Bioactive coating on 321AISI stainless steel alloy and used for biomedical Implants

Bioactive coating on composite implants facilitates biological fixation between the prosthesis and the hard tissue, and increases the long-term stability and integrity of the implants. It produces an intermediate region between bone and implant. Hydroxyapatite coating Ca10 (PO4)6(OH)2 was carried out on stainless steel 321 AISI substrate by chemical method, this coating can forms strong chemical bonds with bone in vivo because it has the same mineral component of bone. The x-ray diffraction (XRD) technique were employed to investigate formed phases on the specimen surface. The coating formed is pure hydroxyapatite free from other phases like trior tetra calcium phosphate. Bioactive coating on 321AISI stainless steel alloy and used for biomedical ... 53 Electrochemical study involving cyclic polarization experiment was carried out to assess the corrosion resistance behaviour of Hydroxyapatite coated 321 SS comparing with uncoated specimen in Ringer's solution. The results of cyclic polarization have indicated the efficiency of coated specimen which showed high stability Compared with the uncoated specimen. Introduction: Hydroxyapatite (HAP) was first identified as being the mineral component of bone. However it was not until about 25 years ago that synthetic hydroxyapatite was accepted as a potential biomaterial for use in orthopedics, bone grafts and dentistry. It is one of a limited number of materials that forms strong chemical bonds with bone in vivo, while remaining stable under the harsh conditions encountered in the human body. These properties place hydroxyapatite into the class of biomaterials known as surface active or bioactive materials. We can define the term “biomaterial” as a synthetic material that is in contact with the human tissue and that does not cause a toxic response within the body as a consequence of its presence. The use of nonbiological materials as surgical implants is not new and especially the substitution of bone parts in the human body have been reported for centuries (H. Ohgushi et al, 2000). Any biomaterials must have some key properties in order to be used in contact with human tissues, and, apart from the specifications for its particular application, it has to be noncarcinogenic, must have a good resistance to corrosion and to wear, and finally the products of corrosion must be less toxic as possible (D.F. Williams, 1996). 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 bone (N. Ramesh Babu et al, 2004). Calcium phosphate coatings especially hydroxyapatite are used clinically on joint replacements and the main goal is to accelerate bone ingrowth to implant surface and thus fixation of the prosthesis. At the material level, bone is composed of organic and inorganic components. The organic part is 90% type collagen and the inorganic part is mainly hydroxyapatite with a small percentage of other ions such as carbonate, magnesium and fluoride etc.. Synthetic hydroxyapatite has been used for bone replacement and augmentation due its excellent biocompatibility and osteoconductive potential (D. Siva Rama Krishna et al, 2002) K. Prabakaran and S. Rajeswari, 2006 developed hydroxyapatite powder from fish bone through heat treatment method, and HAP developed from fishbone was electrophoretically deposited on type 316L SS and showed that the corrosion resistance behaviour of fish bone originated-HAP coated 316L SS is nobler than the pristine 316L SS. And