On the behaviour of obsidian under scratch test

Micro-scale deformation of gypsum during micro-indentation loading

“…5 for loads of 0.25 N, 0.49 N, 1.96 N, and 4.91 N. Cracking is commonly noted, but crack lengths and indentation features are often not typically characterized following micro-indentation experiments [54]. The visible crack density (i.e., the percentage of the surface that contains visible cracks) on the surface of the indentation zone decreases substantially as the load is increased.…”

Effect of load in scratch experiments on soda lime silica glass

“…However, to grind and polish glass with requisite dimensional precision is a big challenge as the characteristic brittleness makes it prone to undergo brittle fracture. That is the reason why the scientific issues behind the material removal mechanisms during the grinding and polishing of brittle materials like glasses as well as ceramics and glass ceramic have been receiving a huge research interest [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Recent works on alumina [21], C/C composite [22], plasma sprayed ceramic coating [23], titanium oxide thin film on glass [24], ZrB 2 -SiC composite [25,26], sialon ceramics [27], dental ceramics [28], DLC coatings [29], calcium phosphate coatings [30], and chromium nitride and titanium nitride coatings [31] provide the invaluable importance of scratch testing for understanding the material removal mechanisms as well as coating failure mechanisms.…”

“…Depending upon the normal load in the incremental scratch test on obsidian, three zones e.g. a micro-ductile zone, a micro-cracking zone and a micro-abrasive zone were reported [18]. Scratch behavior of SLS glasses was very sensitive to the loading history, the hygrometry level, the chemical structure and/or composition of the lubricant and the glass composition [19,20].…”

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

“…The transition from the deformation to fracturecontrolled process [11] of damage evolution and consequent material removal mechanisms happen at P c in glass through the spatial interaction among neighboring scratches [12]. The recent study on obsidian [13] confirms the presence of a micro-ductile, a microcracking and a micro-abrasive zone whereas scratch damage evolution was very sensitive to the loading history, the hygrometry level and the glass composition [14]. The speed of scratching, the angle, the radius and the shape of cutter tip, the applied normal load affect the critical condition for growths [15] of various subsurface cracks in different glasses as measured by a laser displacement sensor [16], chemical etching [17] and ball-dimple technique [18].…”