Iron Oxide Pigments Research Articles

Preparation and evaluation of nanosized mixed calcium iron oxide (CaFe2O4) as high heat resistant pigment in paints

Purpose– The purpose of this paper was to prepare and evaluate a nanosized mixed calcium iron oxide as a high heat-resistant pigment. Heat-resistant pigments can be defined as chemical substances that impart color to a substrate or binder and retain their color and finish at elevated temperatures. Mixed metal oxides have been widely used as pigments in coating formulations.Design/methodology/approach– This work presents synthesis of nanosized calcium iron oxide as an inorganic pigment by using simple synthesis technique, namely, solid-state calcination method, to study its heat and corrosion resistance. The prepared pigment was characterized by using X-ray diffraction, infrared spectroscopy, scanning electron microscopy and inductive coupling plasma. It was incorporated into paint formulations, and the heat, corrosion and mechanical resistance of dry paint film was evaluated.Findings– In this work, the prepared calcium iron oxide pigment showed excellent heat and corrosion resistance.Research limitations/implications– Heat-resistant coatings are required for industrial applications, mainly for reactors, exhaust pipes, space craft, stacks and similar equipments that are permanently and occasionally exposed to elevated temperatures. It was previously quite difficult to formulate heat-resistant organic coatings because of binder deficiencies; new vehicles for such applications are now available. Thus, the development of silicon resins has markedly advanced the utility of heat-resistant paints. High-temperature pigments are inorganic chemical compounds that impart and retain their color and finish to a substrate or binder at elevated temperatures.Practical implications– The nanosized mixed calcium iron oxide could be used as a pigment in paint formulations. It was found that it significantly enhances the heat, corrosion and mechanical resistance. It can also find numerous applications in other paint formulations for surface coating.Originality/value– The paper shows how the pigment consisting nanosized mixed calcium iron oxide could be used in heat-resistant paint formulations for coating metal surfaces.

Synthesis and characterization of iron oxide pigments through the method of the forced hydrolysis of inorganic salts

Iron oxide hydroxides were synthesized through forced hydrolysis of iron (III) chloride hexahydrate and iron (III) nitrate nonahydrate that as a function of temperature yield different phases characterized by their colors. The tonalities were related to the chemical composition as well as particle size as shown through energy dispersive spectroscopy, thermogravimetric analysis and dynamic light scattering. Iron chloride yielded Akaganèite with different opaque yellow tonalities and a mean particle size of196 (50 °C), 253 (70 °C), 235 (90 °C) and 170 nm (110 °C). The nitrate precursor yielded Goethite with yellow tonalities and particle size of 360 (60 °C) and 318 nm (70 °C), and Hematite with red tonalities and particle size of 262 (90 °C) and 261 nm (110 °C). The test dispersion and coloring of the white paint (water-based) showed an effective coating capacity, chemical and physical stability of the dispersant and iron pigments.

Production of black iron oxide from red mud

Production of inorganic pigments was studied, and specifically that of iron oxide black pigment, which can be used in paint-and-varnish industry and in manufacture of building and other pigmented materials. Results are presented of phase and chemical analyses of raw materials and final product. A technological scheme is suggested and production parameters of the black pigment from red mud are recommended. The pigment is produced from the −0.045 mm fraction of red mud, a waste from alumina industry. It is recommended to perform calcination at 850°C in a controlled atmosphere with deficiency of oxygen. This method yields an iron oxide pigment of purely black color with a coverage power of 8–10 g m−2 from a waste produced in manufacture of alumina, red mud (up to 90%), without additional additives and provides reduction of Fe(III) to Fe(II) by the sulfide sulfur present in the starting mud.

Novel environment friendly inorganic red pigments based on Bi4V2O11

Novel inorganic red pigment, (Bi0.92Zr0.07Al0.01)4V2O11.34, was successfully synthesized as an environmental friendly inorganic material, and its red hue was much higher than that of a commercial iron oxide pigment.

Lanxess enhances capabilities of new pigments plant in China

Speciality chemicals group Lanxess is responding to the high level of demand for iron oxide pigments by strengthening its production network in China. The company is adding a mixing and milling plant at the site of its new production facility for iron oxide red pigments in Ningbo, which is still under construction [ADPO, March & September 2013]. The additional plant increases the total investment at the Ningbo site from around €55 million to €60 million.

Effectiveness of organic and inorganic pigments for mass colouration of thermo-mechanical pulp used in wood–plastic composites

At present, to provide wood–plastic composites (WPC) with colouration and UV-protection, pigments are added in powder form or pre-dispersed in a polymer matrix (masterbatch) during compounding. Usually, the wood particles are not coloured prior to compounding, although this may improve the colour stability of the WPC. In this research project, two types of pigments were used to pre-colour thermo-mechanical pulp: an aqueous inorganic pigment preparation based on iron oxide and a water-based preparation of organic and inorganic pigments. Pre-coloured fibres were mixed with high-density polyethylene and maleic-anhydride grafted-PE in a kneading mixer and injection-moulded. As a reference, uncoloured fibres were mixed with pigments. Colour stability of the WPC was determined as ΔE* after 400 h of Xenon weathering. Pre-treatment of the fibres alone was not sufficient to improve colour stability of WPC. However, the use of fibres pre-treated with inorganic iron oxide pigments in combination with a pigment masterbatch to colour the polymer matrix resulted in a significant reduction of ΔE* compared to when either pre-coloured fibres only or uncoloured fibres plus pigment were used. The mixture of organic and inorganic pigments was less effective in improving colour stability than the application of inorganic pigments only. Flexural strength and modulus of elasticity of WPC with coloured fibres were slightly reduced compared to WPC with uncoloured fibres. Water uptake was higher for WPC with organic pigments than for WPC with inorganic pigments only. Fibre pre-colouration appears useful to obtain WPC with low colour change as a result of weathering.

The Value of Influence of Vibrations of the Chemical Composition of Technogenic Waste on Properties of Pigments

Influence of possible fluctuations of a chemical composition of waste of galvanic productions on the mixed iron oxide pigment (MIP) main pigmentary properties is established. It is shown that introduction of samples of MIP with the raised content of these or those metals in such industrial paintwork materials as alkyd PF-115 enamel and a primer GF-021, practically doesn't change physic-mechanical properties and firmness of the coverings received on their basis. It allows to apply slimes of galvanic productions as the main raw materials by industrial production of MIP and to reduce prime cost of a pigment by 15-20%.

Use of iron oxides to influence the weathering characteristics of wood surfaces: a systematic survey of particle size, crystal shape and concentration

Iron oxide pigments may be an alternative treatment for limiting weathering of wood surfaces instead of stains or clear coatings. An earlier study suggested the ability of iron oxides to protect against discoloration varied with particle size. In this study, iron oxides with different crystal shapes and particle sizes were investigated along with a carbon black pigment. Loblolly pine (Pinus taeda L.) samples were impregnated with water borne iron oxide dispersions, exposed to predetermined amounts of solar radiation in the high desert of Eastern Oregon, and then evaluated for discoloration, checking and changes in chemical composition. The results from this observational study suggest that much higher levels of iron oxide are required than previously thought to prevent discoloration and limit lignin degradation. Large particle sizes led to greater opacity and provided greater protection, but no iron oxide protected as well as carbon black. The findings also suggested that iron oxides had no effect on checking, indicating that the mechanisms of discoloration and checking were not directly related.

Surface modification of iron oxide (Fe2O3) pigment particles with amino-functional polysiloxane for improved dispersion stability and hydrophobicity

Purpose – The purpose of the present study is to use an amino-functional polysiloxane for the surface modification of red iron oxide (Fe2O3) pigment particles for their improved dispersion stability and hydrophobicity and to study the chemical interactions of polysiloxanes with the particle surface. Design/methodology/approach – Surface-treated red Fe2O3 pigment particles were prepared by treatment of the particles with different quantities of the (aminopropylmethylsiloxane)-dimethylsiloxane copolymer in concentrated suspensions in water. The samples were analysed with different instrumental and spectroscopic techniques to study the interaction of the polysiloxane with the particle surface and the effect of the surface treatment of the particles on their dispersion stability and hydrophobicity. Findings – Chemisorption of the amino-polysiloxane onto the surface of Fe2O3 particles resulted in stable layers which turned out to be helpful in improving greatly the dispersion stability of the particles as shown by the Static Light Scattering and Dynamic Light Scattering results. Formation of a polysiloxane coating onto the surface of the pigment particles was confirmed by studying the interactions of the polymer molecules with Fe2O3 surfaces by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy techniques. Practical implications – The surface-treated red Fe2O3 particles with improved dispersion stability can be important components of various formulations in applications such as the colouring of the cement or inorganic pigment-based paint formulations. Originality/value – The study provides mechanistic insights about the interactions of amino-polysiloxane with the red Fe2O3 particles. The process of surface modification of red Fe2O3 particles with the amino-functional polysiloxane showed increased hydrophobicity and dispersion stability which is an important requirement of the pigment-based formulations in real applications.

Prehistoric pigment characterisation of the Abri Pataud rock-shelter (Dordogne, France)

Iron oxide pigments found in archaeological context constitute an important source of information for the understanding of cultural and subsistence activities of ancient human cultures. In order to complete archaeological contextual information, many analytical methods have been applied to characterise pigments and to provide further information on this material (<em>e.g.</em> supplies, selections, mechanical or physical transformations of raw material, use and application processes). Several studies have demonstrated that the elemental composition of iron oxide pigments can be used to discriminate between several geological provenances. In this study, non-destructive micro-particle induced Xray emission analysis was applied in order to distinguish different kinds of reddish pigments from the prehistoric site of Abri Pataud, more especially from the Layer 2 attributed to Final Gravettian period (22,000 BP). By using an external beam, this technique required no sampling, and enabled us to perform localised analyses directly on raw material, on ochre residues applied on artefacts or on fragments of the wall of this rock-shelter. The results obtained by this technique demonstrate that the pigments covering the decorated fragments of the rock-shelter wall, found during the excavation of the Layer 2, have elemental compositions similar to the composition of a raw pigment found in the same layer. These results suggest that the shelter was decorated during the Final Gravettian period and thus provide new insights for the understanding of the archaeological context of this occupation layer.

Using high-temperature mechanochemistry treatment to modify iron oxide and improve the corrosion performance of epoxy coating – I. High-temperature ball milling treatment

This study achieved the surface modification of iron oxide pigment by using epoxy resin with high-temperature ball milling device. The compatibility of the modified iron oxide with the epoxy resin and the corrosion protection of epoxy coatings containing the modified iron oxide were investigated. The results show that the epoxy resin molecules grafted on the surface of the iron oxide, and the improved compatibility of the modified iron oxide with the epoxy resin lessens the interface defects between the iron oxide particles and the epoxy resin and enhances the corrosion resistance of the coating.

Anticorrosion properties of an epoxy zinc-rich composite coating reinforced with zinc, aluminum, and iron oxide pigments

The effects of lamellar aluminum (Al) and micaceous iron oxide (MIO) pigments on the anticorrosion properties of an epoxy zinc-rich coating were studied. To this end, the epoxy zinc-rich coatings containing 70% w/w spherical Zn particles, 60% w/w Zn + 10% w/w MIO, and 60% w/w Zn + 10% w/w Al were prepared. The electrochemical noise (ECN), potentiostatic polarization technique, and salt spray test were employed in order to investigate the anticorrosion performances of the zinc-rich coatings. The zinc-rich coatings morphologies were studied by scanning electron microscope (SEM) before and after the salt spray test. The open-circuit potential values were also measured at different immersion times. Results showed that MIO particles could enhance the cathodic protection duration of the zinc-rich coating by enhancing its barrier properties and reducing the zinc particles oxidation rate. It was also shown that Al particles reduced zinc-rich coating sacrificial behavior at short immersion times and increased it at long immersion times. Unlike MIO particles, Al particles behaved both as barrier and sacrificial pigment.

Three-dimensional analysis of the spatial distribution of iron oxide particles in a decorative coating by electron microscopic imaging

The three-dimensional (3D) spatial structure of an iron oxide containing alkyd paint specimen has been investigated by serial block-face scanning electron microscopy (SBFSEM). The resultant images of the 3D structure clearly present the spatial distribution of the iron oxide pigment particles in the coating film and reveal the extent of aggregation of the particles in the matrix material. More than one-half of the iron oxide particles (in volume) had aggregated to form clusters of considerable sizes that follow a Gaussian spacing distribution in the measured coating film. Over 80% of the clusters have dimensions between 1.5 μm and 3.5 μm; also, pores are evident at the centres of clusters whose sizes are larger than 2 μm. The work demonstrated here reveals a new approach to fully characterize the 3D spatial structure of coatings and to explore their correlations with the performance of the materials.

Competitive adsorption of (phosphorylated) ethoxylated styrene oxide polymer and polyacrylic acid on silica coated iron oxide pigment

The colloidal stabilization in waterbased paint is poorly understood due to its complexity in composition, usually containing mixtures of particles and of surface active agents (“dispersants”). In this study we make a step forward by analyzing the competitive adsorption of a few widely used dispersants on a typical inorganic pigment (70nm sized Fe2O3-based red pigment; surface treated with silica; negative zetapotential at pH∼7). The supposition is that any particle type in paint needs sufficient adsorbed dispersant in order to be stable. Thus, we investigate, for two combinations of two dispersants, how they mutually affect their adsorption at that pigment. Also the “single” adsorption of these dispersants was investigated, thus in the absence of the other. The dispersants are an anionic, polyacrylic acid sodium salt (“PANa”; MW=15,000Da) in combination with a MW=1500Da blockcopolymer of styrene oxide (SO) and ethoxylene (EO), either or not endcapped by a phosphate group (P). The adsorption behavior was analyzed by size exclusion chromatography of the processed supernatant of the pigment dispersion. PANa and SO–EO–P adsorb for electrostatic reasons while SO–EO has affinity only to an organic surface. PANa and SO–EO–P show regular single adsorption with a plateau starting at the critical micelle concentration (cmc). SO–EO shows single adsorption only beyond its cmc based on the adsorption of full micelles. When in competition, with SO-EP-P/PANa the adsorption of SO–EO–P is lowered by ∼65% while that of PANa is unchanged. With SO–EO/PANa the surface active species behave like in single adsorption below the cmc, but beyond the cmc a complicated phase separation occurs that cannot be based on mixed micelles. The adsorption data of PANa are compromised by depletion of PANa from interstices between particles. The anionic dispersants adsorb to the silicium oxide coated iron oxide pigment with negative surface potential because of the presence of a pH dependent relatively small number of positive iron oxide surface sites.

Production of Yellow Iron Oxide Pigments by Integration of the Air Oxidation Process with Bipolar Membrane Electrodialysis

To resolve problems with the traditional air oxidation process for producing yellow iron oxide pigments, an integration of bipolar membrane electrodialysis (BMED) with the air oxidation process was proposed. Before the integration, both the individual air oxidation process and the BMED process were investigated. The matching conditions for the integration were found to be as follows: pH = 2.5–2.8, FeSO4 concentration = 50–75 g FeSO4·7H2O/L, current density = 60 mA/cm2, distilled water flow rate = 0.3 L/h, etc., under which all the products generated were qualified as the same as those of the individual production process. In addition, economic evaluation of the integration was conducted. Even though the process cost is not as low as expected, it can achieve “zero waste discharge” because the produced inorganic base can be directly used in the air oxidation process and the cogenerated acid can be used in pickling industries. In conclusion, the integration is a feasible, effective, and environmentally frien...

New technology for recyclingmaterials from oily cold rollingmill sludge

Oily cold rolling mill (CRM) sludge is one of metallurgical industry solid wastes. The recycle of these wastes can not only protect the environment but also permit their reutilization. In this research, a new process of “hydrometallurgical treatment + hydrothermal synthesis” was investigated for the combined recovery of iron and organic materials from oily CRM sludge. Hydrometallurgical treatment, mainly including acid leaching, centrifugal separation, neutralization reaction, oxidizing, and preparation of hydrothermal reaction precursor, was first utilized for processing the sludge. Then, micaceous iron oxide (MIO) pigment powders were prepared through hydrothermal reaction of the obtained precursor in alkaline media. The separated organic materials can be used for fuel or chemical feedstock. The quality of the prepared MIO pigments is in accordance with the standards of MIO pigments for paints (ISO 10601-2007). This clean, effective, and economical technology offers a new way to recycle oily CRM sludge.

Huntsman Takes A Spin With TiO

Continuing a shake-up in the titanium dioxide pigment industry, Huntsman Corp. has agreed to acquire Rockwood Holdings’ business in TiO2 and several other chemicals. Huntsman plans to combine the Rockwood businesses with its own TiO2 operation and then unload the combination in a public stock offering by 2016. The purchase will cost Huntsman $1.1 billion plus $225 million in Rockwood pension obligations. The businesses employ about 3,300 people worldwide and had sales last year of $1.5 billion. The deal includes operations in iron oxide pigments, wood preservatives, water treatment chemicals, and elastomers; but titanium dioxide, at 66% of sales, is clearly the focus. By combining the Rockwood titanium dioxide business with its own, Huntsman will create the world’s second-largest TiO2 producer after DuPont. TiO2, a white pigment added to almost every can of paint, has become something of a hot potato for Huntsman, Rockwood, and DuPont. It’s a commodity chemical ...

Investigation of corrosion protection afforded by inorganic anticorrosive coatings comprising micaceous iron oxide and zinc dust

The present study deals with the investigation of the effects of partial replacement of sacrificial zinc dust by high efficiency barrier micaceous iron oxide (MIO) pigments on the corrosion protection behaviour of inorganic zinc rich coatings. To this end, waterborne zinc rich silicate paints based on nanosilica modified potassium silicate were formulated with different contents of zinc and MIO. After being applied on carbon steel panels, the coatings were evaluated by electrochemical impedance spectroscopy, corrosion potential measurements and salt spray test. Replacement of zinc by MIO in the formulation of zinc rich paints was revealed to shorten the duration of cathodic protection stage while on the other hand giving satisfactory results in 1000 h of salt spray test. It was concluded that the incorporation of MIO pigments in conjunction with zinc into the formulation of inorganic zinc rich coatings is a potential means to control the reactivity and the barrier protection stage.

Cathay Industries, Tonghua form jv to build iron oxide pigments plant

Hong Kong-based iron and chrome oxide pigments producer Cathay Industries Group is joining forces with chemical manufacturer Tonghua Group to build a new, state-of-the-art production plant for yellow, red and black iron oxide pigments in Tongling, in China's Anhui Province. The joint venture facility will have a stage-one capacity of 100 000 tonnes/year. Expansion to 150 000 tonnes per year is expected in stage two of the planned development.

Lanxess to construct new red iron oxide pigment plant in China to expand production network

Lanxess to construct new red iron oxide pigment plant in China to expand production network