Ceramic Powder Preparation Solution

Ceramic powder preparation methods mainly include two kinds:

Pulverization method: mechanical crushing (impact crushing, ball grinding, planetary grinding, vibration grinding, etc.), airflow crushing. Impurities, more than 1μm.

Synthesis method: solid phase method, liquid phase method and gas phase method. Purity, controllable particle size, good uniformity, fine particles.

(1) Solid phase method

A. Sintering method: a(s)+b(s)→c(s) ten days (g)

b. Basic form of thermal decomposition reaction (s represents solid phase, g represents gas phase) : s1→s2+g1

c. Combination reaction method: a(s)+b(s)→c(s)+d(g)

d. REDOX or reductive carbonization, reductive nitriding, such as: 3sio2+6c+2n2→si3n4+6co

(2) liquid phase method (salt solution → salt crystal or hydroxide → powder)

a. Chemical coprecipitation

b. Sol-gel method

c. Spray thermal decomposition

(3) Gas phase method

Batching and Molding Process

There are two main methods of ingredient calculation: ingredient calculation with known stoichiometry and ingredient calculation based on chemical composition.

There are two main mixing methods: dry mixing and wet mixing. Attention should be paid to the feeding procedure and the use of mixing media.

Plasticizing: refers to the use of plasticizing agent, so that the raw material billet has plasticity, and plasticity refers to the deformation of the billet without cracks under the action of external force. Plasticizer generally has two categories: one is inorganic plasticizer, the other is organic plasticizer.

Granulation: it is to add plasticizer to the fine raw material to make the particle with coarser particle size, a certain degree of false particle gradation and good fluidity. Granulation methods can be divided into general granulation method, pressure granulation method, spray granulation method, freeze drying method and so on.

The process of further processing ceramic powder and blank into blank body is called molding. Forming methods mainly include: dry pressing forming, isostatic pressing forming, plastic forming, hot die casting forming and flow forming.

What Mineral Materials Are Commonly Used In Ceramic Preparation?

Most of the raw materials used in ceramics and other silicate products are natural minerals or rocks, which are mostly silicate minerals. These raw material variety, rich resources, are widely distributed in the earth's crust, which provides favorable conditions for the development of ceramic industry, early ceramic products, are made of clay minerals content of a single material, then, with the development of ceramic technology and the improvement of product performance requirements, people gradually joined other mineral raw materials in stock, In addition to clay as plastic raw materials, quartz is also appropriately added as raw materials from barren soil, feldspar and other minerals containing alkali metals and alkaline earth metals are added as flux raw materials. At present, there is no unified method for the classification of ceramic raw materials. According to the process characteristics of raw materials, they are generally divided into four categories: plastic raw materials, barren raw materials, fluxing raw materials and functional raw materials.

Plastic raw material

The mineral composition of plastic raw materials is mainly clay minerals, which are silicate of layered structure, and their particles generally belong to the following microscopic particle size (<10μm), and have certain plasticity of minerals. Such as kaolin, multi-water high ridge soil, bentonite, China clay and so on. Plastic raw materials mainly play the role of plasticizing and combining in production, which endowing the plasticity and grouting forming properties of billet, ensuring the strength of dry billet and various service properties after firing, such as mechanical strength, thermal stability, chemical stability, etc., they are the foundation of forming and the foundation of clay ceramics.

Desert sexual material

The mineral composition of raw materials from barren soil is mainly non-plastic silicon and aluminum oxides and oxygenated salts. Such as quartz, opal pyroxite, clay calcined after clinker, waste porcelain powder. The barren raw materials play a role in reducing the viscosity of the billet in the production. After firing, part of the quartz is dissolved in the feldspar glass, which improves the viscosity of the liquid phase and prevents deformation at high temperature. After cooling, it plays a skeleton role in the porcelain billet.

Fluxing raw material

The mineral composition of flux raw materials is mainly alkali metals, oxides of alkali earth metals and oxygenated salts. Such as feldspar, limestone, dolomite, talc, lithium mica, granite and so on. They play a role in the production of melting, after high temperature melting can dissolve a part of quartz and high mountain soil decomposition products, after melting high viscosity glass can play a high temperature cementation. At room temperature, it also plays a role in reducing viscosity.

Functional raw material

In addition to the above three categories of raw materials other raw materials and auxiliary raw materials are collectively referred to as functional raw materials. Such as zinc oxide, zirconia, color materials, electrolytes and so on. They do not play a major role in production, nor are they the necessary components of porcelain, generally a small amount of addition can significantly improve the performance of some aspects of the product, sometimes in order to improve the glaze process performance without affecting the performance of the product, so as to facilitate the realization of the production process.

Main Process Of Nanometer Ceramic Preparation Method

The main process of nanometer ceramic preparation method has three steps, namely the preparation of nanometer powder, nanometer ceramic molding and nanometer ceramic sintering. 

Step one: preparation of nano-powder. 

The preparation of nanometer powders is the most important step in the production of nanometer ceramics. In a way, it can be said that nanometer powder determines the quality of sintered nano ceramic. 

At present, there are two main methods for preparing nano-powder, one is the gas phase synthesis method, this is a very practical method for preparing nano powder. The method can prepare nano oxide powder, also can prepare rice non oxide powder, the biggest advantage of the gas phase synthesis method is the prepared nano powder high purity, sintered nano ceramic surface purity is extremely high. One is the condensation method, which is mainly used in the preparation of recombination oxide nano-ceramic materials.

Step two: nano ceramic molding. 

After the preparation of nanometer powder is completed, the powder can be added to the ceramic production material, and then production take the shape you want.

Step three: nano ceramic sintering. 

Once the nanoceramic has been molded, the final step is sintering. The sintering process is to make sodium rice powder is combined with each other inside the ceramic, and finally becomes the nano-ceramic product with fixed shape.

Sintering of Ceramics

Sintering refers to the densification process of porous ceramic billet with reduced surface area, porosity and mechanical properties at high temperature.

Ceramic sintering process is generally divided into five stages: 

(1) low temperature stage (room temperature to 300℃ or so). 

(2) Intermediate temperature stage (also known as decomposition and oxidation stage, 300 to 950℃). 

(3) High temperature stage (950℃ to firing temperature). 

(4) heat preservation stage. 

(5) The cooling stage.

Commonly used sintering methods mainly include: 

(1) atmospheric pressure sintering (atmospheric pressure). 

(2) hot pressing sintering (pressure). 

(3) hot isostatic sintering and discharge plasma sintering (high temperature and constant pressure). 

(4) atmosphere sintering (oxidation, gas). 

(5) Reaction sintering (gas phase or liquid phase is added to obtain certain strength and precision). 

(6) Microwave sintering. 

(7) Explosion sintering (explosion produces high temperature and high pressure), etc.

Ceramic sintering post treatment technology

Common follow-up processing methods include surface glazing, mechanical processing and surface metallization.

Glazing: 

(1) to improve the mechanical strength and heat shock resistance of porcelain. 

(2) Prevent low pressure discharge on the workpiece surface. 

(3) improve the moisture-proof function of porcelain pieces.

Machining: can make ceramic products to meet the requirements of dimensional tolerance, also can improve the surface finish of ceramic products or remove surface defects. The methods include grinding, laser and ultrasonic machining.

Metallization: In order to meet the needs of electrical properties or realize the sealing of ceramics and metals, it is necessary to firmly plating a layer of metal film on the surface of ceramics, common ceramic metallization methods are silver, electroplating method, etc. The sealing forms of ceramic and metal include glass glaze sealing, metal welding sealing, activated gold layer sealing, laser welding, solid phase sealing and so on.