氧化时间对增材制造碳化硅性能提升的作用机制

Mechanism analysis of oxidation time on performance improvement of additive manufacturing silicon carbide

增材制造结合反应烧结技术能够制备高度轻量化的碳化硅陶瓷反射镜,针对增材制造技术制备的碳化硅陶瓷存在抗弯强度低、弹性模量低等力学性能差的问题,开展高温氧化提升材料力学性能的研究。对基于增材制造的反应烧结碳化硅陶瓷试样在850℃下进行高温氧化处理,研究氧化时间对材料成分及表面缺陷含量的影响,阐明氧化时间对材料性能的提升机制,揭示它对材料性能的影响规律。实验结果表明:当氧化时间为2 h时,材料表面原位生长一层致密的氧化硅膜层,该膜层能够使材料表面缺陷自愈合,有效降低陶瓷材料表面缺陷的含量,此时材料获得最佳的力学性能,抗弯强度和弹性模量分别为263.9 MPa和384.75 GPa,分别提升10.7%和14.4%。该方法具有高效率、低成本和易操作的优势,为增材制造碳化硅陶瓷的性能优化提供理论指导。

Additive manufacturing combined with reactive sintering can be used to fabricate extremely lightweight silicon carbide ceramic mirrors.However,the mechanical properties of silicon carbide prepared by this method,such as flexural strength and elastic modulus,are low and insufficient.A novel method was proposed to improve the properties of silicon carbide by high temperature oxidation.First,sili-con carbide prepared by additive manufacturing and reactive sintering was oxidized at 850℃.Thereafter,the effect of oxidation time on material composition and surface defect content was studied.The enhance-ment mechanism of oxidation time on the properties of silicon carbide was elucidated.The results demon-strate that when the oxidation time is 2 h,a dense silica film is in-situ grown on the surface of the material,which can render the surface defects of the material to self-heal and effectively reduce their contents.In ad-dition,the final body obtained the best comprehensive properties by this method,and the flexural strength and elastic modulus are 263.9 MPa and 384.75 GPa,with increments of 10.7%and 14.4%,respective-ly.This method has the advantages of high efficiency,low cost,and easy operation.The study provides theoretical guidance for improving the performance of additive manufacturing silicon carbide ceramics.