Non-oxidising atmosphere

Most sulfur compounds present in hydrocarbons are converted into hydrogen sulfide in a non-oxidising atmosphere at temperatures between 300 and 400 °C [ 110]. 

When a completely non-oxidising atmosphere is used (i.e., vacuum pyrolysis), it is also possible to recover carbon black from the tyre rubber. This is called pyrolytic carbon black (PCB) and it has the potential to be used in new rubber products (Section 8.2.3). 

Wolters D. Testing refractories in reducing and non oxidising atmospheres. Ind Cer-amique 1982 (766) 804-808. 

Iron-nickel alloys tend to be of lower corrosion resistance than iron-chromium alloys except towards attack by hot concentrated alkalis. Iron-chromium-nickel alloys are superior to either of the above and are resistant to alkaline and neutral aqueous solutions, atmospheric and seawater attack. Hot non-oxidising acids will cause corrosion, the rate depending on concentration and temperature. 

Moisture, plasticiser, residual solvent or other low-boiling (at 200°C or less) components Medium volatility materials degradable from 200 to 750 C (oil and polymer residues) Oxidisable material at 750 C (not volatile in unoxidised form) carbon Non-volatile residues in an oxidising atmosphere (metal components, fillers, inert reinforcing... 

In the analysis of polymers, temperatures from ambient to 1000°C can be used in either oxidising (e.g. oxygen or air) or non-oxidising (e.g. nitrogen or hehum) atmospheres, and either isothermal or dynamic heating rates can be employed. 

Structural issues related to the interconnect depend on the choice of the material. High-temperature SOFCs, such as the tubular design of Siemens-Westinghouse [111], make an exclusive use of ceramic materials, apart from the nickel felt used for current collection. The most common material, lanthanum chromite, is brittle and prone to non-uniform isothermal expansion when simultaneously subjected to reducing and oxidising atmospheres on different faces [131]. 

Like all other non-oxide ceramics Si3N4 is metastable in air or combustion gases, both at room and at elevated temperatures. Detailed understanding of oxidation and corrosion mechanisms and the influence of the surrounding atmosphere on the lifetime are necessary before Si3N4 ceramics can be applied under oxidising or corrosive conditions [431-437]. 

In the atmosphere DMS is oxidised mainly in the gas phase. Oxidation in cloud-water droplets is insignificant as the low solubility of DMS mitigates the effects of its rapid aqueous oxidation by ozone ( , McElroy, W.J., Central Electricity Research Laboratories, personal communication). Gas-phase oxidation is initiated principally by reaction with OH radicals ( ) and methanesulphonic acid (MSA) is one of the products (2). MSA has a very low vapour pressure and will be rapidly scavenged by aqueous aerosols and cloud droplets wherein further oxidation to sulphate by OH may occur. Although the kinetics and mechanism of this process have yet to be unambiguously determined, it is possible that emissions of DMS could be both a significant source of "background" sulphur and, upon oxidation, of non sea-salt sulphate. 

In 1858 Schonbem noticed that when many substances were exposed to atmospheric oxidation, the oxidisable material appeared to combine with half a molecule of oxygen, leaving the other half in the form of hydrogen peroxide or ozone. This is well exemplified by the corrosion of many non-ferrous metals, such as lead and zinc. When lead, mixed with mercury, is shaken with dilute sulphuric acid in the presence of air or oxygen, lead sulphate is formed, together with some hydrogen peroxide. The amount of the latter is readily ascertained by titration of a portion of the liquid with permanganate, and the quantity of sulphuric acid involved is estimated by titration with alkali. It is then found that the amount of peroxide formed is equivalent to that of the lead dissolved. Thus... 

At present, when working with high-purity materials, smooth solid surfaces and low P02 atmospheres, the thermodynamic contact angle in a particular system can be determined at best within about five degrees. Roughness must be very low, particularly in non-wetting systems in order to obtain such an accuracy. The control of P02 is critical for oxidisable liquids and solids, specially at relatively low temperatures, and dynamic vacuum is often preferable to a static neutral gas atmosphere. 

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