Combustion Pressure Sensors Using C-axis-oriented Zinc Oxide Thin Films Prepared on Inconel Substrates

Abstract

C-axis-oriented zinc oxide (ZnO) thin films were prepared on Inconel substrates by rf magnetron sputtering technique. The ZnO film characteristics were evaluated under pressures of 10.0 to 300.0 MPa and frequencies of 0.1 to 30 Hz at room temperature. The deviation from the linearity of charges with pressures for the ZnO films was within 0.52 % of a full scale at 300.0 MPa, which indicated a good linearity between 10.0 and 300.0 MPa. Furthermore the ZnO films were evaluated under combustion pressure in a single-piston 90 cc engine rotating at 1900 rpm. The waveform of the ZnO films was similar to those of a commercial sensor. It is demonstrated that the ZnO films have a good possibility as combustion pressure sensor elements.