Czerwinski Magnesium Injection Molding

1. Auflage 2007
ISBN: 978-0-387-72528-4
Verlag: Springer-Verlag
Format: PDF
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 592 Seiten

The continuous quest for weight reduction, especially in ground and air transportation, has catalyzed the de velopment of light metals and alloys. In this search, particular attention is being paid to magnesium, used at present in a diversity of applications, each one exploring a specific range of unique properties. As a result, the magnesium consumption by many important market sectors is growing at an impressive rate exceeding 10% per year. In parallel with the alloy development the search continues for new techniques of converting magnesium into useful products in a safe and effective manner. Magnesium injection molding, commercialized in recent years, represents a modern technology that is clean and safe for workers as well as friendly for an environment. Extensive research, conducted at both the industrial and university levels, indicates that the technique exceeded its initial expectations. While combining key features of a number of processing techniques, magnesium injection molding is emerging as a universal technology, capable of implementing many conventional and novel processing routes. The routes are based on both the semisolid slurry and fully molten alloy with tightly controlled temperature. Despite well-advanced practice, the critical breakthrough is still hindered by slow progress in understanding key mechanisms, controlling the process at stages of slurry preparation and component forming.

Autoren/Hrsg.

Czerwinski, Frank

Inhaltsverzeichnis

1;Preface;6
2;Biography;8
3;Contents;9
4;Magnesium and Its Alloys;21
4.1;1.1 Introduction;21
4.2;1.2 Market Development;21
4.3;1.3 Production Techniques of Pure Metal;29
4.4;1.4 Fundamentals of Alloying;38
4.5;1.5 Alloys;49
4.6;1.6 Selected Properties of Alloys;60
4.7;1.7 Processing Techniques;72
4.8;1.8 Heat Treatment;81
4.9;1.9 Surface Protection;85
4.10;1.10 Application Markets;93
4.11;1.11 Summary;96
4.12;References;96
5;Semisolid Processing—Origin of Magnesium Molding;100
5.1;2.1 Introduction;100
5.2;2.2 Origin of the Concept ;100
5.3;2.3 Rheological Behavior of Semisolid Slurries ;102
5.4;2.4 Viscosity Measurements of Metallic Slurries;115
5.5;2.5 Rheological Measurements for Semisolid Magnesium Alloys;122
5.6;2.6 Techniques of Generating Globular Structures;126
5.7;2.7 Benefits of Semisolid Processing;134
5.8;2.8 Suitability Criteria of Alloys for Semisolid Processing;138
5.9;2.9 Industrial Implementations of Major Semisolid Concepts;143
5.10;2.10 Origin and Progress of Magnesium Molding;149
5.11;2.11 Present Applications and Future Opportunities for Magnesium Molding;154
5.12;2.12 Summary;163
5.13;References;164
6;Basic and Auxiliary Hardware;167
6.1;3.1 Introduction;167
6.2;3.2 Machine;167
6.3;3.3 Slurry Distribution Systems ;189
6.4;3.4 Mold ;192
6.5;3.5 Summary;198
6.6;References;198
7;Thermal and Corrosive Aspects of Processing Molten Magnesium;199
7.1;4.1 Introduction;199
7.2;4.2 High Temperature Effect of Molten Magnesium Alloys on Other Materials;200
7.3;4.3 Corrosive Behavior of Molten Magnesium Alloys;217
7.4;4.4 Summary;230
7.5;References;232
8;Process Theory and Practice;233
8.1;5.1 Introduction;233
8.2;5.2 Key Processing Parameters;233
8.3;5.3 Functions of the Injection Screw;241
8.4;5.4 Function of the Non-Return Valve;256
8.5;5.5 Nozzle Plug—Principles of Thermal Gating;260
8.6;5.6 Mold Processing;269
8.7;5.7 Common Defects;282
8.8;5.8 Product Quality Control;295
8.9;5.9 Summary;300
8.10;References;301
9;Feedstock Selection;303
9.1;6.1 Introduction;303
9.2;6.2 Techniques of Particulates Manufacturing;303
9.3;6.3 Characterization of Particulates Manufactured by Mechanical Fragmentation ;308
9.4;6.4 Characterization of Rapidly Solidified Granules;315
9.5;6.5 External Characteristics Affecting Injection Molding Applications;326
9.6;6.6 Global Manufacturing Market of Magnesium Particulates;328
9.7;6.7 Summary;330
9.8;References;330
10;Oxidation Behavior of the Feedstock;332
10.1;7.1 Introduction;332
10.2;7.2 Oxidation Kinetics;332
10.3;7.3 Oxidation Surfaces;336
10.4;7.4 Oxide Growth Morphologies ;337
10.5;7.5 Internal Structure of Oxide Layers;341
10.6;7.6 Oxide Phase Composition;343
10.7;7.7 Influence of Chemical Composition on Magnesium Oxidation;347
10.8;7.8 Evaporation Characteristics;349
10.9;7.9 Oxidation Mechanism;351
10.10;7.10 Ignition Behavior;355
10.11;7.11 Alloy Protection Against Oxidation and Ignition;356
10.12;7.12 Implications for Injection Molding Practice;363
10.13;7.13 Examples of Alloy Degradation from Injection Molding Practice;364
10.14;7.14 Summary;369
10.15;References;369
11;Melting Behavior of the Feedstock;371
11.1;8.1 Introduction;371
11.2;8.2 Factors Affecting Feedstock’s Thermal Instability;371
11.3;8.3 Solid-State Transformation During Heating;380
11.4;8.4 Microstructure Evolution During Feedstock Melting;390
11.5;8.5 Melting of As-Cast Ingot;408
11.6;8.6 Phenomena During Heating of Rapidly Solidified Granules;410
11.7;8.7 Microstructure Correlation Between the Solid and Semisolid State;415
11.8;8.8 Summary;419
11.9;References;420
12;Alloy Transformations During Molding;422
12.1;9.1 Introduction;422
12.2;9.2 Factors Controlling Microstructure Evolution;422
12.3;9.3 Solid-State Transformations During Initial Conveyance;424
12.4;9.4 Semisolid-State Transformations Within the Machine Barrel;427
12.5;9.5 Transformations Associated with the Seal Plug;435
12.6;9.6 Theories of the Formation of Globular Structures During Melting and Solidification;440
12.7;9.7 Evolution of the Primary Solid Phase During Molding;444
12.8;9.8 Engineering Microstructure for Commercial Applications;451
12.9;9.9 Summary;454
12.10;References;454
13;Microstructure–Property Relationship for Molded Alloys;456
13.1;10.1 Introduction;456
13.2;10.2 Parameters Characterizing Thixotropic Structures After Solidification;456
13.3;10.3 General Constituents of Thixotropic Microstructures of Magnesium Alloys;462
13.4;10.4 Internal Structure of the Primary Solid and Matrix ;467
13.5;10.5 Tensile Properties;471
13.6;10.6 Decohesion Characteristics;472
13.7;10.7 Structure–Property Correlation;477
13.8;10.8 Attempts at a Quantitative Description of the Structure– Property Relationship;478
13.9;10.9 Structure–Property Correlation for Magnesium Alloys, Processed with Other Semisolid Techniques;480
13.10;10.10 Modification of Mechanical Properties by the Post- Molding Heat Treatment;481
13.11;10.11 Summary;481
13.12;References;482
14;Semisolid Extrusion Molding;484
14.1;11.1 Introduction;484
14.2;11.2 General Features of SSEM;484
14.3;11.3 Mold Filling Characteristics and Part Integrity ;486
14.4;11.4 Structural Transformations During Molding and As- Solidified Structure;491
14.5;11.5 Characterization of Primary Solid;496
14.6;11.6 Application Areas for SSEM;499
14.7;11.7 Summary;500
14.8;References;500
15;Near-Liquidus Molding;501
15.1;12.1 Introduction;501
15.2;12.2 Growth of Globular Structures by Nucleation;501
15.3;12.3 The NLM Concept and Its Experimental Implementation;507
15.4;12.4 Microstructure After NLM;508
15.5;12.5 Tensile Properties;518
15.6;12.6 Structure-Property Correlation After NLM;519
15.7;12.7 Application Areas of NLM;522
15.8;12.8 Summary;524
15.9;References;524
16;Alloy and Composite Generation in a Semisolid State;526
16.1;13.1 Introduction;526
16.2;13.2 Concept of Semisolid-State Mixing;526
16.3;13.3 Effect of Temperature on Semisolid-State Mixing;529
16.4;13.4 Role of Other Parameters in Semisolid-State Mixing;536
16.5;13.5 Tensile Properties of Alloys Created by Semisolid- State Mixing;539
16.6;13.6 Generation of Magnesium Matrix Composites;545
16.7;13.7 Engineering Importance of Semisolid-State Mixing;553
16.8;13.8 Summary;554
16.9;References;555
17;Molding Creep-Resistant Alloys;556
17.1;14.1 Introduction;556
17.2;14.2 Elements of Creep Deformation Theory;557
17.3;14.3 Creep in Magnesium and Its Alloys;560
17.4;14.4 Creep Control in Modern Commercial Alloys;563
17.5;14.5 Characteristics of Mg–5Al–2Sr Feedstock for Injection Molding;567
17.6;14.6 Effect of Semisolid Molding on Mg–5Al–2Sr Microstructure;576
17.7;14.7 Summary;583
17.8;References;586
18;Index;588