Fiber composites specimen preparation methods

Microscopy techniques can be used to evaluate the size and distribution of particles added to polymer fibers, such as metals that modify the physical, mechanical, or electrical properties. In general, ultrathin sections are examined in either STEM or TEM modes to reveal the particles within the polymer. Energy (EDS) and wavelength dispersive x-ray spectroscopy (WDS) methods are used to map for various elements in order to establish the relation between the particle morphology and chemical composition. A specimen preparation method for x-ray analysis in the SEM is to use a trimmed block face, which remains after cutting thin sections, or to study a thick section. An example of such a study is described below. 

The majority of work done on VGCF reinforced composites has been carbon/carbon (CC) composites [20-26], These composites were made by densifying VGCF preforms using chemical vapor infiltration techniques and/or pitch infiltration techniques. Preforms were typically prepared using furfuryl alcohol as the binder. Composites thus made have either uni-directional (ID) fiber reinforcement or two-directional, orthogonal (0/90) fiber reinforcement (2D). Composite specimens were heated at a temperature near 3000 °C before characterization. Effects of fiber volume fraction, composite density, and densification method on composite thermal conductivity were addressed. The results of these investigations are summarized below. 

The method of adiabatic calorimetry for specific heat measurement has been described by Collings and Smith [ ]. In the previous experiments with alloys, ground and polished surfaces achieved good thermal contact with the heater/thermometer pedestal by means of a thin layer of silicone vacuum grease. For the composites, a different specimen preparation and mounting procedure was used. Each sample was made up of five slabs (about 2.5 cm x 2.5 cm x 0.3 cm) of material cemented together, fibers parallel, with methanol-diluted GE 7031 varnish. To maximize heat transfer, one face of the laminated sample was ground... 

---