Home > News > Content

Zirconia Sintering Principle

Hangzhou JWG Technology Co.Ltd | Updated: Sep 05, 2017

Sintering principle of zirconia ceramics

Zirconia ceramics have excellent properties of melting point and boiling point, high hardness, low temperature and electrical conductivity. Zirconia ceramic ware has 3 medium crystal type and belongs to polycrystalline phase transition. Stable low temperature phase is monoclinal phase; Higher than 1000 °, sifang phase gradually formed; Higher than 2370 °, transformed into cubic phase. Zirconia ceramics have high hardness, high strength, high toughness, high abrasion resistance and chemical resistance and so on. Zirconia ceramics have been widely used in refractory materials, machinery, electronics, optics, aerospace, biology, chemistry and so on.

The technical method of densification of granular alumina ceramic and forming solid material is called sintering. The sintering of the particles in the body cavity of the body is eliminated, and the small amount of gas and the organic matter are excluded, so that the particles can grow and combine with each other to form a new material. Zirconia ceramics are most widely used in heating devices. In addition to the normal pressure sintering, the pressure sintering and thermal pressure sintering and so on. Continuous hot-pressed sintering may increase production, but the equipment and mold expenses are too high, and the product length is limited due to the axial heating. Hot and static pressure is used as pressure transfer medium with high temperature and high pressure. It has the advantages of homogeneous heating and is suitable for sintering of complex shape products. Zirconia ceramics have been improved by 30 ~ 50% due to uniform structure. Increase the heat pressure sintering by 10-15%. As a result, some high-value zirconia ceramic or national defense need special parts, such as ceramic bearing, reflector, nuclear fuel and barrel and other products, hot isostatic pressing sintering method.

Some zirconia ceramic parts need to be refined after sintering. If used as artificial bone products, the surface has a high degree of finish, such as mirror, to increase the lubrication. Due to the high hardness of zirconia ceramics, it is necessary to finish the finishing process with more hard abrasive polishing brick materials. Such as SIC, B4C or diamond. It is generally used for grinding, grinding and finishing surface. It can be used for grinding and polishing of Al203 micro powder or diamond paste with < 1 mu m micron. In addition, laser processing and ultrasonic machining of grinding and polishing can also be adopted.

Introduction to the production process of zirconia ceramics

Zirconia ceramics have high temperature and thermal shock resistance. High temperature resistance to creep and low appearance. Zirconia ceramics have strong chemical stability and high temperature resistance. The thermocouple protection structure is used with traditional ceramic structure parts. Because ordinary ceramic structure happen easily and inert gas in high temperature chemical reactions and softening, and zirconia ceramic and inert gas no reaction, so as to avoid the ceramic structure and gas contact, zirconia ceramic effectively improve the service life of the thermocouple.

In the industrial production of many situations will be applied to various types of zirconia ceramic, this shows fully convincingly that zirconia ceramic has many excellent performance compared with other materials, will be popular in the industry. How is this good zirconia ceramics produced?

At present, zirconia ceramics are mainly used for the protection and insulation of thermocouple thermometer. It can also be used in the furnace tube of industrial resistance furnace, experimental electric furnace and heat treatment furnace. In addition, steel and chemical analysis of carbon pipe and sulfur tube, and other anti-high temperature, acid and alkali corrosion insulation instrument components should be made of ceramic ceramic parts. It appears that zirconia ceramic parts use its powerful mechanical strength and thermal shock resistance. Good thermal conductivity and insulation; And the high degree of softening temperature, which has been used in many industries, is of great significance.

Zirconia ceramic production technology process is generally divided into three main steps, to guarantee the quality of zirconia ceramic will each link, the first is as a raw material of the preparation of ceramic powder. If the ceramic ware is made, there is a ready-made granulated powder in the market. If you need to control your own ingredients, you need to buy a ball mill and a ball and a spray dryer.

Once the material has been made, it can begin to suppress the molding. For a flaky product less than 2 mm, you can consider the method of using the gel forming type. For zirconia ceramics larger than 2 mm, the method of pressing machine is considered. Then the sintering and processing are followed. If the zirconia ceramic parts are made in large quantities, they can be continuously produced by tunnel kiln. And the processing mainly depends on the complex degree of the product, some ceramics are not needed to process, can be sold directly.

Hangzhou JWG Technology Co.Ltd