Surface Corrosion and Wear Studies: Rapid, Automated, Quantifiable. Dr. Erik Novak Bruker Nano Surfaces Division

Transcription

1 Surface Corrosion and Wear Studies: Rapid, Automated, Quantifiable Dr. Erik Novak Bruker Nano Surfaces Division

2 Tribology and Corrosion are Costly When Uncontrolled Tribology: The science of the mechanisms of friction, lubrication, and wear of interacting surfaces that are in relative motion. Corrosion: The deterioration of a material by chemical or electrochemical reaction with its environment Quantification of these processes is essential for many industries: Automotive, robotics, data storage, petrochemical, medical device, MEMS, precision machining and more Combined loss to industry of over $400B annually BP estimated up to $40M/day from closing Alaska pipeline in 2009 Medical implants intolerant of any unexpected failures Hip joint wear pattern

3 Surface Wear July 3, Bruker Nano Surfaces Division Slide 3

4 Creating Worn Surfaces Wear can be created naturally Removed hips or other orthopedic parts Engine parts after use Brake pads Wear can be created artificially Rub two or more components together manually Use specialized test for one type of wear (such as toothpaste abrasion) Use generalized tool capable of many types of wear creation July 3, Bruker Nano Surfaces Division Slide 4

5 Universal Mechanical Tester (UMT) Machines Provide Quantitative, Flexible Tribology and Corrosion Capability Unsurpassed accuracy Servo-control of loads and positions Modular design Field upgrade of test and signal modules Gas or liquid environment supported Electrochemical capability Unsurpassed versatility Programmable loads, speeds, motions Temperature (-20 to 1000 C) Humidity (5-95 %RH) Vacuum (to 10E-6), gas environments ASTM and DIN standard test modes 7/3/2012 5

6 Automated Systems Are Specialized by Capability APEX Nano & micro mechanical test Thin films & nano materials 1µN to 10 N UMT-2 Micro Mechanical test Coatings, materials in general 1mN to 200 N UMT-3 Macro mechanical test Lubricants, Ceramics and Metals 0.1 N to 1 KN 7/3/2012 6

7 Stribeck Analysis Is Used for Characterizing Lubricants Directly generate Coefficient of Friction (COF) vs. Velocity (mm/min) Identifies Lubrication Capability 7/3/2012 7

8 Friction Vs. Force is Crucial to Many Applications Accurate determination of functional performance and asperity increase leading to spikes in friction 7/3/2012 8

9 Motion Path Must Reflect the Specific Application Use Case Sliding modes Reciprocating Oval sliding Double-elliptical sliding Triple-elliptical sliding Sliding frequency F x =0, F y =0.5 F x =0.5, F y =0.5 F x =1, F y =0.5 F x =1.5, F y =0.5 F r = F x /F y Track pattern Sliding distance per cycle /mm /3/2012 9

10 Characterization of Wear and Corrosion 7/3/

11 3D Topology Provides Many Tools for Quantification Volume of pits/scratches Bearing ratio Roughness Defect Quantification S Parameters 3D extension of R parameters to better characterize surface texture Quantify skew, kurtosis, peak density, slopes, bearing area, volume 20 initial parameters, with proposals to increase >30 ISO adoption is complete Power spectral density Quantifies spatial frequency content Very good for determining tooling characteristics

12 Comprehensive Surface Measurement Allows Understanding Wear The regions of wear on a surface are identified and quantified using analyses such as Bearing Ratio Peak areas that erode first are quantified Load bearing surface is identified Valley areas that would contain lubricates, etc. are quantified. 12

13 Accurate Wear Studies Require Area- Based Volume Measurements Pin and Ball on Disk Studies Quantify material characteristics with wear studies and quantify material removal in terms of volume Negative, positive and missing volumes are evaluated 13

14 Corrosion Studies Benefit From 3D Feature Finding 14

15 2D Stylus Systems Can Provide 3D Metrology Mature technology with over 40 years of continual innovation Exceptional ease of use and <0.5 nm repeatability! DektakXT Surface Profiler 7/3/

16 3D Microscopes Provide Flexible, Accurate Quantification for These Processes Microscope-based systems for 3D surface and film thickness measurement nm-level accuracy and repeatability Up to 14mm field of view Up to 100 µm/sec focus scans >10mm vertical range <0.2 µm lateral resolution Diffuse or specular surfaces Hundreds of thousands of surface points Flexible Analysis Configurations to meet any need Applications from food products and paper to MEMS and microoptics 2006 Veeco Instruments Inc.

17 Key Considerations for Corrosion and Tribology Sampling At least 10 parts (20 preferred) Large areal coverage Resolution Should be 10X higher than your goal Make sure it is real (relates to your setup) Repeatability Should be 10X higher than your detection goal Reproducibility Experiment well controlled Automation / Operator independence Accuracy Can you verify against a standard? Can you verify against another known technique Cannot assume old method is accurate just because it s been around forever! July 3, Bruker Nano Surfaces Division Slide 17

18 Tribology Study of Cutting and Drilling Surfaces 2006 Veeco Instruments Inc.

19 Drill Bit Examination Examine surface properties of bits of varying material/coatings drilling the same surface High speed steel, TiCN, SiC, TiN bits used to drill into 6mm anodized aluminum plate Head, inside surface, and forward surfaces examined throughout the process Many parameters examined to obtain meaningful data

20 HSS Surface Degradation Over course of 30 uses, material redeposited on surface significantly affects topology Radii of curvature, edge quality were unaffected Str High Speed Steel Inside Surface Bearing Rat Htp (nm) Str # Times Drilled Bearing Ratio Htp

21 Drilling Application Example: Cross material characterization Drill 30 holes using same setup, same machining and plate SiC bit showed least material redeposition, HSS the most Edge chipping, radius of curvature changes minimal for low use TiCN HSS TiN SiC 7/3/

22 3D Microscopes Quantify Processes and Determine Tool Degradation Prior to Further Use Characterize machining components such that problems are detected before any parts enter production Maximize lifetime and quality during the production phase for these components Most common items examined: Surgical blades Saws Razors Drill bits Grinding and lapping surfaces One Fortune 100 customer says that bad tooling costs them >$100M per year in failures

23 Razor Blade Tribology Razors Worn By: Daily use for 3 weeks 50 cycles on dry, fibrous material Examined cutting surface (edge) and those that contact the skin (small flat) Over 3 week period contact surface Rq increased by approximately 2X

24 Advanced Visualization Can Be As Important as Quantification 7/3/

25 Razor Cutting Edge Measurements Cutting surface average linewidth showed slight changes with use Standard deviation increases due to chipping Roughness also increased steadily Noticeable wear on surface as well Wear State of Blade RMS Roughness Cutting surface (µm) Average Linewidth of Cutting Surface (µm) New Cycles Cycles weeks use weeks use Std Deviation Linewidth of Cutting Surface (µm)

26 PEEK (Polyetheretherketone) Wear Study 2006 Veeco Instruments Inc.

27 Metrology Application Example 3D Microscope Quantifies Wear PEEK simulation of hip joint wear Measure undisturbed map Wear material and fixture for second measurement Determine volume of wear scar automatically 7/3/

28 3D Optical Profiling Accurately Measures the Worn Area Surface was worn repeatedly until 1mg of material was removed Top image shows sphere with wear scar Bottom image shows same surface but with spherical form removed July 3, 2012 Slide 28 Bruker Confidential Information Copyright 2011, Bruker Inc. All Rights Reserved

29 Software Automatically Calculates Worn Volume 1mg of PEEK removed Calculated PEEK density is then 7.9x10 8 µm 3 /mg Matches well with average density of 7.6x10 8 µm 3 /mg Repeatability better than 2 parts in 10 9 >100X better than gravimetric methods for small wear 29

30 Wear Study Steel Hip Cup Unworn Surface Sa <10nm Worn 100K Cycles Sa >2000nm 7/3/2012

31 Data Subtraction Allows Quantification of Change 7/3/2012

32 Feature-Finding Software Identifies and Quantifies Pits >50nm threshold >0.01mm 2 7/3/2012

33 Corrosion Studies of Metal Coupons July 3, Bruker Nano Surfaces Division Slide 33

34 Corrosion Metrology Surface changes over time can be both global and localized Global changes, such as rusted areas, area easily modeled and can be tested using bulk techniques such as resistivity Localized changes, such as pitting, are difficult to model and can cause catastrophic failure in short periods of time Experiments range from salt water baths for petrochemical industry to slight atmospheric or contamination in MEMS To accelerate experiments, we exposed surfaces to dilute H 2 SO 4 One aluminum coupon and 22 different surface texture regions on a GAR strip were examined Four of the 22 surface regions studied for corrosion. Surface roughness is 2, 8, 16 and 63 microinches moving from left to right.

35 Aluminum Coupon in Corrosive Environments Roughness changes from 1.3 to 3.5 µm

36 Corrosion Analysis: PSD Analysis Shows Texture Changes Mid spatial frequency content increases Surface overall far more random X PSD Uncorroded 30 min Spatial Frequency (lines/mm)

37 GAR Strip Corrosion Studies Show Little Effect From Initial Finish Corrosion with different starting surface finish type and level examined Overall rougher surfaces did not corrode significantly more in static environment Some initial defects seen to foster pitting and corrosion

38 Long Term Corrosion Measurements Showed Greater Effect From Initial Surface Finish Examined various surface finishes for rate of corrosion over longer time period Similar Trends on increasing roughness and randomness of the surface Rougher surfaces corroded to greater degree PSD (mm nm^ Y PSD of surface finish Uncorroded 7 hours corroded 14 hours corroded 21 hours corroded Spatial Frequency (1/mm)

39 Subtracting Measurements Highlights Corrosion Seed Points Easy way to study dynamic processes Visual or automated examination of surface differences Calculate volumes, areas, relative statistics on user-defined regions Here 13 pits are >250nm, > 200 total pixels

40 Case Study: ASSESSING CORROSION UNDER IRON SULFIDE DEPOSITS AND CO 2 /H 2 S CONDITIONS Courtesy: Carlos Menendez, Baker Hughes Corporation Corrosion 2011, Houston, Texas

41 Introduction to the Problem of UDC Need to establish a new testing methodology under which UDC attack could be defined for a set of sour conditions without the presence of corrosion inhibitor Differentiate impact on corrosion of various deposits like commercial, synthesized and precipitated in situ FeS 41

42 Optical Profiling Used to Assess Mass Loss Coupons Blank Synthesized FeS, Stoichiom (50 µm deep areas) FeS reagent #1 FeS reagent #2 Precipitation in situ 42 (200 to 500 µm deep pits)

43 Mass Loss Corrosion Rates Can be Calculated Vs. Various Conditions FeS Type Corr. Rate (mm/y) A 0.1 B 0.2 C 0.2 D 3.1 E 4.1 F 6.0 G 0.7 3D Microscope Data Compares Well to EIS measurements Optical profiling provides one of many valuable tools to assess corrosion.. 43

44 Accurate, Flexible Systems Enable Advanced Corrosion and Tribology Studies Automated Material Testers Wear Hardness Corrosion Modular design supports many experiments Comprehensive 3D Metrology Solutions Cost Effective Platform Choices Automated, operatorindependent measurements Comprehensive, ISO compliant Analyses

45 Bruker Offers Specialized Webinars On Different Topics July 3, Bruker Nano Surfaces Division Slide 45

46 Thank You! Questions? Erik Novak Contact Info: Bruker Website: July 3, Bruker Nano Surfaces Division Slide 46