An Experimental Evaluation of Tribological Morphological Excellence for LTB Alloys

LTB(leaded tin bronze) alloys are popular for bush bearing, impeller, and sand guard of submersible, HSC(half split casing), and end suction centrifugal pump sets. Morphological study by OEM(optical emission microscope) of sand-cast different composition mixed LTB alloys shows that the percentage of Sn element in the composition is a deciding factor for the appearance of α, ẞ &δ phases in the copper matrix. α-phase formation will occur up to wt.8% of Sn, α phase formation with nucleation of ẞ phase occurs between 8-9% of Sn, ẞ phase occurs for 9-12% of Sn, ẞ phase with nucleation of δ phase occurs after 12% of Sn, and significant δ phase is visible at 14.5% of Sn. The hardness of LTB alloys increases with the addition of Sn%, provided that the increment of Pb% works as a softening agent between 3.5-14.5% of Sn. The developed hardness model for BHN (Brinell Hardness Number) of LTB alloys has performed well, with an average error of ±9.5%. The highest wear resistance was found as 3.89x10^5 gm/m and COF of 0.505 at 1500 rpm and 50 N normal load for LTB6 alloy.