Abstract
Sliding wear tests of chilled cast iron tappet-disc and cam-ball tribo-partners were conducted by using ball on disc testing device. Magnetron sputtering CrTiAlN hard coating and Graphite like carbon (GLC) solid lubricant coatings were applied on either one or both of the contact surfaces on tribo-partners. Ball crater device and scanning electron microscope were used to investigate surface wear of rubbed track on disc and wear scar on ball. The sliding performances of tribo-partners were evaluated in terms of coefficient of friction at sliding surfaces and specific wear rate (SWR) on both of the rubbed surfaces under specific test conditions. All test results showed that GLC solid lubricant coating on both surfaces of tappet-disc and cam-ball was the best option to allow this tribo-partners having high performance in terms of sliding under high load with low coefficient of friction and low SWR. The advantage of using GLC solid lubricant coating is to enable mechanical parts made of ordinary and sustainable materials (e.g. cast iron or plain steels) to be operated under even harsher conditions of higher load and higher wear environment with improved performance.
Highlights
Graphite like carbon (GLC) solid lubricant coating outperformed CrTiAlN hard coating in terms of whole system performance improvement of the tribo-partners, e.g. tribo-partners sliding with very low coefficient of friction and retaining with very low specific wear rate (SWR) on both contacted surfaces
Sliding performance of chilled cast iron disc/ball tribo-partners was systematically evaluated in terms of coefficient of friction, specific wear rate and load bearing capacities at sliding interfaces
The tribo-partners without coating were conducted high coefficient of friction at sliding interfaces that incorporated to stress on the counterpart surfaces to correspond high abrasive and adhesive wear
Summary
Chilled cast iron materials have been recognized with combined properties of surface hardness and body ductility [1] [2] [3] [4] [5] and considered as one of the most common materials used to make automotive engine components, such. These components are facing increased challenges of working under severe conditions of high power, high speed, high pressure and high load in order to achieve high efficiency, down size and low emissions. There were number of technologies reported [10] [11] [12] to produce low coefficient of friction and wear resistant coatings that improved the performance of automotive parts (such as cam-tappet, piston rings-cylinder linear, valve trains and fuel injection pumps, etc.) made of inexpensive and sustainable materials (e.g. low carbon steel, cast iron, bearing steel and stainless steels, etc.). Comparison of testing results was made to provide an optimum system of coating to tribo-partners from which the best sliding performance was achieved
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