《TANTALUM AND NIOBIUM》

1.HISTORY AND OCCURRENCE1

1.1.History1

1.2.Occurrence2

1.3.Source3

1.4.Concentration10

1.5.Reserves of Tantalum and Niobium11

1.5.1.Nigeria12

1.5.2.Uganda12

1.5.3.Tanganyika12

1.5.4.Norway13

1.5.5.Canada13

1.5.6.Brazil13

2.CONSUMPTION AND USES OF TANTALUM AND NIOBIUM17

2.1.Consumption17

2.2.Uses18

2.2.1.Carbon,low alloy and high chromium steels20

2.2.2.Ferritic type stainless steels20

2.2.3.Austenitic type stainless steels21

2.2.4.High temperature alloys(super-alloys)26

2.2.5.Effect of niobium on nickel-molybdenum alloys28

2.2.6.Effect of niobium on oxidation resistance of some alloys28

2.2.7.Production of ferro-niobium28

2.2.8.Uses of niobium in the welding of stain-less steels31

2.2.9.Inert gas welding electrodes33

2.2.10.Hard metals(cemented carbides)33

2.2.11.Tantalum carbide,silicide and boride for high-temperature applications38

2.2.12.Magnets38

2.2.13.Tantung alloys38

2.2.14.Special alloys40

2.2.15.Catalysts40

2.2.16.Glass40

2.2.17.Metal to ceramic seal41

2.2.18.Chemical equipment41

2.2.19.Spinnerettes43

2.2.20.Electronic applications43

2.2.21.Furnace equipment44

2.2.22.Surgical applications45

2.2.23.Capacitors45

2.2.24.Crucible material59

2.2.25.Nuclear energy developments60

2.2.26.Future high-temperature niobium base alloy materials62

3.EXTRACTION OF TANTALUM AND NIOBIUM FROM THEIR ORES67

3.1.Fusion with Alkaline Fluxes67

3.1.1.Fusion with sodium hydroxide or sodium carbonate67

3.1.2.Fusion with potassium hydroxide or potassium carbonate68

3.1.3.Fusion with a mixture of sodium hydroxide and sodium carbonate69

3.1.4.Fusion with a mixture of sodium car-bonate and sodium nitrate69

3.1.5.Fusion with a mixture of sodium per-oxide and caustic soda70

3.2.Fusion with Acid Fluxes70

3.2.1.Fusion with potassium bisulphate70

3.2.2.Fusion with sodium pyrosulphate71

3.2.3.Fusion with potassium hydrogen fluoride71

3.3.Digestion with Acid Solutions71

3.3.1.Digestion with hydrofluoric acid71

3.3.2.Digestion with hydrofluoric acid and oxalic acid72

3.3.3.Digestion with sulphuric acid73

3.3.4.Digestion with a mixture of sulphuric acid and ammonium sulphate74

3.3.5.Simultaneous decomposition of pyro-chlore and extraction with methyl iso-butyl ketone acidified with hydrofluoric acid74

3.4.Digestion with an Alkaline Solution75

3.4.1.Conversion to ferro-alloy followed by digestion with caustic soda solution75

3.5.Chlorination75

3.5.1.Chlorination of mixed crude carbides75

3.5.2.Chlorination of ferro-alloy77

3.5.3.Recovery of niobium from titanium minerals by chlorination of mineral carbon mixtures80

3.5.4.Chlorination of low grade niobium con-centrates86

4.SEPARATION OF TANTALUM AND NIOBIUM AND THEIR PURIFICATION90

4.1.Separation Involving the Fractional Crystallization of the Potassium Double Fluorides(Marignac Process)90

4.1.1.Tantalum operations at Fansteel Metallurgical Corporation93

4.1.2.Tantalum operations at Siemens＆Halske A.G.94

4.1.3.Niobium operations at Siemens＆Halske A.G.96

4.1.4.Niobium operations at Fansteel Metallurgical Corporation96

4.2.Separation of Titanium and Tin from Tantalum and Niobium101

4.2.1.Separation by fractional hydrolysis101

4.2.2.Separation by precipitation from hydrogen-peroxide solution101

4.2.3.Separation by selective precipitation with salicylic acid or ammonium salicylate101

4.2.4.Separation by leaching pyrosulphate melts with sulphuric acid containing tannin102

4.2.5.Separation by leaching earth acids with hydrochloric-oxalic acid mixtures102

4.2.6.Separation by the tartaric acid hydrolysis method102

4.2.7.Separation by chlorination with carbon tetrachloride or thionyl chloride103

4.2.8.Separation by selective solution of mixed chlorides in carbon tetrachloride106

4.3.Separation by Miscellaneous Methods Other Than Those Involving the Marignac Method,Chlorination,Ion Exchange or Liquid-Liquid Extraction106

4.3.1.Separation by selective acid extraction of sodium bisulphate fusion107

4.3.2.Separation by hydrolysis of reduced solu-tions107

4.3.3.Separation by selective precipitation with the aid of urea107

4.3.4.Separation by selective reduction of mixed oxides followed by acid digestion108

4.3.5.Separation by electrolysis111

4.3.6.Separation by selective extraction of mixed chlorides by liquid sulphur dioxide or sulphuryl chloride111

4.3.7.Separation by selective precipitation with tannin113

4.3.8.Separation by selective solution of mixed oxides with hydrochloric-oxalic acids113

4.4.Separation by Methods Involving Chlorination114

4.4.1.Separation by direct chlorination114

4.4.2.Separation by selective reduction of oxides followed by chlorination115

4.4.3.Separation by selective nitriding followed by chlorination116

4.4.4.Separation by reduction of mixed chlorides116

4.4.5.Separation by partial reduction of penta-chloride mixtures with aluminium118

4.4.6.Separation by selective reduction of mixed chlorides by hydrogen120

4.4.7.Separation by selective chlorination after partial hydrolysis124

4.4.8.Separation by fractional distillation of mixed chlorides127

4.4.9.Separation by reaction between halides of aluminium and mixed oxides128

4.5.Separation by Ion Exchange129

4.5.1.Separation using Dowex-1 and hydro-chloric-hydrofluoric acids129

4.5.2.Separation using Dowex-2 and oxalic acid130

4.5.3.Separation using Deacidite-FF and hydro-chloric-hydrofluoric acids131

4.5.4.Separation using Dowex-2 and hydro-chloric acid131

4.5.5.Separation using Dowex-1 and hydro-chloric-hydrofluoric acids131

4.6.Separation by Chromatographic Adsorption133

4.6.1.Determination of total tantalum and nio-bium in presence of activated cellulose133

4.6.2.Separation of tantalum and niobium in presence of activated cellulose134

4.6.3.Separation of tantalum and niobium in presence of activated alumina136

4.7.Separation by Liquid-Liquid Extraction136

4.7.1.Methyl ethyl ketone-hydrofluoric acid system137

4.7.2.Methyl-dioctyamine/xylene-hydrochloric acid system138

4.7.3.Tribenzylamine/chloroform or methylene chloride-hydrochloric or sulphuric acid system139

4.7.4.Di-isopropyl-mineral acid systems141

4.7.5.Butyl phosphoric acid/n-butyl ether-nitric and oxalic acids systems142

4.7.6.Di-isobutylcarbinol-mineral acid systems143

4.7.7.Investigation into industrial application of liquid-liquid extraction145

4.7.8.Methyl isobutyl ketone-hydrofluoric-nitric acid systems applied to low-grade concentrates159

4.7.9.Methyl isobutyl ketone-hydrofluoric acid with hydrochloric,nitric or sulphuric acid161

4.7.10.Methyl isobutyl ketone-hydrofluoric acid system applied to columbite164

4.7.11.Methyl isobutyl ketone-hydrofluoric acid system with addition of sulphuric acid168

4.7.12.Tributyl phosphate-hydrofluoric-nitric acid or sulphuric acid systems171

4.7.13.Simultaneous decomposition of pyro-chlore and extraction with methyl iso-butyl ketone acidified with hydro-fluoric acid173

5.PRODUCTION OF TANTALUM AND NIOBIUM179

5.1.Reduction of Oxides181

5.1.1.Reduction with carbon181

5.1.2.Reduction with hydrogen188

5.1.3.Reduction with magnesium189

5.1.4.Reduction with calcium190

5.1.5.Reduction with aluminium193

5.1.6.Reduction with mischmetall194

5.1.7.Reduction with silicon195

5.2.Reduction of Halides196

5.2.1.Reduction of potassium or sodium double fluoride salts196

5.2.2.Reduction of tantalum and niobium chlorides201

5.3.Thermal Dissociation207

5.3.1.Thermal dissociation of halides207

5.3.2.Coating metals with tantalum or niobium210

5.4.Electrowinning211

5.4.1.Operations at Fansteel Metallurgical Corporation211

5.4.2.Bath composition216

5.4.3.Effect of bath composition on particle size218

5.4.4.Effect of temperature and current density on particle size218

5.4.5.Gases evolved during electrolysis220

5.4.6.Decomposition potential222

5.4.7.Crucible materials222

5.4.8.Leaching the metal deposit224

5.4.9.Anode effect226

5.4.10.Volatility of potassium tantalum fluoride226

5.4.11.Function of potassium tantalum fluoride227

5.4.12.Other methods of electrowinning228

5.5.Comparison of Tantalum Produced by Sodium Reduction and Electrowinning234

5.6.Electroplating Niobium and Tantalum on Other Metals239

6.CONSOLIDATION244

6.1.Consolidation by Powder Metallurgy245

6.1.1.Tantalum operations at Siemens＆Halske A.G.245

6.1.2.Tantalum operations at Fansteel Metal-lurgical Corporation249

6.1.3.Tantalum operations at Murex Limited250

6.1.4.Laboratory investigations of the sintering of tantalum powder253

6.1.5.Niobium operations at Fansteel Metallurgical Corporation266

6.1.6.Niobium sintering in the United Kingdom267

6.1.7.Reactions during vacuum sintering of tantalum and niobium277

6.1.8.Summary of sintering practices for tantalum and niobium292

6.2.Purification of Consolidated Niobium or Tantalum295

6.2.1.Floating-zone melting295

6.2.2.Cage melting300

6.3.Electron Beam Melting300

6.3.1.Laboratory furnace300

6.3.2.Commercial application303

6.3.3.Purification of niobium305

6.4.Arc-Melting Tantalum and Niobium306

6.4.1.Development of the arc-melting technique306

6.4.2.Removal of impurities during arc melting309

6.4.3.Arc-melting purified metal313

7.FABRICATION318

7.1.Work Hardening318

7.2.Annealing318

7.3.Forging322

7.4.Sheet Rolling322

7.5.Rod Rolling and Swaging323

7.6.Wire Drawing323

7.7.Tube Production324

7.8.Press-work324

7.9.Spinning324

7.10.Machining326

7.10.1.Turning326

7.10.2.Screw cutting326

7.10.3.Drilling327

7.10.4.Grinding327

7.10.5.Shaping and Milling327

7.10.6.Polishing328

7.11.Riveting329

7.12.Welding329

7.12.1.Inert gas arc welding330

7.12.2.Resistance welding335

7.12.3.Carbon arc welding339

7.12.4.Electronic welding339

7.13.Brazing and Soldering341

7.14.Electroplating Other Metals on Niobium342

7.15.Scrap Recovery344

8.PHYSICAL AND STRUCTURAL PROPERTIES346

8.1.Mass346

8.1.1.Density346

8.2.Thermal Properties346

8.2.1.Melting point346

8.2.2.Boiling point346

8.2.3.Vapour pressure346

8.2.4.Thermal expansion348

8.2.5.Thermal conductivity352

8.2.6.Specific heat354

8.2.7.Heat capacity356

8.2.8.Entropy357

8.2.9.Latent heat of fusion358

8.2.10.Latent heat of vaporization358

8.2.11.Heat of combustion358

8.3.Electrical Properties358

8.3.1.Volume conductivity358

8.3.2.Electrlcal resistivity358

8.3.3.Temperature coefficient of resistivity361

8.3.4.Superconductivity361

8.3.5.Thermoelectric power362

8.3.6.Electrochemical equivalent366

8.3.7.Standard electrode potential366

8.4.Magnetic Properties366

8.4.1.Magnetic susceptibility366

8.4.2.Hall effect369

8.5.Optical,Thermionic and Electronic Properties370

8.5.1.Spectral emissivity370

8.5.2.Total emissivity370

8.5.3.Total radiation371

8.5.4.Line spectra371

8.5.5.Refractive index371

8.5.6.Ionization potential371

8.5.7.Electron emission371

8.5.8.Work function372

8.5.9.Secondary emission372

8.5.10.Positive ion emission372

8.5.11.Radiation capacity372

8.5.12.Electronic configuration372

8.6.Crystallographic Data372

8.6.1.Structure type372

8.6.2.Lattice constant373

8.6.3.Schonflies space group373

8.6.4.Interatomic distance373

8.7.Deformation Mechanisms,Recrystallization,Grain Growth and Preferred Orientation373

8.7.1.Deformation mechanisms373

8.7.2.Recrystallization and grain growth380

8.7.3.Preferred orientation384

8.8.Atomic and Nuclear Properties385

8.8.1.Atomic properties385

8.8.2.Neutron data385

8.8.3.Isotopes387

8.9.χ-ray Data391

8.9.1.χ-ray spectra391

9.MECHANICAL PROPERTIES396

9.1.Elastic Properties396

9.1.1.Modulus of elasticity396

9.1.2.Longitudinal wave velocity396

9.1.3.Shear wave velocity396

9.1.4.Wave vibration frequency397

9.1.5.Shear modulus398

9.1.6.Poisson's ratio398

9.2.Tensile Properties398

9.2.1.Effect of temperature398

9.2.2.Effect of rolling direction403

9.2.3.Effect of strain rate on the room tempera-ture properties406

9.2.4.Effect of oxygen,nitrogen and hydrogen407

9.2.5.Effect of annealing407

9.2.6.Effect of alloying408

9.2.7.Effect of pressure410

9.2.8.Effect of recrystallization temperature412

9.2.9.Effect of neutron irradiation412

9.2.10.Variation of properties with method of production415

9.2.11.Impact properties416

9.2.12.Brittle-to-ductile transition temperature416

9.3.Hardness417

9.3.1.Effect of annealing temperature417

9.3.2.Effect of cold working420

9.3.3.Effect of temperature422

9.3.4.Effect of oxygen,nitrogen and hydrogen422

9.4.Fatigue422

9.5.Creep425

9.6.Compressibility427

10.CORROSION BY CHEMICALS,GASES AND LIQUID METALS431

10.1.Chemical Corrosion431

10.1.1.Tantalum-general431

10.1.2.Niobium—general432

10.1.3.Comparison between niobium and tanta-lum and corrosion resistance of niobium and tantalum alloys433

10.1.4.Embrittlement of niobium by alkalis439

10.1.5.Embrittlement of tantalum in uranyl sulphate solution439

10.1.6.Reaction of niobium with water439

10.1.7.Reaction of tantalum with steam440

10.1.8.Electrochemical behaviour and properties of oxide films440

10.2.Reactions with Gases445

10.2.1.Hydrogen with tantalum445

10.2.2.Hydrogen with niobium458

10.2.3.Nitrogen with tantalum466

10.2.4.Nitrogen with niobium475

10.2.5.Oxygen with tantalum486

10.2.6.Oxygen with niobium499

10.2.7.Carbon dioxide with tantalum and niobium515

10.2.8.Protection of niobium and tantalum against oxidation515

10.2.9.Behaviour of refractory oxides in contact with niobium at elevated temperatures531

10.3.Corrosion by Liquid Metals533

10.3.1.Bismuth with tantalum533

10.3.2.Bismuth with niobium533

10.3.3.Lead with tantalum534

10.3.4.Lead with niobium534

10.3.5.Lithium with tantalum and niobium535

10.3.6.Mercury with tantalum and niobium535

10.3.7.Potassium and potassium-sodium allors with tantalum535

10.3.8.Potassium and potassium-sodium alloys with niobium535

10.3.9.Sodium with tantalum535

10.3.10.Sodium with niobium536

10.3.11.Thallium with tantalum and niobium536

10.3.12.Tin with tantalum536

10.3.13.Tin with niobium536

10.3.14.Uranium with tantalum536

10.3.15.Uranium with niobium536

10.3.16.Zinc with tantalum537

10.3.17.Zinc with niobium537

11.BINARY ALLOY SYSTEMS544

11.1.Theoretical Considerations544

11.1.1.Predicted behaviour546

11.1.2.Other considerations547

11.2.Binary Systems548

11.2.1.Aluminium alloys548

11.2.2.Arsenic alloys550

11.2.3.Beryllium alloys550

11.2.4.Boron alloys550

11.2.5.Carbon alloys555

11.2.6.Chromium alloys558

11.2.7.Cobalt alloys561

11.2.8.Copper alloys566

11.2.9.Gallium alloys567

11.2.10.Germanium alloys567

11.2.11.Gold alloys567

11.2.12.Hafnium alloys567

11.2.13.Hydrogen alloys569

11.2.14.Iridium alloys578

11.2.15.Iron alloys579

11.2.16.Lead alloys585

11.2.17.Manganese alloys586

11.2.18.Molybdenum alloys586

11.2.19.Nickel alloys590

11.2.20.Nitrogen alloys592

11.2.21.Osmium alloys598

11.2.22.Oxygen alloys600

11.2.23.Palladium alloys620

11.2.24.Phosphorus alloys620

11.2.25.Platinum alloys622

11.2.26.Potassium alloys623

11.2.27.Rhenium alloys623

11.2.28.Rhodium alloys626

11.2.29.Ruthenium alloys627

11.2.30.Silicon alloys627

11.2.31.Silver alloys632

11.2.32.Sodium alloys632

11.2.33.Sulphur alloys633

11.2.34.Tantalum-niobium635

11.2.35.Thorium alloys637

11.2.36.Tin alloys638

11.2.37.Titanium alloys639

11.2.38.Tungsten alloys642

11.2.39.Uranium alloys647

11.2.40.Vanadium alloys653

11.2.41.Zinc alloys657

11.2.42.Zirconium alloys657

12.SOME COMPOUNDS OF NIOBIUM AND TANTALUM671

12.1.Nitrogen Compounds671

12.1.1.Production of niobium nitride671

12.1.2.Production of tantalum nitride673

12.1.3.Properties of niobium nitride673

12.1.4.Properties of tantalum nitride675

12.1.5.Binary systems of nitrides and carbides of niobium,zirconium,titanium and vanadium675

12.2.Carbon Compounds676

12.2.1.Production of niobium carbide676

12.2.2.Production of tantalum carbide677

12.2.3.Properties of niobium carbide,NbC681

12.2.4.Properties of tantalum carbide682

12.2.5.Applications683

12.2.6.Sintering tantalum carbide684

12.2.7.Systems involving niobium and tantalum carbides684

12.3.Silicon Compounds686

12.3.1.Production of niobium silicide686

12.3.2.Production of tantalum silicide687

12.3.3.Properties of niobium silicides688

12.3.4.Properties of tantalum silicides688

12.3.5.Systems involving niobium and tantalum silicides690

12.4.Boron Compounds691

12.4.1.Production of niobium boride691

12.4.2.Production of tantalum boride695

12.4.3.Properties of niobium boride695

12.4.4.Properties of tantalum boride697

12.4.5.Tantalum-niobium-carbon-boron systems698

12.4.6.Mutual solubilities of metal diborides699

APPENDIX Ⅰ.CHEMICAL ANALYSIS706

Ⅰ.1.Historical706

Ⅰ.2.Methods of Analysis707

Ⅰ.2.1.Estimation of mixed pentoxides707

Ⅰ.2.2.Separate estimation of tantalum and niobium709

APPENDIX Ⅱ.METALLOGRAPHIC TECHNIQUES FOR TANTA-LUM AND ITS ALLOYS717

Ⅱ.1.Metallographic Preparation717

Ⅱ.1.1.By abrasion polishing717

Ⅱ.1.2.By chemical polishing(bright dip)719

Ⅱ.1.3.By electropolishing720

Ⅱ.2.Etching721

Ⅱ.3.Miscellaneous728

Ⅱ.4.Anodic Oxidation728

APPENDIX Ⅲ.SELECTED THERMODYNAMIC DATA FOR SOME COMPOUNDS OF TANTALUM AND NIOBIUM730

Ⅲ.1.Diffusion730

Ⅲ.2.Heat and Free Energy of Formation732

Ⅲ.2.1.Tantalum and niobium oxides732

Ⅲ.2.2.Tantalum and niobium borides733

Ⅲ.2.3.Tantalum and niobium carbides734

Ⅲ.2.4.Tantalum and niobium nitrides734

Ⅲ.2.5.Tantalum and niobium silicides735

Ⅲ.2.6.Tantalum and niobium halides735

Ⅲ.3.Fusion and Vaporization Data for Tantalum and Niobium Halides736

Ⅲ.4.Heat Contents and Entropies737

Ⅲ.4.1.Tantalum and niobium oxides737

Ⅲ.4.2.Tantalum and niobium halides738

Ⅲ.5.Miscellaneous Data on Reduction of Nb2O5738

Ⅲ.5.1.Carbon739

Ⅲ.5.2.Aluminium739

Ⅲ.5.3.Silicon739

AUTHOR INDEX741

SUBJECT INDEX—TANTALUM751

SUBJECT INDEX—NIOBIUM759