For decades, the standard metallic materials for hip implants, besides the
316LVM stainless steel, were titanium- and cobalt/chromium-based alloys.
Although bioinert, due to their corrosion resistance, they are not
biocompatible. Contemporary surgical implants are not made just of bioinert
metal anymore, but with deposited bioactive hydroxyapatite (HAp) coating.
Hydroxyapatite is chemically identical with the mineral constituent of bones
and teeth, what besides its biocompatibility provides bioactivity as well.
The HAp limitations are, however, weak tensile strength and low fatigue
resistance for long term loadings, if used alone. This is the reason for HAp
to be deposited onto the surgical implant, and to enable its bioactivity,
what means intergrowth with bones, and therefore the long-lasting and
mechanical stable non-cemented prosthesis. This is important predominantly
because the need for such prostheses for younger population, and a better
life quality. There are several contemporary techniques that have been used
for deposition of these coatings onto the metal implant. The possibilities of
atmospheric plasma-spraying for obtaining the stable HAp coatings on the
316LVM stainless steel, ordinary used as a standard material for hip implants
production are presented in this paper. The coatings of a commercially
available hydroxyapatite powder were plasma-sprayed onto the specimens of
medical grade 316LVM stainless steel under various operating conditions. The
optical microscopy was used for microstructure and porosity characterization,
while coating morphology and Ca/P ratio were analyzed using SEM equipped with
EDX. Coating microstructure varied from a porous to a glassy structure,
depending on operating conditions applied and coating thickness. Coating
porosity was determined to be at the lower required limit requested for the
bone-coating intergrowth possibility, but nevertheless adhesion measurements
showed good results. The Ca/P ratio was determined for both as-deposited
coatings and after ageing in distilled water for various time and temperature
combination.
Investigations of microstructure and selected mechanical properties of Al2O3 + 40 wt.% TiO2 coatings deposited by Atmospheric Plasma Spraying (APS)
