Publication:
Alkaline-Activation technique to produce low-temperature sintering activated-HAp ceramic
Alkaline-Activation technique to produce low-temperature sintering activated-HAp ceramic
Date
2023
Authors
Wan Mohd Arif W Ibrahim
Mohd. Mustafa Al Bakri Abdullah
Noorina Hidayu Jamil
Hasmaliza Mohamad
Mohd Arif Anuar Mohd Salleh
Andrei Victor Sandu
Petrica Vizureanu
Madalina Simona Baltatu
Patimapon Sukmak
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Research Projects
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Abstract
The fabrication of hydroxyapatite (HAp) ceramics prepared by existing conventional sintering requires high-temperature sintering of 1250 °C to 1300 °C. In this paper, the activated metakaolin (MK)/HAp specimens were prepared from varied mix design inputs, which were varied solid mixtures (different amounts of MK loading in HAp) and liquid-to-solid (L/S) ratios, before being pressed and sintered at 900 °C. Phase analysis, thermal analysis, surface morphology, and tensile strength of the specimens were investigated to study the influences of the Al, Si, Fe, Na, and K composition on the formation of the hydroxyapatite phase and its tensile strength. XRD analysis results show the formation of different phases was obtained from the different mix design inputs HAp (hexagonal and monoclinic), calcium phosphate, sodium calcium phosphate silicate and calcium hydrogen phosphate hydrate. Interestingly, the specimen with the addition of 30 g MK prepared at a 1.25 L/S ratio showed the formation of a monoclinic hydroxyapatite phase, resulting in the highest diametrical tensile strength of 12.52 MPa. Moreover, the increment in the MK amount in the specimens promotes better densification when sintered at 900 °C, which was highlighted in the microstructure study. This may be attributed to the Fe2O3, Na2O, and K2O contents in the MK and alkaline activator, which acted as a self-fluxing agent and contributed to the lower sintering temperature. Therefore, the research revealed that the addition of MK in the activated-HAp system could achieve a stable hydroxyapatite phase and better tensile strength at a low sintering temperature.
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Keywords
Alkali-activated-hydroxyapatite,
Hydroxyapatite phase,
Diametrical tensile strength,
Monoclinic