造孔剂种类对数字光处理成形多孔Si_(3)N_(4)陶瓷性能的影响

Effect of Pore-forming Agent Type on the Properties of Porous Si_(3)N_(4)Ceramics Prepared by Digital Light Processing

多孔Si_(3)N_(4)陶瓷由于其优秀的性能而被应用于航空航天等领域,添加造孔剂法是一种有效制备多孔Si_(3)N_(4)陶瓷的方法。采用数字光处理(Digital light processing,DLP)技术结合添加造孔剂法制备多孔Si_(3)N_(4)陶瓷,系统地研究了淀粉、稻壳粉、聚苯乙烯(PS)、聚甲基丙烯酸甲酯(PMMA)四种造孔剂对多孔Si_(3)N_(4)陶瓷性能的影响规律。研究表明,造孔剂粉体颗粒比表面积的不同对浆料黏度有所影响,其中,稻壳粉比表面积最大,其浆料黏度最小。同时,陶瓷浆料中固相含量的升高会导致固化深度降低;而固体颗粒的平均粒径增大会降低对紫外光的散射,使固化深度升高。此外,造孔剂的物理性质与形态差异会对素坯与烧结样品的微观形貌产生影响,但不影响多孔Si_(3)N_(4)陶瓷的相转变过程与断裂方式。多孔Si_(3)N_(4)陶瓷的抗弯强度随着孔隙率的增加而减小,而孔隙率则与造孔剂自身的物理性质和所形成孔隙的特点密切相关。综合考虑不同造孔剂对陶瓷浆料黏度和固化深度以及DLP打印素坯的质量与烧结样品性能的影响,选用PMMA造孔剂比较合适。添加10%PMMA作为造孔剂时,多孔Si_(3)N_(4)陶瓷的综合性能较好,体积密度为2.66 g/cm^(3),孔隙率为20.10%,抗弯强度为463.43 MPa。

Porous Si_(3)N_(4) ceramics were widely used in aerospace and other fields due to their excellent properties.Adding pore-forming agent is an effective method to prepare porous Si_(3)N_(4) ceramics.Porous Si 3N4 ceramics are prepared using digital light processing(DLP)technology combined with pore forming agent method,and the effects of four pore-forming agents(starch,rice husk powder,polystyrene(PS)and polymethyl methacrylate(PMMA))on the properties of porous Si 3N4 ceramics are systematically investigated.It is shown that the difference in the specific surface area of the pore-forming agent powder particles had an effect on the viscosity of the slurry,among which the rice husk powder had the largest specific surface area and its slurry viscosity is the smallest.Meanwhile,the increase of the volume fraction of solid particles in the ceramic slurry led to a decrease in the depth of cure;while an increase in the average particle size of solid particles reduced the scattering of ultraviolet light,resulting in an increase in the depth of cure.In addition,the difference in physical properties and morphology of the pore-forming agent affected the micro-morphology of the green body and the sintered samples,but would not affect the phase transition process and fracture mode of the porous Si_(3)N_(4) ceramics.The flexural strength of porous Si_(3)N_(4) ceramics decreased with the increase of porosity,which was closely related to the physical properties of the pore-forming agent and the characteristics of the formed pores.Considering the influence of different pore-forming agents on the viscosity and curing depth of ceramic paste,the quality of body green and the properties of sintered sample,it was more appropriate to choose PMMA as the pore-forming agent.The addition of 10 wt%PMMA as the pore-forming agent resulted in a better overall performance of porous Si_(3)N_(4) ceramics with a bulk density of 2.66 g/cm^(3),a porosity of 20.10%,and a flexural strength of 463.43 MPa.