Complete corrosion inhibition of lamellar zinc pigment in aqueous alkaline media

Lamellar zinc pigment reacts in aqueous alkaline media (e.g., water-borne paints) with the evolution of hydrogen. This corrosion reaction can be inhibited by 2-nitrophenol (2-NP), 2,4-dinitrophenol (2,4-DNP), 2-hydroxy-3,5-dinitro-benzoic acid (HDNBA) and 2-hydroxy-3-nitro-benzoic acid (2-H-3-NBA) which all have a nitro-group ortho to a hydroxy-group; this structural part of the inhibitors can be considered as a potential chelating group which may explain the corrosion inhibiting effect. As a rule, with triethylamine (TEA) as neutralizing agent corrosion inhibition is slightly better when compared to dimethylethanolamine (DMEA). With TEA there is complete corrosion inhibition with addition of 2,4-DNP at pH 8 and 10; with 2-H-3-NBA there is complete inhibition at pH 10.     

家电产品常用板材的选用

本文首先介绍国内和日本、德国、俄罗斯等国冷轧薄钢板及镀锌薄钢板的牌号、标记识别及生产地及与我国家标准薄钢板牌号的相互之间的关系，并比较具体地介绍冷轧板的实效性、镀锌薄钢板的锌层特性等诸多方面的状况。从而帮助我们在设计、制造家电产品中，比较正确地选择合适的板材。     

THE REACTIVITY AND DURABILITY OF ZINC FERRITE HIGH TEMPERATURE DESULFURIZATION SORBENTS

Cylindrical pellets of zinc ferrite high temperature desulfurization sorbent have been prepared using a number of formulation recipes and induration conditions. Physical and structural properties of the resultant sorbents were measured, and reactivity and durability screening tests were carried out using a single pellet electrobalance reactor. The formulation variables studied were ZnO to Fe₂O₃ ratio, Fe₂O₃ source, and the addition of inorganic (bentonite) and organic (methocel) binders to the sorbents. Pellet induration conditions ranged from 0.25 hours at 815^°C to 4.0 hours at 1038°C. Stronger pellets having greater attrition resistance resulted when 5% bentonite was added to the formulation recipe and when the pellets were indurated at high temperature for extended times. In contrast, bentonite content was not a significant factor in determining sorbent reactivity and durability, both of which were improved by mild induration conditions. Sorbent regeneration temperature was found to be an important factor in improving reaction durability, as was the addition of 0.5% methocel to the formulation recipe. Pellets containing catalyst-grade Fe₂O₃ were more reactive than those containing pigment-grade Fe₂O₃. This effect, however, was less important than the effect of induration conditions.     

Corrosion failure of Zn–Al detonator housing

Some batches of detonator housings made up of Chromium plated Zn–Al alloy were found in an extensively cracked condition after few months of storage at room temperature. An analysis of the failure showed that the cracks were due to intergranular corrosion facilitated by segregation of lead at the grain boundaries. Improper chromium plating further aggravated the corrosion problem. This failure case emphasises the need for strict control of chemical composition for components made from Zn–Al alloy and the process of Cr plating of the components.     

A SVET investigation on the modification of zinc dust reactivity

Weldable primers are thin zinc-rich organic coatings that are weldable due to the electrical conductivity provided by the zinc dust. They are used in the automotive industry to provide corrosion protection in regions of difficult access. The zinc particles are highly susceptible to corrosion attack and, due to the small thickness, the protection conferred by these systems is limited.     

Optimisation of metallic pigments in coatings by an electrochemical technique and an investigation of manganese powder as pigment for metal rich primers

Zinc dust and manganese powder as pigments were incorporated in epoxy-polyamide and butyl titanate medium, with different pigment volume concentration (PVC) ranging from 20 to 74. These protective coatings were coated on sand blasted mild steel substrates and immersed in 3 wt.% sodium chloride solution and the corrosion current was measured by the Tafel extrapolation method. From the corrosion current produced by these primers, the optimum level of the pigments in these binders was identified. Thus the protective performance of optimised primers was evaluated on a sand blasted mild steel surface by the Tafel polarisation method in 3 wt.% sodium chloride solution, over different periods of time. The results were found to be comparable with the salt spray test and galvanic current measurements. The manganese powder used for this investigation showed that it could be used as an alternative to zinc powder for metal rich primers.     

Ethoxylated fatty alcohols as corrosion inhibitors for dissolution of zinc in hydrochloric acid

The effect of some ethoxylated fatty alcohols, with different numbers of ethylene oxide units, on the corrosion of zinc in 0.5 M HCl has been studied using weight loss and polarization measurements. The inhibition efficiency was found to increase with increasing concentration, number of ethylene oxide units per molecule and with decreasing the temperature. Inhibition was explained on the basis of adsorption of ethoxylated fatty alcohols molecules on the metal surface through their ethoxy groups. The degree of surface coverage varied linearly with logarithm of inhibitor concentration fitting Temkin isotherm. The thermodynamic parameters were calculated for the tested system from the data obtained at different temperatures.