These inexpensive carabiners have an anodised aluminium surface that has been dyed and are made in many colors.

Anodising, or anodizing, is a technique used to coat the surface of a metal with an oxide layer. It may be used to increase corrosion resistance, increase wear resistance, allow dyeing or prepare the surface for other processes and coatings including paint. Anodization changes the microscopic texture of the surface and can change the crystal structure of the metal near the surface. The process derives its name from the fact that the part to be treated forms the anode portion of an electrical circuit in this electrolytic process. ImageMetadata File history File links Download high resolution version (1600x1200, 564 KB) File links The following pages link to this file: Carabiner Anodising ... ImageMetadata File history File links Download high resolution version (1600x1200, 564 KB) File links The following pages link to this file: Carabiner Anodising ... The word comes from the German expression Karabinerhaken. Yet German climbers would always call it shortly Karabiner. Note that, in German, Karabiner also means carbine (a short rifle). ... Corrosion is deterioration of intrinsic properties in a material due to reactions with its environment. ... Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... Diagram of a zinc anode in a galvanic cell. ... An electrical network or electrical circuit is an interconnection of analog electrical elements such as resistors, inductors, capacitors, diodes, switches and transistors. ... An electrolyte is a substance containing free ions which behaves as an electrically conductive medium. ...

Anodisation is frequently used to protect aluminium and titanium from abrasion and corrosion and to allow it to be dyed in a wide range of colors. General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Atomic mass 26. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Atomic mass 47. ... Abrasion on the palm of a right hand, shortly after falling Abrasions on elbow and lower arm, still healing. ... Corrosion is deterioration of intrinsic properties in a material due to reactions with its environment. ... A dye can generally be described as a coloured substance that has an affinity to the substrate to which it is being applied. ...

Anodized titanium

selected colors achievable through anodization of titanium[1]

Anodized titanium is used in a recent generation of dental implants. Anodizing generates a thicker layer of titanium dioxide (>1 µm and up to >2.5 µm compared with much less than 1 µm for un-anodized specimens) and a characteristic surface topography. It has been suggested that both of these parameters improve the performance—longevity, stability—of dental implants, but the technology is still new and there are not yet clear clinical data to support these claims. Image File history File links Ti-color-strip. ... Image File history File links Ti-color-strip. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Atomic mass 47. ... A dental implant is used in restorative dentistry. ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length. ...

Anodizing is also said to impart anti-galling properties on threaded components. Galling can occur when metal parts, such as the threads of nuts and bolts, are forced together and rubbing generates friction among the asperities (high spots) on the surface. ...

Anodizing titanium generates an array of different colors without dyes, for which it is sometimes used in art, costume jewelry and wedding rings.[2][3] The color formed is dependent on the thickness of the oxide (which is determined by the anodising voltage); it is caused by the interference of light reflecting off the oxide surface with light traveling through it and reflecting off the underlying metal surface. Titanium nitride coatings can also be formed, which have a brown or golden color and have the same wear and corrosion benefits as anodization. General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Atomic mass 47. ... Costume jewelry is jewelry that is made of less valuable materials, including base metals, glass, plastic, and synthetic stones, in place of more valuable materials such as precious metals and gems. ... A wedding ring or wedding band consists of a precious metal ring, usually worn on the base of the left ring finger – the fourth finger (with the thumb counted as the first finger) of the left hand. ... Interference of two circular waves - Wavelength (decreasing bottom to top) and Wave centers distance (increasing to the right). ... TiN coated drill Dark gray TiCN coating on a Gerber pocketknife Titanium nitride (TiN) is an extremely hard (~85 Rockwell C Hardness or ~2500 Vickers Hardness)1, ceramic material, often used as a coating on titanium alloy, steel, carbide, and aluminum components to improve the substrates surface properties. ...

Anodized niobium

This anodizes in a similar fashion to titanium with a range of attractive colors being formed by interference at different film thicknesses. Again the film thickness is dependent on the anodising voltage. Uses include jewelry and commemorative coins. General Name, Symbol, Number niobium, Nb, 41 Chemical series transition metals Group, Period, Block 5, 5, d Appearance gray metallic Atomic mass 92. ... Jewelry (the American spelling; spelled jewellery in Commonwealth English) consists of ornamental devices worn by persons, typically made with gems and precious metals. ... Commemorative coins are legally issued coins with a denomination that are not usually meant for circulation. ...

Anodized aluminium

Aluminum is anodized both to increase corrosion resistance and to allow dyeing.

While pure aluminum creates a natural oxidation layer its alloys are more prone to corrosion and are therefore annodized for corrosion resistance. Most aluminium aircraft parts including major components are anodised. Anodized aluminium can be found in many consumer products like mp3 players, flashlights, cookware, cameras, sporting goods, and many other products both for corrosion resistance and the ability to be dyed. An alloy is a combination, either in solution or compound, of two or more elements, at least one of which is a metal, and where the resultant material has metallic properties. ... A digital audio player (DAP) is a device that stores, organizes and plays digital music files. ... A high power torch Green flashlight Flashlight is also the NATO designation for the Yakovlev Yak-25 Soviet military jet. ... cast-iron iron enamel stainless steel The cooking pan is a type of food preparation utensil commonly found in the kitchen which includes many more specific cooking vessels such as saucepans and frying pans (or fry pans). ... A camera is a device used to capture images, usually photographs, either singly or in sequence such as with video cameras. ... Sports equipment includes any object used for sport or exercise. ...

The aluminium oxide coating is grown from and into the surface of the aluminium. Because of this it is not prone to peeling or cracking like organic coatings such as paint. In most consumer goods the dye is contained in the outermost portion of the Aluminium oxide layer. While highly wear resistant the anodized surface can still be worn. If wear and scratches are minor then the remaining oxide will continue to provide corrosion protection even if the dye is removed. Aluminium oxide is a chemical compound of aluminium and oxygen with the chemical formula Al2O3. ... This article does not cite its references or sources. ...

There are three major processes for aluminium anodization. Type I is Chromic Acid Anodization, Type II is Sulfuric Acid Anodization and Type III is hardcoat anodization.

Type I and Type II Anodization

Aluminium, when exposed to the atmosphere, forms a passive oxide layer, which provides moderate protection against corrosion. This layer is strongly adherent because it is chemically bound to the metal surface as compared to oxidation (corrosion) in steel, where rust puffs up and flakes off, constantly exposing new metal to corrosion. In its pure form aluminium self-passivates very effectively, but its alloys, especially 6000 series due to the magnesium content, are far more prone to atmospheric corrosion and therefore benefit from the protective quality of anodising. Corrosion is deterioration of intrinsic properties in a material due to reactions with its environment. ...

Before being treated, the aluminium, if wrought, is cleaned in either a hot soak cleaner or in a solvent bath and may be etched in sodium hydroxide (normally with added sodium gluconate), ammonium bifluoride or brightened in a mix of acids. Cast alloys are normally best just cleaned due to the presence of intermetallics unless they are a high purity alloy such as LM0.

In aluminium anodization, this aluminium oxide layer is made thicker by passing a DC current through a sulfuric acid solution, with the aluminium object serving as the anode (the positive electrode). The current releases hydrogen at the cathode (the negative electrode) and oxygen at the surface of the aluminium anode, creating a buildup of aluminium oxide. Anodizing at 12 V DC, a piece of aluminium with an area of 1 square decimeter (about 15.5 square inches) can consume roughly 1 ampere of current. In commercial applications the voltage used is more normally in the region of 15 to 21 V. Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ... Sulfuric acid (British English: sulphuric acid), H2SO4, is a strong mineral acid. ... This article is about the chemistry of hydrogen. ... Diagram of a copper cathode in a Daniells cell. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... A decimetre (symbol: dm, American spelling: decimeter) is a measurement of distance equal to ten centimetres or 1/10 metre. ... The square inch is an Imperial unit / U.S. customary unit (non-SI non-metric) of area, used in the United States. ...

Conditions such as acid concentration, solution temperature, and current must be controlled to allow the formation of a consistent oxide layer, which can be many times thicker than would otherwise be formed. This oxide layer increases both the hardness and the corrosion resistance of the aluminium surface. The oxide forms as microscopic hexagonal "pipe" crystals of corundum, each having a central hexagonal pore (which is also the reason that an anodized part can take on color in the dyeing process). The film thickness can range from under 5 micrometres on bright decorative work to over 25 micrometres for architectural applications. Corundum is a crystalline form of aluminum oxide and one of the rock-forming minerals. ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the size of a droplet of mist or fog. ...

The older Type I (chromic acid) method produces thinner, more opaque films that are softer, ductile, and to a degree self-healing. They are harder to dye and may be applied as a pretreatment before painting. The method of film formation is different from using sulfuric acid in that the voltage is ramped up through the process cycle. In chemistry, chromic acid is a hypothetical chromium (Cr) compound, yet to be isolated, that would have the formula H2CrO4. ...

Hardcoat anodising

Hardcoat anodising is an electrochemical process that yields an anodic oxide, integral to the aluminium part. The layer increases the resistance to corrosion, wear and friction (with use of lubricants because of its porous structure it keeps the lubricating film stronger than a smooth surface). For example the cylinders of a BMW modern aluminium V8 have no loose liner, instead the walls are hardcoated. It also increases the electrical and thermal insulation. This complicates a reboring operation (although not common, given the longevity of modern engines due to improved lubricants), as the hard coating must be restored if the block is rebored.

Like other forms of anodising (such as Type I Chromic Acid Anodising or Type II Sulfuric Acid Anodising), Hardcoat Anodising (also known as Type III) is produced by immersing the aluminium components into an electrolyte solution, it differs from the other by the possibility to make it up to 20 times thicker(0.008in).

The hardcoat layer is equivalent to one of the hardest materials on earth: ruby (Al2O3) in industrial terms hardness of 60 to 65 Rockwell on the C scale.

Its colour ranges from gray to dark brown.

Dyeing

The iPod Mini is dyed using anodisation.

Where appearance is important, the oxide surface can be dyed before the sealing stage, as the dye enters the pores in the oxide surface. The number of dye colors is almost endless; however, the colors produced tend to vary according to the base alloy. Though some may prefer lighter colors, in practice they may be difficult to produce on certain alloys such as high-silicon casting grades and 2000-series (with its high copper content). Another concern is the lightfastness of organic dyestuffs—some colours (reds and blues) are particularly prone to fading. Black dyes and gold produced by inorganic means (ferric ammonium oxalate) are more lightfast. Image File history File links IPod_mini. ... Image File history File links IPod_mini. ... This article or section does not cite its references or sources. ... Inorganic chemistry is the branch of chemistry concerned with the properties and reactions of inorganic compounds. ...

Alternatively, metal (usually tin) can be electrolytically deposited in the pores of the anodic coating to provide colors that are more lightfast. Metal dye colors range from pale champagne to black. Bronze shades are preferred for architectural use. General Name, Symbol, Number tin, Sn, 50 Chemical series poor metals Group, Period, Block 14, 5, p Appearance silvery lustrous gray Atomic mass 118. ... The color champagne is a name given for several pale shades of yellow or beige. ... Unlucky black cat. ... Assorted ancient Bronze castings found as part of a cache, probably intended for recycling. ... The Parthenon on top of the Acropolis, Athens, Greece Architecture (from Latin, architectura and ultimately from Greek, αρχιτεκτων, a master builder, from αρχι- chief, leader and τεκτων, builder, carpenter) is the art and science of designing buildings and structures. ...

Alternatively the color may be produced integral to the film. This is done during the anodizing process using organic acids mixed with the sulfuric electrolyte and a pulsed current. An organic acid is an organic compound that is an acid. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16 (VIA), 3 , p Density, Hardness 1960 kg/m3, 2 Appearance Lemon yellow at STP Atomic properties Atomic weight 32. ... An electrolyte is a substance containing free ions which behaves as an electrically conductive medium. ...

After dyeing, the surface is usually sealed by using hot water or steam, sometimes mixed with nickel acetate or other anti-bloom agents, to convert the oxide into its hydrated form. This reduces the porosity of the surface as the oxide swells. This also reduces or eliminates dye bleed out and can increase corrosion resistance. Sealing at 20 °C in nickel-cobalt salts, cold sealing, when the pores are closed by impregnation is also popular due to energy savings. Coatings sealed in this method are not suitable for adhesive bonding. Hydrates are compounds formed by the union of water with some other substance, generally forming a neutral body, as certain crystallized salts. ...

Mechanical considerations

Anodising will raise the surface, since the oxide created occupies more space than the base metal converted. This will generally not be of consequence except in the case of small holes threaded to accept screws. Anodising may cause the screws to bind, thus the threaded holes may need to be chased with a tap to restore the original dimensions. In the case of unthreaded holes that accept screws or pins a slightly oversized hole to allow for the dimension change may be appropriate. Screw thread, used to convert torque into the linear force in the flood gate. ... Screws come in a variety of shapes and sizes for different purposes. ... Taps and dies are generally metalworking tools for the creation (cutting) of screw threads in metal parts. ...

Plasma electrolytic oxidation is a similar process, but where higher voltages are applied. This causes sparks to occur, and results in more crystalline type coatings. Plasma electrolytic oxidation, or microarc oxidation, is an electrochemical surface treatment process for metals. ... In the physical sciences, potential difference is the difference in potential between two points in a conservative vector field. ...

External links

• Article on anodising and dyeing from Coating and Fabrications Magazine
• DIY Aluminium anodising