Galvanization or galvanizing is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which the parts are coated by submerging them in a bath of hot, molten zinc.
Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO(OH), Fe(OH)3), and is typically associated with the corrosion of refined iron.
Hot-dip galvanization is a form of galvanization. It is the process of coating iron and steel with zinc, which alloys with the surface of the base metal when immersing the metal in a bath of molten zinc at a temperature of around 450 °C (842 °F). When exposed to the atmosphere, the pure zinc (Zn) reacts with oxygen (O2) to form zinc oxide (ZnO), which further reacts with carbon dioxide (CO2) to form zinc carbonate (ZnCO3), a usually dull grey, fairly strong material that protects the steel underneath from further corrosion in many circumstances. Galvanized steel is widely used in applications where corrosion resistance is needed without the cost of stainless steel, and is considered superior in terms of cost and life-cycle. It can be identified by the crystallization patterning on the surface (often called a "spangle").
Cathodic protection is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell. A simple method of protection connects the metal to be protected to a more easily corroded "sacrificial metal" to act as the anode. The sacrificial metal then corrodes instead of the protected metal. For structures such as long pipelines, where passive galvanic cathodic protection is not adequate, an external DC electrical power source is used to provide sufficient current.
Terne plate is a form of tinplate: a thin steel sheet coated with an alloy of lead and tin. The terne alloy was in the ratio of 10-20% tin and the remainder lead. The low tin content made it cheaper than other tinplates.
Anodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts.
Corrugated galvanised iron (CGI) or steel, colloquially corrugated iron, wriggly tin, pailing, corrugated sheet metal, zinc or custom orb / corro sheet (Australia) is a building material composed of sheets of hot-dip galvanised mild steel, cold-rolled to produce a linear ridged pattern in them. Although it is still popularly called "iron" in the UK, the material used is actually steel, and only the surviving vintage sheets may actually be made up of 100% iron. The corrugations increase the bending strength of the sheet in the direction perpendicular to the corrugations, but not parallel to them, because the steel must be stretched to bend perpendicular to the corrugations. Normally each sheet is manufactured longer in its strong direction.
A metal roof is a roofing system featuring metal pieces or tiles exhibiting corrosion resistance, impermeability to water, and long life. It is a component of the building envelope. The metal pieces may be a covering on a structural, non-waterproof roof, or they could be self-supporting sheets.
Sendzimir process is used to galvanize a steel strip by using a small amount of aluminum in the zinc bath and producing a coating with essentially no iron-zinc alloy. The process guarantees high resistance and durability characteristics. About 75% of hydrogen was needed in the original Sendzimir process but all the newer nonoxidizing methods of degreasing require only 7–15%.
Chromate conversion coating or alodine coating is a type of conversion coating used to passivate steel, aluminium, zinc, cadmium, copper, silver, titanium, magnesium, and tin alloys. The coating serves as a corrosion inhibitor, as a primer to improve the adherence of paints and adhesives, as a decorative finish, or to preserve electrical conductivity. It also provides some resistance to abrasion and light chemical attack on soft metals.
Sherardising is a process of galvanization of ferrous metal surfaces, also called vapour galvanising and dry galvanizing. The process is named after British metallurgist Sherard Osborn Cowper-Coles who invented and patented the method c. 1900. This process involves heating the steel parts up to c. 500 °C in a closed rotating drum that contains metallic zinc dust and possibly an inert filler, such as sand. At temperatures above 300 °C, zinc evaporates and diffuses into the steel substrate forming diffusion bonded Zn-Fe-phases.
The salt spray test is a standardized and popular corrosion test method, used to check corrosion resistance of materials and surface coatings. Usually, the materials to be tested are metallic and finished with a surface coating which is intended to provide a degree of corrosion protection to the underlying metal.
Aluminized steel is steel that has been plated with aluminium or aluminium-silicon alloy, in a process analogous to hot-dip galvanizing. The steel workpiece is immersed in molten aluminum to produce a tight metallic bond between the steel and coating. The product has a unique combination of properties possessed by neither steel alone nor aluminium alone. Aluminized steel is more resistant to corrosion than bare steel while retaining properties of steel, at temperature lower than the melting point of aluminum, 800 °C (1,470 °F). Common applications include heat exchangers in residential furnaces, commercial rooftop HVAC units, automotive mufflers, ovens, kitchen ranges, water heaters, fireplaces, barbecue burners, and baking pans. Aluminized steel transfers heat more effectively than bare steel. It often serves where galvanized steel might have been used historically, without galvanized steel's drawbacks.
Electrogalvanizing is a process in which a layer of zinc is bonded to steel in order to protect against corrosion. The process involves electroplating, running a current of electricity through a saline/zinc solution with a zinc anode and steel conductor. Such Zinc electroplating or Zinc alloy electroplating maintains a dominant position among other electroplating process options, based upon electroplated tonnage per annum. According to the International Zinc Association, more than 5 million tons are used yearly for both hot dip galvanizing and electroplating. The plating of zinc was developed at the beginning of the 20th century. At that time, the electrolyte was cyanide based. A significant innovation occurred in the 1960s, with the introduction of the first acid chloride based electrolyte. The 1980s saw a return to alkaline electrolytes, only this time, without the use of cyanide. The most commonly used electrogalvanized cold rolled steel is SECC, acronym of "Steel, Electrogalvanized, Cold-rolled, Commercial quality". Compared to hot dip galvanizing, electroplated zinc offers these significant advantages:
Galvannealed or galvanneal is the result from the processes of galvanizing followed by annealing of sheet steel.
Metals used for architectural purposes include lead, for water pipes, roofing, and windows; tin, formed into tinplate; zinc, copper and aluminium, in a range of applications including roofing and decoration; and iron, which has structural and other uses in the form of cast iron or wrought iron, or made into steel. Metal alloys used in building include bronze ; brass ; monel metal and nickel silver, mainly consisting of nickel and copper; and stainless steel, with important components of nickel and chromium.
Corrosion engineering is an engineering specialty that applies scientific, technical, engineering skills, and knowledge of natural laws and physical resources to design and implement materials, structures, devices, systems, and procedures to manage corrosion. From a holistic perspective, corrosion is the phenomenon of metals returning to the state they are found in nature. The driving force that causes metals to corrode is a consequence of their temporary existence in metallic form. To produce metals starting from naturally occurring minerals and ores, it is necessary to provide a certain amount of energy, e.g. Iron ore in a blast furnace. It is therefore thermodynamically inevitable that these metals when exposed to various environments would revert to their state found in nature. Corrosion and corrosion engineering thus involves a study of chemical kinetics, thermodynamics, electrochemistry and materials science.
Bethanization is a process patented by the Bethlehem Steel Company to protect steel from corrosion by plating it with zinc, a process similar to electrogalvanization. In advertising materials, Bethlehem Steel claimed the process was more effective than hot dip galvanization, the most common means of using zinc to protect steel.
According to EN 13523-0, a prepainted metal is a ‘metal on which a coating material has been applied by coil coating’. When applied onto the metallic substrate, the coating material forms a film possessing protective, decorative and/or other specific properties.
The Phenix Works is a steel working factory located in Flémalle-Haute, Liège, Belgium. The business was established in 1905 by Paul Borgnet and became part of SA Phenix Work in 1911. The works specialised in coated steels, such as galvanised, tin plate etc.
