What you should know about FGM Sirris Materials day 2013

Introduction Principle & description History Applications Manufacturing methods Pros and cons Conclusions

Principle & description A Functionally Graded Material (FGM) is a substance in which properties,

composition and/or structure is not homogenous. There is a controlled spatial distribution of these characteristics to optimize the part made of this FGM.

Example with a turbine blade :

Erosion & heat

weight

Pressure &

vibration

=> Ceramic on the

external surface

=> Metal matrix

=> Light weighted core

Principle & description FGM is composite 2.0 :

Composite Sharp interface Risk of delaminating Weakness and strength

everywhere

FGM Smooth transition Very good bond Volume properties

distribution material adaptation for

specific application.

The whole part is a bit ductile and a bit hard, homogenously

This region is largely hard

This region is largely ductile

History : FGM in Nature :

Bamboo fibre reinforced biocomposites: A review - H.P.S. Abdul Khalil, I.U.H. Bhat, M.Jawaid, A. Zaidon, D. Hermawan, Y.S. Hadi - Materials & Design - Volume 42,

December 2012, Pages 353–368

http://www.britannica.com

First human FGM in 1985. challenge : 1000°C temperature gradient over a thickness of only 10 mm :

700°C

10 mm

History :

1700°C

Outside Inside

http://en.wikipedia.org/wiki/Functionally_graded_material

Cutting tool : Mitsubishi Carbide developed “Miracle Coated

Indexable Inserts” : carbide substrate

Applications :

http://www.mitsubishicarbide.com/mmc/en/product/pdf/b/b031g.pdf

Applications Architecture :

Applications Ballistic

http://www3.ntu.edu.sg

Applications : Articulated mechanical parts :

Biomimesis in Standford

Applications : Thermal choc resistant for thermal barrier FGM:

Applications : Tailored thermal conductivity property for thermal management :

Heat removal in engine bloc Cooling of electrical components

Definition of a ceramic (alumina foam)/metal (aluminum) gradient. The ceramic is an insulator which protects cold devices from heat and aluminum drives heat away from hot devices

Applications : Graded porosity of bones implants for better bone re-

colonization :

Applications : Graded porosity for adapted mechanical behavior :

Applications : Functionally graded implants :

http://research.unt.edu/ises/advanced-metallic-materials

Applications : Constant dielectric characteristic over temperature:

5 layers/compositions => ~composite

21 layers/compositions, same thickness => FGM

21 layers/compositions, variable thickness

http://144.206.159.178/ft/677/43119/781575.pdf

Applications : Thermal dilatation in High-Intensity Discharge lamp :

http://www.toto.co.jp/E_Cera/lampparts/fgm_electrode.htm

Applications : Reduced electrical field stresses in power supply insulators :

Δ = 100 kV

uniform

FGM

http://ir.nul.nagoya-u.ac.jp/jspui/bitstream/2237/14528/1/1097.pdf

Applications Buffer section between 2 different materials :

Material distribution in the FGM layer

Applications : Manufacturing of an ablation resistant SiC/C FGM:

Higher

number of layers is

better for residual thermal stresses

Linear evolution is better for residual thermal stresses

Processing methods Classification :

Homogenizing Segregating Constitutive

Processing methods – powder metallurgy Formation of graded powder compact (green) : Stepwise change : Die compaction (powder stacking) Limited N° of layers (< 10, 1mm/layer) Discontinuous process Low productivity

Processing methods – powder metallurgy Formation of graded powder compact (green) : Stepwise change : Sheet lamination Complex shapes achievable Sheets are expansive (powder rolling or

tape casting -> “green” state) Assembly by hot pressing

Processing methods – powder metallurgy Formation of graded powder compact (green) : Stepwise change : Wet powder spraying : Coating on complex surface Layer thickness from 50 µm -> ~1 mm

Processing methods – powder metallurgy Formation of graded powder compact (green) : Stepwise change : Slurry dipping : Thin coating by dipping in different

baths. Suitable for series production. Enter porous body by capillarity.

Processing methods – powder metallurgy Formation of graded powder compact (green) : Stepwise change : Solid freeform processes : Hot powder-binder mixtures extruded in

a mixing nozzle.

Processing methods – powder metallurgy Formation of graded powder compact (green) : Continuous change : Gravity sedimentation: Material choice limited Inter-particles interaction in highly

loaded suspensions Simple and repeatable

Processing methods – powder metallurgy Formation of graded powder compact (green) : Continuous change : Electrophoretic deposition: Continuous change of suspensions Different electrophoretic mobility Risk of bubble entrapment Several mm thick

Processing methods – powder metallurgy Formation of graded powder compact (green) Continuous change : Thermal spraying : Gradient coating on existing parts “Mechanical” bond

Processing methods – powder metallurgy Melting processes : Laser/plasma cladding : Gradient coating on existing parts.

Inconel 718 -> SS 316L

Pure SS 316L

SS 316L -> Inconel 718

Pure Inconel 718

SIRRIS

Processing methods – powder metallurgy Melting processes : Centrifugal/sedimentation casting : Solubility or wetting problems

Review Fabrication of Functionally Graded Materialsunder a Centrifugal Force Yoshimi Watanabe and Hisashi Sato

Processing methods – powder metallurgy Melting processes : Controlled mold filling : FGM width controlled by the degree of

solidification of the first melt

Processing methods – powder metallurgy Melting processes : Infiltration processing : Preform (metallic foam, pre-sintered green

part,…) with porosity gradient Infiltration by lower melting component Open pores/wetting needed

Processing methods summary

Processing techniques for functionally graded materials - B. Kieback, A. Neubrand, H. Riedel – materials science & engineering A - 2002

Software developments New file format to develop the famous “.stl”, with

its own standard : ASTM F2915-12 “AMF” stands for “Additive Manufacturing Format” XML script Open source Volume capabilities for FGM or lattices

A lot of characteristics can be selected for each voxel such as color, texture, material, density,…

http://amf.wikispaces.com/ http://www.astm.org/Standards/F2915.htm

Software developments Another FGM software from the MIT : Spec2Fab

http://spec2fab.mit.edu/

Pros

Solution for incompatible materials combinations

Improve materials efficiency Increase part lifetime

Cons

Processes hard to control Complex phenomenon occur

(shrinkage, dilution, distortions,…)

Expansive techniques

Pros and Cons :

Conclusions FGM = composite 2.0 More efficient use of materials capabilities Already in the industry Applicable in every technological fields.

=> Thank you for your attention !