Construction and Characterization of TiN/Si3N4 Composite Insulation Layer in TiN/Si3N4/Ni80Cr20 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/Si3N4 film system was studied by nanoindentation experiments. The nanohardness (H) of the TiN/Si3N4 film can reach 39.2 GPa, the elastic modulus (E) is 480.4 GPa, the optimal toughness value (H3/E2) is 0.261 GPa, and the sample has good insulation performance. Linear fitting of the film’s toughness to nanohardness shows that TiN/Si3N4 films with higher hardness usually have a higher H3/E2 ratio.

Analyses the Character of GaAs Photocathode by Diffraction Curve from Spectrophotometer

Transmissivity and reflectivity of GaAs photocathode get from spectrophotometer are measured and analyzed according to various wave bands, so that the corresponding optics parameter is obtained. The typical optics parameter of various GaAs photocathode has been summarized. For blue-light extension photocathode, the diffraction peak will be close to ultraviolet wave band from the reflection curve. The thickness of Active layer film and optimal Si3N4 film on the GaAlAs layer have been acquired. The experimental and analyzed results have shown that the Si3N4 film on the GaAlAs layer should be about 1000A when the the GaAs photocathode got the optimum performance.The thickness of Active layer film should not be too thick to escape of electron and too thin to transfer of photon-electron. The experiment shows that the spectrophotometer can analyze epitaxial material and assist the manufacture of GaAs photocathode.

Mechanical Properties of Nanocomposite TiN/Si3N4 Films Synthesized by Ion Beam Assisted Deposition (IBAD)

Nanocomposite coatings of TiN/Si3N4 have been prepared by ion beam assisted deposition (IBAD): simultaneous sputtering of Ti and Si targets and film bombardment by N2+ ions at 1000 eV. The Si/Ti ratio in the film varies from 0 to 0.9. The coatings are composed of amorphous Si3N4 and TiN nanocrystals with grain size of several nanometers. Such nanocomposites exhibit improved mechanical properties in comparison with TiN or Si3N4 deposited under the same conditions. The nanoindentation hardness of TiN/Si3N4 film at the Si/Ti ratio of 0.3 reaches a maximum of 42 GPa, compared with 22 GPa for TiN and 18 GPa for Si3N4. The wear resistance of AISI 52100 steel coated with these nanocomposite coatings is increased about three times.