The paper analyzes the influence of porosity of hydroxyapatite (HA)/multi-wall carbon nanotubes (MWCNTs) composites on their fracture toughness. It is found that two competing factors affect the resulting fracture toughness. On the one hand, MWCNTs, which are stronger than the surrounding HA matrix, promote the increase in the fracture toughness owing to the possible crack path deflection from the planar geometry, that leads to a decrease in the crack driving force. On the other hand, the higher MWCNT concentration leads to the reduction in the composite porosity. The computer simulation of the crack formation in HA composite with different porosity shows that the lower porosity provided by the sintering activation due to the MWCNT addition, leads to a reduction in the fracture toughness of ceramics. It is shown that the MWCNT addition in the amount of less than 0.5 wt.% does not lead to a significant growth in the fracture toughness due to these two competing factors.

本文分析了羟基磷灰石（HA）/多壁碳纳米管（MWCNTs）复合材料的孔隙率对其断裂韧性的影响。发现两个竞争因素影响所得的断裂韧性。一方面，由于周围的裂纹路径可能偏离平面几何形状，因此比周围的HA基体更强的MWCNT促进了断裂韧性的提高，从而导致裂纹驱动力降低。另一方面，较高的MWCNT浓度导致复合材料孔隙率的降低。对具有不同孔隙率的HA复合材料中裂纹形成的计算机模拟表明，由于添加了MWCNT，烧结活化提供的孔隙率较低，导致陶瓷的断裂韧性降低。