Contents Foreword vii Preface xi Acknowledgements xvii List of Acronyms xix CHAPTER 1: INTRODUCTION 1 1.1 Defence Metallurgical Research Laboratory 1 1.2 Gas Turbine Engines 2 1.3 Superalloys 10 1.4 Brief Description of the Investment Casting Process 14 1.5 Overview of Work Done in DMRL 23 CHAPTER 2: SUPERALLOYS ? A NARRATIVE 27 2.1 Introduction 27 2.2 Physical Metallurgy 34 2.3 TCP Phases 42 2.4 Mechanical Properties 45 2.5 Creep 51 2.6 Solution Strengthening 52 2.7 Precipitation Hardening 53 2.8 Single Crystal Superalloys 53 CHAPTER 3: DEVELOPMENT OF INVESTMENT CASTING 61 3.1 Introduction 61 3.2 Shell Manufacture 63 3.3 Investment Casting 89 3.4 Directional Solidification of Turbine Components 115 3.5 Single Crystal Castings 150 vi 3.6 Post-casting Operations 156 3.7 Modelling and Simulation of the Casting Process 161 CHAPTER 4: DIE DESIGN AND FABRICATION 171 4.1 Introduction 171 4.2 Principles of Die Design 172 4.3 Design, Fabrication and Inspection of Dies 194 4.4 Engineering Model Parts 210 CHAPTER 5: CERAMIC CORES FOR HOLLOW TURBINE 213 COMPONENTS 5.1 Introduction 213 5.2 CIM Technique 215 5.3 Making Ceramic Cores 217 5.4 Leaching of Ceramic Cores from Castings 237 5.5 Technology Off-shoots 247 CHAPTER 6: SURFACE PROTECTION COATINGS 251 6.1 Introduction 251 6.2 Pack Cementation Process 252 6.3 Evaluation of Oxidation and Mechanical Properties 264 6.4 Failure Analysis of Pt-aluminide Coated Parts of Kaveri Engine 270 6.5 EBPVD Process for Application of Thermal Barrier Coating 277 CHAPTER 7: INDIGENISATION OF EQUIPMENT FACILITIES 291 7.1 Introduction 291 7.2 Machines for Ceramic Injection Moulding 291 7.3 Vacuum Furnaces for Investment Casting 304 7.4 Design of a Tool for Pin-pimples Removal 308 CHAPTER 8: OVERVIEW OF ACHIEVEMENTS 311 Appendix A: Thermodynamic Analysis of Brayton Cycle 315 Appendix B: Shrinkage of Parts in Directional Solidification 323 Appendix C: A Methodology for Identification of Defects in Cast 329 Components using Simulated Radiogram Index 335