Lubricant Additives

240 Lubricant Additives: Chemistry and Applications

clamping pot, while the fourth ball is made to rotate against them. Test lubricant is added

in the test pot, covering the contact area of the test balls. During a test, wear scars are

formed on the surfaces of the three stationary balls. The diameter of the scars depends on

the load, speed, temperature, duration of run, and type of lubricant. The Four-Ball EP tes-

ter runs at a fi xed speed of 1770 ± 60 rpm and has no provision for lubricant temperature

control. A microscope is used to measure the wear scars. Two of the standard tests run

on the Four-Ball machine are Mean-Hertz Load and Load-Wear Index. ASTM D 2596

covers the detailed calculation procedure of Load-Wear Index for greases and D-2783

Boundary Elastohydrodynamic Hydrodynamic

Machine ways

heavily loaded

gears

Gears rolling

element

bearings

Journal bearings

Friction

Viscosity × speed / load

1. Viscosity Viscosity and viscosity index

Active antiwear and EP additives

Controlling lubricant factors

2. Pressure-viscosity coefficient

FIGURE 8.2 Lubrication regimes.

FIGURE 8.3 Ashless antiwear additives: availability, applicability, selection, and future needs.

• Availability
  
  
  • Novel chemistries are available (S/P/N/B)
  
  
  • Protecting film can be formed from
    low-shear, nonmetallic species
  
  
  • Process development, registration, and
    commercialization plan pending on
    market demand and timing
  
  
  
  


• Applicability
  
  
  • Bench tests only serve as indicators
  
  
  • Balance of performance is key
  
  
  
  


• Selection
  
  
  • Identifying critical tests first
  
  
  • Seeking combinations of additives
  
  
  • Using QSAR analysis
  
  
  
  

Four-Ball Wear/EP

HFRR & Plint

Multispecimen

Optimol SRV

Pin-on-V-block

Seq IVA and IIIG

JAMA chain wear

FZG and FE8

M11 EGR

35VQ25 pump

OM 602/TU 3M

L37/L42

Engine and industrial oils

Reduced exhaust emissions

Improved stability

High temperature oxidation/nitration

Oxidation resistance/hydrolytic stability

Improved compatibility and cleanliness

Improved surface fatigue-wear protection

Pitting and micropitting

Antiscuffing

Lo w friction

Fuel economy and energy conservation

Improved durability

Extended drain

Fill for life

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