Microstructural Characteristics in Babbitt Coatings Deposited by LPCS

Abstract

Studies have already established that the mechanical properties of Babbitt coatings significantly depend on the microstructural characteristics, such as the amount and distribution of intermetallic compounds dispersed in a soft solid solution matrix. For Sn–Sb–Cu-based Babbitt coatings, the formation of SbSn- and CuSn-based precipitates has a substantial influence on the resulting microhardness and thus determines the maximum load carrying capacity. Thermal spraying of Sn-based Babbitt coatings results in a relatively more refined structure of these precipitates than in common manufacturing processes, such as casting, due to the thermal processing conditions. This study aims to evaluate the effect of the temperature of the propellant gas and substrate temperature on the microstructural characteristics of Sn–Sb–Cu-based Babbitt coatings deposited by low pressure cold spraying (LPCS). The deposits were examined for their phase composition, microhardness and mesoscopic structure. It was found that the coatings were mainly composed of Sb2Sn23, Sb0.49Sn0.51 and Sorosite (CuSn or CuSb0.115Sn0.835), regardless of the substrate temperature or temperature of the propellant gas to be investigated. For a gas temperature above 300 °C, an increased microhardness was observed, which correlates with the appearance of a more homogenous distribution of Sb0.49Sn0.51 dispersed in a soft Sn-rich solid solution matrix.

Investigation of the Properties of Anti-Friction Coatings Deposited with Different Casting Methods

“…contacting surfaces experience high friction, such as in bearings or other sliding surfaces [14,[49][50][51]. Another important aspect is that Sb promotes the formation of a fine-grained structure in the coating, which contributes to the mechanical strength, crack resistance and wear resistance [52,53].…”

“…Sb adds hardness to the Babbitt alloy coating and increases its wear resistance [45][46][47][48]. This factor is critical in applications where the contacting surfaces experience high friction, such as in bearings or other sliding surfaces [14,[49][50][51].…”

“…Babbitt’s good damping properties help reduce vibration and noise in rotating machinery. When applying Babbitt alloy coatings, various spraying technologies can be selected, including low-pressure cold spray technology, arc spray technology, flame spray technology, and thermal spray technology [ 11 , 12 , 13 , 14 ]. However, studies have shown that the interface between the coating and substrate is mechanically bonded in coatings fabricated via cold spraying or thermal spraying, which peel off at high temperatures or under relatively high loads [ 15 ].…”

“…Sb adds hardness to the Babbitt alloy coating and increases its wear resistance [ 45 , 46 , 47 , 48 ]. This factor is critical in applications where the contacting surfaces experience high friction, such as in bearings or other sliding surfaces [ 14 , 49 , 50 , 51 ]. Another important aspect is that Sb promotes the formation of a fine-grained structure in the coating, which contributes to the mechanical strength, crack resistance, and wear resistance [ 52 , 53 ].…”