+ All Categories
Home > Documents > Wayne D. Niemeyer

Wayne D. Niemeyer

Date post: 18-Dec-2021
Category:
Upload: others
View: 2 times
Download: 0 times
Share this document with a friend
36
Wayne D. Niemeyer Senior Research Scientist 40+ years of experience Scanning Electron Microscopy Webinar is being recorded Type your questions into the Questions box
Transcript

Wayne D. Niemeyer

• Senior Research Scientist

• 40+ years of experience

• Scanning Electron Microscopy

• Webinar is being recorded

• Type your questions into the Questions box

Case Studies of Corrosion Failures

Wayne D. Niemeyer

Senior Research Scientist

The Eight Forms of Corrosion

1. Uniform Attack2. Galvanic (2 metal) Corrosion3. Crevice Corrosion4. Intergranular Corrosion5. Pitting Corrosion6. Selective Leaching7. Erosion Corrosion8. Stress Corrosion

Fontana and Green, Corrosion Engineering, McGraw-Hill, Inc., ©1967, pp28-107

The Eight Forms of Corrosion

1. Uniform Attack2. Galvanic (2 metal) Corrosion3. Crevice Corrosion4. Intergranular Corrosion5. Pitting Corrosion6. Selective Leaching7. Erosion Corrosion8. Stress Corrosion

Case #1Catastrophic Corrosion Failure of

Stainless Steel Rods

Scenario: The steel rods for liquid fills were prematurely breaking while in an assembly line machine, causing the entire line to shut down. We need to determine the mode of failure and identify a potential cause(s) of the failure.

SEM Images – Fracture Face

.

.

Secondary Electron Images

Fracture Face – EDS Data

Element Weight % Weight % SigmaOxygen (O) 13.25 1.01Sodium (Na) 1.99 0.55Silicon (Si) 0.73 0.20Sulfur (S) 0.36 0.15Chlorine (Cl) 0.78 0.17Chromium (Cr) 20.42 0.49Manganese (Mn) 1.15 0.31Iron (Fe) 54.75 0.89Nickel (Ni) 6.57 0.41

Polished Cross Section of the Stainless Steel Tube

Fracture Site

Polished Cross Section Showing Typical Intergranular Corrosion

SEM BEI Composition Image

Epoxy Mount

Grain boundary corrosion

Polished Cross Section Showing Typical Intergranular Corrosion

SEM BEI Composition Image

Grain boundary corrosion

Polished Cross Section Showing Typical Intergranular Corrosion

SEM BEI Composition Image

23

4

Polished Cross Section Showing Typical Intergranular Corrosion

SEM BEI Composition Image

23

4

Polished Cross Section Showing Typical Intergranular Corrosion

SEM BEI Composition Image

Conclusions

• The fracture was caused by intergranular corrosion

• Minor sulfur and trace chlorine in the EDS data indicate sulfate and/or chloride corrosive agents

• The steel rod is very similar to a 304 series stainless steel alloy

• There are apparent chromium carbide precipitates in the grain boundaries, indicating improper heat treatment; thus making the alloy more susceptible to intergranular corrosion attack

Discussions with the Client• Problem #1 – The steel rods are supposed to be 316 alloy stainless steel, but

we determined probable 304 alloy. Their supplier gave them the wrong alloy! The 304 alloy is, in general, much more susceptible to intergranular corrosion than the 316 alloy. Replace any remaining rods with the correct alloy.

• Problem #2 – Apparently the rod is not heat treated properly to minimize chromium carbide precipitation. For future rod purchases specify heat treatment requirement and have the supplier provide certification records with each batch of rods.

• Problem #3 - The client uses an organic acid/strong oxidizer solution to clean the rods and recently increased the concentration. The organic acid is a known cause of intergranular corrosion on stainless steel alloys. Go back to original concentration or replace the cleaner with another solution that does not cause intergranular corrosion on stainless steel.

• We embarked on an in-depth investigation to determine the cause of an

unusual cratering problem on the interior coating of Draw & Iron (D & I)

aluminum beverage cans

• We discovered a surprising set of circumstances that led to a successful

resolution of the problem

Case #2

Acknowledgements

• Frank McDonough – Quaker Chemical,

Conshohocken, PA.

• Mike Shuster – Ball Packaging International,

Westminster, CO

Modern Microscopy, “Microanalysis of Craters in Organic Coating in Aluminum Cans”, February 2006

(https://www.mccrone.com/mm/microanalysis-of-craters-in-organic-coating-of-aluminum-cans/)

Cratering Defined

• The formation of small bowl-shaped depressions in a coating film.

• The depressions frequently have drops or bands of materials at the

center and raised circular edges.

• Common causes are:

– Gel particles

– Dirt

– Fibers

– Undissolved silicone

– Overspray

– Filter aid

– Oil droplets from air lines or machinery

Ref: “Coating Film Defects”, Federation of Societies for Coatings Technology, pp. 14-15, ©1994

Typical Crater in a Paint Film

Crater Debris

EDS Spectrum

https://www.slideshare.net/DaliaElGhayesh/can-manufacturing

SEM Images Aluminum Can Side Wall Crater

Coating

Crater Floor

Bridging + rounded edges = Corrosion!!

EDS - Qualitative Elemental Composition

C,O, Mg, Al, Ca, Mn C,O, Mg, Al, S, Ca, Mn

C,O, Mg, Al, Mn

Crater #1 Crater #2

Crater #3

SIMS Analysis

• Secondary Ion Mass Spectrometry

• Solid sample is bombarded with a beam of particles

(primary ions)

• Ions (secondary ions) are ejected (sputtered) from the

surface

• Secondary ions are collected and mass analyzed (mass

spectrometry)

• Capable of detecting all elements of the Periodic Table

with ppm detection limits

Cameca IMS 4f SIMS

Primary Ion Beam

Secondary Ions,Atoms, Electrons

+

+

+

+

+++

+

++

+

+

+

+

e -

e -

e -

e -

e -

e -

e -

e -

++

+

+++

+ +

+

++

+

++ +

+

++

+

+

+

+

+++

++

+ +

+

+

+

+

++

++

+

++

+

++

++

+

+

+

+

+

+

+

+

++

+

+ +

+

+

+

+

+

+

+

+

+

+

+

+

+

+

Secondary Ions, Atoms, Electrons

SIMS Sputtering Process

SIMS Technique

Mass Analyzer

Sample

Primary Ion Beam( O2

+ , O–, Ar+, Cs+, Ga+ )

SIMS Spectra from Crater Floor and Pit

B

B

Crater floor next to pit: boron ~ 20 counts Crater corrosion pit: boron ~ 2000 counts

Mass (amu) Mass (amu)

Seco

nd

ary

Ion

Co

un

ts

Seco

nd

ary

Ion

Co

un

ts

SIMS ION MAPS

Pit #1 Pit #2

Calcium

Boron

Iron

*ME = Metal Exposure

*

Let’s Piece this Together

• We found Ca, B, Fe in the aluminum can corrosion pits

• Quaker Chemical found abnormally high levels of Ca and Fe in the lubricant/coolant system during the problem time period.

• Production personnel observed sporadic color change in the lubricant/coolant indicative of the dye used in the cooling tower water.

• Borate salts, such as, amine borate are often used as corrosion inhibitors for iron piping in water systems.

• When the production personnel pumped out the lubricant/coolant during the change-over, they replaced a cracked heat exchanger used to circulate the cooling tower water.

• The cooling tower water was highly alkaline (not so corrosive to steel but very corrosive to aluminum).

• THAT’s IT!!! The cooling tower water was leaking into the lubricant/coolant system and causing the severe corrosion on the aluminum cans.

SEM Images from Simulation Tests

Fresh lubricant emulsion Fresh lubricant emulsion with cooling tower water added

Cooling tower water only

Requirements for a Successful Conclusion to this Difficult Problem

• Strong partnership between the vendor and the customer based on open communication, common goals, and mutual trust.

• Teamwork. The “vendor-customer-contract laboratory” team worked closely together with a strong sense of urgency, good project organization, and execution.

Wayne D. NiemeyerSenior Research Scientist

[email protected]• (630) 887-7100

Thank you for joining us. Questions?

UPCOMING WEBINAR

NEW COURSE

• the principles of operation

• basic and advanced imaging modes

• overall capabilities of AFM/SPM

• Hands-on training with a variety of samples

More Than Topography: What Else Can Atomic Force Microscopy Measure?

Tuesday, September 12, 2017 • 1:00 • Dalia Yablon, Ph.D.

Atomic force microscopy (AFM), famous for creating accurate 3D surface maps, is far more powerful than

a mapping tool. AFM can measure nanoscale properties in conjunction with topography – mechanical

properties, magnetic properties, electrical properties and optical properties.

Atomic Force Microscopy/Scanning Probe Microscopy

Wayne D. NiemeyerSenior Research Scientist

[email protected]• (630) 887-7100

Thank you for joining us. Questions?


Recommended