静态热老化对锂-钙基润滑脂微观结构和流变性的影响

采用静态热老化模拟润滑脂在轴承中的热老化过程,通过红外光谱特征波峰面积变化、扫描电镜和差热分析表征热老化后润滑脂微观结构,并采用流变测试仪考察热老化过程中润滑脂流变性能的变化.结果发现：随着老化时间延长,基础油分子碳链发生断裂,稠化剂浓度下降,产生含羰基类氧化产物,该类物质浓度逐渐增强;老化后的润滑脂晶体结构遭到严重破坏,皂纤维网状结构逐渐瓦解,润滑脂结构稳定性变差,剪切过后,结构恢复速率变慢;超过热老化288 h润滑脂热稳定临界点后,润滑脂老化反应加剧,易从润滑部位流失,润滑失效.

The Influence of Static Thermal Degradation on Microstructure and Rheological Properties of Lithium-Calcium Base Grease

Simple static thermal ageing tests have been carried out to simulate the thermal degradation of the Lithium-Calcium base grease used in a rolling element bearing. The microstructure and rheology of Lithium-Calcium base grease after thermal degradation were analyzed by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and rheometer. The results show that both oil and thickener were degraded, i.e. FT-IR absorbance at 1700 cm^-1 and the enhanced strength of absorbance with the increasing aging time, and the gradually destroyed net structures of fiber with chain ruptured, degraded crystal structure of Lithium-Calcium base grease. After ageing time reached the critical value of 288 hours , the ageing of grease accelerated, the stability of the grease structures deteriorated sharply with prolonged ageing time, and the net structures of fiber rebuilt slowly after shearing, resulted that the samples cannot adhere and function well in movable joints with 288 hours ageing.