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BY
HRISHIKESH D. GHEWADE
(ROLL NO. 212215011)
M.Tech (Material Science and Engg.) 1st Year
NIT TRICHY
COMPOSITION OF MMC
 MMC’s are made by dispersing a reinforcing material into a metal matrix. The
reinforcing surface can ...
MANUFACTURING PROCESSES
A] Continuously Reinforced Composites:
- Vacuum Hot Pressing (VHP)
B] Discontinuously Reinforced C...
BACKGROUND
• Before understanding the mechanism of any processing method, it is
necessary to take a prior knowledge of som...
PREFORM PREPARATION
A. Adsorption and Wetting:
 Good wettability is needed to generate a strong interface that will
allow...
 Example - 1. Coatings of SiC on boron fibre for Al matrices.
2. B4C coating on boron fibres for Titanium matrices.
C. Ma...
INTRODUCTION TO SQUEEZE CASTING
 Squeeze casting is the combination of the casting and forging
processes that can be done...
PRINCIPLE
• Applying pressure on the solidification of molten metal could
change melting point of alloys which enhances th...
CLASSIFICATION
Squeeze
Casting
Direct Squeeze Casting
Without metal
movement
With metal
movement
Indirect Squeeze Casting
...
DIRECT SQUEEZE CASTING
 The pressure for the infiltration of the prefabricated preforms is
applied directly to the melt.
...
3/18/2016 Squeeze casting 11
INDIRECT SQUEEZE CASTING
 The metal is injected into the die cavity by a small diameter piston
 Pressure is transmitted ...
3/18/2016 Squeeze casting 13
Squeeze Casting Infiltration process has the following steps:
• A preform of dispersed phase (particles, fibers) is placed...
List of variables and parameters
 Molten metal pouring temperature;
 Melt volume;
 Melt quality and quantity;
 Preform...
Theoretical background: Effect of
pressure on solidification behaviour
of alloy:
• The application of pressure during soli...
• Substituting the appropriate thermodynamic equation for volume, the
effect of pressure on freezing point may roughly be ...
SQUEEZE CASTING
OF
ALUMINUM METAL MATRIX
COMPOSITES
3/18/2016 Squeeze casting 18
 Among all the MMC’s Aluminum metal matrix composites are
finding increased applications, because of their improved mecha...
- Role:
1) the decrease of grain size
2) Decreasing SDAS
3) Reduction of porosity
4) increase in heat transfer coefficient...
3/18/2016 Squeeze casting 21
3/18/2016 Squeeze casting 22
3) Solidification Rate:
- Very high
- The relation between the grain size “d” and the cooling...
• Conclusions:
- the grain size increased when the cooling rate decreased
- The shorter the solidification time, the highe...
5) Porosity and Mechanical properties:
• The applied pressure increases the volume fraction of the Al-rich α-phase, and
de...
CONCLUSIONS
1. The optimum pressure used in the squeeze casting of Aluminium
alloys and composites, which gives a better m...
ADVANTAGES
Elimination of porosity and shrinkage
100% casting yield
Attainment of greater part details
Good surface fi...
DISADVANTAGES
 Costs are very high due to complex tooling.
 No flexibility as tooling is dedicated to specific component...
COMPARISON
3/18/2016 Squeeze casting 28
REFERENCES
1. M.R. Ghomashchi, A. Vikhrov, “Squeeze casting: an overview”,
Journal of Materials Processing Technology 101 ...
3/18/2016 Squeeze casting 30
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Squeeze Casting

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Squeeze casting is one of the widely used processing method for Metal Matrix Composites (MMC's) after stir casting. This presentation gives an overall idea of process, its parameter and case study of Aluminum MMC's.

Published in: Engineering

Squeeze Casting

  1. 1. BY HRISHIKESH D. GHEWADE (ROLL NO. 212215011) M.Tech (Material Science and Engg.) 1st Year NIT TRICHY
  2. 2. COMPOSITION OF MMC  MMC’s are made by dispersing a reinforcing material into a metal matrix. The reinforcing surface can be coated to prevent a chemical reaction with metal matrix.  For example: Carbon fibres are commonly used in aluminium matrix to synthesize composite.  A matrix is usually a lighter metals such as Aluminium, Magnesium or Titanium and provides a compliant support for the reinforcement.  The reinforcement can be a continuous or discontinuous. 3/18/2016 Squeeze casting 2
  3. 3. MANUFACTURING PROCESSES A] Continuously Reinforced Composites: - Vacuum Hot Pressing (VHP) B] Discontinuously Reinforced Composites: 1) Powder Metallurgy 2) Casting/ Liquid Metal Infiltration 3) Compocasting 4) Stir casting 5) Squeeze Casting or Pressure Infiltration 3/18/2016 Squeeze casting 3
  4. 4. BACKGROUND • Before understanding the mechanism of any processing method, it is necessary to take a prior knowledge of some concepts such as; 1) Interfaces (Wettability, Type of bonding, etc) 2) Preform Preparation 3) Infiltration Process 3/18/2016 Squeeze casting 4
  5. 5. PREFORM PREPARATION A. Adsorption and Wetting:  Good wettability is needed to generate a strong interface that will allow transfer and distribution of load from the matrix to the dispersed phase, without premature  Adsorption– It is a surface reaction which is dependent on concentration, temperature, and diffusivity. The greater the adsorption, the more the solute tends to lower the surface energy. B. Surface treatment of the reinforcement  The reinforcement surfaces are coated with suitable materials to improve wettability and adhesion and also to prevent any adverse chemical reactions at elevated temperature. 3/18/2016 Squeeze casting 5
  6. 6.  Example - 1. Coatings of SiC on boron fibre for Al matrices. 2. B4C coating on boron fibres for Titanium matrices. C. Matrix Modification:  It is done by modifying the matrix alloy composition.  Example- Alloying the Al matrix with Lithium promotes the wetting of polycrystalline Al2O3 fibres. The Lithium is believed to react with alumina to form a lithium aluminate which is more readily wetted by aluminium. 3/18/2016 Squeeze casting 6
  7. 7. INTRODUCTION TO SQUEEZE CASTING  Squeeze casting is the combination of the casting and forging processes that can be done with help of high pressure when it is applied during melt solidification.  It is a metal-forming process, which combines permanent mould casting with die forging into a single operation.  Referred by many names as “pressure infiltration”, “liquid metal forging”, ``extrusion casting”, “liquid pressing'', ``pressure crystallization”, ``squeeze forming”.  Employs low die filling velocity, with minimum turbulence and high applied pressure. 3/18/2016 Squeeze casting 7
  8. 8. PRINCIPLE • Applying pressure on the solidification of molten metal could change melting point of alloys which enhances the solidification rate. • Moreover it refines the micro and macrostructure; it is helpful to minimize the gas and shrinkage porosities of the castings. 3/18/2016 Squeeze casting 8
  9. 9. CLASSIFICATION Squeeze Casting Direct Squeeze Casting Without metal movement With metal movement Indirect Squeeze Casting 3/18/2016 Squeeze casting 9
  10. 10. DIRECT SQUEEZE CASTING  The pressure for the infiltration of the prefabricated preforms is applied directly to the melt.  The die is thereby part of the mold, which simplifies the structure of the tools substantially.  Disadvantage: - The volume of the melt must be determined exactly - The appearance of oxidation products formed in the cast part during dosage 3/18/2016 Squeeze casting 10
  11. 11. 3/18/2016 Squeeze casting 11
  12. 12. INDIRECT SQUEEZE CASTING  The metal is injected into the die cavity by a small diameter piston  Pressure is transmitted from the hydraulic source to the metal in a cavity through a runner system.  It is designed to combine the net shape advantage of high pressure die casting with the internal structural advantages of squeeze casting. 3/18/2016 Squeeze casting 12
  13. 13. 3/18/2016 Squeeze casting 13
  14. 14. Squeeze Casting Infiltration process has the following steps: • A preform of dispersed phase (particles, fibers) is placed into the lower fixed mold half. • A molten metal in a predetermined amount is poured into the lower mold half. • The upper movable mold half (ram) moves downwards and forces the liquid metal to infiltrate the preform. • The infiltrated material solidifies under the pressure. • The part is removed from the mold by means of the ejector pin. 3/18/2016 Squeeze casting 14
  15. 15. List of variables and parameters  Molten metal pouring temperature;  Melt volume;  Melt quality and quantity;  Preform preheating temperature;  Die temperature;  Applied squeeze pressure;  Pressurization rate;  Pressure applied duration; 3/18/2016 Squeeze casting 15
  16. 16. Theoretical background: Effect of pressure on solidification behaviour of alloy: • The application of pressure during solidification would be expected to affect phase relationships in an alloy system. This may be deduced by considering the Clausius-Clapeyron equation, where Tf is the equilibrium freezing temperature, Vl and Vs are the specific volumes of the liquid and solid, respectively, and ΔHf is the Latent heat of fusion. 3/18/2016 Squeeze casting 16
  17. 17. • Substituting the appropriate thermodynamic equation for volume, the effect of pressure on freezing point may roughly be estimated as follows: • where P0, ΔHf and R are constants. Therefore, Tf should increase with increasing pressure. 3/18/2016 Squeeze casting 17
  18. 18. SQUEEZE CASTING OF ALUMINUM METAL MATRIX COMPOSITES 3/18/2016 Squeeze casting 18
  19. 19.  Among all the MMC’s Aluminum metal matrix composites are finding increased applications, because of their improved mechanical and tribological properties.  Matrix- Aluminum metal and Reinforcement- SiC Particles  Parameters involved: 1) Squeeze Pressure: - Of the order of 100 MPa - Improves wettability and bonding force - Results in large undercooling and hence high nucleation rate- refinement change in structure. - A primary α (Al rich) phase seen as light dendritic areas and eutectic matrix of the α phase and silicon particles (darker areas) 3/18/2016 Squeeze casting 19
  20. 20. - Role: 1) the decrease of grain size 2) Decreasing SDAS 3) Reduction of porosity 4) increase in heat transfer coefficient 5) preventing Al4C3 6) Microstructural refinement, 10% increase in tensile strength 2) Casting (melt) / Preform preheat / Die temperature: - Best melt temperature is either 690°C or 660°C , at 630°C, the formation of very fine and uniform equiaxed grains. - SiC preform is preheated to 600°C- forms SiO2 layer - Die preheating temperature of 200°C-250°C, it shows increase in tensile strength and elongation. 3/18/2016 Squeeze casting 20
  21. 21. 3/18/2016 Squeeze casting 21
  22. 22. 3/18/2016 Squeeze casting 22 3) Solidification Rate: - Very high - The relation between the grain size “d” and the cooling rate “R” is written as: 𝑑𝑅 𝑎 =K where, K and d are constants. ‘a’ is factor which depends on type of composites. (0.34-0.39)
  23. 23. • Conclusions: - the grain size increased when the cooling rate decreased - The shorter the solidification time, the higher is the value of the property - The interface heat transfer coefficients were found to increase with the increase in applied pressure. 4) Reinforcement Particle Size: • When the particle size is smaller, the spacing between the particles is reduced. The smaller particles will exert more constraint on grain growth during cooling and more restriction on plastic flow during deformation, which can also contribute to increase in the strength. • Optimum reinforcement particle grain size of SiC in the range of 15-30 μm • The higher particle size which reduces the nucleation sites during the solidification and a weaker the bond strength which becomes the crack initiation sites in the composites. 3/18/2016 Squeeze casting 23
  24. 24. 5) Porosity and Mechanical properties: • The applied pressure increases the volume fraction of the Al-rich α-phase, and decreases in the size of the primary Al-rich dendrites. • High applied pressure finer microstructure increasing the freezing point increases nucleation frequency finer grain size structure low or no porosity • Increase in tensile properties, hardness, flexural strength 3/18/2016 Squeeze casting 24
  25. 25. CONCLUSIONS 1. The optimum pressure used in the squeeze casting of Aluminium alloys and composites, which gives a better microstructural refinement and increase in the mechanical properties, is 100 MPa. 2. The selection of the reinforcement particle size also influences the strength of the material in the squeeze casting process. The smaller the grain size the better the improvement in the properties. 3. The suggested melt and die temperature during the squeeze casting of Aluminium alloys and composites are 600°C to 700°C and around 250°C respectively. 4. There is a refinement in the microstructure with the combined effect of undercooling and a higher cooling rate, due to the high pressure level in the squeeze casting process. 5. The mechanical properties are enriched for both the alloys and the composites when fabricated through the squeeze casting technique, under controlled process parameters. 3/18/2016 Squeeze casting 25
  26. 26. ADVANTAGES Elimination of porosity and shrinkage 100% casting yield Attainment of greater part details Good surface finish, good dimensional accuracy High strength to weight ratio Improved wear resistance, higher corrosion resistance, resistance to high temperature Higher hardness Improved fatigue and better creep strength3/18/2016 Squeeze casting 26
  27. 27. DISADVANTAGES  Costs are very high due to complex tooling.  No flexibility as tooling is dedicated to specific components  Process needs to be accurately control which slows the cycle time down and increases process cost  High costs mean high production volumes are necessary to justify equipments investment. 3/18/2016 Squeeze casting 27
  28. 28. COMPARISON 3/18/2016 Squeeze casting 28
  29. 29. REFERENCES 1. M.R. Ghomashchi, A. Vikhrov, “Squeeze casting: an overview”, Journal of Materials Processing Technology 101 (2000) 1-9 2. M. Dhanashekara, V. S. Senthil Kumar, “Squeeze Casting of Aluminium Metal Matrix Composites- An Overview”, 12th global congress on manufacturing and management, GCMM 2014, procedia Engineering 97 ( 2014 ) 412 – 420 3. Krishnan K. Chawla, “ Composite Materials- Science and Engineering”, Springer Publication 4. T.R. Vijayaram, S. Sulaiman, A.M.S. Hamouda ∗, M.H.M. Ahmad, “Fabrication of fiber reinforced metal matrix composites by squeeze casting technology”, Journal of Materials Processing Technology 178 (2006) 34–38 3/18/2016 Squeeze casting 29
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