氧化锆零件激光选区烧结/冷等静压复合成形技术

氧化锆陶瓷材料以其优异的性能在工业生产中具有极大的应用前景，但由于脆性大、硬度高等原因，复杂形状氧化锆零件往往难以成形和加工。为了获得复杂形状氧化锆陶瓷零件，通过溶剂沉淀法将粘接剂尼龙12覆膜至纳米氧化锆粉末的表面，然后对覆膜后的粉体进行激光选区烧结(Selective laser sintering, SLS)成形，并通过传统的冷等静压(Cold isostatic pressing, CIP)技术对SLS零件进行致密化处理，同时满足氧化锆初坯成形时形状复杂度和密度的要求。通过试验得出在激光能量密度为0.415 J/mm2时，获得的SLS陶瓷件密度较大，对不同激光能量密度制备的SLS陶瓷件进行保压压力为200 MPa的冷等静压致密化处理，根据热脱脂机理以及粘接剂的TG曲线，分别制定了SLS/CIP试样的热脱脂工艺，最后对脱脂试样进行高温烧结，在后续处理的各环节，氧化锆零件的密度仍受SLS成形的影响，但该影响逐渐减弱，SLS/CIP/FS成形件最大相对密度和维氏硬度分别达到了97%和1180 HV1，已接近“模压-烧结”的致密氧化锆陶瓷的性能，在试样断口的扫描电子显微镜(SEM)分析基础上，对氧化锆复合成形的微观演变进行了研究。虽然最终烧结件密度和硬度仍有待提高，但是提出了一种极具潜力的氧化锆零件近净成形工艺方法，为制造高性能复杂形状的陶瓷零件奠定了基础。

Additive Manufacturing of Zirconia Parts via Selective Laser Sintering Combined with Cold Isostatic Pressing

Zirconia has great application prospect for its excellent properties in the industrial production. But due to high brittleness and hardness, complex shape zirconia parts are often difficult to form and machine. To obtain complex zirconia parts, nano-zirconia powder is coated by the binder nylon 12 by solvent precipitation method. Coated powder is then formed via selective laser sintering (SLS) combined with cold isostatic pressing (CIP). Through the experiment, when laser energy density is 0.415 J/mm2, SLS ceramics had the biggest density. The subsequent 200 MPa CIP process is carried out on SLS parts with different laser energy density. According to the thermal debinding mechanism and TG curve of the binder, the reasonable thermal debinding process is formulated respectively. After furnace sintering (FS), with the steps of subsequent processing increased, parts affected by the SLS forming process gradually weakened, the largest relative density and Vickers hardness of SLS/CIP/FS parts are respectively 97% and 1180 HV1, radial and axial shrinkage rate were 58.1% and 67.8% respectively, and fracture of specimens are analysed by scanning electron microscope (SEM). Although the final density and hardness of the ZrO2 are still to be improved, a potential technical method for manufacturing complex zirconia parts with high performance is provided.