Papers by Keyword: Phytic Acid

Abstract: This study through a lot of theoretical analysis and experimental exploration, come to add phytic acid and chromium alum in the traditional zinc phosphating solution for phosphating solution film-forming speed and improve the film density has a distinct effect, and further by orthogonal experiments and the final assessment of preferred a group of environmental, low-temperature, and no sediment of new phosphating process. The composition of the phosphating solution is as follow: zinc oxide 0.5g/L; phosphating acid 5.0mL/L; tartaric acid 0.75g/L; sodium molybdate 0.6g/L; Ma Jif salt 2.0g/L; NaF 0.25g/L; phytic acid 0.4mL/L; chromium alum 1.0g/L; free acidity 2-4 points; total acidity 15-18 points. The experimental results show that: the new phosphating process of this study reduces the handling costs, the stability bath performance, little changes in acidity, in the case of do not need to adjust the surface at room temperature, to forming a completed, dense, strong corrosion-resistant color phosphate crystal film on metal surface within 5 minutes, the copper sulfate bit time is 2.5mins, with good adhesion to 0, the impact resistance is 50kg/cm, it can be used in conjunction with a variety of coating processes.

Abstract: This study investigated the flotation in sodium dodecyl benzene sulfonate system, the effects of phytic acid on talc flotation mechanism, then proposed a new flowsheet to handle this kind talc ore, namely “one roughing-three cleaning-one scavenging’’. The closed-circle flotation test in laboratory can obtain a concentrate with the SiO2 and CaO grade of the concentrate is 61.87% and 0.60%, the SiO2 recovery is 72.59%, removal rate of tremolitei is 95.85%. This paper improved the economic value of the talc containing asbestos, laid the foundation of industrial applications.

Abstract: Passivator components of phytic acid, hydrogen peroxide, boric acid and polyethylene glycol was optimized by orthogonal experiment. Corrosion resistance of passivation film of brass-strip was invertigated by salt spraying, weight loss and electrochemical test. The results show that the optimization passivator consists of phytic acid (50% mass fraction) 8ml/L, hydrogen peroxide (mass fraction 30%) 30ml/L, boric acid 5g/L, polyethylene glycol 15ml/L and additive 4g/L. Corrosion current density and corrosion rate of the brass-strip specimens coated by rich-phytic acid passivator are similar to that treated by traditional sodium dichromate passivator, the characteristic of anti-tarnish slightly better than that coated by sodium dichromate passivator. The feature of rich-phytic acid passivator is environmental protection.

Abstract: Phytic acid coatings were formed on 6063-Al alloy during immersion in phytic acid solution with various pH and phytic acid concentration for different time. The corrosion resistance of the coated samples was investigated using Tafel polarization technique. The results show that the effect of technological parameters on corrosion resistance of phytic acid coatings is great. With the increase of pH, the corrosion resistance of the coated sample is firstly increased and latterly decreased; it is optimum when pH was 3.0. The corrosion resistance of phytic acid coatings is increased largely with phytic acid concentration and immersion time. The anodic and cathodic corrosion processes of the coated 6063-Al alloy are inhibited markedly, and the corrosion current density is decreased for more than two orders of magnitude.

Abstract: Phytic acid coatings were formed on AZ91D-Mg alloy during immersion in 5.0 g/L phytic acid solution for different time. The corrosion resistance of the bare and coated samples was investigated using Tafel polarization and Electrochemical Impedance Spectroscopy (EIS) methods, and the corresponding electrochemical corrosion parameters were analyzed. The results show that the anodic and cathodic corrosion processes of AZ91D-Mg alloy are conspicuously inhibited with phytic acid coatings; the overall corrosion resistance index of AZ91D-Mg alloy is increased with immersion time; and the corrosion protection efficiency of phytic acid coatings is up to 97.8%.

Abstract: The surface of brass strip is easily oxidized to cause discoloration when exposed in the air. If it contacts with the electrolyte, there will be an electrochemical reaction in the surface that lead to increasing dezincification corrosion. To improve the anti-tarnish ability, the best method is to form a protective membrane in the strip surface. Phytic acid is easily formed a stable chelate complex compound with metal ions, so that forming a dense layer to protect brass strip. It is necessary to develop a new type surface passivator which rich in phytic acid and aquae hydrogenii dioxide but without Cr which pollutes the environment. The study results show that: This passivator enable the anti-tarnish capacity significantly, and do much better results and without so much pollution than now often used dichromate passivator. The passivator solution is stable and can use longer.

Abstract: AZ91 magnesium alloy is selected as the matrix metal. SEM, EDS, Tafel and EIS were adopted and spot test was carried out to investigate the influence of pH value, phytic acid concentration, temperature,conversion time on corrosion resistance of conversion coatings. Result shows that process of phytic acid forming is the controlled metal corrosion process and the uneven surface pattern reflects the different chemical properties of two-phase current on magnesium alloy surface, which is implied by the conversion surface. It is proved by the test that pH value is committed the most to the corrosion resistance of the conversion coating, and the next is the phytic acid concentration. It is found that the corrosion resistance of the conversion coating is the best when pH value of the conversion solution is 4.5; The conversion coating has little influence on the cathode reaction dynamics, however, more importantly, it changes the dynamics of the alloy electrode anode solution reaction, therefore, the alloy’s anode current density decreases while the corrosion resistance of magnesium alloy is enhanced.

Abstract: In a solution containing 10g/L NaOH and 12g/L phytic acid, anodic coatings were obtained by micro arc oxidation (MAO) on AZ91HP magnesium alloy. The morphology, structure and composition of anodic coatings were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX). The corrosion resistance of magnesium alloy before and after MAO treatment was evaluated by immersion test and potentiodynamic polarization testing in 3.5wt. % NaCl solution. The coatings were evenly formed on the substrate and mainly composed of MgO. EDX analyses showed that phytic acid took part in the coating formation. Compared with the substrate, the corrosion resistance of magnesium alloy after MAO treatment was improved considerably.

Abstract: With the aim of evaluating corrosion inhibition for various inhibitors, a new qualitative method for corrosion inhibition effect test for magnesium and magnesium alloys was developed. The change of polarization current density of AZ61 magnesium alloy in electrochemical polarization experiments in alkali aqueous solution with 5mmol/L sodium dodecylsulphate(SDS), phytic acid(PA), ethylenediamine tetraacetic acid(EDTA), p-nitro-benzene-azo-resorcinol(PNBAR), acidum tannicum(AT) or stearic acid(SA) were tested. The SEM-EDS techniques and deposition experiment method were used for further confirmation of the corrosion inhibition. The results showed that those organic compounds which could form the inhibitor-magnesium precipitation in aqueous solution could be used as corrosion inhibitors for magnesium alloys to inhibit the increase of polarization current density as well as the dissolution and oxidation of magnesium alloys effectively.

Abstract: An anticorrosion conversion coating on metal magnesium surface was prepared using immersion method in an aqueous solution containing mainly phytic acid. The coating after the preparation could be dry in the air without a rinse process using water in the final stage. Hence there is no discharge of waste water and waste gas in the whole process. Influence of several factors on the anticorrosion performance of coating was tested. And optimal parameters in the coating formation process were obtained from orthogonal test. The results indicated that the coating had better corrosion resistance, when the solution contained 3% phytic acid, and the immersion time is 7 minutes and the PH value was 3.5. The surface conversion coating was characterized by SEM and EDS. The conversion coating is better than the traditional chromate passive film by testing corrosion speed of coatings using hydrogen evolution method. The technology of the environment-friendly conversion coating containing phytic acid has the potential to be a new anti-corrosion technology for magnesium surface.