What is sintering and what is it used for?

Description

High heat and pressure are used during sintering, also known as frittage, to generate a solid mass of material without melting it into a liquid. In addition to being utilised in the production of materials with high melting points, such as tungsten and molybdenum, this is also a naturally occurring occurrence in mineral and metal resources. Structural steel components, tungsten wiring, self-lubricating bearings, magnetic materials, electrical contacts, dental and medical items, cutting tools, and porous metals for filtration are all made via sintering.

Materials have an ideal sintering point, which is similar to their melting point. At this point, heat and pressure are sufficient to minimise the porous spaces between the material’s particles and compress loose material into a solid lump. Additionally, this contributes to the improvement of the material’s strength, integrity, translucency, and electrical and thermal conductivity.

It is possible to sinter most metals. The overall volume of the material may decrease during sintering as the density rises and the substance fills in gaps before metal atoms move along crystal boundaries and smooth out the pore walls as a result of surface tension. Surface contamination can be avoided by using pure metals sintered in a vacuum or in a chamber filled with protective gases.

Types Of Sintering

Sintering each tailored to specific materials and applications. Here are the main types of sintering (What Is Sintering?, n.d.-a):

1. Solid-State Sintering: The most common type, mainly used for metals and ceramics.

1. Plastic Sintering: Applied to polymers and plastics, often used in additive manufacturing or 3D printing.
2. Microwave Sintering: Microwave radiation is used to heat, reducing processing time and energy consumption.
3. Spark Plasma Sintering (SPS): It allows for high-density results, like nanomaterials.
4. Electro Sinter Forging: This combines electric current and mechanical pressure and is ideal for creating small, high-strength parts with precise tolerances.
5. Pressureless Sintering: Typically under a vacuum or inert gas atmosphere and is used for materials that don’t require added pressure for densification.
6. Liquid phase Sintering: One component of the material melts while others remain solid and are typically used in composite materials.

What are the advantages of sintering?

While the different methods and materials offer a range of benefits, there are a number of general advantages associated with sintering (What Is Sintering?, n.d.-b):

1. Purity: Because sintering is a simple production technique, it can retain high levels of purity and uniformity in the starting ingredients.
2. Repeatable: Keeping the grain size under control during input enables extremely repeatable processes.
3. No Binding Contact / Inclusions: Sintering prevents binding interaction between powder particles or inclusions, often known as “stringering,” unlike some melting procedures.
4. Uniform Porosity: Produce materials with a consistent, regulated porosity.
5. Nearly Net-Shaped Objects: Sintering can produce items that resemble nets.
6. High Strength Materials: Turbine blades and other strong things can be made using sintering.
7. High Mechanical Handling Strength: The mechanical strength for handling is enhanced during the sintering process.
8. Work with Difficult Materials: Sintering enables you to work with materials, like metals with extremely high melting temperatures, that cannot be used with other processes.

What are the disadvantages of sintering process?

The following disadvantages are associated with the sintering process.

• Sintering requires a large quantity of material.
• There is a higher initial capital cost for manufacturers for using the sintering method.
• Size of the sintering chamber is a limiting factor for what sizes of sintered material can be produced.

Conclusion

Sintering works through the diffusion of atoms across particle boundaries before fusing together into one piece under the influence of pressure and/or heat. While this process can occur naturally for mineral deposits, it is also widely used by a range of industries to manufacture items from materials including ceramics, metals and plastics.

Sintering occurs at heats below the melting point of the materials, making it useful for creating items from metals that have high melting points.

There are a range of different techniques depending on factors such as the use of electrical currents, pressure and heat sources as well as the actual materials being sintered.

Reference

What is Sintering? A Complete Guide to the Process and Uses. (n.d.-a). Retrieved January 30, 2025, from https://www.hlc-metalparts.com/news/what-is-sintering-81346837.html

What is Sintering? (A Definitive Guide). (n.d.-b). Retrieved January 30, 2025, from https://www.twi-global.com/technical-knowledge/faqs/what-is-sintering.aspx