Properties of porcelain and its application

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

The term "porcelain" refers to a wide range of ceramic products that are made at high temperatures. Their distinguishing features are a smooth surface and low porosity. These properties of porcelain are widely demanded to this day. It is difficult to find some industry or national economy, wherever it is used.

The most common decorative porcelain, as well as chemical glassware, dental crowns and electrical insulators. Usually white or off-white, for "baking" this wonderful material arrives as an unpresentable piece of ceramics, which will acquire its familiar form only after roasting in high-temperature ovens.

The advantages of Chinese services

In this article, we will discuss the properties and types of porcelain. You will understand why this material was so popular all over the world that huge expeditions were equipped to buy it. For a beautiful service, which today you can buy in any store, then you could get killed.

Oddly enough, but the products of Chinese masters with today's ceramics are only relatives, but not direct ones. To see this, it suffices to recall the basic propertiesporcelain, which came out of the workshops of the Middle Kingdom. The materials are very similar to each other: both modern and ancient porcelain can be glazed or "natural". But simple ceramics are much softer. And a high-quality service cannot be made from it.

Why is this happening?

Such properties of porcelain, such as strength and heat resistance, are the fruit of high temperatures at which true Chinese ceramics are produced. It is produced at a temperature of 2,650 degrees Fahrenheit (1,454 degrees Celsius). Compare that to 2,200 degrees Fahrenheit (1,204 degrees Celsius) for plain porcelain. Since the second material is of lower quality, it is not used in the chemical industry and other technological branches of science. In addition, it is Chinese porcelain of the highest quality that is transparent to the light. Rough ceramics cannot give such an effect.

Spy passions

"Hard paste", or true porcelain, first appeared in China during the Tang Dynasty (618-907). But really high-quality products, in their properties in no way inferior to modern ones, became known to the world only during the Yuan Dynasty (1279-1368). Early Chinese porcelain consisted of kaolin (china clay) and pegmatite, a rough type of granite.

It was unknown to European potters until the import of Chinese equipment during the Middle Ages. Europeans tried to duplicate the properties of porcelain, but did not succeed in this matter. Since analyze its chemical composition they wereunable, the products produced by them resembled elegant, fragile and at the same time durable dishes only externally. It turned out like that. Real spy wars unfolded to get the secret of true porcelain production, but the Chinese kept their secret more than life.

Why was this material so popular? The reason is the excellent physical properties of porcelain. It is stronger than ordinary ceramics, has a high thermal conductivity, which makes it possible to brew excellent tea in teapots from it. In addition, due to the glaze, porcelain has an extremely low soiling, staining only under the influence of synthetic pigments. Cups from ancient Chinese services remain white after many centuries.

Ersatzy

After mixing glass with tin oxide to make an opaque material, European artisans tried to combine clay and frosted glass. These alternatives became known as "soft paste" or artificial porcelain. But two unpleasant circumstances were upsetting: all these materials turned out to be too soft, it was impossible to make really thin, elegant products from them, and the production costs were too high. In short, the properties of "ersatz-type" porcelain were far from perfect.

There is evidence that our masters also mastered the art of producing true porcelain, but all the secrets of Russian ceramics were lost during the Tatar-Mongol invasion, when entire cities were burned along with all their inhabitants. Some breakthrough was also achievedthe English. They created a "bone" kind of material.

But what is bone china, the main properties of which made it incredibly popular in old Europe?

History of Creation

In 1707, two Germans named Ehrenfried W alther von Chimhaus and Johan Friedrich Bottger discover a more "sane" method of production that uses clay and finely ground feldspar. In the 17th century, English artisans learned through experimentation that porcelain, almost identical to Chinese porcelain, could be obtained by adding finely ground burnt bones to this mixture.

And later it turned out that the English version allows you to produce transparent ceramics at much lower temperatures, which significantly reduces the cost of production. In addition, porcelain from Foggy Albion fought much worse, was much stronger. So it is not surprising that the British soon filled up half of the Old and almost the entire New World with their services.

What are the properties of bone china? Firstly, products made from it are distinguished by high strength with low weight and thin-walled. Secondly, this type of ceramic cannot be used in the chemical industry, since the substances in its composition react with acids and alkalis.

Raw materials

As we said, the main components of this material are extremely simple: clay, feldspar, minerals with calcium content. Until now, various companies compete with each other, as it was quickly established thatthe properties of porcelain and faience can be radically changed by adding new elements to its composition. Of course, if the experience is successful.

Despite the fact that the composition of the clay varies depending on the place of its extraction, it still turns into glass (which ensures the smoothness of the final product) only at extremely high temperatures. But this is true only for those cases when clays are not mixed with materials whose vitrification threshold is lower. Unlike glass, however, clay is thermally stable, meaning it retains its shape even when heated to a high temperature.

So this material is truly unique as it combines the low porosity of glass with the stability and relative strength of simple ceramic. Kaolin, a hydroaluminosilicate, has been used as the main type of raw material at all times. Feldspar (containing aluminum silicate) and flint, a type of hard quartz, are extremely important ingredients in any type of porcelain. They melt when heated, binding the material together.

Quartz - the "heart" of porcelain

This is the key to strength. The properties of porcelain (and its use) are largely due to this particular characteristic: it breaks poorly (compared to glass), and small distances between particles ensure the impermeability of the material to air, water, and other compounds.

Quartz is an "alloy" of oxygen and silicon, the two most abundant elements in the earth's crust. It has three functional forms: directly quartz (crystals), opal(amorphous variety) and sand (mixed, dirty fraction). In general, quartz has long been used in handicraft production. Porcelain may also contain alumina and soapstone, better known as "soapstone".

Production process

After the raw materials are selected and weighed, they go to production. First, it is cleaned and ground to very fine fractions. After that, all components are mixed in the required proportion, depending both on the production conditions and on the characteristics of the final products. As soon as the latter are formed, they can be sent to the oven immediately, or they are pre-cleaned and then covered with a layer of glaze.

Of course, crushed glass first acts in its role. And only after that, future vases, cups, toilet bowls and dental crowns are sent to the furnace mouth. Now let's look at each stage separately. After all, the properties of porcelain and its application depend on their success!

Crushing raw materials

Perhaps, this is one of the most important operations, since the quality of the final product depends on the thoroughness of its implementation. Crushing is carried out using huge mechanical drum crushers. On the second pass, the particle size is brought to 0.25 cm. To turn the feedstock into fine dust, special ball crushers are used. These are huge steel cylinders filled with metal balls. When the whole structure rotates, the particles of raw materials turn into a homogeneous mass of extremely fine grinding.

Cleaning and blending

The mixture is passed through fine filters and then fed to a special "conveyor", which is an inclined steel sheets. They vibrate, as a result of which the raw material is not only automatically mixed, but also sorted, since the largest particles are pushed up. If wetted material is required, water is automatically sprayed into the line.

Sometimes filters with powerful magnets are used, as the latter can remove the smallest impurities of iron. The latter, if it gets into the finished product, will give it an undesirable red tint. After that, the finished products are sent to the kiln, where they are fired at the temperatures already indicated by us.

On what production conditions can product properties depend?

It should be noted that during the final firing there are many processes that directly affect the properties of cold porcelain. Firstly, all carbon organic impurities are burned, excess water is evaporated, various gaseous fractions come out of the thickness of the future product. If at the same time the temperature is not brought to 1100 degrees Celsius, then silicon and other components of the glaze will not be able to melt, which means they will not form a smooth and chemically neutral layer on the ceramic surface.

In addition, these connections are necessary to reduce the distance between the particles of materials, for a more reliable connection between them. Once the desired density has been reached,the product is cooled, as a result of which the glaze “pulls together”, becomes smooth and especially durable.

Results

So why are we describing all this? The thing is that the properties of this material are closely dependent on the features and conditions of its manufacture. For example, strength depends on the percentage of feldspar in the mass, and the number of pores in porcelain is the smaller, the more feldspar. As the quartz and the residue obtained from the decomposition of the clay substance dissolve in the glass, the skeleton of the porcelain material becomes weaker and the deformations increase. Depending on the fineness of quartz grinding, mass composition, temperature and duration of firing, the glassy phase contains from 15 to 40% of all quartz introduced into the mass. The more it is, the porcelain is thinner and "airier".

Properties of ceramic materials as dielectrics are characterized mainly by resistance to the passage of electric current in the material and on the surface of the insulator. Distinguish between specific volume and specific surface resistance of porcelain.

Besides this, the chemical properties of porcelain are of great practical importance. More precisely, their absence. Glazed ceramics with the addition of a large amount of feldspar and quartz are chemically neutral. Do you think why the mortars of pharmacists and chemists are made of this material? It is much stronger than glass, but it does not react.

The current state of affairs

Today, ceramics (and porcelain in particular) are experiencing a secondbirth. It turned out that these materials can be used in the production of various types of microelectronics. The importance of this for modern civilization does not need to be explained. Scientists also found that when certain additives are added, the strength of porcelain increases exponentially. Currently, even promising research is underway in the field of creating new types of armor based on it. So not toilet bowls alone!

Finally, this material is becoming increasingly important in medicine. Various prostheses and magnificent dental crowns - the demand for them is increasing every year. So the ancient Chinese invention will remain relevant for a very long time.