γ‐Y ₂ Si ₂ O ₇ , a Machinable Silicate Ceramic: Mechanical Properties and Machinability

Abstract

In this paper, the mechanical properties of bulk single‐phase γ‐Y 2 Si 2 O 7 ceramic are reported. γ‐Y 2 Si 2 O 7 exhibits low shear modulus, excellent damage tolerance, and thus has a good machinability ready for metal working tools. To understand the underlying mechanism of machinability, drilling test, Hertzian contact test, and density functional theory (DFT) calculation are employed. Hertzian contact test demonstrates that γ‐Y 2 Si 2 O 7 is a “quasi‐plastic” ceramic and the intrinsically weak interfaces contribute to its machinability. Crystal structure characteristics and DFT calculations of γ‐Y 2 Si 2 O 7 suggest that some weakly bonded planes, which involve Y–O bonds that can be easily broken, are the sources of the low shear deformation resistance and good machinability.