Si3N4粉体的表面改性及其对立体光刻成型的影响

传统的陶瓷加工技术成本高、周期长、缺陷多,难以生产高性能陶瓷,立体光刻技术是制造形状复杂陶瓷零件的一种高效手段。纯Si₃N₄粉体的折射率(n=2.1)与树脂(n=1.49)的折射率相差较大,光散射严重,导致其陶瓷浆料的固化深度较低,很难直接利用立体光刻技术成型Si₃N₄陶瓷零件。为解决Si₃N₄粉体难以光固化的难题,本研究采用表面包覆有机物和表面氧化两种方式改性Si₃N₄粉体,并对比两种方式对Si₃N₄粉体光固化特性的影响规律。结果表明,包覆实验后,有机物单体经过一定反应时间后可均匀附着在Si₃N₄粉体表面;氧化处理后,Si₃N₄粉体表面形成非晶SiO₂层,该层均匀附着在粉体表面上。原始Si₃N₄粉体的固化深度仅为20 μm,经过包覆改性和800 ℃氧化4 h后,Si₃N₄粉体的固化深度分别可提高到40 μm和50 μm,两种方式均能有效提高原始Si₃N₄粉体的固化深度。

Surface Modification of Si3N4 Powder and Its Effect on Digital Light Processing

Traditional ceramic processing technology has high cost, long cycle and many defects, which makes it difficult to produce high-performance ceramics. The refractive index (n=2.1) of pure Si₃N₄ powder is quite different from that of resin (n=1.49), and the light scattering is serious, which leads to the lower curing depth of the ceramic paste. It is difficult to directly use stereolithography technology to form Si₃N₄ ceramic parts. In order to solve the problem that Si₃N₄ powder is difficult to be cured, two methods of surface coating and surface oxidation were used to modify Si₃N₄ powder, and the influence of the two methods on the light curing characteristics of Si₃N₄ powder was compared. The results show that the organic monomer uniformly attaches to the surface of Si₃N₄ powder after a certain reaction time; after being oxidized at 800 ℃ for 4 h, amorphous SiO₂ layer is formed on the surface of Si₃N₄ powder, which is uniformly attached to the surface of Si₃N₄ powder. The curing depth of original Si₃N₄ powder is merely 20 μm, and the curing depth of Si₃N₄ powder after coating modification and oxidation modification increase to 40 μm and 50 μm, respectively. Both methods effectively improve the curing depth of original Si₃N₄ powder.