Engineering 

How to Carryout Soldering of Zinc and Aluminium?

Soldering is the process of joining two or more similar or dissimilar pieces of metal by the application of low melting alloy (solder) and heat. The ease with which a metal can be soldered depends upon the characteristic of the oxide and mutual solubilities of the solder and base metal. When soldering zinc or zinc coated (galvanized) iron, care must be taken in the selection of solder, flux and also the temperature employed for the operation. The soldering of aluminium has always been surrounded by an atmosphere of mystery. It…

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Engineering 

How Changes Occur in the Crystal Structure of Metals?

Many materials such as iron, tin, zinc, nickel, cobalt, etc. undergo crystalline transformation in the solid state when there is a change in their temperature. They exist in one lattice form over a certain range of temperature, but at a somewhat higher or lower temperature, the lattice form changes to another lattice form, which is stable in that temperature range. Allotropy or Polymorphy An element that occurs in more than one crystallographic or lattice form is called allotropy or polymorphy, and the material in which such changes occur are known…

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Construction of Various Types of Direct Reading Compass

Direct Reading Compass The purpose of liquid compass is to indicate in which direction the magnetic north pole lies, to enable and ac position to be determine with respect to that pole. They are classified under two headings.  (a) Pilot Type. It is used to indicate the magnetic heading of the aircraft.  (b) Observer Type. It is used with adjustable sights to enable bearing to be taken of distant object (ac) Pilot Type. The magnetic compass is a simple, self-contained instrument, which operates on the principle of magnetic attraction. It is designed to indicate the direction in which…

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Physical Metallurgy & Structure of Solids – Covalent Solids

Solid materials are made up of large collection of atoms where the individual atoms are bonded together. The type of bonding which exists between atoms is different for all material. An atom with a completely filled outer electron shell has a high degree of stability. The atoms of other elements with incomplete outer shells attempts, by combination with other atoms, to satisfy this condition for stability. The principal types of inter atomic bonds which may be formed are the ionic, covalent, metallic, Van Der Wall’s or molecular bonds. The solids…

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Atomic Arrangement in Metals

A metal can exist in the gaseous, liquid or solid states depending upon the pressure and temperature. Metals have the ability to donate electrons and form a positive ion. Metals have high density, high melting temperature, good electrical and thermal conductivity, metallic lustre and crystalline structure. Structure of Solids – On the basis of structure, solids are broadly classified as: (a) Amorphous Solids. These are solids where the atoms making up the crystal are not arranged in a systematic order. Examples of amorphous solids are wood, plastic, glass, rubber etc. (b) Crystalline Solids.These…

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Deformation of Metals

Deformation is the change in dimension or forms of matter under the action of the applied forces. Deformation is caused either by the mechanical action of the external forces or by various physical and physio-chemical processes. Deformation may be permanent or temporary depending upon the type of deformation whether it is plastic or elastic. So metal deformation are of following two types:  (a)      Elastic deformation  (b)      Plastic deformation Elastic Deformation – The deformation is called elastic if the strain or deformation produced in the material corresponding to a given stress completely…

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Property Changes by Deformation

Due to the cold working of metals, there arise a large number of dislocation and distortions of planes. Cold working of metals or alloys increases the hardness, yield strength, ultimate strength and electrical resistance whereas the ductility and plasticity are decreased. Following are some important changes in properties in metals due to plastic deformation. Work (Strain) Hardening Strain hardening or work hardening is the phenomenon whereby a ductile metal becomes harder and stronger as it is plastically deformed. The temperature, at which deformation takes place is cold, relative to the…

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Effect of Alloying Metals

An alloy is a substance having metallic properties. Alloying is done by combining one metallic element with one or more metallic or non-metallic elements. In an alloy, the metallic or non-metallic elements do not exist or operate in distinct layers when solid. An alloy when solid may be composed of eutectic alloy or eutectoid, solid solution, chemical compounds with each other or with pure metals. Alloying is done by the following four methods Melting two metals separately and mixing them. Melting one of the metals having higher melting point than…

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Aluminium and its Alloys

The non-ferrous metals are those which contain a metal other than iron as their chief constituent. The non-ferrous metals are usually employed in industry due to the following characteristics: Easy to fabricate i.e., casting, rolling, forging, welding and machining, High resistance to corrosion, Very good electrical and thermal conductivity, Low weight and attractive appearance. The various non-ferrous metals used in engineering practice are aluminium, copper, lead, tin. Zinc, nickel etc, and their alloys. Aluminium The chief source of Aluminium is a clayey mineral called ‘Bauxite’, which is a hydrated aluminium…

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Engineering 

Titanium & Zirconium Alloys

Titanium is a chemical element with the symbol Ti and atomic number 22. Sometimes called the “space age metal”, it has a low density and is a strong, lustrous, corrosion-resistant (including sea water and chlorine) with a silver color. Titanium can be alloyed with Iron, Aluminium, Vanadium, and Molybdenum to produce strong lightweight alloys for aerospace (jet engines, missiles, and spacecraft), military, industrial process (chemicals and petro-chemicals, desalination plants, paper industry), automotive, orthopedic implants, and other applications Property A metallic element, Titanium is recognized for its high strength-to-weight ratio It…

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