Abstract
Understanding the phase transformations/developments that result due to varying the production parameter of
engineering materials is vital to development of new materials. The effects of yttria and niobium oxide on the phase changes
and mechanical properties of mullite fiber reinforced zircon-zirconia ceramic composites produced by in-situ sintering of raw
materials was investigated. Varied amounts of powder zirconia, yttria and niobium oxide were mixed in a turbula mixer with
a fixed composition of clay (70% volume) of known mineralogical composition and mechanically milled in a planetary ball
mill. The blended powders/clay were compacted into standard sample dimensions, and finally fired at 1400°C and held at
varied time of one, two and three hours. The fired samples were characterized using ultra-high resolution field emission
scanning electron microscope (UHR-FEGSEM) equipped with energy dispersive spectroscopy (EDX), and X-ray
diffractometry (XRD). Various mechanical properties of the sintered samples were also investigated. It was observed that the
investigated mechanical properties (with the exception of shrinkages) improved with the amount of raw zirconia initially used
in the samples. It was also observed that addition of niobium oxide favours the formation polymignite phase, while the
presence of both yttria and niobium oxide in the raw materials resulted in the formation of fergusonite phase in the samples.
Both additives favour the phase transformation of zirconia from monoclinic to tetragonal and cubic phases even at
temperature as low as 1400°C. It was concluded that the improved mechanical properties of the samples was due to
strengthening by both mullite fibers reinforcement and phase transformation strengthening.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1001844 |
| Date | 01 December 2015 |
| Creators | Aramide, FO, Alaneme, KK, Olubambi, PA, Borode, JO |
| Publisher | International Journal of Materials and Chemistry |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | |
| Rights | © 2015 Scientific & Academic Publishing |
| Relation | ResearchGate |
Page generated in 0.0021 seconds