Yuan Chengqing

Remote fault diagnostic model for tribological systems in marine diesel engine with two-level self-organizing map network

Many researches indicate that a great number of failures occur in the tribological system which will reduce the reliability of the marine diesel engine. Therefore, it is necessary to monitor the condition and identify the fault mode of the engine. In this paper, remote fault diagnostic technology is developed to take full advantage of the online oil monitoring system and the laboratory analysis for the tribological systems. To increase the efficiency of fault diagnosis, a two-level fault diagnostic model based on self-organizing map (SOM) was established with the oil parameters from the online oil system and the experimental data from the laboratory. Based on the component map of SOM network, the attributes of the feature vector in the second level were reduced to simplify the model and the trajectory of the samples was tracked during the application of the system. The diagnostic result indicates that the remote fault diagnosis technology benefits the full acquirement of the information reflecting the engine condition and the two level fault diagnostic model can be well applied in fault diagnosis for the tribological systems in marine diesel engine with satisfactory result.

Erosion Behaviors of Elastic Polymer Coatings

Two kinds of spray elastic polymer coatings were made of polyiu ethane-urea and pure polyurea. The dynamic mechanical properties of the coatings were measured by the dynamic mechanical analysis(DMA). Their corresponding wear performances were investigated by the Tab er tribo-machine and the high-pressure water jet erosion tester. The topographies of the coatings were observed by the scanning electron microscopy (SEM), the chromatic confocal 3D profiler and the atomic force microscopy (AFM). The elasticity and the relationship between the coatings’ components and their erosion resistances were analyzed as well. The results show that the spray polyurea coating provides with excellent damping properties and anti-wear performance which can be used under the hydraulic condition.

Study on Surface Passivation Treatment and Tribological Properties of 1Cr18Ni9Ti Stainless Steel in Hydrogen Peroxide

The aim of this work is to study the tribological properties of the lCiT8Ni9Ti stainless steel (lCiT8Ni9Ti SS) in different concentrations of hydrogen peroxide. The passivation treatment of lCrl8Ni9Ti SS was conducted at ambient temperature for 6h in solution of up to 45 wt% nitric acid. The characterized techniques, including the electro-chemical measurement system (CS 300) and X-ray photoelectron spectroscopy (PHI5702) were used to study the electrochemical behavior and chemical composition of the passive film on the lCiT8Ni9Ti SS surface. The tribological test of lCrl8Ni9Ti SS/GCiT5 steel rubbing pairs was carried out using a pin-on-disc tribometer. The friction coefficient and wear loss were collected and analyzed. TR240 profilometer, automated 3D non-contact surface analysis (STIL) and scanning electron microscopy (SEM) were employed to measure and observe the surface morphology and microstructure on the worn surfaces of the tested samples. The results indicate that the corrosion resistance of nitric acid passivated lQT8Ni9Ti SS increases significantly due to the existence of passivation film which is mainly composed of chromic oxide. Moreover, the lCiT8Ni9Ti SS passivated with diluted nitric acid exhibits lower friction coefficient and higher wear resistance than impassivated one in hydrogen peroxide. It is estimated that the main wear mechanism is a mixture of adhesive wear, abrasive wear and oxidation wear for the passivated and unpassivated 1Crl8N9Ti SS in different concentration of hydrogen peroxide. However, the adhesive wear experienced a large alleviation in 90% H2O2 compared with other concentration.