Sintering

General Sintering

• Sintering is a process of compacting and forming a solid mass of material by pressure or heat without melting it.
• It is used in manufacturing processes for metals, ceramics, plastics, and other materials.
• Sintering can occur at temperatures below the melting point of the material.
• It is often chosen for materials with high melting points, such as tungsten and molybdenum.
• The study of sintering in metallurgical powder-related processes is known as powder metallurgy.

Ceramic Sintering

• Sintering is part of the firing process used in the manufacture of pottery and other ceramic objects.
• It is one of the main mechanisms behind the strength and stability of ceramics.
• Sintered ceramic objects are made from substances such as glass, alumina, zirconia, silica, and ferric oxide.
• Sintering begins when sufficient temperatures have been reached to mobilize the active elements in the ceramic material.
• Industrial procedures for ceramic sintering include mixing, spray-drying, molding, and high-temperature sintering.

Sintering of Metallic Powders

• Most metals can be sintered, especially pure metals produced in a vacuum.
• Sintering can occur under atmospheric pressure.
• It is a common process for shaping metallic powders into solid parts.
• Sintering of metallic powders can enhance properties such as strength and conductivity.
• The sintering process for metallic powders is widely used in industries such as automotive and aerospace.

Densification in Sintering

• Sintering is considered successful when it reduces porosity and enhances properties such as strength and conductivity.
• Atomic diffusion drives powder surface elimination during the firing process.
• The change in free energy from the decrease in surface area and lowering of surface free energy is the driving force for densification.
• The ratio of bond area to particle size influences properties such as strength and electrical conductivity.
• Temperature and initial grain size are controlled to yield the desired bond area during sintering.

Factors Affecting Sintering

• Control of temperature is crucial in the sintering process.
• Grain-boundary diffusion and volume diffusion rely heavily on temperature.
• Particle size, particle distribution, material composition, and sintering environment also affect the sintering process.
• The size and curvature of particles affect material transfer during sintering.
• Pore elimination is fastest in samples with many pores of uniform size.

Sintering Data Sources