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Title: Nanostructured,%20multifunctional%20films%20prepared%20by%20thermionic%20vacuum%20arc%20technology


1
Nanostructured, multifunctional films prepared by
thermionic vacuum arc technology
Cristian P. LUNGU
Elementary Processes in Plasma and Applications
Group NATIONAL INSTITUTE FOR LASERS, PLASMA AND
RADIATION PHYSICS Magurele - Bucharest Romania
2
NATIONAL INSTITUTE FOR LASERS, PLASMA AND
RADIATION PHYSICS
Group Elementary Processes in Plasma and
Applications Contact person Dr. C. P.
Lungu E-maillungu_at_infim.ro Webwww.inflpr.ro Gro
up members 1 Professor, 5 PhD Researchers, 3
Researchers, 1 Assist. Res., 4 Students, 3
Technical staff.
Team 1. Prof. Dr. Musa Geavit, 2. Dr. Mustata
Ion, 3. Dr. Lungu P. Cristian, 4. Dr. Popa
Silviu Dan, 5. Dr. Ciobotaru Luminita, 6.Dipl.
Phys. Lungu Ana Mihaela, 7. Dipl. Eng. Phys.
Chiru Petrica, 8. Dr. Surdu Bob Cristina, 9.
Dipl. Phys. Brinza Ovidiu, 10. Techn. Dragusin
Vasile, 11. Techn. Balint Mihaela, 12. Techn.
Ilie Florian, 13. Techn. Zaroschi Valer, 14.
Student Barbu Ionut, 15. Student Badulescu
Marius, 16. Student Vizitiu Cristina, 17. Student
Budaca Radu.
  • Cooperation
  • National Institute of Micro and Nanotechnologies,
  • National Institute of Materials Physics,
  • Ovidius University Constanta,
  • Politehnica University, Bucharest,
  • Bochum University,
  • Commenius University, Bratislava
  • Japan Ultra-high Temperature Materials Research
    Institute

3
NATIONAL INSTITUTE FOR LASERS, PLASMA AND
RADIATION PHYSICS
The group developed an original technology
called Thermionic Vacuum Arc (TVA), suitable
for nanostructured, multifunctional film
preparation
Applications DLC coatings for MEMS
applications Tribological coatings Giant
magnetoresistive (GMR) films High temperature
resistant to oxidation coatings
4
  • The main advantages of the TVA method
  • - Deposition of pure metal film in high or ultra
    - high vacuum conditions (lt10-4torr)
  • - No gas consumption and gas incorporation in the
    growing film
  • - The growing thin film is bombarded just during
    deposition with the ions of the depositing
    material insuring the compactness of the film
  • - The energy of bombarding ions can be controlled
    and can be even changed during deposition
  • The film is nanostructured and the surface of the
    deposited film is smooth
  • The deposition rate can be easily controlled and
    can be greater than in the sputtering case (0.1
    10 nm/s).

TVA apparatus. Volume 1m3 Base pressure lt10-6
torr DC Power supplies 6kV, 5A 5kV,1A 3kV, 2A
0.6kV, 20 A
TVA plasma during deposition on turbine blade
5
THERMIONIC VACUUM ARC (TVA) PRINCIPLE
An intense thermoelectronic emission from an
heated cathode (a tungsten filament) is focused
by a Whenelt cylinder on the anode.
The anode consists of a crucible, filled with the
material to be deposited. This assembly is
mounted inside a vacuum vessel.
6
Working parameters used in the TVA technology for
DLC film deposition
cathode- anode (sizes) TVA Carbon depositions
Anode diameter 10 mm Current intensity 0.3 - 1.25 A Time300-600 s
Anode length 40 mm Potential 300 V- 2 kV Rate 0.5-10 nm/s
cathode-anode distance 4 mm Working pressure 10-6 torr Thickness gt100 nm
7
TEM equipment
Diamond like carbon films observed by High
Resolution Transmission Microscopy (HRTEM) and XPS
  • Philips CM 120 ST
  • Max. HT 120kV
  • Resolution 1.4 ?
  • Magnification 1.2M
  • Compustage 5 axis
  • Remote control
  • Analysis Software
  • HP CD-Writer

8
HRTEM and SAED
XPS analysis
XPS C1s peak deconvolution sp3 bonds 89.3,
sp2bonds 10.7
Image of carbon thin film and electron
diffraction.
9
Low friction coatings for plain bearings
Low friction coating materials are new classes of
advanced materials, which exhibit a reduced
coefficient of friction in dry sliding and raised
wear resistance.
Overlay
Bearing alloy
Back steel
The overlays that provide seizure, wear
resistance and conformability are usually made by
electroplating of 10 mm - 20 mm thick Pb alloy.
10
The engine bearing
Main Bearing
Connecting Rod Bearing
Connecting Rod Bearing
Main Bearing
11
Drastically decrease of the coefficient of
friction by increasing the graphite (DLC)
concentration in the overlay sample (a) 44.82
massC sample (b) 19.27massC Ag
concentration balance
Plain bearings for automotive applications coated
with antifriction Ag/DLC overlay
12
GRANULAR, MAGNETOREZISITIVE FILMS
Substrate
  • Two independents TVA guns
  • Every gun independent filament and dc supply
  • A metallic screen separates the two TVA
    discharges.

13
AFM images of the CoCu films
AFM Images of the FeCu films
14
Fe concentration of the Fe Cu films
Magnetorezisitive effect of the FeCu film
FeCu films non-treated and thermally treated
NiCu films non treated and thermally treated
15
High-temperature oxidation resistant coatings
Refractory metals such as W, Mo, Ta and Nb are
promising candidates for the development of new
kinds of heat resisting materials (One of their
most fatal shortcomings is low resistance against
oxidation at high temperatures)
This problem is expected to be solved by forming
multi-layered coatings
  • a barrier against coming and outgoing elements
    (Re),
  • a reservoir supplying lost elements (Re-Ni-Cr)
    and
  • a heat resistant layer (Ni-Al).

16
Re
Mo
Photograph of the Re ingot during deposition
17
Nb superalloy (Optical micrograph
Re
Nb superalloy
SAED
HRTEM
SEM
Selected area diffraction (SAED), high resolution
transmission microscopy (HRTEM) and scanning
electron microscopy (SEM) images of the
nanostructured Rhenium film deposited on Nb
superalloy by TVA
18
DTA and TGA analysis of Re-Cr film
SEM analysis of Re-Cr film
19
CONCLUSIONS
TVA technology can be used for preparation of
nanostructured multifunctional films
Applications DLC for MEMS and high Emissivity,
Tribological, GMR, and High Temperature
Resistant to Oxidation films. Ag-DLC films with
low coefficient of friction were prepared to be
applied at the plain bearing for automotive
applications. Were obtained granular films with
GMR effect (R(H)-R(0)/R(0)) in Co-Cu films in
the range of 5 and 10 without post-discharge
treatment and about 33 with thermal treatment
after deposition. In the case of de Fe-Cu films
the obtained maximum effect was of 38, leading
to the possibility to use the films at
magnetoresistive sensors preparation. The Re-Cr
antioxidation, high temperature resistant films
are used for thermal barrier coatings of the
turbine blades for more efficient energy
conversion.
20
REFERENCES
  1. C.P.Lungu, Nanostructure influence on DLC-Ag
    tribological coatings, Surf. and Coat. Techn, in
    print, (2005).
  2. C. P. Lungu, I. Mustata, G. Musa, A. M. Lungu, V.
    Zaroschi, K. Iwasaki, R. Tanaka, Y. Matsumura, I.
    Iwanaga, H. Tanaka, T. Oi, K. Fujita Formation
    of nanostructureed Re-Cr-Ni diffusion barrier
    coatings on Nb superalloys by TVA method, Surf
    and Coat. Techn, in print, (2005).
  3. V. Kuncser, I. Mustata, C. P. Lungu, A. M. Lungu,
    V. Zaroschi, W.Keune, B. Sahoo, F. Stromberg, M.
    Walterfang, L. Ion and G. Filoti Fe-Cu granular
    thin films with giant magnetoresistance by
    thermionic vacuum arc method Preparation and
    structural characterization, Surf and Coat.
    Techn, in print, (2005).
  4. C. P. Lungu, K. Iwasaki, K. Kishi, M. Yamamoto
    and R.Tanaka, Tribo-ecological coatings prepared
    by ECR-DC sputtering, Vacuum, 76, Issues 2-3,
    (2004) 119-126.
  5. C. P. Lungu, I. Mustata, G. Musa, V. Zaroschi,
    Ana Mihaela Lungu and K. Iwasaki Low friction
    silver-DLC coatings prepared by thermionic vacuum
    arc method, Vacuum, 76, Issues 2-3, 127-130,
    (2004).
  6. I. Mustata, C. P. Lungu, A. M. Lungu, V.
    Zaroski, M. Blideran and V. Ciupina Giant
    magnetoersisitve granular layers deposited by TVA
    method Vacuum, 76, Issues 2-3, 131-134 (2004).
  7. C. P. Lungu, K. Iwasaki Influence of surface
    morphology on the tribological properties of
    silver-graphite overlays, Vacuum, 66 (2002)
    385-391
  8. S.Q. Xiao, K. Tsuzuki, C. P. Lungu, O. Takai,
    Structure and properties of CeN thin films
    deposited in arc discharge, Vacuum, 51-4,
    pp.691-694, (1998).
  9. Shiqin Xiao, Cristian P. Lungu, Osamu Takai,
    Comparison of TiN deposition by rf magnetron
    sputtering and electron beam sustained arc ion
    plating, Thin Solid Films, 334, 1-2, pp. 173-177,
    (1998)
  10. O. Takai, M. Futsuhara, M. Shimizu, C. P. Lungu,
    J. Nozue, Nanostructure of ZnO Thin Films
    Prepared by Reactive rf Magnetron Sputtering,
    Thin Solid Films, 318, 1-2, pp. 117-119, (1998)

21
National Institute for Aerospace Researches Elie
Carafoli - INCAS SA, Bucharest 220, Iuliu
Maniu, Sect 6, Bucharest, Phone004.021.434.00.83,
Fax004.021.434.00.82 web www.incas.ro, e-mail
incas_at_aero.incas.ro
INCAS
3.4.2.2. TECHNOLOGIES ASSOCIATED WITH THE
PRODUCTION, TRANSFORMATION AND PROCESSING OF
KNOWLEDGE-BASED MULTIFUNCTIONAL MATERIALS
Dr.Ing V.Manoliu manoliu_at_incas.ro
22
PLASMA SPRAY PROCESSING
The fundamental characteristics of plasma process
are represented by the assured flame temperature,
about 15000 Celsius degrees, jet speed about 300
m/s, layer porosity about 2. The main parameters
of the plasma process are sketched as follows
  • Plasma parameters
  • Air dilution
  • Gas composition
  • Plasma jet temperature
  • Speed
  • Powder
  • Distribution,size, grain shape
  • Spray speed distribution
  • Staying time in plasma
  • Flame
  • Flame speed
  • Spraying distance
  • Under layer
  • Temperature
  • Residual tension control
  • Particle impact speed
  • Nozzle
  • Flow gas
  • Powder flow

23
Table no1 The potential
application of the plasma coatings
  • - high potential
  • - industrial application
  • or in progress of
  • introducing
  • - in progress of development
  • Without symbol unexplored potential

1 anticorrosive protections 2 anti wear
protections 3 electronic proprieties 4
radiation 5 chemical/biological proprieties
6 ended form 7 restore 8 powder
processing 9 sensitive composite 10
unstable materials 11 amorphous coatings
trough solidification
24
  • The process limits are specially determined by
    the reduced adherence between metal support and
  • bonding layers, high porosity and partial
    oxidation of the particles.
  • Fundamental problems to be solved in our opinion
    by the research in the field are represents by
    the
  • Plasma generator power increase
  • Powder flow speed increase
  • Comparable study of the condition by air pressure
    environment about layers porosity, structure
    modification , deposition part
  • Realisation for management of the technological
    process, especial for ceramic layers of a relax
    structure with deliberate accomplished porosity
    and micro cracks
  • Computerised metallography and electronic
    microscopy investigations regarding the interface
    aspects, support - adherence layer - external
    layers and dynamic of the modifications induced
    by different mechanic and thermal stresses.

Fig. 1 Plasma jet installation
25
3.4.2.2.3. MULTIFUNCTIONAL CERAMIC THIN FILMS
WITH RADICALLY NEW PROPRIETIES
INCAS have the experience to achieve some duplex,
triplex layers, FGM - functionally graded
materials, ceramics for industrial proposed
especial for hot parts of turbojet , for some
metallurgy parts, power industry, etc. The aimed
parts are stressed at erosive, corrosive wear,
thermal shock, sliding friction, which can work
simultaneously at high values. The ceramic
layers unanimous utilized, generally partial
stabilized zirconia base, have as main servitude,
the major difference between thermal expansion
coefficients values of ceramic layers and
metallic support during thermal shock and
associated induced internal stressed. To
decrease the thermal shock effect on the ceramic
layers, multilayered structures, FGM, etc. are
utilized. Each intermediate layer composition is
graded between external layers (internal and
external). A progress in this domain, is
represented by the recent experimental studies
performed by Lewis Research Center, Cleveland,
Ohio, for plasma sprayed coatings. An improved
bond coat, incorporating metallic or ceramic and
cermets layers has been demonstrated to increase
the thermal fatigue life of a plasma sprayed TBC
by a factor of two or more. Utilizing this
system, the second layer of the bond coat
incorporates a fine dispersion of a particulate
second phase in a MeCrAlY matrix. The second
phase is required to have a coefficient of
thermal expansion as low as possible or
preferable lower than yttrium zirconium layer and
it must be stable up to intended temperature,
chemically inert with respect to the MeCrAlY
matrix and must be chemically compatible with
the thermal grown alumina scale.
26
INCAS has in progress evaluation experiments of
the triplex layer type MeCrAlY/MeCrAlY 90
Al2O3 10/ZrO2. Y2O3 obtained by plasma spray
technology .
Fig. 2 Ceramic and bonding layers, SEM imagine
Fig. 3 Zr associate distribution
Within the consortium, in this direction, INCAS
is able to participate especially in the
achievement of some multifunctional layers ,
thermal shock stressed .
27
Quick thermal shock test installation for
multifunctional ceramic coatings
  • Protection layers and especial ceramics have
    main servitude lower resistance at thermal
    shock.
  • For aeronautical application, rockets,
    metallurgical, power industries, is important the
    behavior of
  • this coatings in limited functional conditions -
    with additionally requests.
  • Thermal shock classical installation mentioned
    in literature have heating
  • cooling cycle with substantial low speed than
    extreme functional conditions. In the same
  • context are not testing methods in extreme
    condition, unanimous accepted.
  • The main characteristics of the proposed thermal
    shock installation
  • testing sample dimensions-rectangle LxWxH mm -
    25x25x2or circular ?25x12 mm
  • the test specimen materials metals, alloys,
    composite materials, ceramic materials, coatings
  • (enamel, multilayered, TBC, FGM, etc.)
  • maximum testing temperature 1400 degrees
    Celsius
  • heating time from the environment temperature
    till the testing temperature15150 sec
  • cooling time from the testing temperature till
    the environment temperature15 250 sec
  • temperature speed measurement 150 ms
  • sample view during the test
  • temperatures measurement during all the time test
  • samples photo in the heating and cooling areas
  • samples lighting in the heating and cooling
    areas
  • manual cycle

28
3.4.2.3. ENGINEERING SUPPORT FOR MATERIALS
DEVELOPMENT
3.4.2.3.1. MATERIALS BY DESIGN MULTIFUNCTIONAL
ORGANIC MATERIALS
Nanocomposites epoxy-Montmorillonite
Nanocomposites are a new class of advanced,
nanometer-scale multiphase polymer composites
that often display many enhanced physical
properties strength, hardness, thermal and
viscoelastic properties. Nanocomposites are
synthesized by dispersing expholiated clays,
nanometer particle and aggregates into a polymer
matrix (epoxy) or by infiltrating epoxy into the
interlayer structure of layered silicates. INCAS
in cooperation with ICECHIM Bucharest develop
researches regarding nanocomposites epoxy-
Montmorillonite (aluminum hydrate silicate), via
second way. In the first stage some samples of
epoxy resin as such and epoxy-10 Montmorillonite
(weight) are performed. The mechanical testing
results up to date are synthesized in table 2.
Table no. 2 Epoxy resin characteristics
with and without Montmorillonite
It is to notice the significant effect of the
Montmorillonite addition upon the elasticity
modulus. The researches will be continued with
complementary studies regard nanocomposites-epoxy-
glass fiber, nano epoxy-fibers composites and
maybe nano epoxy-carbonnanotube, incorporated..
29
3.4.3.1. DEVELOPMENT OF NEW PROCESSES AND
FLEXIBLE, INTELLIGENT MANUFACTURING SYSTEMS
3.4.3.1.1. NEW PRODUCTION TECHNOLOGIES FOR NEW
MICRO-DEVICES USING ULTRA PRECISION ENGINEERING
TECHNIQUES
Carbon carbon composites nano-ceramic matrix
Carbon fiber and carbon-carbon was first
developed for aerospace technology (component in
missiles, reentry vehicles, in space shuttles as
structural parts and as brake lining and brake
disc material for civil and military
aircraft). Materials and Tribology Department of
INCAS realized performing carbon fiber (PAN
precursor) and carbon-carbon composites, phenolic
matrix. In fig. 4 and Fig. 5 the Debyegram of PAN
precursor and thermooxidate PAN are presented.
Intensity diminution of peak diffraction points
out adequate PAN stabilization.
Fig. 4 PAN Debyegram
Fig. 5 Debyegram of the thermooxidate PAN
30
Some characteristics of FC obtained are
synthesized in table 3.
Table 3
Characteristics of FC
31
In fig. 8 and fig. 9 are point out the effects
of thermal treatment upon density and mechanical
characteristics of the C-C composites.
  • Recently researches report on C-C composites and
    nano C-C composites as brake materials.
  • The main features of C-C as friction materials
    for aircraft brakes are
  • a great ablation heat (20.000 Kcal/Kg)
  • specific weight 1,7 1,9 Kg/dm3
  • friction coefficient 0,3
  • dimensional stability at high temperatures (small
    dilatation coefficient, max 2x10-6 v.s.10-5 for
    steel)

32
  • For concordance in tribological and antioxidant
    properties of C-C composites distinct solutions
    was
  • developed
  • FC - fiber (unidirectional 2D tissue, chopped,
    felt preform) and phenolic matrix with 25 CSi
    (reported
  • to phenolic resin)
  • Nanocomposites C-C ceramic matrix via so called
    LSI (Liquid Silicon Infiltration).
  • The sol gel SiO2 (50 weight reported to phenolic
    resin) infiltrated in a C-C by thermal
    treatment
  • at 1600C generate ceramic matrix (CSi). The
    results of tribological testing are presented in
    table no 5

Friction coefficients for C-C composites
Table no 5
In the future INCAS- Material and Tribology
Laboratory aims to achieve carbon fiber
composites ceramic matrix, via nanosilicium
carbide-mesophase, or to use polymeric precursor
(policarbosilane) for CSi matrix.
33
NATIONAL INSTITUTE FOR LASER, PLASMA AND
RADIATION PHYSICS, BUCHAREST,
ROMANIA
  • COMBINED MAGNETRON SPUTTERING AND ION
    IMPLANTATION A NEW HIGH ENERGY ION ASSISTED
    DEPOSITION METHOD TO PRODUCE HARD NANOCOMPOSITE
    COATINGS

Dr. Cristian Ruset, Head of Plasma Physics and
Nuclear Fusion Department ruset_at_infim.ro
34
THE CONCEPT AND SPECIFIC ASPECTS OF THE METHOD
  • A high voltage pulse discharge is superposed over
    the magnetron sputtering deposition and this is
    CMSII process.
  • The components to be coated are positioned into
    the deposition chamber on a special jigging
    system, insulated to 100 kV, and they are
    connected to a high voltage pulse generator. The
    plasma ions from the magnetron discharge are
    accelerated during the high voltage pulses and
    strike initially the substrate and then the layer
    itself during its growing with energies of tens
    of keV. Typical parameters of the high voltage
    pulse discharge are U 50kV, ? 20 ?s, f 25
    Hz.
  • As a result of this periodical ion bombardment
    the following effects occur
  • - A significant enlargement (up to 5 7 ?m) of
    the layer-substrate interface resulting into a
    strong adhesion between the layer and the
    substrate. For conventional magnetron sputtering
    this interface is of 1?m.
  • - A featureless, extremely dense, pore free
    nano-structure is produced. The typical columnar
    structure of TiN does not exist any more. TEM
    analyses have shown crystallites with a size of
    less than 10 nm.
  • - A high densification of the layer. Using a
    titanium magnetron target, nc-Ti2N/nc-TiN
    nanocomposite layers with a hardness of 25 ? 40
    GPa have been obtained.
  • - A stress relief at the interface and within the
    layer. Due to this effect, layers with a
    thickness of 10 50 ?m have been produced.
  • - Increase by a factor of 4 of the deposition
    rate comparing with standard magnetron
    sputtering. The actual deposition rate for
    nc-Ti2N/nc-TiN coating is 4 5 ?m/h.

35
SEM micrograph of the nc-Ti2N/nc-TiN coating
deposited by CMSII demonstrating its featureless
and extremely dense structure
36
Cross-sectional TEM microstructure (a) and plane
view TEM microstructure with corresponding SAED
pattern (b) of the nc-Ti2N/nc-TiN coating
deposited by CMSII
(a)
(b)
37
DEPTH PROFILES OF THE CONSTITUENTS FOR THE
COATINGS DEPOSITED BY SMS AND CMSII
(a)
(b)
38
OPTICAL MICROGRAPH OF A nc-Ti2N/nc-TiN COATING
25 ?m
39
POTENTIAL APPLICATION AREA FOR nc-Ti2N/nc-TiN
NANOCOMPOSITE COATINGS
  • Cutting tools
  • Forming tools (plastic injection dies)
  • Calibration tools
  • Drawing shafts and extrusion dies in pipe
    industry
  • Automotive industry (piston rings, fuel injection
    pumps, various shafts, etc.)
  • Hydraulics
  • Medical instrumentation
  • Orthopedic prostheses, etc.

40
END MILLS COATED WITH nc-Ti2N/nc-TiN
NANOCOMPOSITE LAYER
41
WEAR TEST RESULTS FOR END MILLS
42
WEAR TEST RESULTS OF THE TURNING CUTTERS ON
BRONZE B11G21
No. Surface treatment Number of grooves
made with one cutter before
re-sharpening 1 No treatment just standard
cutter 1 2 Plasma nitriding
3 3 Plasma nitriding
nc-Ti2N/nc-TiN coating 12
43
CEMENTED CARBIDE INSERTS COATED WITH
nc-Ti2N/nc-TiN
44
WEAR TEST RESULTS FOR CEMENTED CARBIDE INSERTS
COATED WITH nc-Ti2N/nc-TiN
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