Slippery Customer: A Greener Antiwear Additive for Engine Oils

July 23, 2008
NIST materials scientists Cherno Jaye (r.) and Dan Fischer adjust a sample chamber for NIST's soft x-ray materials characterization beamline at the National Synchrotron Light Source. Image: NIST

(PhysOrg.com) -- Titanium, a protean element with applications from pigments to aerospace alloys, could get a new role as an environmentally friendly additive for automotive oil, thanks to work by materials scientists from Afton Chemical Corporation (Richmond, Va.) and the National Institute of Standards and Technology.

In a recent paper, the researchers established that a titanium compound added to engine oil creates a wear-resistant nanoscale layer bound to the surface of vulnerable engine parts, making it a credible substitute for older compounds that do not coexist well with antipollution equipment.

Modern engine lubricating oil is a complex, highly engineered mixture, up to 20 percent of which may be special additives to enhance properties such as viscosity and stability and to reduce sludge formation and engine wear, according to Afton specialists. For years antiwear additives for high-performance oils have been phosphorous compounds, particularly ZDDP (zinc dialkyldithiophosphate), that work by forming a polyphosphate film on engine parts that reduces wear.

Unfortunately phosphorus is a chemical poison for automobile catalytic converters, reducing their effectiveness and life span, so industry chemists have been searching for ways to replace or reduce the use of ZDDP. It’s not a simple problem because the additive has several useful functions in addition to wear resistance.

Titanium is one candidate replacement. Mechanical tests of an organic titanium compound at Afton demonstrated that it provided superior wear resistance when added to a fully formulated engine oil, suggesting that oil chemists could use less ZDDP. Just how the titanium compound works was an open question, however. Surface analysis tests could detect titanium in the wear tracks of test surfaces but not with enough sensitivity to determine its chemical nature—and whether, for example, it was just lying there or bound to the metal surface. To resolve the issue, the researchers turned to NIST’s soft X-ray beamline at the National Synchrotron Light Source (NSLS) in Brookhaven, N.Y.

The NIST beamline instruments use low-energy (“soft”) X-rays that can be precisely tuned to specific elements to measure chemical bonds both at the surface of a sample and deeper into the bulk of the material. Powered by the NSLS, the facility is at least 10 times more sensitive than commonly available instruments. The measurements revealed that the antiwear enhancement comes from titanium chemically bound into the metal structure of the engine surface, forming a hard oxide, iron titanate. Comparing the test data to that of several possible compounds, the research team was able to identify the specific oxide. While considerably more work remains to be done, the results suggest that titanium could play an important role in future low-phosphorus lubricating oils.

Citation: J.M. Guevremont, G.H. Guinther, D. Szemenyei, M.T. Devlin, T.-C. Jao, C. Jaye, J. Woicik and D.A. Fischer. Enhancement of engine oil wear and friction control performance through titanium additive chemistry. Tribology Transactions, Volume 51, 324-331, 2008.

Provided by NIST

Explore further: Russian Titanium

Related Stories

Russian Titanium

July 29, 2005

The situation regarding titanium is paradoxical. On the one hand, titanium is found in abundance in the natural environment: in terms of natural occurrence in the earth's crust, the element is the third among all metals, ...

Engineers use rust to build a solar-powered battery

February 26, 2016

The recent crash in oil prices notwithstanding, an economy based on fossil fuels seems unsustainable. Supplies of oil, coal and similar fuels are finite, and even if new sources are found, global warming must be considered. ...

Nanotech processing 'greener' than oil refining, study

October 5, 2005

Using a method for assessing the premiums that companies pay for insurance, a team of scientists and insurance experts have concluded that the manufacturing processes for five, near-market nanomaterials -- including quantum ...

Recommended for you

Cell fate regulation by LIN41 determined by binding location

January 20, 2017

Helge Großhans and his group at the Friedrich Miescher Institute for Biomedical Research (FMI) have elucidated the mode of action of the RNA-binding protein and stem cell factor LIN41. In an animal model, they showed that ...

Humans, not climate change, wiped out Australian megafauna

January 20, 2017

New evidence involving the ancient poop of some of the huge and astonishing creatures that once roamed Australia indicates the primary cause of their extinction around 45,000 years ago was likely a result of humans, not climate ...

Chemists cook up new nanomaterial and imaging method

January 20, 2017

A team of chemists led by Northwestern University's William Dichtel has cooked up something big: The scientists created an entirely new type of nanomaterial and watched it form in real time—a chemistry first.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.