| GUO Jiale,YI Hao,ZHU Limin,SUN Yuli,ZUO Dunwen.Material Removal Mechanism and Sub-surface Cracking in Quartz Glass Based on Nano-scratch[J],53(16):151-158 |
| Material Removal Mechanism and Sub-surface Cracking in Quartz Glass Based on Nano-scratch |
| Received:October 07, 2023 Revised:December 20, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.16.012 |
| KeyWord:quartz glass material removal scratch profile subsurface cracks dynamic loading fracture mechanisms |
| Author | Institution |
| GUO Jiale |
College of Mechanical & Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing , China |
| YI Hao |
Shanghai Aerospace Control Technology Institute, Shanghai , China |
| ZHU Limin |
Shanghai Aerospace Control Technology Institute, Shanghai , China |
| SUN Yuli |
College of Mechanical & Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing , China |
| ZUO Dunwen |
College of Mechanical & Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing , China |
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| Abstract: |
| Nano-scratch experiment is a commonly employed method for studying the behavior of materials, specifically focusing on material properties and mechanical responses at the nanoscale. The work aims to conduct nano-scratch experiments on fused silica glass, so as to gain deeper insights into the removal behavior of individual abrasive particles and investigate the mechanisms of material removal and the propagation of subsurface cracks under dynamic loading conditions. Circular samples of fused silica glass with dimensions of ϕ30 mm×6 mm were prepared for the scratch experiments. Prior to experiments, the samples underwent a polishing pretreatment to reduce surface roughness to approximately 3 nm. The experiments were carried out with a Nano Indenter G200 nano-scratch instrument, at a constant scratch speed of 30 μm/s and a scratch length of 1 mm. The loads ranging from 0 to 300 mN were gradually applied to the samples, and the profiles of the scratches were recorded. To investigate the subsurface crack morphology, samples were sectioned near the scratch location. Cross-sectional views of the scratches were obtained through successive polishing steps, followed by etching with a 2% HF solution. Scanning electron microscopy (SEM) was employed to observe the surface topography of the scratches and the morphology of subsurface cracks at various stages along the scratch. Comprehensive analysis of the scratch profile curves and cross-sectional views at different stages revealed the following:when the dynamic load was less than 118 mN, the scratch exhibited a uniform and smooth appearance with plastic deformation of the material. Subsurface cracks were not observed at this stage. For dynamic loads greater than 118 mN but less than 245 mN, the scratch showed noticeable material pile-up on the right side and slight brittle damage on the left side. The scratch profile exhibited significant fluctuations, indicating a transition from plastic to brittle behavior. Subsurface cracks began to form and propagate, primarily in the form of "eight"-shaped radial cracks and transverse cracks. When the dynamic load exceeded 245 mN, the scratch exhibited extensive fragmentation and spalling. The scratch profile displayed severe fluctuations, and the material reached a state of complete brittle fracture. Subsurface cracks continued to expand, forming multiple intersecting radial cracks, leading to material failure. This resulted in the gradual formation of central cracks and a "claw" morphology with multiple coexisting radial cracks. The material removal process of fused silica glass underwent three distinct phases with increasing dynamic loads:elastic-plastic deformation, plastic-brittle transition, and complete brittle fracture. Subsurface cracks, affected by dynamic impact loads, initiated from the point of loading and continually propagated along the direction of maximum stress, ultimately extending to the material surface and leading to extensive brittle fracture. The mechanical properties of fused silica glass were affected by the impact loads, with dynamic fracture toughness and dynamic hardness being directly proportional to the flow stress during loading. By combining the JC constitutive equation for fused silica glass, a new formula for the critical cutting depth of plastic-brittle transition was established. It was found that the critical cutting depth was directly proportional to the elastic modulus and inversely proportional to the flow stress of the material. Under dynamic loading conditions, the dynamic elastic modulus of the material experienced a slight decrease, while the flow stress significantly increased. Consequently, fused silica glass develops subsurface cracks more rapidly under dynamic loads, resulting in a reduced critical cutting depth. This effect accelerates the transition of the material into the plastic-brittle transition stage. |
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