Samples metallurgical

Atomic fluorescence methods have been applied to the determination of metals in such materials as lubricating oils,. seawater, geological samples, metallurgical samples, clinical. samples, environmental samples, and agricultural samples. Table 9-3 IKsls detection limits for atomic fluorescence procedures. 

The determination of silicon is commonly encountered in metallurgical and mining laboratories responsible for the analysis of ores, slags, and alloys. The volatilization gravimetric method, which is appropriate for samples containing high concentrations of silicon, was described earlier in Method 8.2. 

Increasing the driver plate velocity and driver plate thickness for a fixed sample assembly results in an increased peak shock pressure and pulse duration. As far back as the review of Appleton [32] in 1965 on metallurgical... 

Fig. 3.35. HF-plasma SNMS survey signals coming from adsorbed and respectrum of a powder metallurgically- sputtered plasma gas contamination, produced TiAl alloy sample. In brackets ...

The above data relate to very pure iron samples with low dislocation densities. In real steels the trapping effects result in much lower apparent diffusivities, which are dependent on the metallurgical state of the steel, as well as its chemical composition. Typical values for the apparent diffusion coefficient of hydrogen in high-strength alloy steel at room temperature are in the region of 10" mVs. 

In practice resistivities between 0-08 and 0-29 ohm m have been recorded on coke breeze samples used in typical groundbeds. The effect of pressure on the measured value for resistivity of different coke samples has also been reported elsewhere ". The resistivity of bulk metallurgical coke is given as 0-024 ohm m with a slightly lower value of 0-020 ohm m at a pressure of 0-43 Nm whilst in calcined fluid petroleum coke at zero applied pressure the resistivity was 0 - 02 ohm m, which decreased to 0 - 002 ohm m when tested at an applied pressure of 1-31 MNm... 

Fe, Re and Mo samples were typically of about 1 cm area by 0.5 mm thick and were spark cut from single crystal rods. These were subsequently polished using standard metallurgical techniques euid... 

Samples may either be those in which the surface of interest has been exposed to the environment before analysis, or the surface to be examined is created in the UHV chamber of the instrument. The latter method is generally preferable, and also argon-ion bombardment is commonly used to clean sample surfaces in situ in the spectrometer. In metallurgical studies, the fracture sample is particularly important the sample is machined to fit the sample holder, and a notch is cut at the desired point for fracture. The fracture stage is isolated from the analytical chamber and is pumped down to UHV. Liquid nitrogen cooling is often provided, as this encourages... 

The technique is used predominantly for the isolation of a single chemical species prior to a determination and to a lesser extent as a method of concentrating trace quantities. The most widespread application is in the determination of metals as minor and trace constituents in a variety of inorganic and organic materials, e g. the selective extraction and spectrometric determination of metals as coloured complexes in the analysis of metallurgical and geological samples as well as for petroleum products, foodstuffs, plant and animal tissue and body fluids. 

Dissolution of metallurgical or ore samples containing iron often requires the use of hydrochloric acid. Iron(II) is readily titrated with potassium permanganate = in strong acid solution. 

Extensive numbers of inorganic ions are determined with excellent precision and accuracy widely used in routine assays of metallurgical and mineralogical samples. Relative precision 0.1-1%. 

The GDL can be used for the analysis of trace, minor and major constituents in electrically conducting samples, especially metallurgical specimens. Similar detection limits to arc/spark methods are observed but with greater freedom from interferences and much improved precision (Figure 8.9). 

Atomic absorption spectrometry is one of the most widely used techniques for the determination of metals at trace levels in solution. Its popularity as compared with that of flame emission is due to its relative freedom from interferences by inter-element effects and its relative insensitivity to variations in flame temperature. Only for the routine determination of alkali and alkaline earth metals, is flame photometry usually preferred. Over sixty elements can be determined in almost any matrix by atomic absorption. Examples include heavy metals in body fluids, polluted waters, foodstuffs, soft drinks and beer, the analysis of metallurgical and geochemical samples and the determination of many metals in soils, crude oils, petroleum products and plastics. Detection limits generally lie in the range 100-0.1 ppb (Table 8.4) but these can be improved by chemical pre-concentration procedures involving solvent extraction or ion exchange. 

Non-destructive elemental analysis of solid or liquid samples for major and minor constituents. Used in routine analysis of metallurgical and mineral samples. Most suited to the determination of heavy elements in light matrices (e.g. Br or Pb in petroleum). Well suited for on-stream, routine analysis. Electron beam excitation methods valuable in surface studies in combination with electron microscopy. Detection limits generally in the range 10-100 ppm. Relative precision, 5-10%. 

Standard methods of preparing samples for metallurgical examination sometimes involve extremely hazardous combinations of oxidants, such as nitric or perchloric acid, and organic solvents. These are frequently destabilised by metal catalysis. Resultant incidents will be recorded under the entry for the oxidant in question. 

Thaulow, N. and White, E.W. (1971) General method for dispersing and disaggregating particulate samples for quantitative S EM and optical microscope studies. Technical Report 5 (US Department of Commerce Technical Report AD733457), Office of Naval Research, Metallurgical Program. 

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