Effect of B2O3/SiO2 molar ratio and B2O3 content on viscosity and structure of B2O3–SiO2–Al2O3–Na2O–TiO2 glass lubricant

• Published in: Journal of the American Ceramic Society Vol. 107; no. 8; pp. 5247 - 5264
• Main Authors: Cui, Lei, Lv, Wei, Ni, Pei‐yuan, Wang, Huailiu, Li, Ying
• Format: Journal Article
• Language: English
• Published: Columbus Wiley Subscription Services, Inc 01.08.2024
• Subjects: Activation energy; Aluminum oxide; B2O3 content; B2O3/SiO2 molar ratio; Boron oxides; Degree of polymerization; glass lubricant; Hot extrusion; Hot working; Lubricants & lubrication; melt structure; Silicon dioxide; Titanium; Titanium dioxide; Viscosity
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.19824

Glass lubricant with a suitable viscosity is essential for producing high‐quality titanium products by the hot extrusion process. In this study, a novel lubricant of B2O3–SiO2–Al2O3–Na2O–TiO2 (BSANT) glass was proposed, where the effects of B2O3/SiO2 molar ratio (B/Si) and B2O3 content on viscosity and structure were investigated. The results showed that the BSANT glass viscosity was gradually decreased, and the viscous activation energy was decreased by 20.24% with an increased B/Si ratio from 0.415 to 0.719. This was attributed to the decreased amounts of Q3, [BO4], [AlO4], and bridging oxygen (BO) in the network structure, which in turn resulted in a decreased network degree of polymerization. When B2O3 content was increased from 18.70 to 33.12 mol.%, the melt viscosity value at 950 ℃ was decreased by 64.51%, and the viscous activation energy was reduced by 15.82%. Boron anomalies were also observed in glass melts with the B2O3 content from 28.28 to 33.12 mol.%. The mechanisms responsible for this phenomenon were thoroughly discussed in the study. Additionally, a comparison and discussion of the applications of glass lubricants in metal hot working were presented. A glass lubricant with a specific composition was recommended for use in hot extrusion process within the temperature range of 950–1100°C due to its relatively stable viscosity properties. A novel lubricant of B2O3–SiO2–Al2O3–Na2O–TiO2 (BSANT) glass was proposed, where the effects of B2O3/SiO2 molar ratio (B/Si) and B2O3 content on viscosity and structure were investigated. A glass lubricant with a specific composition was recommended for use in hot extrusion process within the temperature range of 950–1100°C due to its relatively stable viscosity properties.