Acoustic emission analysis for monitoring tribological behaviors of steel coated with zinc phosphate/stearate for cold forging

The study investigated the tribological behaviors of zinc phosphate/stearate-coated steel in cold forging using acoustic emission (AE) analysis. Pin-on-flat linear reciprocating tests were conducted with varying cycles to monitor changes in friction coefficient and coating state. AE signals were analyzed using short-time Fourier transform (STFT), waveforms, and AE parameters such as count rate, energy rate, and root-mean-square (RMS). The study found that steel exposure led to peak count rates. As the steel area fraction increased, energy rate and RMS peaked due to reduced wear. The increase in AE burst signals caused by wear debris contacting the steel was also observed in this test.