**3.2 Adhesive wear**

When one surface slides over the other interaction between the high spots produces occasional particles of wear debris. Mild adhesion is the expulsion of films, for example, oxides at a lower rate. Severe adhesion is the evacuation of metal because of tearing, breaking, and liquefying of metallic intersections (**Figure 3**). This prompts scraping or annoying of the surfaces and even seizure.

Adhesive wear can be found between surfaces during frictional contact and by and large alludes to undesirable dislodging and connection of wear debris and material mixes starting with one surface then onto the next. Two glue wear types can be recognized.


Yunxia et al. [3] investigated about the adhesive wear phenomena of aero-hydraulic spool valves and the investigation revealed the trimming and transformation of outer material due to the shear fracture of the bonded areas (**Figure 4**). It has been also claimed that the above mentioned work is an evidence of the adhesion wear process between spool and valve sleeve.
