Microstructure analysis and compressive performance of diamond/Al ₂ O ₃ composites by digital light processing technology

Alumina (Al2O3) ceramics with complex geometry are widely used in aerospace thermal components, cutting tools, and catalyst supports because of their excellent thermal stability, corrosion resistance, and wear resistance. However, low ductility problem existed in such brittle material and influences its long-term stable service in extreme environments, especially under load-bearing conditions. Adding carbon material were considered as an effective method to improve mechanical properties of ceramics. In this work, diamond/Al2O3 composites were fabricated using digital light processing (DLP) additive manufacturing technology. Meanwhile, their microstructure, phase composition, and compressive properties were systematically investigated here. After sintering treatment, Al2O3 particles retained a well-defined morphology and unchanged phase composition, which had an average particle size of 6 μm. Diamond particles had an average particle size of 1 μm and transformed obviously from a crystalline structure to an amorphous state, accompanied by characteristic graphitization peaks. From mechanical properties testing results of DLP composites, the specimens exhibited elastic modulus of 331.23 ± 8.69 MPa and compressive strength of 46.19 ± 1.07 MPa. Specially, diamond/Al2O3 composites specimens had an increasing in elongation (27.26 ± 0.17%) compared with pure Al2O3 specimens. This indicated carbonized diamond particles had a positive effect on enhancing the ductility of Al2O3 ceramics. These scientific finding will provided an important reference for investigating additive manufacturing high-performance ceramics.