화학공학소재연구정보센터
Rheologica Acta, Vol.50, No.3, 221-229, 2011
Piezo rotary and axial vibrator (PRAV) characterization of a fresh coating during its drying
Using a piezo rotary and axial vibrator (PRAV) the viscoelastic properties of a fresh Al2O3 coating that is deposited on a well-chosen plate can be measured simultaneously during drying. There are three types of vibrations available to be excited and detected in their resonance modes, by measuring resonance frequencies f (k) and half-widths h (k), before and after coating as a function of time: axial vibration, bending vibration to get the evolving Young's modulus and rotary vibration to follow the viscosity increase during drying of the thin coating. This information is contained in the complex frequency shifts Omega(k) = 2 Delta f (k) /f (k) + i Delta h (k) /f (k) of the three vibration modes caused by the coating on the plate. A derivation of the relationships, their validation on Newtonian liquids and experimental applications carried out using the PRAV are given in the paper.