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Slippery Customer: A Greener Antiwear Additive For Engine Oils

Date:
July 29, 2008
Source:
National Institute of Standards and Technology
Summary:
Titanium, a protean element with applications from pigments to aerospace alloys, could get a new role as an environmentally friendly additive for automotive oil.
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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.
Credit: NIST

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 (NIST).

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 phosphorus 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.


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The above post is reprinted from materials provided by National Institute of Standards and Technology. Note: Materials may be edited for content and length.


Journal Reference:

  1. Guevremont et al. Enhancement of Engine Oil Wear and Friction Control Performance through Titanium Additive Chemistry. Tribology Transactions, 2008; 51 (3): 324 DOI: 10.1080/10402000701772595

Cite This Page:

National Institute of Standards and Technology. "Slippery Customer: A Greener Antiwear Additive For Engine Oils." ScienceDaily. ScienceDaily, 29 July 2008. <www.sciencedaily.com/releases/2008/07/080723143548.htm>.
National Institute of Standards and Technology. (2008, July 29). Slippery Customer: A Greener Antiwear Additive For Engine Oils. ScienceDaily. Retrieved August 29, 2015 from www.sciencedaily.com/releases/2008/07/080723143548.htm
National Institute of Standards and Technology. "Slippery Customer: A Greener Antiwear Additive For Engine Oils." ScienceDaily. www.sciencedaily.com/releases/2008/07/080723143548.htm (accessed August 29, 2015).

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