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1

Improved Methodology to Evaluate Abrasion Resistant Coatings

ByMuni Ramakrishnan PhD

Stephen BowditchA.W. Chesterton Company

2

Highlights

• We carried out a study to characterize andclassify our portfolio of wear resistant coatingsmeant for aggressive wear conditions.

• We utilized two test methods. We optimizedthe parameters to reduce the data scatter andimprove reliability.

3

Abrasive Wear in Industry

• Pumps

• Mixer Agitator Blades

• Pipelines

• Valves

• Chutes

• Wear Plates

4

Types of Abrasive Wear

• Two body - sliding

• Three body wear - grinding or crushingapplications

• Dry and Wet

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Factors to Consider When Specifying a Coating

Moderate, severe and extreme abrasion• Key parameters:

– Particle size / shape

– Particle hardness / density

– % solids suspended in media

– Media type (fluid / gas & make up)

– Temperature of exposure

– Velocity of flow

– Angle of impingement

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Goal

• Goal of this study is come up with a viable ranking method forrelative wear characterization of coatings.

• Current portfolio of products have broad classification – good,better, best – need for tighter ranking and classification.

• Utilize tests / develop test methods that are relevant tocoatings used in very aggressive environments.

7

Test Methods for Evaluation

• ASTM G 75

– Slurry abrasion

• Jet Abrader

– Dry abrasion

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Slurry Abrasion Test Video

9

Typical Wet Slurry Study Plots

Departure -10%

Correlation 82%

0.0

20.0

40.0

60.0

80.0

100.0

120.0

0 1 2 3 4 5 6

Cu

mm

ula

tive

Mas

s Lo

ss (

mg)

Time (hrs)

0.0

50.0

100.0

150.0

200.0

250.0

300.0

350.0

0 1 2 3 4 5 6

Cu

mm

ula

tive

Mas

s Lo

ss (

mg)

Time (hrs)

Departure -33%

Correlation 89%

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Variables Noted in ASTM G75

• Sample preparation

• Frequency of sand changes

• Cam lifter block in equipment design

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Old Sample Prep Method -Sample Coated on Metal

Post Sample Run

12

New Method - Molded Sample

Post Sample Run

13

Run Without Changing Sand for 6 Hours

0.0

50.0

100.0

150.0

200.0

250.0

0 1 2 3 4 5 6

Cu

mu

lati

ve M

ass

Loss

(m

g)

Time (hrs)

Departure -17%

Correlation 100%

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Frequency of Sand Changes

Picture of fresh sand Picture of sand after 2 hour run

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Runs Changing Sand Every Two Hours

• Example 1

0.0

50.0

100.0

150.0

200.0

250.0

300.0

0 1 2 3 4 5 6

Cu

mu

lati

ve M

ass

Loss

(m

g)

Time (hrs)

Departure -3%Correlation 100%

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Runs Changing Sand Every Two Hours

• Example 2

0.0

50.0

100.0

150.0

200.0

250.0

300.0

350.0

0 1 2 3 4 5 6

Cu

mu

lati

ve M

ass

Loss

(m

g)

Time (hrs)

Departure -3%Correlation 100%

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Test Chamber

Jet Abrader Test

Sample Set Up

80 Grit Brown Aluminum Oxide

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Jet Abrader Test

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Jet Pressure vs Volume Loss

@ 90° Angle

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0 10 20 30 40 50 60 70 80 90 100

Vo

lum

e L

oss

, mL

Pressure, PSI

Estimated Velocity, ft/sec185179172166160145126

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Volume Loss vs Time

0.0000

0.1000

0.2000

0.3000

0.4000

0.5000

0.6000

0.7000

0.8000

0.9000

1.0000

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

Vo

lum

e L

oss

, cc

Test Duration, min

50 PSI

60 PSI

70 PSI

80 PSI

90 PSI

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Angle of Impingement

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0 10 20 30 40 50 60 70 80 90 100

Vo

lum

e L

oss

Angle of Impingement

Angle of Impingement vs Volume Loss - 50 psi - 1 min

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90° 75° 60° 45° 30°

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Test Data

1 2 3 4 5 6

Initial

Weight (g)40.5189 41.9094 40.6969 50.632 42.954 45.498

Final

Weight (g)39.6773 41.0759 40.0268 49.815 41.887 44.604

Weight

Change (g)0.8416 0.8335 0.6701 0.817 1.067 0.894

Volume

Change (cc)0.3117 0.3087 0.2482 0.3026 0.3952 0.3311

Result

Average

Volume

Loss (cc)

0.32 Standard Deviation 0.0476 COV (%) 15.06%

Typical Past Jet Abrader Results

Product A

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Optimized Jet Abrader Results

Product A

Test Data

1 2 3 4 5 6

Initial

Weight (g)41.3080 39.7565 37.3077 38.9990 41.0665 39.1144

Final

Weight (g)40.5878 39.0280 36.5946 38.2808 40.3332 38.3587

Weight

Change (g)0.7202 0.7285 0.7131 0.7182 0.7333 0.7557

Volume

Change (cc)0.3386 0.3425 0.3353 0.3377 0.3448 0.3553

Result

Average

Volume

Loss (cc)

0.34Standard

Deviation0.0072 COV (%) 2.10%

Product B

Test Data

1 2 3 4 5 6

Initial

Weight (g)40.2796 41.7135 39.9311 42.2325 39.9514 42.3563

Final

Weight (g)39.0726 40.5229 38.6969 40.9724 38.7080 41.1233

Weight

Change (g)1.2070 1.1906 1.2342 1.2601 1.2434 1.2330

Volume

Change (cc)0.5029 0.4961 0.5143 0.5250 0.5181 0.5137

Result

Average

Volume

Loss (cc)

0.52Standard

Deviation0.015 COV (%) 2.05%

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Conclusions of Study

• Optimization is possible

• Reliability and Consistency of Data

• Additional variations to G 75 test

– Change abrasive media and concentration

– Vary fluid type

– Test different materials used in abrasion protection

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