SPECTROPHOTOMETRIC COLOR DETERMINATION OF CERAMIC PIGMENTS FOR CONSTRUCTION CERAMICS AND REGIONAL INNOVATION SYSTEM

The purpose of this work is the spectrophotometric determination of the color of ceramic pigments for the development of technology for the production of high-quality ceramic paints of a wide color palette for decorating building ceramics, porcelain and faience products. In this regard, using the principles of heterovalent isomorphic substitution of atoms in crystals, the compositions of ceramic pigments were designed on the basis of the anorthite derivatives containing transition elements with the general formula Са1-хMexAl2+xSi2-xО8, where calcium and silicon ions were replaced by aluminum and transition element, Ме – Cо, Ni, Fe, Cr. The color characteristics were taken on the UV-2600 spectrophotometer with «UV Probe» software. Measurement of wavelengths was in the range of -220-1400 nm. For Fe3+ with tetrahedral coordination, the brown color is due to the d–d transition. The absorption wavelengths of the samples corresponded to 758-283 nm. Со2+ is characterized by a coordination number of 4, the wavelengths of the absorbed light are 1328, 776, 625, 551, and 408 nm. In this case, the brightness varies from 5 to 64%. The color of the samples is violet-blue. For the yellow-green complex [NiО6], the absorption bands are located at ⅄ = 894, 693, 622, 385. The absorption spectra of chromium-containing pigments are characterized by the presence of maxima in the region of 536, 408, 310 nm, which corresponds to the green region of the spectrum

Structural characterization and colour of Ni3−xCuxP2O8 (0 ≤ x ≤ 3) materials

The structural characterization of Ni3−xCuxP2O8 (0.0 ≤ x ≤ 3.0) compositions was performed and the colour parameters of these materials measured. Solid solutions with Ni3P2O8, Ni2CuP2O8 and Cu3P2O8 structures were obtained and the compositional range in which they are formed was established. Structural distortion was detected in these solid solutions when x increases from the variation in the unit cell parameters and that of the interatomic distances. Solid solutions with Ni3P2O8 structure are stable at 1200 °C and may be used as ceramic pigments. Changes in the colour of these materials were related to the structural changes. Yellow materials are obtained from Ni3−xCuxP2O8 solid solutions with a Ni3P2O8 or Ni2CuP2O8 structure and a gradual change from yellow to brown is obtained with the introduction of Cu(II) in the Ni3P2O8 structure, 0.0 ≤ x ≤ 0.7 at 1200 °C.

Novel yellow to blackish green Ni-doped aluminium titanate ceramic pigments

Novel yellow to blackish green Ni-doped aluminium titanate (Al2TiO5) ceramic pigments were synthesized by solid-state reaction method at 1400 ?C. Effects of nickel doping content on phase composition, microstructure, optical properties and stability were studied. The results show that the higher content of Al2TiO5 phase and the reduction of the lattice distortion of aluminium titanate could be attributed to the entry of nickel ions into aluminium titanate lattice resulting in the formation of solid solution. Ni-doped aluminium titanate ceramic pigments show exceptional glaze colouring and are expected to be promising high-temperature pigments.

Synthesis and characteristics of aluminate spinel ceramic pigments based on spent aluminium-cobalt-molybdenum catalyst

Purpose The purpose of this paper is to conduct the directed synthesis of blue-colour aluminate spinel pigments based on spent aluminium–cobalt–molybdenum (ACM) catalyst and to study peculiar features of mineral formation processes and changes in their colour indices depending on composition and firing temperature. Design/methodology/approach Aluminate spinel ceramic pigments with specified colour indices were synthesised by directed formation of their mineral composition and identification of the most rational technological parameters of production. Mineral composition of synthesised pigments was evaluated by X-ray phase analysis. The colour indices of pigments and pigment-containing glaze coatings were studied on the comparator colour. The chemical resistance of pigments was determined by loss of their weight loss after boiling in 1 N hydrochloric acid solution and 1 N sodium hydroxide solution. Findings Peculiar features of formation of the mineral composition of aluminate spinel pigments based on the ACM catalyst were studied. The expediency of using magnesium and zinc oxides in their composition has been proved. It is found that for the formation of stable pigments of intense blue colour, a concentration of cobalt (II) oxide in the amount of 0.5 mol is sufficient, which is 23.1 Wt.%. The colour of such pigments is determined by the ratios of cobalt, magnesium and zinc aluminates, which form a spinel solid solution. Practical implications The use of developed aluminate spinel pigments provides obtaining of high-quality glass coatings of blue colour, in particular, for ceramics. Originality/value Aluminium oxide in the spent ACM catalyst is predominantly in the active form (of amorphous aluminium hydroxide and y-Al2O3). This is a prerequisite for the use of this waste material as a complete substitute for chemically pure Al2O3 in the technology of aluminate spinel pigments and reduction of their firing temperature. Besides, spent ACM catalyst already contains 5 Wt.% of expensive cobalt (II) oxide in the form of stable colour-bearing phase CoAl2O4.