Digital Material
Deposition for Product
Manufacturing Processes
Purpose of Presentation

Provide an overview of how the
digital printing technologies utilized in
the reprographics industry for over 50
years have been used for:

Unusual printing applications

Special material deposition
applications
Material Deposition Presentation
2
What is Digital Material
Deposition?


The preparation of materials to make them
suitable for digital deposition
The means (process, hardware, and controls)
to enable the controlled lay-down of materials
onto various substrates:


Practiced in the reprographics industry for over 50 years
as copying & printing
Processes and technologies have now been applied to a
wide variety of non-printing applications
Material Deposition Presentation
3
Applications of Digital
Deposition

The technologies of digital printing are
being used to:






Make products
Print on products
Coat products
Print on product containers
Print on packaging
Print labels
Material Deposition Presentation
4
Advantages of Digital
Deposition

Precise & controlled amounts of material lay-down



Selectively variable process




Little to no material wastage
Readily scalable




Change amounts and placement at will
Create images - monochrome to full color
Layered construction
High value material capability


Mass
Thickness
From laboratory, to pilot, to production
Short-run to long-run
Narrow to wide format
3-Dimensional applications
Material Deposition Presentation
5
Potential Disadvantages of
Digital Deposition Technology



Some systems can be complex
Sometimes material latitudes are limited
May be more costly on a cost per unit basis
than long-run conventional processes



Offset
Blade coating
Pad printing
Material Deposition Presentation
6
The Primary Forms of
Deposition Materials

Deposition Materials can be :



Liquid materials
or
Dry powder materials
or
Dry film materials
Material Deposition Presentation
7
Widely Practiced Reprographic
Deposition (Printing) Systems

Electrostatic (Dry powder and liquid)



Electrophotography
Electrography
Inkjet (Liquid)

Drop on Demand



Continuous
Thermal (Dry film)


Thermal & Piezoelectric
Direct & Transfer
Magnetographic (Dry powder)
Material Deposition Presentation
8
Digital Deposition Processes
Overview
Digital Deposition Processes
Latent Image
Intermediate
Direct-toReceiver
Special Process
Receiver Media
Electrophotography
Drop on Demand IJ
Dry Silver
Ionography
Continuous IJ
Thermal Paper
Electrography
Thermal Transfer
Electrostatographic
Magnetography
Toner Jet
UV Light Sensitive
Material Deposition Presentation
9
Major Segmentation of
Deposition Technologies

Deposition system


Direct versus Indirect
Material properties

Liquid versus Dry
Material Deposition Presentation
10
Major Segmentation Map
Direct Process
Inkjet
 Electrostatic

Liquid
Indirect Process

Electrostatic
Electrophotography
Electrography
Electrophotography
Electrography

Dry

Electrostatic

Electrostatic
Electrophotography
Electrophotography
Electrography
Electrography
Thermal Transfer
Magnetographic
 Solid Inkjet

Material Deposition Presentation
11
Liquid vs. Dry

Conventional thinking for dispensing, dosing,
metering:

Liquid deposition via inkjet technology
 The

‘de facto approach’
However, liquid AND dry powder materials can
be digitally deposited

Highly application dependent
Material Deposition Presentation
12
Liquid Deposition &
Micro-dispensing
Material Deposition Presentation
13
Printhead Roadmap
Continuous
Multiple
Deflection
Single Jet
Multi-Jet
Binary
Deflection
Hertz
Mist
Drop-on-Demand
Piezoelectric
Thermal
Electrostatic
Hollow
Tube
Edge shooter
Bending
Plate
Roof shooter
Acoustic
Extending
Member
Shear
Mode
Magnetic
Deflection
Material Deposition Presentation
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Inkjet Implementation:
Fluid Issues
Fluid physical attributes and chemistry drive
the system design:
•
•
•
•
•
•
•
•
•
Aqueous or non-aqueous
Chemically reactive with print head
Viscosity versus temperature
Surface tension
pH
Volatility
Fluid temperature constraints
Fluid formulation modification latitude
Particulate size
Material Deposition Presentation
15
Inkjet Implementation:
Head Issues


All inkjet head types are possible candidates
Head matched to the fluid and application:







Ejected volume and nozzle count requirements
Jetting frequency requirement
Throw distance and direction
Number of unique fluid types required
Head maintenance algorithms and hardware
Ambient environment
Reliability and operator interaction constraints
Material Deposition Presentation
16
Inkjet Implementation:
Substrate Issues

Like the fluid, the substrate is typically a given and
influences the integration:

x and y motion requirements




Speed, step size, and precision
Mounting and alignment
Topography considerations
Substrate - Fluid interactions
Material Deposition Presentation
17
Inkjet Implementation:
Other Challenges



Head-drive electronics and algorithms
Data source and manipulation requirements
Environmental concerns




Temperature and humidity
Outside contaminants
Process effluents
Drying
Material Deposition Presentation
18
Example:
Polymer Electronics - Displays
Ejection of electro-luminescent polymer onto
glass substrate for monochrome or color
displays
ADVANTAGE
•
•
•
•
Inexpensive
Automated
Repeatable
“Displays-onDemand”
Example:
Polymer Electronics - Sensors
Ejection of “environmentally sensitive” polymer
onto silicon or advanced PCB substrate
ADVANTAGE
• Inexpensive
• Automated
• Repeatable
• “Sensors-onDemand”
Example:
Rapid Prototyping – SLA Substitute
Layer-upon-layer fluid ejection to
build computer-generated, threedimensional parts and
prototypes.
ADVANTAGE
•
•
•
•
Inexpensive
Automated
Repeatable
“Parts-on-Demand”
Material Deposition Presentation
21
Manufacturing Dispensing
Examples
Flexible adhesive placement, coating,
soldering, and precise patterning for
in-line and off-line production
ADVANTAGE
• Automated
• Repeatable
• Quantity-controlled dispensing
Material Deposition Presentation
22
Example:
Manufacturing – Dispensing Solder
25µm bumps of
63/37 solder
deposited on 35µm
pitch using “Solder
Jet” technology
Material Deposition Presentation
23
Example:
Pharmaceutical – Dispense Active
Agent

Advanced drug-dispensing system

Active agent(s) stored in carrier wells that
are filled on demand by specialized inkjet
heads
ADVANTAGE


Increased medical control over drug
application
Drugs tailored to individual’s medical
requirements
Example:
Biotechnology – DNA Testing


HP partnership with Affymetrix Gene Chip
Dispensing of “tiny DNA segments, housed
inside picoliter-size droplets of liquid … onto
an array of integrated circuit-like chips…”
Source: Upside, Sept. 23, 1998 (www.upside.com)


ADVANTAGE
Automated procedures
Repeatable results
Example: Medical - Containment
Hydrophobic material forms barrier to contain
biological fluids or other fluids for tissue
preparation
ADVANTAGE
• Automated
• Pattern retention
• Repeatable processes
A Case Study – Liquid Deposition
Precision coating of a medical device for drug
loading
 Project performed by Xactiv Inc, www.xactiv.com
(formerly Torrey Pines Research)
 The development activity was carried out on behalf
of a client

Material Deposition Presentation
27
Case Study – Stent Coating

Stent – small, lattice-shaped, metal tube that is
inserted permanently into an artery. The stent
helps hold open an artery so that blood can flow
through it.
Material Deposition Presentation
28
Case Study – Stent Coating
Requirements






Drug eluting stent is coated with polymer that
incorporates a drug that helps prevent plaque buildup
Drug elutes very slowly over a period of years
Coating must be applied uniformly on inside and
outside of stent
Coating thickness must be very uniform (+/- 5%)
Coating weight stent to stent must be well
controlled (+/- 5%)
Stents of various diameters and lengths
Material Deposition Presentation
29
Case Study – Stent Coating Challenges

Coating materials pre-defined by client





Polymer has few viable solvents
Stent must be coated all over while handling
Precision requirement
Minimize wastage
Speed
Material Deposition Presentation
30
Case Study – Stent Coating
Solution


Piezo industrial drop on demand system
selected
Dimatix S-series print head
Resistant to solvents
 Precision jetting system


TPR modified the print head

Replaced seals
Material Deposition Presentation
31
Case Study – Stent Coating Solution

Piezo drop on demand industrial print head




Custom designed stent handling system
Custom designed precision inkjet coating system
Special maintenance algorithms and maintenance
system




Modified seals to withstand solvent
Eliminate nozzle blockage due to drying
Solvent resistant fluid handling
Solvent chemistry
Ink development
Material Deposition Presentation
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Case Study – Stent Coating

Precision stent handling system
Material Deposition Presentation
33
Case Study – Stent Coating

Precision inkjet coating system
Material Deposition Presentation
34
Case Study – Stent Coating System
Material Deposition Presentation
35
Dry Powder
Deposition
Material Deposition Presentation
36
Electrostatic Dry Powder Deposition
Typical Application Requirements

Dry powder materials



Solvent-less process
High area coverage - usually







From ~ 5 to 75 microns in size
Large volumes of material
Precise metering/thickness control
Uniform coating
Static or variable information
Contact or non-contact process
Direct or indirect process
2D or 3D deposition
Material Deposition Presentation
37
Conventional Powder Coating
Charging air gun
Typical powder
spray system
Material Deposition Presentation
38
Conventional Powder Coating
Problems/Limitations

Corona or tribo charging with air transport
 Poor
powder charging
 Poor directional control
 Air overwhelms electric field and wastes material
• Requires substantial post “clean-up”
Uniformity not assured
 Masking difficult
 Images with information impossible

Material Deposition Presentation
39
The Challenges of Electrostatic
Powder Development

Using/modifying or creating the materials for:
Functional requirements of application
 Charging
 Transport


Identifying a suitable powder Development
Sub-system technology


Direct versus Indirect architecture
Dealing with Substrate properties

Often a given
Material Deposition Presentation
40
Important Powder Properties

Dielectric properties







Insulative versus conductive
Magnetic properties
Powder size and size distribution
Electrostatic charging
characteristics
Rheological (melt) properties
Flow properties
Functional characteristics
Color
 Application dependent functionality

Material Deposition Presentation
41
Important Substrate Properties

Dielectric properties


Insulative versus conductive
Flat or 3D

If flat
 Sheet
vs. roll stock
 Flatness tolerance

If 3D
 Shape


and 3D depth
Layered construction characteristics
Hard vs. soft characteristics
Material Deposition Presentation
42
Dry Powder Deposition System
Considerations
Powder Properties
Conductive
Insulative
Magnetic
Non-magnetic
Charging Method
Triboelectrification
Induction
Substrate Properties
Deposition Method
Direct
Conductive
Insulative
Transfer
Material Deposition Presentation
43
What are Conductive Materials

It depends on time for current to flow:
With copper – not very long
 With fused quartz - sit down because you’re
going to be there a while


Conductivity represents a continuum
Material Deposition Presentation
44
Conductivity is a Continuum
Conductive
Materials




Semi-conductive
Materials
Insulative
Materials
In conductors, electric charges are free to move
In an insulator, charges are less free to move
There’s no such thing as a perfect insulator
25
 However, insulating ability of fused quartz is 10
times that of copper
Conductivity is characterized by a physical property
- Resistivity
Material Deposition Presentation
45
Resistivity of a ‘Conductive’ Material
A conductive material for many electrostatic processes may
have a resistivity of 7.5(108) ohm-cm or less.
Resistivity Scale (ohm-cm)
0 – 10-8
Most Metals
108
Conductive
Materials
1018
Fused Quartz
1010
??
Insulative
Materials
Material Deposition Presentation
46
The Significant Properties that
Drive the Electrostatic Deposition
Process

Powder charging


Determined by the material being Conductive
versus Insulative
Powder transport

Determined by the material being Magnetic
versus Non-magnetic
Material Deposition Presentation
47
Charging of Insulative Powders

Insulative Material Charging

Most commonly charged by
triboelectrification

Mechanical contact/rubbing causes
charges to exchange
-- -+
+
+
-- -+-
-- -+
- +
-- -+
+
+
+
- +
+
-- +
+
-- -+ +
-
Functional Powder
Carrier
Material Deposition Presentation
48
Triboelectric Series
Air
Human Hands
Asbestos
Rabbit Fur
Glass
Mica
Human Hair
Nylon
Wool
Fur
Lead
Silk
Aluminum
Paper
COTTON – The Dividing Point
Steel, Wood
Amber, Sealing Wax
Hard Rubber, Nickel, Copper
Grass, Silver, Gold Platinum
Sulfur, Acetate, Rayon
Polyester, Celluloid
Orlon, Saran
Polyurethane, Polyethylene
Polypropylene, PVC (Vinyl)
Kel-F (CTFE)
Silicon
Teflon
Material Deposition Presentation
49
VOLUME (Number)
Powder Charge Distribution
-5
5
10
15
20
25
30
Charge - C/gm
Wrong
Sign
Low
Charge
Target
High
Charge
Material Deposition Presentation
50
Charging of Conductive Powders

Conductive Materials

Most commonly charged by Induction

An applied voltage causes electrons to
migrate to the tip of the material in the
presence of an electric field (E)
---
+
_
V
Material Deposition Presentation
51
Powder Transport
Magnetically permeable powders are most
commonly transported via magnetic forces

Powder can be magnetically permeable
or
Can incorporate a magnetic Carrier
S
N
Development
Zone
N
S
S
Substrate
N
N

S

Material Deposition Presentation
52
What about the Substrate?

The substrate is the material upon which the powder is
being deposited.


It ultimately refers to the final working material for the given
application.
Examples might include:

Electronic materials








Flexible circuits
PCB materials
Pharmaceutical tablet
Consumer products
Product packaging
Food products
The substrate can be conductive or insulative
Its properties will dictate the powder and transfer method
Material Deposition Presentation
53
Electrostatic Deposition Material
Choices
Powders
Insul
Cond
Insul
Yes
Yes
Cond
Yes
Yes
Substrate
The physics to follow
Material Deposition Presentation
54
Dry Powder Development
• Purpose
• Apply powder particles to the electrostatic latent
image on the photoreceptor or electrostatically
charged receiver
• Functions
• Charge the powder
• Transport powder into the “development zone”
• Fully develop the image, not the background
Material Deposition Presentation
55
Summary

The challenges of Electrostatic Deposition of Dry
Powder include:






Material formulation (Powder and Substrate)
Charge methodology
Transport means
Transfer mechanism
Many deposition technologies exist from the fields of
Electrophotography and Electrography
The advantages of electrostatic dry powder deposition
include:




Dry powder applications
Speed
Scalable to wide format
No solvents
Material Deposition Presentation
56
A Case Study – Powder Deposition
Dry powder coating of pharmaceutical tablets for
coating and/or drug loading
Project performed by Xactiv, Inc, www.xactiv.com
(formerly Torrey Pines Research)
 The development activity was carried out on behalf
of Phoqus Limited, www.phoqus.com

Material Deposition Presentation
57
Tablet Coating

Most tablets are coated
to:


Protect the tablet
Seal the tablet





From environment
Taste masking
Control drug release
Create brand
identification
Create desirable
appearance
Material Deposition Presentation
58
Tablet Coating Process Today



Batch
process
Solvent
based
Tumble dried
Material Deposition Presentation
59
Problems with the Current
Process



Liquids and solvents
 Compatibility problems with certain drug actives
 Environmental problems
 Drying costs
Quality
 Tablet damage due to aggressive tumbling
 Variation in coating thickness
Batch process
 Minimum lot size very large
 No individual tablet customization
 Expensive wastage if problems occur
Not suitable for certain tablets, such as fast dissolving dosage forms
Material Deposition Presentation
60
The Technical Challenges

The challenges over those normally encountered in
Reprographics Industry:

3-D Tablet Surface


Use of many different powders and tablets


Most printing done on flat surfaces
In printing, there is typically one set of materials for a given
machine
Precision


+/- 10% typical in printing
+/- 2% required for this application
Material Deposition Presentation
61
The Solution

Improve, Customize, and Optimize “Electrostatic DryPowder Development” (EDPD)

As practiced in the Reprographics Industry for over 50 years
Material Deposition Presentation
62
Deposition Applicator of Choice


Rotating magnet DCD system
Permanently magnetized carrier
Both provide vigorous mixing in
development zone
Material Deposition Presentation
63
Pharmaceutical EDPD Housing
Elements Licensed from Heidelberg
Material Deposition Presentation
64
Critical Coating Materials

DCD Carrier materials



Strontium and manganese ferrite powder, 40  – 80 
Silicone, Acrylic or Fluoro-Silicone coated
Coating powders




Many formulations
Various proprietary resins
Water soluble
Low glass transition temperatures
Material Deposition Presentation
65
Tablet Holding Requirements



Securely hold individual tablets
Make electrical contact to body of tablet
Create an electrical shield:


To prevent contamination of holder
Shut-down development of powder on tablet
Material Deposition Presentation
66
Tablet Holder
Ejector/Electrode
Conductive
Flexible Cup
Shield
(reverse biased)
Vacuum
Connection
Material Deposition Presentation
67
Coating Uniformity Issues
Weak field
Strong field
Weak field



Electric Field is a function of voltage difference and dielectric distance
In conventional coating practice, coating thickness varies with field
In copiers/printers, field is uniform because coated surface is flat. Tablet
is not flat, so field varies and coating thickness will vary
Material Deposition Presentation
68
Field Collapse Process
E = maximum
1
E
2
Time = 0
E
E=0
3
4
Time = Completion
Material Deposition Presentation
69
Coating Uniformity Results

Section through the corner of an EDPD coated tablet showing
uniformity of coating on top and around the edge
Material Deposition Presentation
70
Continuous Process

Section of coating drum with tablets
Material Deposition Presentation
71
The Finished Product
Material Deposition Presentation
72
A Case Study – Powder Deposition
Dry powder coating to make fuel cell electrodes
Activity performed by Xactiv, www.xactiv.com
(formerly Torrey Pines Research)
 Independent activity resulting in significant IP
 US Patent now issued
 Prepares Xactiv for position in renewable energy
markets

Material Deposition Presentation
73
Electrostatic Deposition
(Intermediate Dielectric Substrate)



60% PtC and 40% PTFE mixture is
conducting
Apply voltage between conducting
mixture and dielectric coated electrode
Monolayer of PtC/PTFE particles is
induction charged and electrostatically
attracted to dielectric
Material Deposition Presentation
VA
74
Electrostatic Deposition Problems
(Intermediate Dielectric Substrate)




Some non-uniformity of deposited layer
requires conditioning
Monolayer is only ~0.5 mg/cm2
Multiple transfix steps would be required to
achieve target Pt loadings
Need to repeatedly clean and neutralize
intermediate dielectric substrate
Material Deposition Presentation
75
Xactiv Conductive-Conductive Deposition
Particle Induction Charging & Detachment via Field Intensification
Weak Electric Field
for Deposition
VA
Electric Field
Intensification for
Induction Charging
& Detachment
Electrode
structures
Material Deposition Presentation
76
Xactiv Cond-Cond Implementation
Magnetic Brush Deposition
Carbon Paper
Air Gap
Paddle Wheel
Elevator & Metering
S
N
Magnetic Brush
Rotating Magnets
Stationary Sleeve
S
N
S
N
N
S
Cross Mixer
Material Deposition Presentation
77
Magnetic Brush Unit
Material Deposition Presentation
78
Magnetic Brush Structure
Material Deposition Presentation
79
Magnetic Brush Forces
Carbon Paper
VA
N
Material Deposition Presentation
80
Non Contact Magnetic Brush Deposition
Carbon Paper
Electric field intensified for
induction charging &
detachment of PtC/PTFE blend
VA
N
Material Deposition Presentation
81
Surrogate “Tribo” Fixture
Theory
Enables rapid evaluation of
materials, concentrations,
blend and mixing
conditions.
VA
S
N
S
N
S
Motor
Material Deposition Presentation
82
“Tribo” Fixture
Material Deposition Presentation
83
PtC/PTFE on Carbon Paper
Material Deposition Presentation
84
Deposited Powder Characteristics




PtC/PTFE powder layer has electrostatic
adhesion/cohesion but is low
The magnetic brush must be gapped from the carbon
paper to enable multilayer powder deposition
Q/M of powder blend depends on applied voltage but
magnitude independent of polarity
Since magnetic brush architectures prefer underside
deposition on a receiver, a minimum vacuum can be
provided for increasing the powder adhesion during the
electrostatic deposition process
Material Deposition Presentation
85
PtC/PTFE Density vs Depositions
with “Tribo” Fixture
2
Mass/unit area (mg/cm )
(Fixed field, Blend of 60% 15%PtC & 40% Teflon mixed with carrier)
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
5% Developer .25 gram loading
11% Developer .15 gram loading
Require ~5 & ~10 mg/cm2
for anode and cathode,
respectively
0
1
2
3
4
5
6
7
8
Number of Depositions
Material Deposition Presentation
86
Q/M & Percent Powder Detachment
Q/M ( C/g) &
Detachment (%)
Carbon/Teflon powder blend (60%/40%) at 5% with carrier
20
10
Q/M
Detachment
0
-3000
-2000
-1000
0
1000
2000
3000
-10
-20
Applied Voltage (volts)
Material Deposition Presentation
87
Vacuum Assisted
Magnetic Brush Deposition
Vacuum Plenum
Porous/Conducting
Support
Carbon Paper
S
N
S
N
S
N
VA
N
S
Material Deposition Presentation
88
What This Means





Ability to electrostatically deposit conductive &/or
insulative powder blends
Ability to deposit thin or thick layers of powder blend
onto conductive substrate
Control of layer thickness by electrostatic field
strength (voltage and distance) and dwell time
(process speed)
Enables low cost continuous manufacturing process
Dry deposition method can enable improved fuel cell
performance by circumventing possible platinum
catalyst contamination by current wet methods
Material Deposition Presentation
89
Electrode Fabrication Process
Transport Belt with
Electrostatic Grip
Powder
Radiant Heat Consolidation
Sintering
Developer unit
Carbon
Paper Feed
• Sheet fed architecture shown, may also be configured as a web
fed system
• Multiple Developer units can be used for multiple layers or
multiple depositions
3/22/2016
Torrey Pines Research, Inc.
90
Linear Plate Translator & Magnetic Brush
Material Deposition Presentation
91
Powder Blend Deposition on Carbon Paper
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10 cm square carbon paper attached to holder with porous plate
for vacuum assist
Developer with 60% PtC (10% Pt) and 40% Teflon blend mixed
with permanently magnetized ferrite carrier beads at
concentration of 4%
500 g of mixture loaded in developer unit sump of 12 cm width
Magnet assembly rotated at 50 rpm, and carbon paper translated
at speed of 2mm/s
Carbon paper biased at +2000 volts across 5mm gap
Deposit 4.2 mg/cm2 of powder blend after 2 passes
Production system would use 2 rolls in a single pass
Material Deposition Presentation
92
Powder Blend Consolidation
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Particle-to-particle contact of Teflon required prior to heating
Achieved by compacting the powder layer with pressure
10 cm square samples consolidated with pressure (200 psi) from
hydraulic press
Rubber sheet (3 mm thick) attached to one of the two pressure
plates
Release layer (paper) in contact with powder
Roll pressure likely feasible for production environment
Material Deposition Presentation
93
Powder Blend Sintering
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Nitrogen purged oven at 355oC used to sinter
consolidated powder on carbon paper for 4 min.
Alternative sintering methods are likely feasible for
production environment
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Resistive heating of carbon paper in inert atmosphere
Flash radiant heating
Material Deposition Presentation
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Sintering via Flash Radiant Heating
Transport Belt
Carbon Paper
PtC/PTFE
N2 ?
Flash Lamp Cavity
Material Deposition Presentation
95
Results – Surface Morphology
25x
500x
Material Deposition Presentation
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Results - Dispersion Uniformity
Platinum
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Carbon
SEM from Deposited
Layer
Fluorine
Material Deposition Presentation
97
Results - Functionality
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Deposited ~ 5 mg/cm2 on 4”x4” carbon paper
Consolidated and sintered layer
Measured 75% of ‘normal’ platinum
Assembled as electrode into fuel cell test module
Exceeded ‘normal’ cell output at 200mA/cm2
No degradation after 6 months of operation
Material Deposition Presentation
98
Any Questions???
Material Deposition Presentation
99