From various current theoretical models, nanodiamonds and other nanomaterials are theoretically a unique class of materials with unique properties. Specifically applied to the field of lubrication, I can only say that the ideal is very fulfilling and the reality is very tangible.

In different occasions, I have been emphasizing that to my knowledge, the so-called nanoparticles are a carrier for lubricating oil additives, rather than functional additives. With the development of lubricants (technology) to this day, it is undoubtedly a case of putting the cart before the horse to solely emphasize certain special functions of nanoparticles, disregarding decades or even centuries of functional additives. I have no intention of rejecting the unique properties of so-called nano additives, and I am optimistic that they will bring revolutionary changes to lubricant additives in the future. However, at present, the application of nanotechnology in lubricants needs to solve the following problems:

① The dispersion problem of nanoparticles in oil.

We have gained some experience and have applied different solid powders in oil, such as graphite, molybdenum disulfide, polytetrafluoroethylene (PTFE), boron nitride, etc. They can indeed improve certain properties of certain oils, especially in terms of anti-wear and friction reduction, and have shown unique effects. But we also know that how to evenly disperse these solid powders in liquid oil and maintain relative stability for a long time is still a difficult problem in our industry, and it is still a challenge that lubrication technology workers need to overcome.

The following is a literature on the preparation of UDD (ultra fine diamond) using detonation method, which is added to a 15W/30 base oil sample at a concentration of 0.05-0.15%. The ITM ball disc micro traction friction meter is used to fix the sliding speed and time, measure the friction force, apply the load, calculate the wear volume loss and friction coefficient, and obtain the conclusion:

a. UDD, as an additive, has little effect on the physicochemical properties of 15w/30 lubricating oil, but can significantly improve the frictional characteristics of the oil, especially by significantly reducing the friction coefficient and increasing the load-bearing capacity.

b. The results of the bench friction and wear test show that UDD as an additive can significantly reduce the wear of the piston ring and cylinder liner.

c. Due to the nanoscale effect, 0DD can penetrate into the friction surface and form an extremely thin solid lubricating film, effectively preventing direct contact between the friction surface, thereby improving load-bearing capacity and reducing wear.

d. The friction coefficient under the lubrication of base oil containing UDD is low and stable, which may be related to the rolling friction effect of spherical DD particles on the contact surface of the friction pair. In fact, looking at various papers and literature on the application of nanoparticles in lubricants in the past decade, it has never been seen how to solve the problem of dissolution and dispersion of nanomaterials. The authors intentionally or unintentionally avoided this problem. Therefore, directly applying nanoparticles to oil and maintaining long-term uniformity and stability cannot help but raise doubts.