Abstract
The present work merges two key strategies for the manufacturing of advanced ceramics, in particular, the development of functionally graded materials (FGMs) and the addition of graphene-based fillers into a ceramic matrix. A silicon nitride/reduced graphene oxide FGM composite is produced, in one step, from a single powder composition using the spark plasma sintering (SPS) technique with an asymmetric setting of the punches and die to create a continuous temperature gradient along the cross section of the powder compact. A deep microstructural and mechanical characterization has been done across the specimen thickness. The FGM composite exhibits bottom-top gradients in both the matrix grain size (150% increase) and α-phase content (89→1%). The FGM bottom surface is 10% harder than the top one and, on the other hand, the latter is 15% tougher. The presence of reduced graphene oxide sheets homogeneously distributed within the ceramic composite reduces the mechanical gradients compared to the monolithic silicon nitride FGM, although allows reaching a maximum long-crack toughness value of 9.4 MPa·m1/2. In addition, these graphene-based fillers turn the insulating ceramics into an electrical conductor material.
Highlights
The development of advanced engineering materials with graded compositions and/or microstructures and properties, commonly known as functionally graded materials (FGMs) [1], has experienced a continuous growth since 1990s
Ceramic FGMs display a promising range of industrial applications, including aerospace, automotive, energy production and biomedicine [2]
One possible solution is to develop a linear thermal gradient along the powder compact by using the spark plasma sintering (SPS) technique, which leads to a continuous change of the composition and/or microstructure throughout the material [3,4,5]
Summary
The development of advanced engineering materials with graded compositions and/or microstructures and properties, commonly known as functionally graded materials (FGMs) [1], has experienced a continuous growth since 1990s. Graded ceramics have shown a comparable tendency accounting for around 25% of the total number of published documents (according to the Scopus database). One possible solution is to develop a linear thermal gradient along the powder compact by using the spark plasma sintering (SPS) technique, which leads to a continuous change of the composition and/or microstructure throughout the material [3,4,5]. In this way, Hong et al [3] manufactured
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
