View source for Nanoindentation sample preparation for Al


[[Category: SOP]]

The following is an SOP for the preparation of cast aluminum alloys samples for nanoindentation testing.

=Loss Prevention=
*Safety glasses are required to work in polishing labs at Michigan Technological University.
*Be mindful of the polishing machines. There are pinch points when moving the head and the grinding pads could cause abrasions.
*The air hose in the polishing lab is strictly for drying samples.
*EDM produces Ozone- keep machine closed during operation

=Procedure=
#Mark part with a marker where future cuts will be made
[[File:Autopolisher2.jpg|150px|thumb|right|Figure 1. Autopolisher in Polishing Lab]]
#Cut samples from part using edm (electrical discharge machining) to minimize subsurface deformations
#*Cutting settings
#**Current 3A
#**Voltage 4kV biased voltage
#**Feed rate .4mm per minute (speed through material)
#**Enter code (Gcode) to determine cut
#Mount the samples
#*[http://sop.mse.mtu.edu/index.php?title=Sample_Epoxy_Mounting See Sample Epoxy Mounting SOP] 
#Grind the testing surface manually using 600-grit SiC paper (Hudson)
#*When the marking is gone, the epoxy layer should be removed (Roughly 5 minutes)
#*Lubricate disk with water
#Grind the testing surface using 800-grit SiC paper (Hudson)
#*Polish for 2 minutes with a pressure of 20N or 5lb
#*Lubricate disk with water
#Grind the surface using 1200-grit SiC paper (Hudson) using an auto-polisher(shown in figure 1) for 3 minutes with 20N load
#*Fully load the auto polisher (3 samples) to maintain an even force on the samples
#*Lubricate disk with water
#Polish samples with 3μm diamond paste polish for 10 minutes with a 20N load on a disc reserved for this purpose.
#*Use Red lube to lubricate the disk. '''Do not use water'''.
#*To apply diamond paste, Rub the paste into the disk with a '''gloved''' fingertip while the wheel spins around 100-200RPM.
[[File:100X .05um partA 1.jpg|150px|thumb|right|Figure 2. A380 aluminum with .05um polish under 100X magnification]]
#Polish samples with 1μm diamond paste polish for 10 minutes with a 20N load on a different disc reserved for this purpose.
#*Use Red lube to lubricate the disk. '''Do not use water'''.
#*To apply diamond paste, Rub the paste into the disk with a '''gloved''' fingertip while the wheel spins around 100-200RPM.
#Polish samples with .05μm Aluminum oxide polish for 5 minutes with a 40N load on a disc reserved for this purpose.
#Inspect surface under an optical microscope to ensure that the surface is well polished.
#*For nanoindenation, the testing area should be smooth under 100X magnification
#*If surface is too damaged, It needs to be resurfaced starting with the 600 grit paper