1. Friction compatibility
When the shaft diameter of plain bearing is in direct contact with the bearing bush, it can prevent adhesion and form boundary lubrication. The material factors that affect the friction compatibility of friction pair are as follows
(1) The degree of difficulty in metallurgical composition of alloy.
(2) The affinity between the material and lubricant.
(3) The friction coefficient of the paired material in the unlubricated state.
(4) The microstructure of the material.
(5) The thermal conductivity of the material.
(6) The surface energy of the material and the characteristics of the oxide film.
2. Embeddedness
The ability of flat bearing materials to prevent scratching and / or abrasive wear by allowing foreign hard particles in the lubricant to be clamped in. For metal materials, low hardness and low modulus of elasticity lead to good embeddability, while for non-metal materials, such as carbon graphite, low modulus of elasticity leads to poor embeddability. Sliding bearing usually uses soft material and hard material to form friction amplitude, and generally uses soft material as bearing bush.
3. Running in
In the process of running in, the machining error, coaxiality error and surface roughness parameter value of shaft diameter and bearing bush can be reduced to make the contact uniform, so as to reduce the friction and wear rate.
4. Friction compliance
The material relies on the elastic-plastic deformation of the surface layer to compensate for the poor initial fit of the sliding friction surface and the deflection of the shaft. The material with low elastic modulus has better compliance.
5. Wear resistance
The ability of materials to resist wear. Wear resistance is expressed by the reciprocal of wear rate, wear degree and wear amount under the specified wear condition.
6. Fatigue resistance
The ability of material to resist fatigue failure under cyclic loading. At the service temperature, the strength, hardness, impact strength and microstructure uniformity of bearing material are very important for anti fatigue. Materials with good running in and embedment usually have poor fatigue resistance.
7. Corrosion resistance
The ability of materials to resist corrosion. When lubricating oil is used in the atmosphere, it will gradually oxidize and produce acid substances. Moreover, most lubricating oils also contain extreme pressure additives, which will corrode the bearing materials. Therefore, bearing materials need to have corrosion resistance.
8. Cavitation resistance
When the bubble in the liquid breaks near the surface of the solid when the solid moves relative to the liquid, it will produce local impact high pressure or local high temperature, which will lead to cavitation wear. The ability of a material to resist cavitation wear is called cavitation resistance. Generally, copper lead alloy, tin based bearing alloy and Al Zn Si alloy have better cavitation resistance.
9. Compressive strength
The ability to withstand unidirectional loads without crushing or dimensional changes. |
