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The purpose of this paper is to study the process of coprecipitation of polyhydroxocomplexes of nickel and aluminum from solutions of nickel (Ni) (II) sulfate and aluminum (Al) (III) sulfate with caustic soda and to study the conversion process to nickel aluminate and to check its properties.

For the thermodynamic analysis of the precipitation process, the software package MEDUSA was used. The dependences of the electrical conductivity, pH and residual concentrations as functions of the OH/Me ratio were obtained. Using X-ray phase analysis, spectroscopic analysis and derivatographic analysis, the properties of the products obtained were studied. The effects of OH/Me ratio and molar ratio cation of reagents on the physicochemical properties of the products were analyzed.

The paper deals with the results of theoretical and experimental research on the synthesis pigments of blue and green colors based on Ni-Al spinel. The influence of the molar ratio cation content on optical and color characterise of pigments were studied.

The original complex method of studying the processes of co-precipitation of cations in the form of hydroxides is proposed. pH precipitation of aluminum hydroxide and nickel are different. It is interesting to study their co-precipitation. The resulting single-phase product is a precursor of nickel aluminate over a wide range of cation ratios. The dependences of the electrical conductivity, pH and residual concentrations as functions of the OH/Me ratio were obtained.

The aim of this paper is to research grease and additives' influence on fretting wear of mild steel.

Experiments were performed on a laboratory stand with contact conditions cylinder on flat. The mild steel couples were tested under dry conditions and lubricated with mineral and synthetic greases containing as additives: graphite, molybdenum disulphide, ZDDP and molybdenum dithiocarbamate in different concentrations.

The results revealed a significant influence of grease consistency and its welding load on the fretting wear of steel couples. Graphite and molybdenum disulphide were effective in a 10 percent concentration. ZDDP additive in a more than 1 percent concentration increased fretting wear. Molybdenum dithiocarbamate was not more effective than molybdenum disulphide powder. Grease lubrication of the fretted couple changed significantly the wear mechanism observed on SEM photographs of fretting scars.

The paper presents some indications of proper selection of grease for fretting prevention.

The influence of the main features of grease on fretting wear was confirmed on the basis of extensive investigation.

A mixed metal oxide-based spinel ceramic pigment has been successfully synthesized incorporating inorganic, high-temperature stable furnace cement as an inbuilt binder. Step by step synthesis was done for the spinel and cement mix formulations.

The pigment mix was synthesized by a solid-solid method where the inorganic binder was incorporated in the mix. The results suggested that CoCuMn-based spinel ceramic pigment with cement mix could be obtained at an annealing temperature of 1,100ºC for 1 h and the size, morphology and crystallinity of spinel mix were greatly influenced by the calcination temperature.

The pigment mix synthesized was applied as a coating to different substrates such as aluminum, glass and Mild steel. The results revealed that spectral selectivity of TSSS paint coatings based on the CoMnCu spinel ceramic mix was much better than that of solvent-based coatings for high-temperature applications. The presence of cement as an inorganic binder makes the functioning and application of paint easy as it becomes that of a waterborne type.

Ease of application, stability at high temperatures, best absorptivity at the solar selective spectrum and excellent adhesion properties for the selected surface are the key features of the designed pigment system. The applied pigment mix was studied as a coating to get the results for solar selective system.

The purpose of this study was to prepare colour pigments for use as spectrally selective coatings for solar absorbers.

Nano-particles cobalt and nickel oxides were prepared by sol–gel techniques. These oxides were prepared with its molar ratios and annealed at 200, 400, 600 and 800°C. The structure of the pigments was characterized by infrared spectrometer, differential scanning calorimetry analysis, X-ray diffraction, transmission electron microscope and scanning electron microscope.

Encapsulated cobalt and nickel oxides were completely formed at 800 and 600°C, and its colour was black and dark green, respectively. The results confirmed that black and green pigments combined selectivity with colour. Optical properties such as absorption and reflection were affected by the firing temperatures on cobalt and nickel oxides–gel polymers. All synthesized pigments consisted of nano-particles.

The prepared samples used in the present work were synthesized from cobalt chloride and nickel acetate. The salts were dispersed in polyacrylamide as a precursor.

The prepared metal oxides had good solar properties.

Colour becomes more important for thermal solar collectors, and it has attracted interest. This might be related to a generally growing attention towards architectural integration of solar energy systems into building. Architects would prefer different colours besides black, even if lower efficiency would have to be accepted.

This work aimed to prepare black transition metal oxide pigments to be used as solar absorbers in the solar selective and other industrial paints.

Mixed metal oxide CoCuMnO_x spinel pigments were synthesised via the sol‐gel route. These oxides, namely (I‐Co_0.50Cu_0.25Mn_0.25)O_x, (II‐Co_0.25Cu_0.50Mn_0.25)O_x and (III‐Co_0.25Cu_0.25Mn_0.50)O_x, were prepared with different molar ratios and annealed at 600, 800 and 900°C, respectively. The prepared oxides were characterised by infrared spectrometer (IS), differential scanning calorimetry analysis (DSC), X‐ray diffraction (XRD) and transmission electron microscope (TEM).

The prepared pigments have a spinel structure with the composition CoCuMnO_x. All synthesised pigments consisted of nano particles ranged from 10 to 80 nm. The optical properties showed high absorption and moderately low reflectance in the solar wavelength range.

The prepared samples, used in the present work, were synthesized from cobalt sulphate, copper chloride and manganese chloride. The salts were dispersed in polyacrylamide as a precursor.

The prepared samples were thermally stable and had good optical properties. They could be used as absorber materials in the painting of solar collectors.

These thermally stable mixed metal oxides could be used in the painting of solar collectors. The three mixed metal oxides could be used as absorber materials for heating solar collectors due to their high absorption and moderately low reflectance in the solar wavelength range.

The purpose of this paper is to evaluate the efficiency of acrylated guar gum (AGG) as an additive in alkyd resin for improved mechanical properties and to optimize the results of such an addition.

For studying the effect of AGG on coating properties, guar gum was modified to various degrees of esterification and various compositions of alkyd systems were made by incorporating different concentrations of AGG. The mechanical and solvent absorption of the unmodified and modified alkyd systems were characterized.

The incorporation of AGG into alkyd coating showed significant improvement of mechanical properties over the unmodified one. The modification caused an additional crosslink site through its unsaturation which led to increased crosslink density without phase separation of additive from the alkyd system which was confirmed by SEM scans.

The reactive additive, AGG used in the present study was synthesised using acryloyl chloride. Besides, it could also be synthesised from methacryloyl chloride and the effect of methyl substitution on water and solvent absorption could be studied.

The method developed provided a simple and practical solution to improving the mechanical properties of alkyd coatings.

The method for enhancing mechanical properties of cured alkyd system was novel and could find numerous applications in surface coatings.

The probability distribution of major length and aspect ratio (major length/minor length) of wear debris collected from gear oil used in planetary gear drive were analysed and modelled. The paper aims to find an appropriate probability distribution model to forecast the kind of wear particles at different running hour of the machine.

Used gear oil of the planetary gear box of a slab caster was drained out and charged with a fresh oil of grade (EP-460). Six chronological oil samples were collected at different time interval between 480 and 1,992 h of machine running. The oil samples were filtered to separate wear particles, and microscopic study of wear debris was carried out at 100X magnification. Statistical modelling of wear debris distribution was done using Weibull and exponential probability distribution model. A comparison was studied among actual, Weibull and exponential probability distribution of major length and aspect ratio of wear particles.

Distribution of major length of wear particle was found to be closer to the exponential probability density function, whereas Weibull probability density function fitted better to distribution of aspect ratio of wear particle.

The potential of the developed model can be used to analyse the distribution of major length and aspect ratio of wear debris present in planetary gear box of slab caster machine.

Dolomite is of immense importance for industrial applications. It is occuring in many locations in Egypt. Complete investigation and identification of the ore has been performed via chemical analysis and spectro‐photometric measurements using X‐ray fluroscence, X‐ray diffraction and electron microscope. The X‐ray diffraction pattern indicated that Egyptian dolomite is a crystalline material and electron microscope analysis showed that it has a lameller shape. Egyptian dolomite sample was evaluated as an extender pigment according to standard international specifications and proved to be excellent one for coating applications. Surface modification of dolomite ore particles has been carried out using stearic acid in cyclohexane. The modification concerned with the determination of adsorption isotherm, sediment volume, sedimentation rate, and dispersion properties to determine monolayer surface coverage of the ore particles. The unmodified and modified dolomite samples have been incorporated in anticorrosive primer formulations. The painted films were tested and examined in the laboratory accelerated corrosion test. Promising results were achieved and the films showed high performance as efficient extender pigment for coating applications that can replace satisfactorily its similar imported pigments.

Peanut skins are an agro-waste product with no commercial value. The purpose of this paper is to evaluate peanut skin as a natural dyestuff and to determine if this natural dye could be used in the dyeing of some Egyptian cotton cultivars.

The methodology consists of several steps; dye extraction procedure from peanut skin through aqueous extraction, then dyeing optimized using simultaneous mordanting using alum. Finally, dyed cotton has been subjected to different textile laboratory tests, for example, color measurements and mechanical properties. Color-fastness was determined on Egyptian cotton fabric. The peanut skin as a source of natural dye and the dyed cotton sample were characterized by fourier transform infrared spectroscopy (FTIR) analysis.

It was found that the natural dye extracted from peanut skin has an affinity for cotton samples and showed high dyeability with a unique color shade, good color strength and very good fastness.

The novelty of this paper is the extraction of color from the peanut's outer skin which is discarded as waste such as agro-waste of the agricultural process which can be used as a natural dye in the textile industry and applied to dyeing some Egyptian cotton fibers from different genotypes.

The purpose of this work was to perform a systematic study on the effect of formulation on the physical and mechanical properties of ultaviolet (UV) curable urethane acrylate resins. In addition, the authors wanted to derive mathematical formula for the prediction of physical and mechanical properties for the aforementioned system.

The experiments were carried out based on mixture experimental design to determine the effect of different multifunctional acrylates (i.e. 1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), trimethyolpropane triactylate (TMPTA)) concentration on the physical and mechanical properties of a UV curable polyurethane acrylate system. The urethane oligomer was synthesized and characterized by the research team. Microhardness, adhesion strength and scratch resistance of the cured films were evaluated as the physical and mechanical properties.

The results revealed that the resin and TMPTA concentrations had the most significant effects on the microhardness property. Adhesion strength of the films showed a linear trend with respect to all variables. Moreover, all components also had a significant and complex influence on the scratch resistance of the cured systems. In addition, mathematical equations proposed by mixture experimental design were derived for all the mentioned properties.

Other multifunctional acrylate monomers (i.e. more than three functional) can be used in the formulations. The kinetics of the curing can affect on the network formation and consequently on the properties of the cured films.

The obtained results can be used by the researchers who are active in the field of structure-property relationship of polymers and surface coatings. The reported data and the mathematical equations can also be used for the formulating of an appropriate formulation based on a specific application.

A systematic and statistical-based approach, i.e. mixture experimental design, was used to evaluate the effect of formulation on some of the properties of a UV curable polyurethane acrylate system. A urethane oligomer and three different multifunctional acrylate monomers as reactive diluents were used in the formulations. Noteworthy to mention that several mathematical models were derived by using analysis of variance for the prediction of the properties studied in this system.