Cold Gas Spray (CGS) technology has allowed the development of biofunctional composite coatings composed of 45S5 and Polyetheretherketone (PEEK). The combination of a bioactive glass material embedded in a biocompatible polymeric matrix becomes this new composite in an interesting material for orthopedic applications since meet the biomechanical and biological requirements of an artificial implant. In the present study, blends of bioactive glass 45S5 and PEEK powder with different granulometry and 45S5/PEEK ratio have been prepared. These mixtures of powders have been deposited onto PEEK substrates by CGS with the goal of incorporating a bioactive additive to the biocompatible polymer, which can improve the bone-implant interaction of PEEK. The deposition efficiency (DE) and thickness of the coatings have been evaluated and from the results obtained, it was possible to conclude that DE and coating thickness are significantly affected by the granulometry and by the 45S5/PEEK ratio of the blends. By Scanning Electron Microscopy (SEM) inspection, it was observed that the use of blends with high 45S5/PEEK ratio led to the deposition of coatings with high content of 45S5 particles embedded in the polymeric matrix. Finally, the friction behavior of the coatings was analyzed performing ball-on-disk tests and these experiments showed that the presence of glass particles has a beneficial role in the wear resistance of the coatings.

This study investigates the effect of composition on the antibacterial and antiviral properties of hydroxyapatite/titania composite coatings deposited by suspension plasma spraying. Hydroxyapatite is a bioceramic material used as a plasma-sprayed coating to promote osseointegration of femoral stems. TiO2 has promising photocatalytic activity and good efficiency in destroying bacteria, viral species, and parasites. Prior to coating, substrates were grit blasted, ultrasonically cleaned, and heated to enhance adhesion strength. The microstructure of the resulting coatings was then characterized using XRD and Raman spectroscopy. Test results indicated that SPS transformed Ti2O3 into TiO2 with mixed phases. Ti4O7 and Ti3O5 phases were also identified, which show photocatalytic activity due to oxygen vacancies. Antibacterial and antiviral tests were conducted as well.

Effect of different thickness of bio-medical coatings on the bone stress distribution near the hip implant- bone interface is very important factors for the bio-coated implant design and clinical application. However, in the traditional finite element analysis, the muscle forces have not been considered, which results in a difference between the original analysis models from the actual condition. In this study, the hip contact forces, as well as the associated muscle forces are imposed. Wollastonite coatings and titanium alloy (Ti6Al4V) for implants are used in the model, which is constructed through using SolidWorks software. The bone and coating stress distributions near the hip implant coated with different thickness from 50 to 250 µm are calculated and analyzed by means of finite element analysis by ANSYS WORKBENCH Software. After hip replacement, the von Mises stress distribution is similar to that before the total hip arthroplasty, whereas the corresponding results decrease obviously. Effect of coating thickness has an indistinct influence on the bone stress near the hip implant.

Infection of medical devices and treatment rooms can cause significant morbidity and mortality. Having antibacterial surfaces such as silver and copper coated areas reduces the risk of bacteria growth considerably. In the current study, wire arc spraying technique has been utilized to produce an ultra fine microstructure Antibacterial copper coating on stainless steel substrate. The chemical composition, microstructure, and surface morphology of copper coatings were characterized with X-ray diffraction (XRD) and scanning electron microscope. Determination of thickness and adhesion of the coating were investigated. The antibacterial property of copper coatings was analyzed by both gram negative Escherichia coli NCTC 10418 and gram positive Staphylococcus aureus NCTC 11047. The antibacterial performance of coatings was compared to stainless steel 316 and a micro grain structure of the commercially available copper. Results indicated that as-sprayed copper coatings have an excellent antibacterial behavior compared to stainless steel and micro grain copper which can be contributed to the fine grain size and existing of defects and micro pores in the microstructure.

Thermal spraying of suspensions containing particles of submicron or nano-size offers new possibilities in functional coating development and enables new application fields. Spraying of suspensions containing bioceramic materials by hypersonic flame spraying (HVSFS), result in coatings with a refined microstructure. A layer thickness ranging from 10 - 50 µm can be achieved. Thermally sprayed HAp coatings are widely used for various biomedical applications due to the fact that HAp is a bioactive, osteoconductive material capable of forming a direct and firm biological fixation with surrounding bone tissue. Bioceramic coatings (e.g. Hydroxyapatite HAp, Tricalcium Phosphate TCP or Bioglass) were thermally sprayed on Ti plates by high-velocity suspension flame spraying. The deposited coatings were mechanically characterized. The bond strength of the layer composites was analyzed by the pull-off method and compared for different spraying conditions.

Bioactive coatings are proven to enhance bone regeneration, implant integration and act as drug-delivery systems following bone replacement surgeries. Polycaprolactone (PCL) was used in this study as coating material due to its superior biocompatibility and biodegradability. Polymethyl-methacrylate (PMMA) was used as an additive in order to improve the flowability of the PCL powder. The processing technique used to obtain polymeric coatings was oxy-acetylene flame spraying. Seeing that biodegradable polymers were not thoroughly investigated in the past, a Design of Experiments (DoE) analysis was necessary in order to understand the effects of spraying parameters on coating characteristics (thickness, roughness, adhesion, wettability) and to be able to optimize the coating properties for specific requirements. The polymer matrix was sprayed onto titanium substrates. The statistical analysis was followed by FTIR spectroscopy, which showed that the coatings underwent little chemical degradation. Finally, biocompatibility tests showed that cells proliferated well on the flame sprayed polymer coatings, which confirms that the coating technique used did not affect the biological performance of the material.

The phenomena occurring after injection of water-ethanol suspension of fine hydroxyapatite powder are simulated numerically. The mathematical modeling starts with the calculation of the map of velocity and temperature of working plasma gases. The map is calculated by taking into account the evaporation of the liquids included in the suspension. The suspension is injected through a mechanical injector into the anode-nozzle of the SG-100 torch. The plasma was generated with the use of working gases composed of 45 slpm of Ar and 5 slpm of H 2 and with the electric power input of 30 kW. The initial droplets of suspension were supposed to be spherical with a diameter equal to that of the injector, i.e., 500 µm. The trajectory of suspension was calculated until the evaporation of liquids. Then, the simulation of the movement and heating of solid hydroxyapatite (HA) started. The HA powder was home synthesized and exhibited a bimodal size distribution with two maxima around 3 and 10 µm. The equations describing the momentum and heat transfer from hot gas to the solids took into account the small size of solid particles. In particular, the thermophoresis force, as well as, the drag coefficient modified for non-continuum effect were used in the calculation of the trajectory of small particles. Similarly, the non-continuum effect was considered in the calculation of heat transfer. The obtained trajectories were tentatively correlated with the microstructure of the suspension plasma sprayed HA coatings.