Zinc brass acid corrosion

Incompatibilities and Reactivities Strong oxidizers (including bromine), ethylene oxide, nitrosating agents (e g., sodium nitrite), mercury, strong acids [Note Corrosive to many metals (e g., zinc, brass, aluminum, copper).] ... 

Ammonia is unsuitable as a neutralizer if copper-base alloys are used, because if used in excess it may destroy the metal faster than acid corrosion. The other neutralizers appear to produce protective films so that corrosion halts after an initial action. If scale-forming water is used, admiralty-metal tubes must be cleaned frequently, because corrosion occurs mainly beneath breaks or porous spots in the scale. The zinc in the brass is dissolved and is replaced by spongy copper. ... 

Brass water fittings give no trouble except that dezincification may occur in acid waters or waters of high chloride content, especially when hot. This dezincification has three effects. Firstly, the replacement of brass by porous copper may extend right through the wall of the fitting and permit water to seep through. Secondly, the zinc which is dissolved out of the brass may form very voluminous hard corrosion products and eventually block the waterway —this is often the case in hot soft waters. Thirdly, and often the most important, the mechanical properties of the brass may deteriorate. For instance, a dezincified screwed union will break off when an attempt is made to unscrew it and a dezincified tap or ball-valve seat is readily eroded by the water. 

Phosphine in small quantities in hydrogen containing over I per cent, of oxygen attacks copper, producing an acid liquid which has a most corrosive action on fabric. However, it does not appear under these circumstances to have any action on aluminium or zinc consequently any metal parts inside the envelope of an airship should be of aluminium. Phosphine under the above conditions attacks hemp and other textiles which have been treated with copper compounds, but it does not appear to have any action on fabrics free from copper compounds or copper or brass fastenings. 

Reactivity with Common Materials Corrosive to aluminum slowly corrosive to copper, brass, zinc, and tin Stability During Transport Stable Neutralizing Agents for Acids and Caustics Flush with water and then rinse with sodium bicarbonate or lime solution Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

With chemical corrosion we mean the decay of a material under the influence of a corrosive substance. When brass contains more than 15 % (m/m) of zinc, the zinc and copper ions dissolve in an aqueous environment at a high temperature. Subsequently the copper ions are deposited on the metal surface. Nitric acid is able to selectively dissolve iron out of certain ceramic materials. Molecules of a sol-... 

Copper alloys, such as brass, bronze, admiralty, and Muntz metals, can exhibit better corrosion resistance and better mechanical properties than pure copper. In general, high-zinc alloys should not be used with acids or alkalies owing to the possibility of dezincification. Most of the low-zinc alloys are resistant to hot dilute alkalies. 

Attack on metals can be a function of fuel components as well as of water and oxygen. Organic acids react with cadmium plating and zinc coatings. Traces of H2S and free sulfur react with silver used in older piston pumps and with copper used in bearings and brass fittings. Specification limits by copper and silver strip corrosion tests are required for fuels to forestall these reactions. 

CHEMICAL PROPERTIES nonflammable gas extremely stable to heat, even up to 2000°C reacts with water to form sulfurous acid (H2SO3) catalytically oxidized by air to sulfur trioxide (SOj) will slowly oxidize from sulfurous to sulfuric acid reacts with alkaline materials such as sodium and potassium reacts with some active metals like aluminum, brass, copper, and zinc may corrode aluminum corrosive when dissolved in water as sulfurous acid FP (NA) LFL/UFL (NA) AT (NA) HC (NA) HF (-320 kJ/mol liquid at 25°C, -296.8 kJ/mol gas at 25°C). 

Incompatibilities and Reactivities Hydroxides, amines, alkalis, copper, brass, zinc [Note Hydrochloric acid is highly corrosive to most metals.] ... 

Obscurants are another class of substances employed in warfare to generate thick black clouds to make objects opaque to visible and infrared radiation. Such substances used to block visible light include various petroleum products such as crude oil, motor oil, fog oil, exhaust of the coal, graphite, brass, dyes, titanium tetrachloride, chlorosulfonic acid, zinc chloride and phosphorous munitions containing red or white phosphorous in butyl rubber or polymer epoxy binder. Certain obscurants such as chlorosulfonic acid and titanium tetrachloride are widely corrosive... 

This is a type of corrosion in which brass dissolves as an alloy and the copper constituent redeposits from solution onto the surface of the brass as a metal in porous form. The zinc constituent may be deposited in place of an insoluble compound or carried away from the brass as a soluble salt. The corrosion can take place uniformly or be local. Uniform corrosion is more apt to take place in acid environments while local corrosion is more apt to take place in alkaline, neutral, or slightly acid environments. The addition of tin or arsenic will inhibit this form of corrosion. 

While it is possible to bond to a freshly abraded or cleaned metal surface, chemical treatments are preferred for rendering the metal surface inactive to corrosion over time. For low carbon steel, phosphatising is the recommended pre-bond surface preparation treatment. Stainless steel should be passivated or acid etched, while titanium is usually treated with a hydrofluoric acid pickle. Almninium or magnesium are best treated with a chromate conversion coating. Zinc and cadmium are generally prepared mechanically but a phosphate or chromic acid treatment may be used. Brass and copper may be treated with an ammonium persulphate etch or an acid-ferric chloride etch. 

Copper and brass should not be used in any process flow stream that will allow exposure of the metal to solutions carrying chlorine (2 ppm or more). This is especially critical in reclaimed water systems, since chlorine can cause severe corrosion of copper and brass. Brasses containing over 15 percent zinc may suffer dezincification. This form of corrosion is especially prevalent in stagnant, acidic solutions. 

A less but still complicated situation is found for actively corroding alloys which are not covered by passive layers, particularly in acidic electrolytes. In many cases, the very different corrosion characteristics of the alloying elements lead to preferential dissolution of one metal component. The preferential oxidation or dissolution of the zinc of brasses and the related accumulation of copper at the surface is a technologically important example of dealloying of a metal surface. In this case zinc is much more... 

In the case of brasses, consideration must be given to the risk of dezindfication, especially at high zinc levels. Soils contaminated with detergent solutions and ammonia also pose a higher corrosion risk for copper and copper alloys. Additional corrosion protection for copper and copper alloys is usually considered only in highly corrosive soil conditions. CP, the use of acid-neutralizing backfill such as limestone, and protective coatings can be used in these applications. 

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