Amorphous SiO2 interlayers for deposition ofadherent diamond films onto WC-Co inserts
(State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering,
Shanghai Jiao Tong University, Shanghai 200240, China)
Shanghai Jiao Tong University, Shanghai 200240, China)
Abstract: Amorphous SiO2 (a-SiO2) films were synthesized on WC-Co substrates with H2 and tetraethoxysilane (TEOS) via pyrolysis of molecular precursor. X-ray diffraction (XRD) pattern shows that silicon-cobalt compounds form at the interface between a-SiO2 films and WC-Co substrates. Moreover, it is observed by transmission electron microscope (TEM) that the a-SiO2 films are composed of hollow mirco-spheroid a-SiO2 particles. Subsequently，the a-SiO2 films are used as intermediate films and chemical vapor deposition (CVD) diamond films are deposited on them. Indentation tests were performed to evaluate the adhesion of bi-layer (a-SiO2 + diamond) films on cemented carbide substrates. And the cutting performance of bi-layer (a-SiO2 + diamond) coated inserts was evaluated by machining the glass fiber reinforced plastic (GFRP). The results show that a-SiO2 interlayers can greatly improve the adhesive strength of diamond films on cemented carbide inserts; furthermore, thickness of the a-SiO2 interlayers plays a significant role in their effectiveness on adhesion enhancement of diamond films.
Key words: hot filament chemical vapor deposition (HFCVD); diamond film; WC-Co substrate; interlayer; adhesion