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The processes of chemical coloring of metals are as old as metalworking technology. Some of the earliest-known examples of colored metal objects are about 5,000 years old. They are bronze casts with some silver-colored parts, which originate from the Anatolian region. [2] Similar processes can be found on some ancient Egyptian copper sheets. [3]
Titanium tetrachloride is also used to make titanium dioxide, e.g., for use in white paint. [52] It is widely used in organic chemistry as a Lewis acid, for example in the Mukaiyama aldol condensation. [53] In the van Arkel–de Boer process, titanium tetraiodide (TiI 4) is generated in the production of high purity titanium metal. [54]
Titanium alone is a strong, light metal. It is stronger than common, low-carbon steels, but 45% lighter. It is also twice as strong as weak aluminium alloys but only 60% heavier. Titanium has outstanding corrosion resistance to seawater, and thus is used in propeller shafts, rigging and other parts of boats that are exposed to seawater.
This can only be used as a very rough guide, for instance if a narrow range of wavelengths within the band 647–700 nm is absorbed, then the blue and green receptors will be fully stimulated, making cyan, and the red receptor will be partially stimulated, diluting the cyan to a greyish hue.
Flame test of a few metal ions A flame test involves introducing a sample of the element or compound to a hot, non-luminous flame and observing the color of the flame that results. [ 4 ] The compound can be made into a paste with concentrated hydrochloric acid, as metal halides , being volatile, give better results. [ 5 ]
Grey-blue – 371 °C (700 °F) and higher – structural steel; For carbon steel, beyond the grey-blue color the iron oxide loses its transparency, and the temperature can no longer be judged in this way, although other alloys like stainless steel may produce a much broader range including golds, teals, and magentas.
Bluing can also be done in a furnace, for example for a sword or other item traditionally made by a blacksmith or specialist such as a weapon-smith. Blacksmith products to this day may occasionally be found made from blued steel by traditional craftsmen in cultures and segments of society who use that technology either by necessity or choice.
The blade is made of non-rustproof carbon steel, blue-plastered by hand and finely forged from the base to the tip of the knife. The 90 mm (3.5 in) long blade shows patina (dark spots) caused by decades of use. It can easily be sharpened to a shaving sharp edge. Carbon steel is a popular choice for rough-use knives and cheaper options.