Ammonia environment

Corrosion also occurs as a result of the conjoint action of physical processes and chemical or electrochemical reactions (1 3). The specific manifestation of corrosion is deterrnined by the physical processes involved. Environmentally induced cracking (EIC) is the failure of a metal in a corrosive environment and under a mechanical stress. The observed cracking and subsequent failure would not occur from either the mechanical stress or the corrosive environment alone. Specific chemical agents cause particular metals to undergo EIC, and mechanical failure occurs below the normal strength (5aeld stress) of the metal. Examples are the failure of brasses in ammonia environments and stainless steels in chloride or caustic environments. 

Virtuallv evety alloy system has its specific environment conditions which will prodiice stress-corrosion cracking, and the time of exposure required to produce failure will vary from minutes to years. Typical examples include cracking of cold-formed brass in ammonia environments, cracking of austenitic stainless steels in the presence of chlorides, cracking of Monel in hydrofluosihcic acid, and caustic embrittlement cracking of steel in caustic solutions. 

Leitner NKV (1998) Chlorination and formation of organoiodinated compounds the important role of ammonia. Environ Sci Technol 32 1680-1685. 

Shaw, J.R., C.M. Wood, W.J. Birge, and C. Hogstrand. 1998. Toxicity of silver to the marine teleost (Oligocottus maculosus) effects of salinity and ammonia. Environ. Toxicol. Chem. 17 594-600. 

Pankow JF, Mader BT, Isabelle LM, Luo W, PavUck A, Liang C (1997) Conversion of nicotine in tobacco smoke to its volatile and available unprotonated form through the action of gaseous ammonia. Environ Sci Technol 31 2428-2433... 

As in isolated phenol and in phenol-ammonia/water clusters, the OH bond is broken homolytically in 7HQ-A3, resulting in the transfer of a hydrogen atom rather than proton transfer. As found for phenol-A /W and naphthol-A /W clusters, ammonia is a better hydrogen acceptor than water. Excited-state hydrogen transfer processes are thus strongly favoured in an ammonia environment. 

Michaels, R.A. (1999). Emergency planning and the acute toxic potency of inhaled ammonia. Environ. Health Perspectives, 107, pp. 617-627. 

Those alloy/environment systems that form relatively thick corrosion-product layers (e g., brass in ammonia environments) frequently exhibit preferential penetration of the corrosion products along grain boundaries. These are generally brittle products such that cracking will occur on reaching a critical depth in the presence of tensile stresses across the grain boundary. The environment again has access to the... 

E.N. Pugh, J.V. Craig, and W. Montaguer, Factors Influencing the Path of Stress-Corrosion Cracking in Alpha-Phase Copper Alloys Exposed to Aqueous Ammonia Environments, Trans. ASM, Vol 61, 1968, p 468-473... 

Suh HH, Spengler JD, Koutrakis P. 1992. Personal exposures to acid aerosols and ammonia. Environ Sci Technol 26(12) 2507-2517. 

These are the first well formed examples homoleptic ammine complexes of f-element cations, but they are extremely unstable outside of the ammonia environment, and further chemistry is difficult. 

R.C. Newman, W. Zheng, R.P.M. Procter, Stress-corrosion cracking of carbon-manganese steeb in methanol-ammonia environments—II. Electrochemical and fractographic studies, Corros. Sci. 

Chen, J. L., Shi, H. C. Xu, L. L. 2008. Effect of pH for the electrochemical oxidation products and oxidation pathways of ammonia. Environment Science 29(8) 2277-2281. (Chinese with English abstract)... 

An ammonia-rich gas stream was once accidentally charged to a gas plant. Shortly thereafter, leaks appeared in many of the tubes of the distillation towers reflux condensers. The admiralty tubes (a copper alloy in the condensers) were cracked by the ammonia environment. Admiralty may also experience stress-corrosion cracking when exposed to concentrated amines. 

In this article we present further observations on the pyrolytic phenomena of polysilazanes. Special emphasis is given to the relationship between the polymer substituents and the ceramics products and to the development of pyrolyzed compositions in an ammonia environment. 

An ammonia environment can induce SCC in copper-containing alloys, whereas with low-alloy austenitic stainless steels a chloride-containing environment is necessary. It is not necessary to have a high concentration of corrodent to cause SCC. A solution containing only a few parts per million of the critical ion is all that is necessary. Temperature and pH are also factors. There is usually a threshold temperature below which SCC will not take place and a maximum or minimum pH value before cracking will start. 

The good resistance of aluminium to nitrate and ammonia environments makes it useful in production plants, namely for buildings, as internal cladding of granulation towers, etc. [2]. 

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