Do you want to know how many types of zirconia there are? Not 6 or 7 these are 17 types based on different classification criterias. All of these types have got their unique role in manufacturing because of their varying properties like strength, corrosion resistance, thermal resistance, chemical inactivity and flexibility.
Let’s know them without further ado.
What is zirconia and how many different classes it has?
Zirconia or zirconium oxide (ZrO2) is a durable, biocompatible, heatresistant ceramic structure which exists as part of other minerals. German chemist Martin Heinrich Klaproth first discovered it in 1789 as the mineral zircon (ZrSiO₄ ). He isolated oxides from the minerals and named them as zirconia. However, only in 1824, for the first time, a Swedish chemist, Jöns Jakob Berzelius, separated zirconium from the mineral zircon. This powder-like white zirconia, also has incredible resistance against crack propagation and thermal shocks that come from stabilization enhancements. Plus, it can withstand harsh chemicals.
These exceptional mechanical properties make zirconia suitable for manufacturing ceramic knives, medical tools and equipment, industrial tools, aerospace and electrical insulation. At advanced levels, it also has applications like thermal barrier coatings, catalytic converters, oxygen sensors and fuel cell membranes. While its biocompatibility further makes it an excellent choice for manufacturing dental crowns and medical implants.
At normal temperatures, zirconia maintains its monoclinic crystalline form. However, moving towards its melting point of 2716 ℃, zirconia transitions from monoclinic form to tetragonal zirconia (TZP), cubic zirconia, and fluorite structures.
For instance:
● At 1170 ℃, zirconia has a tetragonal shape.
● Progressing to 2370 ℃, it adopts a cubic structure. This is highly popular in jewelry making because it fakes diamonds.
● Then, above 2370 ℃, before hitting its melting point of 2716 ℃, it maintains a fluorite form. Overall, these transitions affect the stability and other properties of zirconia. Zirconia is classified into different types following diverse criteria.
● Stabilization method by adding oxides like yttria or calcium and other minerals.
● Composite structures
● Special compositions and application
● Processing and properties
● Special applications
17 types of zirconia explained
Continuously developing zirconia has 17 of the most popular types used in the manufacturing industry including dental implants and orthopedics.
Types of zirconia, based on stabilization methods
1. Monoclinic Zirconia
This is the most stable and pure form of zirconia at standard environment temperatures. More prone to brittleness, monoclinic zirconia lacks essential toughness and durability. Therefore, stabilization towards tetragonal zirconia polycrystals (TZP) is crucial to use it.
2. Tetragonal Zirconia Stabilized at higher temperature ranges. Its improved toughness and durability make it suitable for dental and high-performance ceramics applications.
3. Partially Stabilized Zirconia (PSZ) Comprising a mix of monoclinic and tetragonal zirconia, this type is stabilized using yttria or calcia (calcium). Choice of the stabilizer used further determines the type of PSZ and its properties. Overall, it has higher toughness and resistance.
4. Fully Stabilized Zirconia (FSZ) Pure cubic zirconia’s stabilized form, known as FSZ, features outstanding thermal resistance and chemical stability. For this reason it stands out as a perfect match for producing thermal barrier coatings and sensors.
5. Ceria Stabilized Zirconia (CSZ) When zirconia is stabilized with cerium oxide (CeO2), it attains incredible stability. You know it as Ceria Stabilized Zirconia (CSZ). This stability combines with CSZ’s fracture resistance and low-temperature degradation resistance properties. These unique properties make Ceria Stabilized Zirconia an ideal choice for biomedical and industrial applications.
Types of zirconia based on composite structures
1. Zirconia Toughened Alumina (ZTA)
Without any confusion, ZTA is simply a composite of zirconia and alumina. Their fusion results in better mechanical hardness and durability. These infused properties make ZTA suitable for several applications like dental, joint replacement, cutting tools, engine parts, and mining tools.
2. NanoZR
NanoZR is a blend of nanoscale zirconia particles and alumina. You can think of it as the next-level version of ZTA because of its toughness and thermal stability. These exceptional characteristics make nano zirconia a go-to for biomedical applications, high-temperature conditions and dental implants.
3. Multilayer Zirconia (M3Y, M4Y, M5Y, M6Y, and hybrid variants like M3Y-5Y, M3Y-4Y, etc).
These zirconia structures have layers of mix-and-match zirconia compositions, for an improved translucency, besides biochemical suitability and strength. Y in these types refers to yttria (Y₂ O₃ ), while number denotes the number of moles in each variant. For example, in “M3Y”, there are 3 moles of yttria, and 5 moles of yttria in “M5Y.” Layered strength makes multilayer zirconia a superior choice for dental implants.
4. Transformed Toughened Zirconia
This is obtained through tetragonal zirconia by exploiting its stress-induced phase transformation. Its far-fetched durability and wear resistance make it a great choice for cutting tools and dental implants.
Types of zirconia based special compositions and applications
1. Yttria-Stabilized Tetragonal Zirconia Polycrystals (Y-TZP)
With extremely precise toughness and strength, this tetragonal zirconia polycrystal is stabilized with yttria. Its amplified toughness makes it ideal for prosthetic and dental applications.
2. Monolithic zirconia
Among Yttria Stabilized Zirconia polycrystals, another subtype of monolithic zirconia with a single layer has been developed. This solid dental material is exceptionally wear-resistant.
3. Magnesia-Stabilized Zirconia (Mg-PSZ)
Stabilized using magnesium oxide, this type of zirconia has superior thermal shock resistance besides strength. That’s why it’s used in refractory lining and high-temp applications like aerospace.
4. 3Y-HA
This type of zirconia is stabilized with 3-mol% yttria along with hydroxyapatite. Such complex stabilization gives 3Y-HA zirconia its precise biocompatibility, bioactivity and iconic mechanical toughness. Then hydroxyapatite does wonders in addition to these attributes.
There, you have a material that mimics the composition of natural bone. So, the resulting orthopedic implants like hip joint balls stimulate osteoblast activity and have better integration with the bone. They also reduce the risk of bone density loss when the artificial implant is removed. It also shows potential antibacterial effects.
Because of these properties, 3Y-HA zirconia is considered ideal for making bone screws, plates, joint replacements, and load-bearing bone repairs.
5. 3Y
This zirconia type is stabilized combined with 3 mol% yttria, which emphasizes mechanical strength and reduced translucency. This special attribute makes it suitable for dental crowns and prostheses. But if you increase the mol% of yttria, zirconia will lose its strength.
Specialized zirconia types based on processing and properties
1. Low Temperature Degradation (LTD) Zirconia
LTD zirconia is engineered to fight phase degradation caused by any moisture. This translates LTD zirconia’s long-term durability in moist environments: slow degeneration in dental implants (coming through aging) and industrial application.
2. Hot Isostatic Press (HIP) Zirconia
HIP zirconia is processed under special conditions like high pressure and temperature to increase its density. This way it becomes ultra-strong ceramic to meet the demands of top-tier applications. These applications include industrial blades, gap subrings, MWD application sleeves and waterjet plunger elements.
3. Ceramic Injection Molding Zirconia
For ceramic injection molding, Yttria Stabilized Zirconia, MagnesiumStabilized Zirconia and Ceria-Stabilized Zirconia are used. But in the process, the particles’ size is especially kept at about 1μm. This helps to improve the strength and durability of the sintered body.
Additional types based on specific applications
1. 3Y-4Y, M3Y-5Y, and other multilayer variants like M4Y-5Y
Multilayer zirconia combines 3 layers of different yttria zirconias from core to outer layer. It gives a natural teeth-like look and extra strength to highquality dental crowns, bridges and implants. More moles of yttria means more translucent implants — near to natural teeth. However, they’re also less durable because of lacking flexibility.
What types of zirconia are used in dentistry?
In dentistry, most specialized types of zirconia with excellent durability and biocompatibility are used. Among these, Yttria Stabilized Tetragonal Zirconia Polycrystals (Y-TZP), magnesia-stabilized zirconia (Mg-PSZ) and Zirconia Toughened Alumina (ZTA) are used. These zirconia types are used alone or in the form of layered zirconia.
Conclusion
So, these were the most common 17 types of ever-developing zirconia. Therefore, choosing the right zirconia type to fulfill your product quality standards can be challenging. That’s where ceramic manufacturers save you by understanding your needs and making the right product for you.