A method for preparing tricalcium aluminate using spark plasma sintering technology

Abstract

The invention relates to a method for preparing tricalcium aluminate by the aid of spark plasma sintering techniques. The method includes analyzing raw materials which are pure calcium carbonate CaCO3 and pure gamma-phase aluminum oxide gamma-Al2O3; carrying out ball-milling on the pure calcium carbonate and the pure gamma-phase aluminum oxide and then controlling the heating rates and the cooling rate of a spark plasma sintering furnace under the conditions of vacuum degrees of (30-50) Pa, pulse ratios (ON / OFF) of (6 / 1-48 / 8) and axial pressures of (1-3) kN; fetching samples out of the spark plasma sintering furnace when the temperatures of the samples are reduced and reach (60-90) DEG C and grinding the samples to obtain particles with the sizes smaller than 20 micrometers so as to obtain the tricalcium aluminate. The method is simple and convenient, and the synthesis efficiency is improved by (10-20) times as compared with the traditional method. The method has the advantages of speediness, high efficiency and energy conservation.

Description

technical field [0001] The invention belongs to the technical field of building materials, and in particular relates to a method for preparing tricalcium aluminate by using a discharge plasma sintering technology. Background technique [0002] The mineral phases in Portland cement clinker are mainly tricalcium silicate, dicalcium silicate, tricalcium aluminate and tetracalcium aluminoferrite. By mass, tricalcium aluminate (3CaO·Al 2 o 3 , referred to as C 3 The content of A) is generally (7-15)%, which is the third largest mineral phase of Portland cement clinker, only slightly higher than tetracalcium aluminoferrite. Although the proportion is small, in the process of clinker calcination, tricalcium aluminate can reduce the melting temperature and viscosity of clinker, which is beneficial to the formation of tricalcium silicate, and is indispensable in the production process of cement industry. and a product of avoidance. [0003] Tricalcium aluminate has the character...

AI Technical Summary

Problems solved by technology

The raw materials used in the solid phase sintering method are mainly CaO, Al 2 o 3 , Ca(OH) 2 , Al(OH) 3 Such as powder, there are disadvantages such as uneven mixing of reactants, high calcination temperature, long time, high energy consumption, and difficult ion diffusion. At least three times of repeated grinding and calcination are required to ensure that the product has a high purity.

The sol-gel method aims at the above shortcomings of the solid-state sintering method, using calcium nitrate Ca(NO 3 ) 2 4H 2 O, aluminum nitrate Al(NO 3 ) 3 9H 2 O and other hydrated nitrates are used as raw materials, supplemented with hexamethylenetetramine, ethylene glycol, polyethylene glycol and other chemical reagents to make a solution, so that the dispersion and mixing of raw materials reaches the molecular level, and after standing and aging, the high temperature It is made by sintering, which has the advantages of high product purity, good homogeneity, and lower calcination temperature (200-300) ℃ than solid-phase sintering method, but has defects such as long preparation cycle, many synthesis steps, and complicated process.

The self-propagating combustion method is based on the sol-gel method, adding combustion agents such as citric acid monohydrate and urea, and using the rapid combustion of the combustion agent to increase the local temperature of the raw materials to reduce the overall calcination temperature. A promising synthetic method”, but its preparation cycle is still as long as several hours, and the combustion agent also affects the formation of sol and gel

Spark plasma sintering technology (Spark PlasmaSintering, referred to as SPS) is an emerging method in recent years, has been widely used in the manufacture of ceramics and metal materials, but has not been reported in the field of cement clinker and building materials

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