What Is Sintered Metal ?

Sintered metal is a type of metal material made through sintering process. Below is a detailed introduction to sintering technology and the definition, characteristics, raw materials, and applications of sintered metals .

1.Agglomeration process
Sintering is a process of pressing and forming solid materials, in which heat and/or pressure is applied to the material during the manufacturing process, but the heating temperature is lower than the melting point of the material. During this process, atoms in the material diffuse across the boundaries of particles, and the particles fuse to form a solid entity. Due to the fact that the sintering temperature has not reached the melting point of the material, sintering is usually chosen as the molding method for materials with extremely high melting points.

2.Definition of sintered metal
① From a process perspective
Sintered metal is a material made by pressing and sintering metal powder or wire mesh. For example, sintered metal wire mesh is made from metal powder or metal wire mesh as raw materials, which are pressed and sintered to form a porous body with certain permeability and mechanical strength.
② From a structural perspective
Taking metal fiber sintered felt as an example, it is made by compacting and sintering very fine stainless steel fibers in a three-dimensional maze like manner. The metal fibers used in the sintering process have a high ratio of length to diameter, which allows countless contacts of the fibers to be spot welded together, thus producing a filter material without fiber shedding.

3.Characteristics of sintered metals
① Porosity: It has a certain degree of permeability, with many pores inside, which makes it widely used in fields such as filtration. For example, sintered metal wire mesh has a porous structure that can be used for filtration.
② Mechanical strength: After sintering, the material has a certain mechanical strength that can meet the mechanical performance requirements of different application scenarios.
③ Adjustable performance: By adjusting sintering process parameters such as temperature, pressure, time, etc., the grain size, pore size, and shape and distribution of grain boundaries in the microstructure of sintered metals can be controlled, thereby affecting their performance.

4.Raw materials for the production of sintered metals
① Metal powder
• Overview: The basic raw material for sintered metals is usually metal powder, which can be a single metal powder or a mixture of metal powder and non-metal powder. Powder metallurgy is the process technology of producing metal powder or using metal powder (or a mixture of metal powder and non-metal powder) as raw materials, forming and sintering, and manufacturing metal materials, composite materials, and various types of products.
• Advantages: For some special alloys, such as those with high melting points, large differences in melting points of constituent elements, poor castability, or materials with high added value that cannot be used by melting and casting processes, powder metallurgy sintering has the advantages of low process temperature, high sintering density, and short sintering time.
② Packaging materials
Function: The material embedded in the pre sintering or sintering process to separate and protect the compact is called packaging material. It helps to ensure the quality and performance of the compact during the sintering process.
③ Graphite products
• Graphite mold
Characteristics: Graphite molds are key tools for metal powder compression molding, with high thermal conductivity. Their thermal conductivity is 3-5 times that of ordinary steel, which can quickly transfer heat, ensure uniform mold temperature, and reduce internal stress in sintered parts; High temperature resistance, able to withstand temperatures above 2000 ℃ in an inert atmosphere, suitable for sintering high melting point metals such as tungsten and molybdenum; Easy to process, complex cavities can be made through CNC machining to meet the precision forming requirements of microelectronic components.
• Graphite crucible
Performance advantages: In the pre alloying or infiltration process of metal sintering, graphite crucibles are used to melt metal raw materials or intermediate alloys. It has strong resistance to the erosion of molten metals such as copper, silver, and nickel based high-temperature alloys, and its service life is 2-3 times that of traditional ceramic crucibles

5.Application of sintered metals
① Electronic and electrical equipment
Sintered metal soft magnetic materials have important applications in electronic and electrical equipment. This type of material has high magnetic permeability and low hysteresis loss, which can improve the performance and efficiency of equipment. For example, in motors, sintered metal soft magnetic materials can be applied to the stator and rotor parts of the motor to improve its speed and efficiency. In transformers, this material can be applied to the iron core of the transformer to improve transmission efficiency and reduce losses.
②  Automotive industry
In the automotive industry, sintered metals are widely used to manufacture various components such as bearings, gears, and filters. These components typically require good wear resistance, corrosion resistance, and high strength, and sintered metals can meet these requirements by adjusting the composition of the powder and sintering process.
③  Aerospace
The aerospace industry has extremely strict requirements for materials, requiring them to have characteristics such as lightweight, high strength, and high temperature resistance. Sintered metals can meet these requirements and therefore have a wide range of applications in the aerospace industry. For example, graphite heaters (such as rods and tubes) are the core components of vacuum sintering furnaces, responsible for providing a uniform thermal field. They can operate up to 2800 ℃ in vacuum or inert atmosphere, much higher than the limit of metal heating elements (such as molybdenum, which has a temperature of 1600 ℃). The isostatic pressure graphite heater developed by Chengdu Charcoal Materials has a diameter of 1.5 meters and supports large-scale sintering of core materials for fourth generation nuclear reactors, filling the domestic gap.
④ Medical devices
In the field of medical devices, sintered metals are also widely used. Due to its ability to achieve high-precision manufacturing, sintered metals are highly suitable for manufacturing precision devices such as micro connectors and medical implants. In addition, high-purity graphite ensures that semiconductor packaging materials are pollution-free, with a yield rate of over 99.5%, which is crucial for the reliability and safety of medical equipment.
⑤ Energy sector
In the field of energy, sintered metals are used to manufacture various high-performance energy conversion and storage devices. For example, sintered metal soft magnetic materials can be applied in energy conversion equipment to improve the efficiency and performance of the equipment. Meanwhile, sintered metals can also be used to manufacture electrode materials for batteries, improving their energy density and cycle life.