Phosphate Pretreatment Research Articles

Effect of zinc phosphate pretreatment on micro-arc oxidation performance

Effect of zinc phosphate pretreatment on micro-arc oxidation performance

Environmentally friendly and facile Mg(OH)2 film for electroless nickel plating on magnesium alloy for enhanced galvanic corrosion inhibition

Electroless amorphous nickel (Ni)–phosphorus (P) (NiP) alloy coatings were successfully achieved on magnesium alloys using an environmentally friendly and facile Mg(OH)2 conversion film, followed by AgNO3 activation. The success of the coating was confirmed through scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction characterizations. Electrochemical tests showed that the charge transfer resistance of the newly developed electroless NiP plating coating, which had a horizontally stacked Mg(OH)2 nanosheet primer (Mg(OH)2/pH 14/ENP), was significantly higher than that with a vertically grown Mg(OH)2 nanosheet underlayer (Mg(OH)2/pH 10/ENP) or that with a phosphate pretreatment (ENP). The measured corrosion current density of the Mg(OH)2/pH 14/ENP coating was 1.08 μA cm−2, one magnitude smaller than that of the ENP coating. Notably, the ENP coating exhibited severe galvanic corrosion, peeling off after only 24 h of the neutral salt spray (NSS) test. In contrast, the Mg(OH)2/pH 14/ENP surface showed no visible corrosion cavities or signs of galvanic corrosion even after 120 h of the NSS test or 21 d of exposure to a NaCl solution. These results indicate that the as-prepared coating possesses a strong inhibition capability against galvanic corrosion between the Ni layer and the magnesium alloy, providing long-lasting corrosion protection.

Effect of Zirconium Conversion Coating on Corrosion Resistance of Small-Defected Auto Steel Sheets

For the sake of environmental protection and energy conservation, traditional phosphate pretreatments have been gradually prohibited worldwide during automobile productions. As a promising substitute, the green and environment-friendly zirconate pretreatment technology is developing rapidly. However, because the thickness of zirconium conversion coatings is commonly ranged in nanoscale, its covering capability for small defects is inferior to that of phosphate film, which may have a detrimental impact on the service performance of automotive steel sheets. In this study, comparing the surface characteristics of cold rolled auto steel sheets before and after zirconate treatment, the effects of zirconium conversion coating on the surface defect transmission and the corrosion resistance of the sheet were investigated. The results showed that although the defects were detected and recognized after the treatment, the coating was able to grow normally at the surface of small defects and effectively improve the corrosion resistance of the defects. The surface corrosion resistance for some types of defects was basically equivalent to that of the intact surfaces.

Integrated biorefinery of Mucor circinelloides biomass and sugarcane bagasse for application of high-value biopolymers

The replacement of expensive components in microbial growth media with pretreated lignocellulosic waste component to increase the product spectrum and add value to the bioproducts has been encouraged to achieve sustainable and feasible utilization of waste biomass as per the biorefinery approach. This study demonstrates an integrated biorefinery approach towards utilization of sugarcane bagasse and biomass of Mucor circinelloides ZSKP. A maximum reducing sugar recovery of 80.67 g/l was achieved after combining pretreatment with saccharification. A low temperature, glycerol, and ammonium phosphate pretreatment method was established, where glycerol pretreatment conditions were reduced from 250 to 150 °C and from 120 to 45 min. The ammonium phosphate-containing hydrolysate yielded 12.89 g/l of fungal biomass after fermentation to add to 20.8 g lignin from the delignification step. The biomass production was further improved to 17.69 g/l after supplementation with corn steep solids and mineral salts. The fermentation process also yielded 2.36 g/l chitosan and 4.9 g/l of lipids after extraction from the oleaginous fungus. The lignin infused glycerol plasticized chitosan biocomposite plastic had a 100% improvement in thermogravimetric properties with almost 50% more energy needed to increase the temperature of the material when compared to glycerol only plasticized biocomposite. The fungal chitosan showed antimicrobial properties and was effective as a preservative spray for fresh tomatoes and apples extending their shelf life to at least 14 and 18 days, respectively. This study therefore demonstrated that a novel two-step pretreatment process could be environmentally beneficial and yielded multiple products for biotechnological applications.

Effects of Pretreatment and Polarization Shielding on EK-PRB of Fe/Mn/C-LDH for Remediation of Arsenic Contaminated Soils

In this study, coupling electrokinetic (EK) with the permeable reactive barriers (PRB) of Fe/Mn/C-LDH composite was applied for the remediation of arsenic-contaminated soils. By using self-made Fe/Mn/C-LDH materials as PRB filler, the effects of pretreatment and polarization shielding on EK-PRB of Fe/Mn/C-LDH for remediation of arsenic contaminated soils were investigated. For the pretreatment, phosphoric acid, phosphoric acid and water washing, and phosphate were adopted to reduce the influence of iron in soil. The addition of phosphate could effectively reduce the soil leaching toxicity concentration. The removal rate of the soil pretreated with phosphoric acid or phosphoric acid and water washing was better than with phosphate pretreatment. For the polarization shielding, circulating electrolyte, electrolyte type, anion and cation membranes, and the exchange of cathode and anode were investigated. The electrolyte circulates from the cathode chamber to the anode chamber through the peristaltic pump to control the pH value of the electrolyte, and the highest arsenic toxicity removal rate in the soil reaches 97.36%. The variation of total arsenic residue in soil using anion and cation membranes is the most regular. The total arsenic residue gradually decreases from cathode to anode. Electrode exchange can neutralize H+ and OH- produced by electrolyte, reduce the accumulation of soil cathode area, shield the reduction of repair efficiency caused by resistance polarization, enhance current, and improve the removal rate of arsenic in soil.

Constructing stable surface structures enabling fast charging for Li-rich layered oxide cathodes

Li-rich Mn-based layered oxides (LLOs) exhibiting ultrahigh specific capacity larger than 250 mAh g−1 have become the most promising cathode candidate for high energy density lithium-ions batteries (LIBs). Fast charging capability and cycling stability are highly desirable for LIBs so as to satisfy specific application scenarios such as electric vehicles. However, stable cycling and fast charging properties are severely hindered by obstacles including irreversible oxygen release, structural degradation and poor reaction kinetics. In this work, an integrative and facile surface structures constructing strategy to achieve stable cycling and fast charging in LLOs was provided. Oxygen vacancies and double coating layers including lithium phosphate layer and spinel layer were constructed on the surface through ammonium dihydrogen phosphate (NH4H2PO4) pretreatment. The designed material with induced stable bi-phase coating layers delivers a high discharge specific capacity of 284.6 mAh g−1 at 0.1 C with an ultrahigh initial coulombic efficiency of 95.3% and excellent rate performance of 132.2 mAh g−1 at 10 C. Even after 100 cycles, it can display a remarkable capacity of 215.8 mAh g−1 under 1 C/1 C and 205.1 mAh g−1 under 3 C/1 C. The excellent fast charging performance and cycling stability can be attributed to accelerated Li+ transportation rate due to its surface ion conductive layer and surface spinel phase layer, as well as suppressed oxygen release, transition metals dissolution and electrolyte attack resulting from surface oxygen vacancies and dual protective layers.

Effect of Phosphate Pretreatments on Properties of Pyrolytic Products from Heavy-Metal-Contaminated Biomass

Vegetation has successfully been used for remediation of heavy metal contaminated soils (phytoremediation). The heavy-metal-rich biomass after phytoremediation can be processed by pyrolysis, achiev...

Corrosion Resistance and Cathodic Disbondment of Epoxy Coating Applied on Zinc Phosphate Conversion Coating Containing Different Amounts of Cobalt Ions

In this study, the influence of phosphate surface pretreatment containing a cobalt ion additive on the anti-corrosion features of epoxy coating was investigated. Phosphate conversion coating (PCC) specimens were prepared. Then the epoxy coating was electrostatically sprayed on the phosphated substrate. The surface morphology and the composition of a zinc phosphate conversion coating with a cobalt ion additive were studied by scanning electron microscopy and X-ray diffraction, respectively. Also, the corrosion protection properties of specimens were studied by the polarization potentiodynamic test in 3.5% NaCl solution. Protective performance of double-layer coatings was studied using electrochemical impedance spectroscopy during 30 days in the mentioned solution. In addition, the impact of phosphate chemical treatment on increasing the adhesion strength of the powder coating was studied using the pull-off adhesion test and cathodic disbodnment test in the same solution. As a result, it was found that the corrosion resistance of PCC containing a cobalt additive enhanced significantly and that the PCC containing 3 g/L Co is less porous than other coatings. Also, the protection properties, adhesion strength, and cathodic disbondment resistance of the double-layer coatings with phosphate pretreatment containing 3 g/L Co increased significantly.

In Vitro Osteocompatibility and Enhanced Biocorrosion Resistance of Diammonium Hydrogen Phosphate-Pretreated/Poly(ether imide) Coatings on Magnesium for Orthopedic Application.

Magnesium, as a biodegradable metal, is a promising candidate for biomedical applications. To modify the degradation behavior of magnesium and improve its osteocompatibility, chemical conversion and spin coating methods were combined to develop a diammonium hydrogen phosphate-pretreated/poly(ether imide) (DAHP/PEI) co-coating system. The diammonium hydrogen phosphate pretreatment was employed to enhance the attachment between PEI coatings and the magnesium substrate; meanwhile, it could serve as another bioactive and anticorrosion layer when PEI coatings break down. Surface characterization, electrochemical tests, and short-term immersion tests in DMEM were performed to evaluate DAHP/PEI coatings. Electrochemical measurements showed that DAHP/PEI coatings significantly improved the corrosion resistance of pure magnesium. No obvious changes of the chemical compositions of DAHP/PEI coatings occurred after 72 h of immersion in DMEM. An in vitro cytocompatibility study confirmed that viability and LDH activity of human osteoblast-like cells on DAHP/PEI coatings showed higher values than those on the DAHP-pretreated layer and pure magnesium. The DAHP-pretreated layer could still enhance the ALP activity of MG-63 cells after the degradation of PEI in DAHP/PEI coatings. Besides that, the in vitro cellular response to the treated magnesium was investigated to gain knowledge on the differentiation and proliferation of human adipose-derived stem cells (hADSCs). Cell distribution and morphology were observed by fluorescence and SEM images, which demonstrated that DAHP/PEI coatings facilitated cell differentiation and proliferation. The high level of C-terminals of collagen type I production of hADSCs on DAHP/PEI coatings indicated the potential of the coating for promoting osteogenic differentiation. Positive results from long-term cytocompatibility and proliferation tests indicate that DAHP/PEI coatings can offer an excellent surface for hADSCs.

CORROSION PROTECTION OF CARBON STEEL USING ZIRCONIUM OXIDE/SILANE PRETREATMENT AND POWDER COATING

Surface pretreatment plays important role in improvement of corrosion resistance and adhesion of organic coatings. A new generation of metal pretreatments based on nanosize zirconium oxide or ogranosilane film has been investigated recently as an alternative method to phosphatation. In this paper, ZrO2/silane composite film on carbon steel was prepared and characterised by field emission scanning electron microscopy, energy dispersive X-ray spectrum and electrochemical measurements. The effect of ZrO2/silane surface treatment on the protection properties of powder coating was studied by salt spray test and adhesion measurement. The results obtained showed that ZrO2 was rapidly precipitated on the steel surface after first 1 minute immersion and ZrO2/silane film formed after 4 minutes immersion give best protective properties. Powder coating on carbon steel with ZrO2/silane pretreatement has equivalent protection performance like powder coating with phosphate pretreatment.

Effect of Strontium Pretreatment on Zinc Phosphate Coating Deposition on Magnesium Alloy

Abstract Application of nano zinc phosphate coating on magnesium alloy via strontium phosphate pretreatment being studied. Preliminary investigation has been carried out to observe the pretreated and unpretreated phosphate coating on magnesium alloys. The observations were made during the process, and the phosphate deposition on specimen surface were discussed. Based on the surface morphology observation, pretreated sample showed better coating compared to unpretreated sample. The findings were consistent with electrochemical impedance spectroscopy which indicated better corrosion protection characteristics of the pretreated sample compared with the unpretreated one. Further investigation needs to be undertaken to establish the optimum pretreatment parameters in order to develop a new phosphate coating composition.

Distributing sulfidized nanoscale zerovalent iron onto phosphorus-functionalized biochar for enhanced removal of antibiotic florfenicol

Aggregation of nZVI and sulfur-modified nZVI (S-nZVI) can lower its reactivity with contaminants in water. To overcome this limitation, we synthesized biochar-supported nZVI and S-nZVI using a phosphate pretreatment of the biochar (pBC) to uniformly distribute the nZVI and S-nZVI onto the biochar support. The participation of phosphorus groups in the synthesis, and the good distribution of S-nZVI on the pBC were confirmed by FTIR, SEM, XRD, and XPS. Pretreatment of the biochar led to smaller well-dispersed S-nZVI compared to S-nZVI supported on untreated biochar. This increased the surface area of the S-nZVI and the reaction rate with the antibiotic florfenicol (FF). The removal rate of FF by pBC-S-nZVI was 4.3 times higher than that by unsupported S-nZVI. Even though FF strongly adsorbed to the pBC support, FF was fully degraded based on the mass balance results. Surface area normalized reaction rate constants (kSA) for FF removal by S-nZVI, BC-S-nZVI, and pBC-S-nZVI were similar, suggesting that the enhanced reactivity is due to the greater dispersion of S-nZVI on the treated biochar. These results provide a simple pretreatment method for dispersing nZVI or S-nZVI onto biochar supports.

Effect of Ionic Liquid 1-Butyl-3-Methyl-Imidazolium Dihydrogen Phosphate Pretreatment on Pyrolysis of Lignin

In order to improve the yield of liquid fraction and phenolics content during lignin pyrolysis, an effective method of lignin pyrolysis through the pretreatment of lignin by an acidic ionic liquid 1-butyl-3- methyl-imidazolium dihydrogen phosphate ([Bmim]H2PO4) at low temperature is investigated in this study. It is found that [Bmim]H2PO4 pretreatment increases the total yield of liquid products of lignin pyrolysis compared to that of original lignin. The [Bmim]H2PO4 pretreatment temperature significantly impacts the behaviors of the lignin pyrolysis. In the temperature range of 50 to 150°C, the yield of the overall liquid product obtained by pyrolysis of the sample pretreated at 50°C is the highest. After pretreatment, the [Bmim]H2PO4 can be efficiently recovered, but the structure and stability of the [Bmim]H2PO4 have been changed. The FTIR analysis shows that the ionic liquid [Bmim]H2PO4 pretreatment can break hydrogen bonds, ether linkages and ester bonds in lignin.

Adsorption and desorption of Cu2 + on paddy soil aggregates pretreated with different levels of phosphate

Interactions between anions and cations are important for understanding the behaviors of chemical pollutants and their potential risks in the environment. Here we prepared soil aggregates of a yellow paddy soil from the Taihu Lake region, and investigated the effects of phosphate (P) pretreatment on adsorption-desorption of Cu2+ of soil aggregates, free iron oxyhydrates-removed soil aggregates, goethite, and kaolinite with batch adsorption method. The results showed that Cu2+ adsorption was reduced on the aggregates pretreated with low concentrations of P, and promoted with high concentrations of P, showing a V-shaped change. Compared with the untreated aggregates, the adsorption capacity of Cu2+ was reduced when P application rates were lower than 260, 220, 130 and 110mg/kg for coarse, clay, silt and fine sand fractions, respectively. On the contrary, the adsorption capacity of Cu2+ was higher on P-pretreated soil aggregates than on the control ones when P application rates were greater than those values. However, the desorption of Cu2+ was enhanced at low levels of P, but suppressed at high levels of P, displaying an inverted V-shaped change over P adsorption. The Cu2+ adsorption by the aggregate particles with and without P pretreatments was well described by the Freundlich equation. Similar results were obtained on P-pretreated goethite. However, such P effects on Cu2+ adsorption-desorption were not observed on kaolinite and free iron oxyhydrates-removed soil aggregates. The present results indicate that goethite is one of the main soil substances responsible for the P-induced promotion and inhibition of Cu2+ adsorption.

Stabilization of Pb(II) accumulated in biomass through phosphate-pretreated pyrolysis at low temperatures

The remediation of heavy metal-contaminated soil and water using plant biomass is considered to be a green technological approach, although the harmless disposal of biomass accumulated with heavy metals remains a challenge. A potential solution to this problem explored in this work involves combining phosphate pretreatment with pyrolysis. Pb(II) was accumulated in celery biomass with superior sorption capacity and also in ordinary wood biomass through biosorption. The Pb(II)-impregnated biomass was then pretreated with phosphoric acid or calcium dihydrogen phosphate (CaP) and pyrolyzed at 350 or 450°C. Pb(II) from biomass was in turn almost totally retained in chars, and the percentage of DTPA-extractable Pb(II) was reduced to less than 5% of total Pb(II) in chars through CaP pretreatment. Pb(II) stabilization was further confirmed through a sequential extraction test, which showed that more than 95% of Pb(II) was converted into stable species composed mainly of lead phosphates according to X-ray diffraction (XRD) and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analyses. Overall, phosphate-pretreated pyrolysis can stabilize both Pb(II) and degradable biomass, so as to control efficiently the hazards of heavy metal-contaminated biomass.

Effect of ionic liquid 1-butyl-3-methyl-imidazolium dihydrogen phosphate pretreatment on pyrolysis of Shengli lignite

The pyrolysis behaviors of Shengli lignite (SL) pretreated with ionic liquid 1-butyl-3-methyl-imidazolium dihydrogen phosphate ([Bmim]H2PO4) was studied in this paper. The effect of pretreatment temperature and the ratio of [Bmim]H2PO4 to SL on the pyrolysis behaviors of lignite were mainly investigated. Also the mechanism of the influence of [Bmim]H2PO4 pretreatment on the pyrolysis of lignite was investigated by FTIR analysis. It is found that [Bmim]H2PO4 pretreatment results in the drastical increase of the yield of tar, especially the yield of oil fraction. The yield of tars obtained from pyrolysis of SL treated in [Bmim]H2PO4 at 200°C with the ratio of [Bmim]H2PO4 to SL at 1 increases by 1.7 times compared to that of SL. [Bmim]H2PO4 pretreatment results in the increase of yield of oil fraction, especially the yield of arenes and phenolics. The FT-IR analysis shows that [Bmim]H2PO4 pretreatment results in the increase of the content of carbonyl group and ether bond in SL.

Friction reduction of pre-phosphating nanofilm on bearing steel by tricresyl phosphate pretreatment in boundary lubrication

The study shows that the boundary lubrication performance of bearing steel can be improved by pretreatment with tricresyl phosphate. By X-ray photoelectron spectroscopy and scanning electron microscopic analyses of pre-slid and slid-bearing steel specimens, some mechanisms likely related to such improvement in tribological performance are revealed. It is identified that: (i) production of nanophosphate film on steel surface reduces friction from 0.08 to 0.035 and enhances anti-wear ability; (ii) wear mode is mainly ploughing in nature; and (iii) tricresyl phosphate surface pretreatment prevents the oxidation of lubricant oil. Such findings give some insight to applying tricresyl phosphate pretreatment on modifying the tribological behaviors of the rolling bearing of aeroengine.

Study of role of phosphate coating properties on electrophoretic paint performance by EIS and simulated corrosion tests

The influence of phosphate bath chemistry on phosphate coating properties and, eventually, on corrosion resistance properties of electrophoretic (ED) painted steel samples was examined. Two types of zinc phosphate bath chemistry with different concentration of zinc and nickel ions, and different values of total acid, free acid, and accelerator content were studied. The phosphate bath with higher value of acid ratio (total acid/free acid), nickel ion concentration, and accelerator point produced the best phosphate coating on steel surface with globular microstructure, small crystal size, high P ratio, and uniform coverage. Phosphate coated and only alkali cleaned samples were cathodic ED painted. Their corrosion resistance properties were evaluated by salt spray test, cyclic corrosion test and electrochemical impedance spectroscopy. The relative increase in corrosion resistance of painted sample due to best phosphate coating was 1·4 to 1·8×. Paint adhesion of samples significantly deteriorated when painted without phosphate pretreatment.

Evaluation of a sulfursilane anticorrosive pretreatment on galvannealed steel compared to phosphate under a waterborne epoxy coating

Galvannealed coatings are produced by annealing zinc hot dip coated steel where iron and zinc undergo interdiffusion to form iron–zinc alloys. They offer some attractive features like better weldability, paintability, corrosion resistance, ductibility and formability, depending on the morphology, composition and structure of the coating phases. Silane films are a good choice to replace phosphate pretreatment, and in the case of bis-sulfursilane films, the sulfur chains also help to increase the hydrophobicity of the film and its protection against corrosion. Epoxy coatings are reasonably corrosion resistant and generally applied as primers or direct-to-metal (DTM) coatings in coating systems for different metallic substrates.Using the optimum conditions previously determined for obtaining a 3% bis-1,2-[triethoxysilylpropyl] tetrasulfide (BTESPT) solution in a water/ethanol solvent at pH 4 hydrolyzed in the presence of 50ppm Ce(IV) ions, the silane solution was applied on galvannealed steel samples by dip coating process with samples remaining immersed for 15min before being withdrawn and cured for 40min at 150̊C. The bare galvannealed samples were previously treated, first by sonication in acetone and then by a commercial alkaline degreasing solution. The phosphate samples were prepared in an industrial set using the tricationic bath containing Mn, Zn and Fe phosphates.The waterborne epoxy coating was applied with a brush to reach a 60±6μm dry film thickness layer. The evaluation was performed by electrochemical technique: EIS, electrochemical impedance spectroscopy, and also by accelerated tests in a salt spray cabinet (SSC). The silane, phosphate and non-treated samples were tested in 3.5wt% NaCl solution in a cell of 20cm2 after 3h, 24h, 96h, 264h, 360h, 528h and 720h of immersion in the electrolyte solution. The results indicated that the silane pre-treated samples have shown the highest impedance modulus value even after 530h of immersion.Adherence and flexibility were also evaluated by tape test–X method–and conic mandrel test. The results have evidenced the superior adherence of the coating for the silane pre-treated samples. The SSC test revealed that the silane pretreated samples showed less blistered area around the scratch.In summary, the sulfursilane pretreated samples presented an overall better performance concerned to the corrosion resistance compared to phosphate and waterborne epoxy coated galvannealed steel samples.

Effects of Phosphate Dip Treatment on Quality of Rutilus frisii kutum Fillets During Ice Storage

The use of polyphosphates as a partial replacement of salt in different meat products to improve water holding capacity yield and retard oxidative rancidity has been noticed for many years. Therefore, in this study, effects of polyphosphates dip treatment in 5% solution with three different compounds of phosphate—including tetrasodium pyrophosphate (TSPP), sodium tripolyphosphate (STPP), and a mixture of them on kutum (Rutilus frisii kutum) fillets stored in ice was investigated for 18 days. Phosphate pretreatments showed desirable modal effects on fillets. In particular, the use of TSPP and the mixture of TSPP and STPP solutions were found to delay the fish fillet color changes and improved textural characteristics. An increase in water holding capacity accompanied with a decrease in hardness was observed in samples pretreated with polyphosphates. In total, the results indicated that dipping kutum fillets in polyphosphates solution was the most effective method to improve the quality properties of fillets during ice storage when compared with other phosphate-treated groups.