Monitor Electroless Plating Of Ni-P Film On Quartz Surface And Adsorption Behavior Of Ice Film By Piezoelectric Sensors

Quartz crystal microbalance (QCM) is a chemical sensors which is highly sensitive tothe mass change onto electrode surface. Compared with other techniques, it provides a uniquemethod for observing in situ events, in which changes can be monitored in real time with highsensitivity, so it has a wide range of applications. This paper first introduces the overview ofthe development about the piezoelectric sensors in recent years. We carried out the followingresearch works.1) Real time monitor electroless plating of Ni-P film on quartz surface by an electrode-separated piezoelectric sensorThe kinetics related to an electroless Ni-P deposition on quartz surface was monitored byan electrode-separated piezoelectric sensor (ESPS). It was shown that the mass changesduring the initial grease removing and quartz coarsening process followed an exponentialdecay and linear decrease models, respectively. The corrosion rate of quartz increased withincreasing concentration of HF+H2SiF6and solution temperature. The presence of non-ionicsurfactant OP blocked the corrosion rate. The initial Ni-P plating process consisted of fourstages: an induction period, an acceleration period, a deceleration period and a stationaryperiod. When the temperature was increased from40to48°C, the average deposition rate wasincreased from26.7to45.3nm/min, respectively. In the corrosion process of the Ni-P film in1mol/L HCl, the dissolving rate decreased with contact time to a stable level of0.12nm/min.The wearing rate of the Ni-P film in Al2O3polishing powder was much larger than thedissolving rate in1mol/L HCl and decreased slightly with time. The ESPS technique is aneffective tool for in-situ monitoring of the mass changes in electroless plating on quartzmaterial.2) Response of quartz crystal microbalance with inhomogeneous film and monitor theadsorption behavior on the ice filmDuring the experiment stage of preparation an ice film on the surface of the QCM toinvestigate the adsorption behavior on the ice film, the splitting of the resonant peak of QCMwas observed if heavy and inhomogeneous film was prepared. We used a peak height weighted average method to get the information about the mass change on the surface underthe situation of peak split. We also studied the factors which affected the sublimation of icefilm at low temperatures. After the optimization of the conditions, homogeneous, rigid icefilm was prepared on the surface of the QCM and the resonance peak splitting was avoided.The sublimation rate of ice film was measured. The changes of mass and viscosity on the icefilm during the interaction with ethanol, HCl and NH3were investigated by QCM. Theinfluence of thickness of the ice film and the concentration of the gases on adsorption wasdiscussed. Ice film was melted after ethanol adsorption. The frequency change was duemainly to phase change of ice. In the HCl adsorption system, the frequency change came fromsurface adsorption and change in film viscosity. In the NH3adsorption system, the ice filmremained rigid, and the frequency change came from surface adsorption. We could distinguishand correct the frequency changes from ice film sublimation and non-mass effect using theimpedance analysis method. The result is helpful to expand the application of the QCM in lowtemperature causes.3) Influence of ultrasonic wave on the response of a quartz crystal microbalance inimpedance analysis methodThe effect of ultrasonic wave on the response of a quartz crystal microbalance (QCM)was investigated by an impedance analysis method. In the presence of ultrasonic wave, thesignal-to-noise of QCM in a liquid phase is reduced as burrs are added on itsimpedance-frequency spectrum. This kind of effect is ascribed to the fact that the reflectioncondition for the longitudinal wave from QCM is disturbed by ultrasonic wave. The burrnoise on the resonant peak of QCM disappears when the longitudinal wave effect iseliminated. The changes in the resonant frequency and motional resistance of QCM weremeasured under different viscosity and density of liquid phase and the surface mass loading. Itis shown that the thickness-shear model of QCM is not influenced by ultrasonic wave effect.The removal of hydrophobic film by non-ionic surfactant were monitored by QCM. Theremoval is greatly speeded under ultrasonic conditions. The result showed that QCM can beused under ultrasonic environment for reliable sensing detection.