RU2465244C1 - Method of producing slip for casting ceramic articles - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of ceramic slip used in production of ceramic articles. The method of producing slip for casting ceramic articles by wet-grinding, in a bead mill, aggregates and flux agents and adding complex additives containing sodium tripolyphosphate, superplasticiser SB-FF and sodium hydroxide, with the following ratio of components, in wt %: superplasticiser SB-FF - 16; sodium tripolyphosphate - 60; sodium hydroxide - 24.

EFFECT: reduced moisture content of the slip while preserving its mobility and higher strength of articles.

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Description

The invention relates to the field of preparation of ceramic slurry used in the manufacture of ceramic products by casting. One of the most important tasks in the technology for the preparation of casting ceramic slurry is to ensure sufficient mobility of the slurry with its minimum humidity. This is achieved by introducing various diluent additives.

The prior art known fluidizing additive for refractory ceramic systems according to the patent of Russian Federation No. 2238921 "Complex fluidizing organomineral additive for refractory molding systems and a method of manufacturing materials using it." Known additive consists of sodium tripolyphosphate and plasticizer SB-5 in the following ratio of the components of the additive, wt.%

plasticizer SB-5 twenty sodium tripolyphosphate 80

A disadvantage of the analogue is the lack of thinning effectiveness.

As a prototype, a slip for the production of sanitary-ceramic products containing a complex fluidizing additive (Zdorenko N.M. “Rheotechnological properties of kaolinite and kaolinite-hydaceous clay masses with a complex organomineral additive”) is accepted: thesis candidate of technical sciences: 02.00.11 / N. M. Zdorenko. - Belgorod: BSTU named after V.G. Shukhov. - 2009. - 140 p.), Consisting of sodium tripolyphosphate and Belgorodsky superplasticizer based on phloroglucin and furfural (SB-FF) in the following ratio of additive components, wt. %

plasticizer SB-FF twenty sodium tripolyphosphate 80

The disadvantage of the prototype is the use of a rather expensive additive, which does not provide sufficient mobility of the slip while reducing its moisture and insufficient strength of the finished product.

The technical result of the invention is to obtain a cheaper ceramic slip with less moisture while maintaining its mobility and increasing the strength of the finished product.

The technical result is achieved due to the fact that the method for producing a slip for casting ceramic products includes wet grinding in a ball mill of clay materials that are thinner and smoother with the introduction of a complex additive containing sodium tripolyphosphate and superplasticizer, and SB-FF superplasticizer is used as a superplasticizer and in addition, sodium hydroxide is additionally added to the complex additive in the following ratio of components, wt.%:

superplasticizer SB-FF 16 sodium tripolyphosphate 60 sodium hydroxide 24

Synthesize SB-FF in the following way: an aqueous solution is prepared from phloroglucin in the presence of NaOH, heating it to 50 ° C and mixing until complete dissolution. Then furfural is added and heated to 70 ° C. As a result of polycondensation of phloroglucinol with furfural, a 20% SB-FF solution is formed, which can be used both in the form of a solution and in the form of a dry powder (after evaporation and grinding). SB-FF belongs to the 4th class of toxicity (low hazard substances).

Sodium tripolyphosphate and sodium hydroxide are widely used in the ceramic and refractory industries. However, the introduction of sodium tripolyphosphate or sodium hydroxide into the ceramic slip as individual additives, as well as the introduction of SB-FF, does not lead to such an effective thinning of the slip as the introduction of a complex containing sodium tripolyphosphate, sodium hydroxide, and SB-FF.

The proposed method differs from the prototype in that the slip for casting ceramic products includes superplasticizer SB-FF and sodium hydroxide in the following ratio, wt.%:

superplasticizer SB-FF 16 sodium tripolyphosphate 60 sodium hydroxide 24

The introduction of cheap sodium hydroxide into the slip composition, which increased its Ph, made it possible to reduce the amount of more expensive superplasticizer and sodium tripolyphosphate, without changing the slip rheological parameters, and to improve the quality of the finished product.

For experimental verification of the effectiveness of this additive, a ceramic slip was prepared, which is used for the production of sanitary-ceramic products. Its components are: clay materials 53 wt.%; lean 32 wt.%; meltwater 15 wt.%.

A well-known complex additive was added to the slip, containing 0.02 wt.% SB-FF and 0.08 wt.% Sodium tripolyphosphate (composition 1), and a new complex additive containing 0.016 wt.% SB-FF, 0.024 wt.% Hydroxide sodium and 0.06 wt.% sodium tripolyphosphate (composition 2).

The slurry was prepared by wet grinding in a ball mill. The mobility of the slurry with a moisture content W _SL = 32% was evaluated by a flow time of 100 ml of the slurry after standing it alone for 30 seconds (first flow) and 30 minutes (second flow). The thixotropy coefficient K was also determined (Table 1).

Prototypes were cast from the slip and fired at a maximum firing temperature of 1200 ° C (Table 2).

Table 1 Slurry rheological parameters Slurry Composition First fluidity, s Second fluidity, s TO The rate of weight gain, g / cm ² · min 1 (prototype) 16,0 19.0 1,2 0,090 2 13.0 15,5 1,2 0,091

As can be seen from table 1, the slip containing the developed complex additive, in comparison with the slip prototype, has greater mobility, which reduces its moisture content while maintaining the rheological parameters. Studies have shown that the developed additive makes it possible to reduce humidity from 32 to 29% for equally-moving slips. This increases the rate of mass gain up to 0.11 g / cm ² · min, which has a positive effect on the process.

table 2 Physico-chemical properties of products after firing Options Slurry Composition 1 (prototype) 2 The apparent density, kg / m ³ 2110 2180 Relative density, % 81.2 84.0 Open porosity,% 1.9 1,5 Closed porosity,% 18.1 15.3 Water absorption,% 0.9 0.69 Compressive strength, MPa 74.0 89.3

The increase in the density of samples obtained from a slip containing the claimed complex additive (Table 2) is due to a denser packing of particles, which is the result of an increase in the content of the dispersed phase in the slip. A denser homogeneous structure of the samples favorably affects the sintering process, as a result of which the porosity decreases and the strength of the finished products increases, which significantly reduces product rejection at all stages of the technological process.

From the above example it can be seen that the inventive method allows to obtain a cheap ceramic slip with less moisture while maintaining its mobility and increasing the strength of the finished product. Thus, the claimed technical result is achieved.

Claims (1)

A method of producing a slip for casting ceramic products by wet grinding clay materials, thinner and smoother in a ball mill, and introducing into them a complex additive containing sodium tripolyphosphate and a superplasticizer, characterized in that the superplasticizer SB-FF is used as well as a complex additive sodium hydroxide is additionally introduced in the following ratio of components, wt.%:
superplasticizer SB-FF 16 sodium tripolyphosphate 60 sodium hydroxide 24