低黏结剂含量SiC素坯的选区激光烧结

Al/SiC是SiC基复合材料, 具有优异的力学性能和热学性能, 在大功率电子器件、5G基站关键冷却组件、电动汽车、高速刹车片、空间探测器操作装置等相关领域具有不可替代的作用。传统制备工艺的局限性使得近净成形的无压浸渗法成为制备Al/SiC复合材料的一种较好的方法。得到高质量的碳化硅(SiC)陶瓷素坯是熔渗技术的先决条件, 选区激光烧结技术是获得高质量陶瓷素坯的一种新方法。该方法具有快速、高效的优点, 无需模具即可成型制备大规模、复杂形状部件。本研究以热塑性酚醛树脂为黏结剂, 利用机械混合与喷雾造粒的方法制备了复合粉体, 采用选区激光烧结技术制备SiC素坯, 制备了黏结剂体积分数低至15%的样品, 并对其力学性能和微观结构进行表征。当树脂含量增大到体积分数25%时, SiC坯体的强度增量为702.1%。对于喷雾造粒粉体制备的样品而言, 喷雾干粉的多孔结构使得SiC生坯的孔隙率较高(71.18%), 导致生坯强度下降。

Selective Laser Sintering of SiC Green Body with Low Binder Content

Belonging to the family of SiC-based composites, Al/SiC has excellent mechanical and thermal properties, making it irreplaceable in high-power electronic devices, key cooling components of 5G base station, electric vehicles, high-speed brake pads, space probe operation devices, and other related fields featured by high technologies. The melt infiltration method, which can achieve near-net forming, has been recognized to be a favorable method for preparing Al/SiC composites to overcome the disadvantages of traditional processing. How to obtain a high-quality silicon carbide (SiC) ceramic green body is a key for the perfect melt infiltration method. Selective laser sintering (SLS) technology provides a new opportunity for a top grade ceramic forming process, which is rapid and efficient in realizing large-scale and complicated-shape without cast molding. Here, the SiC green body was obtained by SLS technique with thermoplastic phenolic resin as binder and its content lower than 15% (in volume) for the subsequent procedure to fabricate composite materials. However, low binder content results in low flexural strength. As the resin content increases to 25% (in volume), the strength of the SiC green body reaches 3.77 MPa with a strength increment of 702.1% for the SLS SiC green body. Spray drying was applied to form more spherical powder. Nevertheless, the porosity of the SiC green body is still high (71.18%), due to porous microstructure remaining in spray-dried powder, which leads to deteriorated strength of the green body.