Vat photopolymerization (VPP) encounters difficulties in fabricating high-strength, low-shrinkage ceramic cores with high-precision and high quality using high-solid-loading, high-viscosity slurries. This study developed a high-solid-loading (71 vol%) silica-based ceramic slurry using spherical powders. Notably, spherical particle slurry presents favorable Newtonian fluid behavior, effectively inhibiting interlayer stair-stepping effect and large pore formation. The proposed uniform temperature field-assisted vat photopolymerization (TF-VPP) method reduced the slurry viscosity from 103.4 Pa·s at 25°C to 8.6 Pa·s (100s^-1) at 55°C. It simultaneously achieved uniform stair-stepping effects in the TPMS structure and high-precision fabrication of fine micropore features (minimum size: 50 μm). The temperature field mitigated residual stresses in ceramic green bodies, enhanced interlayer bonding and apparent Young's modulus. Compared with air debinding, the vacuum debinding and sintering process suppresses the formation of the ZrSiO₄ phase while promoting densification. The average porosity and Z-axis shrinkage were approximately 20.03% and 4.43%, respectively. The average room-temperature (25°C) and high-temperature (1550°C) flexural strength reached 12.43 MPa and 22.56 MPa, respectively, representing substantial improvements of 36.4% and 61.6%. According to CT pore characterization, core samples fabricated via vacuum debinding primarily feature small pores, without noticeable cracks. With 71vol% spherical powder slurry, the proposed TF-VPP coupled with vacuum debinding fabricates large-size (108.71mm) silica-based ceramic cores featuring low shrinkage and superior comprehensive properties. Moreover, this integrated approach offers a systematic framework for the high-precision printing of ultra-high-solid-loading ceramic slurries and for defect-free ceramic sintering.

Manufacturing micro-holes in non-conductive ceramics presents significant challenges in precision machining, particularly due to the absence of central abrasive grains in micro-grinding wheels. This study investigates helical grinding under conditions where the central abrasive grain is absent, focusing on the formation of undeformed chips. It was observed that nearly all micro-grinding wheels, regardless of their manufacturing process or grain size, exhibit a central grain absence, with larger grain sizes leading to more extensive absence areas. Analysis revealed that residual patterns at the bottom of machined holes depend on the ratio of the absence zone diameter to the wheel’s eccentricity. Analytical models were developed to describe the heights of cylindrical and disc-shaped residues, which were subsequently validated through kinematic simulations. The removal mechanisms for these residues differ; cylindrical residues, which cannot be removed by grinding, cause interference and should be avoided, while disc-shaped residues removal depends on the protrusion height of the first grain, influencing contact with the wheel’s end face and subsequent grinding actions. Experimental validation using SiC_p/Al demonstrated that cylindrical residues create distinct ring-shaped wear marks, significantly increasing cutting forces, whereas disc-shaped residues result in hat-shaped wear marks and higher cutting forces when the first grain’s protrusion is insufficient. Additionally, inadequate lubrication and chip removal can lead to chip adhesion starting from the absence zone. These findings enhance the theoretical framework of helical grinding/milling and provide valuable insights for precision machining of micro-holes in non-conductive ceramics.

Rotary ultrasonic drilling (RUD) has become an effective approach for machining advanced composites which are widely using in the field of aeronautics. The cutting kinematics and the corresponding material removal mechanisms are distinct in different drilling areas during RUD. However, these fundamentals have not been fully considered in the existing studies. In this research, two distinct forms of interaction induced by ultrasonic vibration were considered as impact-separation and vibratory lapping between the abrasives and workpiece. And the conditions to guarantee the effectiveness of these interactions were obtained to eliminate diminishing effects of ultrasonic vibration. Based on indentation fracture theory, the penetration depth of abrasives and the axial drilling force model was derived for RUD. The verification tests of C/SiC composites resulted in a prediction error within 15%. Due to the minimal volume of material removed during each vibration cycle, the drilling force was more stable in vibration assisted mode. The specific drilling energy of RUD was firstly calculated based on the measured drilling load. It was found the drilling parameters should be matched with vibration frequency and amplitude to make better usage of the advantages of ultrasonic vibration, which is critical in the vibration assisted processing of advanced materials.