1：Experimental Design and Method Selection:

The study used laser surface texturing (LST) with a Nd:YAG laser to pretreat Nb substrates, followed by BDD film deposition via hot filament chemical vapor deposition (HFCVD). The design aimed to enhance coating adherence by modifying surface topography and removing oxides with laser cleaning.

2：Sample Selection and Data Sources:

Nb plates (size 50×100×1 mm3) were used as substrates. They were polished with sandpaper and ultrasonically cleaned in alcohol and deionized water.

3：List of Experimental Equipment and Materials:

Equipment included a Nd:YAG laser system (wavelength 1064 nm, pulse length 20 ns), HFCVD system, SEM, XRD, Micro Raman spectroscopy, contact angle goniometer, and Rockwell indentation tester. Materials included Nb substrates, diamond powders (grain size

4：2-5 μm), methane, hydrogen, and B(OCH3)3 for boron doping. Experimental Procedures and Operational Workflow:

Substrates were textured with the laser at varying single pulse energies and scanning spacings, followed by a laser cleaning step to remove oxides. They were then ultrasonically abraded with diamond powder suspension, and BDD films were deposited via HFCVD under controlled conditions (CH4/H2 ratio

5：5%, H2 flow 800 sccm, substrate temp ~800°C, filament temp 2000°C, pressure 5 kPa, time 8h). Characterization involved SEM for morphology, XRD for composition, Raman spectroscopy for film properties, contact angle measurements for surface energy, and Rockwell indentation for adhesion testing. Data Analysis Methods:

Data were analyzed using SEM images, XRD patterns, Raman spectra, contact angle software (JC2000D), and qualitative assessment of Rockwell indentation morphology to evaluate adherence.