TIB Repositorium · 1990 · 17 citations · 0 references
Natural SciencesMaterials EngineeringMaterials ScienceCeramic MaterialsCeramicsMaterials ChemistryCrack AssessmentFracture MechanicsFracture ToughnessGlass MaterialsSilicate MineralogySilicate MineralsCrack Analysis In GlassCrack GrowthCrack Growth AnalysisCrack Growth KineticsCrack Growth RateFracture Of GlassesGlass Fracture BehaviorSilicate Glasses
The crack growth on silicate glasses of the systems <i>x</i> Na<sub>2</sub>O - (100-<i>x</i>) SiO<sub>2</sub>, <i>x</i> Na<sub>2</sub>O - 11 Al2O<sub>3</sub> - (89-<i>x</i>) SiO<sub>2</sub>, <i>x</i> Na<sub>2</sub>O - 11 B<sub>2</sub>O<sub>3</sub> - (89-<i>x</i>) SiO<sub>2</sub>, <i>x</i> Na<sub>2</sub>O - 7 CaO - (93-<i>x</i>) SiO<sub>2</sub> and <i>x</i> Na<sub>2</sub>O - 17 CaO - (83-<i>x</i>) SiO<sub>2</sub> as well as on two commercial glasses (soda-lime-silica and sodium borosilicate glass) in water, acids and bases has been studied. In alkali oxide containing silicate glasses the crack-growth mechanism is based on a stress-stimulated splitting of siloxane bridges due to attack of both hydroxide ions (dominant in NaOH) and molecular water (dominant in LiOH). Real network dissolution with a rate like the crack-growth velocity (occurring in hydrofluoric acid or in water on extremely leachable glasses) leads to a plateau-like region of the crack growth. The threshold of crack growth in alkali-containing glasses is caused by alkali leaching forming a surface-near glass layer with modified mechanical properties within the cracks. Therefore, this threshold is enhanced with increasing pH value of the medium. The two commercial multicomponent glasses behave in a similar way like the investigated model glasses. The crack-growth curves indicate that the failure risk decreases in the order base, water, acid as well as with increasing concentrations of base or acid.