hot isostatic pressing

HOT ISOSTATIC PRESSINGMuhammed Labeeb

CONTENTS

▪ INTRODUCTION

▪ NEED

▪ PROCESS

▪ EQUIPMENTS

▪ ADVANTAGES AND LIMITATION

▪ REFERENCE

INTRODUCTION

▪ Hot isostatic pressing (HIP) is a powder metallurgy technique

▪ HIP is used to reduce the porosity of metals and increase the density of many ceramic materials

▪ This improves the material's mechanical properties and workability

▪ Process uses the combination of high temperatures and high pressures to densify engineering ceramics and hard metals

▪ Pressures of up to 207 MPa (30,000 psi) may be used with the temperature of operation being as high as 2000°C (3,632°F)

▪ Typically, an inert gas (Argon or Nitrogen) is used within the pressure vessel to ensure that pressure is applied uniformly from all sides (Isostatic Pressure)

NEED FOR HIP

Influence of porosity (density) on impact strength and tensile strength of P/M materials.

The effect of porosity on fatique strength

NEED FOR HIP

▪ Permissible porosity depends on application field

▪ Higher loads call for higher density

▪ Conventional P/M technology (press- and -sinter technology) in most cases doesn`t enable to achieve full density.

▪ Hot consolidation processes (hot pressing, HIP, extrusion etc) enable to produce full-density or near full-density or near full-density powder materials/products

▪ The primary use of HIP is to increase the density of the material and increase the strength and reliability of the components

HIP

▪ In hot isostatic pressing (HIP), the container is made of a high-melting-point sheet metal and the pressurizing medium is a high-temperature inert gas

▪ Originally Helium and now Argon is used as pressurizing medium

▪ Total pressure = pressure due to heating + applied pressure(dependent on load)

▪ Pressure vessel requires high fatigue and creep resistance.

▪ Should be immune to heating, dwell and cooling periods, coolant/failure of cooling system.

PROCESS

HIP

THERMOCOUPLES

PRESSURE SYSTEM

HEATING ELEMENTSFURNACE

PRESSURE VESSEL

HIPEQUIPMENT

APPLICATIONS

▪ Silicon Nitride Ball Bearings

▪ Body Armour

▪ Zirconia and Alumina Dental implants

▪ Multi-Layer Capacitors

▪ Downhole Oilfield Components

▪ Sputtering Targets

ADVANTAGES

▪ Materials/products of higher performance

▪ The HIP is near-net shape process

▪ Lower unit costs of large parts and production volumes of small-weight parts

▪ Produces fully dense compacts of uniform grain structure and density

▪ Decreased scatter and recovery of defective parts.

▪ Improved ductility and impact strength.

▪ Fine grains

LIMITATIONS

▪ Materials/products of higher performance

▪ The HIP is near-net shape process

▪ Lower unit costs of large parts and production volumes of small-weight parts

▪ Produces fully dense compacts of uniform grain structure and density

REFERENCE

▪ http://en.wikipedia.org/wiki/Hot_isostatic_pressing

▪ http://www.azom.com/article.aspx?ArticleID=5769