TEM Studies Of HA Coating On Titanium Substrate And Synthesize Carbon Nanotubes On A Large Scale

Precipitation of hydroxyapatite on titanium substrate from aqueous solution offers the possibility of creating bioactive coatings for bone-fixated implants by mimicking the physiological properties of the bone. Layered structure has been found (or could be deduced) upon the TEM observations from both cross section view and plane view specimens. The layers from substrate to top of the deposited film are Ti substrate, buffer layer (interface between substrate and film), porous layer and lamellar layer. SAED (Selected area electron diffraction), HREM (High resolution electron microscopy) and EDS (Energy dispersive spectrum) experiments confirmed that both the porous layer and lamellar layer are composed of nano-crystalline HA (hydroxyapatite). The grain size of the porous layer is about 2nm and the thickness lamellar layer is a few tens of nanometer.It is very important to produce carbon nanotubes on large scale with a relative low cast for their potential applications. Three methods are expatiated: "floating catalyst", "catalyst driven by gases " and "ferrocene vaporizing " in second part of this paper. "Floating catalyst" and "catalyst driven by gases" method can synthesize powder of carbon nanotubes on large scale. "Vaporizing ferrocene" method can synthesize bulk carbon nanotube array. The production of the first method is 2000g/day, the second one is 500g/day and the third one is lOOg/day. The length of carbon nanotubes ranges from 5 to 30 microns. The purity of the CNTs is 75% for the first and second method and 90% for the third one respectively.