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To investigate the effects of the temperature of synthesis and of the thermal treatment of zinc chromate on the properties of the zinc chromate pigments.

Zinc chromate pigments was prepared using zinc salt solution, sodium hydroxide and potassium dichromate solutions. The reaction temperature was varied in order to evaluate the effect of the reaction temperature on the properties of the pigment synthesised. The pigment obtained was heated to 10°C above the critical temperature in order to investigate the effect of thermal treatment on the pigment properties. SEM, XRD, XFR and STA were employed for the characterisation of the pigments synthesised.

Reaction temperature had a significant effect on the properties of the resulting pigment. Thermal treatment of the pigment caused the decomposition of the zinc chromate phase to ZnO, ZnCr₂O₄ and K₂CrO₄ phases. The glaze containing zinc chromate had satisfactory colour characteristics.

The study focused on the preparation and evaluation of zinc chromate as a substitute for praseodymium zircon in glaze. The study could be extended to investigation of similar inorganic pigment for similar purposes.

The information on the effects of the reaction temperature of pigment synthesis and of thermal treatment of the pigment is useful for industrial production of the pigment of satisfactory properties.

Novel use of zinc chromate as a lower‐cost substitute for praseodymium zircon in glaze and understanding of the effects of the production conditions on the properties of the resulting pigment and the glaze.

The purpose of this paper is to synthesize and characterize nano-ceramic blue pigment Co_0.5Zn_0.5Al₂O₄ via polyacrylamide gel method. Generally, the high cost and the environmental toxicity of cobalt aluminate pigments lead them to become less common and cause problems in production process. To significantly reduce this problem, it is required to reduce the cobalt in the pigment and replace the cobalt with some amounts of zinc in the structure.

In this paper, calcination temperature and its effects on phase specification and color properties of final product were investigated. The powders were studied by using XRD, FESEM, TG/DTA, FTIR, UV-Vis and colorimetric in CIELab space, in which the calcination temperatures were set to 600°C, 800°C and 1,000 °C, and the inert atmosphere was air.

According to the XRD patterns, single-phase spinel structure with a good crystallinity was formed even in the low temperature. The infrared spectra displayed vibrations at about 500, 560 and 680 cm⁻¹, which were ascribed to the spinel structure. FESEM images showed nanoscale particles with an average size of 32 nm. Regarding the Co²⁺ spin transitions in tetrahedral sites, the UV-Vis spectra presented three bands at 552, 598 and 628 nm.

The colorimetric data indicated the formation of blue pigments corresponding to negative values of b*. The color of pigments was affected by calcination temperature.

The characterization analysis shows that a blue pigment has been obtained in this research. Different degrees of blue color were obtained at different calcination temperatures.

Composite materials are replacing the traditional materials because of their remarkable properties and the addition of nanoparticles making a new trend in material world. The nano addition effect on tribological properties is essential to be used in automotive and industrial applications. The current work investigates the sliding wear behavior of an aluminum alloy (AA) 6061-based hybrid metal matrix composites (HMMCs) reinforced with SiC and B₄C ceramic nanoparticles.

The hybrid composites are fabricated using stir casting process. Two different compositions were fabricated by varying the weight percentage of the ceramic reinforcements. An attempt has been made to study the wear and friction behavior of the composites using pin-on-disc tribometer to consider the effects of sliding speed, sliding distance and the normal load applied.

The tribological tests are carried out and the performances were compared. Increase in sliding speed to 500 rpm resulted in the rise of temperature of the contacting tribo-surface which intensified the wear rate at 30N load for the HMMC. The presence of the ceramic particles further reduced the contact region of the mating surface thus reducing the coefficient of friction at higher sliding speeds. Oxidation, adhesion, and abrasion were identified to be the main wear mechanisms which were further confirmed using energy dispersive spectroscopy and field emission scanning electron microscopy (FESEM) of the worn out samples.

The enhancement of wear properties is achieved because of the addition of the SiC and B₄C ceramic nanoparticles, in which these composites can be applied to automobile, aerospace and industrial products where the mating parts with less weight is required.

The influence of nanoparticles on the tribological performance is studied in detail comprising of two different ceramic particles which is almost new research. The sliding effect of hybrid composites with nano materials paves the way for using these materials in engineering and domestic applications.

The aim of the work is to develop an anticorrosion pigment based on an oxide mixture with lamellar particles. The pigments are prepared from lamellar zinc, zinc oxide and magnetite by calcination. An alkaline earth carbonate is added when embedding a third cation in the lattice of the ferrite that forms the envelope of the lamellar zinc. The properties of the pigments are tested both in the powdered state and when embedded in an epoxy-ester system using different pigment volume concentrations (PVC).

The properties of paints containing synthesised oxide mixture-based pigments at various volume concentrations and with the Q factor – Q = PVC/CPVC = 0.65 – were examined (where CPVC is critical pigment volume concentration). A series of isometric ferrite pigments were also synthesised for a comparison. Paints of both types with PVC = 10, 15 and 20 per cent were formulated. Steel panels coated with the paints were subjected to corrosion and mechanical tests.

The oxide mixtures with lamellar particles were subjected to particle size analysis and found to make up a broad distribution curve. Electron microscopy photographs confirmed that the oxide mixture pigments contained lamellar particles with a surface layer. A high anticorrosion effect was achieved owing to the combination of different oxide types.

The properties of the oxide mixtures with lamellar particles are described. Their particle distribution curves can be obtained by particle size analysis methods with a view to obtaining additional information on the status and properties of the pigment particles that may be useful in the development of better paints/coating materials.

Oxide mixtures with lamellar particles can be used in paints protecting construction steel.

The composition of the prepared oxide mixture-based pigments is novel. Each oxide acts by its own anticorrosion mechanism and the final beneficial effect is due to their concerted action.

The purpose of this study is to evaluate the role of encapsulation pH and iron source on the anchorage mode and performance of iron oxide-encapsulated aluminium pigments.

The coloured waterborne aluminium pigments were prepared at pH 5-7.5 by using FeSO₄ and FeCl₃ as iron source. The anchorage mode of iron oxides on aluminium was characterized using optical microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Furthermore, the pigmentary performance was characterized through anticorrosion test and multi-angle spectroscopy.

Diaspore and boehmite could form from H₂O₂ oxidizing aluminium. Both low pH and FeSO₄ systems are beneficial for diaspore, inducing green rust anchor on the aluminium to form goethite. Either in FeSO₄ or FeCl₃ system, slightly high pH is beneficial for the formation of boehmite, which occurred together with ferrihydrite to form denser coating with yellowness and excellent anticorrosion property. At pH above 7, the formation of dendritic iron oxide is detrimental to the anticorrosion property and the glossiness.

Only FeSO₄·7H₂O and FeCl₃·6H₂O as iron sources were explored.

The investigation results provide theoretical basis to obtain excellent chromatic waterborne aluminium pigments.

The method for investigation of encapsulation mechanism by surveying the structure of iron oxides on aluminium, which varies with the pH of the system and iron sources, is novel.

The purpose of this paper is to develop hybrid aluminum metal matrix composite by stir casting process, reinforced with graphite and hard boron carbide particles to enhance the wear resistance. An attempt is made to optimize the wear (weight loss) and coefficient of friction (COF) by considering three factors, i.e. normal load, track diameter and sliding speed which were varied at three different levels.

The effect of graphite and boron carbide on microhardness was studied by adding them in varying percentages. After determining the best combination of hybrid reinforcements, optimization of wear (weight loss) and COF was carried out at various levels of considered factors. Taguchi design of experiments was used using the software “Minitab 16.1”. ANOVA was used to analyze the effect of various parameters on wear and COF. To validate the results, mathematical modeling was carried out in terms of regression equations and results obtained by regression equations.

The results revealed that the lower weight percentage of graphite (3 per cent) and boron carbide (1 per cent) significantly improved microhardness of developed composites. Results of ANOVA revealed that normal load was the main contributing factor for wear and COF. The results obtained by regression equations and confirmatory tests were within the results obtained by ANOVA.

To the best of the author’s knowledge, very less work has been reported on optimization of wear and COF using hybrid reinforcement particles of graphite and boron carbide.