*2.2. Experimental Methods*

The wear samples were cut into the samples to be processed (with a volume size of 20 × 30 × 6 mm3) using an electric spark machine (DK7732, Huadong Group, Hangzhou, China), and the samples were processed successively with waterproof abrasive paper of di fferent granularities to remove the traces of wire cutting. Then, an ultrasonic cleaner was used to clean the samples, thereby removing the residual oil and debris on the surface of the sample to achieve a smooth and clean surface.

A bionic strip specimen was fabricated using a solid-state pulsed Nd: YAG laser with a wavelength of 1.064 μm and maximum output power of 500 W. The processing schematic diagram is shown in Figure 1. The laser processing parameters are shown in Table 2.

**Figure 1.** The schematic diagram of laser bionic processing.



The sample was cut in the direction perpendicular to the incident direction of the laser using an electric spark machine. The cross-section was sequentially milled and polished. Pickling was carried out using a 4% nitric acid solution. Characterizations of the cross-section of the unit were carried out using an optical microscope (Zeiss, Axio Image A2m, Oberkochen, Germany). The microstructure of the unit and the substrate were observed using an electron scanning microscope (Zeiss, EV018, Oberkochen, Germany). The X-ray diffractometer (Rigaku D/Max 2500PC, Tokyo, Japan) was used for phase analysis.

Microhardness testing was performed on a microhardness tester (HVS-1000A, Beijing, China). The load was 1.962 N, and the holding time was 10 s. A schematic diagram of the hardness is shown in Figure 2.

**Figure 2.** The position of the hardness measurement points.

The tensile test was carried out on a hydraulic servo test machine (MTS 810, MTS Systems Corporation, Eden Prairie, MN, USA) at room temperature and the crosshead speed is 1 mm/s. Figure 3a shows the dimensions of the tensile specimen after laser bionic treatment. Three test specimens for each set were tested and averaged as the final result. After the test, the tensile fracture morphology for all samples were analyzed.

**Figure 3.** The bionic specimens used for (**a**) tensile and (**b**) wear testing.

Figure 3b shows a schematic of the wear sample after laser bionic treatment. The schematic of the reciprocating sliding wear testing machine developed by the laboratory is shown in Figure 4. During the experiment, the friction pair was fixed, and the sample located in the card slot was linearly reciprocated. The friction pair material is made of quenched gray iron (800 HV), the eccentric speed is 690 r/min, the wear time is 600 min, and the load is 100 N. All experiments were carried out at room temperature under dry conditions.

**Figure 4.** Schematic of the siding wear tester.

Before and after the wear test, the samples were cleaned with an ultrasonic cleaner, dried for half an hour, and then weighed before and after wear by an electronic balance (FA2400, Shanghai jinmin instrument equipment co. LTD, Changshu city, China); then, the weight loss was calculated. Each experiment was repeated three times, and the final results were averaged. Finally, the wear surface morphology was observed with a surface profiler (NT9100, Brock, Germany).
