Method for preparing nano-cobalt blue pigment CoAl2O4

Abstract

A method for preparing a nano-cobalt blue pigment CoAl2O4 belongs to the field of powder metallurgy preparation. The problems existing in the current cobalt blue pigment preparation are as follows: large pigment particle size, wide distribution, dark color, conglobation, and the like. The cobalt blue pigment CoAl2O4 powder material is characterized by 1:2 of Co-Al molar ratio, thereby forming pure-phase cobalt aluminum. The method for preparing the nano-cobalt blue pigment comprises the steps of: respectively dissolving acetic acid cobalt powder and aluminum sulfate powder in distilled water and then obtaining even clarified mixed solution by mixing, using a nitrogen spray gun to disperse the solution in liquid nitrogen for pre-freezing, later placing the liquid nitrogen in a freezedrier for conducting vacuum drying to obtain freeze-dried powder; and finally calcining the freeze-dried powder in air atmosphere for obtaining bright blue powder, namely the nano-cobalt blue powder. The method leads the cobalt and the aluminum to be mixed at the molecular order of magnitude and can decrease the firing temperature in the calcining process; moreover, as the powder crystal grain size is obviously refined without conglobation, the properties such as the reflectivity of the cobalt blue pigment and the like are improved.

Description

Technical field: [0001] A kind of nano cobalt blue pigment CoAl 2 o 4 The preparation method belongs to the field of powder metallurgy preparation. Background technique: [0002] Cobalt blue, a metal oxide miscible pigment with a spinel crystal structure, its simplest chemical formula is CoAl 2 o 4 , also known as cobalt aluminate. In general use, a certain amount of other metal ions are usually introduced to modify the cobalt blue pigment, so that mixed-phase pigments of different hues or shades can be prepared to meet the needs of cobalt blue pigments used in different environments. For example, doping with Mg 2+ When the amount is 0.5% to 1.0%, it will increase the reflectivity of the cobalt blue pigment at a wavelength of 439nm, but has little effect on the reflectivity at 600nm. [0003] The excellent performance of cobalt blue pigment is mainly reflected in its excellent weather resistance, acid and alkali resistance, high thermal stability and chemical stability...

AI Technical Summary

Problems solved by technology

[0004] The preparation of traditional cobalt blue pigments generally adopts the solid phase method, that is, the raw material salt is mixed and then directly calcined at a high temperature, or the oxides of Co and Al are mixed and then ball milled and then calcined at a high temperature. The general calcining temperature is higher than 1200 ° C. The disadvantages are not only The calcination temperature is high, the energy consumption is high, and the obtained pigment has a large particle size, wide distribution, dark color, and impurities are more likely to be mixed in during ball milling, which affects the performance of the pigment.

Although the liquid phase method can solve the problem of pigment color development, there is inevitably agglomeration phenomenon, and the raw materials required by the liquid phase method are generally expensive and the process is relatively complicated

[0005] The results of the literature survey show that the research on the preparation of nano-cobalt blue pigments by freeze-drying technology has not been reported at home and abroad so far.

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