Recommandé
Contenu connexe
Tendances
Tendances (20)
Similaire à metallurgical properties of casting materials
Similaire à metallurgical properties of casting materials (20)
Plus de Deepa jinan
Plus de Deepa jinan (7)
Dernier
Dernier (20)
metallurgical properties of casting materials
- 2. DEEPA JINAN BAPJI DENTAL COLLEGE & HOSPITAL
- 3. CONTENTS • Introduction • General characteristics of metals • Casting materials & alloys Definition Classification of casting materials Desirable properties • Components of alloys Noble metals Base metals • Solidification & crystallization of metals & Alloys • Phase diagrams & dental alloys • Types Of alloys & significance
- 4. CONTENTS • Effects of mechanical treatment • Effects of heat treatment • Alloy strengthening mechanisms • Mechanism for corrosion resistance • Casting gold alloys • Metal ceramic alloys • Base metal alloys • Titanium alloys • Comparison between noble metal & base metal alloys • References
- 5. INTRODUCTION Metallurgy Mosby’s dental dictionary. Definition of metallurgy. Restorative Dental Materials. 11th Ed. Missouri:elsivier; 2004. p3904 Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180. Physical and chemical behavior of metals & alloys • Bulk • Atomic levelEffect of mechanical treatment Effect of heat treatment Study of metals and alloys The study of metals and their properties, including separating metals from their ores, the making and compounding of alloys, and the technology and science of working and heat treating metals to alter their physical charachteristics.
- 6. INTRODUCTION Metals & alloys Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-117 Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180. CASTING ALLOYS FINAL STRUCTURE FURTHER MANIPULATED C A S T WROUGHT ALLOY
- 7. INTRODUCTION Significance of Metallurgy in dentistry Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180. Diverse metals & alloys – characteristic behavior Properties of metals - guide in fabrication of cast structures COMPOSITION OF CASTING MATERIAL CLINICAL USE & ENVIRONMENT BUR HARDNESS IMPORTANT CORROSION RESISTANCE LESS IMPORTANT CROWN BIOCOMPATIBILITY CORROSION RESISTANCE
- 8. Properties • Lustre • Opacity • Density • High boiling points & melting points • Solids at room temperature • Thermal conductivity • Electrical conductivity • Ductility & malleability Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-117 GENERAL CHARACTERISTICS OF METALS
- 9. GENERAL CHARACTERISTICS OF METALS Properties - valence Elelectron configuration Metallic bond Results from ↑spatial extension of valence e- when an aggregate of metal atoms is brought close together. +ve charged ionic core +ve charged ionic core +ve charged ionic core +ve charged ionic core +ve charged ionic core +ve charged ionic core Unbound / free valance e- forms cloud or gas equilibrium between electrostatic force s results in inter atomic space Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-
- 10. • The term alloy system refers to all possible compositions of an alloy 10 0% 100% 0%100% SILVER COPPER CASTING ALLOYS DEFINITION • A substance with metallic properties that is composed of two or more chemical elements, at least one of which is a metal Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-
- 11. CLASSIFICATION OF CASTING ALLOYS BASED ON NOBILITY HIGH NOBLE ALLOYS PREDOMINANTLY BASE METAL ALLOYS NOBLE ALLOYS Contains > 40 wt% Au and > 60 wt% of the noble metal elements (Au + Ir + Os + Pd + Pt + Rh + Ru) Contains > 25 wt % of the noble metal elements Contains < 25 wt % of the noble metal elements Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-
- 12. CLASSIFICATION OF CASTING ALLOYS Gladwin M, Bagby M. Materials for fixed indirect Restorations and Prostheses. Clinical aspects of dental materials. China: Lippincott Williams & Wilkins. 2009. p 131-145. Revised ADA Classification, 2003 HIGH NOBLE ALLOYS PREDOMINANTLY BASE METAL ALLOYS NOBLE ALLOYS Contains > 40 wt% Au and > 60 wt% of the noble metal elements (Au + Ir + Os + Pd + Pt + Rh + Ru) Contains > 25 wt % of the noble metal elements Contains < 25 wt % of the noble metal elements TITANIUM & TITANIUM ALLOYS Titanium ≥ 85 wt%
- 13. CLASSIFICATION OF CASTING ALLOYS BASED ON USE CROWN & BRIDGE ALLOYS RPD ALLOYS METAL CERAMIC ALLOYS Gladwin M, Bagby M. Materials for fixed indirect Restorations and Prostheses. Clinical aspects of dental materials. China: Lippincott Williams & Wilkins. 2009. p 131-145.
- 14. CASTING MATERIALS DESIRABLE PROPERTIES PURE ELEMENTS ALLOYS COMBINED Biocompatibility Ease of melting Ease of casting Ease of polishing Little solidification shrinkage Minimal reactivity with the mold material Good wear resistance High strength Excellent corrosion resistance Porcelain Bonding
- 15. NOBLE METALS GOLD Soft and ductile A yellow “Gold” hue • Density of 19.3 gms/cm3 • Melting point of 1063°C, • Boiling point of 2970 °C • CTE of 14.2×10-6/°C Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472 Excellent corrosion resistance
- 16. NOBLE METALS PLATINUM Bluish white metal- tough ductile & malleable Increases strength and corrosion resistance It helps to reduce the grain size • Density of 21.45 gms/cm3 • Melting point of 1769°C • Boiling point of 4530 °C • CTE 8.9×10-6/°C Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472
- 17. NOBLE METALS PALLADIUM Hardens as well as whitens the alloy Raises the fusion temperature temperature & provides tarnish resistance Absorbs large quantities of H₂ when heated • Density of 12.02 gms/cm3 • Melting point of 1552°C • Boiling point of 3980 °C • CTE 11.8×10-6/°C Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472
- 18. NOBLE METALS IRIDIUM & RUTHENIUM Added in very small quantities about 100 to 150 ppm Help to decrease the grain size Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472
- 19. BASE METALS CHROMIUM,COBALT, NICKEL, IRON, COPPER, Reactive with environment Invaluable components of dental casting alloys Influences on physical properties Strengthening effect McCabe J F, Walls A W G. Base metal casting alloys. Applied dental materials. 9th ed. Hong kong; Blackwell Publishing Ltd: 2008. p,71- 79
- 20. BASE METALS SILVER Malleable, ductile white metal Increases strength and hardness In large amounts, it reduces tarnish resistance- combines with S,Cl₂, P • Density 10.4gms/cm3 • Melting point of 961°C, • Boiling point of 2216 °C • CTE is 19.7 ×10-6/°C Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472
- 21. NOBLE METALS COBALT Imparts hardness, strength and rigidity • Density of 8.85 gms/cm3 • Melting point of 1495°C • Boiling point of 2900 °C • CTE 13.8×10-6/°C Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472
- 22. NOBLE METALS NICKEL Decreases • Strength • Hardness • Modulus of elasticity • Fusion temperature • Density of 8.9 gms/cm3 • Melting point of 1453°C • Boiling point of 2730 °C • CTE 13.3×10-6/°C Increases ductility Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472
- 23. BASE METALS Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4 CHROMIUM Passivating effect – corrosion resistance • Density of 7.19 gms/cm3 • Melting point of 1875°C • Boiling point of 2665 °C • CTE 6.2×10-6/°C Increases the melting point & content not to exceed 30 % Acts in solid solution hardening & Precipitation hardening
- 24. BASE METALS COPPER Principal hardener • Density of 7.19 gms/cm3 • Melting point of 1083°C • Boiling point of 2595 °C • CTE 16.5×10-6/°C Reduces the density of gold alloys Reduces resistance to tarnish and corrosion of gold alloy maximum content NOT to exceed 16%. Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472
- 25. BASE METALS ZINC Scavenger for oxygen MELTING SILVER ALLOY WITHOUT ZINC O₂ O₂ SOLIDIFICATION OF SILVER ALLOY WITHOUT ZINC POROSITIES Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472
- 26. BASE METALS GALLIUM Grayish metal • Density of 5.91 gms/cm3 • Melting point of 29.8°C • Boiling point of 2204 °C Oxides are important to bonding of ceramic to metal
- 27. NOBLE METALS GOLD Soft and ductile A yellow “Gold” hue • Density of 19.3 gms/cm3 • Melting point of 1063°C, • Boiling point of 2970 °C • CTE of 14.2×10-6/°C Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472 Excellent corrosion resistance
- 28. SOLIDIFICATION & CRYSTALIZATION OF METALS SOLIDIFICATION FREEZING POINT OR SOLIDIFICATION TEMPERATURE OF PURE METALFUSION TEMPERATURE SUPERCOOLING B’-B – CRYSTALIZATION BEGINS FOR PURE METALS RELEASE OF THE LATENT HEAT OF FUSION CAUSES THE TEMPERATURE TO RISE TO TF LIQUID – HIGH ENERGY STATE SOLID – LOW ENERGY STATE CRYSTALIZATION COMPLETE Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-
- 29. SOLIDIFICATION & CRYSTALIZATION OF METALS SOLIDIFICATION FREEZING POINT OR SOLIDIFICATION TEMPERATURE OF PURE METALFUSION TEMPERATURE SUPERCOOLING B’-B – CRYSTALIZATION BEGINS FOR PURE METALS RELEASE OF THE LATENT HEAT OF FUSION CAUSES THE TEMPERATURE TO RISE TO TF LIQUID – HIGH ENERGY STATE SOLID – LOW ENERGY STATE CRYSTALIZATION COMPLETE Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-
- 30. SOLIDIFICATION & CRYSTALIZATION OF ALLOYS Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180. NUCLEI MOLTEN ALLOY C O O L I N G Nucleation Ir GRAIN REFINERS High MP For even Nucleation C O O L I N G GRAINS Grow into ENLARGE GRAIN BOUNDARIES DENDRITES
- 31. SOLIDIFICATION & CRYSTALIZATION OF ALLOYS GRAIN SIZE COOLING RATE ALLOY COMPOSITION PRESENCE OF GRAIN REFINERS ALLOY STRENGTH WORKABILITY SUCEPTIBILITY TO CORROSION Affects Depends on Faster cooling rate Noble metals Ir, Ru, SMALL GRAINED Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180.
- 32. SOLIDIFICATION & CRYSTALIZATION OF ALLOYS SIGNIFICANCE Typically solidify with a dendritic micro-structure Solidify with an Equiaxed polycrystalline microstructure Equiaxed – grains uniform in size & shape BASE METAL CASTING ALLOYS NOBLE METAL CASTING ALLOYS Fine grainedLarge grained SMALLER THE GRAIN SIZE MORE DUCTILE AND STRONGER PRODUCES A MORE HOMOGENOUS CASTING IMPROVES THE TARNISH RESISTANCE elongated morphology of dendrites Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-117
- 33. PHASE DIAGRAMS & DENTAL ALLOYS Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180. PHASE A state of matter distinct from matter around it ICE WATER ARRANGEMENT OF ATOMS SINGLE PHASE Homogenous composition MULTI-PHASE Areas with different composition BINARY PHASE DIAGRAMS TERTIARY PHASE DIAGRAMS
- 34. EQUILIBRIUM PHASE DIAGRAM FOR ALLOYS Anusavice K J. Equilibrium phases in cast alloys. Philips Science of dental materials. 11th ed. Missouri: Elsevier; COOLING CURVE EXPERIMENTS PERFORMED ON A SERIES OF ALLOYS FROM THE A-B SYSTEM ISOTHERMAL FREEZING NO SINGLE FREEZING TEMPERATURE SOLIDIFY OVER A RANGE COOLING CURVE EXPERIMENTS PERFORMED ON A SERIES OF ALLOYS FROM THE A-B SYSTEM EQUILIBRIUM PHASE DIAGRAM LIQUIDUS TEMPERATURE – FIRST SOLID FORMS SOLIDUS TEMPERATURE – LAST SOLID FORMS LIQUIDUS SOLIDUS
- 35. EQUILIBRIUM PHASE DIAGRAM FOR ALLOYS 65% PALLADIUM & 35 %SILVER COMPOSITION (65WT% Pd) Alloy is in liquid state DASHED LINE PO POINT R Temperature - 1400°c 77% Pd POINT S 57% Pd - Y 71% Pd - W POINT T 52% Pd - T Anusavice K J. Equilibrium phases in cast alloys. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.119-141 1370 1340
- 36. EQUILIBRIUM PHASE DIAGRAM FOR ALLOYS Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-4724 SIGNIFICANCE DISTANCE BETWEEN LIQUIDUS & SOLIDUS LINES SMALL – Ag-Au System LARGE – Au-Pt System Varies for Au-Cu Sytem NARROW LIQUIDUS SOLIDUS RANGE ALLOY IN LIQUID STATE FOR SHORTER LESS SUCEPTIBLE TO OXIDATION &CONTAMINATION Alloy remain partially molten for longer period TEMPERATURE OF LIQUIDUS LINE Ranges from 962-1064 Ranges from 1064-1772 LIQUIDUS LINE AT LOWER TEMPERATURE Heating easier Fewer side reactions Shrinkage less problematic
- 37. ALLOYS Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180. TYPES LIQUID METAL A LIQUID METAL BLIQUID ALLOY ABSOLID ALLOY AB METALS MIXED IN MOLTEN STATE OUTCOMES BASED ON SOLUBILITY OF METALS IN EACH OTHER SOLID SOLUTION - soluble EUTECTIC – not soluble INTERMETALLIC COMPOUND – form specific compound FOLLOWED BY COOLING
- 38. SOLID SOLUTIONS GOLD COPPER SYSTEM Miscible – in any combination – Properties resemble metals forming alloy Au atoms occupy some positions of FCC, Cu atoms occupy some other - random At a certain composition, Au atoms occupy some positions of FCC, Cu atoms occupy some other – specific pattern- ordered solutions HIGHER STRENGTH & HARDNESS LOWER DUCTILITY Melting ranges – Lower :smooth transition between two melting points HIGHER CORROSION RESISTANCE Presence of atoms of unequal size – more difficult for atomic planes to slide Single phase – more homogenous Presence of different phases- interact electrochemically Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180.
- 39. SOLID SOLUTIONS Anusavice K J. Equilibrium phases in cast alloys. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.119-141. FACTORS DETERMINING EXTENT OF SOLID SOLUBILITY OF METALS ATOMIC SIZE SIZE DIFFER BY LESS THAN 15% VALENCE METALS OF SAME VALENCE MORE LIKELY TO FORM SOLID SOULTIONS CHEMICAL AFFINITY HIGH DEGREE OF CHEMICAL AFFINITY – INTERMETALLIC COMPOUND CRYSTAL STRUCTURE SAME TYPE OF CRYSTAL STRUCTURE
- 40. EUTECTIC ALLOYS SILVER COPPER SYSTEM Solidus lower than pure Ag OR Cu779.4 960.5 1083 28.1 % Cu 71.9 % Ag ABEGD - solidus AED – liquidus Meet at mid range Pure eutectic - melting point Eutectic composition Ag-Cu System important in high copper dental amalgam Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180.
- 41. INTERMETALLIC COMPOUNDS SILVER TIN SYSTEM Two metals react to form a specific compound Ag₃Sn important intermetallic compound in dental amalgam Ag₃Sn Intermetallic compound in Ag-Sn System, seen at 26.8wt% of Sn Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180.
- 42. EFFECT OF MECHANICAL TREATMENT COLD / WORK HARDENING CAST INGOT SUBJECTED TO ROLLING, SWAGING, WIRE DRAWING MECHANICAL DEFORMATION WROUGHT STRUCTURE CRYSTALLINE /DENDRITIC STRUCTURE GRAINS BROKEN, ENTANGLED, ELONGATED FIBROUS STRUCTURE SUPERIOR MECHANICAL PROPERTIES EMBRITTLE ALLOYS – LESS DUCTILE Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180.
- 43. EFFECT OF HEAT TREATMENT RECRYSTALLIZATION & GRAIN GROWTH COLD WORKED METALS & ALLOYS HEATING / ANNEALING FIBROUS STRUCTURE GRADUALLY LOST GRAIN/CRYSTALLINE STRUCTURES REAPPEARSRECRYSTALLIZATION/ GRAIN GROWTH D E P E N D S TEMPERATURE & DURATION OF HEATING Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180.
- 44. ALLOY STRENGTHENING MECHANISMS Solid solutions Precipitation hardening Grain refiners Cold working HEATING ALLOYS SECOND PHASE APPEARS IN BODY OF ALLOY BLOCKS THE MOVEMENT OF DISLOCATIONS STRENGTH & HARDNESS INCREASED Au-Pt alloy Fe FePt₃ Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180.
- 45. MECHANISMS FOR CORROSION RESISTANCE Polishing metal restorations Passivation Increasing noble metal content Avoiding dissimilar metal restorations THIN ADHERENT OXIDE PREVENTS DIFFUSION OF O₂ Fe - C Cr Stainless steel Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180.
- 46. GOLD ALLOYS Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4 ADA SPECIFICATION No. 5 High Gold Alloys - >70% Type I Type II Type III Type IV Low Gold Alloys - >10wt%, < 45-50% White Gold Alloys- Silver palladium alloys INLAY GOLD ALLOY CROWN & BRIDGE ALLOY
- 47. CASTING GOLD ALLOYS TYPE I - SOFT HIGHLY DUCTILE BURNISHED EASILY Areas of low occlusal stress designed for simple inlays such as used in class I, III & V cavities PROPERTIES Hardness VHN (50 – 90) Tensile Strength 276 MPa Yield Strength 180 MPa Linear Casting Shrinkage 1.56% Elongation or ductility 18- 46% COMPOSITION Au Ag Cu Pt Pd Zn&Ga 83% 10% 6% - 0.5% balance Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-4724
- 48. CASTING GOLD ALLOYS TYPE II- MEDIUM DUCTILE HIGHER YEILD STRENGTH Inlay or onlay restorations subject to moderate stress, thick three quarter crowns, pontics and full crowns PROPERTIES Hardness VHN (90-120) Tensile Strength 345 MPa Yield Strength 300 MPa Linear Casting Shrinkage 1.37% Elongation or ductility 10 - 40.5% COMPOSITION Au Ag Cu Pt Pd Zn&Ga 77% 14% 7% - 1% balance HARDER Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-4724
- 49. CASTING GOLD ALLOYS TYPE III- HARD NOT DUCTILE AGE HARDENED Inlays subject to high stress and for crown and bridge PROPERTIES Hardness VHN (120-150) Tensile Strength 360 MPa Yield Strength 331MPa Linear Casting Shrinkage 1.42 % Elongation or ductility 5- 39.4 % COMPOSITION Au Ag Cu Pt Pd Zn&Ga 79% 11% 5% - 3.5% balance Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-4724
- 50. CASTING GOLD ALLOYS TYPE IV- EXTRA HARD NOT DUCTILE AGE HARDENED Very high stress, crowns and long span bridges PROPERTIES Hardness VHN (150-200) Tensile Strength 462 MPa Yield Strength 703 MPa Linear Casting Shrinkage 2.03 % Elongation or ductility 3 - 17 % COMPOSITION Au Ag Cu Pt Pd Zn&Ga 56% 25% 14% - 4% balance Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-4724
- 51. CASTING GOLD ALLOYS HEAT TREATMENTS SOFTENING HEAT TREATMENT HEATING FOR 10 MINS AT 700 C THEN QUENCHING Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-4724 AGE HARDENING HEAT TREATMENT HEATING CASTING TO ABOVE 450°C AND THEN ALLOWING IT TO COOL SLOWLY UNTIL TEMP DROPPED TO 200ᵒC FOLLOWED BY QUENCHING
- 52. METAL CERAMIC ALLOYS Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4 REQUIREMENTS They should be able to bond with porcelain. Coefficient of thermal expansion Its melting temperature should be higher than the porcelain firing temperature. It should be able to resist creep or sag. It should not stain or discolor porcelain.
- 53. METAL CERAMIC ALLOYS Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4 Oldest metal ceramic alloys Composition: Gold – 75% to 88% Palladium – Upto 11% Platinum – Upto 8% Silver – 5% Trace elements like Indium, Iron and Tin for porcelain bonding Gold-Platinum -Palladium Biocompatibility Ease of melting Ease of casting Ease of polishing Sag reistance COTE Good wear resistance Hardness Resistance to discolouration Porcelain Bonding Economical
- 54. METAL CERAMIC ALLOYS Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4 Composition: Gold – 39% to 53% Silver – 12% to 22% Palladium – 25% to 35% trace amount of oxidizable elements are added for porcelain bonding Gold-Palladium-Silver Biocompatibility Ease of melting Ease of casting Ease of polishing Sag resistance COTE Good wear resistance Hardness Resistance to discoloration Porcelain Bonding Economical
- 55. METAL CERAMIC ALLOYS Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4 Composition: Palladium – 55% to 60% Silver – 25% to 30% Indium and Tin Palladium – 50% to 55% Silver – 35% to 40% Tin (Little or no Indium trace amount of oxidizable elements are added for porcelain bonding Palladium-Silver Biocompatibility Ease of melting Ease of casting Ease of polishing Sag resistance Thermal compatibility Good wear resistance Hardness Resistance to discoloration Porcelain Bonding Economical
- 56. METAL CERAMIC ALLOYS Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4 Composition: Palladium – 78% to 88% Cobalt – 4% to 10% trace amount of oxidizable elements are added for porcelain bonding Palladium-Cobalt alloy Biocompatibility Ease of melting Ease of casting Ease of polishing Sag resistance Thermal compatibility Good wear resistance Hardness Resistance to discoloration Porcelain Bonding Economical
- 58. CONTENTS • Base metal alloys • Titanium alloys • Comparison between noble metal & base metal alloys • References
- 59. NOBLE METALS Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472 BASE METALS
- 60. SOLIDIFICATION & CRYSTALIZATION OF METALS SOLIDIFICATION Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-
- 61. Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103- EQUILIBRIUM PHASE DIAGRAM FOR ALLOYS
- 62. Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103- TYPES OF ALLOYS SOLID SOLUTIONS EUTECTIC INTERMETALLIC COMPOUNDS
- 63. Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103- TYPES OF ALLOYS GOLD ALLOYS METAL CERAMIC ALLOYS BASE METAL ALLOYS
- 64. BASE METAL ALLOYS Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4 Nickel-chromium Be FREE ALLOYS Be CONTAINING ALLOYS Composition: Nickel – 62% to 77% Chromium – 11% to 22% Boron ,iron, molybdenum, Niobium or columbium and tantalum (trace elements). Composition: Nickel – 62% to 82% Chromium – 11% to 20% Beryllium – 2.0% aluminum, carbon, gallium, iron, manganese, molybdenum, silicon, titanium and /or vanadium are present. ECONOMICAL ALLERGIC POTENTIAL CAN BE ETCHED CASTING IS EASIER
- 65. BASE METAL ALLOYS Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4 Composition: Cobalt - 55 to 65% Chromium - 23 to 30% Nickel - 0 to 20% Molybdenum - 0 to 7% Iron - 0 to 5% Carbon - upto 0.4% Tungsten, Manganese, Silicon and Platinum in traces. COBALT CHROMIUM ALLOY HIGH STRENGTH EXCELLENT CORROSION RESISTANCE POOR BURNISHABILITY
- 66. BASE METAL ALLOYS Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4
- 67. TITANIUM ALLOYS Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4 Properties of titanium: • Relatively light weight • Low density (4.5 g/cm3) • High strength (yield strength = 170-480 MPa; • ultimate strength = 240-550 MPa) • Passivity • Low coefficient of thermal expansion (8.5 x 10–6/°C) • Melting & boiling point of 1668°C & 3260°C “MATERIAL OF CHOICE” IN DENTISTRY OXIDE FORMATION PROPERTY BIOCOMPATIBILITY
- 68. TITANIUM ALLOYS Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4 Difficulties in casting Titanium : -High melting point -High reactivity > 600°C – H, O, N -Difficulty in finishing -Difficulty in welding -Requires expensive equipments LOW DENSITY DIFFICULT TO CAST IN CENTRIFUGAL CASTING COMBINING CENTRIFUGAL, VACUUM, PRESSURE, GRAVITY CASTING WITH ELECTRIC ARC MELTING TECHNOLOGY
- 69. Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323. DENSITY MODULUS OF ELASTICITY ELONGATION CASTING ENVIRONMENT TARNISH & CORROSION ULTIMATE STRENGTH RANGE OF MELTING TEMPERATURE FINISHING & POLISHING CASTABILITY-MOLDABILITY SOLDERING BIOCOMPATIBILITY PORCELAIN BONDING CASTING SGRINKAGE
- 70. DENSITY HIGHEST DENSITY LESS FORCE IN CENTRIFUGAL CASTING DENSITYALMOST HALF OF HIGH NOBLE LOWER DENSITY ALLOWS MORE RESTORATIONS PER UNIT WEIGHT & LIGHTER ACCELERATES FASTER – FORMS COMPLETE CASTING MORE EASILY VERY THIN CROSS SECTION DETAILS TO BE AVOIDED Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
- 71. MELTING RANGE LOWEST MELTING RANGE CAST USING LOW HEAT TECHNIQUE HIGHEST MELTING RANGE GAS AIR FUEL Ca SO₄ DIHYDRATE BONDED INVESTMENTS PHOSPHATE & SILICATE BONDED INVESTMENTS HIGH HEAT TECHNIQUE ELECTRIC RESISTANCE/INDUCTION MELTING Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
- 72. ULTIMATE STRENGTH SUFFICIENT STRENGTH FAILURE NOT CATASTROPHIC DOUBLE TENSILE STRENGTH SELDOM FAILS MECHANICALLY Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
- 73. ELONGATION BURNISHABLE EASIER TO ADJUST MARGINS IN CASE OF DISCREPANCY NOT BURNISHABLE MARGINS TO BE PLACED IN REACHABLE AND REPRODUCABLE AREAS, CLASP ADJUSTMENT DIFFICULT Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
- 74. MODULUS OF ELASTICITY 2-3 TIMES LESS THAN BASE METAL ALLOYS ABRASION RESISTANCE LESS IN COMPARISON HIGH MODULUS OF ELASTICITY GOOD ABRASION RESISTANCE Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
- 75. PORCELAIN BONDING COMMONLY USED FOR FABRICATION OF METAL CERAMIC RESTORATIONS MOSTLY Ni Cr USED FOR METAL CERAMIC McCabe J F, Walls A W G. Gold and Alloys of Noble metals, Applied dental materials. 9th ed. Hong kong; Blackwell Publishing Ltd: 2008. p62-70, McCabe J F, Walls A W G. Base metal casting alloys. Applied dental materials. 9th ed. Hong kong; Blackwell Publishing Ltd: 2008. p71-79
- 76. CASTING ENVIRONMENT LESS SENSITIVE TO CASTING ENVIRONMENT ALLOY LESS SUCEPTIBLE TO CONTAMINANTS MORE CONTROLLED & DEVOID OF CONTAMINANTS PALLADIUM – HIGH AFFINITY FOR OXYGEN – POROSITY CONTAMINANTS ( C,O₂) ADVERSELY CHANGE PROPERTIES OF ALLOY SILVER HAS HIGH AFFINITY FOR OXYGEN – POROSITY & ROUGHNESS Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
- 77. CASTING SHRINKAGE LESS SOLIDIFICATION SHRINKAGE LESS TECHNIQUE SENSITIVE HIGHER SOLIDIFICATION SHRINKAGE DIFFICULT TO PRODUCE RESTORATION WITH SATISFACTORY FIT Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
- 78. FINISHING & POLISHING EASILY ACCOMPLISHED LESS COMPLICATED ARMAMENTARIUM MORE TIME TO ATTAIN BIOLOGIC SURFACES REQUIRE HIGH SPEED EQUIPMENT MORE ABRASIVE TOOLS ELECTROLYTIC POLISHING REQUIRED FOR Co Cr Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
- 79. SOLDERING FAIRLY PREDICTABLE & EASY GOLD SOLDERS FOR HIGH NOBLE. OR SILVER SOLDERS TECHNIQUE SENSITIVE REQUIRE INERT ENVIRONMENT SPECIFIC SOLDER FOR EACH ALLOY Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
- 80. TARNISH & CORROSION EXCELLENT RESISTANCE NOBILITY GOOD RESISTANCE PASSIVITY Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
- 81. BIOCOMPATIBILITY GENERALLY REGARDED AS HAVING GOOD BIOCOMPATIBILITY PALLADIUM ALLERGY CONTAIN COMPONENTS REGARDED AS TOXIC OR KNOWN ALLERGENS Ni – KNOWN ALLERGEN Be THOUGHT TO BE CARCINOGENIC Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
- 82. CONCLUSION NOBLE METAL ALLOYS SUPERIOR TO BASE METAL ALLOYS COST IMPORTANT FACTOR Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323
- 83. REFERENCES • Anusavice K J. Equilibrium phases in cast alloys. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.119-141. • Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103- 117. • Smith E A. A Manual on dental metallurgy and non-metallic Materials 6th Ed. London:J & A Churchill Ltd;1947.p3-4. • Craig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180. • Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472. • Craig R G, Powers J M. Cast and wrought base metal alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449- 472.
- 84. REFERENCES • Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323. • Marzouk MA. The biologic form and choice of materials for cast restorations. 1st ed. India: All India publishers and distributers; 2001p.341-344. • Darvell BW. Metals I, Metal II, Casting alloys. 9th ed. New Delhi: Woodhead publishing INDIA Private limited; 2009. p 280-305, 306- 322, 435-449. • Gladwin M, Bagby M. Materials for fixed indirect Restorations and Prostheses. Clinical aspects of dental materials. China: Lippincott Williams & Wilkins. 2009. p 131-145. • Mosby’s dental dictionary. Definition of metallurgy. 2nd Ed. Missouri:elsevier; 2004. p390.
Notes de l'éditeur
- WHAT EXACTLY IS METALLURGY…??? VERY OFTEN IT IS THOUGHT OF AS THE SCIENCE THAT DEALS WITH THE EXTRACTION OF METALS FROM THEIR ORES… BUT IS SEEING THINGS IN A VERY NARROW SENSE… IN FACT PUT VERY SIMPLY METALLURGY CAN BE SAID TO BE THE….. IT IS THE SCIENCE THAT EXPLAINS THE.. & IT ALSO DESCIRBES THE EFFECTS OF BOTH
- In dentistry, metals represent one of the three major classes of materials used for REHABILITATION OF MISSING STRUCTURES,WHICHIS WHY METALLURGY GAINS A LOT IMPORTANCE , NOW THESE METALS & ALLOYS ARE CAST… FOR TWO DIFFERENT PURPOSES..IN THE FIRST INSTANVE THEY MAY SERVE AS THE FINAL STRUCTURE OR SECONDLY IT MAY BE FURTHER MANIPULATED TO FORM WIRES, BARS, SHEETS, IN WHICH CASE THEY ARE CALLED WROUGHT ALLOYS
- DIVERSE METALS & ALLOYS ARE USED IN DENTISTRY… EACH OF WHICH MAY HAVE A UNIQUE & CHARACHTERISTIC BEHAVIOUR.. THIS BEHAVIOUR OF THE ALLOY IS HEAVILY DEPENDENT ON THE VERY COMPOSITION OF THE ALLOY… THE COMPISITION OF THE ALLOY MUST THUS BE TAKEN INTO CONSIDERATION DEPENDING ON THE CLINICAL USE & THE ENVIRON MENT IN WHICH IT IS USED FOR EGS…
- Specific gravity, ringing sound when struck, high fracture tougness.. They are stronger & denser than most non metallic elements
- Previously mentioned propertie .. of metals are in fact closely related to their valence electron configuration THE OUTERMOST E- s ..around the neutral atoms are loosely bound
- The use of pure metals is limited in dentistry.. This is because pur metals tends to be soft or may corrode easily…. To optimize properties most metals used in dentistry are in fact alloys
- BOTH THE HIGH MP EN COTE AT MAKES IT COMPATIBLE TO BE USEDWITH PORCELAIN
- IN THEPRESENCE OF ZINC.. IT PREFERENTIALLY REACTS WITH THE OXYGEN FORMS A WHITE OXIDE OF LOW DENSITY
- It is important to note that pure metalls have a specific bp mp. Let us now consider the solidification phenpomena that occur duruing thhe freezing of a pure metal… the graph on screen shows the temperature plotted as a function of time when a pure metal is melted end cooled to room temperature. Note the temp decreases steadily from point a to pnt b..increase in temp then occurs from pt b b at b the temp remains constant until time indic by c isreached.. After this temp decreases steadily to room temp
- It is important to note that pure metalls have a specific bp mp. Let us now consider the solidification phenpomena that occur duruing thhe freezing of a pure metal… the graph on screen shows the temperature plotted as a function of time when a pure metal is melted end cooled to room temperature. Note the temp decreases steadily from point a to pnt b..increase in temp then occurs from pt b b at b the temp remains constant until time indic by c isreached.. After this temp decreases steadily to room temp
- BYADDITION OF SMALL AMTS OF ELEMENTS SUCH AS BY VIRTUE OF HAVING A HIGH MP THEY REMAIN UNMOLTEN AND SERVE AS NUCLEATING CENTRES THROUGHOUT THE ALLOY
- In a mixture of ice and water there are two phases because although ice en wat are same chemically thy each have distinct arrangement of atoms… ice has crystalline arrang whereas water has random atomic arrangemt… similarly aa solid dental alloy may also hav one phase if the composition of the alloy is essentially homogenous… if the alloys has areas where compositions are different it is called multiphase alloy… this distinction is imp wrt strength corrosion en other properties
- Consider the graph on screen .. Temp plotted as a function of time… obtained when cooling curve expt are carried out on a series of alloys from the ab system… CURVES 1 & 6 ARE FOR PURE METALS SHOWS USUAL SITUATION OF ISOTHERMAL FREEZING BUT WITHOUT SUPERCOOLING.. CURVES 2TO 5 SHOW THAT SOLID SOLUTION ALLOYS DO NOT HAV A SINGLE FREEZING TEMP BUT SOLIDIFY OVER A TEMP RANGE .. THE REGION LABELLED L=S IS A TWO PHASE REGION COMPOSEDOF SOLID AND LIQUID….THESE COOLING CURVES CAN NOW BE USED TO DETERMINE ….. EQUILIBRIUM PHASE DIAGRAM… THE TEMP AT WHICH THE FIRST SOLID FORMS IS CALLED THE LIQUIDUS EN TEMP AT WHICH LAST SOLID FORMS IS CALLED SOLIDUS….WHEN THESE POINTS ARE CONNECTED WITH SMOOTH CURVES THE EQUILIB PHASE DIAG RESULTS… THE UPPER CURVE IS CALLEED LIQUIDUS EN LOWER CURVE CALLED SOLIDUS… SINCE THE ALLOYS ARE ENTIRELY SOLID FOR TEMP EN COMPOS BELOW THIS CURE
- NOW CONSIDER COOLING OF 65 EN 35 AS INDIC BY LINE PO PERPEND TO BASE LINE… IF POINT ON PO CORRESPONDS TO THE TEMP OF 1500 IS CONSIDERED THE ALLOY ISCLEARLY IN LIQUIDSTATE… WWHEN TEMP DECREASES TO APPROX 1400 THE VERTICAL LINE PO TOUCHES THE LIQUIDUS CURVE AT POINT REN THE FIRST SOLID FORMS… HOWEVER COMPOSITION IS DIFFEENT FROM PARENT METAL 65 PD EN 35 SILVERTO DETERMINETHIS COMPOA LINE RM ISDRAWN PARALELL TO BASELINE UNTIL IT INTERSECTS SOLIDUS CURVE AT POINT M.NOW THOS POINT OF INTTERSECTION IS PROJECTED TO THE BASELINE TO DETERMINE THE COMPOSITION OF FIRST SOLID FORMED WHICH IS EQUAL TO..WHEN TEMP DECREASES TO POINT S.. COMPOS IS DETERMINED BY DRAWING LINE YW LOCATING ITS POINT OF INTERSECTION WITH SOLIDUS EN LIQUIDUS
- IN THIS PHASE DIAGRAM WHAT STANDS OUT IS THAT THE LIQUIDUS EN SLIDUS MEET AT MID RANGE COMPOSITION.. THE SOLIDUS IS LOWER AT 779.4 THAN EITHER PURE AG OR CU… THIS LIQUID SOLIDUS CONFIGURATION IS CHARACTERISTIC OF A EUTECTIC ALLOY SYSTEM…..
- Pd > 25%
- HEATING FOR 10 MINS AT 700 C THEN COOLING intermediate phases are changed to an ordered solid solution
- It is important to note that pure metalls have a specific bp mp. Let us now consider the solidification phenpomena that occur duruing thhe freezing of a pure metal… the graph on screen shows the temperature plotted as a function of time when a pure metal is melted end cooled to room temperature. Note the temp decreases steadily from point a to pnt b..increase in temp then occurs from pt b b at b the temp remains constant until time indic by c isreached.. After this temp decreases steadily to room temp
- It is important to note that pure metalls have a specific bp mp. Let us now consider the solidification phenpomena that occur duruing thhe freezing of a pure metal… the graph on screen shows the temperature plotted as a function of time when a pure metal is melted end cooled to room temperature. Note the temp decreases steadily from point a to pnt b..increase in temp then occurs from pt b b at b the temp remains constant until time indic by c isreached.. After this temp decreases steadily to room temp
- It is important to note that pure metalls have a specific bp mp. Let us now consider the solidification phenpomena that occur duruing thhe freezing of a pure metal… the graph on screen shows the temperature plotted as a function of time when a pure metal is melted end cooled to room temperature. Note the temp decreases steadily from point a to pnt b..increase in temp then occurs from pt b b at b the temp remains constant until time indic by c isreached.. After this temp decreases steadily to room temp
- It is important to note that pure metalls have a specific bp mp. Let us now consider the solidification phenpomena that occur duruing thhe freezing of a pure metal… the graph on screen shows the temperature plotted as a function of time when a pure metal is melted end cooled to room temperature. Note the temp decreases steadily from point a to pnt b..increase in temp then occurs from pt b b at b the temp remains constant until time indic by c isreached.. After this temp decreases steadily to room temp
- SECONDARY FLARES, DELICATE INTERNAL BOXES, VERY SMALL CAST PINS
- Noble metal alloys have been known to fail ,,, but even in case of failure it is not catastrophic
- IS A MEASURE OF DUCTILITY, HOWEVER FOR CROWN & BRIDGE APPLICATIONS . A LOW VALUE OF ELONGATION IS NOT MUCH OF A CONCERN CAUSE PERMANENT DEFORMATION OF ALLOY IS NOT DESIRABLE
- ADDITIONAL REQUIREMENTS – THERMAL STABILITY BONDING TO CERAMIC COMPATIBILTY TO CERAMIC SUPPORT FOR CERAMIC
- THERE IS PERSISTENT RISK OF SOLDER FAILURE EN CHANGE IN COMPOSITION OF PARENT METAL
- MORE THAN 1 % NI.. 0.02% BE…. TI EN ALLOYS OF THIS METAL INCLUDING VANADIUM ARE KNOWN TO HAVE FAVOURABLE BIOCOMPATI… EN ARE LIKELY TO BECOME WIDELY USED FOR APPLICATIONS IN FUTURE..AT PRESENT RESTRICTED TO IMPLANTSTHERE IS PERSISTENT RISK OF SOLDER FAILURE EN CHANGE IN COMPOSITION OF PARENT METAL
- Several years ago the choice of an alloy was simple.as therewas No other choice than four types of gold alloy. At present these choices are difficult to make DUE TO VARIOUS ALLOYS AVAILABLE…it is thus a dentists duty to understant the properties of the cast materials used and to prepare the tooth and manipulate the materials to get the.best out of them. It is our professional duty too inform patients of the advantages as well as the possible drawbacks of the materials that may be used. without doubt gold alloys are sup to.. however ultimately it all boils down to patient affordability .
- 390