Slippery Customer: A Greener Antiwear Additive for Engine Oils

Jul 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: Nature inspires a greener way to make colorful plastics

add to favorites email to friend print save as pdf

Related Stories

Hoverbike drone project for air transport takes off

3 hours ago

What happens when you cross a helicopter with a motorbike? The crew at Malloy Aeronautics has been focused on a viable answer and has launched a crowdfunding campaign to support its Hoverbike project, "The ...

Study indicates large raptors in Africa used for bushmeat

3 hours ago

Bushmeat, the use of native animal species for food or commercial food sale, has been heavily documented to be a significant factor in the decline of many species of primates and other mammals. However, a new study indicates ...

'Shocking' underground water loss in US drought

3 hours ago

A major drought across the western United States has sapped underground water resources, posing a greater threat to the water supply than previously understood, scientists said Thursday.

Recommended for you

Nature inspires a greener way to make colorful plastics

8 hours ago

Long before humans figured out how to create colors, nature had already perfected the process—think stunning, bright butterfly wings of many different hues, for example. Now scientists are tapping into ...

New catalyst converts carbon dioxide to fuel

10 hours ago

Scientists from the University of Illinois at Chicago have synthesized a catalyst that improves their system for converting waste carbon dioxide into syngas, a precursor of gasoline and other energy-rich products, bringing ...

Bullet 'fingerprints' to help solve crimes

10 hours ago

Criminals don't just have to worry about their own fingerprints these days: because of a young forensic scientist at The University of Western Australia, they should also be very concerned about their bullets' ...

User comments : 0