Electrodeposition of nanostructured columnar cobalt for self-lubricant coatings

Author(s): Zhao, F.; Franz, S.; Vicenzo, A.; Cavallotti, P. L.; Sansotera, M.; Navarrini, W.

Source: ELECTROCHIMICA ACTA Volume: 56 Issue: 26 Special Issue: SI Pages: 9644-9651

DOI: 10.1016/j.electacta.2011.06.033 Published: NOV 1 2011

ABSTRACT:

The preparation of cobalt-perfluoropolyether (PFPE) composite coating with dry lubrication capability is addressed. An original process scheme is proposed involving the electrodeposition of a nanostructured columnar cobalt layer, a grain boundary etching post-deposition treatment of the layer and its further processing by vacuum impregnation with PFPE. The influence of the operating parameters on deposition kinetics and crystal structure of the cobalt layer was investigated in detail, with the objective of identifying the optimum deposition conditions for the growth of a nanocolumnar cobalt film. In particular, the main operating conditions, namely deposition temperature and current density, were analyzed by studying their effect on deposits microstructure and texture. Control of the growth stability of the nanocolumnar structure was achieved in the presence of a suitable concentration of a surfactant. The subsequent steps of grain boundary etching and impregnation with PFPE were successfully implemented completing the planned process scheme. Friction force measurements provided evidence validating the functionality of the Co-PFPE nanocomposite.

http://www.sciencedirect.com/science/article/pii/S0013468611009194

Peroxidic perfluoropolyether for the covalent binding of perfluoropolyether chains on carbon black surface.

Author(s): SANSOTERA M., NAVARRINI W., GOLA M., BIANCHI C. L., WORMALD P., FAMULARI A., AVATANEO M.

Source: Journal of Fluorine Chemistry.

Volume: 132 (12) Pages: 1254-1261.

DOI: 10.1016/j.jfluchem.2011.07.018. Published: Dec. (2011).

ABSTRACT

Peroxidic perfluoropolyethers (PFPEs) are suitable tools for the covalent linkage of fluorinated groups on substrates containing aromatic moieties. Thus the thermal decomposition process of such fluorinated peroxides allowed the covalent linkage of PFPE radicals to the polycyclic aromatic structure of a graphitic carbon black. Contact angle measurements on molded pellets made with modified carbon black powders revealed a gradual enhancement of the hydrophobicity, which follows the increase of the fluorine content on the surface according to XPS experiments. BET analyses also revealed variations of the surface area of carbonaceous samples. Products and by-products were also evaluated by mass balances of decomposed portions of PFPE residues, respectively, PFPE chains bonded on carbon black and PFPE fluids obtained by homocoupling side-reactions. Modified carbonaceous materials were analyzed by solid state 19F-MAS NMR and the results are in agreement with the proposed radical mechanism.

http://www.sciencedirect.com/science/article/pii/S0022113911002831

alpha,omega-dialkoxyfluoropolyethers: a promising class of hydrofluoroether (HFE).

Author(s): WU M., NAVARRINI W., AVATANEO M., VENTURINI F., SANSOTERA M., GOLA M.

Source: Chimica Oggi – Chemistry Today.

Volume: 29 (3) Pages: 67-71. Published: Jun. (2011).

ABSTRACT:

The alpha,omega-dialkoxyfluoropolyethers (DA-FPEs) characterized by structure RHO(CF2CF2O)n(CF2O)mRH have been recently developed as a new class of environmental friendly hydrofluoropolyethers (HFPEs) suitable as solvents, refrigerants and heat transfer. The synthetic methodologies for the preparation of this new class of fluid have been reviewed and physical properties of selected alpha,omega-dimethoxyfluoropolyethers have been evaluated and compared with analogous hydro- fluoropolyethers (H-FPEs) having -OCF2H as end-groups. Atmospheric implications and global warming potentials (GWP) of selected alpha,omega-dimethoxyfluoropolyethers have been also considered.

http://www.teknoscienze.com/Articles/Chimica-Oggi-Chemistry-Today–alpha-omega-dialkoxyfluoropolyethers-a-promising-class-of.aspx#.UozCCCcUlZM

Henri Moissan 1906 Nobel Prize on Chemistry

Author(s): Navarrini, Walter

Source: CHIMICA OGGI-CHEMISTRY TODAY

Volume: 29 Issue: 3 Pages: 4-5 Published: MAY-JUN 2011

ABSTRACT:

Professor H. Moissan madeoutstanding contributions to thedevelopment of applied chemistry inthe late XIX and early XX century. For thefirst time he obtained fluorine in freestate, studied a number of fluorinecompounds, designed an electricarc furnace and set the foundationof high-temperature chemistry.He synthesized many high-meltingcompounds and isolated boron andother elements by reducing their oxides, finallyhe theorised and attempted the preparation of artificial diamond(1). He was awarded with the Nobel Prize (1906) in recognition to theisolation of fluorine and for his studies on high-temperature chemistry.He died suddenly in Paris in February 1907, shortly after his return fromreceiving the Nobel Prize in Stockholm.

http://www.teknoscienze.com/Articles/Chimica-Oggi-Chemistry-Today-Henri-Moissan-1906-Nobel-Prize-on-Chemistry.aspx

Anti-Fingerprints Fluorinated Coating for Anodized Titanium Avoiding Color Alteration.

Author(s): NAVARRINI W.; BRIVIO T.; CAPOBIANCO D.; DIAMANTI M. V.; PEDEFERRI M.; MAGAGNIN L.; RESNATI G.

Source: JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH.

Volume: 8 Issue: 2 Pages: 153-16.

DOI: 10.1007/s11998-010-9293-y Published: Mar. (2011).

ABSTRACT:

In this study amorphous fluorinated coatings applied to anodized titanium surface have been investigated. A copolymer between tetrafluoroethylene and perfluoro-4-trifluoromethoxy-1,3-dioxole (AD60) and two perfluoropolyether containing ammonium phosphate (F10) or triethoxysilane (S10) functionalities have been tested. To estimate the color alteration of the anodized titanium surfaces due to the application of the coatings, spectrophotometric analyses have been made. Water and n-dodecane contact angles as well as apparent surface energy have been evaluated. Ellipsometry and atomic force microscopy data have been used to measure the thickness of the fluorinated coatings. A tailored mechanical preliminary test has also been explored to evaluate the adhesion of the coatings on the anodized titanium surface. The resistance to surface soiling with castor oil was also preliminarily investigated. The fluorinated coating tested on anodized titanium showed a low apparent surface energy and high chromatic aspect conservation, this is particularly evident for the titanium anodized coated with triethoxysilane functionalities fluoropolymers S10. http://link.springer.com/article/10.1007%2Fs11998-010-9293-y