Enhanced crack resistance in ceramic shells fabricated with photosensitive resin models printed by stereolithography through buffer layer integration.

Stereolithography (SLA) shows great market potentials in preparing ceramic shells for precision casting due to its capability of rapid producing complex molds with smooth surface and accurate dimension. However, the cracks of ceramic shell derived from the distinct thermal expansion coefficients of the SLA photosensitive resin and the ceramic shell hinders its wide application in the industry. In this work, a buffer layer integration (BLI) is demonstrated as an effective countermeasure. A film of carnauba wax with a thickness of ∼100 μm is manipulated uniformly coated on the surface of SLA photosensitive resin prototype, which is designed to release the thermal stress during the dewaxing and sintering process. After sintering, the BLI-ceramic shell shows no obvious cracks on the surface in comparison with that of regular ones, and the surface quality of the face-coat remains the same, demonstrating the enhancement of crack resistance. The finite element simulation shows the results in agree with the experiments, which suggests that the carnauba BLI can supply sufficient buffering space when its thickness is over 100 μm and keeps intimate contact with the matrix. The casting process was performed onto the BLI-ceramic shells, and the castings (30 mm) with high precision (CT 8) and good surface (Ra 1.975) were obtained. This facile and straightforward BLI process is believed promising industrially. [ABSTRACT FROM AUTHOR]