WO2015071518A1

WO2015071518A1 - Translucent glass-ceramic material comprising albite

Info

Publication number: WO2015071518A1
Application number: PCT/ES2014/070838
Authority: WO
Inventors: Juan Francisco Aparisi Ventura; Antonio José Ramos Clemen; Fidel Granel Cabedo; Manuel Sanz Pesudo
Original assignee: Esmalglass, Sau
Priority date: 2013-11-13
Filing date: 2014-11-12
Publication date: 2015-05-21
Also published as: ES2444740B2; ES2444740A1

Abstract

The invention relates to a translucent glass-ceramic material comprising albite as a main crystalline phase, and not containing lead, TiO2, As2O3, Sb2O3 or halides. The invention also relates to the method for producing the material, and to the use of said glass-ceramic material for coating materials, as well as for use in cooking surfaces and kitchen utensils and in structural elements.

Description

VITROCERAMIC MATERIAL TRANSFER ALBITA STRUCTURE

Field of the Invention

The present invention is generally framed in the field of crystalline materials and specifically refers to glass ceramic materials comprising albite as the predominant crystalline phase being translucent in the visible spectrum.

State of the art

Vitroceramic materials are microcrystalline materials obtained from a glass after heat treatment. The properties of said material are determined by the main microcrystalline phases and their final microstructures.

In general, the translucent glass ceramics obtained so far have a solid solution of β-quartz as the main crystalline phase, (W. Hoeland and G. Beall, in "Glass-ceramic technology", Am. Ceram. Soc, Westerville (2002), pages 88-96). These materials are generally obtained by heat treatment of a precursor glass (more conventionally a mixture of the constituents of said glass: a mineral filler, a precursor of said glass) whose composition is of the type Li0 ₂ - Al ₂ 0 _{3 -} Si0 ₂ ( THE). The heat treatment includes a nucleation stage followed by a crystal growth stage.

There are numerous patents referring to translucent glass-ceramic materials with β-quartz structure as the main crystalline phase, such as US patents US5,017,519, US6,750,167, JP 0696460.

So far, the few translucent glass ceramic that have been developed have a quartz structure, these materials have a considerable opacity, due to their composition they have rounded / molten edges and are not very stable. There is therefore a need to provide a ceramic hob that has a greater translucency that is stable with temperature, capable of presenting straight edges and that have a coefficient of expansion according to the intended use of said material. Description of the invention

Thus, in a first aspect, the present invention relates to translucent glass-ceramic material (hereinafter, glass-ceramic material of the present invention) which comprises albite as the main crystalline phase and does not contain lead, Ti0 ₂ , As ₂ 0 ₃ , Sb ₂ 0 _3i or halides.

In a more particular aspect the glass-ceramic material of the present invention comprises a composition in percentages by weight of the total composition referred to the oxides, of:

- Si0 ₂ : 52 - 58% by weight,

- At ₂ 0 ₃ : 20 - 28% by weight,

- CaO: 8 - 1 1% by weight,

- SrO: 8 - 1 1% by weight,

- K ₂ 0: 1 - 3% by weight,

- Na ₂ 0: 1 - 3% by weight,

- BaO: 0 - 1% by weight,

- Li ₂ 0: 0 - 1% by weight,

- MgO: 0-1% by weight,

- ZnO: 0 - 1% by weight,

- B ₂ 0 ₃ : 0 - 0.5% by weight,

- P ₂ 0 ₅ : 0 - 0.5% by weight

In a second aspect, the present invention relates to a process for obtaining the glass ceramic material (hereinafter, process of the present invention) of the present invention comprising the following steps: a) Cooling of the molten glass obtained in the step a) with water by quenching

b) grinding of the material obtained in step b) until a granulometry of less than 63 microns is achieved.

In a preferred embodiment, the glass ceramic material is processed in a mill for its breakage and to obtain material in granular form with a specific granulometry by sieving it. In another preferred embodiment, the material obtained is a ceramic enamel. For this, the material is ground together with specific additives and water in a ball mill until a specific rejection to obtain a ceramic enamel.

In another preferred embodiment, the glass ceramic material, in a first stage, is milled in a ball mill with specific additives and water until a determined rejection until a liquid suspension is achieved. After grinding a drying process of the suspension is carried out until a powder material is obtained with a specific rejection.

In another preferred embodiment, the glass-ceramic material, in a first stage, is milled in a ball mill with specific additives and binders and water until a specific rejection until a liquid suspension is achieved. In a second stage, the material is processed in two different ways:

Atomization of the liquid suspension until obtaining a spherical material with a specific granulometry.

Granulation of the liquid suspension until obtaining a spherical material of great hardness with a specific granulometry.

c) obtaining the translucent finish by heat treatment of the product obtained in step b)

More particularly, the fusion of the precursor vitreous material from step a) is carried out at a temperature between 1400-1500 ^e C.

More particularly, step c) is carried out for a maximum of 120 minutes at a temperature between 1 180-1220 ^e C.

In another aspect the present invention relates to the use of the glass ceramic material of the present invention for coating materials.

In another aspect the present invention relates to the use of the ceramic hob of the present invention on cooking surfaces and kitchen utensils.

In another aspect the present invention relates to the use of the glass ceramic material of the present invention in structural elements. Figures

Figure 1 shows the diffractogram obtained from sample 1.

Figure 2 shows the cross section of the sample 1 to the scanning electron microscope.

Figure 3 shows the global EDX analysis of sample 1

Figure 4 shows the cross section of the sample 1 to the scanning electron microscope with a resolution of 50 microns (a), with a resolution of 10 microns (b) and the EDX analysis of its main constituents (c, d and e).

Figure 5 shows the cross section of sample 2 under the scanning electron microscope.

Figure 6 shows the cross-section of the sample 2 to the scanning electron microscope with a resolution of 50 microns.

Figure 7 shows the cross section of sample 3 to the scanning electron microscope

Figure 8 shows the cross section of sample 3 to the scanning electron microscope with a resolution of 200 microns

Figure 9 shows the cross section of the sample 3 to the scanning electron microscope with a resolution of 10 microns

Figure 10 shows the overall EDX analysis of sample 3.

Figure 1 1 shows the cross section of the sample 3 to the scanning electron microscope with a resolution of 50 microns (e) and EDC analysis of its main constituents (a, b, c and d).

Figure 12 shows the cross section of sample 4 to the MEB with a resolution of 500 microns

Figure 13 shows the cross section of sample 4 to the MEB with a resolution of 200 microns

Figure 14 shows the overall EDX analysis of sample 4. Figure 15 shows the cross section of sample 4, with a resolution of 50 microns (e), with a resolution of 10 microns (f) and the EDX analysis of its main constituents (a, b, c and d).

Figure 16 shows the ceramic enamel prepared with the glass ceramic material of the present invention.

Figure 17 shows the granular material obtained with the glass ceramic material of the present invention.

Detailed description of the invention

Example 1: Procedure for preparing the glass ceramic material

Four samples were prepared by the following procedure: First, he prepared the mixture of the precursor composition containing:

- 54.8% by weight of Si0 ₂ ,

- 25% by weight of Al ₂ 0 ₃ ,

- 8.5% by weight of CaO,

- 8.5% by weight of SrO,

- 1, 1% by weight of K ₂ 0,

- 1, 1% by weight of Na ₂ 0,

- 0.8% by weight MgO,

- 0.2% by weight of ZnO

Once the precursor composition was formed, it was melted, for which the temperature was raised to 1400-1500 ^e C and then subjected to quenching with water. Once the material cooled, the material was cooled. grinding of the glass-ceramic material in a ball mill until obtaining a material in granular form with a granulometry of less than 63 microns. Then a stage of wetting the material with a water content of 5.5% and homogenization of the same was carried out to avoid the presence of lumps of greater granulometry. Then the cylindrical specimens were pressed at a pressure of 350kg / cm ² and dried for 1 hour in an oven at 1 10 ^e C. Finally It was subjected to a laboratory electric flask firing at different temperatures: 1 .180, 1 .200 and 1 .220 ^e C.

Through this procedure, 4 samples were obtained: sample 1, 2, 3 and 4.

Example 2: Microstructural characterization of the samples obtained in example 1 Next, microstructural characterization of the samples of glass ceramic material obtained in example 1 was carried out, which consisted in the quantification of crystalline phases by X-ray diffraction, as well as the Observation and analysis of the samples by scanning electron microscopy.

The identification of crystalline structures was performed by X-ray diffraction of the powder sample, using a BRUKER Theta-Theta model D8 Advance diffractometer. (figure 1) (ONLY 1 SAMPLE 1). (figure 22 of report C131220)

The following table shows the X-ray diffraction of sample 1.

Tube: Cu

Voltage: 30 kV

Intensity: 45 mA

Monochromator: no

Divergence slit: 0.6 mm

Time constant: 1, 2 s

Step size: 0.015 ^e

From 29 = 5 ^e to 29 = 90 ^e

Table 1: RY diffraction shows 1 to 1220 ^e C

The quantification of crystalline phases was carried out by means of a calibration curve with reference materials and the percentage of the crystalline phases was determined by comparison of the area of the majority peaks.

In sample 1 two phases were identified: - Ab: albite (NaAISi ₃ 0 _8): 18 ± 5%

- Si0 ₂ : Silicon dioxide: 4 ± 2%

Sample 1 presented a percentage of vitreous / amorphous phase of 78 ± 8%.

All samples were subjected to analysis by scanning electron microscopy. The micrographs and EDX analyzes performed are shown in Figures 2-6.

Figure 2 shows a photograph of the cross-section of the sample 1, in which the presence of closed porosity can be seen, as well as some darker particles whose appearance resembles infused, these areas seem to correspond to the crystalline phase of silicon dioxide determined by X-ray diffraction. Sample 1 is mainly composed of a crystalline phase embedded in a vitreous phase of very similar analysis. The analysis of the vitreous phase and the crystals is very similar, the main difference lies in the enrichment in aluminum and sodium and the potassium depletion of the crystalline phase. This phase could correspond to the albite phase identified by X-ray diffraction (figure 1), which also contains calcium that would correspond to the possible substitution.

Comparison between samples 2, 3 and 4

The micrographs and EDX analyzes performed are shown in Figures 1 -. As can be seen, these are very heterogeneous samples with the presence of a large amount of internal porosity, whose appearance varies depending on the sample. The three samples presented crystals but of different morphology, mainly of different sizes.

Figures 5 and 6 show the micrographs corresponding to sample 2, in this case the analyzes of the different phases were similar to those obtained for sample 1. Figure 6 clearly shows the areas where a quartz particle existed, which has generated a vitreous phase rich in silica that prevents the formation of the crystalline phase.

Figures 7 and 8 show the micrographs corresponding to sample 3. Figure 7 shows the presence of a large amount of porosity and very irregular, which indicates the greater refractoriness of this sample.

Figure 8 shows the tortuousness of the pores as well as the presence of particles of different types and of a large size. Figure 9 shows that the crystals are similar to those shown in sample 1. Also in Figure 1 1 It shows an area where you can see all the types of heterogeneities present. It shows the existence of alumina particles, quartz, vitreous phase areas without crystals and crystals richer in aluminum, sodium and calcium.

Figures 12 and 13 show the micrographs corresponding to sample 4, in this case, the porosity seems more rounded than in sample 3, this indicates its greater functionality. Figure 14 shows the overall analysis of the sample. A detail of the cross section of this sample is included in Figure 15, where it can be verified by analysis, the presence of alumina particles, quartz, vitreous areas and areas with crystals rich in aluminum, mainly. In this case, the comparison of the analyzes of the crystalline vitreous phase are not very different, the main difference is in the lower aluminum content and higher potassium content of the vitreous phase. In addition, the morphology of the crystals seems different from that observed in the two previous samples, they are larger crystals and appear to be in greater proportion.

Example 3: Coatings with the glass ceramic material of the invention

The glass ceramic material was applied as a ceramic glaze on cake of different technologies and after a cooking stage, a high gloss ceramic finish with high Mohs hardness was achieved. As shown in Figure 16, the ceramic coating obtained had a high gloss and high scratch resistance.

The vitroceramic material of the invention after a cooking process and subsequent lapping / polishing, gave rise to a granular material that as shown in Figure 17 had a high gloss surface (greater than 91 ^e ) with high Mohs hardness and high scratch resistance .

The glass ceramic material of the present invention was used both as a ceramic coating and a glass ceramic panel for structural and concine use.

Claims

one . Translucent glass - ceramic material characterized by comprising albite as main crystalline phase and contains no lead, Ti0 _2, As ₂ 0 _3, Sb ₂ 0 _3, or halides.

2. Vitroceramic material according to claim 1, characterized in that it comprises a composition in percentages by weight of the total composition referred to the oxides, of:

- Si0 ₂ : 52 - 58

- At ₂ 0 ₃ : 20 - 24

- CaO: 8 - 1 1

- SrO: 8 - 1 1

- K ₂ 0: 1 - 3

- Na ₂ 0: 1 - 3

- BaO: 0 - 1

- Li ₂ 0: 0 - 1

- MgO: 0 - 1

- ZnO: 0 - 1

- B ₂ 0 ₃ : 0 - 0.5

- P ₂ 0 ₅ : 0 - 0.5

3. Method for obtaining the translucent glass ceramic material according to any of claims 1-2, characterized in that it comprises the following steps:

a) Fusion of the precursor vitreous material comprising a composition in percentages by weight of the total composition referred to the oxides of Si0 ₂ : 52-58, Al ₂ 0 ₃ : 20-28, CaO: 8-1 1, SrO: 8 - 1 1, K ₂ 0: 1 - 3, Na ₂ 0: 1 - 3, BaO: 0 - 1, Li ₂ 0: 0 - 1, MgO: 0 - 1, ZnO: 0 - 1, B ₂ 0 ₃ : 0 - 0.5, P ₂ 0 ₅ : 0 - 0.5;

b) Cooling of the molten glass obtained in step a) with water by quenching

c) grinding of the material obtained in step b) until a granulometry of less than 63 microns is achieved.

d) obtaining the translucent finish by heat treatment of the product obtained in step c)

4. Method according to claim 3 characterized in that the fusion of the precursor vitreous material from step a) is carried out at a temperature between 1400- 1500 ^e C.

5. Method according to any of claims 3-4, characterized in that the heat treatment of step d) is carried out at a temperature between 1 180-1220 ^e C and maximum 120 minutes.

6. Use of the glass ceramic material according to any of claims 1-2 for the coating of materials.

7. Use of the ceramic hob according to any of claims 1-2 on cooking surfaces and cooking utensils.

8. Use of the glass ceramic material according to any of claims 1-2 in structural elements.