Introduction
Powder metallurgy is a technology that is used in the manufacturing of machine components and other substances by compression and heating treatment. In the powder metallurgy process, a mixture of metal powders is first compressed into a shape, and then the shape is heated up to the melting point to form the desired object. In this process, tribological properties (friction, wear, and lubrication) are important factors that affect the final quality of the product. In order to improve tribological properties, different types of additives such as solid lubricants, carburizing agents and friction modifiers are incorporated into the metal powder mixture. In this paper, we will look at how the use of friction reducing materials and additives can lead to improved tribological properties of metal powder metallurgical components.
Friction Reducing Materials
Friction reducing materials are used to reduce friction by coating the metal surfaces of metal powder metallurgical components. These materials act as a barrier between the moving parts which results in less wear and tear. Different types of friction reducing materials can be used such as lubricants, oils, greases, and dry lubricants. The most common materials used in powder metallurgy are lubricants, oils and greases.
Lubricants are used to reduce friction and prevent wear. They are usually in liquid form and can range from synthetic oils to animal and vegetable oils. Depending on the application, different types of lubricants can be used. Some of the most commonly used lubricants are mineral oils, polyalphaolefins (PAOs), polyalkylene glycols (PAGs) and synthetic esters.
Oils are used to reduce friction and protect the metal surfaces from corrosion. They generally have a higher viscosity than lubricants and are usually used for lubricating the components which have tight clearances. Commonly used oils include mineral oils, vegetable oils and synthetic oils.
Greases are usually used for applications which require higher load bearing and wear protection. The most common type of grease used in powder metallurgy is polyalkyleneglycol (PAG). It is low in cost and provides excellent lubrication and corrosion protection.
Additives
Additives are also used to improve the tribological properties of powder metallurgical components. They are typically incorporated into the metal powder mixture to protect the components from wear and corrosion. Common additives used in powder metallurgy include carburizing agents, solid lubricants, and friction modifiers.
Carburizing agents are used to increase the hardness and wear resistance of the components. They are typically added to the metal powder mixture in the form of a liquid or solid and include compounds such as cyanide, hydrogen cyanide, and halides.
Solid lubricants are made from ceramic or metallic powders and are used to reduce friction and serve as a barrier between the sliding surfaces. Commonly used solid lubricants are graphite, molybdenum disulfide, tungsten disulfide, and boron nitride.
Friction modifiers are used to decrease the coefficient of friction between the components. They are usually added to the metal powder mixture in the form of liquids or solids and include materials such as molybdenum disulfide, graphite, and tungsten disulfide.
Conclusion
In conclusion, the use of friction reducing materials and additives can lead to improved tribological properties of metal powder metallurgical components. These materials and additives act as lubricants, protect the surfaces from corrosion, increase wear resistance and decrease friction. By using these materials, components can have improved service life and better performance.
