Foils, test specimens

For cellular elastomers and cellular plastics, rigid or flexible, the back and sides of the test specimen must be wrapped with aluminum foil and asbestos cement board used as backing. Other special requirements for cellular materials are also in effect. 

Following particle deposition, the test specimens should be evaluated in a temperature/humidity environmental chamber. With electronic equipment, bias should be applied to the specimen as well, and the device or equipment assembly should imdeigo a foil series of functional tests. 

A measurement of the quantity A soo is obtained from a knowledge of the actual flux distribution in the test specimen. The usual experimental procedure is to obtain a measure of the relative flux at various stations along the axis of the parallelepiped by means of metallic foils. The activation of these foils due to neutron captures is directly proportional to the flux level at the foil. Thus a plot of the foil activities as a function of position along the axis will yield a curve having the spatial form of the axial thermal flux. Moreover, if this curve is drawn on semilog paper, it will display a linear behavior in the intermediate range AS, as shown in Fig. 5.266. The slope of this curve yields the quantity fcaoo. But, from (5.243) we have that... 

Spot test analysis makes frequent use of electrochemical separation methods. Especially in paper chromatography use is made of differential diffusion in which an electrical field serves to accomplish the desired separation. Of particular interest in spot test analysis is the employment of electrographic methods for examining metals, alloys and ores. The basic principle employed is the anodic solution of the metals. In practice, the specimen is made the anode and a piece of aluminum foil serves as cathode. Filter paper is moistened with the appropriate reagent solution and then placed between these two electrodes. The proper voltage is then applied. The movement of the metals then leads to an imprint on the paper and so reveals the exact position of the metals that have migrated from the surface of the test specimen. Hermance and Wadlow have published a comprehensive review of this procedure. 

The results listed in Table VII-5 were determined on test specimens, prepared from about 3 g of very pure copper which had been reduced with hydrogen, and which contained g guantities of the oxides under investigation, placed in a borehole which was subsequently blocked up with a 1ittle platinum foil. 

For comparison, isothermal and cyclic furnace oxidation tests were carried out using the same temperatures and durations as used in the resistance heating tests. These tests were either performed isothermally in a microbalance (SETERAM) in synthetic air or in a conventional resistance heated vertical tube furnace in laboratory air. In the latter tests each cycle consisted of 300 s heating and 900 s cooling. The test specimens used in the furnace tests were coupons of 20 x 5 mm in size which were cut from the 50 pm thick foils. 

The specimens of pure iron and Fe-Ni(0.5 5.0 wt.%) alloys were made as thin foils of 20- -25 pm thickness for electron microscopy, Mossbauer spectroscopy and as plates of 0.8- 1.5 mm thickness for mechanical tests. 

When samples of unknown behavior are tested, investigators will often line the bottom of the casing (under the specimen) with alumina pellets or platinum foil. This will protect the casing against accidental specimen melting. Platinum foil can be used as an interface between pushrod/specimen and speci-men/casing back in order to protect against inadvertent reaction. The expansion of the known thickness of platinum used must then be corrected for in the specimen expansion data. 

The skin is cleaned and anesthetized as for other similar procedures, and lOmL of fluid is aspirated into a syringe connected to the spinal needle that is typically used. Sterile containers such as polypropylene test tubes or urine cups are used to transport the fluid to the laboratory. If a specimen is for the determination of the lecithin-sphingomyelin (L/S) ratio, the container is immediately placed in ice if it is for spectrophotometric analysis, the specimen should be transferred to a brown tube or bottle to prevent photodegradation of bilirubin. Alternatively the specimen container may be wrapped in aluminum foil. 

Figure 7.42 Almen test configuration to measure the specimen curvature, (a) Mounting block and (b) a thin foil before (1) and after grit blasting (2). The convex curvature will be reduced by tensile stresses induced during coating (3) (SAE Handbook, 1977).

ASTM E906 [99] defines the OSU calorimeter. The apparatus consists of an insulated box containing a vertical specimen, a parallel electric radiant heater, and a pilot ignition device. Air at a controlled rate flows through the box, and the inlet and outlet temperatures arc recorded. ASTM E906 also records the temperature of the box wall to compensate for the nonadiabatic characteristics of the apparatus. The box is calibrated using a preset gas flame. The vertical specimen size is 150 mm square, and the incident heat flux has a maximum value of 100 kW, m. Tests with a horizontal specimen, 110 x 150mm, which involve the use of aluminum foil to reflect heat onto the specimen, are apparently... 

Lead (0.003 in.) 3 Bond between foil and laminate broken in center of specimen— Lead foil O.K. Bond between foil and laminate became worse— lead O.K., but elongated Lead broken on unbonded section Testing stopped... 

Iwasaki and Todoroki [92] use a response surface technique to process the electrical resistance measurements. A large number of cross-ply and quasi-isotropic specimens were tested such that statistical data processing could be applied. Copper-foil electrodes mounted on one side of the CFRP specimens during prepreg layup were co-cured with the specimen (Figure 16.39). Impact-induced matrix cracking and delaminations were detected. Probability of location estimation and error bands were computed [92]. The extension of this method to woven CFRP composites is described in Hirano and Todoroki [93]. 

The specimen is placed between two halves of the holder that are held together by screws or clamps. The holder can move closer to or away from a 45°-propane gas burner (similar to a Bunsen burner). A 100-mm x 50-mm x 10-nun deep aluminum foil tray containing filter paper is placed beneath the specimen holder and replaced between the tests. 

---