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Ductile to Brittle Transition of AlON & Sapphire


Project Time Frame: December 2008 – March 2009 

Material: (1) Single Crystal Sapphire (Al2O3)

           (2) AlON Optical Ceramic (Al23O27N5)         

Project Aim: To establish a Ductile to Brittle Transition (DBT)/critical depth of cut for the material with a specifically defined cutting direction and crystal orientation.

Project Description: ALON and Sapphire, like other brittle materials, is known for its poor machinability. However, ductile-regime machining is possible under certain conditions. This can be achieved if machining occurs at depths less than the critical depth of cut. Beyond this value, a Ductile-to-Brittle Transition (DBT) occurs and the material behaves in a brittle-fracture manner. The purpose of this research is to determine the DBT for ALON and Sapphire by performing scratches with varying loads. The depth of cut is adjusted by altering the applied load (thrust force) over an estimated range in order to cover the entire ductile to brittle-regime and the corresponding material removal behavior. The scratch tests were carried out on the Universal Micro Tribometer (UMT). The scratches were imaged and measured using the WYKO white light interferometer.    

Project in Detail: View

Material Data Sheet: View