Tribological reaction accompanying friction and wear of silicon nitride containing titanium nitride

Effect of humidity in atmosphere gas, air, or argon, is investigated for the tribochemical reaction in Si3N4 - 23 percent TiN-Si3N4 - 23 percent TiN sliding contact system using a pin-on-plate type testing machine by reciprocal movement of pin against plate. An examination is also conducted on Si3N4-Si3N4 couple in comparison with the above system. The experimental results have shown that the wear rate decreases with increasing humidity, and the wear property is somewhat improved by adding a suitable amount of TiN to Si3N4. Reaction products formed on the interface under the sliding contact are analysed by using EPMA and XPS. It is confirmed that SiO2 (or TiO2) is produced on the surface during friction and wear, and the amount of SiO2 (or TiO2) increases with the increase of humidity. Formation of NH3 caused by development of tribochemical reaction on friction surface is examined by a spectrometric study using Nessler's reagent. The results show that the formation of NH3 is connected directly with the amount of SiO2 (or TiO2), and that three types of formation rate are observed depending on the humidity.