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The bearing materials used in water pumps are mainly divided into two categories: metallic materials and non-metallic materials. Metal materials: Commonly used sliding bearing materials include bearing alloys (also known as Babbitt alloys or white alloys), wear-resistant cast irons, copper-based and aluminum-based alloys. 1. Bearing alloy: The main alloying elements of bearing alloy (also known as babbitt alloy or white alloy) are tin, lead, antimony, and copper. Antimony and copper are used to increase the strength and hardness of the alloy. According to standards, babbitt alloys can be divided into tin-based alloys and lead-based alloys. Lead-based alloys have lower strength and hardness than tin-based alloys, and their corrosion resistance is also poorer. Therefore, when using babbitt alloys, tin-based alloys are typically chosen; common grades include ZSnSb11Cu6, ZSnSb8Cu4, and others. Although the performance of lead-based alloys is not as good as that of tin-based alloys, they are still chosen for use under the required operating conditions due to their cost-effectiveness. Common grades include ZPbSb16Sn16Cu2, among others. However, the melting points of the elements in bearing alloys are generally low, so they are suitable for operating conditions below 150°C. 2. Copper-based alloys: Copper-based alloys possess high thermal conductivity and better wear resistance compared to steel. Moreover, copper-based alloys possess excellent workability and lubricity; their inner walls can be finely processed to make smooth contact with the shaft surface. The copper-based alloys used as materials for sliding bearings mainly include: brass, which consists primarily of copper and antimony; bronze, which is composed mainly of copper and tin; and copper-lead alloys (also known as lead bronze). Copper-based alloys have high strength, good thermal conductivity and wear resistance, and allow higher operating temperatures than babbitt alloys; however, they lag behind babbitt alloys in terms of ductility, embeddability, and friction compatibility. Commonly used tin-bronze alloys containing tin and phosphorus are suitable for bearings that are subject to medium-speed, heavy loads or impact loads; tin-bronze alloys containing tin, zinc, and lead are suitable for bearings with medium speed and moderate loads. Non-metallic materials 1: Polytetrafluoroethylene possesses good self-lubricating properties and high thermal stability. It has a low coefficient of friction, does not absorb water, is non-sticky, and is non-flammable; it can be used at temperatures ranging from -180 to 250°C. However, it also has disadvantages such as a high linear expansion coefficient, poor dimensional stability, and poor thermal conductivity. To improve its performance, it can be reinforced by filling with metal particles, fibers, graphite, and inorganic materials. 2. Graphite is an excellent self-lubricating material; its ease of processing and the fact that it becomes smoother as it is worn make it a suitable material for bearings. However, its mechanical properties are poor, with weak impact resistance and load-bearing capacity, making it suitable only for light-load applications. To improve its mechanical properties, fusible metals with good wear resistance are often used for impregnation treatment. Common impregnation materials include babbitt alloy, copper alloy, and antimony alloy, among others. Graphite bearings impregnated with babbitt alloy can operate at temperatures ranging from 120 to 180°C; those impregnated with copper alloy can handle temperatures up to 300°C, while graphite bearings impregnated with antimony alloy can operate at temperatures as high as 500°C. 3. Rubber is made from polymers of elastomers and possesses good elasticity and vibration-damping properties. However, it has poor thermal conductivity, is difficult to process, its allowable operating temperature is below 65°C, and it requires circulating water for continuous lubrication and cooling; therefore, it is rarely chosen. 4. Cemented carbide possesses a range of excellent properties such as high hardness, wear resistance, good strength and toughness, heat resistance, and corrosion resistance. As a result, bearings manufactured from this material offer high precision, smooth operation, high hardness, good strength, and long durability; however, they are expensive. 5. Silicon carbide is a newly synthesized type of inorganic non-metallic material. Its hardness is lower than that of diamond; it boasts good resistance to chemical corrosion, wear, and high temperatures, as well as high mechanical strength, excellent self-lubricating properties, resistance to high-temperature creep, a low coefficient of friction, high thermal conductivity, and a low coefficient of thermal expansion. It can be widely used in industries such as petroleum, metallurgy, chemicals, machinery, aerospace, and nuclear energy, and is commonly used as a material for friction pairs in sliding bearings and mechanical seals. Numerous tests have shown that silicon carbide is an excellent material for use in friction pairs at present, with pressureless sintered SiC and hot-pressed sintered SiC exhibiting the best properties.