Construction and Characterization of TiN/Si(3)N(4) Composite Insulation Layer in TiN/Si(3)N(4)/Ni(80)Cr(20) Thin Film Cutting Force Sensor

The measurement of cutting force is an effective method for machining condition monitoring in intelligent manufacturing. Titanium nitride films and silicon nitride films were prepared on 304 stainless steel substrates by DC-reactive magnetron sputtering and plasma-enhanced chemical vapor deposition (PECVD). The effects of substrate negative bias and nitrogen flow on the surface microstructures of TiN film were investigated. The smoothness of the film is optimal when the bias voltage is −60 V. X-ray diffraction (XRD) analysis was performed on the samples with the optimal smoothness, and it was found that when the nitrogen flow rate was higher than 2 sccm, the titanium nitride film had a mixed phase of TiN(111) and (200). It is further revealed that the change of peak intensity of TiN(200) can be enhanced by nitrogen flow. Through atomic force microscopy (AFM), it is found that the stronger the intensity of the TiN (200) peak, the smoother the surface of the film is. Finally, the effect of different film thicknesses on the hardness and toughness of the TiN/Si(3)N(4) film system was studied by nanoindentation experiments. The nanohardness (H) of the TiN/Si(3)N(4) film can reach 39.2 GPa, the elastic modulus (E) is 480.4 GPa, the optimal toughness value (H(3)/E(2)) is 0.261 GPa, and the sample has good insulation performance. Linear fitting of the film’s toughness to nanohardness shows that TiN/Si(3)N(4) films with higher hardness usually have a higher H(3)/E(2) ratio.