Влияние пористости на величину коэффициента трещиностойкости Kc биокомпозита гидроксиапатит - многостенные углеродные нанотрубки

Abstract

The influence of the porosity on the values of the fracture toughness coefficient Kc of hydroxyapatite - multi-walled carbon nanotube biocomposite materials (HA-MWCNTs) has been analyzed. It has been found that on the resulting values of the coefficient Kc two competing factors are affected. On the one hand, the additives of multiwalled carbon nanotubes (MWCNTs) mechanically stronger than the surrounding hydroxyapatite (HA) matrix leads to increase the Kc due to the possible change the direction of the crack propagation from planar geometry and leads to a decrease of the force of the crack propagation. On the other hand, the increase of the content of MWCNT additives leads to a decrease of the porosity of the composite. Numerical computer simulation of crack formation in HA with various porosities was performed. It was shown that a decrease of porosity, that appear due to the activation of the sintering process as a result of intercalation of MWCNT additives to the HA, leads to a decrease of the crack resistance coefficient Kc of the ceramic. It has been shown that MWCNT additives in the content of less than 0.5 mass. % do not lead to a significant increase of the fracture toughness coefficient Kc due to competition between these two mechanisms.