- مبلغ: ۸۶,۰۰۰ تومان
- مبلغ: ۹۱,۰۰۰ تومان
Bioactive coatings on metallic implants facilitate joining between the prosthesis and the osseous tissue, and increase the long-term stability and integrity of the implant. Literature suggests that current coating techniques provide inadequate adherence of the coating to the implants. A processing schedule was developed that minimizes reactions and produces thin coatings with the substrate. Hydroxyapatite and biphasic calcium phosphate (combination of hydroxyapatite and tri-calcium phosphate) coatings were carried out on 316L stainless steel implant material by a simple dip-coating method. Prior to the coating the substrate surfaces were passivated. The dip-coated implant materials were subsequently heat treated at appropriate temperatures for improving coating adhesion to the substrate. The coated implant materials have been characterized by X-ray diffraction, scanning electron microscopy and adhesion test. The results show that the dip coated hydroxyapatite and biphasic coatings of thickness of about 5-7 micron strongly attach to the 316L stainless steel substrates.
Bioactive hydroxyapatite has a substantial interest because of its chemical similarity to the calcium phosphate minerals in biological hard tissue, and its ability to form a strong chemical bond with bone1. But the fracture toughness of the hydroxyapatite ceramics does not exceed the value of about 1 Mpa.m1/2. Therefore, the hydroxyapatite ceramic materials cannot be used as heavy-loaded implants, such as artificial bone or teeth. Metallic implants (316L stainless steel, titanium, Ti-6Al-4V, etc.) are having high strength and fracture toughness, but their bonding ability to bone tissue is very low. In order to obtain bioactive and strong materials, the formation of hydroxyaptite on an implant with good mechanical properties is considered a good approach. Biphasic calcium phosphate coating is preferred when implant resorbability is desired.
a) Dip coating is a simple method to produce hydroxyapatite or biphasic calcium phosphate coating on stainless steel substrates.
b) The dense, fracture free coating can improve adhesion with the substrate and also acts as barrier layer between implant surface and body fluids.
c) By dip-coating method, its possible to obtain a very thin coating of thickness 5-10 (m for both hydroxyapatite and biphasic calcium phosphate coatings on 316L stainless steel.