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Experimental studies for bearings degradation monitoring at an early stage using analysis of variance

Zarour D., Meziani S., Thomas M.

Diagnostyka

2018

Vol. 19, No. 4

81--87

This work presents a procedure for bearing degradation monitoring at an early stage. The analysis of variance (ANOVA) coupled with Tukey’s test is used to single out the suitable parameters to follow the fault size evolution ranging from 50 µm to 150µm. The Tukey's criterion is adopted in this case to study the ability of time and frequency indicators. The rotational speed, centrifugal load and fault size are considered as independent variables while the time and frequency indicators are taken as dependent variables. The experiments are performed on bearings having a fault on outer race. Based on the results of this study, the Kurtosis and Skewness show a good ability to assess the evolution of degradation in the bearings at an early stage. The paper discusses the weakness of the time and frequency indicators.

Compositional analysis of silicon oxide/silicon nitride thin films

Meziani S., Moussi A., Mahiou L., Outemzabet R.

Materials Science Poland

2016

Vol. 34, No. 2

315--321

Hydrogen, amorphous silicon nitride (SiNx:H abbreviated SiNx) films were grown on multicrystalline silicon (mc-Si) substrate by plasma enhanced chemical vapour deposition (PECVD) in parallel configuration using NH3/SiH4 gas mixtures. The mc-Si wafers were taken from the same column of Si cast ingot. After the deposition process, the layers were oxidized (thermal oxidation) in dry oxygen ambient environment at 950 ºC to get oxide/nitride (ON) structure. Secondary ion mass spectroscopy (SIMS), Rutherford backscattering spectroscopy (RBS), Auger electron spectroscopy (AES) and energy dispersive X-ray analysis (EDX) were employed for analyzing quantitatively the chemical composition and stoichiometry in the oxide-nitride stacked films. The effect of annealing temperature on the chemical composition of ON structure has been investigated. Some species, O, N, Si were redistributed in this structure during the thermal oxidation of SiNx. Indeed, oxygen diffused to the nitride layer into Si2O2N during dry oxidation.