Abstract
We studied the fabrication of functionally graded Al2O3–CeO2-stabilized-ZrO2 (CTZ) ceramics by spark plasma sintering. The ceramic composite exhibits a gradual change in terms of composition and porosity in the axial direction. The composition gradient was created by layering starting powders with different Al2O3 to CTZ ratios, whereas the porosity gradient was established with a large temperature difference, which was induced by an asymmetric graphite tool configuration during sintering. SEM investigations confirmed the development of a porosity gradient from the top toward the bottom side of the Al2O3–CTZ ceramic and the relative pore volume distributed in a wide range from 0.02 to 100 µm for the samples sintered in asymmetric configuration (ASY), while for the reference samples (STD), the size of pores was limited in the nanometer scale. The microhardness test exhibited a gradual change along the axis of the ASY samples, reaching 10 GPa difference between the two opposite sides of the Al2O3–CTZ ceramics without any sign of delamination or cracks between the layers. The flexural strength of the samples for both series showed an increasing tendency with higher sintering temperatures. However, the ASY samples achieved higher strength due to their lower total porosity and the newly formed elongated CeAl11O18 particles.
Highlights
Gradient properties were created in the ceramic sample in two ways: (1) making up the bulk from layers of different composition, which leads to a chemical gradient, as well as (2) establishing a temperature gradient in the ceramic body during sintering, which results in a porosity gradient
The temperature gradient was generated by the asymmetric graphite configuration of the sample during the spark plasma sintering (SPS) sintering process, to our previous study [42]
As (2) establishing a temperature gradient in the ceramic body during sintering, which results in a porosity gradient
Summary
FGMs [4] are characterized by a gradual transition of the composition and/or physical properties of the material along the bulk in one or more directions. It results in bulky materials having different behaviors in the various parts of the material tailored to the application. FGMs can be classified mainly into continuous and step-graded types depending on the interface conditions, but definite interfaces cannot be observed in either case. In this regard, the local concentration of stress, which may induce delamination within the material, can be avoided [5]
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.
