Effect of Decomposition of Chitin Polymer in Crab Shell Particles on Microstructure, Microhardness, and Water Contact Angle Behavior of Vacuum Hot-Pressed Mg-AZ91 Composite

Abstract In this study, as an alternative to typical ceramics, crab shell particles (CSP) are reinforced in Mg-AZ91 alloy in varying wt% (6, 12, and 18) via a vacuum hot press machine at the sintering temperature of 455 °C. The X-ray diffractometer (XRD) result proves that the important phase composition of CSP is chitin and Mg-calcite. Due to its low thermal stability, the chitin polymer decomposed at a sintering temperature of 455 °C and became bio-carbonaceous char. It has a hydrophilic nature. The decomposition of chitin increases the pores and reduces the density and contact angle from 76.1 deg to 59.8 deg in the specimen. There is a uniform distribution of magnesium calcite in the composite, but the distance between the particles is greater, as confirmed through scanning electron microscope (SEM) images. The presence of bio-carbonaceous char and the greater distance between magnesium calcite have reduced the hardness values from 92 to 66 HV0.3.