Zinc Hydroxychloride Research Articles

Effects of Increasing Zn from Zinc Sulfate or Zinc Hydroxychloride on Finishing Pig Growth Performance, Carcass Characteristics, and Economic Return

Effects of Increasing Zn from Zinc Sulfate or Zinc Hydroxychloride on Finishing Pig Growth Performance, Carcass Characteristics, and Economic Return

EIS and XPS investigations on the corrosion mechanism of ternary Zn–Co–Mo alloy coatings in NaCl solution

The changes in composition of the corrosion products of electrodeposited ternary Zn–Co–Mo alloy coatings on AISI 1015 steel during exposure to 0.5moldm−3 NaCl solution were investigated. XPS studies demonstrated that at the initial stage of corrosion on the surface of Zn–Co–Mo coating zinc hydroxide layer is formed. Hydroxyl groups react with chloride and carbonate ions which lead to the formation of zinc hydroxy carbonates and zinc hydroxy chlorides. The share of these compounds in the oxidation products is initially large. However, with time zinc hydroxy compounds slowly changes to zinc oxide, which is more stable corrosion product. It was estimated that after 24h of exposure to NaCl solution nearly 60% of zinc detected on the surface of Zn–Co–Mo coating was present in the ZnO form, 18% in the form of zinc hydroxy chloride, and more than 21% as zinc hydroxy carbonate. XPS analyses revealed that the amount of zinc hydroxy chloride increases as the exposure time lengthens and it is significantly higher than at the surface of binary Zn–Co coating. The presence of crystalline zinc chloride hydroxide as a stable product of corrosion of ternary Zn–Co–Mo alloy coating in a 0.5moldm−3 NaCl solution was confirmed by XRD analysis. According to XRD and FTIR other zinc corrosion products like: ZnO, Zn(OH)2 and Zn5(CO3)2(OH)6 were also present. The results of XPS and EIS measurements allow us to assume that in the presence of Mo in the alloy, on the surface of ternary Zn–Co–Mo alloy (3.4wt.% Co, 2.7wt.% Mo) coating more zinc hydroxy chloride is formed, which favors higher corrosion resistance of this coating.

Morphological and structural modifications of chemically‐prepared emeraldine polyaniline and zinc oxide in PAni‐ZnO composite

AbstractIn this paper, the characteristic changes on the surface morphology and structure of both emeraldine polyaniline (PAni) and ZnO films in the chemically‐prepared PAni‐ZnO composite are presented. The PAni‐ZnO composite on amorphous glass substrate was fabricated utilizing chemical bath deposition technique. The ZnO films were first synthesized using appropriate amounts of zinc sulphate and ammonium hydroxide. Emeraldine form polyaniline films were then grown on as‐prepared ZnO films using appropriate amounts of aniline hydrochloride and ammonium peroxydisulphate. The formation of zinc hydroxychloride hexagonal‐plate structures in the composite film resulted to morphological and structural modifications of PAni and ZnO composite films. The highly‐crystalline emeraldine polyaniline became amorphous when deposited as part of the composite while increased tensile strain was observed for ZnO in the composite due to stretching‐effect caused by zinc hydroxychloride along the outward‐planar direction. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Simulating study of atmospheric corrosion of Zn–Ni alloy coating on steels in marine zone: Structure and properties of artificially synthesized Ni(II)-doped zinc hydroxychloride rust particles

To simulate the atmospheric corrosion of Zn–Ni alloy coating on the steel in marine zone, artificial Ni(II)-doped zinc hydroxychloride (Zn5(OH)8Cl2⋅H2O:ZHC) rust particles were prepared by hydrolysis of ZnO particles in a mixture of aqueous ZnCl2 and NiCl2 solutions at 85°C and were characterized by various means. Then, the Ni(II)/(Zn(II)+Ni(II)) atomic ratio in starting solution (XNi) was 0–0.10. XRD results indicated that crystallization of the layered structure of ZHC was strongly inhibited with an increase of XNi and no new particles were generated. The Ni(II) was incorporated into ZHC crystal by substitution with Zn(II) and the Ni/(Zn+Ni) molar ratio in the particles was almost consistent with XNi. The ZHC particles formed at XNi=0 were hexagonal plate with a size of ca. 3.2μm and a thickness of ca. 0.3μm. Increasing XNi reduced the size and thickness of ZHC particles. Besides, addition of Ni(II) suppressed the adsorption of CO2 and SO2 gasses on ZHC, because of layered structure of this material to be disintegrated. The foregoing results suggest that atmospheric corrosion of Zn–Ni alloy coating in marine zone forms dense and compact zinc rust layer composed of fine Ni(II)-doped ZHC particles with a low affinity to corrosive gasses on the steels, leading to the suppression of further corrosion of steel. Also, role of Ni on the atmospheric corrosion of Zn–Ni alloy coating in marine zone can be suggested by studying the structure and properties of artificial Ni(II)-doped ZHC rust particles.

ICP-AES and MicroRaman corrosion behaviour investigation on Zn4Sb3 and Al, Ag doped phases in sodium chloride solution

The high thermoelectric performance of the β-phase Zn4Sb3 has drawn much attention for its application in the intermediate temperature range. In this work we explore the corrosion behaviour properties of pure Zn4Sb3 compound and after partial substitution of Zn with Al and Ag. In particular, Zn4Sb3, (Zn1xAlx)4Sb3 and (Zn1xAgx)4Sb3 (x=0.01) compounds were synthesized using a muffle furnace and characterized in terms of crystal structure, morphology and phases composition (SEM-EDXS, XRD). All samples were placed in 0.1M NaCl aerated solution at room temperature for 48days. A study of the amount of cations released in solution was carried out using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) analysis. Analytical data reveal a higher value of zinc amount for doped samples. The microRaman spectroscopy analysis carried out on surface corrosion products revealed the presence of anhydrous and hydrate zinc hydroxy chlorides. No worsening on corrosion behaviour of Zn4Sb3 intermetallic compounds was observed after Al or Ag doping.

Precipitation of various shapes of nanosized zinc oxide from zinc chloride solutions by neutralization with MgO and Ca(OH)2 as non-transparent basic agents

Various shapes of nanostructured wurtzite-type ZnO including nanorods, needle-like nanorods and spherical nanoparticles were synthesized by a simple aqueous controlled-precipitation process. The precipitation process of ZnO was accomplished via the reaction between ZnCl2 solution and Ca(OH)2 and MgO suspensions at 85 °C for 1 h. With MgO, layered zinc hydroxychloride was precipitated as a precursor which was converted to zinc oxide by adjusting the pH value or calcination at 520 °C for 4 h. Using Ca(OH)2, ZnO was precipitated directly. One of the scopes of this study is to investigate the effect of solid particles of a non-transparent alkaline agent on the growth mechanism of the ZnO crystal. Nano spherical particles were produced by the addition of the zinc chloride solution into the basic suspension while, nanorods were obtained when the alkaline suspension was dropped into the zinc-containing solution. It can be concluded from the results that solid particles of a basic suspension can prevent the incorporation of the growth units into the crystal lattice of the ZnO nuclei when a zinc containing solution is dropped into a basic suspension.

Evolution of corrosion products and metal release from Galvalume coatings on steel during short and long-term atmospheric exposures

Non-treated Galvalume (55% Al, 43.4% Zn and 1.6% Si by weight) coatings have been studied through a combination of surface, near surface and bulk analysis after exposure at marine conditions, and for comparison also in an urban test site and in successively more complex short-term laboratory exposures. Slightly polished Galvalume surfaces exhibit dendritic aluminum-rich areas with higher Volta potential compared with interdendritic zinc-rich areas. These effects were not observed on bare as-received surfaces due to the overall presence of aluminum oxide. As a result, preferential corrosion occurred initially in interdendritic areas. The zinc release rate followed the same time-dependence as the surface coverage of zinc-containing phases at the marine exposure condition with zinc predominantly released compared to aluminum. Short term laboratory exposures generated the same main phases as formed at marine conditions. This confirms that the evolution of corrosion products and time dependence of zinc release rates can be explained by the uniform formation of less soluble Al2O3, AlOOH and Al(OH)3 compared to observed zinc-containing phases, e.g. ZnO, zinc hydroxycarbonate and zinc hydroxychloride. The same underlying mechanism is believed to operate also during exposure of Galvalume in the urban site studied.

Evaluation of Corrosion Behavior of Galvanized Steel Treated with Conventional Conversion Coatings and a Chromate-Free Organic Inhibitor

Conventional weight loss tests and both DC and AC electrochemical techniques were used to study if an organic inhibitor containing an alkanolamine salt of a polycarboxylic acid can substitute toxic coatings as chromating and certain phosphating procedures in the protection of galvanized steel. The electrolyte used was a 0.5 M aerated NaCl solution. All tests gave concordant results, indicating that the chromate-free organic inhibitor does protect galvanized steel in this environment, even though the provided protection was less than that of the chromate conversion coating. It was observed that, after a moderate initial attack, the corrosion rate diminishes due to the appearance and growth of passivating corrosion products layers, mainly constituted by zinc hydroxychloride and two varieties of zinc hydroxide, among other crystalline compounds.

Influence of anions on the formation and structure of artificial zinc rusts

To simulate the atmospheric corrosion of steels galvanized with Zn under different conditions, artificial zinc rusts of basic zinc salt (BZS) were prepared by hydrolyzing ZnO particles in aqueous solutions including ZnCl 2, ZnSO 4 and Zn(NO 3) 2. In ZnCl 2–ZnSO 4, ZnSO 4–Zn(NO 3) 2 and ZnCl 2–Zn(NO 3) 2–ZnSO 4 systems, zinc hydroxysulfate (Zn 4(OH) 6(SO 4)· nH 2O) was formed while zinc hydroxychloride (Zn 5(OH) 8Cl 2·H 2O) was generated in ZnCl 2–Zn(NO 3) 2 system. Zinc hydroxynitrate (Zn 5(OH) 8(NO 3) 2·2H 2O) was yielded in only Zn(NO 3) 2 system. All the formed artificial zinc rusts were hexagonal plate particles. These results suggest that SO x is the most effective corrosive gas on the formation of BZS rusts on galvanized steel.

Corrosion product formation on Zn55Al coated steel upon exposure in a marine atmosphere

The formation of corrosion products on Zn55Al coated steel has been investigated upon field exposures in a marine environment. The corrosion products consisted mainly of zinc aluminium hydroxy carbonate, Zn 0.71Al 0.29(OH) 2(CO 3) 0.145· xH 2O, zinc chloro sulfate (NaZn 4(SO 4)Cl(OH) 6·6H 2O), zinc hydroxy chloride, Zn 5(OH) 8Cl 2·H 2O and zinc hydroxy carbonate, Zn 5(OH) 6(CO 3) 2 were the first three phases were formed initially while zinc hydroxy carbonate Zn 5(OH) 6(CO 3) 2 was formed after prolonged exposure in more corrosive conditions. The initial corrosion product formation was due to selective corrosion of the zinc rich interdendritic areas of the coating resulting in a mixture of zinc and zinc aluminium corrosion products.

Structure and properties of Ti(IV)-doped zinc hydroxychloride rusts formed at various temperatures

To simulate the atmospheric corrosion of steels galvanized with Ti–Zn alloys under different atmospheric temperatures, Ti(IV)-doped zinc hydroxychloride (Zn 5(OH) 8Cl 2·H 2O: ZHC) was prepared at various aging temperatures of 6–120 °C. Adding the Ti(IV) inhibited the crystallization and particle growth of ZHC, showing a minimum at 50 °C. Higher aging temperature promoted the formation of TiO 2 nano-particles. Elevating the aging temperature suppressed the adsorption of H 2O and CO 2 on Ti(IV)-doped ZHC. These results suggest that the alloying Ti in galvanized steel forms compact zinc rust layer at various atmospheric temperatures in marine environment, which would lead to the enhancement of corrosion resistance.

Role of zinc compounds on the formation, morphology, and adsorption characteristics of β-FeOOH rusts

To simulate the corrosion of galvanized steel in marine zone, β-FeOOH was prepared by aging the FeCl 3 solutions containing ZnCl 2 and zinc rusts such as ZnO and zinc hydroxychloride (Zn 5(OH) 8Cl 2·H 2O:ZHC). Adding ZnCl 2, ZnO, and ZHC inhibited the crystallization and particle growth of β-FeOOH and the inhibitory effect was in order of ZHC ≈ ZnO > ZnCl 2. The adsorption of H 2O and CO 2 was suppressed by adding ZnCl 2, ZnO, and ZHC. These results imply that the rust formed on galvanized steel in marine environment is more compact, amorphous, and hydrophobic in nature which may lead to improve the corrosion resistance.

Chromate adsorption and pH buffering capacity of zinc hydroxy salts

Layered materials of zinc hydroxychloride (ZHC), zinc hydroxynitrate (ZHN) and zinc hydroxysulfate (ZHS) were prepared by the precipitation method. The products were highly crystalline. The pH buffering capacities of the products are high in the pH range from 3 to 10. The zinc hydroxyl salts have a high capacity for adsorbing chromate ions.

Influence of thermal treatment on the structure and adsorption properties of layered zinc hydroxychloride

Layered zinc hydroxychloride (Zn 5(OH) 8Cl 2·H 2O) synthesized by hydrolyzing the ZnO particles in aqueous ZnCl 2 solutions at 100 °C for 48 h was outgassed at different temperatures ranging from 100 to 250 °C for 2 h and the structure and adsorption properties of the products were examined by various means. Outgassing at 100–150 °C eliminated the H 2O molecules in interlayer of zinc hydroxychloride. The layered structure of zinc hydroxychloride was disintegrated at 175 °C by breaking the OH⋯Cl hydrogen-bond in interlayer to form curled thin films composed of poorly crystallized β-Zn(OH)Cl and ZnO, leading to the increment of the specific surface area from 4 to 39 m 2/g. The β-Zn(OH)Cl was decomposed at 225 °C to form ZnO. The crystallinity of ZnO was increased on elevating the outgassing temperature, giving rise to the UV absorption property. The H 2O and CO 2 adsorption measurements revealed that the zinc hydroxychloride outgassed at 100–150 °C possessed a high H 2O and CO 2 adsorption selectivity, and the selectivity diminished by the formation of thin films of ZnO above 175 °C.

Influence of Ti(IV) on the structure and properties of zinc hydroxychloride

Layered material of zinc hydroxychloride (Zn 5(OH) 8Cl 2 · H 2O: ZHC), which is one of the basic zinc salts (BZS), prepared from ZnO nano-particles aged with aqueous ZnCl 2 solutions containing TiCl 4 was examined by various means. The Ti/(Ti + Zn) atomic ratio ( X Ti) was ranged from 0 to 0.10. XRD results indicated that the diffraction intensity of ZHC was decreased with increasing X Ti. The ZHC formed at X Ti = 0 is hexagonal plate particles with ca. 4 μm in size and ca. 0.2 μm in thickness. The particle size was reduced by doping Ti(IV) and the irregular particles were generated at X Ti ⩾ 0.03. The Ti content was increased with increasing X Ti and Ti(IV) was more easily incorporated in the products than Zn(II). Diffuse reflection UV–vis results suggested that Ti(IV) in the products at X Ti ⩽ 0.01 is tetrahedral coordination and that at X Ti ⩾ 0.03 is a mixture of tetrahedral and octahedral ones. These facts prove that Ti(IV) inhibits the formation and crystal growth of ZHC. The specific surface area of Ti-doped ZHC estimated from N 2 adsorption isotherms was increased with increasing X Ti owing to the decrease of particle size. Contrary to the N 2 adsorption, H 2O monolayer adsorption capacity per unit surface area was reduced as X Ti increased. This seems that the layered structure of ZHC, which is accessible to H 2O molecules but not to N 2 molecules, is disintegrated by incorporation of Ti(IV). Similarly, adsorption of CO 2 on ZHC was inhibited by doping Ti(IV).

Hexavalent Chromium-Free Pre-Treatment for Galvanized Steel

The corrosion protection provided by an organic inhibitor containing an alkanolamine salt of a polycarboxilic acid that is suggested as non-toxic alternative to chromate and phosphate conversion coatings on galvanized steel was studied. Open circuit corrosion potential evolution, linear polarization, potentiodynamic polarization, electrochemical impedance spectroscopy, x-ray diffraction, salt spray (fog) tests and immersion - weight loss tests were used to evaluate the provided protection in a 0.5 M aerated NaCl solution. All tests gave concordant results, indicating that the chromate-free inhibitor does protect galvanized steel in this environment, even though the provided protection was less than that of the chromate conversion coating. It was observed that after a moderate initial attack, and except for the phosphated samples, the corrosion rate diminishes due to the appearance and growth of passivating corrosion products layers, mainly con stituted by zinc hydroxychloride (Zn5(OH)8Cl2•H2O) and two varieties of zinc hydroxide.

ChemInform Abstract: Synthesis and Characterization of Layered Zinc Hydroxychlorides.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and characterization of layered zinc hydroxychlorides

Layered material of zinc hydroxychlorides (Zn 5(OH) 8Cl 2· nH 2O: ZHC), which is one of the basic zinc salts (BZS), was synthesized from ZnO nano-particles aged with aqueous ZnCl 2 solutions at different temperatures ranging from 6 to 140 °C for 48 h. X-ray diffraction (XRD) results indicated that the diffraction peaks of ZnO completely disappeared by aging at 6 °C and the ZHC peaks were developed. By increasing the aging temperature, crystallinity of the layered structure was improved. At 6 °C, the ZHC particles were thin hexagonal plate particles with sizes ranging from 1 to 3 μm. The particle size of ZHC was independent of aging temperature. The atomic Cl/Zn ratios of all the ZHC materials were almost 0.2 less than 0.4 of the theoretical ratio, indicating that the synthetic ZHC is Cl-deficient. It seemed that half of Cl atoms in the layer were replaced with HCO 3 − and/or OH −. The specific surface areas of ZHC estimated from N 2 adsorption isotherms were ca. 10 m 2 g −1 and were independent of the aging temperature. However, the H 2O monolayer adsorption capacity per unit surface area ( n w) for all the samples was higher than that of ZnO particles, revealing the high affinity of ZHC to H 2O molecules. The n w values were increased by reducing the crystallinity of ZHC. This enhancement of H 2O adsorption selectivity was thought to be related with less-crystallized parts of the particles.

Performance of zinc phosphate coatings obtained by cathodic electrochemical treatment in accelerated corrosion tests

The formation of zinc phosphate coating by cathodic electrochemical treatment and evaluation of its corrosion resistance is addressed. The corrosion behaviour of cathodically phosphated mild steel substrate in 3.5% sodium chloride solution exhibits the stability of these coatings, which lasts for a week's time with no red rust formation. Salt spray test convincingly proves the white rust formation in the scribed region on the painted substrates and in most part of the surface on unpainted surface. The protective ability of the zinc corrosion product formed on the surface of the coated steel is evidenced by the decrease in the loss in weight due to corrosion of the uncoated mild steel, when it is galvanically coupled with cathodically phosphated mild steel. Potentiodynamic polarization curves reveal that E corr shifts towards higher cathodic values (in the range of −1000 to −1100 mV versus SCE) compared to that of uncoated mild steel and conventionally phosphated mild steel substrates. The i corr value is also very high for these coatings. EIS studies reveal that zinc dissolution is the predominant reaction during the initial stages of immersion. Subsequently, the non-metallic nature of the coating is progressively increased due to the formation of zinc corrosion products, which in turn enables an increase in corrosion resistance with increase in immersion time. The zinc corrosion products formed may consist of zinc oxide and zinc hydroxychloride.

Coating electroaccretion on galvanized iron and aluminum in seawater

Coating electroaccretion on galvanized iron and aluminum 1100 under cathodic polarization in artificial and natural seawater was investigated through electrochemical tests and optical imaging techniques. Biofilm affects the current density and the morphologies of gas evolution, particularly the maximum size of the gas bubbles and the interaction between gas evolution and calcareous deposit. Coating mineral composition is related to the type of metallic material and can be different according to growth in natural or artificial seawater. On galvanized iron in ASTM and natural seawater at potential <−1.2 V versus Ag/AgCl, coating is composed of aragonite and brucite as calcareous deposits on pure iron, aragonite forming before the growth of brucite. Even when coupled to a magnesium anode, the zinc layer can corrode and large aggregates of brucite and aragonite form on the bare steel. Coatings are composed of zinc hydroxychloride Zn 5(OH) 8Cl 2·H 2O and aragonite without brucite if electroaccretion is performed in natural seawater at potential >−1.2 V versus Ag/AgCl. Coatings grown on aluminum 1100 are different from those on galvanized iron. In ASTM seawater, the coating on aluminum 1100 is composed of aluminum oxide and Mg 4Al 2(OH) 14·2H 2O; in natural seawater, only of aluminum oxide. On specimens coupled with magnesium anode, the coating does not contain brucite and is composed of aragonite with Mg 6Al 2(OH) 18·4H 2O islands.