We have contacted a famous local company -- Luoyang Weixin special equipment CO. LTD., which has varieties of materials. We sent the request to the company in the form of an email, and soon received a response from the sales department. They recommended a wear-resistance and corrosion-resistance material - 4Cr14Ni14W2Mo that can guarantee the strength of the valve and the flexibility of the switch.
   And they said that if we are interested, they can use a cutting machine to cut one part of the raw materials (figure 1) and send it to us for research. When the person who contacted me in the company intercepted me, I went to the company to get the materials and had a friendly conversation with him. Figure 2 is the material after being cut and polished.

   After getting the material, we used the knowledge of materials science to study the surface of it with a magnifying glass. Because the material itself is non-toxic and harmless, it is not dangerous to directly observe it with hands. After that, it was stored in a box.