overview of cold spray - sandia national laboratories · pdf file 2007-08-27 · mfs...

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  • MFS CSO 90714

    Dr. Mark F. Smith Cold Spray Workshop

    Albuquerque, NM July 14-15, 1999

    Overview of Cold Spray

    Particle Velocity (m/s)

    > 325

    > 350

    > 375

    > 400

    > 450

    > 475

    > 500

    > 425

    2000 100 300 400 500

    G as

    P re

    ss u

    re (

    p si

    g )

    200

    250

    300

    350

    400

    Gas Temperature (ˆC)

    Air, 22 µm Copper

    100 µm

  • MFS CSO 90714

    250 m/s Cu

    A “Cold” Process Technology from Siberia

    900 m/s Cu

    Deposition Efficiency

    Copper Coating Material

    Iron Nickel Aluminum

    After Alkimov, et al , 1990

    400 500 600 700 800 900 1,000

    0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1

    0

    Particle Velocity m/s

  • MFS CSO 90714

    Sandia Cold Spray System

    HEATED GAS Gas Inlets

    Heater

    TC

    Gas Heater

    Powder Feed

    Robot Manipulator

  • MFS CSO 90714

    Spray Ductile Metals, Cermets, Polymers

    Active Braze Alloy Aluminum Aluminum Bronze Copper 304 Stainless Steel 420 Stainless Steel

    Fe3Pt Molybdenum Monel 80Ni/20Cr NiCrAlY NiCr-Cr3C2

    Polymer StelCar Tantalum Tin Titanium WC-Co (nanophase)

    Examples of Materials Successfully Deposited at Sandia

  • MFS CSO 90714

    Cold Spray vs. Air Plasma Spray

    Plasma Sprayed Copper

    Cold Sprayed Copper

    100 µm

    100 µm

    • Superior Density • Less Oxide

  • MFS CSO 90714

    Some Exciting New Possibilities

    • Avoid melting & solidification - Avoid thermally induced stress - Avoid undesirable phases - Avoid oxidation (deposit metals in ambient air!) - Preserve desired phases & chemistry - Preserve original grain size (nanocrystalline mat’ls)

    • Low Porosity (>99% dense, as deposited) • High thermal / electrical conductivity (>80% OFHC Cu)

    • High Deposition Efficiencies (>98%)

    • Recycle feedstock & process gas • Work with highly dissimilar materials combinations

  • MFS CSO 90714

    New Possibilities, cont’d.

    • Highly wrought material (high hardness / strength)

    • Potential for high deposition rates • Relatively insensitive to standoff, work up close (

  • MFS CSO 90714

    Cold Spray Direct Fabrication

    • Additively build net / near-net shapes directly from a computer

    • Key technical challenge is focussing the spray stream

    ~ 1 mm Focused Stream for

    Subsonic Flow

    Do you want a print or a part? Print Build OK

    OK

    Do you want a Print or a Part? Print Build

  • MFS CSO 90714

    Example Applications

    • Anti-corrosion (superior density, less oxide)

    • Wear resistance (superior hardness & density)

    • Metals on ceramics / glass

    • High-alloy / specialty metals (preserve composition & phases)

    • Plastic coatings without volatile organics

    • Defect repair (minimal masking / heating, machinable)

    • Direct fabrication

    • Satellite structures (high conductivity, low residual stress)

  • MFS CSO 90714

    Reclaiming Parts & $$$

    Unusable $150k GPS satellite part reclaimed

    with Cold Spray

    • Low heat input • Low stress • Dense, machinable • High conductivity,

  • MFS CSO 90714

    State of the Art

    • Technology ~ 10 years old • Success with many metals, some cermets & polymers • New materials / processing / manufacturing possibilities • Considerable industrial interest • Patented, but licenses available • No commercial use yet

  • MFS CSO 90714

    Barriers to Commercial Use

    Technical Issues:

    • Process fundamentals poorly understood • Cannot predict materials / parameters • Reduce / eliminate expensive helium • Nozzle fouling / optimization

    Build-up in nozzle

  • MFS CSO 90714

    Barriers to Commercial Use

    Manufacturing Issues:

    • No commercial equipment / coating suppliers • Need articulated robot compatible spray gun • Lack of property data / field experience • Need better fine powder feeders

    Uneven deposition due to uneven powder feed

  • MFS CSO 90714

    Understanding Critical Velocity

    Raw Particle Velocity Distributions

    0

    20

    40

    60

    80

    100

    200 400 600 800 1000 1200

    0 % 53 % 95 %

    N o

    rm al

    iz ed

    C o

    u n

    ts

    Particle Velocity (m/s)

    Deposition Efficiency

    1 2 3

    19 µm Copper powder onto Aluminum

    0

    20

    40

    60

    80

    100

    450 500 550 600 650 700 750 800

    D ep

    o si

    ti o

    n E

    ff ic

    ie n

    cy (

    % )

    Mean Particle Velocity (m/s)

    3

    2

    11

    2

    3Experiment Prediction

  • MFS CSO 90714

    Process Maps Guide Optimization

    Particle Velocity (m/s)

    > 325

    > 350

    > 375

    > 400

    > 450

    > 475

    > 500

    > 425

    2000 100 300 400 500

    G as

    P re

    ss u

    re (

    p si

    g )

    200

    250

    300

    350

    400

    *DV�7HPSHUDWXUH��Û&�

    Air, 22 µm Copper

  • MFS CSO 90714

    Models Guide Nozzle Design

    dD dP

    = CD Ap M 2

    2 − 1

     

     

    dVp dt

    = D m

    Vp = particle Velocity D = Drag force m = particle Mass P = Pr essure

    CD = Drag coefficient Ap = Area of particle M = Mach number

    max @ M = 2 = 1.4

    (air)

    (helium)

    A*/A = Choke Point/Nozzle Exit Area Ratio (Axial Position measured from choke point)

  • MFS CSO 90714

    “Estimator” ver. 1.0 for Spray Parameters

    Air Helium

  • MFS CSO 90714

    Understanding Particle Impact

    1 km Asteroid Impacting Ocean 300 Gigatons TNT Equivalent (10x Peak of All Cold War Nuke’s)

    Sandia Teraflops computer running CTH code 100 million computational cells 18 hr @ 91% capacity (8,192 of 9,000 processors)

  • MFS CSO 90714

    Computational Impact Model & Experimental Comparison

    Predicted peak temp. of 1280 K is below the

    melting point of Cu (1357 k)

    Cu

    Stainless Steel 25 µm

    4

    3

    2

    1

    0

    - 1

    - 2

    - 3

    - 4

    Cu

    Stainless Steel

    t = 70 nst = 70 ns

    X (microns) - 4 - 2 0 2 4

    Y (

    m ic

    ro n

    s)

    Copper

    Steel

    Void

    Temperature K

    980

    900

    810

    720

    630

    540

    450

    380

    25 µm Cu Sphere into 304 Stainless at 600 m/s

  • MFS CSO 90714

    Summary

    • New materials / processing / manufacturing possibilities • Opportunity to be first to exploit market advantage • Several pre-competitive barriers need to be solved • Faster / cheaper / better to work together on pre-comp. • Partners will gain access to best technology & new IP