Papers by Keyword: Cerium Nitrate

Abstract: In the present work we analyzed the anti-corrosive properties, on AA6061, of sol-gel silane-zeolite hybrid coatings doped with cerium nitrate ions as inhibitor. Three different types of composite coatings were prepared by using cerium doped zeolite and/or silane matrix. For each type, four formulations, varying the zeolite amount (in the range 60-90% wt), were tested. All composite coating evidenced a high homogeneity and good adhesion performances. Cerium addiction in the coating formulation did not compromise the hydrophobic properties of the coating. Furthermore the addition of the cerium ions improved the anti-corrosion properties of the composite films inducing a significant stability of the electrochemical behavior.

Abstract: Based on the inorganic and organic composite pretreatment technology, a new chromium-free pretreatment solution consisting of Ce (NO₃)₃, N-β (aminoethyl)-γ-aminopropyl trimethoxysilane (KH792) and vinyltrimethoxysilane (KH171) was studied and used to treat galvanized sheet. Corrosion resistance of composite silane films on galvanized sheet surfaces was studied using CuSO₄ pitting corrosion test and neutral salt spray test. Experimental results show that the corrosion resistance of composite silane film has improved significantly, compared to single silane film. The optimal condition of chromium-free pretreatment solution is that KH792/KH171 ratio is 4/1(v/v), Ce (NO₃)₃ content is 0.05%(w/w).

Abstract: Three rare earth salts: La(NO₃)₃, LaCl₃ and Ce(NO₃)₃ were used to study their broad spectrum inhibitory effect on micro-organisms to look for an effective additive for microbial inoculant. YMA solid media containing different concentrations of RE ³⁺ (200, 400, 600, 800, 1000 mg L^-1) were exposed to air and been smeared soil solution, respectively, for contamination study. Results indicating that for air microbes, the inhibitory effect on microbe number of the 3 rare earths was Ce(NO₃)3 > LaCl₃ > La(NO₃)₃, and for soil microbes, it was La(NO₃)3 > Ce(NO3)3 > LaCl3. On the whole, microbe diameters decreased as RE ³⁺ concentration increase, except that mass microbes occurred in high density. Actinomycetes were the most sensitive microbes to RE3+ stress, which could be inhibited at low RE ³⁺ concentrations (200 and 400 mg L^-1), followed by bacteria and mould.

Abstract: This present work investigated the corrosion behavior of AZ31 magnesium alloy substrates pre-treated with bis-[triethoxysilylpropyl] tetrasulfide silane modified with cerium nitrate. The corrosion behavior of the pre-treated substrates in 0.005M sodium chloride solutions was assessed by potentiodynamic polarization, open circuit potential and electrochemical impedance spectroscopy (EIS). The results showed that the silane pre-treatments improved the corrosion resistance of the AZ31 magnesium alloy substrates in the presence of chloride ions. Especially the addition of cerium nitrate played an important role in reducing the corrosion activity.

Abstract: Nickel coated gadolinium doped ceria (GDC) powder was synthesized by microwave radiation and combustion. For the synthesis, the precipitates of gadolinium cerium oxycarbonate hydrate (GdxCe2-xO(CO3)2·H2O) were formed by a microwave radiated reaction between cerium nitrate (Ce(NO3)3.6H2O) and gadolinium nitrate (Gd(NO3)3.6H2O) and urea (CO(NH2)2), then nickel coatings on the gadolinium cerium oxycarbonate hydrate were performed by further microwave reaction between nickel chloride and urea. The shape and size of the gadolinium cerium oxycarbonate hydrate particles were critically dependent on aging time during microwave radiation. The irregular particles were transformed to rod shape particles with well-crystallized with increasing aging time to 40 min at 70 - 80°C because of the gradual decomposition of urea during microwave radiation. Small nickel precursor particles were homogeneously coated on the gadolinium cerium oxycarbonate hydrate particles with rod shape with aid of microwave radiation at 80 °C for 40 min. As a result, the nickel coated GDC nanopowders were sucessfully produced by the microwave radiation synthesis and further microwave combusted at 450°C for 20 min.