metallurgical properties of casting materials
TRANSCRIPT
METALLURGICAL PROPERTIES OF
CASTING MATERIALS
DEEPA JINAN
BAPJI DENTAL COLLEGE & HOSPITAL
CONTENTS• Introduction• General characteristics of metals• Casting materials & alloys
DefinitionClassification of casting materialsDesirable properties
• Components of alloysNoble metalsBase metals
• Solidification & crystallization of metals & Alloys• Phase diagrams & dental alloys• Types Of alloys & significance
• General characteristics of metals• Structure & properties of metals• Structure & properties of alloys• Classification of metals & alloy systems• Dental casting alloys
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
• General characteristics of metals• Structure & properties of metals• Structure & properties of alloys• Classification of metals & alloy systems• Dental casting alloys
INTRODUCTION
Metallurgy
Mosby’s dental dictionary. Definition of metallurgy. Restorative Dental Materials. 11th Ed. Missouri:elsivier; 2004. p3904Craig 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.
INTRODUCTION Metals & alloys
Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-117Craig 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
CAST
WROUGHT ALLOY
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
CROWNBIOCOMPATIBILIT
YCORROSION RESISTANCE
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
GENERAL CHARACTERISTICS OF METALSProperties - valence Elelectron configurationMetallic bondResults 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.103-117
• The term alloy system refers to all possible compositions of an alloy
10
0% 100%
0%100%
SILVER
COPPER
CASTING ALLOYSDEFINITION• 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.103-117
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.103-117
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%
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.
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
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
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
NOBLE METALS
PALLADIUM
Hardens as well as whitens the alloy
Raises the fusion temperaturetemperature & 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
NOBLE METALSIRIDIUM & 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
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
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
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
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
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
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 alloymaximum 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
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
BASE METALS
Craig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p449-472
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
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
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.103-117
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.103-117
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
COOLING
NucleationIr
GRAIN REFINERSHigh MP
For even Nucleation
COOLING
GRAINS
Grow into
ENLARGE GRAIN BOUNDARIES
DENDRITES
SOLIDIFICATION & CRYSTALIZATION OF ALLOYS
GRAIN SIZE
COOLING RATE
ALLOY COMPOSITION
PRESENCE OF GRAIN REFINERS
ALLOY STRENGTH
WORKABILITY
SUCEPTIBILITY TO CORROSION
Affects
Depends onFaster 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.
SOLIDIFICATION & CRYSTALIZATION OF ALLOYSSIGNIFICANCE
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
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 PHASEHomogenous composition
MULTI-PHASEAreas with different
composition
BINARY PHASE DIAGRAMS TERTIARY PHASE DIAGRAMS
EQUILIBRIUM PHASE DIAGRAM FOR ALLOYS
Anusavice K J. Equilibrium phases in cast alloys. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.119-141
COOLING CURVE EXPERIMENTS PERFORMED ON A SERIES OF ALLOYS FROM THE A-B SYSTEM
ISOTHERMAL FREEZING
NO SINGLE FREEZING TEMPERATURESOLIDIFY 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
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
13701340
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 SystemLARGE – 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 962-1064Ranges from 1064-1772
LIQUIDUS LINE AT LOWER TEMPERATURE
Heating easier Fewer side reactions
Shrinkage less problematic
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
SOLID SOLUTIONSGOLD 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 & HARDNESSLOWER 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 homogenousPresence of different phases- interact
electrochemicallyCraig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180.
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 AFFINITYHIGH DEGREE OF CHEMICAL AFFINITY – INTERMETALLIC
COMPOUND
CRYSTAL STRUCTURE SAME TYPE OF CRYSTAL STRUCTURE
EUTECTIC ALLOYSSILVER 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.
INTERMETALLIC COMPOUNDSSILVER 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.
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.
EFFECT OF HEAT TREATMENT
RECRYSTALLIZATION & GRAIN GROWTH
COLD WORKED METALS & ALLOYS HEATING / ANNEALING
FIBROUS STRUCTURE GRADUALLY LOST
GRAIN/CRYSTALLINE STRUCTURES REAPPEARS RECRYSTALLIZATION/
GRAIN GROWTHDEPENDS
TEMPERATURE & DURATION OF
HEATINGCraig R G, Powers J M. Nature of Metals and Alloys. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002. p164-180.
ALLOY STRENGTHENING MECHANISMS
Solid solutions
Precipitation hardening
Grain refiners
Cold working
HEATING ALLOYSSECOND PHASE
APPEARS IN BODY OF ALLOY
BLOCKS THE MOVEMENT OF DISLOCATIONS
STRENGTH & HARDNESS INCREASEDAu-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.
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.
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
CASTING GOLD ALLOYSTYPE 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
CASTING GOLD ALLOYSTYPE 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
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% balanceCraig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002.
p449-4724
CASTING GOLD ALLOYSTYPE 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% balanceCraig R G, Powers J M. Noble dental alloys and solders. Restorative Dental Materials. 11th Ed. Missouri: Mosby; 2002.
p449-4724
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
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.
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
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
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
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
METALLURGICAL PROPERTIES OF
CASTING MATERIALS
CONTENTS
• Base metal alloys• Titanium alloys• Comparison between noble metal & base metal
alloys• References
• General characteristics of metals• Structure & properties of metals• Structure & properties of alloys• Classification of metals & alloy systems• Dental casting alloys
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
SOLIDIFICATION & CRYSTALIZATION OF METALS
SOLIDIFICATION
Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-117
Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-117
EQUILIBRIUM PHASE DIAGRAM FOR ALLOYS
Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-117
TYPES OF ALLOYS
SOLID SOLUTIONS
EUTECTIC
INTERMETALLIC COMPOUNDS
Anusavice K J. Solidification and Microstructure of metals. Philips Science of dental materials. 11th ed. Missouri: Elsevier; 2003p.103-117
TYPES OF ALLOYS
GOLD ALLOYS
METAL CERAMIC ALLOYS
BASE METAL ALLOYS
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 ALLOYSBe 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.
ECONOMICALALLERGIC
POTENTIAL
CAN BE ETCHED
CASTING IS EASIER
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
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
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
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
Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
NOBLE METAL ALLOYS
BASE METAL ALLOYS
DENSITY
MODULUS OF ELASTICITY ELONGATION
CASTING ENVIRONMENTTARNISH & CORROSION
ULTIMATE STRENGTH
RANGE OF MELTING TEMPERATURE
FINISHING & POLISHINGCASTABILITY-MOLDABILITY
SOLDERING
BIOCOMPATIBILITY
PORCELAIN BONDING
CASTING SGRINKAGE
NOBLE METAL ALLOYS
BASE METAL ALLOYS
DENSITY
HIGHEST DENSITY
LESS FORCE IN CENTRIFUGAL
CASTING
DENSITYALMOST HALF OF HIGH NOBLE
LOWER DENSITY ALLOWS MORE
RESTORATIONS PER UNIT WEIGHT &
LIGHTERACCELERATES 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.
NOBLE METAL ALLOYS
BASE METAL ALLOYS
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 TECHNIQUEELECTRIC
RESISTANCE/INDUCTION MELTING
Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
NOBLE METAL ALLOYS
BASE METAL ALLOYS
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.
NOBLE METAL ALLOYS
BASE METAL ALLOYS
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.
NOBLE METAL ALLOYS
BASE METAL ALLOYS
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.
NOBLE METAL ALLOYS
BASE METAL ALLOYS
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
NOBLE METAL ALLOYS
BASE METAL ALLOYS
CASTING ENVIRONMEN
T
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.
NOBLE METAL ALLOYS
BASE METAL ALLOYS
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.
NOBLE METAL ALLOYS
BASE METAL ALLOYS
FINISHING & POLISHING
EASILY ACCOMPLISHED
LESS COMPLICATED ARMAMENTARIUM
MORE TIME TO ATTAIN BIOLOGIC SURFACES
REQUIRE HIGH SPEED EQUIPMENT
MORE ABRASIVE TOOLSELECTROLYTIC
POLISHING REQUIRED FOR Co Cr
Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
NOBLE METAL ALLOYS
BASE METAL ALLOYS
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.
NOBLE METAL ALLOYS
BASE METAL ALLOYS
TARNISH & CORROSION
EXCELLENT RESISTANCE
NOBILITY
GOOD RESISTANCE
PASSIVITY
Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
NOBLE METAL ALLOYS
BASE METAL ALLOYS
BIOCOMPATIBILITY
GENERALLY REGARDED AS HAVING GOOD
BIOCOMPATIBILITY
PALLADIUM ALLERGY
CONTAIN COMPONENTS
REGARDED AS TOXIC OR KNOWN ALLERGENS
Ni – KNOWN ALLERGENBe THOUGHT TO BE
CARCINOGENIC
Marzouk MA. Cast restorations. 1st ed. India: All India publishers and distributers; 2001p.307-323.
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
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.
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.
METALLURGICAL PROPERTIES OF
CASTING MATERIALS