1：Experimental Design and Method Selection:

NCD films were grown using Microwave Plasma Enhanced Chemical Vapor Deposition (MPCVD) in methane/hydrogen/nitrogen plasma. Tribological tests were conducted under reciprocating sliding conditions with varying loads and cycles. Scaling analysis was used to study growth dynamics.

2：Sample Selection and Data Sources:

HPHT (110) single crystal diamond substrates (3x4x1.5 mm plates from Euro Superabrasives Limited) and Si(100) substrates were used. Films of thicknesses 2.2, 8, 10.5, and 22.5 μm were prepared with growth times of 32, 54, 73, and 130 minutes.

3：5 mm plates from Euro Superabrasives Limited) and Si(100) substrates were used. Films of thicknesses 2, 8, 5, and 5 μm were prepared with growth times of 32, 54, 73, and 130 minutes. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: MPCVD system (power 2.5 kW, pressure 80 Tr, temperature 1050–1100 °C), CETR UMT-2 tribometer, Si3N4 balls (REDHILL), AFM (Bruker MultiMode 8), SEM (Zeiss EVO MA-15 and Zeiss Merlin), stylus profilometer (Mahr Perthometer), micro-Raman setup (Renishaw inVia), XRD (Rigaku Ultima IV).

4：5 kW, pressure 80 Tr, temperature 1050–1100 °C), CETR UMT-2 tribometer, Si3N4 balls (REDHILL), AFM (Bruker MultiMode 8), SEM (Zeiss EVO MA-15 and Zeiss Merlin), stylus profilometer (Mahr Perthometer), micro-Raman setup (Renishaw inVia), XRD (Rigaku Ultima IV). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Films were deposited, thickness measured by mechanical fracture. Tribological tests: normal loads 0.5 and 2 N, displacement amplitude 1 mm, frequency 5 Hz, up to 72,000 cycles. Surface morphology analyzed with AFM and SEM, wear scars with profilometry, structure with Raman and XRD.

5：5 and 2 N, displacement amplitude 1 mm, frequency 5 Hz, up to 72,000 cycles. Surface morphology analyzed with AFM and SEM, wear scars with profilometry, structure with Raman and XRD. Data Analysis Methods:

5. Data Analysis Methods: Scaling exponents calculated from power spectral density (PSD) functions. Hertzian contact pressure calculated using method from Erdemir et al. Wear volumes and coefficients of friction analyzed statistically.