Thermal Spraying for Power Generation Components

Transcription

1 Klaus Erich Schneider, Vladimir Belashchenko, Marian Dratwinski, Stephan Siegmann, Alexander Zagorski Thermal Spraying for Power Generation Components WILEY- VCH WILEY-VCH Verlag GmbH & Co. KGaA

2 Contents Preface V The Authors of this Book VII 1 Introduction Requirements for Materials and Coatings in Powcrplants 1.2 Examples of Coatings in Gas Turbines Definition of Thermal Spraying (THSP) Thermal-Spraying Systems Coatings for Power-Generation Components The Complete Manufacturing and Coating Process Coating-Process Development Tasks for "Target" Readers 35 2 Practica I Experience Today Coating Processes J7 2.2 Basics of Thermal Spraying Feedstock Wire Powder Powder Types Powder-Production Processes and Morphologies Powder Characterization Powders for Power-Generation Applications Thermal-Spraying Equipment Example of a Low-Pressure Plasma-Coating System Flame and Are Spray Torches HVOF Process Comparison of HVOF Fuels A Brief Overview of the Major Existing HVOF Systems Possible [mprovements of HVOF Systems Plasma Process A Brief Overview of Plasma Torches 58 Thermal Spraying for Power Generation Components '{. E. Schneider, V. Bdashchfriko, M, Dratwinski, S. Siegrmnn, A. Zagorski Copyright 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN:

3 X Contents Possible Improvements of Plasma Systems Work Flow and Important Coating Hardware Powder Preparation and Powder-Dclivery System Powder Preparation Powder Delivery and Injection System Powder Injection and Plasma/Hot Gas Jet Injector Plugging and "Spitting" Powder Buildup at the Front Nozzle Wall Cooling System Power-Supply System Gas Supply and Distribution System Manipulation Systems Fixtures and Masking Examples of Coated Power-Generation Components Production Experience Surfate Preparation Internal Plasma and Transferred Are Process and Systems Tbe Programming of fhe Coating Process Finishing Repair of Turbine Parts Coating Removal, Stripping Restoration of the Base Materials Refurbisbing, Recoating Commercial General Surfa.ee Preparation Coating Equipment Finishing Quality and Process Capability Quality Assurance Sources of Process Variations Special Causesof Coating-Process Variation Stochastic Nature of a Spray Process Are and Jet Pulsations Powder-Size Distribution Powder Injection Powder Sbape Particle Bonding Gun and Component Motion and Positioning HO Drifting S tability of the Quality Control Process Capability and Stable Process Definition of Process Capability 115

4 3.3.2 Definition ofa Stahle Coating Process Operational Window 1J What Process Capability is Required? Additional Factors that Affect the Process Capability Case Study: Achievable Process Capability Part Complexity Mutual Position of the Gun and Component Fixtures Powder Quality Torch Pulsations and Drifting lnstability of the Quality-Control Process Surface Preparation and the Part Temperature Conditions of the Powder-Injection System Process Capability Maintenance Theory and Physical Trends Coating Formation from Separate Particles: Particle Impact, Spreading and Bonding Physics of Plasma Torches Plasma Properties Gas Dynamics of Plasma Torch Energy Balance of the Plasma Gun Major Trends Variation of the Gun Power; the Gas Flow Rates and Composition Unchanged Variation of the Plasma Composition at the Same Specific Plasma Enthalpy Variation of the Plasma Flow Rate at Unchanged Gun Power and Gas Composition Effect of Nozzle Diameter Plasma Swirl Structure of Plasma Jets APS Jet S tructure oflppsjet Particles in Plasma Particles at APS Particle at LPPS Particle Acceleration and Heating in the LPPS Free Jet Particle Acceleration and Heating Inside the Nozzle Spray Footprint (Spray Pattern) Influenceof Particles on Plasma Flow Substrate Surface Temperature Formation of the Coating Layer Useof Different Plasma Gases Some Distinguishing Features ofhvof Physics 169

5 XII Contents 5 Offline Simulation of a Thermal-Spray Process Simulation in Production Physical Background of Simulation Package Viscoplasticity Model of a Splat and Particle Bonding Thermodynamic and Transport Properties of Argon/Hydrogen Mixtures Modeling of the Plasma Gun Modeling of the Plasma Jets APS Jet LPPSJet Acceleration and Heating of Parti des in Plasma Surface Thermal Conditions Spray Pattern Calibration of the Bonding Model and Sensitivity of a Spray Pattern to the Process Parameters, Spray Angle and Bonding Model Coating Porosity and Roughness Modeling of Turbine Blades Coating Thickness Optimization and Stochastic Modeling Tools Simulation ofhvof Process Use of Offline Simulation in Coating Development Application Areas of Modeling in the Coating Process Coating Definition and Design for Coating Coating-Process Development Part Development Physical Modeling and Offline Simulation as Process-Diagnostic Tools Simulation as a Numerical Experiment When the Offline Simulation Should Be Used Standards and Training Standards, Codes Introduction to Standards Quality Requirements for Thermally Sprayed Structures and Coating Shops QuaKfication and Education of Spraying Personnel Special Case: Spraying for Power-Generation Components Coating-Process Development Coating Production Genera] Requirements for Coating-Shop Personnel Monitoring, Shopfloor Experience and Manufacturing Process Development Monitoring, Sensing Introduction of Monitoring Particle-Monitoring Devices 217

6 Contents XIII Influence of Spray Parameters on Particle Speed and Tcmperature Influence of Particle Velocity and Tempcrature on Microstructure How to Use Monitoring for Process Control Monitoring, Sensing from a Job Shop Point of View Vision for Future Coating Control and Monitoring Manufacturing Coating Development Coating Development Process Coating Definition and Coating Specification; Design for Coating Process Development Powder Selection Torch Parameters Spray Pattern and Standoff Distance Coating Mono-Layer; Powder Feed Rate and Traverse Gun Speed Spray Trials and Coating Qualification Sensitivity Checks Part Development Coating Program Process Qualification and Preserial Release Serial Release Outlook, Summary Thermal Spray Torches Future Offline Programming and Monitoring in Process Development and Production 244 References 245 Subject Index 261