JMS_V4_N1_RevP1 Fasil Gessesew Beyene Journal on Material Science 2347–615X 4 1 32 40 Nanocoating, Hardness, Toughness, Subtrate Sol-Gel Nanocoatings are one of the most important topics within the range of nanotechnology. Through nanoscale engineering of surfaces and layers, a vast range of functionalities and new physical effects can be achieved. Some application ranges of nanolayers and coatings include Wear protection, Anti-graffiti, Anti-fouling, Corrosion protection, Biocompatible implants, Ultrathin die electrics, Better catalytic efficiency, Photo and electro chromatic windows, etc. Nanocoating on metallic surfaces can be applied using Six Synthesis technique Method. Mechanical properties of metals which are related to plastic deformation are yield strength, tensile strength, ductility, toughness and hardness. A requirement for almost all engineering structural materials is that they are both strong and tough (damage tolerant) yet invariably, in most materials, the properties of strength and toughness are mutually exclusive. It is the lower-strength, and hence higher-toughness, materials that find use for most safety-critical applications where premature or, worse still, catastrophic fracture is unacceptable. For these reasons, the development of strong and tough (damage-tolerant) materials has traditionally been an exercise in compromise between hardness versus ductility. There have been a lot of researches in nanocaoting that improve toughness and hardness, but there is a limitation in improving toughness without affecting its minimum hardness. This paper presents a review on those methods and mechanisms. April - June 2016 Copyright © 2016 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=5985