Preliminary Investigation Into Comparative Performance of Titanium Based Coatings for Automotive Applications Using Biodiesel Blend and Diesel

In order to reduce emissions and improve performance, engine designers have increased fuel injection pressures to improve fuel atomization. This leads to increased mechanical loads on the injection system requiring finer clearances that must be maintained between the plungers and bores in order to maintain diesel fuel injection quality. The reduction in diesel fuel sulfur levels required for meeting the emission legislations result in decreased fuel lubricity. In addition, due to unprecedented rise in the crude oil prices, biofuels are getting increasing attention worldwide. However, this also needs evaluation of the performance of the engine parts, especially the friction and wear in injection systems. In the present study we have investigated three titanium based physical vapour deposition (PVD) coatings (TiN, TiAlN, TiCN) used in two different environments namely mineral diesel and biodiesel, both containing 1% water. Commercially available thin-film ion-bonded coatings of above mentioned inter-metallic compounds, grown on steel balls were subjected to wear under stable load conditions in a custom build rotating disk wear tester. Some of the interesting findings of this experimental investigation may be instrumental in providing input for the development of hard, corrosion-resistant coatings for parts of Injector and fuel pumps of internal combustion engines using different fuels, especially biodiesel fuels.Copyright © 2006 by ASME