Irena Szczygieł

Self-healing coatings in anti-corrosion applications

Nonmetallic (based on polymers or oxides) and metallic protective coatings are used to protect metal products against the harmful action of the corrosion environment. In recent years, self-healing coatings have been the subject of increasing interest. The ability of such coatings to self-repair local damage caused by external factors is a major factor contributing to their attractiveness. Polymer layers, silica-organic layers, conversion layers, metallic layers and ceramic layers, to mention but a few, are used as self-healing coatings. This paper presents the main kinds of self-healing coatings and explains their self-healing mechanisms.

Electroless deposition of Ni-P-nano-ZrO2 composite coatings in the presence of various types of surfactants.

Ni-P-nano-ZrO(2) coatings were produced using the electroless deposition technique. To prevent agglomeration of zirconia nanoparticles in the plating bath, various surfactant additives (anionic, cationic, and nonionic) were used. The most stable bath was obtained with the addition of dodecyltrimethylammonium bromide (DTAB). The impact of this surfactant on the deposition rate, coating composition, and topography, as well as ζ potential of particles, was examined. Surface morphology and composition of the Ni-P-nano-ZrO(2) composite coatings was analyzed by various techniques including scanning electron microscopy (SEM) equipped with in situ energy-dispersive X-ray (EDX) spectroscopy. Coatings with a clearly greater amount of zirconia (21.88-22.10 wt.%) were obtained from baths containing DTAB in concentrations equal to or above its critical micelle concentration (cmc). For these surfactant concentrations, the reduction of Ni and P content was observed.

Synthesis and characterization of manganese–zinc ferrite obtained by thermal decomposition from organic precursors

Mn–Zn ferrites were obtained by the sol–gel autocombustion methods. The effect of the precursor used in the sol–gel autocombustion synthesis on the ferrite’s microstructure was examined. The as-obtained powders were characterized by XRD, FTIR, SEM, and TG/DTA. All ferrite powders obtained from different organic precursors, after gel autocombustion, were pure spinel phase, without secondary phases. The average crystallite size, estimated from Scherrer equation, was the smallest for ferrite obtained from a mixture of fuels/precursors (citric acid and EDTA). This ferrite powder has sponge-like microstructure with large pores, but it is less agglomerated than the material obtained from glycine as the fuel.

Phase diagram for a portion of the system Ce2O3Na2OP2O5 rich in P2O5

Abstract The phase diagram for a portion of the ternary system Ce 2 O 3 Na 2 OP 2 O 5 rich in P 2 O 5 has been worked out. The durability of two cerium phosphates, CeP 5 O 14 and CeP 3 O 9 , was investigated and the melting point of CeP 5 O 14 determined (1064°C congruently). Phase diagrams of the two binary systems CeP 3 O 9 CeP 5 O 14 and NaCe(PO 3 ) 4 CeP 5 O 14 are presented.

Phase equilibria in the system CePO4Na3PO4

Abstract The phase diagram of the system CePO4Na3PO4 has been determined by differential thermal, X-ray, and microscopic methods. The system contains only one intermediate compound, Na3Ce(PO4)2, which melts incongruently at 1550°C. This compound is stable down to room temperature and exhibits a polymorphic transition at 1060°C. The low-temperature modification has an orthorhombic (lattice type P) unit cell with parameters a = 14.074(1), b = 16.039(1), and c = 18.607(1) A ; V = 4200.21 A 3 .

The system CePO4–KPO3–Ce(PO3)3

Abstract In the ternary system Ce 2 O 3 –K 2 O–P 2 O 5 the partial system CePO 4 –KPO 3 –Ce(PO 3 ) 3 has been examined by differential thermal analysis, powder X-ray diffraction and infrared spectroscopy. Its phase diagram has been determined.

Structural, Raman, FT-IR and optical properties of Rb3Y2(PO4)3 and Rb3La(PO4)2 doped with Eu3+ ions

Rb3Y2(PO4)3 and Rb3La(PO4)2, undoped and doped with Eu3+ ions, were synthesised either by the Pechini method or solid state reaction. They were characterised by thermoanalytical methods, X-ray diffraction, IR and Raman spectroscopy as well as optical techniques. It was stated that Pechini and solid state reaction methods give the compounds with the same structure. The structural data result in the P21/m space group with Z = 2 and a = 9.78 A, b = 5.76 A and c = 7.77 A cell parameters for Rb3La(PO4)2 and cubic symmetry I21/3 with a = 16.87 A and Z = 16 for Rb3Yb2(PO4)3. In Rb3La(PO4)2 the reversible β/α phase transition is observed in the 960–1070 °C temperature range. The lifetime of the 5D0 excited state measured at 77 K is about 4 and 2 ms for Rb3La(PO4)2 and Rb3Y2(PO4)3, respectively.

Phase equilibria in the system CePO4-Na3PO4-Na4P2O7

Abstract The ternary system CePO 4 -Na 3 PO 4 -Na 4 P 2 O 7 has been investigated by differential thermal analysis, powder X-ray diffraction and microscopy in reflected light and its phase diagram has been determined. The system contains only one double phosphate which is formed at 1:1 molar ratio of CePO 4 :Na 3 PO 4 , i.e. Na 3 Ce(PO 4 ) 2 .

XPS and FT-IR Characterization of Selected Synthetic Corrosion Products of Zinc Expected in Neutral Environment Containing Chloride Ions

ZnO, Zn(OH)2, Zn5(OH)8Cl2·H2O, ZnCO3, and Zn5(CO3)2(OH)6 synthetic powders were prepared by chemical or solid-state method. Their crystalline phase structure, thermal behavior, and morphology were examined. Characteristic infrared absorbance bands were estimated by means of FT-IR ATR spectroscopy. X-ray photoelectron spectroscopy (XPS) allowed to calculate the modified Auger parameters (α ′) thereof to 2010.2, 2009.3, 2009.4, 2009.7, and 2009.8 eV, respectively for ZnO, Zn(OH)2, Zn5(OH)8Cl2·H2O, ZnCO3, and Zn5(CO3)2(OH)6. Finally, comparison of surface composition may be crucial to evaluation of the unknown experimental spectra of corrosion products formed on the surface of zinc alloy coatings exposed in NaCl solution.

Model studies on the separation of Ca2+ and Nd3+ ions using ethylenediaminetetraacetic acid

Studies on the separation of calcium and neodymium ions by using ethylenediaminetetraacetic acid (H4EDTA) as a complexing agent were performed. This research was undertaken due to the possibility of H4EDTA applying to isolate rare earth elements from the solution after acidic leaching of phosphogypsum, and because of the similarity of coordination properties of calcium and lanthanides ions. The experiment was carried out in model systems containing Ca2+ and Nd3+ ions in hydrochloric or sulphuric acid. The content of calcium and neodymium metals, phase composition and thermal behaviour of the obtained products were determined by ICP-OES, FTIR, XRD and TG/DTA techniques. During the separation process, the precipitates of a light pink colour were obtained. The obtained results show that the neodymium ethylenediaminetetraacetate has been successfully formed and that the isolation of neodymium ions was more efficient in chloride medium. The precipitate included 72.2 and 3.9% of the starting amount of neodymium and calcium used in the experiment, respectively. However, in sulphates medium, these amounts were equal to 73.8 and 53.5%, respectively. Moreover, the obtained powder was polluted with sulphates. The addition of the EDTA in an excess (15%) contributed only to an increase in calcium content in the complex.