A Review: Bio-compatible Thermal Spray Coating on Bio-implant

In biomedical engineering, the repairing of hard tissues/bones has always been a vital issue. The excellent balance between the mechanical and physical–chemical properties recorded can be achieved by Titanium and its alloys so they are recognized as the best materials for bio-implant. Although titanium is the best material for loading applications, the durability of titanium is much higher than actual bones. In addition to the chemical conjugation of titanium and its alloys, which is an attractive feature of the body’s changing biological environment, it results in many immune eruptions and implant reactions. Hydroxyapatite, a calcium phosphate biomaterial, has been developed as a bio-implant ingredient in osteoporosis and dentistry due to its osteoconductive and osteoinductive properties. Hydroxyapatite mechanical properties such as brittleness and low fracture softness limit its load to small deposits under low load conditions. To achieve the desired mechanical strength and similar harmonic properties, the researchers designated the addition of metals with the hydroxyapatite mixture on top of them. Thermal spraying techniques are a revolutionary implant technique that uses thick layers of bio-adhesive materials to enhance their biocompatibility in bio-implants. In modern cases, alternative methods for thermal sprayings, such as Plasma spray, High Velocity Oxy-Fuel spray, and cold spraying, are widely used in bio-implant coatings. This article is a review of some previous works in the fields of bio-implants as well as the devising and optimization of thermal spray coatings.