Thermal and microstructural analysis of doped alumina nanofibers

• A very high aspect ratio (∼106) γ-alumina nanofibers of 7 nm diameter were studied.
• Dopants ZrO2 and α-Al2O3 were applied by chemical liquid deposition technique.
• Thermal behavior of dopants was analyzed with TG-DSC-FTIR.
• Sintered specimens have shown an increase in microhardness by 30–55%

Gamma-alumina nanofibers of 7 nm in diameter and aspect ratio ∼106 were doped with 10% of zirconia or alpha-alumina by in situ chemical liquid deposition (CLD) technique. Thermal behavior and decomposition kinetics of dopant nano-layers were conducted using simultaneous coupled thermal analysis (TG-DSC-FTIR) to optimize the processing conditions and suggest possible reaction mechanisms. SEM and TEM analysis of fine structure of functionalized nanofibers revealed changes in dopants localization at the base nanofibers. The effect of dopants on thermally-treated materials properties treatment was evaluated after consolidation of the samples by HIP at 1200 °C and 150 MPa. These sintered specimens have shown an increase in microhardness (HV) by 30% and 55% for alumina- and zirconia-doped materials, respectively. The mechanism and kinetics of the dopants precursor reactions are discussed on the basis of the simultaneous thermal analysis.