세라믹 적층 제조를 위한 광경화성 모노머 시스템 및 분말 특성에 관한 연구

Abstract

고밀도 및 고정밀 적층 세라믹 제조는 높은 고형분 함량 및 저점도의 광경화성 슬러리를 필요로 한다. 저점도의 단관능기 모노머와 높은 반응성의 다관능기 모노머가 가지는 각각의 장점을 활용하고자 아크릴레이트계 단일 모노머들(2-HEA, 2-HEMA, 1,6-HDDA, BPAEDA, TMPTA)과 이를 혼합한 복합 모노머들의 점도를 확인하였다. 광개시제인 Phenylbis(2,4,6-trimethyl-benzoyl) phosphine oxide(BAPO)와 Diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide(TPO)를 각각 첨가하여 단일 모노머(single monomer)와 복합 모노머(binay monomer)들의 광중합율과 경화 두께를 분석하였다. 이로부터 최적의 복합 모노머 조성을 2-HEA:1,6-HDDA=6:4 로 정의하였다. 최적 조성 모노머 시스템에 알루미나 분말의 입도 분포(2 μm:100 nm=7:3, 4 μm:400 nm=6:4)와 분산제 첨가량을 최적화 하여 조형 가능한 점도 및 높은 광중합율을 갖는 50 vol.% 슬러리를 제조하였다. 알루미나의 입도 분포 및 모노머 시스템이 DLP 3D printing 공정에 미치는 영향을 분석하기 위해 4 종 (Slurry 4B, 4S, 2B, 2S) 의 50 vol.% 광경화성 알루미나 슬러리로 허니컴 구조(honeycomb structure) 시편을 조형하였다. 광조형 시편의 TGA 분석을 통하여 탈지 공정을 최적화하고 4 종의 허니컴 시료(4B, 4S, 2B, 2S)를 최고 온도 1600 ℃ 에서 소결하였다. 2 μm:100 nm=7:3 의 혼합 알루미나를 사용한 2B와 2S 소결체는 4B와 4S 소결체(4 μm:400 nm=6:4) 보다 높은 상대 밀도를 나타내었다. 2 μm와 100 nm 의 혼합 알루미나와 복합 모노머(2-HEA:1,6-HDDA=6:4)를 사용한 2B 소결체의 상대 밀도는 82.41 % 로 가장 높았다. 또한 2B 소결체의 X, Y, Z 축의 수축률은 11.05 %, 17.01 %, 21.27% 로 가장 크게 수축하였다.

The manufacture of high-density and high-precision ceramics by additive manufacturing requires photocurable slurries with high solids content and low viscosity. In order to utilize the advantages of each of the low-viscosity monofunctional monomers and the high reactive multifunctional monomer, the viscosity of acrylate-based single monomers(2-HEA, 2-HEMA, 1,6-HDDA, BPAEDA, TMPTA) and mixtures of monomers was confirmed. The photopolymerization rate and curing depth of single monomers and binary monomers were analyzed by adding Phenylbis(2,4,6-trimethyl-benzoyl) phosphine oxide(BAPO) and Diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide(TPO), which are photoinitiators, respectively. From this, the optimal binary monomer composition was defined as 2-HEA:1,6-HDDA=6:4. By optimizing the particle size distribution of the alumina powder and the amount of the dispersant added to the optimal monomer system, a 50 vol.% slurry having a printable viscosity and a high photopolymerization rate was prepared. To analyze the effect of alumina particle characteristics (particle size distribution) and the monomer system on the DLP 3D printing process, honeycomb structure specimens were printed using four photocurable alumina slurries (Slurry 4B, 4S, 2B, 2S) at 50 vol.%. The debinding process was optimized through TGA analysis of photocured specimens, and four types of honeycomb specimens(4B, 4S, 2B, 2S) were sintered at a maximum temperature of 1600 °C. 2B and 2S sintered bodies using alumina (2μm:100nm=7:3) showed higher relative density than 4B and 4S sintered bodies(4 μm:400 nm=6:4). The relative density of 2B sintered body using alumina (2μm:100nm=7:3) and binary monomer(2-HEA:1,6-HDDA=6:4) was the highest at 82.41%. In addition, the X, Y, and Z-axis shrinkage rates of the 2B sintered body was the highest at 11.05%, 17.01%, and 21.27%.

ABSTRACT Systematic Study of Photocurable Monomer Systems and Powder Characteristics for Ceramic Additive Manufacturing Jin Hyun Kim Directed by prof. Doo Seok Jung, Ung Soo Kim Division of Advanced Materials Science and Engineering Graduate school, Hanyang University

The manufacture of high-density and high-precision ceramics by additive manufacturing requires photocurable slurries with high solids content and low viscosity. In order to utilize the advantages of each of the low-viscosity monofunctional monomers and the high reactive multifunctional monomer, the viscosity of acrylate-based single monomers(2-HEA, 2-HEMA, 1,6-HDDA, BPAEDA, TMPTA) and mixtures of monomers was confirmed. The photopolymerization rate and curing depth of single monomers and binary monomers were analyzed by adding Phenylbis(2,4,6-trimethyl-benzoyl) phosphine oxide(BAPO) and Diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide(TPO), which are photoinitiators, respectively. From this, the optimal binary monomer composition was defined as 2-HEA:1,6-HDDA=6:4. By optimizing the particle size distribution of the alumina powder and the amount of the dispersant added to the optimal monomer system, a 50 vol.% slurry having a printable viscosity and a high photopolymerization rate was prepared. To analyze the effect of alumina particle characteristics (particle size distribution) and the monomer system on the DLP 3D printing process, honeycomb structure specimens were printed using four photocurable alumina slurries (Slurry 4B, 4S, 2B, 2S) at 50 vol.%. The debinding process was optimized through TGA analysis of photocured specimens, and four types of honeycomb specimens (4B, 4S, 2B, 2S) were sintered at a maximum temperature of 1600 °C. 2B and 2S sintered bodies using alumina (2μm:100nm=7:3) showed higher relative density than 4B and 4S sintered bodies(4 μm:400 nm=6:4). The relative density of 2B sintered body using alumina (2μm:100nm=7:3) and binary monomer(2-HEA:1,6-HDDA=6:4) was the highest at 82.41%. In addition, the X, Y, and Z-axis shrinkage rates of the 2B sintered body was the highest at 11.05%, 17.01%, and 21.27%.