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

Abstract

The grinding and polishing of a fundamentally brittle material like glass to an utmost precision level for ultra-sophisticated applications ranging from mobile devices to aerospace as well as space shuttle components to biomedical appliances pose a big challenge today. Looking simplistically, the grinding and polishing processes are basically material removal by multiple scratching at a given speed. Unfortunately however, the role of the scratching speed in affecting the material removal mechanism in sodalime-silica (SLS) glass is yet to be comprehensively understood. Therefore, the present work explores the surface and subsurface deformation mechanisms of SLS glass scratched under a normal load of 5 N at various speeds in the range of 100-1000 µm s −1 with a diamond indenter of ∼200 µm tip radius. The results show important roles of the time of contact, the tensile stress behind the indenter and the shear stress just beneath the indenter in governing the material removal mechanisms of the SLS glass.

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). The corresponding SEM [26,27,29] photomicrographs for an applied load of 5 N showed the genesis and the mode of propagation of the edge cracks in tracks made at 100 ( Fig. 4(a)) and the damage in the scratch track much less for 1000 μm/s ( Fig.…”

“…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).…”

“…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.…”