Babbitt is the most widely known bearing material, named after the invention of American Babbitt, because of its white color, also known as white metal, its application can be traced back to the era of the Industrial Revolution. Tin-based babbitt and lead-based babbitt with friction-reducing properties are the only materials suitable for rotation relative to low-hardness shafts. Compared with other bearing materials, they have better adaptability and press-fit, and are widely used in large Marine diesel engines, turbines, alternators, and other mining machinery and large rotating machinery.
The main components of babbitt are tin, lead, antimony, and copper. Among them, antimony and copper are used to improve the strength and hardness of the alloy. Babbitt alloys can be simply divided into three types: high-tin alloys, high-lead alloys and master alloys (in alloys, both tin and lead occupy an important proportion). In all these alloy systems, antimony and copper serve as important alloying and hardening elements, and their structures are composed of hard, intermetallic compounds dispersed in a soft matrix.
The microstructure characteristic of babbitt is that the hard phase particles are evenly distributed on the soft phase matrix, and the soft phase matrix makes the babbitt alloy have very good embedding, compliance and anti-seizure, and after running in, the soft matrix is in the soft matrix. The concave and convex hard points form a small gap between the sliding surfaces, which becomes an oil storage space and a lubricating oil channel, which is conducive to reducing friction; the convex hard points play a supporting role and are conducive to bearing.
In addition to the manufacture of sliding bearings, babbitt alloys are often used by spraying their wires or powders on steel and other substrates to make bearing bushes because of their soft texture and low strength. In order to prevent component segregation and refine grains, a small amount of arsenic is often added.
According to national standards, babbitt alloys can be divided into tin-based alloys and lead-based alloys. The strength and hardness of lead-based alloys are lower than those of tin-based alloys, and the corrosion resistance is also poor. Therefore, when customers use babbitt alloys, they usually choose tin-based alloys. The commonly used grades are ZChSnSb11-6, ZChSnSb8-4 and so on. Although the performance of lead-based alloy is not as good as that of tin-based alloy, many customers still choose to use it because it is more economical to use. Its commonly used grades are ZChPbSb16-16-2, ZChPbSb1-16-1 and so on.