A comprehensive study on the particulate matter characteristics of a friction material containing blast furnace slags

Recent studies have indicated the positive aspects of adding blast furnace (BF) slags on the friction and wear properties of different composite materials. However, the corresponding studies on the extremely important particulate matter (PM) emissions characteristics are seldom explored. This one-of-a-kind study examined the PM characteristics of two types of BF slags in detail. The slags were added in an in-house formulated friction material formulation with limited constituents to highlight the role of the added slags. Pin on disc tests were conducted at a mild wear testing condition with added attachments to the equipment to count and collect emitted particles at different particle size range. A significant reduction in pin wear and collected emitted particles were seen with the slag presence. The friction coefficient of the slag specimens was slightly lower than the reference sample. Through SEM and TEM analysis, it was seen that the slags actively contributed to and supported the formation of smooth, compacted, and extended secondary contact plateaus. From this study, the utilization of slags for specific applications is further evaluated, paving the path for subsequent inclusion/ replacement of conventional constituents in friction material compositions.