Molybdenum DiSulfide Coating
graph chart of Surface Engineering Technologies' molybdenum disulphide process results

Surface Engineering Technologies’ molybdenum disulphide process results

Molybdenum DiSulphide (MoS2) is a material with a unique crystal structure which allows it to have one of the lowest coefficients of friction of any solid. Compared to all other lubricating coatings, it consistently has the lowest cof. of friction (~.01-.03) for even the largest loads and highest operating temperatures (800° F). MoS2 has strong bonds in the x-y plane and extremely weak bonds in the z-direction, allowing for plates of MoS2 to slide over each other like playing cards with minimal resistance. Naturally occurring MoS2 has most of these plates in a randomized orientation which causes the plates to lock up while sliding, however, using advanced surface engineering techniques the structure of MoS2 can be deposited completely uniform on the surface of parts with a consistent orientation of the MoS2 plates.

Magnetron Sputtered is the preferred method of coating a completely uniform crystal structure in the optimal origination. Processes that apply MoS2 by burnishing, rubbing on, power baking, or spray methods have a tendency to produce completely randomized crystal structures as well drastically reducing the cycle life and performance of the coating. These treatments also cause decreased lifetimes due to their lack of a strong bonding layer with the surface of the part.

photo of surface engineering technologies plant equipment for Molybdenum Disulfide Machine

Molybdenum DiSulfide Magnetron Sputtered Vapor Deposition machine at Surface Engineering Technologies.

When applying MoS2 by magnetron sputtering in a vacuum chamber, the part surface and the coating as it forms can be bombarded with Argon plasma to create a bonding interlayer which greatly increases the maximum adhesion of the coating.

Another major issue in the consideration of using MoS2 as a solid lubricant is the deterioration of MoS2 coating when exposed to humid conditions. When exposed to water, MoS2 can absorb the water which will result in the breakdown of the MoS2 into other compounds. A further advantage of the Magnetron Sputtered process is that other proprietary elements can be added to the MoS2 coating to prevent the absorption of water. By adding the other material to the MoS2, MoS2 coated end mills can successfully be used in cutting fluids containing 93% water.

photo of sparks coming off plasma tool

At Surface Engineering Technologies LLC, we have developed a unique coating consisting of MoS2 and other elements that when applied in a vacuum chamber using Magnetron Sputtered Vapor Deposition will produce a long lasting solid lubricant coating with a coefficient of friction as low as .01 and at the same time allow operation in humid environments. Our process has been used on all sorts of critical applications, from satellites and the space station, to engine parts used in racing conditions. Our MoS2 has also been used in combination with other surface treatments such as Titanium Nitride to increase hardness or Heavy Metal Ion Implantation to create some exceptional after market and specialty OEM parts.

Keegan Knorr
Director of Surface Engineering