Evaluation of frequency dependence of adiabatic compressibility and transition of mechanical behaviors for traction oils

摘要考虑到研究进度，本文的研究成果概述如下：(1)采用金刚石-砧细胞（DAC）建立了高达3 GPa和150 cc的布里渊光散射测量技术。发现了高压密度的频散特性，并推导出在GHz频率范围内，油在室温下表现为弹塑性，随着温度的升高向粘弹性和粘性过渡。(2)在GHz频率附近，用布里渊散射法评价声速的色散。当频率增加两倍时，低粘度液体的频率增加了几个百分点，10 mpa液体的频率增加了10%，1 Pas液体的频率增加了几个百分点。同样，进行了高压下的分散实验，得到了5 GPa下合成润滑油的物理性能。随着压力的增加，分散立即消失，并提出了加载和卸载之间弹性模量存在滞后的可能性。(3)利用超声波仪器，测得的MHz声速值为1500m /s，与油的种类和频率无关。建立了高温测量系统和程序，并进行了高压超声仪器设计的初步实验。(4)布里渊散射结果（GHz）与超声波结果（MHz）的绝热压缩性差异最大可达40%。通过外推Ohno等人提出的润滑油流变机制，估计力学行为的相变高达2 GPa，高压牵引试验结果似乎处于弹塑性区，速度增加与粘度增加具有相似的效果。(5)进行了新的尝试，即利用DAC分析多孔固体材料在极高压力下的摩擦力，DAC类似于含自由体积的润滑剂。

Abstracts of this research results are outlined as follows considering research schedule : (1)Brillouin light scattering measurement technique up to 3 GPa and 150ﾟC was established employing a diamond-anvil cell (DAC). Frequency dispersion of high-presuure density was found out, and it was deduced that, in GHz frequency region, oils behave like elasticplastic at room temperature and transit to viscoelastic and viscous feature with elevating temperature. (2)Around GHz frequency, the dispersion of sound velocity was evaluated by Brillouin scattering. With twice increase of frequency, a few % increase for low viscosity liquids was observed, and 10 % for 10 mPas liquids, and a few % for 1 Pas liquids. Similarly, Dispersion experiment under high pressure was made and physical properties for synthetic lubricants up to 5 GPa were obtained. Dispersion was resulted to disappear immediately with pressure and the possibility of hysteresis of elastic modulus between loading and unloading was proposed. (3)Employing ultra-sonic apparatus, MHz sound velocity measurements gave the value of 1500 m/s independent of the kind of oils and frequency. High temperature measurement system and procedure was established and the preliminary experiment for high pressure ultra-sonic apparatus design was made. (4)The difference of adiabatic compressibility between Brillouin scattering results (GHz) and ultra-sonic results (MHz) was turned out to be at most 40 %. Phase transition of mechanical behavior was estimated up to 2 GPa by extrapolating rheological regime of lubricants proposed by Ohno et al.and high pressure traction test results seemed to be in the elasticplastic region and velocity increase has similar effect as viscosity increase. (5)A new attempt was made, that is, the analysis of frictional force for porous solid materials under very high pressure using DAC,which is similar to lubricants including free volume.