Injection Molding Process of Silicon Nitride Ceramics

Abstract

Abstract: With the combination of injection molding and gas pressure sintering, ceramic shaped parts with small size and high precision can be prepared in large quantities at low cost. In this paper, low density polyethylene (LDPE) and ethylene-vinyl acetate copolymer (EVA) were used as binders to prepare silicon nitride green bodies under injection temperature of 165 ℃ and injection pressure of 85 MPa. The complete silicon nitride injection molding process route was obtained by thermal degreasing process and sintering kinetics test. The effect of feedstock solid content on green body density, sintering density and Vickers hardness and the non-Newtonian index change of feedstock at 140~160 ℃ were studied. The results show that the optimum solid content of feedstock is 52.42% (volume fraction). The density of silicon nitride injection green body prepared under this condition is 2.10 g/cm³, the sintering density is 3.23 g/cm³, and the Vickers hardness is (15.24±0.34) GPa. The non-Newtonian index of feedstock is smallest at 160 ℃, that is, the rheological of feedstock is the best at this temperature.

Key words: silicon nitride, injection molding, binder, solid content, thermal degreasing, pressure sintering, Vickers hardness

CLC Number:

TQ174.75

SHEN Changsheng, WANG Ruiqiang, LI Bin, WEI Zhonghua, CHEN Song, CHEN Bo, WANG Weiguo, ZHANG Weiru. Injection Molding Process of Silicon Nitride Ceramics[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2023, 42(8): 2915-2921.

References

[1] 陈波, 韦中华, 李镔, 等. 氮化硅陶瓷在四大领域的研究及应用进展[J]. 硅酸盐通报, 2022, 41(4): 1404-1415.
CHEN B, WEI Z H, LI B, et al. Research and application progress of silicon nitride ceramics in four major fields[J]. Bulletin of the Chinese Ceramic Society, 2022, 41(4): 1404-1415 (in Chinese).
[2] 谢志鹏. 结构陶瓷[M]. 北京: 清华大学出版社, 2011: 148-150.
XIE Z P. Structural ceramics[M]. Beijing: Tsinghua University Press, 2011: 148-150 (in Chinese).
[3] 申常胜, 李镔, 韦中华, 等. 陶瓷注塑成型技术的研究与进展[J]. 中国陶瓷工业, 2022, 29(5): 24-29.
SHEN C S, LI B, WEI Z H, et al. Research and development of ceramic injection molding[J]. China Ceramic Industry, 2022, 29(5): 24-29 (in Chinese).
[4] FAYYAZ A, MUHAMAD N, SULONG A B, et al. Micro-powder injection molding of cemented tungsten carbide: feedstock preparation and properties[J]. Ceramics International, 2015, 41(3): 3605-3612.
[5] 温佳鑫. 氧化锆陶瓷注射成型无毒性溶剂脱脂粘结剂体系研究[D]. 北京: 北京科技大学, 2017: 35-40.
WEN J X. Fundamental study on the binder system eliminated by no-toxic solvent used in zirconia ceramic injection molding[D]. Beijing: University of Science and Technology Beijing, 2017: 35-40 (in Chinese).
[6] WEN J X, XIE Z P, CAO W B, et al. Effects of different backbone binders on the characteristics of zirconia parts using wax-based binder system via ceramic injection molding[J]. Journal of Advanced Ceramics, 2016, 5(4): 321-328.
[7] YANG S D, ZHANG R J, QU X H. X-ray analysis of powder-binder separation during SiC injection process in L-shaped mould[J]. Journal of the European Ceramic Society, 2015, 35(1): 61-67.
[8] LIU D M, TSENG W J. Influence of debinding rate, solid loading and binder formulation on the green microstructure and sintering behaviour of ceramic injection mouldings[J]. Ceramics International, 1998, 24(6): 471-481.
[9] 王波, 林枞. 粉末固含量对ZTA陶瓷注射成型的影响[J]. 硅酸盐通报, 2013, 32(1): 108-112.
WANG B, LIN C. Influence of solid loading on injection molding of ZTA ceramic[J]. Bulletin of the Chinese Ceramic Society, 2013, 32(1): 108-112 (in Chinese).
[10] GERMAN R. 粉末注射成形[M]. 曲选辉译. 长沙: 中南大学出版社, 2001: 117-119.
GERMAN R. Powder injection molding[M]. QU X H trans. Changsha: Zhongnan University Press, 2001: 17-119 (in Chinese).
[11] YANG X F, YANG J H, XU X W, et al. Injection molding of ultra-fine Si₃N₄ powder for gas-pressure sintering[J]. International Journal of Minerals, Metallurgy, and Materials, 2015, 22(6): 654-659.
[12] 梁叔全, 黄伯云. 粉末注射成形流变学[M]. 长沙: 中南大学出版社, 2000.
LIANG S Q, HUANG B Y. Powder injection molding rheology[M]. Changsha: Central South University Press, 2000 (in Chinese).
[13] HANEMANN T. Influence of particle properties on the viscosity of polymer-alumina composites[J]. Ceramics International, 2008, 34(8): 2099-2105.
[14] LII D F, HUANG J L, LIN C H, et al. The effects of atmosphere on the thermal debinding of injection moulded Si₃N₄ components[J]. Ceramics International, 1998, 24(2): 99-104.
[15] HRDINA K E, HALLORAN J W, OLIVEIRA A, et al. Chemistry of removal of ethylene vinyl acetate binders[J]. Journal of Materials Science, 1998, 33(11): 2795-2803.
[16] 秦笑威, 谢志鹏, 姚依旦, 等. 氮化硅陶瓷的烧结技术及其应用进展[J]. 陶瓷学报, 2022, 43(6): 971-986.
QIN X W, XIE Z P, YAO Y D, et al. Progress in sintering technology and applications of silicon nitride ceramics[J]. Journal of Ceramics, 2022, 43(6): 971-986 (in Chinese).
[17] 李镔, 张伟儒, 韦中华, 等. 氮化硅陶瓷中压注塑成型技术(MPIM)研究及进展[J]. 中国陶瓷工业, 2021, 28(1): 27-37.
LI B, ZHANG W R, WEI Z H, et al. Research and development of medium pressure injection molding technology (MPIM) of silicon nitride porcelain[J]. China Ceramic Industry, 2021, 28(1): 27-37 (in Chinese).