Nanomechanical properties inside the scratch grooves of soda–lime–silica glass

Abstract

Advanced applications of glass span the range from biomedical technology to special optical lenses to mobile phones and computers. Such advanced applications demand high-precision machining, which is like multiple single scratches occurring simultaneously on the glass surface. However, in spite of the wealth of literature on scratch deformation behavior of glass there is no significant information available on whether the nanomechanical properties are affected inside the scratch grooves. Therefore, nanoindentation experiments were deliberately conducted at a fixed load of 100 mN through the scratch grooves made at various applied normal loads (5-15 N) at a constant speed of 200 µm s −1 on polished soda-lime-silica (SLS) glass slides. The results showed that depending upon the applied normal load used to generate the scratch grooves, the nanohardness and Young's modulus inside the scratch grooves decreased by about ∼30-60% from the corresponding data of the undamaged SLS glass due to the presence of subsurface shear deformation and microcracking as observed by optical, scanning and field emission scanning electron microscopy. A model for microcracked brittle solids was utilized to explain these results.

New observations on scratch deformations of soda lime silica glass

“…These micro-cracks lead to micro-wear chip formation when the portion gets detached from all sides and further comminution of such micro-wear chips lead to formation of micro and/or nano-wear debris formation (Fig. 7(a) and (c)-(f), [26][27][28][29]). …”

“…3(a)-(f)). The critical load requirement for Hertzian tensile cracks formation calculated following [16,37] and using appropriate experimental data [26][27][28][29] was typically low at 0.0012-0.012 N. But yet the number of Hertzian tensile cracks reduced with scratching speed (Fig. 3).…”

“…A scratch tester (Model TR-102-M3, Ducom, Bangalore, India) equipped with a Rockwell C diamond indenter with~200 μm tip radius was used for this purpose. Further details may be found in [26][27][28][29]. A compound force transducer is coupled with the scratch tester which can measure both normal load (P) and the tangential force (F).…”

“…The scratching speed, the angle, the radius as well as the shape of cutter tip along with the applied normal load affect the critical condition for growth [22] of various sub-surface cracks in a wide variety of glasses when measured by different techniques [23][24][25]. We have recently reported the influence of normal load on the material removal mechanisms and the degradation of the nanomechanical properties inside the scratch groove of a soda lime silica (SLS) glass [26][27][28][29]. Very recently [29] we reported the experimental observation of the inverse power law dependencies of width, depth, wear volume of scratch grooves and the corresponding wear rate of SLS glass on the scratching speed (v) when the applied normal load was kept constant at a low value of 5 N. Extending our previous work [29] here we report the development of a new, simple model that explains the scratch behavior of SLS glass studied at three different normal loads when it is scratched with a blunt diamond indenter of~200 μm tip radius at three different scratching speeds.…”

Effect of scratching speed on deformation of soda–lime–silica glass

“…The experimental details have been already reported elsewhere [19][20][21] and hence will be only briefly mentioned here. The scratch tests were performed on mirror polished 25 × 25 × 1.40 mm soda-lime-silica glass slides (Blue Star, Kolkata, India) in air under ambient laboratory conditions at a constant applied normal load (P ) of 5 N with scratching speeds (v) of 100, 200, 500 and 1000 µm s −1 with a scratch tester (Model TR-102-M3, Ducom, Bangalore, India) equipped with a Rockwell C diamond indenter with 200-µm tip radius.…”