RU2142437C1 - Charge material for manufacturing glass ceramics - Google Patents

Abstract

FIELD: ceramics. SUBSTANCE: invention relates to corundum-based glass ceramics and can be used for manufacturing environmental safe construction parts employed in mechanical engineering, food industry, and construction. Charge material contains 30-60% wastes coming from processing of 24

Description

 The invention relates to the technology of ceramic materials, in particular to corundum-based glass ceramics, and can be used in the manufacture of environmentally friendly structural products with high crack resistance used in the engineering, food, and construction industries.

Known ceramic material (1), for the preparation of which a charge is used, which includes in wt.% The following components: 10-30 aluminum oxide and 70-90 glass. In this case, glass wastes containing manganese oxide are used in the following ratio of components, wt.%:
SiO ₂ - 65-68
Al ₂ O ₃ - 0.8-1.2
CaO - 6.1-6.5
MgO - 4.2-5.1
BaO - 1.3-1.5
Na ₂ O - 16.2-16.7
K ₂ O - 1.1-1.3
Fe ₂ O ₃ - 0.8-1.1
Mn ₂ O ₃ - 1.5-1.6
The disadvantages of the above technical solutions are the narrow range of application of this material, the need to use special glass containing manganese oxide and expensive aluminum oxide.

The closest in technical level and the achieved result is a mixture comprising 40-60 wt.% Corundum and 40-60% aluminosilicate glass with the following ingredients, wt.%: SiO ₂ 46.2-55.2; Al ₂ O ₃ 30.0-41.4; MgO 12.4-14.8 and designed to produce ceramics used in the refractory, electronic and engineering industries (2).

The disadvantage of this composition of the charge material is the need for special manufacture of aluminosilicate glass, granulation and further high-temperature (1450-1550 ^o C) sintering of billets to obtain dense ceramics, which requires the use of special energy-intensive and difficult to handle equipment, as well as low crack resistance of the ceramic material. In addition, the manufacture of this charge requires a significant amount of expensive corundum.

 The task of the invention is to develop an environmentally friendly composition of the charge material to obtain glass ceramics with high crack resistance from affordable and cheap raw materials.

 The technical result is an increase in crack resistance of glass ceramics.

The specified technical result is achieved in that the charge material for the manufacture of glass ceramics contains 30-60% of waste from the processing of alundum abrasive wheels of type 24 A on a ceramic bond (hereinafter referred to as corundum component or simply corundum) and 40-70% of glass, which is glass powder, obtained by grinding the battle of food packaging glasses or glass waste of the following composition, wt. %: SiO ₂ 67-73; Al ₂ O ₃ 3.2-10; CaO 6.5-6.9; MgO 4.3-5.1: R ₂ O (Na ₂ O + K ₂ O) 14-14.3; Fe ₂ O ₃ 0.1-1.5.

The use of waste from processing abrasive alundum circles on a ceramic bond as corundum provides a dense glass-ceramic material due to the improvement of interparticle bonds in the composite during high-temperature sintering, which is due to the finished binder contained in the waste, which has good wettability with respect to corundum grains and particles close in composition used glass powder. The use of bottled glass and other types of container glass or similar chemical waste products in the form of glass additives will help ensure the stability of glass ceramics to various chemical and mechanical influences due to the significant content of Al ₂ O, MgO and CaO oxides. In addition, the use of the proposed components for the manufacture of the charge material can reduce the cost of glass-ceramic products and improve the environmental situation.

 The proposed glass-ceramic material is prepared as follows.

The starting materials (cullet and waste from the processing of alundum circles) are preliminarily crushed in a vibrocentrifugal mill. The crushed components are mixed in a certain percentage in a vibratory mill with alundum balls for 30 minutes with the addition of 5% aqueous solution of polyvinyl alcohol (PVA) in an amount of 5 wt.% In terms of dry matter. The resulting mixture is rubbed through a sieve N 025 and pressed with a pressure of 1.5-2 t / cm ² . The compacts are calcined in an air atmosphere at a rate of temperature rise of 600 ^° C / h with holding for 2 hours at 400 ^° C and 1 hour at 750 ^° C, then they are cooled together with the furnace.

A two-hour exposure at a temperature of 400 ^o C is necessary for the burning out of plasticizing binder (PVA) from sintered billets.

The sintering temperature T = 750 ^o C provides a dense glass-ceramic material p = 2.50-2.77 g / cm ³ , hardness HRA 50-84 and crack resistance according to the parameter K _1C = 7.8-18.0 MPa • m ^{1 / 2} depending on the composition of the composite. The structure of the material is pronounced heterogeneous - corundum particles are evenly distributed in the glass matrix.

 The proposed technical solution is illustrated by examples.

Example 1: Take the battle of bottle glass, the chemical composition of which is shown in table 1, crushed in a vibrocentrifugal mill to obtain a powder with S _beats. = 6500 cm ² / g. As the corundum component, we used waste from processing alundum abrasive wheels of type 24 A PP 40x32x10 25 C M on a ceramic bond, the chemical composition of which is shown in Table 2. Waste from processing abrasive wheels was also subjected to preliminary grinding in a vibrocentrifugal mill to obtain powder with S _beats. = 3500 cm ² / g. The resulting powders are mixed in a certain percentage when adding 5% aqueous solution of PVA in an amount of 5 wt.% In terms of dry matter. The resulting mixture is wiped through a No. 025 sieve and pressed by cold pressing on a hydraulic press with a pressure of 1.5 t / cm ² . Next, the obtained compacts are subjected to sintering according to the regime: 400 ^o C - 2 hours +750 ^o C - 1 hour. The sintering temperature of the workpieces 750 ^o C is optimal (see table 3), because this achieves the maximum value of the density and coefficient of crack resistance. The volumetric shrinkage of the material in this case is not more than 20%. Sintered products retain their geometric shape well. An increase in the sintering temperature leads to a certain decrease in the indicated characteristics (see tab. 3).

 An increase in the composition of the charge material of the corundum component leads to an increase in the density of the resulting glass ceramics (see table. 3). The crack resistance of ceramics increases with an increase in corundum content to 50%, then decreases from 60% (see table 3).

 The hardness of the glass ceramics obtained from the proposed charge material is HRA 50-84.

 The optimal is the composition of the charge material corresponding to the content of the components in the following wt.%: 50 corundum and 50 glass.

Glass ceramics made of this charge material have the highest crack resistance (18.0 MPa • m ^1/2 ) and hardness (84 HRA).

 Example 2. As a glass additive, a container glass break is used, the chemical composition of which is shown in table 4. The corundum component was used the same as in example 1.

Glass ceramics were made from a charge material containing from 40 to 70 wt.% Glass and 30-60 wt.% Corundum component. In this case, the crack resistance of ceramics according to the parameter K _1C was 17.8 MPa • m ^1/2 , the hardness HRA 82 units.

 The proposed composition of the charge material for the manufacture of glass ceramics with high crack resistance was first implemented by the authors, has a scientific novelty and is, according to the authors, the basis for issuing a certificate for the invention.

 For the claimed invention in the form as described in the claims, the possibility of its implementation using the above-described technological methods, conditions and modes of its implementation is confirmed.

 The composition of the charge material for the manufacture of glass ceramics, proposed in this invention during its implementation, ensures the implementation of the claimed technological result. Therefore, the claimed invention meets the requirement of "industrial applicability".

References
1. A.S. USSR N 1599347, class C 04 B 35/10.

 2. A.S. USSR N 1571035, class C 04 B 35/10. Bull. N 22, 1990

Claims (1)

Charge material for the manufacture of glass ceramics based on corundum and glass, characterized in that the corundum component uses waste from the processing of alundum abrasive wheels of type 24A on a ceramic bond, the glass is a glass powder obtained by grinding a battle of food packaging glasses or glass waste, of the following composition, wt .%:
SiO ₂ - 67 - 73
Al ₂ O ₃ - 3.2 - 10
CaO - 6.5 - 6.9
MgO - 4.3 - 5.1
R ₂ O (Na ₂ O + K ₂ O) - 14 - 14.3
Fe ₂ O ₃ - 0.1 - 1.5
and the charge material contains components in the following ratio, wt.%:
Waste from processing alundum abrasive wheels - 30 - 60
Glass - 40 - 70

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