Piezosensors for Monitoring Degradation of Automotive Engine Oil ALI JASIM MOHAMMED, MARWA ABDUL MUHSIEN HASSAN Department of Physics, College of Science, Al-Mustansiriyah University, Baghdad, Iraq. E-mail: spiritjabir@yahoo.com E-mail: marwa_alganaby@yahoo.com Abstract Effect of heating times on piezoelectric sensing of engine oil has been investigated with different heating times (0, 15, 30, 45 and 60) min. Sensing signals (piezoelectric) characterized and achieved by using transducer which transmits a mechanical waves towards the glucose solution cell, and then the receptor received the attenuated signals. The range of operating frequencies was (950 kHz - 50MHz), the results of measurement which included recording the resonance frequencies (in the first order) for all prepared samples. The results showed that the resonance frequency shifted to the higher values (from 12MHz to 26MHz) for heating times (from 0 to 60 min) of engine oil. Key words: engine oil, piezoelectrical properties, resonance frequency, Damping Coefficient. BACKGROUND Internal combustion engines in automobiles and other vehicles can only perform efficiently if there is proper lubrication between moving parts. Automotive engine oil is a mixture of base stock, and a number of additives which improve the operational properties of the lubricating oil [1]. Engine oils are susceptible to degradation by oxygen, increased temperature, and shear stress. The degradation of oil is very complex process and affects mainly additives and afterwards, oxidation of the base stock leads to formation of different acidic products, especially carbonic acids, and polymerization processes. The reduced lubrication capabilities caused by inadequate oil viscosity will damage the engine [2]. Thus, there is a need to design a sensor device which can tell us about chemical oil quality, by monitoring these directly in the oil. A variety of sensor devices have been proposed to monitor the degradation based on different parameters such as viscosity [3], conductivity [4], and acidity [5]. Further improvements were carried out by introducing molecular recognition properties in sensitive layers to determine the chemical quality of engine oil in gas or liquid phase by employing mass sensitive transducers [6-8]. Recently, dielectric spectroscopy has also been employed to detect the age of used engine oil [9]. In this paper, we have analyzed the piezoelectric properties of Engine oil. EXPERMINTAL WORK The material used in this paper is (super diesel engine oil meets API service CF, produced and packaged by petromin corporation, Saudi Arabia) at 90 o C heating temperature with different heating times. The effect of heating times (0, 15, 30, 45 and 60) min on piezoelectric sensing of engine oil was measured. The setting used in this paper include a standard two piezo-crystals (Model number: 3B12+9.0EAWC, Type: Piezoelectric Ceramics, Material: Piezoceramics, Metal type: Brass, Electrode form: (Thin) Diode, Connection terminal: Soldier wire or not, Parameter value: (D=12mm, T=0.15mm and f=9 kHz)) located tightly on the copper foil as a diaphragm shown in Fig. (1). RESULTS The resonance frequency can be determined by measuring the output voltage as a function of frequency as shown in Fig. (2), we can observed that the resonance value varied as the frequency sweept from 950 kHz to 50 MHz at different heating times and fixed teamperature at 90 o C, this varied can be due to a number of reasons, such as humidity, atmospheric pressure and mechanical loading. The effect of heating times on resonance frequency can be seen in Fig. (3). Fig. 1: Image of piezo-crystal used in this work. IMCS 2012 – The 14th International Meeting on Chemical Sensors 900 DOI 10.5162/IMCS2012/P1.2.5