In the manufacturing of bulk graphite, pores produced by vaporization and discharge of volatile materials in binders during carbonization reduce the density of bulk graphite, which adversely affects the electrical conductivity, strength and mechanical properties. Therefore, an impregnation process is introduced to fill the pores and increase the density of bulk graphite. In this study, bulk graphite is prepared by varying the viscosity of the impregnant. The microstructure of bulk graphite is observed. The flexural strength and electrical resistivity are measured. As the viscosity of the impregnants decreases and the number of impregnations increases, it is shown that the number of pores decreases. The density before impregnation is 1.62 g/cm3. The density increases to 1.67 g/cm3 and porosity decreases by 18.6 % after three impregnations using 5.1 cP impregnant, resulting in the best pore-filling effect. After three times of impregnation with a viscosity of 5.1 cP, the flexural strength increases by 55.2 % and the electrical resistivity decreases by 86.76 %. This shows that a slight increase in density due to the pore-filling effect improves the properties of bulk graphite.

Abstract
1. Introduction
2. Experimental Procedure
    2.1 Raw materials and preparations
    2.2 함침공정
    2.3 미세조직 분석
    2.4 굴곡강도 측정
    2.5 Electrical Resistivity measurement
3. Results and Discussion
    3.1 Raw materials 분석
    3.2 미세조직 분석
    3.3 굴곡강도 분석
    3.4 Electrical Resistivity 분석
4. Conclusions
References

• 이상민(금오공과대학교 신소재연구소) | Sang-Min Lee (Advanced Material Research Center, Kumoh National Institute of Technology)
• 이상혜(금오공과대학교 신소재공학과) | Sang-Hye Lee (School of Materials Science and Engineering, Kumoh National Institute of Technology)
• 노재승(금오공과대학교 신소재공학과) | Jae-Seung Roh (School of Materials Science and Engineering, Kumoh National Institute of Technology) Corresponding author