Coated Metal: Structure and Properties of Metal-Coating Compositions (Engineering Materials)

Saving in metal, corrosion and wear control of machine parts are the problems of increasing priority. Conventional constructional materials are unable to provide re­ liability and durability of equipment under conditions of increased working speeds and loads, aggressive medium attacks and elevated temperatures. Solution to these problems involves change in properties of the surface layers of products, in the first instance, by means of depositing functional coatings on machine parts. Rela­ tive simplicity of the process and. practically unlimited possibilities of varying properties of coatings have resulted in their wide usage in machine building and transport industry, instrument engineering, radio electronics and other industries. Coating provides means for enhancing constructional strength of steels and al­ loysl. It makes possible a combined method when one group of dislocation mechanisms is used for bulk hardening (grain refining, creation of stable sub­ granular dislocation structures), while the working surface is hardened through other mechanisms (dislocation density increase, separation of excess phases, etc). Combined hardening saves valuable alloying components and provides reduction in metal consumption of machines and constructions. Coating allows manufacturing new composites that combine high durability (fatigue resistance, wear resistance) with sufficient reliability (fracture toughness); enhancement of operational stability of machine parts and tools as compared to stability attainable using conventional heat treatment methods; restoration of worn surfaces and, consequently, reduction in demand for spare parts. The spread of modern coating technology is impeded by the slow development of the special methods of evaluating their stucture and properties. Most publications consider only the technological aspects of the modern coating methods. This, combined with a lack of a well-grounded scientific analysis of the investigation results, not only thwarts the possibility for improving the coating modes, but also can compromise a clearly progressive technology. This book can be viewed as a scientific investigation combined with methodological studies. For practical reasons each of the methods is described in the following general manner including: the uses and the scientific investigation tasks; methods of sampling; testing equipment; test preparation; tests; data processing; controversial issues and conclusions. Each of the 37 methods contains a range of 1 to 8 variants. As far as we know, the book is the first publication in the field. Front Matter....Pages I-XVIII Structure....Pages 1-84 Mechanical Properties of Coatings....Pages 85-131 Physical Properties of Coatings....Pages 133-204 Investigation of Protective Properties....Pages 205-249 Determination of Bond Strength Between a Coating and Base Metal....Pages 251-283 Wear Resistance of Coated Materials....Pages 285-361 Fatigue Failure of the Base Metal-Coating Composition....Pages 363-395 Breaking Strength and Stressed State of Base Metal-Coating Composition....Pages 397-438 Conclusions....Pages 439-440