ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Amorphous Zn–Ca phosphates and crystalline Zn3(PO4)2·4H2O conversion layers on cathode substrates were prepared by electrolysis of mixtures of acidic solutions saturated with metal phosphates. The solutions contained tricalcium phosphate (Ca3(PO4)2) and/or zinc phosphate dihydrate (Zn3(PO4)2·2H2O). The depositions was carried out with constant or pulsating cathode current densities in the range 20–70 mA cm-2 at 20–70 °C. The deposition of the uniform crystalline Zn3(PO4)2·4H2O was performed at a pulsating cathode current density of 70 mA cm-2 at 70 °C for periods up to 10 min. Amorphous deposits of Zn–Ca phosphates containing 20 wt% H2O with variable Zn-to-Ca ratios were deposited at a constant cathodic current of 30 mA cm-2 at 20 °C for 3 min. Surface areas of the amorphous deposits were of the order of 28 m2 g-1. X-ray diffraction, differential thermal analysis and thermogravimetry were used to investigate phase formation and transitions at increasing temperatures. The amorphous Zn–Ca phosphate deposit was after calcination at 900 °C transformed to crystalline phosphates containing the β-Ca3(PO4)2 or Ca3-xZnx(PO4)2 and α-CaZn2(PO4) phases. © 1998 Kluwer Academic Publishers
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1004379319348
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