Satas D., Tracton A.A. (ed.). Coatings Technology Handbook

302

ALINA

Table

1

Friction

Data

by Materials

Coefficients of friction

Upper plate" Lowcr plate" Static Kinetic

Ice

Hi-T-Lube

Hi-T-Lube"

Lcctrofluor

604

Lcctrofluor

604P

M:lgllagold

Magnagold

Mag~~agold

Magnagold

Magnagold TFE

Magnaplate HCR

Magnaplate HMF

Nedox

SIF

2

Nedox

SIF

2

Nedox

SIF

2

Nedox SIF

2

Tufram

604

Tufram

H-2

Tufram

H-2

Tufram

H-2

Tufram H-2

Tufram

H-0

Tufram H-0

Tufram

H-0

Ice

Hi-T-Lubc

Stecl

Hi-T-Lube"

Glass

Teflon

Magnagold

+

Ni

Teflon

Steel

Nickel

Glass

Aluminum

Chromium"

Steel

Nickel

Titanium

P

Copicr paper

MOSl2

Hi-T-Lube

Graphite over paper

Magnagold

+

TFE

Magnaplate HCR

Glass

Aluminum

Teflon

Hi-T-Lubeh

Magnaplate HMF

Teflon

Glass

Steel

Teflon

Nedox SIF

2

Glass

Aluminum

Tufram

H-2

Glass

Aluminum

Tcflon

Tufram

H-0

Glass

Aluminum

Teflon

0.000

0.251

0.056

0.034

0.190

0.106

0.245

0.484

0.150

0.300

0.326

0.177

0.248

0.193

0.3 13

0.367

0.559

0.5

l8

0.304

0.264

0.260

0.22s

0.198

0.138

0.346

0.142

0.032

0.160

0.059

0.2s

1

0.212

0.30

1

0.103

0.179

0.137

0.429

0.17

1

0.203

0.377

0.134

0.249

0.180

0.25

1

0.121

0.000

0.217

0.049

0.034

0.172

0.089

0.21

1

0.357

0.123

0.246

0.259

0.1

S5

0.220

0.174

0.285

0.329

0.494

0.497

0.270

0.244

0.234

0.174

0.125

0.289

0.120

0.03

1

0.147

0.053

0.192

0.181

0.260

0.090

0.123

0.130

0.37

1

0.139

0.169

0.264

0.120

0.223

0. IS0

0.2 19

0.103

TRIBOLOGICAL SYNERGISTIC COATINGS

303

Table

1

Continued

Coefficients of friction

Upper

plate"

Lower plate" Static Kinetic

Tufram

L-4

Tufram

L-4

Tufram

L-4

Tufram

L-4

Tufram

R66

Tufram

R66

Tufram

R66

Tufram

R66

Aluminum

Chromium

Copier paper

Graphite over paper

Hard chromium

Hardcoated aluminum

MOS/2

Nickel

Steel

Tufram

L-4

Aluminum

Glass

Teflon

Glass

Tufram

R66

Aluminum

Teflon

Titanium A

Titanium

P

Teflon

Glass

Aluminum

Magnagold

Chromium

Nickel

Steel

Chromium

A

Aluminum

Magnagold

Nickel

Steel

Copier paper

Graphite over paper

Titanium

P

Teflon

Glass

Teflon

Hardcoated aluminum

MO92

Teflon

Chromium

Aluminum

Magnagold

Nickel

Titanium

P

Hi-T-Lube

Graphite over paper

Aluminum

Magnagold

+

Ni

Teflon

Nickel

Glass

0.184

0.353

0.256

0.142

0.162

0.148

0.329

0.133

0.4 13

0.6 I4

0.237

0.

I75

0.646

0.304

0.199

0.258

0.466

0.176

0.266

0.176

0.405

0.254

0.275

0.322

0.344

0.095

0.151

0.

I78

0.264

0.433

0.148

0.192

0.330

0.308

0.3

I7

0.493

0.254

0.245

0.349

0.377

0.675

0.269

0.723

0.

I27

0.

I73

0.294

0.189

0.

I30

0.

I49

0.1

1s

0.272

0.

I00

0.376

0.53

I

0.

I86

0.137

0.563

0.263

0.185

0.233

0.375

0.1 59

0.2 I6

0.

I49

0.356

0.2

10

0.259

0.302

0.304

0.078

0.

I21

0,157

0.220

0.4

I

x

0.

I20

0.174

0.253

0.267

0.279

0.410

0.2

18

0.225

0.247

0.308

0.607

0.269

0.553

0.

I

16

304

ALINA

Table

1

Continued

Upper plate“ Lower plate“

Coefficients of friction

Static Kinetic

Stcel

Steel

Stcel

Teflon

Tctlon

Teflon

Titanium A

Titanium

A

Titanium

A

Titanium A

Titanium

P

Titanium

P

Titanium

P

Titanium

P

Titanium A

Titanium

A

Titanium

P

Titanium

P

Chromium

Nickel

Magnagold

Nickel

Steel

Titanium A

Titanium

P

Hard chronium

Magnagold

+

Ni

Magnagold

Magnaplate HCR

Magnaplate HMF

Nedox

SF2

Tufram

H-2

Tufram H0

Tufram

L4

Tufram

R66

Tcflon

Steel

Nickel

Hardcoated aluminum

Glass

Aluminum

Steel

Magnagold

Hard chromium

Aluminum

Steel

Magnagold

Hard chromium

Alumium

Titanium A

Teflon

Titanium A

Tcflon

0.202

0.43

1

0.218

0.353

0.423

0.232

0.29

1

0.210

0.209

0.161

0.178

0.172

0.149

0.

I37

0.167

0.149

0.180

0.083

0.184

0.223

0.207

0.097

0.

I94

0.358

0.264

0.375

0.345

0.369

0.290

0.328

0.430

0.359

0.174

0.415

0.223

0.174

0.333

0.194

0.3

15

0.35

I

0.205

0.240

0.191

0.160

0.1

l4

0.167

0.154

0.120

0.

I27

0.138

0.131

0.149

0.070

0.1

57

0.190

0.183

0.097

0.177

0.3 l7

0.226

0.332

0.288

0.283

0.258

0.288

0.32

I

0.303

0.142

0.370

0.193

“A

superscrlpt “a” indicates additional polish after coatmg: a

“h”

Indicates

postbum~shing-comparable

to

hrcaking

In the surface.

3.

An average of five readings per test run.

4.

A

T.M.I. Slip and Friction Tester (model 98.5) was used, with a constant load

5. The materials and coatings were listed

in

Table

2.

6.

The friction tester used was the T.M.I. slip and friction tester Model

No.

98-5,

of

200

g.

using a constant 200 gram

load.

It

is

shown

in

Figure 2.

TRIBOLOGICAL SYNERGISTIC COATINGS

305

Table

2

Key to Materials and Coatings Listed in Table

1

Designation in

Table

1

Description

Aluminum

Steel

Titanium A

Titanium P

Glass

Teflon

Nickel

Hard chromium

Hard anodize

6061 T6 grade

(0.250)

thickness

1032 grade H32

(0.250)

thickness

6A1/4V

(0.250)

thickness

Vacuum deposlted at 10-5 torr,

2

pm

thickness, purity

99.99%

Tempered (0.250) thickness

White, virgin grade

(0.250)

thickness

Autocatalytic 6/8% phosphorus

(0.001)

Industrial grade (0.0003)

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

2

T.M.I. Slip and friction tester.

306

ALlNA

c

Figure

3

The

Taber

Abraser.

3.0

WEAR TESTING

Wear tests are difficult for most people to comprehend. However,

a

system that is consid-

ered a reasonably good standard is the Taber Abraser (Fig.

3).

This instrument requires

a panel

4

in. square, coated with the material that is being tested. It can vary loads (grams),

the number of cycles (generally

103-104),

and the type of abrasive wheel (either

CS-l0

or

CS-17)

being used.

After a set of conditions has been established, it is easy to use them as a standard

for new coatings, since there now is a basis for comparison.

The principle of this wear method is a weight loss of coating based on the degree

of wear.

Note the conditions and weight

loss

in Figures

4

and

5

for aluminum and steel,

respectively.

4.0

COATING FAMILIES

4.1

Polymer Coatings (Lectrofluor)

The properties that can be easily achieved using polymer or organic coatings are dielectric,

chemical corrosion, and radiation resistance; in addition, special organic coatings can be

used with food and pharmaceutical applications in compliance with regulations

of

the

U.S.

Food and Drug Administration.

All coatings are proprietary, since they are new developments, and specific nomen-

clature

(601,

604,

615,

611,

etc.) is used for identification.

TRIBOLOGICAL SYNERGISTIC COATINGS

307

TABER ABRASION (ALUMINUM)

WFIGHT

LOSS

=

mg.

per

10,000

Cycles,

?l7

wheel,

1000

gm.

load

20

30

40

!%

60

i

HARDCOAT ANODIZED (UN$EAlED)

PER

MILA4625

TYPE

HI,

CLAS

1

.MAONAPLATE

HCR

COATING

Figure

4

Weight

loss

following Taber abrasion for aluminum samples with various coatings.

TABER ABRASION (STEEL)

mg.10

20

30

40

50

80

70

80

90

100 110

120

130

11

~ ~

-

~~~ ~ ~

-

~-

~~

ELECTROLESS NICKEL

PER

MIL-C-26074 CLASS

1

(0.001

-

NO HEAT TREATMENT)

ma

ELECTROLESS NICKEL

PER

MiLC26074

CLASS

2

(0.001

WITH HEAT TREATMENT)

-

0.001

(GEN. MAGNAPLATE CORP.)

NEDOX CR+

0.001

(GEN. MAGNAPLATE CORP.)

I

Figure

5

Weight

loss

following Taber abrasion for steel samples with various coatings.

308

ALINA

Coatings can be applied by spraying, by dipping. or by an electrostatic powder

process.

In

most cases, a curing temperature will be in the range of 300-750°F will achieve

maximum surface hardness and minimize porosity. Polymer coatings normally range from

0.001

to

0.015 in.

in

thickness.

Salt spray resistance

of

these coatings is excellent: approximately 2000 hours (6

years in the atmosphere). The chemical resistance is the main property of the 60

1

coating.

which can withstand strong acids and alkalies at temperatures up

to

2000°F. The 604

material has similar resistance but can be utilized

in

food applications. The 615 is a tough.

durable coating

(D-80

durometer) that can withstand temperatures from -400 to 500°F.

and can also be used

in

food applications. The 61

1

coating, which has good release

characteristics, also is used in applications

in

the baking industry and comes in a variety

of

colors.

4.2

Magnesium (Magnadize) and Titanium (Canadize)

Since magnesium and titanium are widely used materials, especially in the field of aero-

space and computers, their users often are confronted with very severe problems.

A

system for hardfacing each material has been developed which is basically an

electrochemical process. The synergistic coating system is still far the best for a wear

application, however, and special fluoropolymers or dry lubricants are infused into the

hardfacing.

For

magnesium the synergistic coating is called Magnadize and for titanium

it is called Canadize.

For magnesium the thickness can vary from a minimum of 0.0002 in.

to

a maximum

exceeding

0.00

15

in. Normal application thickness is approximately 0.0005-0.00

I

in.

It

is more difficult to build up thickness for titanium,

so

the normal application

thickness is between 0.0002 and

0.0005

in.

A

typical application for Magnadize would be a magnesium engine mount for air-

craft. The entire mount would be hardcoated, and the gear spline would receive dry lubri-

cant to improve the efficiency of the part.

A

classic application for Canadizing is titanium hardware for aircraft. Such compo-

nents are anodized with an infusion

to

a thickness

of

0.0002-0.0004 in. to prevent the

titanium from seizing.

4.3

Titanium Nitride (Magnagold)

Since the introduction of titanium nitride to the industrial sector. coating companies have

been offering this service without sufficient knowledge of its engineering properties. The

coating was known

to

be extremely hard, and it was being applied to cutting

tools

exclu-

sively.

A

study of this coating material, however, revealed some interesting properties,

noted in Tables

3-5.

One of the unique features of the titanium nitride process is the uniformity

of

the

coating. This is critical for many applications involving missile, computer, and semicon-

ductor applications. Other excellent applications are found in the plastic extrusion industry

(which utilizes the superior release properties in molds and dies); the medical industry

(for coating delicate surgical instruments, and preventing solder adherence when special

heat treatments are employed in the complex multistep process).

In

this Magnagold process, a uniform coating. held

to

within a few millionths

of

an

inch thickness, can be applied safely to even the most critical, closest tolerance parts via

special cleaning fixturing mechanisms and techniques that enable the part

to

be rotated

TRIBOLOGICAL SYNERGISTIC COATINGS

309

Table

3

Some Physical Properties of Magnagold Coatings

Hardncss

R,

80-85

Chemical resistance to 30% concentrations of Virtually no attack

nitric and sulfuric acids

on

copper and steel

substrates at ambient tempcrature

Alkali resistance

Virtually no attack

Tabcr abrasion test, CS

IO

wheel,

1000

g load, Average weight

loss

>OS

mg

Coating thickness

1-3

km

Uniformity of thickness

15

X

IO-'

0.000015

in.

(max.)

Crystal lattice

Body-centered cubic,

a

=

4.249

8

Density 5.44 g/cm4

Thermal conductivity, callcmlsccPC

-0.162 (at 1500°C)

-0.167 (at 1600°C)

-0.165 (at 1700°C)

-0.136 (at 2300°C)

10,000

cycles

Coefficient of thermal expansion

X

10

''

cmPC 9.35 ?0.04 (at 25

-1

100°C)

Electrical resistivity

40 (at 27°C)

Thcrmonic emission work function

3.75 CV

Microhardness (Hu)

2050 kglmm' (load

100

g)

Table

4

Wettability of Various Metal Surfaces

Wettability metal Contact (Temperature/Condition)

cu

AI

Cd

Ph

Sn

Bi

Fe

CO

Ni

180"

126"

148"

136"

147"

135"

139"

102"

140"

147"

100"

132"

104"

-

70"

1

10"

(

1

100°C vac)

(

1

180°C vac)

(

1

130°C Ar)

(850- 1000°C vac)

(900°C Ar)

(450°C vac)

(350°C vac)

(370°C Ar)

(

1500°C vac)

(

1550°C Ar)

(

1560°C NH3)

(

155O0c vac)

(1

550°c vac)

(

1450- 1500°C

N,)

31

0

ALlNA

Table

5

Static

(S)

and Kinetic

(K)

Coefficients

of

Friction

for

Variously Coated Components

of

a

Panel Assembly

Upper panel

Lower panel

Steel

(4-8

pm in.

RMS)

Teflon

Steel

(4-8

MS)

S:

0.534

f

0.079 0.184

2

0.029

K

0.400

k

0.093 0.157

?

0.029

Magnagold

(4-8

RMS)

S:

0.218

f

0.028 0.161

2

0.014

K

0.194

f

0.030 0.114

k

0.017

360"

while traveling through the vapor stream. The process sequence is outlined in Figure

6;

a production setup appears in Figure

7.

Because the parts to be coated are rotated both radially and axially

within

the unique

ion bombardment chamber, there

are

no restrictions on shapes. In addition, all surfaces,

except clamp and fixture areas, are uniform in coating thickness. Normally, the thickness

ranges from

0.00003

and

0.0002

in., with final determination being edge sharpness and/

or

wear. (Load life is the ultimate criterion for the final decision.)

Since the condition of the substrate surface is a key element in the effectiveness of

any physical vapor deposition

(PVD)

process, General Magnaplate has engineered an

exclusive, proprietary predeposition surface preparation.

A

combination of specialty de-

signed equipment and chemical cleaning techniques prepares the component surface to

Figure

6

The Magnagold process sequence.

TRIBOLOGICAL SYNERGISTIC COATINGS

31

1

Figure

7

The

Magnagold production setup.

assure permanently interlocked anchoring of the “coating.” Conventional vapor deposi-

tion 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

X

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.

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.

Satas D., Tracton A.A. (ed.). Coatings Technology Handbook

Подождите немного. Документ загружается.