fluidized bed processes for production of metal alloys and ... · chemical vapor deposition in...

© 2013 SRI International

Fluidized bed processes for production of metal alloys and composites

Jordi Perez, Esperanza Alvarez, Fran Tanzella and Angel Sanjurjo

SRI International

Titanium USA 2015, Orlando FL, Oct 5th 2015


Who We AreSRI is a world-leading R&D organization

• An independent, nonprofit corporation founded by Stanford University in 1946• $4 billion in sponsored R&D in the last decade• $540 million in annual revenue• 4,000 issued patents• 2,100 employees worldwide• 69 years of contributions to society• 60 spin-off companies• 20 locations• 1 mission: World-changing solutions to make people safer, healthier, and more productive.

Princeton, New JerseySilicon Valley - Headquarters Harrisonburg, Virginia

Tokyo, Japan

Washington, D.C.

State College, PennsylvaniaSt. Petersburg, Florida Arecibo, Puerto Rico


Chemical Vapor Deposition in Fluidized Bed Reactors

3

Combination of 2 technologies extensively used in industry

CVD– Tools– Semiconductor industry– Solar cells– Decoration– …

FBR– Petrochemical– Polymer – Nuclear– Surface treatments– …

+

FBR-CVD allows gas-solid chemical processes to form new materials taking advantage of the excellent heat and mass transfer of fluidized beds: homogeneous deposition, lower temperatures and higher deposition rates than conventional CVD.


Applications of FBR-CVD for coatings, thin films…

4

0

5

10

15

20

25

30

0 200 400 600 800 1000

displacement / nm

H /

GPa

TiSiN (9 Si at%)

SiNx

TiN

TiN/W

TiN/TaN

• Diffusion coatings– Corrosion protection of steel– Cr, Si,…

• Ceramic thin films– TiN, Si3N4, SiO2,…

• Composite films– Metal-ceramic multilayers– Ceramic-ceramic nanocomposites

• Coating porous structures– Filters for coal gasifier

• Thin films for solar cells– C-Si films

Si on steel

EDX depth profile

Uncoated steel TiN/steel GD-OES depth profile

nanoindentation

TiN/SiNx

TiAlN/Nb

Filter cross-section

TiAlN/Nb film

Film cross-section

Top view, textured filmP doping


…for particle modification and production of metals

5

Full encapsulation• Corrosion protection• Appearance• Electrical properties

Deposition of islands• Catalysts

Molybdenum• MoCl5 + H2• 70% single pass yield in

preliminary runs• 39 ton·m-2·year-1

Vanadium production• VCl4 + H2

• W interlayers


Thermochemical data

6

Gibbs free energy of formation of several metal chlorides per mol of Cl2 (analogous to Ellingham diagram for oxide stability)• Reduction reaction MClx + (x/2) H2 = M + x HCl is favored at high T because of entropy

contribution to ΔH − TΔS• Chlorides above dashed H2 line can be reduced directly by H2

• For chlorides below dashed H2 line, direct reduction is not possible


Thermochemical data - Ti

7

• Measurements: high T equilibria in the Ti-H-Cl system [1]: – new standard enthalpies of formation of TiCl, TiCl2, and TiCl3– Above 1200 K, P[TiCl3] is about an order of magnitude higher than P[TiCl4]

• Model prediction: – with H2 present, Ti deposited at T>1100 K– higher H2 concentrations result in higher conversion to Ti

Temperature (K)700 900 1100 1300 1500

Partial

Press

ure (at

m)

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

TiCl

TiCl2

TiCl4

TiCl3Ar/TiCl4/Ti = 1/0.1/10Total Pressure = 1 atm

Temperature (K)

900 1100 1300 1500 1700 1900 2100

Mole

10-4

10-3

10-2

TiCl2(c)

Ti(c)

H/TiCl3 = 10/0.01

H/TiCl3 = 1.5/0.01

Ti(c)

Ti(c)

H/TiCl4 = 4/0.01

TITANIUM FORMATION AT VARIOUS H/TiClX RATIOSNOVEL THERMOCHEMISTRY DETERMINED BY SRI

[1] D.L. Hildenbrand et al., High Temp. Mater. Sci., 35 (1996) 151


Ti production in fluidized bed

8

• Thermal reduction of TiCl4 by H2

• Ti deposition shown in multiple runs at lab scale• Direct production of alloys demonstrated by simultaneous reduction of TiCl4 and VCl4• Limitation during scale-up related to particle aggregation at high temperature

TiCl4/VCl4 molar ratio Film Composition (wt%)

0.8 19 (Ti) / 81 (V)

13.1 75 (Ti) / 24 (V)

36.7 90 (Ti) / 10 (V)

87.3 97 (Ti) / 3 (V)


Direct production of advanced alloys is possible

9

• A shell composed of titanium silicides was formed on Si seed particles by treating them with TiCl4 in a fluidized bed (red arrow on phase diagram).

• The process could be continued to fully convert Si particles.• If a C source was also present, the desired Ti3SiC2 phase could be formed

(blue arrow in phase diagram)

An example: MAX phases• High temperature wear, corrosion resistance, and toughness• Electrically and thermally conductive • Stiff but they can be machined as easily as metals


A step forward: adding electrical arcs to FBR-CVD

Destruction of organic molecules using MAFBR

Multi-arc fluidized bed reactor (MAFBR)• Atmospheric pressure

– Low cost• Plasma-like environment

– High reactivity

Applications include:• Destruction of contaminants• Deposition of coatings• Synthesis of materials

© 2013 SRI International 11

• Production of granules that are ready to use in powder metallurgy (particle sizes from 10s of microns to mm)

• Use of atomic hydrogen as reducing agent

• Direct production of alloys• Applicable to other metals, ceramics…

MAFBR in operation with Ti alloy particles

ARPA-E METALS: direct production of Ti alloys in MAFBR


MAFBR- Experimental setup

12

Quartz reactors with porous disk as gas distributor, lateral ports for thermocouple, electrodes and TiCl4 injector.

H2–containing gas pre-heated using resistive furnaces

Electrical arcs: ΔV between top and bottom electrodes.

TiCl4 was supplied into the system using a standard bubbler.


MAFBR- Proof-of-concept tests with alumina seeds

13

First tests with alumina seeds:• Visual assessment• Easy chemical analysis (XRF)

Untreated alumina (left) and alumina after Ti deposition in the MAFBR

But…Limitations of low temperature:• TiCl2 solid can be hard to reduce


Starting material

Run 16327-122(V deposition)

Run 16327-123(V-Ti co-deposition)

wt% Al 1.2 0.5 0.5wt% Ti 97.0 83.7 85.2wt% V 1.8 15.8 14.3

MAFBR- Ti:V co-deposition

• Bed temperature ~ 700 °C

• Seeds: Ti6Al4V 400-500 microns

• Reactant mixture: H2, TiCl4, VCl4• Particles had metallic appearance

• No Cl detected by XRF

• Mass gain, but low yield

• Higher mass gain in V-only run

• Alloy production took place, but competing

etching mechanism (back-reaction with HCl)

14

Surface of particles after V run

Surface of particles after Ti:V run

Surface of original seeds

© 2013 SRI International 15

Multiple-zone reactor

SEM of original seeds SEM of particles after run SEM of particles after run

• Particles circulate between zones at different temperatures

• Low-T zones for partial reduction of TiCl4• High-T zones to increase partial pressure of

subchlorides• Subchlorides recovered in low-T zones• Mass gain found in short preliminary runs• Single pass yield >60% (non-optimized)• Energy consumption ~ 60 kWh/kg Ti


MAFBR- Low temperature partial reduction

16

• Partial reduction of TiCl4 takes place at very low temperature (500 °C) due to activation of reactants

• Combination of arcs, H2 and Ti in the bed are needed

• Resulting solids are dark and hygroscopic• Mass balance included water wash and Cl- ion

measurements:• 35% of incoming TiCl4 was reduced to Ti• 54% of incoming TiCl4 was reduced to TiClx

• Reduction to Ti can be finished electrochemically

SEM of particles after run

Run Ti bed Arcs H2Ti subchlorides

16242-114 NO YES YES NO

16242-115 YES NO YES NO

16242-116 YES YES NO Very small

16242-107 YES YES YES YES

Before After


MAFBR- Low T partial reduction + electrowinning

17

Proof-of-concept test:• Product from low-T MAFBR partial reduction

transferred into electrochemical cell• Electrodes: graphite• Electrolyte: LiCl+KCl• T = 650 °C• Recovery of products by washing with water (O

content in recovered powders is artificially high)• Using 1” MAFBR reactor, 2.5 g of Ti were produced

in 1 hour• Based on preliminary data we estimate that Ti can

be produced by MAFBR+ electrowinning with energy consumption <55 kWh/kg_Ti (including energy to produce reactants)

• Development of a system to transfer TiClx from MAFBR to electrowinning steps is needed

Electrode configuration

Voltage and current during test


New applications for synthesis of materials in FBs

18

NANOSTRUCTURED POWDERSNanometer-size layers easily formed by FBR-CVD (example: W nano-layer in a V particle)

• Powders with multiple metal layers can be produced.

• Ceramic inclusions in metal alloys are possible.

METAL-CERAMIC NANOCOMPOSITES

Infiltration of porous ceramic powders (i.e. alumina) with metals.

• Controlled composition• Controlled micro /

nanostructure

INFILTRATION OF TITANIUM SPONGE

Deposition of metals such as V, Al, B, W, Nb… on Ti sponge:

• Oxygen content in sponge can be lowered

• Products are ready for PM, 3D-printing…

• Successful first tests

wt% Ti wt% V wt% W

Run A 96.8 2.0 1.2

Run B 90.2 8.4 1.3

IMPACT• Scalable production of feedstock for 3D-printing, laser sintering, powder metallurgy,…• Materials with better mechanical properties at high temperatures• Lightweight alloys and composites with high strength


Aknowledgements

19

• SRI team: Esperanza Alvarez, Fran Tanzella, Angel Sanjurjo, Chia-Pin Pan, JianEr Bao, Anoop Nagar, Kai-Hung Lau, Marc Hornbostel, Gopala Krishnan

• Collaborators:– Eugene Thiers– James Withers

• Funding: – ARPA-E (DE-AR0000460)*– DARPA

Contact: Jordi Perez, [email protected]

* The information, data or work presented herein was funded in part by the Advanced Research Projects Agency-energy (ARPA-E), U.S. Department of Energy under Award Number DE-AR0000460

fluidized bed processes for production of metal alloys and ... · chemical vapor deposition in...

Documents