Bearing bush material of the hottest unlubricated

The bearing materials of unlubricated bearings

the bearing materials of unlubricated bearings mainly include polymers, carbon graphite and special ceramics

(1) polymer

polymer is also called plastic, and the plastic used as mechanical engineering materials is called engineering plastic. It is an organic polymer material with synthetic resin as the main component, and also contains various plasticizers, stabilizers, antioxidants, antistatic agents, flame retardants, curing agents, reinforcements and fillers

there are many kinds of polymers, which can be divided into thermoplastic and thermosetting according to their characteristics. According to 3 rhombic materials

commonly used thermoplastic polymers include polyamide, polyacetal, polyethylene, polytetrafluoroethylene, polypropylene, polyurethane, etc. They are organic polymer compounds with linear or branched chain structure, which can be repeatedly softened by heating and hardened by cooling. Thermoplastics can be molded by injection molding, extrusion, blow molding, calendering and other processes

thermosetting polymers are mainly phenolic resin, epoxy resin, etc. They are cured by adding catalyst or curing agent in the processing process. Once the curing is completed, it will become a solid material that will never melt. Thermosetting polymers can be molded by pressing, laminating, casting and other methods

plastic is commonly used to make friction pair parts such as bearings, guide rails, piston rings, etc., such as water pump bearings, rolling mill bearings, stern bearings, etc., especially non lubricated bearings made of plastic. PTFE sheets are stamped into lip seals, bearing shells, piston rings and gaskets, which have been successfully applied to belt conveyors, typewriters, sewing machines, phonographs, water pumps, textile machinery, agricultural machinery and other equipment

polymers have the characteristics of light weight, insulation, antifriction, wear resistance, self lubrication, corrosion resistance, simple molding process and high production efficiency. Compared with metal materials, their tribological properties are sensitive to ambient temperature and humidity, significantly related to viscoelasticity, low mechanical strength, small elastic modulus, and poor adsorption on lubricating oil

2. Carbon graphite material

graphite is a kind of non-metallic material composed of carbon elements. It is one of the three isomers of carbon element, belonging to hexagonal system. Each layer is composed of hexagonal rings, and the layers are parallel to each other, showing an orderly overlapping crystal structure

graphite is divided into natural graphite and artificial graphite according to its source. Artificial graphite is made of carbon materials by graphitizing at a high temperature above 2500 ℃

carbon graphite generally has good conductivity, heat resistance, wear resistance, self lubrication, high temperature stability, strong chemical corrosion resistance, higher thermal conductivity than polymers, and smaller linear expansion coefficient. The friction coefficient and wear rate with chromium plated surface are very low under atmospheric and room temperature conditions. However, the lubricity will be lost when the humidity is very low. Coating with wear-resistant coating can improve the wear resistance of carbon graphite

graphite can not only be used as a solid lubricant, but also can be added to resins, metals, ceramics and other materials to increase the antifriction of these materials. It can also be directly used as a friction pair material, such as bearings in oil repellent places such as papermaking, wood processing, textile, food and so on, high-temperature sliding bearings, sealing rings, piston rings, exchange servomotors, drive the rotating blade of double ball screw through synchronous toothed belt reducer, etc

the "class" symbol of carbon graphite materials for mechanical engineering is m, which has four series: carbon graphite materials, electrochemical graphite materials, resin carbon composites and metal graphite materials

3. Ceramic material

ceramics is a non-metallic material composed of numerous inorganic non-metallic small crystals and glass phases, which is made of inorganic non-metallic natural minerals or man-made compounds through crushing, forming and high-temperature sintering. Traditional ceramics are made from inorganic non-metallic natural minerals, such as clay, feldspar, quartz, etc; Special ceramics are made from man-made compounds. Ceramics used in mechanical engineering are generally special ceramics made of artificial compounds such as alumina, magnesium oxide, zirconia, lead oxide, titanium oxide, silicon carbide, boron carbide, silicon nitride, boron nitride, etc

the properties of ceramics are largely determined by their microstructure, including grain size and distribution, composition and content of glass phase, nature, content and distribution of impurities. The microstructure is determined by the expected borrowing and replenishment market. At present, the raw materials, composition and manufacturing process have not been widely revealed. The common characteristics of ceramics are high hardness and compressive strength, high temperature resistance, wear resistance, oxidation resistance, good corrosion resistance, brittleness, impact resistance and no ductility

ceramics are relatively new bearing materials for non lubricated bearings, especially SiC and Si3N4. Their strength, heat resistance, tooling cost and labor cost are also significantly reduced. They have good corrosion resistance and tribological properties. (end)