An AISI Type 304 stainless steel plate 152 mm by 152 mm was cut from a sheet having a thickness of 12.7 mm. To monitor the temperature of the steel slug, three vertical holes 3.5 mm in diameter were milled into the plate along its central axis, extending 51 mm, 76 mm, and 102 mm into the plate's depth. The holes were located at distances of 51 mm, 76 mm, and 102 mm from the plate's edge as shown in Figure 1. The steel plate mass was 2340 g. A density value of 8000 kg/m3 for 304 stainless steel was taken from the literature4, along with heat capacity values as a function of temperature5, as shown in Figure 2. Before testing any specimens, the steel plate was heated to a temperature of 700 ºC during two separate runs in the furnace. The plate can be optionally fitted with two allen screws (one on each side) to enable the final sandwich specimen to be suspended from an external balance on two wires. Care must be taken to assure that the wire diameter is sufficient to support the dead load during the temperature rise experienced during an actual test run. For our purposes, 16 gauge Chromel* wire has been found to be sufficient, while 24 gauge wire resulted in two premature failures during preliminary tests, with a total load on the order of 5000 g. Optionally, the final sandwich configuration can be set in the bottom center of the (bottom loading) box furnace, as shown in Figure 3, if only temperatures and not mass are to be monitored during the test.
Figure 3− A completed sandwich specimen of the fumed-silica insulation board mounted and ready for testing in the box furnace.
*Certain commercial products are identified in this paper to specify the materials used and procedures employed. In no case does such identification imply endorsement by the National Institute of Standards and Technology, nor does it indicate that the products are necessarily the best available for the purpose.