Abstract
Silver-bio nanocomposite coating on stainless steel (316L) sheets was prepared by electroless deposition technique. The bath composition influences on the characteristics of Ag based Multi wall carbon nanotube(MWCNTs), Hydroxyapatite (HA) and Alumina (Al2O3) bio nanocomposite coating produced by electroless deposition technique,The variable of this process are (Temperature ,Speed ,pH ,Concentrations) therefore, the present work aims to comparing the influences of the Multi-wall carbon nanotube (MWCNTs) ,Hydroxyapatite(HA), and Alumina (Al2O3 )nanoparticles incorporation at various concentrations (0.1, 0.3 and 0.5)g/l on the mechanical property (microhardness) , chemical properties (corrosion resistance and ion release) , surface morphology and crystal structure of Ag- nanocomposite coatings as well as biological property( anti-bacterial property) for the coated substrate ,The application of this work in orthopedic and dental devices,stent .
From the EDS results, it’s obvious that the nanocomposite coatings comprise a silver matrix with (MWCNTs, HA and Al2O3) strengthening nanoparticles.
The scanning electron microscope (SEM) analysis results showed that the coatings are uniform and covers the stainless steel (316L) substrate, and showed that the uniform distribution of nano particles in the Ag matrix coating.
While X-ray diffraction(XRD) results, showed that the nanocomposite coatings Ag- (, Hexagonal-MWCNT, HA and Alpha-Al2O3) being nano-crystalline structures.
The microhardness tests outcomes manifested an important enhancement in the property of the hardness of (Ag- MWCNTs), (Ag-HA) , (Ag- Al2O3) with increasing the concentration of nano particles, Which it is compared with stainless steel 316L without coating (104.6 Hv). Where, the ( Ag-0.5 MWCNTs) nanocomposite coatingoverhead registered the uppermost values (204.9 Hv) in comparison with HA and Al2O3 nanocomposite coating.
The corrosion rate ( by Tafel extrapolation method) of the coated specimen by (Ag–0.5MWCNT) nano-composite coating possess lower rate of corrosion (1.083× 10-1 mpy ), It is less than the rate of the corrosion of uncoated Stainless steel( 316 L) (6.313×10-1 mpy).
The ions release for the coated substrate (Ag-0.5 MWCNTs, Ag-0.5 HA, Ag-0.5 Al2O3) nanocomposite coatings of two elements ( Ni ,Cr) in the tests of immersion sample in Ringer solution .The release of Ni was obtained about (0.17-0.26) % within the allowable limit in accordance with the amount of Ni permitted to be inside the human body. The ions for chromium weren’t released owing to a passive film shaped upon the surface of the samples.
The anti-bacterial evaluated for the coated substrate via electroless 0.5 (Ag-MWCNTs ,Ag-HA andAg-Al2O3) bio nano composite coatings that immersed in E. coli (gram-negative) bacteria results are show the clear zone formation around the disc denotes bacterial inhibition. Where was the best rate of killing bacteria in Ag-0.5 MWCNTs, which about (13mm). The difference in the killing area for bacteria was small and close, and the killing rate for bacteria was good. This indicates the good effectiveness of silver towards killing bacteria.
