Microstructure in Pressureless-Sintered Iron-Containing Hydroxyapatite/Titanium Composites

Abstract

Pure hydroxyapatite (HA) is brittle and it cannot be directly used for the load-bearing biomedical applications. Aim of this paper was to present a new iron-containing hydroxyapatite/titanium composites synthesized via pressureless sintering at a relatively low temperature of 1000°C using nano-sized HA powders and Ti-33%Fe mixed powders. The microstructure and composition of the new type composites were evaluated. The results showed that the uniformly distributed reinforcing particles had a unique and favorable core/shell microstructure after sintering that consisted of outer titanium and inner iron. The mechanism for the formation of the core/shell structure was discussed. The addition of iron reduced the decomposition rate of HA and the interaction between HA and titanium.

Research Progress Regarding Interfacial Characteristics and the Strengthening Mechanisms of Titanium Alloy/Hydroxyapatite Composites

“…% Fe) composite consisted of HA and some new phases, such as Ti, Fe, TiFe, β-CaTiO 3, etc. [ 12 , 38 ]. The contents of β-TCP and Ca 4 O(PO 4 ) 2 (TTCP) were significantly decreased, as these second phases were not detected by XRD [ 12 , 38 ].…”

“…[ 12 , 38 ]. The contents of β-TCP and Ca 4 O(PO 4 ) 2 (TTCP) were significantly decreased, as these second phases were not detected by XRD [ 12 , 38 ]. This showed that the addition of Iron can inhibit decomposition of HA and chemical reactions with Ti, which are related to faster diffusion rate of Iron element in Titanium at 836 °C [ 12 , 38 ].…”

“…The outer shell was Titanium and the inner was Iron. This interface topography was formed in three steps [ 38 ]: (1) Ti and Fe elements were randomly distributed when Ti-33 wt. % Fe composite particles were added.…”

“…Residual Iron was retained between Ti-33 wt. % Fe particles and formed an Iron-based core [ 38 ]. Marcu et al found that there are some black zonal materials and columnar grains in Ti-6Al-7Nb-HA composite prepared by selective laser melting [ 22 ], because the microstructure of composites was affected by local heating in the preparation process.…”

“…Chetibi et al found that the composite coating produced dense uniform nanoparticle morphologies after adding multi-walled carbon nanotubes (MWCNTs), which improved the adhesion strength between coating and substrate [ 36 ]. Moreover, other strengthening phases such as Zn element and some metal oxides can also improve the properties of materials due to their interactions with HA or Titanium alloys [ 37 , 38 , 39 , 40 ]. For example, Lugovskoy et al found that the reaction between ion phosphate and Hydrated Titanium/Hydroxide from titania film can promote the formation of HA, which improved the interface bonding strength between HA and Titanium alloy substrate [ 16 ].…”