Carbon nanotube reinforced hydroxyapatite composite coatings produced through laser surface alloying

Abstract

Carbon nanotube (CNT) reinforced hydroxyapatite composite coatings have been successfully fabricated by laser surface alloying. The phase compositions and the microstructure of the composite coatings were studied using X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). TEM observation showed that a large amount of CNTs can be found with their original tubular morphology in the composite coatings, even though some CNTs react with titanium element in the substrate during laser irradiation. Additionally, measurement on the elastic modulus, hardness of the composite coatings by nanoindentation tests indicated that the mechanical properties are affected by the amount of CNTs in the starting precursor materials. Therefore, CNT reinforced hydroxyapatite composite coating is a promising coating material for high-load-bearing metal implants.

Calcium orthophosphate-based biocomposites and hybrid biomaterials

“…They found that the higher the loading of nanotubes, the better the properties. Namely, at 20 wt% loading, hardness was increased by 43% and Young's modulus by 21% over a single-phase HA coating [883]. Scratching test results indicated that as alloyed HA biocomposite coatings exhibited improved wear resistance and lower friction coefficient with increasing the amount of carbon nanotubes in the precursor material powders [882].…”

“…Physico-chemical characterization of these biocomposites showed that nucleation of CDHA initiates through the carboxyl group [247]. Hot-pressing [879], plasma spraying [880], and laser surface alloying [881][882][883] techniques might be applied as well. The research on calcium orthophosphate (up to now, only apatites)/carbon nanotube biocomposites is in its early stages, with the first papers published in 2004 [246,433].…”

“…Due to this reason, the mechanical property data for such biocomposites have been reported only in few papers; however, these results are encouraging. For example, Chen et al [883] performed nanoindentation tests on biocomposite coatings to give hardness and Young's modulus values. They found that the higher the loading of nanotubes, the better the properties.…”

Biocomposites and hybrid biomaterials based on calcium orthophosphates

“…For example, Chen et al performed nano-indentation tests on biocomposite coatings to give hardness and Young's modulus values. 1079 They found that the higher the loading of the nanotubes, the better the mechanical properties. Namely, at 20 wt% loading, hardness was increased by ~43% and Young's modulus by ~21% over a single-phase HA coating.…”

Carbon Nanotubes in Bone Tissue Engineering

“…On the other hand, excellent mechanical and biological characteristics of CNTs suggest the chance of strengthening and toughening HAp, while keeping its bioactivity (White et al, 2007). Measurements on HAp-CNT composite coatings fabricated by laser surface alloying show increase in elastic modulus and hardness of HAp due to adding CNT (Chen et al, 2006). Scratching tests also indicate enhanced wear resistance and lower friction coefficient as a result of raising the amount of CNTs in the composite (Chen et al, 2007).…”