**2. Overview of bonded MoS2 film lubricant**

**Figure 1** shows the typical application process of the bonded MoS2 film lubricant. It can apply to various forms of products, including inner side of the holes.

**Figure 1.**

*Typical application process of bonded MoS2 film lubricant.*

The thickness of the film is typically about 10 micro-meters. Sometimes this is too large for some mechanical parts, e.g. precious ball bearings, but usually small enough to realize smooth engagement of the parts.

**Figure 2** [1] shows the cross-section of the bonded MoS2 film lubricant including substrate and film. The cross-section is enlarged vertically because it was cut diagonally. It can be seen that an intricately shaped substrate anchors the film. Such substrate surface morphology is produced by pretreatment of the substrate such as blasting. Chemical pretreatment passivates the surface of the substrate, some of which gives the surface a fine mesh-like structure. It has been reported that the final texture of the substrate surface is determined by blasting and that phosphate treatment, a type of chemical treatment, promotes significant changes in surface roughness [2]. Substrate pretreatment is an important process for providing a strong adhesion between the film and the substrate, resulting in a longer wear life of the bonded film lubricant [3].

As the lubrication performance in vacuum is excellent, the bonded MoS2 film lubricants are often used in space applications [4–6]. **Figure 3** [4] shows the joint mechanism of the robot arm of the space station: ISS. Bonded MoS2 film lubricant is applied to gears and sliding bearings in it. In general it seems to be often used for pure-sliding or rolling-sliding surfaces rather than pure-rolling surfaces.

Bonded MoS2 film lubricants are used at a variety of sliding speeds and loading conditions, but naturally their limiting PV values are smaller than oil lubrication.

**Figure 2.** *Cross-section of bonded MoS2 film lubricant [1].*

*Wear Life of Bonded MoS2 Film Lubricant DOI: http://dx.doi.org/10.5772/intechopen.99802*

#### **Figure 3.** *Joint mechanism of robot arm of space station: ISS [3].*

The working conditions under which they perform well seem to be high load and low speed conditions [7] where oil lubrication does not perform well. In this chapter, we will mainly discuss the friction and wear of bonded MoS2 film lubricants under relatively high load and low speed conditions.
