Key points in sample preparation:

1、Cutting

Aluminum and aluminum alloys have low hardness and are prone to deformation. The cutting rate and feed rate of the cutting blade should be reduced during cutting. Silicon carbide cutting blades are generally recommended for cutting.

                                            Silicon carbide resin cutting wheel

2、Mounting

In most cases, general-purpose phenolic hot mounting resin is sufficient for mounting aluminum and aluminum alloys.

It is best to use slow-curing epoxy cold mounting resin for aluminum sheets, foils and electrolytic polishing specimens that are not pressure-resistant.

If electrolytic polishing is required, the sample should be exposed from behind the mounting resin to serve as a contact point during electrolytic polishing.

                                                                                                                   Universal hot mounting resin

                                                                                                           MC003 Vacuum-free clear cold mounting kit

3、Grinding and polishing

•  ● Pure aluminum is very soft and prone to mechanical deformation and scratches; when grinding and polishing, abrasive particles can easily embed into the surface of the material. Starting from rough grinding, coarse particles should be avoided as much as possible. It is recommended to start with finer silicon carbide sandpaper, such as 400#/600# for rough grinding. For larger aluminum alloy castings, you can start with 320# sandpaper. The pressure during grinding should be as small as possible.
•  ●  Diamond polishing liquid must be used to remove deep scratches when polishing aluminum and aluminum alloys.
•  ●  If the water solubility of the sample is not clear, use alcohol-based diamond suspension and alcohol-based lubricant for polishing.
•  ●  The abrasive should not be too thin or too much, which is easy to form a gray oxide film on the surface of the sample.
•  ●  If diamond particles are found to be pressed into the surface during polishing, the time for silicon dioxide fine polishing can be extended.
•  ●  Electrolytic polishing is only suitable for pure aluminum or deformed aluminum alloys, not for cast aluminum alloys, because cast aluminum alloys have many different phases.

The above recommended parameters are taken from: Preparation method of 30 mm aluminum alloy sample with 250 mm working plate on automatic grinding and polishing machine Smoothneer-6.