Scanning Electron Microscopy (SEM), also known as SEM analysis or SEM microscopy, is performed with a Scanning Electron Microscope. MDT has an Aspex Model 3025 SEM system with Automated Feature Analysis (AFA) Software and Energy Dispersive X-ray Spectroscopy (EDS) capabilities. Scanning electron microscopy is performed at high magnifications, generates high-resolution images and precisely measures very small features and objects.
SEM microscopy is used very effectively in microanalysis and failure analysis of solid materials. The signals generated during analysis produce a two-dimensional image and reveal information about the sample including external morphology (texture), chemical composition (when used with EDS) and orientation of materials making up the sample.
The EDS component of the system is applied in conjunction with SEM analysis to determine elements in or on the material surface or on particles shed by the sample for qualitative information or to measure elemental composition. Foreign substances that are not organic in nature and coatings on metal can also be identified through EDS.
The SEM microscopy equipment includes a variable pressure system capable of holding wet and/or non-conductive samples with minimal preparation. The large sample chamber allows for the examination of samples up to 100 long x 80mm wide x 25mm high. High-resolution images are produced during SEM analysis at magnifications to 100,000x. The EDS features a silicon drift detector (SDD) that offers superior speed and energy resolution compared with traditional SiLi detectors. The system is powered by the AFA software package that facilitates material characterization via methods such as spectral analysis, line scans, and element mapping. The software also features particle size characterization and analysis.
Scanning Electron Microscopy uses a focused beam of high-energy electrons to generate a variety of signals at the surface of solid specimens. In most SEM microscopy applications, data is collected over a selected area of the sample surface and a two-dimensional image is generated that displays spatial variations in properties including chemical characterization, texture and orientation of materials. The SEM is also capable of performing analyses of selected point locations on the sample. This approach is especially useful in qualitatively or semi-quantitatively determining chemical compositions, crystalline structure and crystal orientations. The EDS detector separates the characteristic X-rays of different elements into an energy spectrum, and EDS system software is used to analyze the energy spectrum in order to determine the abundance of specific elements. A typical EDS spectrum is portrayed as a plot of X-ray counts vs. energy (in keV). Energy peaks correspond to the various elements in the sample. EDS can be used to find the chemical composition of materials down to a spot size of a few microns and to create element composition maps over a much broader raster area. Together, these capabilities provide fundamental compositional information for a wide variety of materials, including polymers and metals.