tailieunhanh - Ebook Engineering materials (2nd edition - Volume 1): Part 2

(BQ) Part 2 book "Engineering materials" has contents: Creep deformation and fracture, oxidation and corrosion; friction, abrasion and wear; materials and energy in car design; case studies in friction and wear; wet corrosion of materials,. and other contents. | E. Creep deformation and fracture Chapter 17 Creep and creep fracture Introduction So far we have concentrated on mechanical properties at room temperature. Many structures - particularly those associated with energy conversion, like turbines, reactors, steam and chemical plant - operate at much higher temperatures. At room temperature, most metals and ceramics deform in a way which depends on stress but which, for practical purposes, is independent of time: E = f (a)elastidplastic solid. As the temperature is raised, loads which give no permanent deformation at room temperature cause materials to c r e q . Creep is slow, continuous deformation with time: Ceramics 0 F . . Melting or softening temperature. i g Metals Polvmers Commites 170 Engineering Materials 1 the strain, instead of depending only on the stress, now depends on temperature and time as well: E = f(a,t, T ) creeping solid. It is common to refer to the former behaviour as ’low-temperature’ behaviour, and the latter as ’high-temperature’. But what is a ‘low’ temperature and what is a ’high’ temperature? Tungsten, used for lamp filaments, has a very high melting point - well over 3000°C. Room temperature, for tungsten, is a very low temperature. If made hot enough, however, tungsten will creep - that is the reason that lamps ultimately burn out. Tungsten lamps run at about 2000°C - this, for tungsten, is a high temperature. If you examine a lamp filament which has failed, you will see that it has sagged under its own weight until the turns of the coil have touched - that is, it has deformed by creep. Figure and Table give melting points for metals and ceramics and softening temperatures for polymers. Most metals and ceramics have high melting points and, because of this, they start to creep only at temperatures well above room temperature Table Melting or softening(s) temperature Diamond, graphite Tungsten alloys Tantalum alloys Silicon carbide, Sic Magnesia, .

• Cơ khí - Chế tạo máy
• Engineering materials
• Creep deformation
• Oxidation and corrosion
• Abrasion and wear
• Energy in car design
• Wet corrosion of materials
• Materials for engineering
• Organic polymeric materials
• Composite materials
• Conversion factors
• Cellular solids
• Building materials in civil engineering
• Building materials
• Civil engineering
• Construction steel
• Waterproof materials
• Building plastic
• Sound absorbing materials
• Air hardening binding materials
• Portland cement
• Workability of fresh concrete
• Determination of mechanical properties
• Mechanical properties
• Engineering alloys
• Handbook of mechanical engineering
• mechanical engineering
• mechanical design
• mechanical materials
• alloy materials
• Energy Technology
• Materials science and engineering
• Materials science
• Properties of ceramics
• Polymer structures
• Degradation of materials
• Electrical properties
• Thermal properties
• Optical properties
• Principles of electronic materials
• Electronic materials
• Principles electronic
• Electrical engineering
• Engineering physics departments
• Modern physical metallurgy
• Materials engineering
• Mechanical behaviour of materials
• Strengthening and toughening
• Modern alloy developments
• Surface engineering
• The structure
• Atomic arrangements in materials
• Defects in solids
• The characterization of materials
• Processing and DesignMichael
• DesignMichael Ashby
• Processing
• Materials Engineering Science