Are you curious about advanced materials such as zirconia? Zirconia is a widely used ceramic material with excellent durability, corrosion resistance and thermal stability.
According to research, the zirconia market value in 2023 is close to 5.7 billion US dollars, and it is expected to reach 9.03 billion US dollars by 2030. This shows that zirconia has very good development prospects.
Read the following article and you will have a more comprehensive understanding of zirconia.
Quick Links
- What is Zirconia?
- Crystal Structure of Zirconium Oxide
- Characteristics of Zirconia
- Zirconia Application
- Different Types and Grades of Zirconia
- Zirconia Manufacturing Process
If you don’t have time to read a lot of text, we have prepared some frequently asked user questions that may be able to help you!
What is Zirconia?
Zirconia, with the chemical formula ZrO2, is a white crystalline zirconium oxide. As a widely used ceramic material, it is known as “ceramic steel”. Zirconia was first discovered in the form of the natural mineral baddeleyite. Of course, we can also extract it from zircon by chemical methods. Natural zirconium oxide has very low purity and often contains a lot of impurities. Through artificial synthesis of zirconium oxide, we can obtain zirconium oxide with higher purity.
Crystal Structure of Zirconium Oxide
Zirconia has a very unique crystal structure, and it will present three main crystal phases at different temperatures:
From room temperature to 1170°C, zirconia is monoclinic;
From 1170°C to 2370, zirconia presents a tetragonal phase；
Above 2370°C to the melting point, zirconia presents a cubic phase.
In order to obtain more stable performance, stabilizers such as yttrium oxide Y2O3 are usually added in modern industry to stabilize the crystal structure of zirconia. This stabilized zirconia has better mechanical properties and thermal stability, especially yttrium stabilized zirconia (YSZ), which has become one of the most widely used commercial zirconia materials.
Characteristics of Zirconia
As one of the most common advanced ceramic materials, which properties of zirconium oxide do you want to know most? Below we will explain the various properties of zirconium oxide to you in detail.
|
Characteristic |
Value |
|
Density |
6.05 g/cm³ |
|
Melting Point |
2370°C |
|
Thermal Conductivity |
2-3 W/m·K |
|
Hardness |
13 GPa |
|
Flexural Strength |
1200 MPa |
|
Fracture Toughness |
8 MPa·m<sup>1/2</sup> |
|
Thermal Expansion |
10.5 × 10<sup>-6</sup>/K |
|
Dielectric Constant |
25 (at 1 MHz) |
|
Volume Resistivity |
10<sup>10</sup> Ω·cm |
|
Chemical Stability |
Excellent |
|
Biocompatibility |
Good |
Mechanical Properties
Zirconium oxide has very strong mechanical properties. Its hardness can reach 13 GPa, its bending strength is as high as 1200 MPa, and its fracture toughness is 8 MPa·m1/2. These excellent mechanical properties mean that zirconium oxide has super strong wear resistance and fracture resistance, which allows you to use it in some high-strength applications.
Physical Properties
If your application requires high physical properties of the material, then zirconium oxide will not disappoint you. The basic physical properties of zirconium oxide are as follows:
Density: 6.05 g/cm³
Melting point: 2370°C
Thermal conductivity: 2-3 W/m·K
These properties make zirconium oxide more suitable for some high-temperature precision engineering.
Corrosion Resistance and Biocompatibility
Zirconium oxide has excellent corrosion resistance and shows extremely high chemical stability. It also has good biocompatibility. When used as an implant, it can reduce the human body’s allergy rate. This is why you often see it in medical implants and chemical equipment.
Zirconia Application
Application of Zirconia in Dentistry
Do you want to know why most dentists choose zirconium oxide as a material? Zirconia has revolutionized the field of dental restorations in the past 20 years.
Zirconia Crowns and Bridges
Zirconia can be made into crowns and bridges, and it can also be subdivided into all-ceramic zirconia and layered zirconia.
All-ceramic zirconia: If you choose all-ceramic zirconia, it can give you a strength of up to 1200 MPa, and it is completely metal-free, reducing your chance of allergies, and has a natural dental aesthetic effect in appearance. You can rest assured to use it for more than 15 years.
Layered zirconia: If you are looking for better aesthetic effects, then layered zirconia is a better choice. Its inner layer can provide strong support, while the outer porcelain layer can give you natural and beautiful teeth. At the same time, it can also customize the color and transparency, which can create an optical effect closer to natural teeth.
Advantages of zirconia compared to traditional materials: Compared with metal porcelain crowns (PFM), zirconia does not produce black lines showing on the gum edge, giving you a better aesthetic experience. At the same time, zirconia has better biocompatibility, greatly reducing your risk of metal allergies, and zirconia is stronger than traditional metals.
Dental implants
Zirconium oxide has great advantages as an implant, it can bring you:
More excellent biocompatibility
More fit with your soft tissue
Can reduce the probability of bacterial attachment
More natural aesthetic effect
Advantages of zirconium oxide compared with titanium implants:
Compared with traditional titanium implants, zirconium oxide implants have a lower risk of allergies and a more similar bone bonding rate, which can reduce the trouble of inflammation.
Clinical data show that the success rate of zirconium oxide implants exceeds 95%, the service life can be stable for more than 20 years, and the bone bonding after implantation is stable, and the incidence of complications is lower.
Zirconia Industrial Applications
Do you know why zirconium oxide is called the “super material” in the industry? If you understand its various applications, you will understand that this title is well deserved!
Refractories and high temperature applications
Zirconia has demonstrated excellent performance in various extreme high-temperature environments. It can withstand continuous high temperatures of 1000-2000°C. At the same time, it has excellent thermal shock performance and is still stable even with a sudden temperature change of 250°C.
When you use it for high-temperature furnace lining, it can significantly extend the life of your equipment; in the glass industry, zirconia can also be used as melting tanks and guides; in the metallurgical industry, it is also used as a key to gating systems part.
Cutting tools and knives
Zirconium oxide is extremely hard and has high toughness, so it can be made into cutting tools and knives.
Extremely precise zirconium oxide knives can achieve sub-micron cutting accuracy, suitable for precision machining of difficult-to-machine materials such as carbon fiber and ceramics.
Even ordinary zirconium oxide knives have a service life many times higher than traditional metals, and they will not rust and are non-toxic, providing food safety for you.
Extended reading: A comprehensive guide to ceramic knives
Precision bearings and valves
In the field of precision machinery, zirconia is also extremely critical.
As a bearing, zirconia has a service life 5-10 times longer than traditional steel bearings, and the self-lubricating property of zirconia can reduce the use of lubricating oil.
The most important thing is that the maximum pressure of zirconia can reach 2000 MPa and can work in extreme environments.
As a valve, in some corrosive environments such as chemical and petroleum, zirconia has excellent sealing performance and the leakage rate is almost zero.
Extended reading: Zirconia bearings vs. steel bearings
Laboratory equipment
Why can’t laboratories do without zirconium oxide? You can get the answer by reading on.
Zirconium oxide made into crucibles can withstand extreme temperatures and corrosive environments
Made into grinding media, it can ensure higher purity and avoid sample contamination
Made into laboratory vessels, it has better chemical inertness and will not react with reagents
Made into test equipment components, it can improve accuracy and make data more reliable
And zirconium oxide products have a very long service life and are very cost-effective.
Fuel cells and sensors
In the field of new energy, zirconium oxide also plays a key role. It is the core electrolyte material of solid oxide fuel cells, with excellent ion conductivity and high energy conversion efficiency. It is a key functional material for oxygen sensors and can be used for automobile exhaust detection. It is a high-temperature gas sensor that can work stably even at a high temperature of 800°C.
In some specific fields, the service life of zirconium oxide can reach more than 50,000 hours.
Extended reading: Uses of zirconia ceramics
Different Types and Grades of Zirconia
Zirconium oxide comes in many different types, let me walk you through the unique benefits of each type.
Yttrium-stabilized zirconia (YSZ)
This is the most common commercial zirconia material, usually stabilized by adding 3-8 mol% yttrium oxide. The mechanical strength of yttrium-stabilized zirconia (YSZ) reaches 1200 MPa, and the fracture toughness is 8-10 MPa·m1/2. You can use it to manufacture high-precision dental restorations, industrial precision parts, high-temperature sensor components, etc.
Extended reading: Yttria stabilized zirconia
Magnesium-stabilized zirconia (Mg-PSZ)
If your application requires higher toughness, magnesium-stabilized zirconia (Mg-PSZ) is your better choice. Mg-PSZ is usually stabilized with 8-10 mol% magnesium oxide, and it has excellent thermal shock resistance and higher fracture toughness (15 MPa· m1/2). You can choose to use it for refractory materials, high-temperature valve parts, and grinding balls and grinding media.
Zirconia Toughened Alumina (ZTA)
ZTA is a composite material that combines the advantages of two ceramic materials. It contains 10-30% zirconium oxide particles, has a hardness of up to 18 GPa, and its toughness has been significantly improved. It is suitable for a variety of high-performance cutting tools, biomedical implants and wear-resistant parts.
Cubic Zirconia
Cubic zirconia is a gemstone very similar to diamond, with unique optical properties, and is an affordable alternative to diamond.
The refractive index of cubic zirconia is as high as 2.15-2.18, and the Mohs hardness reaches 8.5. Because of its beautiful appearance and optical properties, it is often used in high-end jewelry and optical components.
Extended reading: What is cubic zirconia?
Zirconia Manufacturing Process
So how is zirconia manufactured? Let’s take a closer look at this sophisticated manufacturing process.
Raw material extraction and processing
The raw material needs to be processed for zircon ore. The zircon ore is crushed into small particles by mechanical crushing equipment. Then, the density difference between zircon ore and impurities is used to quickly remove unwanted impurities through gravity sorting technology. Of course, strong magnetic impurities such as some iron mineral impurities can also be removed through the weak magnetism of zircon.
Chemical decomposition
There are three main processes for chemical decomposition: chemical decomposition, thermal decomposition and mechanical decomposition. Chemical decomposition mainly involves reacting zircon ore with alkali or acid, and then converting it into soluble compounds such as sodium zirconate or ammonium zirconate; thermal decomposition is to thermally decompose the mineral at high temperature to destroy the crystal structure and make it easier to purify; mechanical decomposition is to pulverize zircon by ball milling to increase the reaction surface area.
Purification process
The purification process is divided into dissolution separation, chemical precipitation and impurity removal. The decomposed zirconium compound needs to be dissolved in water or acidic solution to form a soluble zirconium salt, and then a precipitant (such as ammonia or oxalic acid) is added to precipitate the zirconium salt into an insoluble zirconium compound, such as zirconium hydroxide or zirconium oxalate. Finally, the impurities are further removed through ion exchange technology.
Zirconia synthesis
There are many industrial synthesis methods for zirconium oxide, mainly the following methods.
Pyrolysis dissociation method: Use high temperature to decompose zirconium salt into zirconium oxide to form dense particles.
Chloride process: Convert zirconium ore into zirconium chloride and pyrolyze it into zirconium oxide; this process has high purity, but the cost is also high
Carbonization process: Reduce and decompose zirconium ore in carbon, then oxidize to obtain zirconium oxide.
Melting process: Use high temperature melting method to synthesize single crystal zirconium oxide
Sol-gel method: First prepare zirconium oxide gel, then heat treat to obtain nanoparticles or films. This method is mainly used to manufacture high-performance nano zirconium oxide.
Structural control process
The structural control processes of zirconia mainly include crystal phase stabilization treatment, heat treatment, surface modification, etc.
1. Zirconia has multiple crystal phases. Adding stabilizers can control the crystal phase and improve its performance:
Adding Y2O3: Stabilizing the tetragonal and cubic phases can improve the crack propagation resistance of zirconia.
Adding MgO: It can improve thermal shock resistance.
Adding CaO: It is more conducive to high temperature applications
2. In the heat treatment process, more precise temperature control can ensure uniform grain size; reasonable control of sintering time is beneficial to density and mechanical properties; adding inert gas or reducing gas during sintering can effectively reduce the generation of impurities.
3. The surface modification and processing of zirconia mainly involves coating a protective layer on the surface of zirconia, which can increase its wear resistance and chemical stability. Laser cutting, CNC precision grinding and other technologies can also be used to make various complex shapes and industrial ceramic parts.
Quality inspection and control
The final step of the process is testing. The main testing methods include using XRF (X-ray fluorescence spectroscopy) to analyze the chemical purity of zirconium oxide; using XRD (X-ray diffraction) to determine the crystal phase distribution of zirconium oxide; using ICP-MS (inductively coupled plasma mass spectrometry) to detect trace impurity content, etc.
FAQ
What is zirconia made of？
Zirconia is an advanced ceramic material with the chemical formula ZrO2. Zirconia is mainly extracted from zircon minerals and then formed through precise chemical processing.
This material combines the beauty of ceramics with the strength of metals and is the material of choice for dental applications.
Zirconia vs titanium implants？
In the field of dental implants, zirconium oxide and titanium each have their own advantages. Zirconium oxide can provide you with better aesthetic effects and biocompatibility. You can use zirconium oxide as an implant to reduce the possibility of allergies and it is more suitable for the front teeth area. Titanium implants have longer clinical experience support and lower costs.
How much does a zirconia crown cost？
The market price of zirconia crowns in the United States is generally between $500 and $1,200. The specific price is affected by many factors, so it is recommended that you consult an expert at a professional institution.
Do zirconia crowns stain？
Zirconia crowns have excellent color stability and will not change or stain over time, so you can rest assured. Zirconia can resist coloring from food pigments such as coffee, tea and red wine. However, you still need to pay attention to oral hygiene at all times. Pay attention to 1 to ensure the health of the natural teeth and gums around the crown.
How long do zirconia implants last？
Clinical studies have shown that the life expectancy of zirconia implants can reach 15-20 years or even longer, and the success rate of implantation is over 95%. You only need to pay attention to oral hygiene and perform regular care and cleaning to ensure the long-term stability of the implant in your mouth. We recommend that you have a professional checkup once a year.
Zirconia vs porcelain crown？
There are significant differences between zirconia and traditional porcelain crowns in terms of material structure, strength, and aesthetics. Porcelain teeth are made of ceramic materials and have good aesthetics, but their strength is relatively low. If you eat very hard food, the porcelain is likely to break. In contrast, zirconia crowns are a new generation of ceramic materials with a hardness of up to 1200MPa, which is 3-4 times that of ordinary porcelain. In terms of light transmittance and aesthetics, zirconia crowns are comparable to porcelain crowns. Comparable, but more durable.
Is zirconia safe？
Zirconia is one of the most biocompatible materials in the dental field. You don’t have to worry about its safety. The U.S. Food and Drug Administration (FDA) has approved zirconium oxide for medical implants, and a large number of clinical studies have confirmed that zirconium oxide does not cause allergic reactions or produce substances that are harmful to the human body. At the same time, the surface of zirconium oxide is smooth, and it is not easy to retain food and bacteria, which can reduce your risk of inflammation. Zirconia is an oxide and does not contain metal components. It will not cause metal allergies or produce a metallic taste in your mouth.
Zirconia crown vs PFM？
Compared with traditional metal porcelain crowns (PFM), zirconia has many advantages. First of all, zirconia is not metal, does not cause, there is no metal allergy, and avoids the problem of black lines on the gum edge. Secondly, the strength and durability of zirconia are better than PFM, and there is no risk of porcelain peeling.
In terms of aesthetics, zirconia can better simulate the light transmittance of natural teeth and present a better visual effect. Although the initial cost of zirconia is higher, you need to consider that it has a longer service life and better aesthetic effects. Overall, zirconia is more cost-effective.
Summarize
Zirconia, a high-performance material, has been used in every aspect of our lives. I hope you will have a deeper understanding of zirconia after reading this article.