Coatings Technology Handbook Episode 1 Part 10 pptx

31-30 Coatings Technology Handbook, Third Edition
42. A. Etspuler and H. Suhr, J. Appl. Phys., A48, 373 (1989).
43. E. Feurer, S. Kraus, and H. Suhr, J. Vac. Sci. Technol., A7, 2799 (1989).
44. H. Holzschuh and H. Suhr, J. Appl. Phys., A51, 486 (1990).
45. H. Holzschuh and H. Suhr, Appl. Phys. Lett., 59, 470 (1991).
46. M. D. Hudson, C. Trundle, and C. J. Brierly, J. Mater. Res., 3, 1151 (1988).
47. R. A. Kant and G. K. Huber, Surf. and Coat. Technol., 51, 247 (1992).
48. R. Prange, R. Cremer, D. Neuschutz, Surf. and Coat. Technol, 133–134, 208–214 (2000).
49. E. Kubel, Metall. Powder Rep., 43, 832 (1988).
50. B. Leon, A. Klumpp, M. Perez-Amor, and H, Sigmund, Appl. Surf. Sci., 46, 210 (1990).
51. Y. S. Liu, in Tungsten and Other Refractory Metals for VLSI Applications. R. L. Blewer, Ed., Mater.
Res. Soc. Proc., 43 (1985).
52. C. Mitterez, M. Rauter, and P. Rodhammer, Surf. and Coat. Technol., 41, 351 (1990).
53. S. Motojima and H. Mizutani, Appl. Phys. Lett., 54, 1104 (1989).
54. A. Chayahara, H. Yokoyama, T. Imura, and Y. Osaka, Appl. Surf. Sci., 33/34, 561 (1988).
55. C. Oehr and H. Suhr, J. Appl. Phys., A49, 691 (1989).
56. D. Hofmann, S. Kunkel, H. Schussler, G. Teschner, R. Gruen, Surf. and Coat. Technol, 81, 146–150
(1996).
57. R. D. Arnell, Surf. and Coat. Technol., 43/44, 674 (1990).
58. E. Bergmann, E. Moll, in Plasma Surface Engineering, Vol. 1. E. Broszeit, W. Muenz, H. Oechsner,
G. Wolf, Eds, Heidelberg: DGM-Verlag, Oberursel, 1989, p. 547.
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32

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32

Cathodic Arc Plasma

Deposition

32.1 Introduction

32-

1
32.2 Cathodic Arc Plasma Deposition Process

32-

1
32.3 Cathodic Arc Sources

32-

3
32.4 Cathodic Arc Emission Characteristics

32-

3
32.5 Microdroplets

32-

4
32.6 Recent Developments

32-

5
References

32-

7

32.1 Introduction

The cathodic arc plasma deposition (CAPD) method

1,2

of thin film deposition belongs to a family of ion
plating processes that includes evaporative ion plating

3,4

and sputter ion plating.

5,6

However, the CAPD
process involves deposition species that are highly ionized and posses higher ion energies than other ion
plating processes. All the ion plating processes have been developed to take advantage of the special
process development features and to meet particular requirements for coatings, such as good adhesion,
wear resistance, corrosion resistance, and decorative properties.

The cathodic arc technique, having proved to be extremely successful in cutting tool applications, is
now finding much wider ranging applications in the deposition of erosion resistance, corrosion resistance,
decorative coatings, and architectural and solar coatings.

32.2 Cathodic Arc Plasma Deposition Process

In the CAPD process, material is evaporated by the action of one or more vacuum arcs, the source
chamber, a cathode and an arc power supply, an arc ignitor, an anode, and substrate bias power supply.
Arcs are sustained by voltages in the range of 15 to 50 V, depending on the source material; typical arc
currents in the range of 30 to 400 A are employed. When high currents are used, an arc spot splits into
multiple spots on the cathode surface, the number depending on the cathode material. This is illustrated
spots move randomly on the surface of the cathode, typically at speeds of the order of tens of meters per
second. The arc spot motion and speed can be further influenced by external means such as magnetic
fields, gas pressures during coatings, and electrostatic fields.
Materials removal from the source occurs as a series of rapid flash evaporation events as the arc spot
migrates over the cathode surface. Arc spots, which are sustained as a result of the material plasma
generated by the arc itself, can be controlled with appropriate boundary shields and/or magnetic fields.

H. Randhawa

Vac-Tec Systems, Inc.

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© 2006 by Taylor & Francis Group, LLC
material being the cathode in the arc circuit (Figure 32.1). The basic coating system consists of a vacuum
in Figure 32.2 for a titanium source. In this case, an average arc current/arc spot is about 75 A. The arc

32

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Coatings Technology Handbook, Third Edition

FIGURE 32.5

Microdroplet emission from metals having different melting points.

FIGURE 32.6

Scanning electron micrographs showing surface topography of various films using modified arc
technology.
Cu
Ta
Cr
1.50 kv 30 kv 002
30 kv 0141.00 kv
TiN ZrN
TiO
2
1.50 kv 30 kv 003

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33

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33

Industrial Diamond and

Diamondlike Films

33.1 Introduction

33-

1
33.2 Diamond and Diamondlike Films

33-

1
33.3 Film Deposition Techniques

33-

2

33.4 Diamond and Diamondlike Film Properties

33-

3
33.5 Potential Applications

33-

4

33.1 Introduction

The mechanical, electrical, thermal, and optical properties of diamond make it attractive for use in a
variety of different applications ranging from wear-resistant coatings for tools and engineered compo-
nents to advanced semiconductor structures for integrated circuit devices.

1

Until recently, diamond
“coating” was done by bonding single-crystal diamond grits to the surfaces of the components to be
coated. Applications for diamond coatings were limited, therefore, to tooling used for cutting and
grinding operations.
Recent advancements in plasma-assisted chemical vapor deposition (PACVD) and ion beam enhanced
deposition technologies make it possible to form continuous diamond and diamondlike carbon films on
component surfaces. There new films have many of the mechanical, thermal, optical, and electrical
properties of single-crystal diamond, and they make possible the diamond facing of precision tools and
wear parts, optical lenses and components, and computer disks, as well as the production of advanced
semiconductor devices. The most flexibility, in terms of properties of the deposited diamond films and
types of material coatable, is found when the films are formed using ion beam deposition techniques.

33.2 Diamond and Diamondlike Films

The ability to diamond-coat tools and engineered components required that diamond precursor material
be condensed from a vapor phase as a continuous film onto the surface of the component to be coated.
Furthermore, the deposition must proceed so that the vapor-deposited material condenses with the
structure and morphology of diamond. Diamond is a metastable form of carbon; as such, when con-
densed from a vapor or from a flux of energetic particles, it will tend to assume its most thermodynam-
ically stable state or form — graphite. With advanced processes like chemical vapor deposition (CVD)
and ion beam enhanced deposition, it is possible to influence, to a certain degree, the energy and charge

states of the particles in the vapor phase, thus allowing some control over the energy state (stable or
metastable) and crystallographic and stoichiometric form of the deposited films. Thus, it is feasible to

Arnold H. Deutchman

BeamAlloy Corporation

Robert J. Partyka

BeamAlloy Corporation

DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM
© 2006 by Taylor & Francis Group, LLC
Plasma-Assisted Chemical Vapor Deposition (PACVD)
References
33-5
Te c hniques • Ion Beam Enhanced Deposition (DIOND)

33

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Coatings Technology Handbook, Third Edition

17. O. Matsumoto et al.,

Thin Solid Films,

146

, 283 (1986).
18. N. Fujimori et al.,

Vacuum,



36

, 99 (1986).
19. S. Aisenberg et al.,

J. Appl. Phys.,



42

, 2953 (1976).
20. E. G. Spenser et al.,

Appl. Phys. Lett.,



29

, 228 (1976).

21. J. H. Freeman et al.,

Nuclear Instrum. Methods, 135

, 1 (1976).
22. T. Miyazawa et al.,

J. Appl. Phys.,



55

, 188 (1984).
23. J. W. Rabalais et al.,

Science,



239

, 623 (1988).
24. C. Weissmantel,

Thin Solid Films,



92

, 55 (1982).
25. M. J. Mirtich et al.,

Thin Solid Films,



131

, 245 (1985).
26. C. Weissmantel et al.,

J. Vac. Sci. Technol. A4,



6

, 2892 (1985).
27. A. H. Deutchman et al.,

Ind. Heating, LV(7),



12

(1988).

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34

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34

Tribological Synergistic

Coatings

34.1

34.2 What Are Synergistic Coatings?

34-

2
34.3 Wear Testing

34-

3
34.4 Coating Families

34-

3

34.1 Introduction

The solution of wear and many related problems for any application is very much experience dependent.
A scientific basis for resolving these problems unfortunately has not yet been found. Using experience
and history, it is possible to recommend a number of potential solutions; however, the ultimate proof is
in the actual trial of the application. This is because there are so many variables within each application
that the slightest change could make a difference in the selection of the appropriate coating. Even though
applications appear to be identical, there are always slight differences such that the same coating selection
will not always perform in the same manner.
The production of synergistic coatings on steel (Nedox) or aluminum (Tufram) is based on the
principle of infusion of a dry lubricant or polymer into the coatings. General Magnaplate has developed
a family of such coatings (Nedox), each one representing specific properties, such as hardness, lubricity,
corrosion protection, and dielectric strength. The standard hardfacing for steel is an electroless nickel
coating. There are a number of electroless nickels that vary the phosphorus content and consequently
have differences in hardness and corrosion resistance. Choice of such a coating varies and is based on
the application requirements.
Synergistic coatings for aluminum (Tufram) have been used successfully for many years. The system
can accommodate almost all aluminum alloys, provided a copper content of 5% and a silicon content
of 7% are not exceeded. Higher percentages of these constituents (set up too great a change in substrate
resistivity, hence) prevent the buildup of required film thickness.
The prime purpose of the Tufram system is to produce films having properties such as improved wear
resistance, better surface release (lower coefficient of friction), good corrosion resistance, and high
dielectric strength.
The principle of these coatings is based on a hardcoat after which a polymer or dry lubricant is infused
into the coating substrate.
All coatings are used in a wide variety of industries. Some are in compliance with the regulations of
the U.S. Food and Drug Administration and can be used in food and medical applications.

Walter Alina

General Magnaplate Corporation

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© 2006 by Taylor & Francis Group, LLC
Polymer Coatings (Lectrofluor) • Magnesium (Magnadize) and
Introduction 34-1
Titanium (Canadize) • Titanium Nitride (Magnagold)

Tribological Synergistic Coatings

34

-5

TA BLE 34.1

Friction Data by Materials

Upper Plate

a

Lower Plate

a

Coefficients of Friction
Static Kinetic

IceIce 0.000 0.000
Hi-T-Lube Hi-T-Lube 0.251 0.217
Hi-T-Lube Steel 0.056 0.049
Hi-T-Lube

b

Hi-T-Lube

b

0.034 0.034
Lectrofluor 604 Glass 0.190 0.172
Lectrofluor 604P Teflon 0.106 0.089
Magnagold Magnagold 0.245 0.211
Magnagold Magnagold

+

Ni 0.484 0.357
Magnagold Teflon 0.150 0.123
Magnagold Steel 0.300 0.246
Magnagold Nickel 0.326 0.259
Magnagold Glass 0.177 0.155
Magnagold Aluminum 0.248 0.220
Magnagold Chromium

a

0.193 0.174

Magnagold Steel 0.313 0.285
Magnagold Nickel 0.367 0.329
Magnagold Titanium P 0.559 0.494
Magnagold Copier paper 0.518 0.497
Magnagold MOS/2 0.304 0.270
Magnagold Hi-T-Lube 0.264 0.244
Magnagold Graphite over paper 0.260 0.234
Magnaplate TFE Magnagold

+

TFE 0.225 0.174
Magnaplate HCR Magnaplate HCR 0.198 0.174
Magnaplate HCR Glass 0.138 0.125
Magnaplate HCR Aluminum 0.346 0.289
Magnaplate HCR Teflon 0.142 0.120
Magnaplate HMF Hi-T-Lube

b

0.032 0.031
Magnaplate HMF Magnaplate HMF 0.160 0.147
Magnaplate HMF Teflon 0.059 0.053
Magnaplate HMF Glass 0.251 0.192
Magnaplate HMF Steel 0.212 0.181
Nedox S/F 2 Steel 0.301 0.260
Nedox S/F 2 Teflon 0.103 0.090
Nedox S/F 2 Nedox S/F 2 0.179 0.123
Nedox S/F 2 Glass 0.137 0.130
Tufram 604 Aluminum 0.429 0.371

Tufram H–2 Tufram H–2 0.171 0.139
Tufram H–2 Glass 0.203 0.169
Tufram H–2 Aluminum 0.377 0.264
Tufram H–2 Teflon 0.134 0.120
Tufram H–0 Tufram H–0 0.249 0.223
Tufram H–0 Glass 0.180 0.150
Tufram H–0 Aluminum 0.251 0.219
Tufram H–0 Teflon 0.121 0.103
Tufram L–4 Tufram L–4 0.184 0.173
Tufram L–4 Aluminum 0.353 0.294
Tufram L–4 Glass 0.256 0.189
Tufram L–4 Teflon 0.142 0.130
Tufram R66 Glass 0.162 0.149
Tufram R66 Tufram R66 0.148 0.115
Tufram R66 Aluminum 0.329 0.272
Tufram R66 Teflon 0.133 0.100
Aluminum Titanium A 0.413 0.376
Aluminum Titanium P 0.614 0.531
Aluminum Teflon 0.237 0.186
Aluminum Glass 0.175 0.137

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34

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Coatings Technology Handbook, Third Edition

Aluminum Aluminum 0.646 0.563
Aluminum Magnagold 0.304 0.263
Aluminum Chromium 0.199 0.185
Aluminum Nickel 0.258 0.233
Aluminum Steel 0.466 0.375
Chromium Chromium A 0.176 0.159
Chromium Aluminum 0.266 0.216
Chromium Magnagold 0.176 0.149
Chromium Nickel 0.405 0.356
Chromium Steel 0.254 0.210
Copier paper Copier paper 0.275 0.259
Graphite over paper Graphite over paper 0.322 0.302
Hard chromium Titanium P 0.344 0.304
Hard chromium Teflon 0.095 0.078
Hardcoated aluminum Glass 0.151 0.127
Hardcoated aluminum Teflon 0.178 0.157
Hardcoated aluminum Hardcoated aluminum 0.264 0.220
MOS/2 MOS/2 0.433 0.418
Nickel Teflon 0.148 0.120
Nickel Chromium 0.192 0.174
Nickel Aluminum 0.330 0.253
Nickel Magnagold 0.308 0.267
Nickel Nickel 0.317 0.279
Steel Titanium P 0.493 0.410
Steel Hi-T-Lube 0.254 0.218
Steel Graphite over paper 0.245 0.225
Steel Aluminum 0.349 0.247
Steel Magnagold 0.377 0.308
Steel Magnagold

+

Ni 0.675 0.607
Steel Teflon 0.269 0.269
Steel Nickel 0.723 0.553
Steel Glass 0.127 0.116
Steel Chromium 0.202 0.174
Steel Nickel 0.431 0.333
Steel Magnagold 0.218 0.194
Steel Nickel 0.353 0.315
Steel Steel 0.423 0.351
Te flon Titanium A 0.232 0.205
Te flon Titanium P 0.291 0.240
Te flon Hard chromium 0.210 0.191
Te flon Magnagold

+

Ni 0.209 0.160
Te flon Magnagold 0.161 0.114
Te flon Magnaplate HCR 0.178 0.167
Te flon Magnaplate HMF 0.172 0.154
Te flon Nedox SF2 0.149 0.120
Te flon Tufram H–2 0.137 0.127
Te flon Tufram H0 0.167 0.138
Te flon Tufram L4 0.149 0.131
Te flon Tufram R66 0.180 0.149
Te flon Teflon 0.083 0.070
Te flon Steel 0.184 0.157
Te flon Nickel 0.223 0.190

Te flon Hardcoated aluminum 0.207 0.183
Te flon Glass 0.097 0.097
Te flon Aluminum 0.194 0.177
Titanium A Steel 0.358 0.317

TA BLE 34.1

Friction Data by Materials

(Continued)

Upper Plate

a

Lower Plate

a

Coefficients of Friction
Static Kinetic

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Tribological Synergistic Coatings

34

-7

Titanium A Magnagold 0.264 0.226
Titanium A Hard chromium 0.375 0.332
Titanium A Aluminum 0.345 0.288
Titanium P Steel 0.369 0.283
Titanium P Magnagold 0.290 0.258
Titanium P Hard chromium 0.328 0.288
Titanium P Alumium 0.430 0.321
Titanium A Titanium A 0.359 0.303
Titanium A Teflon 0.174 0.142
Titanium P Titanium A 0.415 0.370
Titanium P Teflon 0.223 0.193

a

A superscript “a” indicates additional polish after coating; a “b” indicates
postburnishing — comparable to breaking in the surface.

TA BLE 34.2

Designation in
Ta ble 34.1 Description

Aluminum 6061 T6 grade (0.250) thickness
Steel 1032 grade H32 (0.250) thickness
Titanium A 6A1/4V (0.250) thickness
Titanium P Vacuum deposited at 10 to 5 torr, 2

µ

m thickness, purity 99.99%
Glass Tempered (0.250) thickness
Te flon White, virgin grade (0.250) thickness
Nickel Autocatalytic 6/8% phosphorus (0.001)
Hard chromium Industrial grade (0.0003)
Hard anodize 6061 T6 (0.002)
Tufram Proprietary aluminum coating
Nedox Proprietary treatment for steel and stainless steels and nonferrous metals
Hi-T-Lube Proprietary solid film metal alloy lubricant
Magnagold Proprietary method for vacuum coating of titanium nitride
Magnaplate HMF Proprietary ultrahard, high microfinish for most base metals
Magnaplate HCR Proprietary ultrahard and exceptionally corrosion-resistant coating for aluminum

FIGURE 34.2

T.M.I. slip and friction tester.

TA BLE 34.1

Friction Data by Materials

(Continued)

Upper Plate

a

Lower Plate

a

Coefficients of Friction
Static Kinetic

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Key to Materials and Coatings Listed in Table 34.1

34

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Coatings Technology Handbook, Third Edition

surface preparation. A combination of specialty designed equipment and chemical cleaning techniques
prepares the component surface to assure permanently interlocked anchoring of the “coating.” Conven-
tional vapor deposition applicators are not equipped with the extensive facilities that permit the meticulous
care and attention required in the precleaning phase of the process. The parts are mounted on a specially
designed cylindrical fixture, and then the entire work cylinder enters the vacuum chamber. A vacuum (1

×

10

–6

torr) is achieved, after which the system is purged with argon gas as an additional cleaning step.
Titanium metal (99.9%) is then vaporized by a plasma energy source. This is followed by the precise
introduction of nitrogen, the reactive gas, into the chamber. The parts to be coated are cathodically charged
by high voltage (dc), thereby attracting accelerated ions of titanium. Simultaneously, they combine with

nitrogen to produce the tightly adhering, highly wear-resistant titanium nitride PVD coating.

FIGURE 34.3

The Taber Abraser.

FIGURE 34.4

Weight loss following Taber abrasion for aluminum samples with various coatings.
10mg. 20 30 40 50 60
Hardcoat Anodized (Sealed)
Per MIL-A-8625 Type III, Class 1
Hardcoat Anodized (Unsealed)
Per MIL-A-8625 Type III, Class 1
19
mg.
42
mg.
4
mg.
Magnaplate HCR Coating
Weight Loss = mg. Per 10,000 Cycles,
CS-17 Wheel, 1000 gm. Load
Taber Abrasion (Aluminum)

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Tribological Synergistic Coatings

34

-9

Note

: Some alloys are sensitive to temperatures up to 900

°

F and can be reduced in hardness if the
substrate material selected is not heat compatible with this process. It is possible to lower processing
temperature to prevent certain steels from annealing; however, there may be a slight reduction in the
hardness of the titanium nitride coating.

FIGURE 34.5

Weight loss following Taber abrasion for steel samples with various coatings.

TA BLE 34.3

Some Physical Properties of Magnagold Coatings

Hardness

R

c

80 to 85

Chemical resistance to 30% concentrations of
nitric and sulfuric acids on copper and steel
substrates at ambient temperature
Virtually no attack
Alkali resistance Virtually no attack
Ta ber abrasion test, CS 10 wheel, 1000 g load,
10,000 cycles
Average weight loss >0.5 mg
Coating thickness 1 to 3

µ

m
Uniformity of thickness 15

×

10

–5

0.000015 in. (max.)
Crystal lattice Body-centered cubic,

a



=

4.249 ô
Density 5.44 g/cm

4

Thermal conductivity, cal/cm/sec/

°

C ~0.162 (at 1500

°

C)
~0.167 (at 1600

°

C)
~0.165 (at 1700

°

C)
~0.136 (at 2300

°

C)
Coefficient of thermal expansion

×

10

–6

cm/

°

C 9.35

±

0.04 (at 25 ~1100

°

C)
Electrical resistivity 40

µΩ

(at 27

°

C)
Thermonic emission work function 3.75 eV

Microhardness (Hu) 2050 kg/mm

2

(load 100 g)
10
mg.
20 30 40 50 60 70 80 90 100 110 120 130 140
73.5
mg.
134.4
mg.
27.7
mg.
31
mg.
Taber Abrasion (Steel)
Electroless Nickel Per Mil-C-26074 Class 1
(0.001 — No Heat Treatment)
Electroless Nickel Per Mil-C-26074 Class 2
(0.001 — With Heat Treatment)
Nedox SF-2 − 0.001 (Gen. Magnaplate Corp.)
Nedox CR + 0.001 (Gen. Magnaplate Corp.)

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34

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Coatings Technology Handbook, Third Edition

TA BLE 34.4

Wettability of Various Metal Surfaces

We ttability Metal Contact (Temperature/Condition)

Cu 180

°

(1100

°

C vac)
126

°

(1180

°

C vac)
148

°

(1560

°

C NH

3

)
136

°

(1130

°

C Ar)
Al 147

°

(850 to 1000

°

C vac)
135

°

(900

°

C Ar)
Cd 139

°

(450

°

C vac)
Pb 102

°

(450

°

C vac)
Sn 140

°

(350

°

C vac)
Bi 147

°

(370

°

C Ar)
Fe 100

°

(1500

°

C vac)
132

°

(1550

°

C Ar)
Co 104

°

(1550

°

C vac)
Ni ~70

°

(1550

°

C vac)
110

°

(1450 to 1500

°

C N

2

)

TA BLE 34.5

Static (S) and Kinetic (K) Coefficients of Friction for

Var iously Coated Components of a Panel Assembly

Upper Panel
Lower Panel Steel (4 to 8

µ

m in. RMS) Teflon

Steel (4–8 RMS) S: 0.534

±

0.079 0.184

±

0.029
K: 0.400

±

0.093 0.157

±

0.029
Magnagold (4–8 RMS) S: 0.218

±

0.028 0.161

±

0.014
K: 0.194

±

0.030 0.114

±

0.017

FIGURE 34.6

The Magnagold process sequence.
DC
Power
Source
Hearth

Travel
Rotate
Nitrogen
Vacuum
Parts Are
Rx Tured
To Carrier
Titanium

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Tribological Synergistic Coatings

34

-11

FIGURE 34.7

The Magnagold production setup.

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35

-1

35

Chemical Vapor

Deposition

35.1 Introduction

35-

1
35.2 Process

35-

1
35.3 Applications

35-

3
35.4 Summary

35-

9
Bibliography

35-

10

35.1 Introduction

Chemical vapor deposition (CVD) is a technique of modifying properties of surfaces of engineering
components by depositing a layer or layers of another metal or compound through chemical reactions
in a gaseous medium surrounding the component at an elevated temperature. In formal terms, CVD
may be defined as a technique in which a mixture of gases interacts with the surface of a substrate at a
relatively high temperature, resulting in the decomposition of some of the constituents of the gas mixture
and the formation of a solid film of coating of a metal or a compound on the substrate.

35.2 Process

A modern CVD system includes a system of metering a mixture of reactive and carrier gases, a heated
basic arrangement of various components of industrial CVD systems.
The gas mixture (which typically consists of hydrogen, nitrogen, or argon, and reactive gases such as
metal halides and hydrocarbons) is carried into a reaction chamber that is heated to the desired temper-
ature by suitable means. The various techniques include resistance heating with Kanthal, Globar (SiC)
or graphite heating elements, or induction. In some cases, the substrate is heated directly by passing an
electric current through it.
variations of the conventional method have been developed over the last few decades. These include
moderate-temperature CVD (MTCVD), plasma-assisted CVD (PACVD), and laser CVD (LCVD). In the
MTCVD process, the reaction temperature is reduced to below about 850

°

C by the use of metalorganic
compounds as precursors. Therefore, this technique is also referred to as metalorganic CVD (MOCVD).
In the microelectronics field where this technique of widely used, it is also commonly referred to as
organometallic vapor phase epitaxy (OMVPE). In the PACVD technique, the heating of the gas mixture
is accomplished by creating a high energy plasma that activates the chemical reactions at considerably

reduced temperatures as compared to the conventional CVD. In the case of LCVD techniques, the same
effect is achieved by using a laser beam to heat the gas volume or the substrate.

Deepak G. Bhat

GTE Valenite Corporation

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© 2006 by Taylor & Francis Group, LLC
Typical operating parameters for a conventional CVD process are shown in Table 35.1. Different
reaction chamber, and a system for the treatment and disposal of exhaust gases. Figure 35.1 shows the

35

-4

Coatings Technology Handbook, Third Edition

that with the increasing prominence of the composite materials in the advanced engineering components,
many more materials will be synthesized in the whisker and fiber forms for these applications.
As stated earlier, the conventional CVD calls for relatively high temperatures. This requirement imposes
certain limitations on the type of substrate that can be successfully used for deposition. Typically, most
ceramic materials, graphite, and refractory metals such as tungsten and molybdenum are found to be
quite suitable because of their high thermal and chemical stability in typical CVD process environments.
Steels have also been used successfully, but certain precautions must be taken for best results. For example,
most steels other than austenitic or ferritic steels undergo solid state phase transformation in the 700 to
800

°

C temperature range. This transformation is accompanied by changes in microstructure, physical
properties, and dimensions that could be detrimental for the coating or the component in the intended
application. In addition, the chemical stability of steel may be compromised in some CVD coating
operations, as in the case of tungsten deposition as a result of the reaction of steel with the fluoride gases.

FIGURE 35.2

Metallic compounds deposited by CVD. (A) Iridium-coated rhenium thrust chamber for liquid
rockets, 75 mm major diameter

×

175 mm length

×

0.75 mm wall thickness; (B) Tungsten crucible, 325 mm diameter

×

575 mm height

×

1.5 mm wall thickness; (C) Tungsten manifold, about 175 mm long. (Photographs courtesy of
Ultramet Corporation, Pacoima, California; reprinted with permission. Figure 2 of “A review of chemical vapor
deposition techniques, materials & applications,” by D. G. Bhat,

Surface Modification Technologies,

pp. 1–21, The
Metallurgical Society, 420 Commonwealth Drive, Warrendale, PA 15086.)
A
C
B

DK4036_book.fm Page 4 Monday, April 25, 2005 12:18 PM
© 2006 by Taylor & Francis Group, LLC