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Hot baths of sodium hydroxide (NaOH), nitrates such as sodium nitrate (Na N O 3), and/or nitrites such as sodium nitrite (NaNO 2) [3] at 141 °C (286 °F) are used to convert the surface of the material into magnetite (Fe 3 O 4). Water must be periodically added to the bath, with proper controls to prevent a steam explosion.
Sodium nitrate is the chemical compound with the formula Na N O 3. This alkali metal nitrate salt is also known as Chile saltpeter (large deposits of which were historically mined in Chile) [4] [5] to distinguish it from ordinary saltpeter, potassium nitrate. The mineral form is also known as nitratine, nitratite or soda niter.
Chemical coloring of metals is the process of changing the color of metal surfaces with different chemical solutions. The chemical coloring of metals can be split into three types: electroplating – coating the metal surface with another metal using electrolysis. patination – chemically reacting the metal surface to form a colored oxide or ...
In the nitre bluing process, polished and cleaned steel parts are immersed in a bath of molten salts—typically potassium nitrate and sodium nitrate (sometimes with 9.4 grams (0.33 oz) of manganese dioxide per pound of total nitrate). The mixture is heated to 310 to 321 °C (590 to 610 °F) and the parts are suspended in this solution with wire.
Nanotechnology is being applied to paints to obtained the coatings having self healing capabilities and corrosion protection under insulation. Since these coatings are hydrophobic and repels water from the metal pipe and can also protect metal from salt water attack. [22] Nanoparticle based systems can provide better adhesion and transparency.
Inlet-outlet cover of a valve for a nuclear power station produced using investment casting. Investment casting is an industrial process based on lost-wax casting, one of the oldest known metal-forming techniques. [1] The term "lost-wax casting" can also refer to modern investment casting processes.
Electroless nickel-boron plating developed as a variant of the similar nickel-phosphorus process, discovered accidentally by Charles Adolphe Wurtz in 1844. [2]In 1969, Harold Edward Bellis from DuPont filed a patent for a general class of electroless plating processes using sodium borohydride, dimethylamine borane, or sodium hypophosphite, in the presence of thallium salts, thus producing a ...
For example, a 40:7:53 mixture of NaNO 2: NaNO 3:KNO 3 melts at 142 °C and is stable to about 600 °C. [4] A minor use is for coloring the light emitted by fireworks: [5] lithium nitrate produces a red color, sodium nitrate produces a yellow/orange color, potassium nitrate and rubidium nitrate produce violet colors, caesium nitrate produces an ...