Diamond Like Coatings...a term for high tech coatings that change the surface characteristics making them more durable and heat resistant. Bosch has been using them for several years in their HPFP's.
The new HPFP's run at such high pressures and temperatures that these coatings are being pushed to their limits. There has been a 50% increase in pressure in the last two years. Speculation, backed by good science, is that the coatings are struggling with these higher mechanical demands and chemical reactions created by the petroleum recipes.
Interesting stuff...good thing I have a good friend who can explain it...
Debbie and Savannah the Wonderdachsund
2009 Big Horn 3055RL
2006 Chevrolet Silverado 3500 Dually LTX with the Gold Standard LBZ Engine and Allison Transmission
2011 F350 Lariat SRW CC SB 4WD 6.7 Diesel POS Gone Bye Bye
Thanks for the information guys, we didn't cover this IIRC?? back in high school. Maybe it wasn't invented back then LOL. I really found the following paragraph interesting.
"Peer-reviewed research published in scholarly journals has established that the increases in lifetimes of articles coated with DLC that wear out because of abrasion can be described by the formula f = (g)µ, where g is a number that characterizes the type of DLC, the type of abrasion, the substrate material and ? is the thickness of the DLC coating in ?m. For "low-impact" abrasion (pistons in cylinders, impellers in pumps for sandy liquids, etc.), g for pure ta-C on 304 stainless steel is 66. This means that one-?m thickness (that is ~5% of the thickness of a human hair-end) would increase service lifetime for the article it coated from a week to over a year and two-?m thickness would increase it from a week to 85 years. These are measured values; though in the case of the 2 ?m coating the lifetime was extrapolated from the last time the sample was evaluated until the testing apparatus itself wore out.
There are environmental arguments that a sustainable economy ought to encourage articles not engineered to lower performance or to fail prematurely. This in turn will reduce the need to support greater production of units and their frequent replacement, which might provide an economic disincentive to manufacturers of such devices.
Currently there are about 100 outsource vendors of DLC coatings that are loaded with amounts of graphite and hydrogen and so give much lower g-numbers than 66 on the same substrates."
Houston errr Detroit we might have a problem.
Why does Ford keep stepping on the d&^k with their Diesel engines - they have not made a good since the 7.3! And yet the faithful keep buying them - go figure.
Perhaps not the most delicate way of phrasing it but I have wondered the same thing. I am not so quick to lump the 6.7 in the same pile as the 6.0 or 6.4 but because of the fact that these engines had such well documented problems, I would have expected FORD to really step up on the 6.7 and maybe go beyond what is even fair on the warranty claims just to make it right by their loyal customers. Not so much it appears. Yet the SD continues to lead in sales, even through the dark Oh no 6.0 days, I didnt understand it then, and its no clearer to me now (although even with the issues the 6.7 has, its launch has been 10X better than the previous engines were at this time). GM and Ram should be so lucky as to have a customer base that is as loyal to their brand as the FORD customers are to theirs.
2006 GMC 3500 CC 4X4 D/A
2013 Fuzion 342
2011 RZR Desert Tan
2012 Sea Doo GTX 155
2005 GMC 5500 CC 4X4 D/A
2012 Chevy 2500HD 4X4 6.0 3.73
Circumstantial (not actual) evidence that there may be a problem that Bosch and Ford did not foresee in the design, manufacturing and validation of the Bosch CP 4 series pumps:
The stuff below in plain english:
Relatively commonly used lubricant additives (PAOs)can degrade DLC coatings even under the modest temperature in the experiment (80C)
Oil additives interact with each other on DLCs in a way that is not well understood.
What would those tests show under 30,000psi and 150C?
“A partial degradation of the DLC coating in the HFRR tracks was observed for experiments performed in pure PAO, in PAO containing AP, and PAO containing didodecylamine.” P. 141
“As oil additives are usually used in packages in oil, the investigation of interactions between additives, as well as with the surface, is of the greatest interest. Tribological experiments
performed in PAO containing a mixture of b-TPPT, AP and friction modifiers already gave an insight their behavior. On steel, the friction behavior showed a delayed increase of the friction
coefficient followed by a slight continuous decrease until the end of the 1 hour-experiment.
On DLC, the friction coefficient decreased continuously during the HFRR tests. Addition of propanesulfonic acid to AP allowed observing a decrease of the friction coefficient during the
experiment. Polishing wear was not observed in the track, but scratches were visible. Octanethiol seemed to act as a friction modifier that decreased the friction coefficient with
time. Further tribological experiments and detailed chemical analyses would increase the understanding of additive interactions in the oil solution and at the DLC surface as combinations of additives often show synergetic or antagonistic effect. “
Investigation of the Interaction
between Diamond-Like Carbon
Coatings and Lubricant Additives
Environmental considerations are leading to the substitution of the widely used oil additive zinc dialkyl dithiophosphate (ZnDTP) by zinc-free, low-phosphorus and low-sulfur additives.
Many studies are now being performed to find a replacement for this highly effective additive, ZnDTP, with more environmentally friendly alternatives.
The increasing use of diamond-like carbon (DLC) coatings in oil-lubricated, mechanical systems has led to a great deal of interest in optimizing the interactions between lubricant additives and coatings.
In the present work, the ability of ashless anti-wear additives to form protective tribofilms on DLC and steel surfaces was investigated and compared to the reactions of ZnDTP.
Reciprocating sliding tests were performed under mild tribological conditions for steel/steel and DLC/DLC contacts to avoid wearing through the DLC coating. A temperature of 80°C was used for all oil-lubricated experiments as this is a standard operating temperature in engines and is too low for thermal decomposition of the additives. DLC self-mated tribocontacts were used to analyze the behavior of the additives in absence of iron.
A comparison of the friction behavior of ZnDTP with two ashless additives, a butylated triphenyl phosphorothionate (b-TPPT) and an amine phosphate (AP), indicated that the latter additive behaved in a different manner of the first two. b-TPPT showed the lowest friction coefficient for DLC/DLC contacts whereas the AP gave the lowest friction coefficient for steel sliding against steel. b-TPPT was selected as a typical metal-free additive and AP, as an additive that is both metal-free and sulfur-free.
Atomic force microscopy and environmental scanning electron microscopy were performed to analyze the rubbing tracks and compare the tribofilms formed from the different additives. ZnDTP and b-TPPT showed a similar tribological behavior for steel/steel and DLC/DLC contacts. Both built up pad-like structure on steel and a tribofilm was also formed on DLC coatings from the two additives, with a larger film thickness on steel. Ex-situ scratch tests
showed the weaker adhesion of the ZnDTP tribofilm built up on DLC compared with that built up on steel. No AP film was detected on DLC with AFM.
Chemical analyses of the tribofilms and thermal films built up by these three additives on steel and on DLC surfaces were performed with x-ray photoelectron spectroscopy and timeof-flight secondary ion mass spectrometry.
ZnDTP built up a tribofilm on steel made of a mixture of short chain poly(thio)phosphates with a higher presence of zinc phosphate on top
and iron phosphates further down. Short chain zinc poly(thio)phosphates were formed on DLC even in the absence of iron. Iron poly(thio)phosphates were also formed on steel from bTPPT,while the polymerization reaction of the additive was
more difficult on DLC in the absence of metallic counter-ions.
Polyphosphates were also present in the tribofilm built up from AP on steel. Although no tribofilm from AP was detected with AFM on DLC, products from tribochemical reactions were detected in the rubbing track. Mainly orthophosphates were detected and, additionally, significant concentrations of protonated alkylamines were detected.
Further experiments were performed to characterize the oxidation of sulfur-containing compounds on steel and DLC surfaces. Although it is well-known that thiols are oxidized by iron oxide, it was more surprising that the thiols were also oxidized on DLC. Dialkylamines were also found to react on DLC during tribological experiments.
* This post was
edited 02/07/12 11:41am by NewsW *