## 3 Quality Control of Silicon Carbide Printed Part Formation
### The Impact and Control of Key Printing Parameters on Green Part Formation Quality
#### 3.1.3 Elimination of the Stair-Step Effect  
The step-like surface defects formed on green bodies due to the layer-by-layer deposition characteristics of binder jetting 3D printing are defined as the \"stair-step effect\" (as shown in Figure 13). The \"stair-step effect\" is considered an unavoidable systematic error in powder binder 3D printing. Theoretically, if the layer thickness in slicing approaches the infinitesimal, the edge profile of the model in the slicing software will coincide with the edge profile of the actual printed object, thereby completely eliminating the stair-step effect. However, it is important to note that the layer thickness should not be less than the maximum particle size of the powder [34] to meet the basic requirements for powder spreading and printing resolution. Figure 14 vividly illustrates the impact of the stair-step effect on the surface accuracy of thin-layer slicing versus thick-layer slicing. In actual printing, appropriately reducing powder layer thickness is a common practice to suppress the \"stair-step effect\". As summarized by [PERSON] [118], the selection of layer thickness is one of the main factors affecting the surface roughness of powder binder 3D printing technology, and the stair-step effect exhibits a proportional relationship with powder layer thickness. However, on the other hand, reducing the slicing layer thickness results in an increase in the corresponding printing time, which significantly decreases printing efficiency. Although using multiple printheads can help reduce printing time, this solution may be prohibitively expensive [119]. Figure 13: The “stair-step effect” effect in a binder jetting 3D-printed part [117]. The adaptive slicing process is proposed based on this issue, by establishing a relationship between stair-step error and model parameters to determine the thickness of layering based on the magnitude of the stair-step error for thin or thick layers at specific locations. Thin layers are applied in areas where stair-step errors are more likely to occur to ensure printing accuracy, while thicker layers are implemented in areas less likely to cause stair-step errors to increase printing speed. After [PERSON] et al. [121] developed an algorithm to address the stair-step effect by controlling the height of peaks within the tolerance range of the surface, and [PERSON] et al. [122] developed an algorithm using surface parameters to determine variable thickness, the literature on adaptive slicing technology has attracted the interest of many scholars and has begun to be widely researched. For example, the adaptive algorithm developed by [PERSON] et al. [123] is more suitable for parts with curved surfaces. Their algorithm directly applies to Non-Uniform Rational B-Spline (NURBS) surface models, allowing them to achieve precise and smooth part surfaces while employing a selectively hatched strategy to reduce build time. For instance, [PERSON] et al. [124] define the degree of the stair-step effect using the angle \(\mathrm{A_{stair}}\) between the build direction of the outer surface of the CAD (Computer Aided Design) model of the printed layer and the slicing plane. As the \(\mathrm{A_{stair}}\) angle increases, the error area significantly increases. By controlling the layer height and the \(\mathrm{A_{stair}}\) angle, the printed part's boundary can be precisely matched with that of the CAD model, which reduces the differences between the printed pattern and the CAD model, thereby minimizing the impact of the stair-step effect; thus, [PERSON]'s algorithm is more versatile. For example, [PERSON] et al. [125] utilized the OpenGL graphics library (OpenGL 1.3) to visualize solid models. This approach allows users to specify the permissible cusp height based on different tolerance requirements, thereby enabling adaptive slicing and improving the surface finish of printed parts. Their algorithm allows the slicing process to be independent of specific CAD modeling software.