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2022
Book Article
Title
NDE in Additive Manufacturing of Ceramic Components
Abstract
Additive manufacturing of ceramic green bodies is a new manufacturing or more precisely a shaping technology for ceramic components. Any additive shaping technology is embedded in the established manufacturing chain of structural ceramic components. A key advantage of additive methods is the flexibility in low volume manufacturing. The quality management for these parts is of high importance and requires new approaches beyond statistical sampling.
Optical methods are perfectly suited to be used in ceramics manufacturing as they are fast, versatile, and noncontacting. However, they have to be adopted to the specifics of any process. The methods presented here are methods used within an additive manufacturing device focused on various specific shaping technologies in development.
Laser Speckle Photometry (LSP) is an optical nondestructive testing method. It is based on the dynamic analysis of time-resolved speckle patterns that are generated by an external excitation. In this chapter, we will present two investigation categories using the LSP technique for lithography-based Vat Photopolymerization (CerAM VPP): first, detection of surface defects caused by local failures by selectively fill-up during the building up of layer and second, the supervision of mixing of two components in uncured slurry (suspension) or already cured multimaterial. In a second part, the results of inline characterization of correct layering of drops during Multi Material Jetting (CerAM MMJ) are presented.
The optical coherence tomography (OCT) method utilizes a short coherence light to illuminate the investigated sample. Depending on the optical properties of the sample, especially the translucency at the wavelengths used, the light can penetrate from couple hundreds of micrometers to couple of millimeters into the sample. Presence of inclusions, pores, defects, delamination will cause a partial or total backscattering of the light. We used the OCT method to investigate ceramic structures printed in the lithography-based manufacturing process. We were able to visualize surface defects, extract quantitative geometrical information on the printed structures, as well as the surface roughness. Also, material contrast for multicomponent samples was visualized.
Optical methods are perfectly suited to be used in ceramics manufacturing as they are fast, versatile, and noncontacting. However, they have to be adopted to the specifics of any process. The methods presented here are methods used within an additive manufacturing device focused on various specific shaping technologies in development.
Laser Speckle Photometry (LSP) is an optical nondestructive testing method. It is based on the dynamic analysis of time-resolved speckle patterns that are generated by an external excitation. In this chapter, we will present two investigation categories using the LSP technique for lithography-based Vat Photopolymerization (CerAM VPP): first, detection of surface defects caused by local failures by selectively fill-up during the building up of layer and second, the supervision of mixing of two components in uncured slurry (suspension) or already cured multimaterial. In a second part, the results of inline characterization of correct layering of drops during Multi Material Jetting (CerAM MMJ) are presented.
The optical coherence tomography (OCT) method utilizes a short coherence light to illuminate the investigated sample. Depending on the optical properties of the sample, especially the translucency at the wavelengths used, the light can penetrate from couple hundreds of micrometers to couple of millimeters into the sample. Presence of inclusions, pores, defects, delamination will cause a partial or total backscattering of the light. We used the OCT method to investigate ceramic structures printed in the lithography-based manufacturing process. We were able to visualize surface defects, extract quantitative geometrical information on the printed structures, as well as the surface roughness. Also, material contrast for multicomponent samples was visualized.