PSI - Issue 25

A. Brotzu et al. / Procedia Structural Integrity 25 (2020) 79–87 / Structural Integrity Procedia 00 (2019) 000–000

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To eliminate processing residues and improve the surface finish, the blade was polished with a cloth soaked in acetone with the aim of reducing surface roughness without damaging the surface of the part. The prototype of the blade, made of ABS, is shown in figure 3. This has been used as a "model" for the creation of the mold used to manufacture the TiAl alloy component.

Figure 3. Prototype of the printed ABS blade. Additional prototypes of turbine blades having smaller dimensions have also been produced starting from an Inconel 718 (nickel-chromium based austenitic superalloy) blade (figure 4).

Figure 4. Inconel 718 blade. By using the ABS blade prototype, made by 3D printing, and the Inconel blade, silicone rubber molds (negative volume model) were prepared to produce the wax model. The wax models of the blades obtained are shown in figure 5.

20mm

Figure 5. Wax models of two different blades.

A refractory material resistant to high temperatures, in particular to thermal shocks, and permeable to gases evolved by the molten metal was used to produce the molds. After drying, the molds were subjected to heating to eliminate the residual moisture and melt the wax.