Ashless Antiwear and Extreme-Pressure Additives 237
activities are driving sulfur levels toward 10–50 wt ppm ranges. Subsequently, the petroleum indus-
try is favoring lower sulfur lubricants since sulfur is also known to poison the catalytic system
used for NOX reduction. Therefore, the use and development of nontraditional antiwear additives is
becoming more valuable.
A number of nonsulfur, nonphosphorus ashless antiwear additive technologies have been
reported in the literature [98–102]. Among these, high hydroxyl esters (HHE), dimer acids,
hydroxyamine esters, acid anhydrides, cyclic amides, and boron derivatives are recognized as
leading technologies. Graphite and polytetrafl uoroethylene (PTFE) possess excellent friction
reduction properties and indirectly contribute some antiwear/EP characteristics. However, both
materials need to be dispersed in the oil as they have very limited lubricant solubility, which ham-
pers their usefulness. Organic borates are considered as effective friction modifi ers, antioxidants,
and cleanliness agents. Recent studies indicate that some borates can be good antiwear additives.
Potassium borates have been used in gear oils for years, but these types of metallic borates are
outside the scope of this chapter. Esters are known to possess good lubricity properties. The prop-
erties can be further improved to offer antiwear characteristics through proper functionalization.
Several companies have marketable products in this area.
8.3 MANUFACTURE, MARKETING, AND ECONOMICS
All major additive suppliers produce ashless antiwear and EP additives that are available as
components and packages. Following is a list of major producers (arranged in alphabetical order).
Afton Corporation
Akzo Nobel
Atofi na Chemicals (former Elf Atochem NA and Pennwalt Corporation)
BASF
Chemtura (former Great Lakes Chemical’s Durad Division)
Ciba Specialty Chemicals
Chevron Corporation (Oronite Division)
Clariant
Dover Chemical (former Keil Chemical Division, Ferro)
Dow Chemical (former Angus Division)
Elco Corporation (Detrex)
FMC
Hampshire Chemical Corporation (former Evans Chemetics)
ICI America (Uniqema)
Infi neum International Limited
Lubrizol Corporation
Polartech
Rhein Chemie
Rhodia (former Albright & Wilson)
ZenecaAshless antiwear and EP additives are supplied in various chemistries, including single and
multiple blends formulated to maximize performance and minimize adverse effects (e.g., dropout
and corrosion). Product designations vary by chemical class and concentration. Many of them are
formulated into additive packages according to applications, such as passenger car engine oils,
heavy diesel engine oils, automotive transmission oils, automotive gear oils, hydraulic fl uids, and
others. Since the product offering information can be supplier-specifi c, it is recommended to contact
the suppliers directly or go to their corresponding Web site for further information.
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