Evaluation of Ti/Al alloy coated with biogenic hydroxyapatite as an implant device in dogs' femur bones.

The main target of the present research was a full assessment of the toxicity effects and biocompatibility of a Ti/Al-alloy device coated with biogenic hydroxyapatite (bHA) when implanted in dogs in comparison with those of an uncoated Ti/Al-alloy device. The coating of the alloy was carried out using controlled high-velocity suspension flame spray (HVSFS) technique. Both coated and uncoated devices were implanted in dogs' femur bones for different time periods (45 days and 90 days). Bone-formation ability and healing were followed up, and blood analysis was performed, at Time zero (immediately post surgery), and then at 3 days, 45 days, and 90 days post surgery. Bone mineral density checks, radiological scans of the femur bone, and histological analysis were also conducted. The in-vivo study results proved that implantation of a device made from bHA-coated Ti/Al alloy in dogs' femur bones is completely safe. This is due to the high osteoconductivity of the coated alloy, which enables the formation of new bone and a full connection between new and original bone material. At 90 days post surgery, the coated alloy had been completely digested within the original bone; thus, it appeared as a part of the femur bone and not as a foreign body. Both the scanning electron microscopy with energy-dispersive X-ray and histology analysis findings affirmed the results. Furthermore, the blood tests indicated no toxicity effects during the 90 days of implantation.

Manufacturing parameter analysis for alumina coating on steel substrate by automated image processing of isolated splats samples.

Thermal spray technology, which involves the Atmospheric Plasma Spraying (APS), encompasses a category of coating processes that supply surface properties to protect or improve the performance of a substrate or component. The coating produced by this technology is built by overlapped splats, whose morphology determines the coating properties. In the same way, the splats obtained in a separated distribution by interposing a perforated mask but using the same thermal spray parameters, has a relationship with the overlapped splats inside the coating. The samples with isolated splats have the advantage of being faster and cheaper to generate and analyse. This article analyses alumina plasma-sprayed splats on steel substrates by image processing techniques, which recognize individual splats and their corresponding morphology (doughnut and pancake) parameters. These parameters allow the user to efficiently classify the splats. After that classification, a quality control can be implemented by comparison between the original and checked sample of isolated splats and a new sample obtained during a small interruption in the normal operation. Additionally, these parameters obtained in an automated way can be used to evaluate the effect of different selections of spraying process parameters.

High velocity suspension flame spraying (HVSFS) of metal doped bioceramic coatings.

•Bioceramic coatings doped with metals for antibacterial effect.•Combination of suspension and precursor flame spraying.•Successful deposition of submicron metallic particles in bioceramic matrix.

Microstructure and in vitro behaviour of 45S5 bioglass coatings deposited by high velocity suspension flame spraying (HVSFS).

The high-velocity suspension flame spraying technique (HVSFS) was employed in order to deposit 45S5 bioactive glass coatings onto titanium substrates, using a suspension of micron-sized glass powders dispersed in a water + isopropanol mixture as feedstock. By modifying the process parameters, five coatings with different thickness and porosity were obtained. The coatings were entirely glassy but exhibited a through-thickness microstructural gradient, as the deposition mechanisms of the glass droplets changed at every torch cycle because of the increase in the system temperature during spraying. After soaking in simulated body fluid, all of the coatings were soon covered by a layer of hydroxyapatite; furthermore, the coatings exhibited no cytotoxicity and human osteosarcoma cells could adhere and proliferate well onto their surfaces. HVSFS-deposited 45S5 bioglass coatings are therefore highly bioactive and have potentials as replacement of conventional hydroxyapatite in order to favour osseointegration of dental and prosthetic implants.