ABSTRACTAlumina particles were treated under various conditions with different
diphenylphosphinate compounds: diphenylphosphinic acid, ethyl
diphenylphosphinate, and trimethylsilyl diphenylphosphinate. The balance
between surface complexation (namely grafting) and surface phase
transformation (formation of bulk aluminum phosphinate phase) was
investigated by IR and solid-state 31P MAS NMR spectroscopy,
using the model crystalline phase
Al(O2PPh2)3 synthesized in a parallel
work as a reference. Satisfactory grafting was obtained either by using
diphenylphosphinic acid in aqueous medium at pH about 6, or by using ethyl
diphenylphosphinate in organic medium as coupling agents.
Based on good processing property of two-dimentional ultrasonic vibration assisted grinding (TUVAG), phase transformation in the grinding surface of nanozirconia toughened alumina ceramics (ZTA ceramics) is studied by XRD analysis. Experimental results show different processing method and grinding depth may lead to surface phase transformation of ZTA ceramics. Under the same grinding parameters, phase transformation ratio of grinding surface under TUVAG is higher than that under diamond grinding (DG), and its phase transformation ratio increases with the increasing of grinding depth. Phase transformation ratio can effectively inhibit generation and expansion of microcracks of grinding surface.
The epitaxial growth of Ag on Si(111)-(7 x 7) surface and its (√3x√3)-R30 surface phase transformation