Research On Lubricating Oil And N-alkanes At Different Temperatures With Terahertz Time-domain Spectroscopy Technology

In this paper,using transmission terahertz time-domain spectroscopy system,the lubricating oil of different low temperature viscosity grades and n-alkenes carbon number of 11-16 with a purity of more than 99% were studied at different temperatures.The main contents are as following:1.Lubricating oil of 5w-40,10w-40,15w-40 viscosity grade were measured by a transmission terahertz time-domain spectroscopy system,The formula of the phase delay of terahertz wave with the temperature change was obtained and the refractive index of the sample in the terahertz wave band with the law of exponential change of temperature was calculated.As the temperature decreased,the wax crystal precipitation in the lubricating oil,and the refractive index of the sample increased which leads to phase delay of terahertz wave.2.The wax in the lubricating oil is a hydrocarbon mixture,in which the proportion of normal paraffin hydrocarbons is between 90%~92%.The temperature dependent phase transition process of the gradual melting of normal paraffin(C11-16)with temperature was studied by terahertz time domain spectroscopy(THz).With the increase of temperature,the terahertz time domain spectroscopy has a very good response to the phase transition from solid to liquid.The time delay of the solid phase and the frequency domain spectral area of the solid liquid mixed solution phase were both have a linear.