Radiation tolerance of several lithium greases

Abstract

Using γ ray to irradiat six types of lithium grease, the color of these greases was observed to change, and the degree of change was found to be positively correlated with an increase in the absorbed dose. After irradiation with an absorbed dose of 8.1×103 kGy, the thickener of the lithium complex grease softened, degraded, and entered the hardening and crosslinking stage ahead of its ordinary degradation process. Furthermore, its average shear stress increased by 169%. Additional oxidation products were generated from the base oil of the lithium complex grease compared with the simple lithium-based grease treated with the same absorbed dose. When simple lithium grease absorbed a dose of 8.1×103 kGy, its thickener also softened and the consistency decreased; however, its average shear stress decreased. The degree of deterioration of the simple lithium grease was seemingly lighter than that of the lithium complex grease. Therefore, simple lithium grease may be more suitable for irradiation facilities.

Keywords

• lithium-based grease
• irradiation tolerance
• irradiation
• gamma rays