Researches on friction force between valve made of tial and its guide made of phosphorous bronze

A lightweight valve can be one made of steel but with a drilled stem. Another one can be made of TiAl alloys and its stem can be full or drilled. Lightweight valve can be also ceramic one made of Si3N4. Such valves can mate with guides made of cast iron or of phosphorous bronze in varying conditions in their common contact zone. The aim of researches has been to measure friction force in contact zone between valve stem made of TiAl alloy and its guide made of phosphorous bronze, in the absence of oil. The conditions of room temperature and of the atmosphere pressure have been used during experiment. Mentioned researches have been provided in tester, which design has been presented in the article. The loading of contact zone has varied periodically during serie. The displacement and acceleration of valve and the force during its impact into seat insert have been measured during tests. Additionally the sound level has been measured, either. Tests have been provided for different frequency of driving force. Obtained results of researches has been shown in the article. In all cases the measured sound level have been equal 94 dBA, when sound level of laboratory environment has been equal 40 dBA. Values for coefficient of friction between valve stem and its guide can change from 0.12 to 0.16 and decrease almost linearly with increasing of loading frequency. Values of dry friction coefficient between valve stem made of TiAl alloy and coated by chrome and its guide made of phosphorous bronze can be smaller up to 17% than values obtained in case of valve stem coated by nc-WC/a-C:H mating with a guide made of cast iron.