A PRESENTATION ON SINTERING

PRESENTED BY:- Anshul Gautampurkar

Class- S.Y. (P.P.E.)

Roll no.- T2704

Subject:- Material Science

INTRODUCTION

SINTERING = SINTER + ING.“Sinter” is a German word derived from the english word “cinder”.“Cinder” means partly burnt coal or wood.Hence, sintering is something related to powder ,as, partly burnt coal or wood is in powderous form.

What sintering actually is??

Sintering is a method used to create objects from powders. And the study of sintering and of powders related processes is known as powder metallurgy.A simple example of sintering can be observed when ice cubes in a glass of water adhere or stick firmly to each other. PRINCIPLE:-Sintering is based on atomic diffusion.

HOW IS SINTERING DONE??

Sintering is based on atomic diffusion. And diffusion occurs in any material above absolute zero but it occurs much faster at higher temperatures. In most sintering processes the powdered material is held in a mold(form for shaping molten or plastic material) and then heated to a temperature below melting point. The atoms in the powder particles diffuse across the boundary of the particles, fusing the particles together and creating one solid piece.

WHERE IS SINTERING USED??

Because the sintering temperature does not have to reach the melting point of the material sintering is often chosen as the shaping process for materials with extremely high melting points such as tungsten and molybdenum. Sintering is traditionally used for manufacturing ceramic objects but finds applications in almost all fields of industry.

General sinteringSintering ids effective when the process reduces the porosity and enhances the properties such as strength, electrical conductivity, translucency and thermal conductivity, yet, in other cases it may be useful to increase its strength but keep its gas absorbency constant as in filters or catalysts. During the firing process atomic diffusion drives powder surface elimination in different stages, starting from the formation of necks between powders to final elimination of small pores at the end of the process.

Sintering mechanismsSintering occurs by diffusion of atoms through the microstructure. This diffusion is caused by a gradient of chemical potential –atoms move from an area of higher chemical potential to an area of lower chemical potential.

diffusion mechanism

Low chemical potential

High chemical potential

The different paths the atoms take to get from one spot to another are the sintering mechanisms. The six commonSintering mechanisms are:-

Surface diffusion

Vapor transport

Lattice diffusion from surfaceLattice diffusion from grain boundary

Grain boundary diffusion

Plastic deformation

MECHANISMS IN DETAIL-

Surface diffusion- Diffusion of atoms along the surface of a particle.

Vapor transport- Evaporation of atoms which condense on a different surface.

Lattice diffusion from surface- Atoms from surface diffuse through lattice.

Lattice diffusion from grain boundary- Atoms from grain boundary diffuses through lattice.

Grain boundary diffusion- Atoms diffuse along grain boundary.

Plastic deformation- Dislocation motion causes flow of matter.

CATEGORIZATION OF SINTERING:-

Sintering can be categorized into 6 broad categories:-S

inte

rin

gCeramic sintering

Sintering of metallic powders

Plastics sintering

Liquid phase sintering

Electric current assisted sintering

Spark plasma sintering

Pressure less sintering

PLASTIC SINTERING:- Plastic materials are formed by sintering

for applications that require materials of specific porosity.

Sintered plastic porous components are used in filtration and to control fluid and gas flows.

Sintered plastics are used in applications requiring wicking properties, such as marking pen nibs.

Sintered ultra high molecular weight polyethylene materials are used as ski and snowboard base materials.

Almost any substance can be obtained in powder form either through chemical, mechanical or physical processes so basically any material can be obtained through sintering. When pure elements are sintered the leftover powder is still pure, so it can be recycled.With this my presentation on sintering comes to an end.

Thank you

Have a nice day