Abstract
Nacre-like alumina manufactured using spark plasma sintering shows a strikingly different mechanical behaviour compared to conventional alumina. A range of sintering conditions were applied to micron-sized alumina platelet powders to form alumina with different nacre-like microstructures, density, grain size and flexural strength. We show that a microstructure of aligned sintered platelets not only mitigates the typical issue of brittleness, but also has extraordinary energy absorption capabilities. It can withstand an impact with up to three times the kinetic energy required to break monolithic alumina while maintaining structural integrity. The high-rate compressive strength is shown to be more than 50% higher than that of monolithic alumina and we show energy absorption mechanisms such as crack deflection and branching to be present. Our approach provides a fast and effective way of manufacturing aligned nacre-like ceramic microstructures that maintain structural integrity through energy dissipation and interlocking mechanisms.
Highlights
IntroductionWe present a nacre-inspired material made from alumina platelets. Nacre, known as mother of pearl, is the skeletal structure found in Gastropoda, Bivalvia and Cephalopoda mollusc shells, and is much stronger than any other mollusc shell structure independent of the type of loading [1]
In this work, we present a nacre-inspired material made from alumina platelets
Alumina platelets were sintered at 1200 °C, 1300 °C and 1400 °C at a pressure of either 50 MPa or 70 MPa
Summary
We present a nacre-inspired material made from alumina platelets. Nacre, known as mother of pearl, is the skeletal structure found in Gastropoda, Bivalvia and Cephalopoda mollusc shells, and is much stronger than any other mollusc shell structure independent of the type of loading [1]. Confirm Lin and Meyers’ views and conclude through a theoretical calculation that the mineral bridges effectively hinder crack extension Another factor that comes into play in the sliding behaviour of nacre platelets, is platelet overlap. To investigate nacre-like microstructures using SPS, alumina platelets were sintered at different combinations of sintering temperature and pressure, generating a range of materials with distinct microstructural features, mainly in terms of size of the platelet-like grains. Since alumina platelet powders have a grain size that is much larger, and since we must consider the poorer packing of plateletpowders, we have taken these temperatures as a lower bound, And have densified at 1200 °C, 1300 °C and 1400 °C to see the effect on the microstructure and related mechanical properties. Direct comparison of the results of these tests for nacre-like and monolithic alumina specimens show strikingly different failure mechanisms, highlighting an enormous energy-absorbing capability of the manufactured nacre-like specimens
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