Hysitron UBi1 Nanoindenter Operating Procedures

Transcription

1 UW Nanomech Lab 1 Hysitron UBi1 Nanoindenter Operating Procedures

2 UW Nanomech Lab 2 If at any time you are unsure about something, encounter a problem, or require the use of an indenter tip that is not currently mounted, please contact the system administrator for assistance. The current system administrator is Gabe grchow@u.washington.edu Phone: (707) Table of Contents WORDS OF CAUTION... 3 PREPARING THE HARDWARE AND YOUR SAMPLES... 4 FIRST STEPS... 5 Z-AXIS CALIBRATION... 6 DEFINING SAMPLES... 8 IMAGING INDENTATION SETTING UP THE LOAD FUNCTION AND PERFORMING A SINGLE INDENT PIEZO AUTOMATION SETTING UP AN AUTOMATED METHOD FOR INDENTATION INDENT ANALYSIS SCRATCH TESTING X-AXIS CALIBRATION SETTING UP A SCRATCH LOAD FUNCTION AND PERFORMING A SCRATCH AUTOMATED SCRATCHING SHUTDOWN PROCEDURES TROUBLE SHOOTING... 32

3 UW Nanomech Lab 3 Words of Caution 1. Do not leave the lamp on when it is not needed. 2. Always keep an eye on the tip position in the acoustic chamber as you move around with the x-y-z stage controls. Make sure that the tip will not crash into anything. 3. Tested surfaces have to be smooth enough or the tip can be damaged easily and you will get poor indentation results 4. Do not use computer while it is busy performing a function such as an approach or during any sort of automated testing. Doing so may cause the computer to freeze.

4 UW Nanomech Lab 4 Preparing the hardware and your samples 1. If the machine is totally off, do not attempt to turn it on. Contact the system administrator. 2. Consult the log book first to see if anyone else is currently using the indenter. If not, write your name, the date, and the starting time for your testing into the book. 3. Check your samples to make sure they are clean, smooth, and not tilted. When performing a session with multiple samples, only proceed if they are around the same height (less than 1 mm difference). If they are significantly different in height, analyze them one at a time. 4. Open the Acoustic Enclosure and put the sample(s) onto the stage. The sample stage is magnetic. It is recommended that you mount by gluing a magnet to the bottom of your samples. Simply taping samples to the surface can be done, but only if absolutely necessary. If this is done, the bottom of the sample must be flush with sample stage (eg. no double stick tape). CAUTION: Do not touch the transducer assembly or the indenter tip while mounting the samples 5. Look on the main control unit and check that the knobs have the following settings: Low pass filter: 1000 Hz Displacement Gain: 100 Microscope Feedback: 1000 Display Gain: Zero the front panel meter by manually adjusting the coarse knob to less than 0.01.

5 UW Nanomech Lab 5 First steps 1. Start from the windows Start menu and open the TriboScan Program. The program takes a few minutes to initialize as it zeroes the stages. Once started, the main window should look similar to this: 2. To create a workspace, go to the top left of the screen and click the down arrow next to Default workspace. Select New Workspace and save as any name you desire. 3. Turn on the fiber optic light next the UBi1 computer (the V-lux 1000 unit) to illuminate the stage.

6 UW Nanomech Lab 6 Z-axis Calibration 1. Z-axis calibration should be done at the beginning of each session. Go to the calibration tab in the main window and click on the system calibrations sub tab. Location of microscope feedback software setting and calibrate execution button 2. Adjust the microscope gain to 100 in both the software and hardware. This MUST be done for proper calibration. Software: In the calibration tab, go to the system calibration sub tab and look at the System Setup Front Panel Settings. Change the Microscope Feedback Gain to 100. Hardware: Physically adjust the Microscope Feedback Gain to 100 on the main control unit with the knob. 3. Now look at where it says Transducer Calibrations. Under indentation axis, click Calibrate Cal Air Indent button

7 UW Nanomech Lab 7 4. The software will switch to the Load Function tab where you can click Cal Air Indent 5. A dialog box will ask Is the load function set up correctly, click Start 6. A dialog box will ask Re-zero front panel meter on TriboScope controller. Re-zero the controller manually on the main control unit. 7. A dialog box will ask to set the Displacement Gain to 100 and microscope feedback gain to 100. Both these should already be set correctly from earlier, but double check anyways. Click OK and the z-axis calibration will run. 8. Once the test is finished, it will ask if you want to keep the air calibration data, click Yes 9. A dialog box will ask to re-zero the controller once again and return the microscope feedback gain to Perform both of these tasks on the main control unit, then click OK 10. A graph will appear with a fitted function of the Electrostatic Force Constant as a function of displacement. If the fit is reasonable such as the picture below, you can close the curve fit plot window. If the fit is lousy, double check that the microscope feedback and displacement gain were set to 100 in both the software and hardware controls during the calibration. Redo the z-axis calibration and if the result is still poor, contact the system administrator for assistance. Example ESF vs Displacement Plot 11. Go back to the calibration tab and the system calibrations sub tab. Change the microscope feedback gain back to 1000 under the front panel settings. CAUTION: It is very important to double check that the microscope feedback gain has been changed back to the value of 1000 in both the software and hardware before proceeding. (Steps 9 and 11)

8 UW Nanomech Lab 8 Defining Samples 1. Go to the Sample Navigation tab of the software. It will bring you back to the display seen when the software was first started. Stage controls are in the top right quadrant of the screen. Stage controls and X-Y lock toggle 2. By default, the x-y stages are locked before any samples are defined. Click the bubble next to X-Y Safety DISABLED so that it turns red to unlock x-y movement. 3. The 3-axis movements are done by clicking and holding various parts of the blue reticule graphic. The separated column on the left is for Z-axis control. For example, clicking and holding position 6 will lower the Z-axis at the fastest speed. To lower at a slower speed, click closer to the bolded blue median line. To raise the stage, click above the median line. Stage controls guide 4. X-Y controls are similarly done by clicking and holding various positions on the X-Y diagram. For example, holding position 2 will increase the Y position at fastest speed. Holding position 5 will increase X position at slow speed. 5. It is now time to define your sample(s). While looking into the acoustic chamber, adjust the x-y position so that the lighted area is centered over a corner of the sample. Next, lower the z-axis until the corner and a flat portion of the sample area are in optical focus. You may need to adjust the x-y position while doing this.

9 UW Nanomech Lab 9 CAUTION: The bottom stage comes into focus at ~32 mm in Z-height, never go above this value. Use your sample thickness to estimate when your sample should come into focus. For example, a 1 mm thick sample will come into focus at ~31 mm. The focus point is always several millimeters before the point of tip contact. Keep a close eye on the tip as it descends and make sure that it does not crash into the stage or sample surface. Do not work with samples that have a large height difference to one another as the transducer and tip could easily bump into the thicker sample as it tries to focus onto the thinner one. 6. With the corner in focus, click on New sample at the sample controls located in the bottom left quadrant of the screen and name the sample. Then click on Pos. Add so that the software saves the location of this corner. New sample and Pos. Add button locations 7. Now, navigate to another corner of the sample using the x-y controls. Re-focus the image at the next corner (if necessary) by adjusting the z-axis slightly. With the next corner in focus, click Pos. Add once again. 8. Repeat step 7 until all corners have been defined. 9. You should now see a colored outline of your sample shape next to the navigation window where the stage overview is displayed. It will also be seen in the samples control region next to the Pos. add and New Sample buttons. 10. Repeat steps 5-9 until all samples have been defined. 11. Once all samples are defined, it is easy to navigate around the samples by right clicking on either the actual live image, the stage overview (above the x-y safety buttons), or the sample window in the bottom left. 12. If you will be performing automated tests on all samples during this session without imaging the surfaces, navigate to a spot close to the center of each sample (by right clicking or by using the x-y controls) and perform a quick approach on each. This is necessary to determine the exact Z-height of each sample before automation. Each quick approach will take several minutes. Once the quick approaches are done, skip ahead to the Setting up an automated method section. 13. If you will be imaging the surface first before performing tests, a quick approach is not necessary at this time. It will be performed in the next section. 14. Now is a good time to save your workspace. This is done by using the drop down menu in the upper-left. It is the same one that was used earlier to create a workspace, except this time, select Save Workspace.

10 UW Nanomech Lab 10 Imaging 1. From the Sample Navigation tab of the software, navigate to a spot on the sample where imaging is desired by using the x-y controls or by right-clicking. 2. Switch to the Imaging tab of the software 3. Turn off the fiber optic light now since it is not necessary for SPM imaging. 4. Look at the imaging controls. Set the appropriate parameters you would like. The default values work well for most samples. They are: Scan Rate: 1 Hz, Tip Velocity: 20 µm/s Scan Size: 10 µm Setpoint: 2 µn Integral Gain: 496 Vertical Scanning: Off (unchecked) Imaging controls settings 5. Re-zero the front panel manually by adjusting the coarse knob to a reading < Approach the surface by clicking the approach surface button on the imaging toolbar in the upper left. It is found directly below the word Engage. Image control toolbar - approach button 7. Once the sample has been approached, click the green Go button on the image toolbar to start scanning. 8. The four images should now start updating as the scan progresses. The images on the left side are topographical images in the forwards (top) and backwards (bottom) directions. The images on the right are gradient images in the forwards and backwards directions. 9. The lower right quadrant displays the image data regarding the current scan lines and

11 UW Nanomech Lab 11 height histograms. Adjusting values in here can make the SPM images look much better by changing the color mapping. The easiest option is to hit the Auto button. However sometimes it may need manual adjustment by using the blue sliders. Scanning data display 10. If you wish to save a scan image, in the imaging tab, go to the Image drop down menu and click on Capture File Name. Select the folder where you want to save your image, write the file name, and click ok. During the scan, click on the camera icon on the image toolbar next to the stop button. The image will be automatically saved to the folder you selected once the scanner has completed the next full pass over the scanning area. You can analyze the saved images afterwards with the software Triboview

12 UW Nanomech Lab 12 Indentation Setting up the Load Function and performing a Single Indent 1. While imaging the surface, on the image toolbar, there is an option to perform a single indentation. However, before indenting, there are a few things that need to be setup. 2. Make sure that the Mode at the top of the screen is set to Indentation 3. You need to setup the loading parameters for the indentation. Switch to the Load Function tab in the software and make sure you are on the Quasi sub tab. Load Function tab with default loading criteria 4. The default load function is an open loop indent with a 10 second load/unload time. In this configuration, there is no force feedback therefore this load function is not commonly used. 5. Many former users of the indenter have adopted a 10:5:10 load control function for use with their characterization. This specifies a load control indent with a 10s loading time, 5s hold time at maximum load, and a 10s unloading time. This load function is highly recommended for all characterization purposes. 6. To change the load function from the default settings, go to the File menu and click on Open Load Function. Click and load the Load_Control_10s_5s_10s.ldf file to load the 10:5:10 function.

13 UW Nanomech Lab 13 Standard load function with important parameters circled 7. After loading the function, the parameters that may require some attention here are: Pre-Load: This should be equal to or greater than the scanning setpoint. Default is 2µN Lift Height: This is the distance the tip is raised over the surface before the indentation begins. This should be equal to or greater than the surface roughness. Default is 10 nm and that value works fine for most polished samples where roughness is typically very low. Peak force: Set the maximum indentation force. CAUTION: Do not change any of the other parameters unless you have permission to! 8. If your work requires the use of a specific load function, a custom load function can be created by adding segments and manipulating the segment parameters. If this will be done, please let the system administrator know so that the function can be checked to be within the limitations of the instrument. 9. Once you have the load function set up, switch back to the Imaging tab of the software. 10. Find a place on the sample that you would like to indent on and center it in the image area. 11. On the image toolbar, click on the Test button to start indentation. Image control toolbar Test button 12. A dialog box will ask if the load function is setup correctly. Click OK to proceed with the indentation. While the indent is running a real time monitor window show you the progress of the indent. This will be in the form of a red line traced with blue dots. The blue dots are real time data coming back, and the red line is the intended load

14 UW Nanomech Lab 14 function. If the blue dots do not follow the red line, than you need to adjust the load control feedback gains until they follow the red line as closely as possible. Please contact the system administrator for assistance with this problem. Real-time display during indentation

15 UW Nanomech Lab 15 Piezo Automation 1. To properly characterize the properties of a sample, multiple indents with different forces are usually necessary. Piezo automation performs an automated set of indents with varying force on the imaged surface. 2. The first step is to find a suitable area for the automated indents. Ideally, the entire imaging area should be smooth and as flat as possible. 3. Next, switch to the Load Function tab of the software and make sure that the load function is setup properly for the automated indentations that will be performed. Do not worry about the Peak Force setting for now as Piezo Automation will change that accordingly. 4. Switch to the Automation tab of the software and click on the Piezo Automation sub tab. On this screen, there are several important selections to make: Save scan: scan and save the imaging area after the indent array is complete. This is suggested. Stay in Contact: Set whether the tip will stay in contact with the surface after the array is complete. It is highly suggested that you do not do this since you will most likely be away from the machine during the automation process. Piezo automation settings 5. Next, you must choose the number of indents and spacing between the indents in both the x and y directions. It is suggested that you make the spacing between the indents several times the size of the indent.

16 UW Nanomech Lab 16 Piezo automation settings 6. It is suggested that the time delays Before 1 st Indent be set to 180 sec, and Between Indents to 120 sec. 7. Once everything is setup, click on Run Piezo Automation to start the indent array. You will be asked if the load function is set up properly, click yes. You will then be asked for a directory to store the files. A third prompt will ask what the filenames will be. Type in a descriptive name that includes the tip, sample, and loading range. For example: Berk_Al_1000uN_500uN. 8. The final menu allows you to control the loading range. The top box shows the number of indents in the array. The left box allows you to choose the maximum load of the first indent, and the right box allows you to choose the maximum load of the last indent. The bottom box shows you the change in maximum load between each indent. See the pictures below. It is recommended that you start with the highest load first and end with the lowest. After you have chosen the appropriate values click continue to start the array. Load selection for piezo automation test 9. As a general rule, always watch the first process in an automation before leaving the computer to make sure everything goes okay.

17 UW Nanomech Lab 17 Setting up an automated Method for Indentation 1. If you have multiple samples mounted and/or are interested in characterizing a single sample at multiple locations, using an automated Method is much more flexible than the Piezo automation function. The main drawback is the lack of sample imaging prior to the indentation process therefore this is only recommended for samples with low surface roughness and exceptional surface quality. 2. Methods are defined by patterns, groups, and positions. A Group is a set of user defined positions on the sample surface. At each position in the group, an indentation pattern will be performed. Each method can only have one group and one pattern associated with it. However Methods can be chained to each other to start successively giving the user the ability to perform different types of indentation arrays at different areas. Even if the same indentation pattern will be used on all samples and at all locations, it is still recommended that each sample has its own Method setup. 3. Methods can only be performed on defined sample areas and samples where a quick approach has been executed. Make sure these tasks have been complete before proceeding. 4. Switch to the Automation tab of the software and click on the Methods sub tab. 5. Create a method by clicking on New Method and name it. 6. A dialog box saying The pattern in method <method name> is not set may come up. Just click OK as the pattern will be setup later on. 7. Change the Base File Name and Drive & Directory to an appropriate filename and location that you want to save the data to. Make sure that the Method type is Indent. Methods tab Region to create a new method circled

18 UW Nanomech Lab Next click on the Patterns sub tab found on the far right side next to the New Method button. 9. You can now setup the indentation array that will be followed. The most common is to use a grid (just like the piezo automation test), but other choices are available such as the Circle for a circular pattern. Click on either one and set the appropriate spacing parameters between indents. Then click Create to save the pattern while naming it accordingly. Patterns setup 10. Next click on the Position sub tab found directly underneath the Patterns sub tab. Here you will define the positions where the indentation pattern from above will be performed. Start by clicking New and name the group of positions. Navigate to a position where you would like to indent by right clicking in the sample window in the bottom left or by using the x-y controls. Once the position is centered in the live image window, click on Add above and the position will be saved. Navigate to another position where you would like to perform the indentation pattern and this time click either Add Above or Add Below. If Add Above is selected, this position will be executed prior to the first one. The opposite is true if Add below is selected. Continue adding positions until all desired positions for indentation have been saved. Groups and Positions setup region 11. Go back to the Setup sub tab found directly above the Patterns sub tab. The patterns and groups created by the user need to be associated with the method. Go to the Patterns subsection and select the saved pattern using the up and down arrows. The pattern should be displayed on the right. It is not recommended to Maintain contact within patterns.

19 UW Nanomech Lab 19 Patterns subsection 12. Now go to the Positions subsection and select the bubble Indent pattern using positions in. Select the correct group name using the up and down arrows. Positions subsection 13. Click on Load Function and the Load Function Setup window will appear. Click on Select load function and select the standard Load_Control_10s_5s_10s.ldf file or a custom function file that you have saved. Bubble in the option Adjust peak load while keeping segment times constant. Adjust the start and ending load to the desired values. It is recommended that the highest load is first and the lowest load is last. Click OK when done with these parameters. The correct loading task at each position should now be defined in the text under Load Function. If it is incorrect, go back into the Load Function Setup window and adjust the values accordingly. CAUTION: Do not select any of the other bubbles in the Load Function Setup window.

20 UW Nanomech Lab 20 Load function button and Load function setup screen 14. If you want to save SPM images of the surfaces before and after each test, click on the Imaging button. This will bring up the Imaging Setup window. Click on the On checkboxes to enable Pre method imaging and/or Post method imaging. Bubble in imaging applied to each event in a method. The scanning parameters will not need to be altered since methods should only be applied to samples with good surface quality! Close the Imaging Setup Window when finished.

21 UW Nanomech Lab 21 Imaging button and Imaging setup screen 15. If you are working with multiple samples, repeat steps 5-14 to create a separate method for each sample. 16. Once methods have been setup for each sample, you can chain the methods together so that they start successively. To do this, go to the bottom of the screen where it says When method is complete and check the box labeled Perform Method. In the area to the right, select the name of the 2 nd method to start. Now go back to the top of the screen where it says Method Name and select the name of the 2 nd method. Go down to the bottom and once again check the box to perform another method and select the 3 rd method. Continue doing this until all methods have been chained together. Selection for chaining methods together 17. Click Start Method to begin the automation process. 18. As a general rule, always watch the first process in an automation before leaving the computer to make sure everything goes okay.

22 UW Nanomech Lab 22 Indent Analysis 1. The indent Analysis window will open at the end of an indent, or go to Analysis tab in the software. 2. If your indentation data did not load automatically, click the Open button on the analysis toolbar and find the file where the data was saved. Analysis toolbar Open button 3. Ensure that the Unloading Segment is correct in the parameters listed on the right side. For usual cases, the unloading segment is set to Click Execute Fit and the hardness and modulus numbers will be generated and displayed at the top right of the screen. Analysis tab, unloading segment selection and execute fit button 5. To plot multiple curves at once, go analysis toolbar and click the Plot multiple curves button. When the next window comes up, click on Add Curves. When the Select Data Files to Plot window appears, highlight the desired curves, click Add, and then click OK. The curves will now be plotted.

23 UW Nanomech Lab 23 Multiple curve plotting and analysis 6. To analyze multiple curves, in the multiple curves plot, click Mult. Cur. Ana. You will then be asked to name the file to save the data into. Name the file and continue. The multiple curve analysis window opens and you will have the option of loading other data sets to compare, see picture below. Modulus and Hardness data display window

24 UW Nanomech Lab 24 Scratch Testing X-axis calibration 1. Start by switching the software mode to Scratch near the top center of the screen. Switching to Scratch Mode 2. Just like for Z-axis testing, we need to calibrate the X-axis before performing any scratches. Click to the Calibration tab of the software and go to the System Calibrations sub tab. 3. Make sure that the Scratch Axis transducer constants are the same as the values provided by the hysitron constants sheet. The values are: Load Scale Factor: mv/mg Displacement Scale Factor: mv/µm Imaging Position: µm Electrostatic Force Constant: µn/v 2 Plate Spacing: µm Displacement Offset: µm The calibration constants sheet can be found in the front sleeve of the logbook binder. Scratch Calibration Page. Places to adjust the constants circled 4. Once all the constants have been entered, click on Calibrate and the software will switch to the Load Function tab. Make sure that the Scratch Axis Calibration.scf file is loaded and displayed in the top left of the screen under the File menu.

25 UW Nanomech Lab 25 Scratch calibration load function page. Filename position circled 5. Click on Cal Air Scratch to begin the calibration process. A real-time plot should pop up showing the tip progress through the scratch from -5 to 5 µm. At the end of the scratch, a popup box will ask if you want to keep the calibration data, click yes. 6. After clicking yes, 4 graphs will display. The one of importance is the Lateral Force vs Time plot. Make sure that all of these values fall within a 10 µn range such as the figure below. If they do not, then go back to the calibration page, double check the constants, and repeat the calibration. If the lateral force range still exceeds 10 µn, contact the system administrator for assistance. Example of a good calibration. Lateral force is within a 8 µn range.

26 UW Nanomech Lab 26 Setting up a Scratch Load Function and Performing a Scratch 1. To perform a scratch, you will need to define your samples and approach the surface for imaging first. These processes are outlined in the Defining samples and Imaging sections. 2. Once you have approached the surface, perform a scan to make sure that the surface is smooth and without craters or artifacts. CAUTION: This step is important because the lateral force transducer is very fragile. Any large obstacles in the scratch path may momentarily cause a spike in the lateral force leading to damage! 3. It is now time to create a scratch load function that will be used in the test. Switch to the Load Function tab in the software and find the Scratch sub tab if it does not direct you there automatically. 4. There is no adopted standard for nano-scratch testing therefore you will need to build your own function for your specific application. There are a few types of general functions that will be primarily used. They are constant force scratches and ramped force scratches. Each type can be in the positive (bottom to top) or negative (top to bottom) directions. The directionality becomes important if you are using a tip that is not axis-symmetric such as the Berkovich or cube corner. By going to the File menu and selecting Open load function, you will see that there are a few of these types of functions already saved. It is highly suggested that you modify one of these general functions and then save it with a customized name instead of trying to build a function from nothing. 5. For example, let us build a load function for an 8 µm long ramped force scratch in the negative direction with a load range from 0 to 500 µn. First, go to the File menu and select open load function. Load the ramp_force_scratch_neg_dir file since it most closely resembles what we will be doing. The function loaded describes a 45s 10µm open loop ramped force scratch from 0 to 1000 µn. We will need to make a few adjustments. First, adjust the Control Feedback type to Load Control to enable force feedback. This option is always recommended unless exact scratch depths are required (displacement control will be used in that case). Next, change the Max Displacement and Min Displacement to +4 and -4 µm respectively since we want an 8 µm long scratch. Finally, adjust the Peak Force to 500 µn. The default scratch time of 45s can be adjusted by clicking on each segment on the graph itself (they will highly red when correctly selected) and adjusting the Segment Time accordingly.

27 UW Nanomech Lab 27 Scratch load function setup 6. The example above covers just one of the many scratches that the machine is capable of. The main ideas behind setting up other functions are the same. The most important parameters are the control feedback selection, the maximum and minimum displacements, and the peak force. CAUTION: When selecting the values above, the following considerations must be made: The maximum scratch length is 12 µm, but it is recommended that you stay within 10 µm for the best results (-5 to 5 µm in the max and min displacement boxes). The lateral force transducer will be damaged if the lateral force exceeds 2000 µn. Also, scratching with large force can easily damage the indenter tip. The lateral force generated by your scratches will depend on the specific sample properties, but as a general rule, keep the Peak Force under 1000 µn. Contact the system administrator for permission if you need to go higher. 7. With an appropriate scratch load function configured, it is now time to perform the scratch. Switch back to the Imaging tab and click on the Test button on the image toolbar. It is the same button used to conduct a single indentation test, but since the software has been switched to Scratch mode, a scratch is performed. Image toolbar Test button 8. A popup box will ask if the load function is setup correctly, click Start. The test will now begin. 9. After the test is finished, a popup box will ask where to save the scratch data. Select an appropriate location and file name. The software should switch to the Analysis tab

28 UW Nanomech Lab 28 and show the scratch results afterwards. 10. It is highly recommended that you scan and save an image of the scratched area. These images are the only way to analyze the final scratch depth and are very important in wear characterization. The saved topographical images can be analyzed in the Triboview software. 11. The analysis tab does offer a few valuable tools. One such tool is the ability to account for the gradient or tilt of the sample. In bottom right graph of Lateral Displacement vs Time, click and drag the two red lines so that first region of the plot is bound. See the figure below. Then click Tilt Correction Scratch Analysis. Region to set red bars to highlighted. 12. Once you have corrected for the tilt, you can find the friction from the sample by clicking on the friction button. Note that the friction value is not truly the coefficient of friction of the sample, but also includes the plowing resistance. Thus, the deeper the indent, the higher the friction value will be. For the most accurate friction values, use shallow scratches. The friction plot displays the results for all segments by default including those where the tip is held in place and/or where no normal force is applied. The actual scratching segment is the only one of interest (typically segment 3).

29 UW Nanomech Lab 29 Example friction plot

30 UW Nanomech Lab 30 Automated Scratching 1. There is no piezo automation for scratches, however scratches can be automated by using methods. CAUTION: Due to the inability to scan the surface prior to scratch, it is strongly recommended that you do not use scratch methods. This ability should only be used for samples that are polished to optical quality and where you are certain that the sample is immaculate at all points on the surface! 2. Setting up a scratch method is very similar to creating the indentation methods. Please read that section first to get a good background on the procedure. 3. First, create a new method and select the method type to be Scratch. Set the filename and directories accordingly. CAUTION: Remember, each sample should have its own separate method. Make sure that the method type is Scratch 4. Create a new pattern and select positions for your scratches by using the patterns and positions sub tabs on the right hand side. The pattern generation and position selection processes can done by following the similar procedure in the indentation methods section (Pg. 18, steps 8-10). When creating a scratch pattern such as a grid, keep in mind how long your scratches will be and adjust the separation distance between points accordingly. 5. Switch back to the main Setup tab and associate your desired pattern and positions group with your method in the Patterns and Positions subsections. This process is also exactly the same as the process for indentation methods (Pg. 18, steps 11-12). Remember, each method can only have one Pattern and one Group associated with it. Therefore, if you will be performing different types of scratches, each scratch type must have its own method. 6. Click on Load Function and select the appropriate scratch load function. 7. Decide whether you would like to save images. If so, click on the Imaging button and configure accordingly. 8. If you have multiple scratch types or are scratching on multiple samples, you will need to set up methods for each scratch type and for each separate sample. 9. Once all scratch methods have been configured, chain them together in the same way indentation methods are chained together. (Pg. 19, step 16) 10. Click Start Method to begin the method. 11. As a general rule, always watch the first process in an automation before leaving the computer to make sure everything goes okay.

31 UW Nanomech Lab 31 Shutdown procedures 1. If you were imaging or performing a piezo automation, disengage the tip from the sample surface by switching to the Imaging tab and selecting the Withdraw button on the imaging toolbar. It will be greyed out if you have already withdrawn from the surface. Imaging toolbar Withdraw button 2. If you were performing an automated method, the tip should have withdrawn automatically, but double check in the Imaging tab to make sure that the button is greyed out. 3. Once withdrawn, switch back to the Sample Navigation tab and use the z-axis controls to lift the tip up to a Z-height of ~1-3 mm. An acceptable Z-height for sample removal 4. Open the acoustic enclosure and remove any samples that you have inside CAUTION: Make sure that you do not touch or accidentally bump the transducer or tip while removing samples. 5. Turn off the fiber optic light if it is on 6. Close out of the software by clicking the x in the top right corner. A popup will ask if you want to quit Triboscan. Click Yes. 7. A popup will ask if you want to save the workspace. Click Don t save. 8. The software will take a few minutes to exit as it resets all of the stage positions. 9. When the software is done closing, hit ctrl-alt-del on the keyboard and lock the computer. 10. Go to the log book and write the finishing time of testing, what kinds of samples you tested, what kinds of tests were done, and if anything out of the ordinary occurred. It is very important to record any slight problems that happened and what adjustments you might have made to solve the problem (things such as raising the setpoint to help your scan). These changes are sometimes saved in the software and the next user needs to be aware of such changes.

32 UW Nanomech Lab 32 Trouble shooting 1. If the tip detects excessive force because it has contacted something, manually swirl the indenter (top of the pole) z-axis knob clockwise and lift the tip to at least 1 mm above the point of contact. Reactivate the z-axis motor and start over. 2. If lose contact during imaging, stop it and click disengage button. After it finishes, click engage button and try again. You can also try re-zeroing the controller by going to the Engage menu from the Imaging tab and selecting Re-Zero the Controller. If trouble persists, consider using a slower scanning speed and a higher set point.