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Experiments


The following sub-sections describe the preparation of the test specimens, the design of the experimental setup, and the experimental procedures. Then, a brief validation of the present tests is presented in which the elastic modulus of ASTM 304 stainless steel is measured at room and elevated temperatures. Finally, an error analysis is presented.


Specimen Preparation


The test specimens were prepared from silica lake sand, with a grain fineness number of 55 (IC55), and a phenolic ure- thane no-bake (PUNB) binder system with black iron oxide (BIO). All sand and binder system characteristics are sum- marized in Table 1. As shown in Figure 2, a nine screen test was run to obtain the grain fineness number and measure the size distribution of the sand grains. The values for the binder percentage (1.25% of total weight), binder ratio (60:40), cat- alyst percentage (8% of binder weight) and additives (BIO, 3% of total weight) were obtained by polling seven steel foundries and taking the average of their responses. The


porosity of each specimen was measured using a standard immersion test. The mean porosity of all specimens was 32.8%. Note from Table 1 that the measured porosities fall within a narrow band of ±0.9%.


The specimens were prepared by first mixing the black iron oxide into the sand using a kitchen-aid mixer to ensure a uni- form distribution. Then, the binder was added according to a procedure recommended by the binder manufacturer. Part 1 and the catalyst were added to the sand, mixed for 45 sec- onds, and then tossed to bring the sand from the bottom to the top. The batch was mixed for another 45 seconds and tossed again. After the second toss, part 2 was added to the batch and mixed for another 45 seconds, which was followed by a third and final toss. The batch was mixed for a final 45 seconds be- fore depositing it into the dump box. The sand-binder mixture was then rammed by hand into the pattern, while striving to achieve a uniform density, and allowed to set in the pattern before stripping. The specimens were stripped when the com- pacted sand withstood 20 psi of compressive stress without visible deformation.9


The dump box was capable of making six specimens with a 25.4 mm (1 in) square cross-section and Table 1. Characteristics of the PUNB Bonded Sand Specimens Used in the Elastic Modulus Measurements


Figure 2. Nine screen sieve test performed on a 50 gram sample of IC55 silica lake sand.


International Journal of Metalcasting/Fall 10


Figure 3. Photograph of a three-point bend specimen containing 1.25% binder by total weight at a 60:40 ratio of part 1 to part 2, and 3% black iron oxide.


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