Effect of humidity on friction, wear, and plastic deformation during nanoscratch of soda lime silica glass

Abstract

Physical flaws and defects on glass surfaces are known to reduce the mechanical strength and chemical durability of glass. The formation of surface defects depends not only on the mechanical conditions of the physical contact but also on the environment in which the contact is made. In this study, the nanoscratch behavior of soda lime silica (SLS) glass was investigated in 10% and 60% relative humidity (RH) conditions. Based on the evolution of friction and scratch depth, the deformation of SLS glass surface could be divided into four regimes: elastic deformation and recovery (E), RH-independent mild plastic deformation (P-1), RH-dependent intermediate plastic deformation (P-2), and RH-independent severe plastic formation (P-3). It is quite surprising to observe that plastic deformation of the glass surface has dependence on RH of the environment (outside the glass) because plastic deformation is the process occurring below the surface (inside the glass) by the externally applied load. From this result, it can be inferred that frictional energy dissipation mode at the sliding interface, which is a function of adsorbed water molecules, influences the subsurface deformation mode. Although friction, wear, and subsurface deformation/damage are all coupled, there is no direct one-on-one correlation among them.

Mixed modifier effects on structural, mechanical, chemical, and mechanochemical properties of sodium calcium aluminosilicate glass

“…Moreover, previous work has demonstrated that failure mechanisms during indentation testing under normal stress made with a sharp indenter are markedly different from the damage mode under interfacial shear (friction) generated by a smooth counter‐surface 62 . For example, the compressive stress that increases hardness in chemically strengthened glasses has been shown to deteriorate the high RH wear resistance when evaluated under frictional shear 14,63 . This is because wear tests involve mechanochemical reactions, including hydrolysis reactions that are enhanced by the distortion of the silicate network 16,25 …”

“…62 For example, the compressive stress that increases hardness in chemically strengthened glasses has been shown to deteriorate the high RH wear resistance when evaluated under frictional shear. 14,63 This is because wear tests involve mechanochemical reactions, including hydrolysis reactions that are enhanced by the distortion of the silicate network. 16,25 The high wear rate for the NAS glass (R = 0) can be intuitively explained by the hygroscopic nature of the glass, discussed previously, and shown graphically in Figure S2.…”

Indentation and abrasion in glass products: Lessons learned and yet to be learned

“…It should also be noted that environmental effects, such as humidity, can alter the interfacial friction between the indenter surface and the glass surface moving due to shear flow, which eventually alter the degree of plastic deformation. 126…”

“…A more fundamental approach would be to couple tribological tests with structural investigation tools revealing how the residual stresses interact with a statistical distribution of flaws. It should also be noted that environmental effects, such as humidity, can alter the interfacial friction between the indenter surface and the glass surface moving due to shear flow, which eventually alter the degree of plastic deformation 126 …”

Development of a wear coefficient equation for the A A7075-B4C composite – steel interface

“…Plastic deformation wear, as characterized by flow and yielding, contributes to material displacement and surface modification. Grooving, surface flattening, flow patterns and micro cracking are the microstructural features of Plastic deformation wear [4]. Delamination wear occurred by the peeling of the surface categorized by surface flaking, material fracture, crack networks and void formation [5].…”