Nano-to-microscale ductile-to-brittle transitions for edge cracking suppression in single-diamond grinding of lithium metasilicate/disilicate glass-ceramics |
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| Affiliation: | 1. School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China;2. School of Mechanical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia;1. School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062, China;2. School of Material Science and Engineering, Chang’an University, Xi’an 710064, China;1. School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China;2. School of Material Science and Energy Engineering, Foshan University, Foshan, Guangdong 528000, China;1. AVIC Chengdu Aircraft Industrial (Group) Co., Ltd., Chengdu, China;2. State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China;1. School of Optical and Electronic Information, Key Lab of Functional Materials for Electronic Information (B) of MOE, Huazhong University of Science and Technology, Wuhan, PR China;2. Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, PR China;3. Wenzhou Advanced Manufacturing Institute, Huazhong University of Science and Technology, Wenzhou, PR China;4. School of Materials Science and Engineering, Jingdezhen Ceramic University, Jingdezhen 333403, PR China;5. College of Electronic Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, PR China |
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| Abstract: | To suppress grinding-induced edge cracks in dental lithium metasilicate/disilicate glass-ceramics (LMGC/LDGC), this paper established a contact stress model for single-diamond grinding (SDG) to relate their crack generation and ductile-to-brittle transition (DBT) thresholds with the mechanical properties, diamond tool profiles and process variables. Nanoindentation, friction test and SDG were conducted to unravel material responses and dynamic diamond grit-workpiece interactions to determine the DBT thresholds. The nanoindentation revealed significant indentation size effects (ISEs) on the hardness and elastic moduli of the ceramics. SDG clearly elucidated their DBT behaviors, wherein edge cracks initiated at diamond peripheries when the concurrent contact stresses reached the DBT thresholds. Accordingly, the indicated critical cutting depths for DBT may be changed from the nanoscale to the microscale by increasing the tool radius and reducing the machining speed. This research contributes to edge crack suppression for ductile machining of brittle materials at large removal rates. |
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| Keywords: | Lithium metasilicate/disilicate glass-ceramics Edge cracks Contact stress Ductile-to-brittle transition Single-diamond grinding |
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