WO2022271124A1

WO2022271124A1 - A novel vitrified ceramic product

Info

Publication number: WO2022271124A1
Application number: PCT/TR2022/050491
Authority: WO
Inventors: Hasibe Aygul YEPREM; Sevil YUCEL; Murat DOGDU
Original assignee: Yildiz Teknik Universitesi
Priority date: 2021-06-21
Filing date: 2022-05-26
Publication date: 2022-12-29

Abstract

The invention relates to a vitrified ceramic product with reduced weight and the ability to thicken fast without any change in its strength values for use in ceramic sanitary ware. Accordingly, vitrified ceramic products contain raw materials including quartz, clay group, feldspar, carbonate and grinders and silica aerogel in certain proportions by weight.

Description

A NOVEL VITRIFIED CERAMIC PRODUCT

TECHNICAL FIELD

The invention relates to a vitrified ceramic product with reduced weight and the ability to thicken fast without any change in its strength values for use in ceramic sanitary ware.

PRIOR ART

Ceramic sanitary ware, or plumbing ceramics, is a branch of the industrial ceramic industry and is the name given to vitrified ceramic products such as sinks, feet, toilets, reservoirs, toilet stones, bidets and urinals, which are generally used in bathrooms and toilets. The said vitrified ceramic products are obtained as a result of shaping the masses consisting of clay, kaolin, feldspar and quartz type inorganic raw materials by various methods, glazing and baking around 1200-1250°C.

Vitrified ceramic products are shaped by casting and are obtained from casting sludge using various components and raw materials that perfect the casting process.

The liter weight of the casting sludge in the art is generally 1780 grams or more. The fact that ceramic products are so heavy creates negativities for occupational health and safety. In addition, due to the high weight of ceramic products, they can be transported in small numbers in unit time, increase fuel consumption during baking and cause high costs for companies.

A good casting sludge in the art is expected to thicken by at least 7.5 mm per hour and its thixotropy is expected to be between 25-35% according to Gallenkamp viscometer measurements. While it becomes difficult to thicken in casting sludges with lower thixotropy, deformations occur for products with thin wall thickness. Therefore, it is preferred that the thickness values are at certain values for vitrified products.

The production of vitrification products in large sizes and desired sizes is another problem faced by manufacturers. Large-scale ceramic sanitary ware poses risks such as shrinkage and deformation of products, cracks and fractures in the production phase. There are limited studies in the technical field to reduce these risks for the smooth production of vitrified products.

All the problems mentioned above have made it necessary to make an innovation in the relevant technical field as a result.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a novel vitrified ceramic product in order to eliminate the above-mentioned disadvantages and to bring new advantages to the related technical field.

It is an object of the invention to provide a vitrified ceramic product with reduced weight without any change in strength values.

It is an object of the invention to provide a vitrified ceramic product that can thicken faster.

The invention relates to a vitrified ceramic product that contains silica aerogel compounds as a component, has a reduced weight and has the ability to thicken fast. In a possible embodiment of the invention, the vitrified product contains the said silica aerogel component in an amount between 0.5% and 10% by weight. In a preferred embodiment, the product contains a silica aerogel component in an amount between 1% and 7.5% by weight. In the preferred basic embodiment, the product contains a silica aerogel component in an amount between 2% and 5% by weight.

The three-point bending test result of the vitrified ceramic product of the invention is at least 24 MPa.

In a possible embodiment of the invention, the vitrified product contains fireclay in an amount between 25-30% by weight, quartz in an amount between 10-15% by weight, k-feldspar in an amount between 1-3% by weight, wollastonite in an amount between 3-4% by weight, kaolinite in an amount between 15-20% by weight, clay in an amount between 30-35% by weight, silica aerogel components in an amount between 0.5-10% by weight.

The invention also relates to the production of a vitrified ceramic product. The said production method includes the following process steps: obtaining silica aerogels from glass water by sol-gel method, ii. mixing the obtained silica aerogels with other raw materials such as clay, kaolinite, feldspar, fireclay, water and obtaining FFC sludge, iii. homogenizing by mixing FFC sludges and separation of particles such as iron and carbon, followed by aging, iv. pouring it into the gypsum mold after the completion of the process step (iii) for obtaining vitrified ceramic products in different designs and performing drying processes, v. performing sintering processes.

A possible embodiment of the invention is that the said silica aerogel is added to the FFC sludge, to the vitrified ceramic product in an amount between 0.5% and 10% by weight in the process step (ii).

A possible embodiment of the invention is that the silica aerogel is added to the FFC sludge in an amount between 1% and 7.5% by weight in the process step (ii).

A possible embodiment of the invention is that the silica aerogel is added to the FFC sludge in an amount between 2% and 5% by weight in the process step (ii).

A possible embodiment of the invention is that the aging process in the process step (iii) takes at least 2 days.

A possible embodiment of the invention is that the drying process in the process step (iv) takes at least 24 hours.

A possible embodiment of the invention is that the sintering process step in the process step (v) is carried out by the following process steps;

• increasing the temperature from 40°C to 800°C by 160°C/hour

• increasing the temperature from 800°C to 1250°C by 180°C/hour

• performing uncontrolled cooling between 1250°C and 40°C.

DETAILED DESCRIPTION OF THE INVENTION

The subject of the invention in this detailed description is related to the vitrified ceramic product with reduced weight and the ability to thicken fast without any change in its strength values for use in ceramic sanitary ware; it is explained with examples that do not have any limiting effect only for a better understanding of the subject.

The invention is mainly related to the field of ceramic health products and here, as a health ceramic product, commercial products such as sinks, sink feet, toilets, reservoirs, bidets, urinals, closets, kitchen sinks, bathtubs, shower trays in different designs or sizes are meant.

“Viscosity” is a common feature of liquids and gasses and is known as the ability to flow.

In the invention, the term “thixotropy” is defined as the fluid sludge losing its fluidity and coagulating when it is still and returning to its original state when mixed.

The resistance of liquids to flow is called “viscosity”.

The vitrified ceramic product of the invention is obtained by the methods known in the art and firstly, casting sludge with certain weight ratios is prepared for this. The subject of the invention is essentially not obtaining the casting sludge with a new recipe; it is the addition of a new component to the existing casting sludge.

In the invention, casting sludge Fine Fire Clay (to be referred to as FFC) components are used which is widely used in the art for obtaining a vitrified ceramic product. The components mentioned herein are compounds of clay, quartz, kaolin, feldspar, fireclay, and wollastonite.

Unlike the existing applications, silica aerogels are added to the FFC sludge recipe. While quartz-like silica compounds are the main component of the FFC recipe in the current applications, silica-based compounds are used instead of these components in the subject of the invention. The FCC sludge of the invention contains silica aerogel compounds that are both lighter than the silica-based compounds they replace, and provide superior properties for vitrified products during obtaining the product.

Instead of the quartz in the Fine Fire Clay (FFC) sludge recipe, to the subject of the invention, silica aerogel, which is silica with a lower weight is added in certain ratios and the ratios of other raw materials clay, kaolin, feldspar, fireclay, wollastonite are adjusted. The subject of the invention is not related to other raw materials used according to the vitrification products in the art. Therefore, the subject of the invention is not limited to other raw materials that vary according to the types of vitrified ceramic products. The invention mainly proposes the use of silica aerogels instead of silica-based quartz or similar compounds previously used in the FFC recipe and refers to appropriate arrangements.

The invention relates to the addition of silica aerogels in certain weight ratios to the FFC recipe containing clay group raw materials, feldspar, carbonate-containing raw materials and grinding medium raw materials. The silica aerogel mentioned herein is added to the FFC recipe as a component in an amount between 0.5% and 10%. In a preferred embodiment, the silica aerogel is added to the FFC recipe as a component in an amount between 1% and 7.5%. In another preferred embodiment, the silica aerogel is added to the FFC recipe as a component in an amount between 2% and 5%. In a preferred embodiment, the silica aerogel is added to the FFC recipe as a component in an amount between 0.5% and 3%.

The production of silica aerogel to be used as a component in the invention is carried out by the sol-gel method, which is the most applied method in the art. Flere, the silica aerogel can also be obtained by applying other production methods known in the art. The scope of protection of the invention is not limited to the production of silica aerogel.

In the invention, in addition to the production of sol-gel, solvent exchange and surface modification methods are used to protect the pores of silica aerogels and to have a high surface area.

The drying process, which is the most critical process step in the sol-gel production method for the production of silica aerogels in the invention, is carried out at gradual temperatures in a vacuum oven. It is ensured that silica aerogels with high volumes of pores are obtained by removing the solvent lastly from the silica aerogels to be obtained in this way.

In the invention, instead of silica raw materials such as TEOS or TMOS, glass water, tradename of which is sodium silicate solution, is used as the initiator for more affordable silica aerogel production costs. In order to provide gelling, hydrochloric acid (37%) is prepared as 6 M and 1 M and high-grade ethanol and n-heptane are used for solvent change and surface modification.

BET method and Specific Surface Area and Pore Distribution Measurement Device, Fie Pycnometer, tap density, SEM, FTIR and ICP-OES devices and method analysis were performed for the characterization of silica aerogels to be included in the invention regarding their physical and chemical structure. Table 1 shows the value that characterizes the characteristics of silica aerogels with the mentioned test and analysis methods.

Table 1. Some Characteristic Values of Silica Aerogels

1. Vitrified Ceramic Production

In order to obtain vitrified ceramic products, it is necessary to prepare FFC sludge first, as mentioned before. The sludge recipe is determined for FFC sludge.

In order for the FFC sludge to be homogeneous as desired, it is ensured that the raw materials to be added are between certain grain sizes. Grain reduction processes are carried out by grinding and other similar grain reduction processes.

Silica aerogel may have been purchased or obtained through production methods as previously mentioned. In order to obtain FFC sludge, firstly the silica aerogel is mixed with water and mixed with raw materials previously brought to appropriate grain sizes. Compositions of FCC sludge obtained are given in Table 2 in detail. During the mixing process, sodium silicate is added to maintain the fluidity of FFC sludge at certain values. After the end of this process, the suitability tests of the FFC sludge obtained for the production of vitrified ceramic products are carried out. These are density determination, thixotropy, liter weight, temperature tests or measurements. The characteristics of the FCC sludges obtained are given in Table 3. From the FFC sludge, which is accepted as suitable, particles such as carbon are then removed with a 300-micron griddle and then the iron in the sludge is removed with a magnetic stirrer. After these stages, FFC sludge is put to rest, and aging process is performed for at least 2 days. After the aging process, FFC sludge is mixed and dissolved again, prototype casting is performed in the gypsum mold, and it is removed from the gypsum mold after 2 to 6 hours.

Table 2. Chemical Composition of Silica Aerogel Containing FCC Sludge

Table 3. Characteristic Values of FFC Sludge Used in the Manufacture of Vitrified Ceramic

Products

1.1 Application of Drying and Sintering Processes Samples poured into the molds in the specified designs are removed from the gypsum mold after a period of 2 to 6 hours. The samples removed from the molds are then dried and sintered. Drying processes are carried out at room temperature for at least 24 hours.

Sintering is performed on the samples that are dried. The sintering processes in question are carried out according to TSE EN 997+A1 standards by following the process steps given below;

• Increasing the temperature from 40°C to 800°C, 160°C/hour

• Increasing the temperature from 800°C to 1250°C, 180°C/hour • Uncontrolled cooling between 1250°C and 40°C

Sintered samples, can be used as vitrified ceramic products after design processes. However, a number of test methods are applied to the samples to determine their suitability for use as a vitrified ceramic product and their characteristics are analyzed.

2. Characterization of Vitrified Ceramic Products

With the completion of the sintering processes, the samples ready to be used as vitrified ceramic products are expected to remain between some characteristic values. For this reason, a number of test and analysis methods are applied to the samples.

In the studies conducted, the products obtained by using the existing techniques and raw materials are evaluated as the reference product (the chemical composition is given in Table 4), while the other 5 trial products are evaluated as products that are produced with the production methods where all conditions are the same with the reference product, and where not only the quartz component in the reference product but also the silica aerogels are included as components.

Table 4. Chemical Composition of the Reference Product used in the Tests

All samples tested are obtained in the same production method and conditions. Accordingly, a reference product is defined as a product known in the art, sample 1 as a product containing 0.55% by weight of silica aerogel component, sample 2 as a product containing 3% by weight of silica aerogel component, sample 3 as a product containing 5% by weight of silica aerogel component, sample 4 as a product containing 7.5% by weight of silica aerogel component and sample 5 as a product containing 10% by weight of silica aerogel component. All test results are given in Table 3.

2.1 Thickening

After the casting sludge was removed from the mold, it was examined by measuring its thickening with a digital caliper in wet, dry, and baked conditions. As a result of the study conducted after determining the average thickness by taking at least 4 measurements, it was observed that the thickness that can be gained in 1 hour increased as the amount of silica aerogel increased. This showed that the desired thickness could be obtained in a shorter time.

2.2 Water Absorption Test

Water absorption tests have been carried out according to TSE EN 997+A1 standards. According to these standards, the dry weights (G1) of the samples were measured first. Then, the samples were boiled in distilled water for 2 hours and after the boiling process was finished, the samples were kept in water for 20 hours. After the process was completed, the surface of the samples was dried and their weights (G2) were remeasured with an electronic scale.

The formulation showing the calculations made is shared below.

(G2-G1)

Water Absorption % = - x100

(G1)

2.3 Shrinkage Tests

The sludge was generally poured into the gypsum mold to obtain plates of 10x50x100 mm. While these plates were still wet, measurements were made by the caliper (L1). The plates were then dried in the drying cabinet at 105°C and the dry length values were remeasured with a caliper (L2). After the samples were dried, they were sintered at 1250°C and their length values were measured with the help of a caliper (L3). For shrinkage tests, calculations were made on at least 3 samples in each step. Detailed information about the shrinkage analysis is shown in Table 5. Accordingly, it was observed that as the amount of silica aerogel in the recipe increased, the drying, total and baking shrinkage increased. If the shrinkage values are seen above the standards, it is due to aerogel. The different thixotropes and liter weights of the recipes in the studies support the deviation in shrinkage. It does not pose a problem for the product.

General comment, due to the high water absorption of silica aerogel, it attracts more water as its amount in the recipe increases. Afterwards, shrinkage is high as it will lose this water in drying.

Table 5. Shrinkage Analysis Results of the Obtained Samples

2.4 Strength Test A strength test was performed with a 3-point bending method. The distance between the supports has been determined as 150 mm according to TSE EN 997+A1 standards. The samples were centered on the supports and the upper claw of the device was in close contact with the sample and a bending process was provided. The load continued to be applied until the sample was broken. Measurement was performed with 10 samples for each recipe and the average was taken as a basis. According to the standard, the samples are expected to show strength above 24 MPa. In the strength tests carried out, this result was obtained in 5 recipes and 30.44 MPa strength was determined in the sample containing the lowest 10% silica aerogel. Results are shared in Table 6.

Table 6. Characterization Values of Vitrified Ceramic Products according to Silica Aerogel content 2.5 XRD (X-Ray Diffraction Method)

In order to examine the crystal phase structure of baked samples, 5 measurements were made for each sample in the XRD device. The phases that emerge in the structure as a result of the measurements are given in Table 7.

Table 7. Determination of Phases of Samples in XRD device

It is obvious that the products in which silica aerogels are used as a component in the production of vitrified ceramic products subject to the invention will be considered as products with high added value for the related technical field. The weight problem, which is the biggest disadvantage of vitrified ceramic products in the present art, has been reduced by up to 28.3% in the vitrified ceramic product obtained in the present invention. A decrease in this value provides an advantage in many areas from fuel efficiency to transportation during the production of products. The silica aerogel used in the invention is not obtained from silica precursors such as TEOS, but from sodium silicate glass water, so it will be less costly than the existing silica aerogel productions. The vitrified ceramic product obtained in the invention thickens faster in unit time than the vitrified ceramic products obtained with the current techniques. In this way, it is possible to obtain more vitrified ceramic products with unit time, energy or fuel. It is obvious that the production costs of vitrified ceramic products obtained in this way will be lower. In the studies carried out, Fine Fire Clay (FFC) sludge recipes containing 0.55%, 3%, 5%, 7.5% and 10% silica aerogel by weight were prepared. At the end of the prepared recipes, it was determined that the sample containing 10% silica aerogel was 28.3% lighter than the reference sample. As a result of the studies, the strength of the product is above 24 MPa, as requested according to the standard and its suitability for use has been determined. In addition, it has been observed that this developed product thickens faster and reaches the desired thickness in a shorter time.

The scope of protection of the invention is specified in the attached claims and cannot be limited to those explained for sampling purposes in this detailed description. It is evident that a person skilled in the art may exhibit similar embodiments in light of the above-mentioned facts without drifting apart from the main theme of the invention.

Claims

1. The invention is a vitrified ceramic product that contains silica aerogel compounds as a component, has a reduced weight and has the ability to thicken fast.

2. A product according to claim 1 , characterized in that it contains said silica aerogel component in an amount between 0.5% to 10% by weight.

3. A product according to claim 2, characterized in that it contains a silica aerogel component in an amount between 1% and 7.5% by weight.

4. A product according to claim 2 or 3, characterized in that it contains a silica aerogel component in an amount between 2% and 5% by weight.

5. A product according to any of claims 1-4, characterized in that the three-point bending test result is at least 24 MPa.

6. The product of one of claims 1 -5 characterized in that it contains fireclay in an amount between 25-30% by weight, quartz in an amount between 10-15% by weight, k- feldspar in an amount between 1-3% by weight, wollastonite in an amount between 3- 4% by weight, kaolinite in an amount between 15-20% by weight, clay in an amount between 30-35% by weight, silica aerogel components in an amount between 0.5- 10% by weight.

7. A production of the product according to any one of claims 1-6, characterized in that it contains the following steps: i. obtaining silica aerogels from glass water by sol-gel method, ii. mixing the obtained silica aerogels with other raw materials such as clay, kaolinite, feldspar, fireclay, water and obtaining FFC sludge, iii. homogenizing by mixing FFC sludges and separation of particles such as iron and carbon, followed by aging, iv. pouring it into the gypsum mold after the completion of the process step (iii) for obtaining vitrified ceramic products in different designs and performing drying processes, v. performing sintering processes.

8. A production according to claim 7, characterized in that the said silica aerogel is added to the FFC sludge in an amount between 0.5% and 10% by weight in the process step (ii).

9. A production according to claim 7, characterized in that the silica aerogel is added to the FFC sludge in an amount between 1% and 7.5% by weight in the process step (ii).

10. A production according to claim 7, characterized in that the silica aerogel is added to the FFC sludge in an amount between 2% and 5% by weight in the process step (ii).

11. A production according to claim 7, characterized in that the aging process in the process step (iii) takes at least 2 days.

12. A production according to claim 7, characterized in that the drying process in the process step (iv) takes at least 24 hours.

13. A production according to claim 7, characterized in that the sintering process step in the process step (v) is carried out by the following process steps;

• increasing the temperature from 40°C to 800°C by 160°C/hour

• increasing the temperature from 800°C to 1250°C by 180°C/hour

• performing uncontrolled cooling between 1250°C and 40°C.

14. The invention is the use of vitrified ceramic products containing silica aerogel compounds as components in the construction of commercial products such as sinks, sink feet, toilets, reservoirs, bidets, urinals, closets, kitchen sinks, bathtubs, shower trays in different designs or sizes.