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Copper-free non-asbestos-organic (NAO) brake pads have been developed to satisfy the copper content regulations in North America. Copper-free NAO brake pads are required to have a stable friction coefficient owing to the electrification of the control systems, as well as to exhibit improved wear resistance to reduce brake dust emissions. Our previous study indicated that the transfer film formed on the rotor surface affects both the friction coefficient stability and amount of wear. In this study, we investigated how different types of inorganic fillers affect the transfer film formation and its composition in a wear test controlled by temperature. It was confirmed that the main component of the transfer film was iron oxide derived from the rotor. Furthermore, the contained components changed according to the appearance of the rotor surface after each wear test.

As direct injection technology in gasoline engines has become increasingly sophisticated to seek better performance, even a small amount of deposit can have a negative effect on the functionality of injectors. Against such a background, gasoline with effective additives is expected to fix this issue, however, the clean-up and keep-clean processes are not fully understood. In this study, a direct injector fouling test has been developed in order to inspect in more detail injector fouling phenomena in gasoline engines. The test engine used was a 2012 downsized supercharged direct injection spark ignition (DISI) engine equipped with an injector of maximum 15MPa injection pressure. The test fuel consisted of one regular grade gasoline (RG) and three premium grade gasoline with different concentrations of detergent.

Investigation of both intake valve deposit (IVD) formation tendency and the effect of surrounding conditions (e.g. atmospheric temperature) on IVD formation was conducted using poly aromatics-rich gasoline in a port fuel injected (PFI) engine. The IVD mostly consisted of carbonaceous deposit and this was shown to be derived from the heavier poly aromatic fuel molecules and engine oil. Analysis also indicated that some metals in the deposit structure came from additives of lubricating oil and the wear and/or corrosion within the engine. In this engine test, there was a significant effect of room temperature where higher room temperatures correlated with higher levels of IVDs. These results illustrate the importance of the surrounding condition in order to understand the IVD issues, higher IVDs weights will result under hotter driving (e.g. in summer) condition.