Than the constructional ceramics on the basis of zirconium dioxide is remarkable?
the Polycrystalline materials received by agglomeration of nonmetallic powders are called ceramics. Concrete and various knitting are similar on properties to ceramics. The monolithic body in them is also formed of powders, however not due to agglomeration, and as a result of chemical reactions of hydration.
The ceramics surpasses other materials in the hardness, the module of elasticity and wear resistance. Therefore it is irreplaceable as material for production of the abrasive and cutting tools. The low coefficient of friction and resistance to influence of acids and alkalis belong to advantages of ceramics.
On the range of properties ceramic materials - champions. The technical ceramics works in wider, in comparison with other materials, the range of temperatures.
The monolithic ceramics has the high specific durability and resistance to oxidation at the increased temperatures, but the low impact strength, low resistance to thermal and mechanical blows, and also to distribution of cracks. Fragility - the main lack of ceramics.
The usual household ceramics is received by clay roasting. But there is also other ceramics at which production clay is not used unless in the form of the small impurity facilitating agglomeration. In turn, such ceramics is divided into two big groups: ceramics on the basis of oxides of metals and ceramics on the basis of diamondlike connections - carbides, nitrides, borid, etc.
Today we will get acquainted with constructional ceramics on the basis of zirconium dioxide. The ceramics on the basis of polycrystalline dioxide of the zirconium stabilized by yttrium oxide is mechanically strong and possesses high viscosity of destruction.
Cerium dioxide also stabilizes zirconium dioxide that increases viscosity of destruction in comparison with usual dioxide of zirconium. At this ceramics viscosity of destruction is on average 2,5 times higher, than at other types of ceramics. The Temperature Coefficient of Linear Expansion (TCLE) of zirconium ceramics is close to cast iron TKLR, make temperature resistant ceramic overlays for pig-iron pistons of it.
The ceramics suitable for production of turbine shovels, receive from mix of oxides of zirconium and aluminum. From - for phase transformations of oxide of zirconium and change in this regard of its volume in grains of oxide of aluminum there is a set of microcracks which serve as an obstacle for growth of destructive cracks, extinguish tension arising in shovels at big shock loadings. As a result of it the ceramics durability, viscosity of destruction and resistance of thermal fatigue increases.
Unfortunately, the share of our country in the world market of technical ceramics is insignificant. More than two thirds it are made by Japan. About a technological level of the Japanese developments in the field of constructional ceramics it is possible to judge by the following example: make the springs applied in those areas of equipment where metal cannot be used of the ceramics created on the basis of partially stabilized zirconium dioxide. Such springs can work at high temperature, well resist wear, it is easier, than steel, not magnitna also are electroinsulators.