Babbitt metal is a low melting point soft alloy widely used on the surface of sliding bearings. It is a metal material composed of tin, lead, antimony and copper as the main elements. Its characteristics include good embedding, compliance and anti-seizure properties, which can protect the journal under high load and low-speed operation conditions, reduce wear and improve the stability and life of equipment operation.
According to the main matrix elements, babbitt alloys can be divided into two categories: tin-based and lead-based.
Tin-based Babbitt alloys have tin (Sn) as their main constituent, typically with approximately 7%-12% antimony (Sb) and 2%-5% copper (Cu). Small quantities of cadmium (Cd), arsenic (As) or other elements are sometimes added to improve performance. SnSb11Cu6 is a typical grade. Antimony and copper form hard intermetallic compounds such as SbSn and Cu6Sn5, dispersed as fine particles in the softer tin-based solid solution. This produces the characteristic structure of a soft matrix containing hard particles.
This structure is conducive to the formation of micro-oil storage pits during operation, reducing the friction coefficient and effectively bearing pressure.
Lead-based Babbitt alloy uses lead (Pb) as the matrix and usually contains antimony 10%-15%, tin 5%-10% and a small amount of other elements. Common brands such as PbSb15Sn10. This type of alloy is relatively low cost and is often used in medium load conditions. In its structure, tin and antimony form a SnSb compound, which acts as a strengthening phase, while the lead matrix provides good plasticity.
The selection of the two types of alloys requires comprehensive consideration of load, speed, corrosive environment and cost factors. Tin-based Babbitt alloys have better corrosion resistance and mechanical properties and are often used in important equipment; lead-based alloys are mostly used in general industrial applications.
In actual sliding bearing manufacturing, babbitt alloy is usually poured or plated on the inner surface of the bearing shell in a thin layer to form a good tribological system. The control of its component proportions and the stability of the smelting process have a key impact on performance.
(Source: Hunan Bohou New Materials Co., Ltd.)