Ceramics for technical applications
Zirconium oxide is becoming increasingly important in dental medicine, but the versatile material is also enjoying growing popularity in plant and mechanical engineering and many other areas.
Below you will find the relevant information about the material. Colloquially known as zirconium oxide, zirconium oxide (ZrO2) is gaining increasing importance due to its properties. It exhibits
v
Zirconium oxide - From general engineering to dental technology
low thermal conductivity,
high fracture toughness,
high corrosion resistance,
high wear resistance
very good tribological properties and
a thermal expansion similar to cast iron.
After aluminum oxide, zirconia is the most commonly used ceramic material in the technical and consumer sectors. In nature, it is found as the mineral baddeleyite. However, this mineral is not used for the production of ZrO2.
Zircon", i.e. zirconium silicate, is primarily used for this purpose. Zirconium oxide can also be grown in the form of artificial crystals and is known to experts and laymen alike as "zirconia".
Types of ZrO2 zirconia ceramics
Zirconia belongs to the group of so-called oxide ceramics according to its composition. Furthermore, ZrO2 belongs to the family of technical ceramics due to its technically demanding production and its properties.
Up to a temperature of 1,150 °C, the material has a monoclinic lattice structure. In a temperature range between 1,150 °C and 2,350 °C, the structure changes to a tetragonal lattice. At temperatures between 2,350 °C and 2,680 °C, the tetragonal lattice becomes a cubic lattice.
If a lattice transformation from the tetragonal to the monoclinic lattice occurs in the field of technical applications, this can cause problems. The reason for this is an increase in volume associated with the lattice conversion. This increase is about 3 to 5%.
This would result in serious damage or even destruction of sintered components made of pure zirconium oxide. To avoid this effect, tetragonal or cubic modifications are stabilized. This is done by doping, i.e. the incorporation of foreign ions.
Suitable materials for this purpose are
Cerodide (CeO),
magnesium and
calcium oxide (MgO and CaO) or
yttrium oxide (Y2O3).
With this approach, it is possible to benefit from the advantages of the higher strength tetragonal and cubic lattices while stabilizing them under normal conditions. Basically, zirconia ceramics are divided into three types depending on the amount and type of stabilizing substances.
Fully stabilized ZrO2 - also known as cubic or fully stabilized zirconia (CSZ or FSZ).
Foreign oxides are incorporated into the crystal lattice. Thus, even after cooling, the cubic high-temperature structure is retained. The advantage is that there is no disruptive volume jump, and application in the technical spectrum is possible.
Partially Stabilized Zirconia (TZP), Partially Stabilized Zirconia (PSZ)
TZP/ PSZ is of great technical importance. Already at room temperature a coarse cubic phase is present. It is kept metastable in its state by suitable tempering processes or a process control adapted to it. Conversion to the monoclinic phase is successfully prevented, and the microstructure is properly prestressed. This results in an increase in toughness and strength.
Polycrystalline tetragonal ZrO2 or Tetragonal Zirconia Polycrystal (TPZ).
A typical feature of TPZ is an extremely fine-grained microstructure. To achieve it, extremely fine starting powders and low sintering temperatures are used. The particularly fine microstructure and a metastable tetragonal structure provide exceptional mechanical strength. More than 1,500 MPa can be achieved.
In the early days of technical ceramics, magnesium oxide was mainly used for stabilization. Modern generations of ceramics benefit from the higher strength of yttria. It bears the designation Y-TZP. The ZrO2 matrix can be sintered almost completely dense when using yttria. The results are very fine and homogeneous microstructures, which at the same time convince with high strength.
Properties of zirconia
Density
At 5.7 to 6.1 grams per cubic centimeter, the material has a comparatively high density. Among technical ceramics, it is one of the heaviest materials. Why is that? Zirconium itself is already a heavy metal. During production/stabilization, only small amounts of lighter substances, for example magnesium, are added.
Mechanical properties
Zirconium oxide is also impressive in terms of mechanical properties. If the oxide is tetragonally stabilized, it has an extremely fine microstructure, as already mentioned. This enables very good strength values. Furthermore, Vickers hardnesses of 1,200 HV stand for excellent wear resistance.
Chemical resistance
Like all technical ceramics, the material is very chemically resistant to many corrosive media. Since it is also physiologically harmless, it is suitable for the manufacture of various implant materials.
Operating temperatures
The strong bonding forces also allow very high maximum operating temperatures (approx. 1,600 °C). It is virtually impossible for the atoms to oscillate within their lattice position - this makes ZrO2 a poor conductor of heat. At the same time, the material has a coefficient of expansion very similar to that of steel. Engine builders take advantage of this fact and combine the two materials.
Poor conductor of electricity
Unlike metals, zirconium oxide has no free electrons. They are needed to act as charge carriers. Therefore, the material conducts electricity only to a minimal extent. On the other hand, oxygen ions can be conducted well with it. This is of relevance to engineering.
Powder production
To obtain the fine powder, zirconium silicate (alternative designations: zircon, zircon sand) is used as the starting material. Depending on the desired lattice structure, suitable materials are added.
Like all ceramic materials, we process the zirconium oxide by sintering to produce the components you want and need.
Manufacturing process of technical ceramics / zirconium oxide
In order for the zirconia ceramic to meet the application, you need to understand the manufacturing process and discuss the process in detail with experts like BSQ TECH GmbH to get a perfect product in the end. We are always ready to assist you in your development and support you from the prototype phase to the series production phase.
Application of zirconium oxide
Today, zirconium oxide is used in many industries and areas. For example, it is excellently suited for the production of welding rollers for welding technology.
The textile industry also uses the material in many ways, for example for durable thread guides.
Cutting with zirconia
Cutting tools in machining technology can also be realized with it. And who doesn't know them: kitchen knives made of ceramic.
However, the material is only suitable as a cutting material to a limited extent. A cutting process is often associated with vibrating and/or impacting loads. The material has only limited resistance to this.
Flixible Ceramic
The situation is different with so-called Fexible Ceramic. In contrast to the usual standard ceramic, this material has a significantly higher impact strength as well as optimal micro- and macro chip resistance Flexible Ceramic (FC) ceramic knives. Material data can be obtained from BSQ TECH GmbH on request.
Precise cutting
With a high impact ceramic blade, its cutting edge is clean and sharp, the blade cuts like a wire and the cut is clean and precise. The advantage of light knife makes cutting ripe tomatoes, big carrots, fresh fish or chicken breast with high precision and it needs less time and energy, also the experience with it is very satisfying.
Elastic ceramics
The most important and extraordinary feature of Flexible Ceramic (FC) is its elastic behavior, which is unique in the world. It is even better than metal as it allows irreversible deformation.
Hardness Zirconia
High resistance to impact and its superior high hardness makes this blade much more durable than the existing ceramic blades we know today.
New technology - Flexible Ceramic
FC - Flexible Ceramic comes from a breakthrough technology and is the future in cutting applications for household knives but also for all other cutting applications and is injection molded.
This material is now available through BSQ TECH GmbH.
Zirconium oxide in medical technology
The material is becoming increasingly important for medical technology. Thanks to its good biocompatibility, it is being used in more and more areas. Dental medicine, for example, has been using this versatile material for some time to manufacture dental crowns and bridges.
In addition to its good biocompatibility, the material's wear resistance and compressive strength make it ideal for dental implants. Dental prostheses should blend in with the row of natural teeth as invisibly as possible. The appearance of zirconium oxide is quite comparable to real teeth. The natural color of the material and its translucency are decisive factors for this.
Modern medicine has long been able to replace defective and worn-out joints, for example
the hip joint, for example, with an artificial model.
Here, too, the material can demonstrate its advantages. However, this requires a combination with aluminum oxide to achieve an improved degree of hardness. To prevent fractures, the ZrO2 provides the necessary toughness.
Zirconia in the watch industry
Quite apart from medicine and industry, the material finds a completely different field of application in the jewelry industry. Here it is used as an artificially grown crystal with a cubic lattice structure.
Under the designation "zirconia" these
attractive crystals are sold as inexpensive imitation diamonds. From powder to finished product - we are happy to support you all the way. Do you have any questions?
Please feel free to contact us!
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