by clicking the arrows at the side of the page, or by using the toolbar.
by clicking anywhere on the page.
by dragging the page around when zoomed in.
by clicking anywhere on the page when zoomed in.
web sites or send emails by clicking on hyperlinks.
Email this page to a friend
Search this issue
Index - jump to page or section
Archive - view past issues
button in toolbar for more information.
Metal Casting Technologies : March 2008
by electromagnetic condenser lenses to the order of 5nm. In scanning mode the beam can then be made to scan in a rectangular raster over selected regions of the specimen being examined. When the electrons meet the specimen a number of interactions occur from which useful information about the specimen can be obtained. The main effects are: ■ Back scattering of electrons giving a BSE image that depends on atomic number and thus enabling, smooth surface metallography with no need for etching. ■ Generation of secondary electrons giving a SE image that depends largely on surface topography enabling, for example the study of rough surfaces and deeply etched specimens. Examples of the use of BSE and SE images were given in the previous article . ■ Generation of characteristic X-rays whose energies, and hence wavelengths, depend on the elements present in the volume of the specimen being irradiated by the electron beam. Measuring the relative intensity of each characteristic X-ray energy or wavelength peak then enables the amount of its parent element to be determined. The volume of the specimen generating X-rays depends on the original energy of the incident beam, the density (atomic number) of the specimen, and the energy of the characteristic X-ray that is to be measured. The depth of penetration and the size of the interaction volume can be calculated in terms of these factors. Figure 1 shows the shape of interaction volumes for thin and bulk specimens. The position of the X-ray detector METAL Casting Technologies March 2008 41 Fig 2. The effect of take off angle on the length of the absorption path within the specimen  Beckwith Macbro Resin Coated Sands All grades of resin coated sand used for shell molding and shell cores for ferrous and non-ferrous applications PRODUCTS ■ Range of resin strengths from 1.0% to 5.0% ■ Silica, Zircon, Chromite coated sands or blended mixes ■ Coated Sands of different AFS typically from 50-90 AFS ■ Thermal Reclaimed Coated Sands SERVICES ■ Full technical and trouble shooting service. ■ On-site shell core and shell molding facility to evaluate the product applications. ■ Laboratory facility to ensure product quality. Contact : Rob Dalla Via 30 Devon Road Devon Meadows, Melbourne Telephone: +61 3 5995 4244 Mobile: 0417 332 723 Fax: +61 3 5995 5030 E-mail: email@example.com Website: www.beckwithmacbro.com.au