Çağatay Kadir Aktaş, 030060176, 8th week

Fracture Mechanics: (13:24 5.4.2011)
Fracture mechanics is the study of mechanical behavior of cracked materials subjected to an applied load. In fact, Irwin developed the field of fracture mechanics using the early work of Inglis, Griggith and Wester gaard. Essentally, fracture mechanincs deals with the irreversible process of rupture due to nucleation and growth of cracks. The information of cracks may be a complex fracture process, which strongly depends on the microstructure of a partcular crystalline or amorphous solid, applied loading and enviorement. The microstructure plays a very important role in a fracture process due to dislocation motion, precipitates, inclusions,grain size and type of phases making up the microstructure. All these microstructural feature are imperfections and can act as fracture nuclei under unfavorable conditions.
(Nestor Perez, Fraction Mechanics, pg: 25)

Pressure Casting: (13:40 5.4.2011)
Molten metal is injected under pressure into a hardened steel die, usually watercooled. Metal cores are used to produce cavities and undercuts. AFter solidification, one half of the die is moved and the casting is pushed out by ejector pins. This process is suitable for non-ferrous castings of small to medium size, varying complexity and thin walls.
(B. Ravi, Metal Casting: Computer-Aided Design and Analysis, pg:8)

Squeeze Casting: (13:46 5.4.2011)
In these processes, solid metal is forced nder pressure in to a metal mould, giving a fine microstructure free from dendrites(tree like structures) otherwise obtained in conventional casting processes. The mechanical properties of the castings approach those of forging. These are useful for non-ferrous metals and composites and are applied for aerospace and automotive parts.
(B. Ravi, Metal Casting: Computer-Aided Design and Analysis, pg:8)

Ion Plating: (13:51 5.4.2011)
Ion plating is another surface treatment process that has recently attracted a great deal of attention. Ion plating also possesses many advantages as compared to conventional coating techniques. Therefore, although the present study has concentrated on ion implantation, it is appropriate to compare this proces with ion plating There are also striking diferences. Thusi each method is likely to find its own regime of application.

Ion plating is carried out in a gaseous electrical discharge in which the substrate to be plated is the cathode. The discharge is created by an applied ptential of 500 to 5000 volts. The prmary component of the gaseous enviroment is usually an inert gas, most often argon. Atoms of material to be plated are introduced into the gas by evaporation are ionized before striking the substrate. The small protion og evaporant are drawn to cathode by the electric field and scattering effects. Deposition rates can approach 25micrometer/min, but are acoomonly about a tenth of this amount.
(National Research Council (U.S.), Committee on Ion Implantation and Competing New Surface Treatmen Technologies Robert Wiliam Keyes, Ion Implatation as a New Surface Treatment Technolohy: Report, pg:19)