BTech-123

• Stainless Steels


  Highly alloyed steels that contain more than 10% chromium, characterized by their resistance to heat, oxidation and corrosion, used where corrosion resistance, durability, and minimum of maintenance is necessary
• Copper


  Ductile, malleable, nonmagnetic metal with a characteristic bright, reddish brown color, has the highest electrical and thermal conductivity of any substances except silver, useful alloys have enough strength for minor structural work, easily worked, attacked by alkalis and many of the common acids
• Copper


  • Highly resistant to corrosion by air and salt water, forms a surface layer of an insoluble green salt which retards further corrosion (patina)
• Copper is one of the best electrical conductors, finds tremendous use in the entire electrical field, from very fine wires to bus bars</b>
• Copper sheet and strip are used for roofing and flashing
• Tin


  Soft, ductile, malleable, bluish-white metal, normally covered with a thin film of stannic oxide which resists corrosion by air, moisture, sulfur dioxide, hydrogen sulfide, takes a highly reflective polish and has the ability to wet other metals
• The main use of tin is in metallic form of either pure tin or tin-containing alloys for protective coatings on stronger metals
• Architectural uses of tin include bronzes, brasses, terneplate, mirrors, gilding, solders, hardware and fusible alloys
• Zinc


  Medium hard, bluish-white metal, characterized by brittleness and low strength, readily attacked by acids and alkalis, resistant to corrosion by water, forms a protective film of zinc carbonate or oxide on exposure to air
• The most important uses of zinc are as protective coatings (galvanizing) on iron and steel, as die-casting metal, and as an alloying element in brasses
• Galvanizing is the process whereby a protective coat of zinc is applied to steel and iron to protect them against corrosion, the zinc corrodes and forms compounds which cover and continue to protect the iron or steel if it becomes exposed
• Zinc


  When exposed to air, a film of zinc carbonate or oxide forms which protects zinc from further oxidation
• Most important uses of zinc

  • As protective coatings (galvanizing) on iron and steel
  • As die-casting metal
  • As an alloying element in brasses
• Galvanizing


  The process whereby a protective coat of zinc is applied to steel and iron to protect them against corrosion
• The advantage of coating steel and iron with zinc is that, should the iron or steel become exposed through wear, aging or discontinuities, galvanic reaction between the coating and the base metal causes the zinc to corrode and form compounds which cover and continue to protect the iron and steel for as long as any zinc remains
• The most common galvanized material used in architecture is galvanized iron (steel) sheet and strip
• Galvanized sheets become defaced and discolored when subjected to dampness and extremes of temperature
• If the sheets are piled flat in the open or tightly bundled in a warehouse, the zinc coating can also be damaged by the consequent absence of oxygen and carbon dioxide between two sheets. This absence prevents the formation of a protective film of zinc carbonate; instead zinc hydroxide forms and destroys the galvanizing
• Brass


  Fundamentally an alloy of copper and zinc with small quantities of other elements sometimes added to give the special qualities
• Copper-zinc proportions in brass

  May vary from 95% copper and 5% zinc to 55% copper and 45% zinc
• As a class, brass alloys are less hard and strong than steels (iron-base alloys) but are superior in workability and resistance to corrosion
• All brasses react with other metals. When brass is used in direct contact with any other metal, a careful check should be made of its position on the galvanic series. Brass should not come into direct contact with iron, steel or stainless, aluminum, zinc or magnesium if there is an electrolyte present or the possibility of one forming at the point of contact
• Architectural uses of brass

  • Doors
  • Windows
  • Door and window frames
  • Ornamental metalwork such as railings, trims, grilles
  • Finish hardware
  • Plating of hardware
  • Miscellaneous accessories such as screws, nuts and bolts, anchors
• True bronze


  An alloy of copper and tin which varies only slightly from 90% copper and 10% tin composition
• True bronze is a rich golden-brown metal, originally worked by forging and particularly suited for casting since it is corrosion resistant, dense and hard enough to take an impression of a mold of any delicacy whatever
• The term "bronze" is no longer used in the limited sense of an alloy of copper and tin. In commercial practice the terms "brass" and "bronze" may be used without much regard for their original meanings
• The term "bronze" now usually has a prefix and indicates alloys of copper with silicon, manganese, aluminum, and other elements with or without zinc, e.g. silicon bronze
• A few brasses are known as bronzes because they have the characteristic bronze color
• Of the three types of so-called bronzes in architectural work, only one is true bronze. This is the statuary bronze, which consist usually of 97% copper, 2% tin and 1% zinc
• Architectural bronze is really a leaded brass, and commercial bronze is one of the more commonly used brasses (90% copper and 10% zinc)
• The architectural uses of bronze are confined to statuary, plaques, medallions and other ornamentation, and miscellaneous rough and finish hardware
• Chromium


  A steel-white metal which takes a brilliant polish and is harder than cobalt or nickel. It is nonmagnetic at ordinary temperatures but becomes magnetic at 13F. It does not tarnish in air, resists oxidizing agents, is soluble in acids and strong alkalis
• Principal uses of chromium

  • As an alloying ingredient in ferrous and nonferrous metallurgy
  • Chromium plating
• Chromium plating gives a thin, hard, bright, wear resistant surface which sheds water when highly polished. The metals that can be plated with chromium include aluminum, copper, iron, magnesium, nickel, titanium, zinc and their alloys. The chromium is electro deposited as a thin layer of pure metal
• Nickel


  An inert silvery metal that is resistant to strong alkalis and to most acids. It resembles iron in strength and toughness and copper in its resistance to oxidation and corrosion. Nickel takes a high polish and can be hot and cold rolled forged, bent, extruded, spun, punched and drawn
• When alloyed with other metals, nickel imparts its qualities of strength, hardness, toughness, ductility, corrosion resistance, and strength at high temperatures to the resulting material. The major use of nickel therefore is in alloys
• Another important use of nickel is as protective or decorative coating for other metals. It can be applied to the following base metals and their alloys: aluminum, brass, copper, iron, magnesium, steel, tin, and zinc
• Lead


  A blue-gray, soft, very heavy metal (the heaviest of the common metals). It is extremely workable, has good corrosion resistance, is easily recovered from scrap materials, and is relatively impenetrable to radiation. The corrosion resistance of lead arises from the fact that metallic lead does not react with many compounds or solutions, and with
• Nickel


  Major use is in alloys
• Nickel


  Another important use is as protective or decorative coating for other metals