Carbon deposit particulate development

The importance of structural disorder in the metal is considered and the behaviour of well annealed material is compared to structurally less stable but clean metal surfaces. The processes that occur in the development of particulate deposits have been followed. Auger analysis of individual morphologies has highlighted particular problems in the analysis of carbon deposits after ion etching. 

Figure 13. Typical particulate deposits. Key a, larger crystalline particles, and agglomerations of smaller particles after 10,120 ton h methane b, development of stable crystal habit and c, particulate material breaking through laminar carbon...

The Development of Mound Growths. The mound carbon encapsulates the metal and prevents it from taking part in the reaction until particulate growth has caused substantial break-up of the bulk metal. Similar types of deposit have been reported in the Ni/C2H2 reaction at 990°C and Fe/CIfy system at 1100°C(19). A reduction in reactivity caused by encapsulation was reported for the Fe/CjHg deposition reaction(20)... 

For degradation forms to develop, however, it is necessary for reactions to occur that can alter or cause stress in the stone. Delivery of potential reactants to a limestone surface can be by two pathways, wet or dry. Wet deposition occurs when gaseous and particulate pollutants are incorporated into water droplets, falling as rain. This solution is usually acidic natural rainfall having a about pH of about 5.6 due to weak carbonic acid urban rainfall falls as... 

This method was developed by Stefan Huber (Karlsruhe, Germany) and consists of three size exclusion chromatography columns which divide the organic carbon into several fractions as a function of size, but also hydrophobic and ionogenic characteristics. A sample of up to 3 mL is injected into the instrument and filtered in-line with a 0.45 )um filter. The deposit on the filter is backwashed after 5 minutes and directly analysed with the TOC analyser to determine the particulate organic carbon content (POC). 

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