in some really
bad cases, crumbled?
That generally is from cavitation where the blade is moving so fast it creates
a negative pressure on the non-pressure side...AKA a vacuum
In most all fluids, there are micro or larger bubbles. Micro when at sea level
PSI's, but at lower PSI's or a vacuum, they expand greatly to suck off molecules
of prop material...even metal
H2O in the mix has this mechanism: there is a vapor pressure where it boils or
vaporizes below 212*F/100*C
That may NOT be as low a vacuum as the bubble (air).
Both will attack and remove molecules from whatever it is touching.
In this case DLC (diamond like carbon), which has a witches brew of organic
amines pre-attacking or concurrently attacking the DLC
The either the DLC lets loose a speck or a bubble (air or H2O) get underneath
a fissure in the DLC to lift it off.
I'm still not totally clear in my understanding of how H2O is reacting
and creating havoc in there, yet
There are many other ????'s that is yet to be discovered.
We 'think' stuff like is going on
