Electroless nickel plating is widely used as a film having abrasion resistance as well as hard chromium plating. It can deposit film of uniform thickness on catalytic metal and after heat treatment it has almost same hardness of hard chromium plating. I will introduce the variation of electroless nickel plating and its tribological characteristics.
Surface treatment is used for the manufacturing process of automobile parts, and it includes many purposes and kinds. For example, lubricity is demanded from processed material in the forging process, and seizure resistance is necessary for the dies. In addition, wear resistance, fatigue endurance and corrosion resistance are required to automobile parts. Surface treatment includes solid phase, liquid phase, gas phase and plasma process. In this section, we introduce surface treatment using the liquid phase method such as the chemical conversion coating and salt bath nitriding.
The application of dry process technology to piston rings is introduced. The transition of surface treatment technology from the hard chromium plating to DLC coating is explained with the background about improving the performance of piston ring to respond the social requirement such as the improving fuel economy. Finally, the possibility of the applied technology to the future engine components by using the super-lubrication phenomenon by ta-C coating under the environmentally friendly lubricant is discussed.
Thermal spraying is a method of heating a spray material utilizing combustion or electric energy and spraying particles in a molten or semi-molten state onto the surface of the substrate. It has characteristics such as low temperature process, high coating rate, high productivity, wide variety of materials such as metals and ceramics can be used and coating on large products is also possible, etc. In recent years, practical use in the industrial field such as aero, power generation, automotive, etc. is increased. On the other hand, there are some problems in the coating performance, such as pores and oxides remain in the coating. These problems have been overcoming by the development of low pressure plasma spray and HVOF technology and are also being applied to chromium plating alternative applications which are required to have dense structure for corrosion resistance. New attempts have also progressed to get a higher performance and develop new coating. In this paper, basic knowledge and latest trend of thermal spray process are described.
Along with the recent progress of automobiles and industrial machinery, needs for high-function lubricants have also been increasing. The needs are promoting introduction of non-conventional materials and approaches to research and development of lubricants. They include, for example, cellulose nanofibers as a grease thickener and thickener observation techniques with a confocal laser scanning fluorescence microscope and micro-Fourier transform infrared spectrometer. Also, computational chemistry is growing in usage to analyze tribochemical phenomena of lubricants. This article outlines the recent trends of lubricant research and development.
Recent years, the viscosity of motor oils gets lower in order to decrease resistance in the fluid lubrication region. On the other hands, friction in the boundary lubrication region increases, and this causes the possibility of seizure. In such circumstance, MoDTC is widely used as friction modifier to reduce friction in boundary lubrication. But it is well known that the low friction effect of MoDTC is depending on the conditions such as metal composition. So, it is required to understand the reason why metal composition affects reactivity of MoDTC. For this objective, we tried to appear the mechanism why tribo-film structure is different by metal composition. As a result of analysis of tribo-film structure on some kind metal substrate, the structure of low friction tribo-interface is clarified as follows; as the amount of Cr in metal substrate increases, the thickness of tribo-film is thinner. And Cr oxide exists at the interface between the Cr rich substrate and the tribo-film. So we considered that the oxidation of Cr affects the ease of decomposition of MoDTC and the thin film thickness, because Cr is easily to oxidize and Cr forms passive film. From this consideration, we made clear that making use of Cr rich metals can obtain low friction in MoDTC contained oil.