Significantly Enhanced Density and Mechanical Strength of Carbon/Graphite Blocks by Waste Gas Pressurized Sintering.

Abstract

Carbonization under pressure is crucial for enhancing carbon/graphite materials. However, conventional pressure sintering, relying on mechanical or external gas pressure, often results in incomplete densification and structural defects due to uncontrolled volatile gas release. Herein, high-density and high-strength self-sintered carbon block in enclosed-space (SCB-E) are produced using waste gas pressurization (WGP) derived from green petroleum coke (GPC). This method can enhance the formation of C─O─C and C═O bonds by promoting dehydration polymerization reaction, which induces interfacial bonding in the carbonization process. Consequently, a decreased mass loss, increased volume shrinkage, and reduced porosity are observed, thereby endowing the obtained SCB-E with significantly improved density and mechanical strength. Specifically, the compressive and flexural strengths of SCB-E are 6.36 and 5.77 times higher than SCB-O sintered in open-space, respectively, while the corresponding graphite block (SG-E) achieves 7.74 and 4.58 times greater compressive and flexural strengths than SG-O. Notably, WGP not only enhances the yield of crack-free carbon blocks and supports scale-up production but also integrates seamlessly with traditional kneading processes to produce high-density, high-strength carbon blocks (CB-E). The current approach offers an innovative and important platform for enhancing the density and mechanical properties of bulk materials.