Fused deposition modeling possesses great advantages in fabricating high performance composites with controllable structural designs. As such, it has attracted attention from medical, automatic, and aerospace fields. In this paper, the influence of short carbon fibers (SCFs) and the orthogonal building orientation on the flexural properties of printed polyether ether ketone (PEEK) composites are systematically studied. The results show that the addition of SCFs raises the uniform nucleation process of PEEK during 3D printing, decreases the layer-to-layer bonding strength, and greatly changes the fracture mode. The flexural strength of vertically printed PEEK and its CF-reinforced composites show strengths that are as high as molded composites. X-ray micro-computed tomography reveals the microstructure of the printed composites and the transformation of pores during bending tests, which provides evidence for the good mechanical properties of the vertically printed composites. The effect of multi-scale factors on the mechanical properties of the composites, such as crystallization in different positions, layer-by-layer bonding, and porosity, provide a successful interpretation of their fracture modes. This work provides a promising and cost-effective method to fabricate 3D printed composites with tailored, orientation-dependent properties.

Fused filament fabrication (FFF) is one of the most widely used additive manufacturing (AM) technologies and it has great potential in fabricating prototypes with complex geometry. For high quality manufacturing, monitoring the products in real time is as important as maintaining the FFF machine in the normal state. This paper introduces an approach that is based on the vibration sensors and data-driven methods for in-situ monitoring and diagnosing the FFF process. The least squares support vector machine (LS-SVM) algorithm has been applied for identifying the normal and filament jam states of the FFF machine, besides fault diagnosis in real time. The identification accuracy for the case studies explored here using LS-SVM is greater than 90%. Furthermore, to ensure the product quality during the FFF process, the back-propagation neural network (BPNN) algorithm has been used to monitor and diagnose the quality defects, as well as the warpage and material stack caused by abnormal leakage for the products in-situ. The diagnosis accuracy for the case studies explored here using BPNN is greater than 95%. Results from the experiments show that the proposed approach can accurately recognize the machine failures and quality defects during the FFF process, thus effectively assuring the product quality.

SiBCN/Si₃N₄w components with high mechanical properties were manufactured using DLP 3D-printing technology.

The in situ resource utilization of lunar regolith is of great significance for the development of planetary materials science and space manufacturing. The material extrusion deposition approach provides an advanced method for fabricating polylactide/lunar regolith simulant (PLA/CLRS-1) components. This work aims to fabricate 3D printed PLA–lunar regolith simulant (5 and 10 wt.%) components using the material extrusion 3D printing approach, and realize their solvent dissolution recycling process. The influence of the lunar regolith simulant on the mechanical and thermal properties of the 3D printed PLA/CLRS-1 composites is systematically studied. The microstructure of 3D printed PLA/CLRS-1 parts was investigated by scanning electron microscopy (SEM) and X-ray computed tomography (XCT) analysis. The results showed that the lunar regolith simulant can be fabricated and combined with a PLA matrix utilizing a 3D printing process, only slightly influencing the mechanical performance of printed specimens. Moreover, the crystallization process of PLA is obviously accelerated by the addition of CLRS-1 because of heterogeneous nucleation. Additionally, by using gel permeation chromatography (GPC) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) characterization, it is found that the 3D printing and recycling processes have a negligible influence on the chemical structure and molecular weight of the PLA/CLRS-1 composites. As a breakthrough, we successfully utilize the lunar regolith simulant to print components with satisfactory mechanical properties and confirm the feasibility of recycling and reusing 3D printed PLA/CLRS-1 components via the solvent dissolution recycling approach.

The water-soluble salt-based ceramic cores can be recycled and have excellent high-temperature chemical stability. In this work, vat photopolymerization had been successfully applied to water-soluble salt-based ceramic cores for the first time. The powder raw materials of the printing suspension were sodium chloride and alumina. High-precision green bodies were manufactured by optimizing suspensions and parameters. In addition, the post-processing method had been optimized according to the microstructure and mechanical properties. The sintered part had high bending strength and smooth surface. Finally, the dissolution rate and moisture resistance were compared under different dissolution and storage conditions. Compared to traditional manufacturing methods, vat photopolymerization enables the production of complex structures without molds and reduces production costs. This technology is suitable for the rapid iteration of complex structural parts and can be applied to precision parts in aerospace, military, and other technical fields with high cost-effectiveness and sustainability.