A flow process that governs the movement of atoms and molecules in solids is called diffusion. The atoms and molecules change their position under influence of thermal energy, stress gradient, electric and magnetic field gradients, and concentration gradient. The process of diffusion can be easily visualized in a liquid but is more difficult to see …
Loss due to corrosion has been estimated to be about 3% of annual income of an industrially advanced country. To prevent this huge loss, various methods are adopted to protect metals from corrosion. Important amongst these are Use of noble metals. Use of corrosion and oxidation resistant materials. Use of protective coatings. Use of inhibitors. …
The destruction of metals by chemical or electro-chemical reactions with the environment is called as corrosion. Freedom of valence electrons and their conduction is responsible for corrosion in metals. Gold and platinum, the noble metals, do not corrode as they are most inactive. Products of corrosion are either porous or non-porous. These products interfere in …
Separation of a solid into two or more parts under applied load or stress is called fracture. Depending on the type of load, fracture may be termed as tensile fracture, compressive fracture, shear fracture, fatigue fracture, creep fracture and cleavage fracture etc. However, these fractures are mainly characterized by either a Ductile fracture, or Brittle …
Composite material is a material system composed of two or more dissimilar constituents, differing in forms, insoluble in each other, physically distinct and chemically inhomogeneous. The resulting product possesses properties much different from the properties of constituent materials. Classification of Composite Materials Composite materials, also referred as composites, are broadly classified as Agglomerated composite materials, …
Materials derived from carbon are termed as organic materials. Range of organic materials is in thousands owing to vast variety of hydrocarbons and their derivatives. Organic materials may be natural or synthetic. Petroleum rubber wood coal biological fibers food etc. cotton flax are examples of natural organic materials. And oil solvent lubricant adhesive dye synthetic …
Ceramics are nonmetallic, inorganic, amorphous solids and are mostly metallic oxides. They have poor tensile strength, and are brittle. They can be either crystalline or noncrystalline. Many ceramics are workable in extremely low (cryogenic) temperature range, while many others are able to sustain high temperatures. Silica, silicates, NaCI, rock salt, MgO, CaF2, glasses, CsCl etc. …
In this article I will discuss chemical heat treatment processes. These are: 1. Case Hardening Process (or carburising) solid or pack carburising liquid carburising, and gaseous carburizing. 2. Cyniding 3. Nitriding 4. Carbo-nitriding 5. Flame hardening 6. Induction hardening All other heat treatment processes are discussed in the preceding article. This article is next part …
The properties of metals and alloys can be changed by heating followed by cooling under definite conditions to make them suitable for specific applications. Accordingly steel can be hardened to resist cutting action and prevent abrasion. The rate of cooling and the manner of cooling are the controlling factors in heat treatment processes. Heat treatment …
Carbon steels (or plain carbon steels) are ferrous metals. Percentage of carbon in them varies from about 0.05% to 2%. Accordingly they are classified as mild steel, medium carbon steel and high carbon steel. Mild steel is soft, medium carbon steel is tough, and high carbon steel is hard in comparison to each other. Following …