Titanium could get eco-friendly role as antiwear additive for engine ...

Tag : Titanium Alloys
In a recent paper, the researchers established that a titaniumcompound added to engine oil creates a wear-resistant nanoscalelayer bound to the surface of vulnerable engine parts, making it acredible substitute for older compounds that do not coexist wellwith antipollution equipment.

Modern engine lubricating oil is a complex, highly engineeredmixture, up to 20 percent of which may be special additives toenhance properties such as viscosity and stability and to reducesludge formation and engine wear, according to Afton specialists.

For years, antiwear additives for high-performance oils have beenphosphorous compounds, particularly ZDDP, that work by forming apolyphosphate film on engine parts that reduces wear.

Unfortunately, phosphorus is a chemical poison for automobilecatalytic converters, reducing their effectiveness and life span,so industry chemists have been searching for ways to replace orreduce the use of ZDDP.

It's not a simple problem because the additive has several usefulfunctions in addition to wear resistance.

Titanium is one candidate replacement.

Mechanical tests of an organic titanium compound at Aftondemonstrated that it provided superior wear resistance when addedto a fully formulated engine oil, suggesting that oil chemistscould use less ZDDP.

Just how the titanium compound works was an open question, however.

Surface analysis tests could detect titanium in the wear tracks oftest surfaces but not with enough sensitivity to determine itschemical nature-and whether, for example, it was just lying thereor bound to the metal surface.

To resolve the issue, the researchers turned to NIST's soft X-raybeamline at the National Synchrotron Light Source (NSLS) inBrookhaven, New York.

The NIST beamline instruments use low-energy ("soft") X-rays thatcan be precisely tuned to specific elements to measure chemicalbonds both at the surface of a sample and deeper into the bulk ofthe material.

The measurements revealed that the antiwear enhancement comes fromtitanium chemically bound into the metal structure of the enginesurface, forming a hard oxide, iron titanate.

Comparing the test data to that of several possible compounds, theresearch team was able to identify the specific oxide.

While considerably more work remains to be done, the resultssuggest that titanium could play an important role in futurelow-phosphorus lubricating oils.
--- ANI