Non-destructive techniques

Ultrasonic Tomographic Non-Destructive Techniques for Materials Characterization. 

There are numerous techniques which provide information related to the surface energy of solids. A large array of high-vacuum, destructive and non-destructive techniques is available, and most of them yield information on the atomic and chemical composition of the surface and layers just beneath it. These are reviewed elsewhere [83,84] and are beyond the scope of the present chapter. From the standpoint of their effect on wettability and adhesion, the property of greatest importance appears to be the Lifshitz-van der Waals ( dispersion) surface energy, ys. This may be measured by the simple but elegant technique of... 

Thermal effects, including the dehydrohalogenation of polymers such as polyvinylchloride (PVC) can also occur. However, these effects are the exception and for the most part, XPS can be considered a non-destructive technique for surface characterization. 

Sweepolet is a contoured, integral r r, rr butt-weld branch connection with a low intensification factor for low stresses -fatigue life. The attachment weld is easily amined by radiography, ultrasound and other standard non-destructive techniques. 

The electrochemical potentiokinetic reactivation (EPR) test was proposed by Cihal etal. and developed by Novak and others as a fast, quantitative and non-destructive technique for establishing the degree of sensitisation of austenitic stainless steels. 

PIGE is a rapid, non-destructive technique that is employed in the analysis of light elements such as lithium (10-100 ppm limit of detection), boron (500-1000 ppm limit of detection), and fluorine (1-10 ppm limit of detection), which are often difficult to determine by other analytical means. Because the technique is based upon specific nuclear reactions, the sensitivity of PIGE varies greatly from isotope to isotope, and this non-uniformity of sensitivity has limited its widespread use as a complementary technique to micro-PIXE. 

These difficult experimental controversies show that there is a significant role for NMR, a non-perturbing non-destructive technique that provides structural information about the local atomic environment over several bonds. 

Remote sensing applications comprising a battery of non-destructive techniques for the location and characterization of buried features at the regional, microregional and intrasite levels. 

It was not until the application of neutron activation analysis (NAA) that the problem of overlapping sources could be tackled. NAA is a highly sensitive and essentially non-destructive technique, although samples have to be taken which remain radioactive for some time after analysis. The use of NAA in characterizing obsidian was first demonstrated in the early 1970s (Aspinall... 

X-ray fluorescence spectrometry was the first non-destructive technique for analysing surfaces and produced some remarkable results. The Water Research Association, UK, has been investigating the application of X-ray fluorescence spectroscopy to solid samples. Some advantages of nondestructive methods are no risk of loss of elements during sample handling operations, the absence of contamination from reagents, etc. and the avoidance of capital outlay on expensive instruments and highly trained staff. 

This non-destructive technique is a very suitable tool for rapid in-line analysis of inorganic additives in food products (Price and Major, 1990 Anon, 1995). It can be readily used by non-skilled operators, and dry materials can be pressed into a pellet or simply poured into a sample cup. The principles of this technique related to food analysis are described by Pomeranz and Meloan (1994). A useful Internet site is http //www.xraysite.com, which includes information about different XRF instruments from various companies. Wavelength dispersive X-ray fluorescence (WD-XRF) or bench-top energy dispersive (ED-XRF) instruments are available. XRF is a comparative technique, thus a calibration curve needs to be established using food products of the same type as those to be... 

Raman spectroscopy is a non-destructive technique that is used in cosmochemistry for identification of minerals and to evaluate the bonding and composition of organic molecules. The technique does not require special sample preparation raw rock samples, polished sections, fine-grained powders, and liquids can be analyzed. Raman spectroscopy is the basis for several instruments that are under consideration for upcoming NASA missions. 

Khrushchev (1957) considers that the need to measure the force T has not been sufficiently well substantiated, nor has a sufficiently precise and easy in service hardness tester been developed yet for determinations of this type. However, he appreciates the usefulness of scratch hardness tests, especially at low loads, as a non-destructive technique. He recommends these methods as very useful for hardness determination of metallic layers or of materials exposed to abrasive wear under operating conditions (plastics, organic coatings, such as varnishes and paints, etc.). Scratch methods are especially important in tests of anisotropic materials where a change in scratch width is the measure of anisotropy. In static indentation methods, the indentations obtained in anisotropic materials are misformed, varying... 

The technique of EPR spectroscopy has proved to be a non-destructive technique with the potential for the quick and easy identification of a number of irradiated products. However considerable research is still required into products such as Crustacea, exotic fruits and various spices. There would also appear to be considerable potential in the identification of irradiation in a number of packaging materials providing additional identification which would reinforce the results of other techniques. This should help to reassure the consumer and ensure that the technique of food irradiation is not abused. 

Yantarasri, T., Kalayanamitra, K., Saranwong, S., and Somsrivichai, J. 2000. Evaluation of the maturity index for durian fruit by various destructive and non-destructive techniques. Quality assurance in agricultural produce. In ACIAR Proceedings (G.I. Johnson, Fe Van To, Nguyen Duy Due, and M.C. Webb, eds), pp. 700-705. 

---