Solid lubricants

Solid lubricants are materials, which in solid phase reduce friction between surfaces sliding against each other, without the need for a liquid medium.

They are able to provide improved lubrication at higher temperatures compared to traditional oil-based lubricants. Low-friction properties of dry lubricants are attributed to their layered structure on the molecular level with weak bonding between layers. Such layers are able to slide relative to each other with minimal applied force, therefore giving them their low friction properties. However, a layered crystal structure alone is not necessarily sufficient for lubrication. There are some solids with non-lamellar structures that function well as dry lubricants in certain applications such as polytetrafluroethylene(PTFE or Teflon®).

The most commonly used solid lubricants are:
• Graphite. (C)
• Molybdenum disulfide. (MoS2)
Hexagonal Boron Nitride. (hBN).
Polytetrafluroethylene (PTFE or Teflon ®)

Solid lubricants in oils (dispersions)

The solid lubricants, when correctly formulated and dispersed, are a unique combination of lubricants that have exceptional properties. Although these can be approached individually by conventional chemical additives, the balance of properties required in many heavy duty industrial lubricants as well as high performance automotive oils and greases, can only be obtained with a perfect blend of colloidal solid lubricants.

Features of colloidal Solid Lubricants:

  • They reduce friction:
    • Reduced energy costs
    • Fuel savings
    • Reduced running temperatures
    • Increased power availability
    • Smooth running
    • No seizure
  • They increase load capacity:
    • Reliable and smoother running-in
    • Shorter running-in procedures
  • They absorb shocks and prevent wear through vibration
    • Ideal for heavy duty conditions
    • Longer life for components
    • Reduced maintenance cost
    • Greater operating time
  • They are not consumed in use
    • Longer drain life
  • They can operate in dry conditions
    • Machinery insurance against lubricant supply failure
    • Wide temperature range

Particle size

Particle size is important because in a solid/liquid system, the settling rate is proportional to the square of the diameter of the particle. If the particle size is halved, its rate of sediment action is reduced by a factor of four. Particle size control is therefore vital.

Colloidal dispersions are sufficiently fine to pass through automotive filters without clogging or build-up. The particles in our dispersions are smaller than blood cells and invisible to the naked eye.

Stability

Regardless of particle size, even the finest dispersion will settle if it is not stable. When dispersions are not stable they will flocculate, that is the fine particles will agglomerate into large particles, and quickly settle. This can be prevented by coating the primary particles with a layer of stabiliser that avoids coagulation.

A properly designed stabiliser is an essential partner to a fine particle size dispersion. The colloidal dispersions have long shelf life stability with little or no settling they might require only mild agitation to disperse the settled solids.

Compatibility

Not only must the stabiliser work in these products, but it must also continue to be effective when blended with lubricating components likely to be used by the customer. Moreover, our aftermarket additives must absolutely be compatible with all type of oils available on the market. For this we continuously carry out stability tests on the latest generations of engine and transmission oils. This compatibility should be maintained under actual operating conditions such as high temperatures and moisture contamination. Room temperature stability is not enough. The efficiency of the stabilizer results of its compatibility with the finished lubricant, base oil, and soluble additives under operating conditions.

XENUM applications of colloidal solid lubricants

Ceramic composite

Xenum developed the concept of Ceramic Composite Technology: ceramic particles or hexagonal Boron Nitride (hBN) dispersed in ester oil.

The combination of the exceptional lubrication properties of the hBN and Ester oils, provides a product that is unequalled in performance. The polar properties of the Ester oils will not only improve the lubrication through a strong oil film, but will also keep the micro hBN particles in suspension.

Ceramic composite additives, used in the VRX 500 and our Ceramic oils, reduce friction and wear spectacularly.

This will generate more power, lower fuel consumption, less pollution, fewer CO2 emissions and less wear. This technology is very suitable for high performance and racing applications as well as for industrial machinery.

The Hexagonal Boron Nitride (hBN) particles used in Xenum lubricants, are extremely small (0,25µ), and will neither clog filters nor coagulate.

Used in:

Cerflon®

Cerflon® is a ceramic reinforced fluoropolymer (PTFE) that occurs when Boron Nitride, which is stronger and tougher, is introduced into the matrix of a fluoropolymer (PTFE) thereby ‘reinforcing’ the polymer.

This additive significantly increases the durability or wear properties. Cerflon® is a patented technology.
Used in:

Carbon-graphite

Carbon-Graphite technology is a dispersion of micro graphite particles in oil.

These particles are very small (1µ) and consist of an infinitely number of hexagonal carbon crystals comparable to diamond. Our Graphite based motor oils offer an economic alternative to our top tier Ceramic oils.

Used in:


Solid Lubricant Technology thumbnail
ProductCoefficient of frictionTemperature range
Graphite0.11 to 0.2450°C - 538°C
MoS20.10 to 0.15 343°C - 399°C
PTFE0.06 to 0.10260°C - 302°C
Cerflon ® 0.06 to 0.09260°C - 302°C
Boron Nitride 0.08 to 0.122.200°C - 2.760°C