Zirconia – Zirconium Metal

How Is Zirconia Used in Modern Dentistry

Introduction

Zirconia, or zirconium dioxide (ZrO2), has become a prominent material in modern dentistry due to its exceptional properties. Known for its high strength, biocompatibility, and aesthetic appeal, zirconia is widely used in various dental applications, revolutionizing restorative and cosmetic dentistry.

Properties of Zirconia

High Strength: Zirconia is renowned for its high flexural strength and fracture toughness, making it an ideal material for dental restorations that require durability and resistance to chewing forces.
Biocompatibility: Zirconia is highly biocompatible, meaning it is well-tolerated by the body. This property reduces the risk of allergic reactions and ensures long-term success of dental implants and restorations.
Aesthetic Appeal: With its tooth-like color and translucency, zirconia offers excellent aesthetic results. It can be shaded to match natural teeth, making it suitable for visible restorations.
Corrosion and Wear Resistance: Zirconia is resistant to corrosion and wear, ensuring longevity and maintaining its integrity over time, even in the harsh oral environment.
Low Thermal Conductivity: Zirconia’s low thermal conductivity protects the pulp of the tooth from temperature changes, enhancing patient comfort.

Applications in Dentistry

Crowns and Bridges: Zirconia is extensively used for fabricating dental crowns and bridges due to its strength and natural appearance. It can be used for both anterior and posterior restorations, providing durability and aesthetics.
Dental Implants: Zirconia implants are an alternative to traditional titanium implants. They offer excellent osseointegration, biocompatibility, and a metal-free option for patients with metal sensitivities.
Inlays and Onlays: Zirconia is used for inlays and onlays, providing a strong and durable solution for restoring decayed or damaged teeth while preserving more of the natural tooth structure.
Orthodontic Brackets: Zirconia is used in orthodontic brackets due to its strength and tooth-colored appearance, providing a more aesthetically pleasing alternative to metal brackets.
Veneers: Zirconia veneers are used to improve the appearance of teeth. They are strong, durable, and can be matched to the color of natural teeth, providing a seamless look.
Full Mouth Reconstructions: For patients requiring extensive dental work, zirconia is used in full mouth reconstructions, providing a durable and aesthetically pleasing solution for multiple restorations.

Advantages of Zirconia in Dentistry

Durability: Zirconia’s high strength and resistance to fracture and wear make it one of the most durable materials available for dental restorations.
Aesthetics: Its ability to mimic the natural color and translucency of teeth makes zirconia an excellent choice for visible restorations, enhancing the patient’s smile.
Biocompatibility: Zirconia’s biocompatibility ensures that it integrates well with the body, reducing the risk of adverse reactions and promoting long-term success.
Minimal Preparation: Zirconia restorations often require minimal tooth preparation, preserving more of the natural tooth structure.
Versatility: Zirconia can be used in a wide range of dental applications, from single crowns to full mouth reconstructions, making it a versatile material for various dental needs.

Future Trends and Developments

Improved Aesthetics: Ongoing research is focused on enhancing the aesthetic properties of zirconia, such as improving translucency and color matching, to make it even more indistinguishable from natural teeth.
Enhanced Osseointegration: Developments in surface treatments and coatings aim to improve the osseointegration of zirconia implants, enhancing their stability and success rates.
Digital Dentistry: The integration of CAD/CAM technology with zirconia restorations allows for precise, customized restorations with improved fit and function, reducing the time required for dental procedures.
Bioactive Zirconia: Research is exploring the development of bioactive zirconia that can promote bone growth and integration, further enhancing its suitability for dental implants and other applications.

Conclusion

Zirconia has significantly impacted modern dentistry, offering a combination of strength, biocompatibility, and aesthetic appeal. Its versatility makes it suitable for a wide range of dental applications, from crowns and bridges to implants and veneers.

As technology advances and research continues, the use of zirconia in dentistry is likely to expand, offering even more innovative and effective solutions for dental care. For more information, please check Advanced Refractory Metals (ARM).

6 Products Made from Zirconia

Introduction

In the world of advanced materials, Zirconia, or zirconium dioxide (ZrO2), emerges as a protagonist. It stands out for its remarkable properties, including high strength, durability, and resistance to corrosion and wear. Zirconia has carved its niche across various industries.

Let’s explore the diverse applications and features of zirconia. Hope that you can have a comprehensive understanding of its role in today’s material science landscape.

1. Revolutionizing Dentistry: Crowns and Implants

The advancement of dental materials has always been pivotal in enhancing oral health care. Among these materials, zirconia has emerged as a cornerstone in the field of restorative dentistry. Its unique properties have made it an ideal choice for fabricating dental implants, crowns, and bridges.

It offers a blend of functionality, aesthetics, and durability that surpasses many traditional materials.

–Biocompatibility:

One of the most critical aspects is its biocompatibility. Zirconia excels in this regard, as it is inert and does not react adversely with body tissues. The risk of inflammation, infection, or rejection is significantly reduced. Furthermore, Zirconia-made dental restorations can last for many years without causing any harm to the surrounding oral environment.

–Aesthetic Appeal

In addition to its health benefits, Zirconia is highly prized for its aesthetic qualities. The material’s natural tooth-like color and translucency closely mimic the appearance of natural teeth. Yet, metal-based restorations can sometimes show through the gums or the crowns themselves as a dark line.

–Durability and Strength

Durability is another hallmark of Zirconia-based dental products.

With exceptional strength and resistance to wear and tear, ZrO2 is suitable for use in the high-pressure environment of the mouth.
It can withstand the forces of chewing and biting over extended periods.
Moreover, the material’s resistance to staining and discoloration means that restorations retain their aesthetic appeal for years to come.

2. Enhancing Automotive Performance: Oxygen Sensors

ZrO2 has emerged as a key material in this arena, particularly in the development of advanced oxygen sensors for exhaust systems. These sensors contribute significantly to optimizing fuel combustion, enhancing vehicle efficiency, and reducing harmful emissions.

–High-Temperature Resistance

Zirconia’s exceptional high-temperature resistance makes it an ideal material for use in the harsh environment of vehicle exhaust systems. Zirconia not only survives these temperatures but also maintains its structural integrity and functional properties over time. This durability ensures that oxygen sensors can operate reliably for the lifespan of the vehicle.

–Optimizing Fuel Combustion

The primary function of zirconia-based oxygen sensors is to measure the oxygen levels in a vehicle’s exhaust gases. This information is crucial for the engine’s control unit (ECU) to adjust the air-fuel mixture in real time. This is not just a matter of saving energy and reducing costs for drivers; it also plays a significant role in enhancing the vehicle’s performance.

–Reducing Emissions

Besides, zirconia-based oxygen sensors have a significant positive impact on the environment. By optimizing the combustion process, these sensors help reduce the emission of harmful gases, such as carbon monoxide (CO), nitrogen oxides (NOx), and unburnt hydrocarbons.

3. Powering the Future: Fuel Cells

Central to the operation of SOFCs is Zirconium Dioxide (ZrO2), commonly known as Zirconia. This material’s unique properties are key to the functionality and efficiency of SOFCs, offering a glimpse into the future of clean energy.

–Oxygen Ion Conduction at Elevated Temperatures

One of the most remarkable properties of Zirconia is its ability to conduct oxygen ions at high temperatures.

At these elevated temperatures ranging from 600°C to 1000°C, Zirconia becomes an excellent conductor of oxygen ions.
So, they move freely through the cell’s electrolyte.
They enhance the electrochemical conversion process that occurs in SOFCs, and they transform chemical energy directly into electrical energy without the intermediate step of combustion.

4. Advancing Medical Prosthetics: Hip and Knee Replacements

The medical field uses it in the production of hip and knee prosthetics. This field capitalizes on its wear resistance and biocompatibility.

These prostheses offer patients improved quality of life through durable and reliable joint replacements. They showcase zirconia’s critical role in medical advancements.

5. Precision Manufacturing: Industrial Cutting Tools

Zirconia’s hardness is harnessed in creating cutting tools for precision machining.

These tools can withstand the rigors of cutting and shaping various materials, from metals to composites, ensuring accuracy and efficiency in manufacturing processes.

6. Industrial Durability: Pump and Valve Components

In industries dealing with corrosive substances, its corrosion resistance makes it an ideal material for components like pumps, valves, and seals. This application underscores zirconia’s ability to enhance the longevity and reliability of industrial equipment.

Conclusion

In summary, zirconia’s applications are as diverse as they are impactful. We enhance our smiles with dental implants, power clean energy solutions, and adorn us in sparkling jewelry. The ten remarkable products made from zirconia show not only the material’s versatility.

As we continue to push the boundaries of material science, zirconia’s role in shaping our world remains undisputed. It promises new horizons in technology, medicine, and beyond.

Stanford Advanced Materials (SAM) is proud to present a comprehensive collection of Zirconium products. SAM encompasses everything from zirconium metals to zirconium compounds. We are open to and welcome customized orders to meet your specific requirements. For further details and to explore our offerings, please get in touch with us.

Zirconium Dioxide: A Material of the Future

Introduction:

Zirconium dioxide is also known as zirconia (ZrO2). This ceramic material has garnered significant attention in various industries due to its remarkable properties.

This article explores the features, uses, and future potential of zirconium dioxide. Hope that you can learn more about this material of the future.

Understanding Zirconium Dioxide:

Zirconium dioxide is a white crystalline oxide of zirconium. Its most notable attributes include high melting point, remarkable strength and toughness, excellent wear resistance, and outstanding thermal properties. These characteristics make it an ideal material for numerous advanced applications.

Properties of Zirconium Dioxide:

This advanced material stands out for a unique set of characteristics. ZrO2 has become suitable for a wide range of applications. Its uses range from high-temperature industrial uses to critical roles in the medical field.

High Strength and Toughness: It is notable for its exceptional mechanical strength and toughness. Its strength surpasses most other ceramic materials.
Thermal Stability: It has a very high melting point of around 2700°C or 4900°F. Also, it is notable for excellent thermal stability. So, ZrO2 is suitable for high-temperature applications.
Wear Resistance: Zirconium dioxide exhibits a high degree of hardness and chemical inertness. These two features greatly contribute to its exceptional wear and corrosion resistance. Thus, it has become an ideal material for applications requiring durability and longevity.
Biocompatibility: Zirconium dioxide is biocompatible. It is safe for use in medical implants.

Applications of Zirconium Dioxide:

Zirconium dioxide has widespread applications. Its uses involve the medical field to industrial, automotive, aerospace, and electronic sectors. This broad utility is a testament to zirconia’s effectiveness in meeting specific demands across different domains.

Dental and Medical Industry: Zirconia finds common use in dentistry due to its tooth-like color and strength. You can also find it in orthopedic implants and other medical prosthetics.
Industrial Uses: In the industrial sector, zirconia is useful for manufacturing cutting tools, grinding media, etc. It also serves as an additive in refractory materials due to its high-temperature resistance.
Automotive and Aerospace: Zirconium dioxide finds applications in these industries for thermal barrier coatings on engine components. It provides protection against high temperatures.
Optical and Electronic Applications: Its optical properties find use in fiber optics and other electronic devices.

Innovations and Future Potential:

Zirconium dioxide (zirconia) possesses a dynamic nature and adaptable properties. So, it is a focal point for continuous research and development.

1. Solid Oxide Fuel Cells (SOFCs):

One of the significant innovations is solid oxide fuel cells. Here, zirconium dioxide acts as an electrolyte.
SOFCs with zirconia are notable for their efficiency in energy generation. They offer a more sustainable and environmentally friendly alternative to traditional energy sources.
ZrO2 has high-temperature stability. Thus, it is particularly suitable for this application. ZrO2 enables SOFCs to operate at high efficiencies.

2. Environmental Applications:

Zirconia is useful in environmental applications, particularly in catalysis for pollution control.
Its properties are advantageous in catalytic converters. These converters reduce harmful emissions from vehicles and industrial processes.
This material has the ability to withstand high temperatures and resist corrosion. It is ideal for long-term use in harsh environmental conditions.

3. Future Potential:

The ongoing research is uncovering new potential uses for zirconium dioxide. Its unique properties open doors to a range of future applications.
The material’s role in green technologies and sustainable processes is particularly promising. There are great global efforts to combat climate change and reduce environmental impact.

Challenges and Future Directions:

Despite its advantages, the processing and machining of zirconium dioxide can be challenging and costly. That’s because ZrO2 is extremely hard. Future research focuses on overcoming these challenges and expanding its applications, particularly in sustainable energy and environmental technologies.

Conclusion:

Zirconium dioxide stands out for its unique blend of properties and various applications. From healthcare to high-tech industries, its role is rapidly expanding. That paves the way for innovations that could redefine the use of ceramics in the modern world. As research progresses, the potential of zirconium dioxide continues to grow.

Stanford Advanced Materials (SAM) boasts extensive expertise in the production and provision of top-quality zirconium dioxide products. A variety of Zr products are available on our website. For more information, please do not hesitate to reach us.

Unraveling the Distinctions: Zircon, Zirconia, and Zirconium

Introduction:

Zircon, zirconia, and zirconium constitute a family of materials. Each of them has distinct properties and widespread applications. This exploration delves into their individual characteristics, applications, and pivotal roles across diverse industries and highlights their collective impact on modern technology and manufacturing. Hope that you can have a deep understanding.

Zircon:

Zircon is primarily composed of zirconium silicate. It boasts exceptional durability, heat resistance, and chemical inertness. Its applications span ceramics, refractories, and the production of zirconium compounds, serving as a foundational material in various sectors.

Zirconia (Zirconium Dioxide):

Zirconia is derived from zircon. It is also known as zirconium dioxide (ZrO2). ZrO2 exhibits remarkable strength, and thermal resistance, and finds widespread use in ceramics, and dental prosthetics. It serves as a refractory material across high-temperature industries as well.

Zirconium:

Zirconium is an elemental metal extracted from zircon mineral sands. It showcases high corrosion resistance, low thermal neutron absorption, and compatibility with human tissues. Its uses extend to nuclear reactors, aerospace applications, and medical implants due to its exceptional properties.

Individual Significance and Applications:

Let’s continue with an extended breakdown of the individual characteristics of Zircon, Zirconia, and Zirconium. They have diverse attributes and pivotal roles across multiple industries, technological advancements, and materials science innovations.

1. Zircon’s Diverse Uses:

Durability and Refractory Applications: Zircon’s resilience lends itself to manufacturing high-temperature ceramics, refractory materials, and foundry sands.
Nuclear Industry: It is crucial in nuclear reactors because it has resistance to radiation and low thermal neutron absorption properties.

2. Applications of Zirconia:

Mechanical Strength: Zirconia comes with strength and toughness. These properties render it valuable in dental prosthetics, engineering ceramics, and high-performance applications like ceramic knives.
Biomedical Implants: Its biocompatibility makes it ideal for medical implants, especially in orthopedics and dental surgeries.

3. Zirconium’s Diverse Uses:

Corrosion Resistance: Zirconium’s resistance to corrosion finds application in chemical processing equipment, aerospace components, and nuclear reactors.
Biomedical Compatibility: This feature makes it a sought-after material for medical implants and prosthetics.

Other Compounds of Zirconium:

Zirconium also forms a myriad of compounds. Each of them comes with distinct properties and applications. Some notable compounds beyond zirconium dioxide (zirconia) include:

1. Zirconium Tetrachloride (ZrCl4):

Zirconium tetrachloride is a key precursor in zirconium chemistry. It serves as a vital reagent in various chemical processes. This compound’s role extends to catalysts and metal-organic frameworks (MOFs). It also serves as a reagent in the production of other zirconium compounds. All these uses mark its importance in industrial applications and research endeavors.

2. Zirconium Nitride (ZrN):

Zirconium nitride stands out for its impressive hardness, wear resistance, and golden appearance. So, it is used as a protective coating in the manufacturing of cutting tools. You can also find it as decorative coatings. It is also useful in the aerospace industry. Its ability to enhance the surface properties of materials contributes significantly to the durability and performance of various products.

3. Zirconium Hydroxide (Zr(OH)4):

Zirconium hydroxide is valued for its adsorption properties and chemical stability. It finds utility in water purification, catalysts, and as a precursor in the production of other zirconium compounds. Its role in environmental applications underscores its significance in addressing purification challenges.

Conclusion:

Zircon, zirconia, and zirconium form a trinity of materials. Each of them has distinct attributes and versatile applications. Their collective impact spans industries and drives innovation and advancements in ceramics, nuclear technology, medical sciences, and beyond. They are shaping the landscape of modern technology and paving the way for future developments.

Stanford Advanced Materials (SAM) now offers an extensive range of Zirconium products. Some of the Zirconium products available include zirconium metals, zirconium compounds, etc. Customized order is also welcome. Please contact for more information.

Reference:

[1] Zircon. (2023, November 22). In Wikipedia. https://en.wikipedia.org/wiki/Zircon

Basic Info | Toughening Methods of Zirconia Ceramics

Zirconia (ZrO2) ceramics are special ceramics with unique physical and chemical properties, and their applications in electronic ceramics, functional ceramics and structural ceramics have developed rapidly. However, the fatal shortcomings of zirconia ceramic materials are brittleness, low reliability, and low repeatability, which seriously affect its application range. Only by improving the fracture toughness of zirconia ceramics, strengthening the material and improving its reliability and service life, can zirconia ceramics truly become a widely used new material.

Toughening technology of zirconia ceramics has been a hot spot in ceramics research. At present, ceramic toughening methods mainly include phase change toughening, particle toughening, fiber toughening, self-toughening, diffusion toughening, synergistic toughening, and nano-toughening, etc.

Phase toughening

Phase toughening refers to the metastable tetragonal phase t-ZrO2 undergoing a phase change under the action of the stress field at the crack tip, forming a monoclinic phase, resulting in volume expansion, thereby forming compressive stress on the crack, hindering crack growth, and increasing the role of toughness. In addition, external conditions (such as laser shock, fatigue fracture toughness, low temperature, grain size and content, critical transition energy, etc.) have a great effect on the phase toughening of zirconia ceramics. If the phase transition produces large stress and volume changes, the product is prone to fracture. Therefore, the influence of external factors on the phase toughening of zirconia ceramics should be avoided during production.

Particle toughening

Particle toughening refers to the method of using particles as a toughening agent and adding it to ZrO2 ceramic powder. Although its effect is not as good as whiskers and fibers, if the particle type, particle size, content and matrix material are properly selected, there is still a certain strong effect. The advantage is that it is simple and easy to implement, and it will also improve the high-temperature strength and high-temperature creep performance while toughening. The toughening mechanism of particle toughening mainly includes the refinement of matrix grains and crack-turning bifurcation.

Fiber toughening

The principle of fiber and whisker toughening is that the crystal close to the crack tip adds closing stress to the crack surface due to deformation, offsets the external stress at the crack tip, and passivates the crack propagation, thereby strengthening the toughness. In addition, when cracks are propagated, the frictional force must be overcome when the columnar crystals are pulled out, which also plays the role of toughening.

Self-toughening

Due to the existence of columnar crystals, cracks will be deflected during the fracture process of zirconia ceramics, which will change and increase the path of crack growth, thereby passivating the cracks, increasing the crack growth resistance and achieving toughening.

Diffuse toughening

Diffusion toughening mainly refers to the toughening of the ceramic matrix by the tetragonal ZrO2 particles. In addition to the phase toughening mechanism, there is also a diffusion toughening mechanism of the second phase particles. Before cracks propagate, the internal residual strain energy of the ceramic itself must first be overcome to achieve the purpose of toughening.

Microcrack toughening

Micro-crack toughening refers to adding a tough material at the crack stress tip to cause micro-cracks to achieve the purpose of dispersing stress, reducing the force of crack advance, and thereby increasing the toughness of the material. When a material undergoes a phase transition, it often results in residual strain energy effects and microcracks. Therefore, the effect of phase transition toughening is significant.

Composite toughening

Composite toughening refers to the simultaneous use of several toughening mechanisms during the actual toughening of ZrO2 ceramics, thereby improving the toughening effect of ZrO2 ceramics. In the actual application process, the specific toughening mechanism is selected according to the different properties of the zirconia ceramic material to be prepared.

Nano toughening

At present, there are three main academic viewpoints of nano-toughening, namely: the theory of refinement, trans-crystalline, and “pinning”.

The refinement theory believes that the introduction of nano-phases can suppress the abnormal growth of the matrix grains, refine the matrix structure uniformly, and improve the strength and toughness of the nano-oxide ceramic composites.
The trans-crystalline theory holds that in nanocomposite materials, the matrix particles are densified with the nanoparticles as the core, and the nanoparticles are encapsulated inside the matrix grains to form an “intracrystalline” structure. In this way, the effect of the main grain boundary can be weakened, transgranular fracture is induced, and transgranular fracture instead of intergranular fracture occurs when the material is fractured, thereby improving the strength and toughness of the nano-zirconia ceramic composite material.
The “pinning” theory believes that the nanoparticles existing in the grain boundaries of the matrix produce a “pinning” effect, which limits the occurrence of grain boundary slippage, pores, and creep. The enhancement of grain boundaries leads to the improvement of the toughness of nano-zirconia multiphase ceramic.

Stanford Advanced Materials supplies high-quality zirconium products to meet our customers’ R&D and production needs. Please visit https://www.samaterials.com/ for more information.

Advantages of Zirconia Ceramic Rods

Zirconium oxide ceramic rods have the common advantages of both metal and polymer materials, and they play a very important role because of their numerous advantages and applications. The production process of ceramic rods is cumbersome and requires production processes such as cutting, grinding, and polishing. Despite this, ceramic rods are in high demand compared to other materials of the same type, which has a tendency to go higher because of its advantages.

Excellent Weatherability

Ceramic rods using zirconia or alumina as production materials have obvious advantages over products of the same category. They are highly weather-resistant and have no effect on the surface and substrate of the ceramic rod, whether it is sunlight, rain or moisture. Corrosion-resistant ceramic rods are also very stable in color under ultraviolet light and are in good compliance with international standards in terms of impact resistance, strength, and elasticity.

Strong Stability

Ceramic rods are generally made of zirconia, which is currently a leading technology in the industry. First of all, a zirconia ceramic rod is simpler to clean, with good fire resistance, neither melting nor falling or exploding, and it can remain stable for a long time. Secondly, the ceramic rod is easy to maintain, no need to add any anti-corrosion paint or protective layer on the surface, it is easy to use and has a long service life.

High Readability

The ceramic rods are made of high-precision materials, which enhance the mechanical strength and hardness of the ceramics during high-temperature firing. Therefore, the ceramic rod has a good performance in terms of impact resistance. After a long period of proof and a number of tests, the wear resistance is also strong, and the shape is not damaged in the long-term use. In a variety of harsh working environments, the advantages of ceramic rods are even more pronounced, making acid-resistant ceramic rods the best choice for harsh conditions.

Ceramic rods are widely used in various fields due to their weather resistance, stability, and high wear resistance. In addition to being able to be used in normal environments, the use of ceramic rods not only ensures the normal operation of the instrument, but also does not cause breakage, wear, corrosion, etc., nor damage to the instrument.

Stanford Advanced Materials (SAM) is a global supplier of pure metals, alloys, ceramics, minerals, and rare earth materials since 1994. We supply high-quality zirconia ceramic materials used in aerospace components, medical devices, surgical and dental implants, etc. Please visit https://www.samaterials.com for more information.

How is the Zirconia Industry Laid Out?

Globally, zirconia producers are mainly concentrated in a few countries, mainly including China, Japan, France, the United Kingdom, the United States, and Australia. Companies with a comprehensive zirconia industrial layout include Saint-Gobain, Japan’s Tosoh, Japan’s First Element, Showa Denko, France’s Suvi, and Japan’s Sumitomo Osaka Cement. Among them, the main business of First Element is zirconium-based, and most of the other companies are large-scale integrated enterprises.

With zirconia as the main component, after adding rare earth elements (mainly cerium oxide) and other oxides, composite zirconia powders with different performance characteristics can be formed. The nature of the composite zirconia depends on the type of material or crystal structure with which it is combined. Depending on the specific needs of the application, different formulations of composite zirconia materials with different properties can be prepared using different formulations.

In general, zirconia ceramics are divided into three categories: PSZ partially stabilized zirconia, also known as ceramic steel (with superior impact resistance); TZP tetragonal polycrystalline zirconia (better mechanical strength and fracture toughness); FSZ fully stabilized zirconia, crystalline phase cubic phase, with high-temperature conductivity, but high thermal expansion coefficient and poor thermal shock resistance.

Catalyst

Since zirconia is the only metal oxide that has both acidic and basic and oxidizing and reducing properties and is also a p-type semiconductor, it is easy to generate oxygen vacancies. As a catalyst carrier, it can interact with the active component, so its supported catalyst has more excellent properties than other materials-supported catalysts.

Precise ceramic parts

Zirconia ceramics can have excellent mechanical properties and fracture toughness, chemical resistance, and biocompatibility, so you can see the back of zirconia ceramic materials in industry and life.

Battery material

Solid oxide fuel cells (SOFC) are a new type of green energy that developed rapidly in the 1980s. Due to its high energy conversion efficiency (up to 65%) and the use of various fuels such as hydrogen, carbon monoxide, methane, etc., the system design is simple, and the pollution-free emission is low, which will be applied to the power generation system. The solid electrolyte is the core component of SOFC.

Zirconium oxide ceramics have become the most researched and widely used solid electrolyte materials because of their high ionic conductivity, good chemical stability, and structural stability.

Refractory

Zirconium oxide is an excellent special oxide refractory material and used at a high temperature (2300 ℃ – 2400 ℃). It has good chemical stability and is not easy to decompose, and is highly corrosive and resistant to acid and alkali slag. The industry uses zirconia-based refractories to produce refractory materials with excellent thermal shock resistance, corrosion resistance and wears resistance, which can make refractories have better performance and longer service life. It has been applied to the manufacturing process of industrial continuous casting steel and alloy materials and has important significance for improving the quality and cost of metal materials such as steel.

Optical material

Zirconium dioxide ZrO2 is a high refractive index, low absorptive material that can be used in coatings in the near-ultraviolet (<300 nm) to infrared (~8 μm) spectral regions. Nano-zirconia is added to the special coating material to increase the refractive index of the coating without changing the light transmittance. In the field of optical materials, in addition to being used as a coating, nano zirconia can also be used as a polishing material for optical lenses.

Electronic materials

For engines that use three-way catalytic converters to reduce pollution emissions, oxygen sensors are essential in the automotive industry. It uses the ceramic sensitive component to measure the oxygen potential in the exhaust pipe of the automobile, and calculates the corresponding oxygen concentration by the principle of chemical balance, and achieves the measuring component that monitors and controls the combustion air-fuel ratio to ensure the product quality and the exhaust gas emission standard. There are two types of oxygen sensors currently in use: titanium oxide and zirconium oxide. The core component is a porous zirconia ceramic tube, which is a solid electrolyte with sintered porous platinum (Pt) electrodes on both sides.

Plumbum zirconate titanate (PbZrxTi1-xO3, PZT) ceramics are a commercially important class of piezoelectric materials. Compared with other piezoelectric ceramics, PZT ceramics not only have high Curie temperature and piezoelectric coefficient, but also are easy to be doped and modified, and have good stability, so they have an important position in the electronic machinery manufacturing industry. They are the basic material for the preparation of most electromechanical devices such as sonar, hydrophone, ultrasonic generator, volt generator, and position trimmer.

Brake material

Ceramic materials have high heat resistance, thermal stability, and hardness. As an important member of advanced ceramics, zirconia ceramics certainly have similar characteristics. In view of the excellent quality of advanced ceramics, researchers have introduced it into friction materials to obtain longer-lasting and more durable friction materials under the most extreme working conditions. Today, more and more composite formulations for brake pads and clutch linings contain ceramic materials.

Many ceramic materials can be added to the brake material, including the zirconia ceramics we introduce today, in addition to silicon carbide, alumina, silica, and magnesia

Thermal spray material

Using thermal spraying technology, the ceramic coating is deposited on the metal collective, and the characteristics of high-temperature resistance, heat insulation, wear resistance, corrosion resistance and insulation of the ceramic are combined with the toughness, workability, the electrical and thermal conductivity of the metal material. The ideal composite coating product has become an important development direction in the field of composite materials and product development.

Aviation surface protection technology is a hotspot of thermal spraying for many years. The key components of aero-engines are high-temperature alloy turbine blades and turbine disks. The current engine turbine inlet temperature is close to or exceeds the melting point of the alloy, and such high temperatures will affect the function of the engine and dye. Therefore, an important development trend of superalloys is to coat the surface of the alloy with a high-melting ceramic coating (Thermal Barrier Coatings – TBCS) with good thermal insulation properties. At present, the most widely used TBCS is yttria-stabilized zirconia materials.

Stanford Advanced Materials supplies high-quality zirconium products to meet our customers’ R&D and production needs. Please visit http://www.samaterials.com for more information.

Application of Zirconia Electrolyte in Oxygen Sensor

With the gradual improvement of people’s awareness of environmental protection and energy conservation, many large and medium-sized enterprises, such as iron and steel metallurgy, petrochemical industry, thermal power plants, etc., have taken improving combustion efficiency, reduced energy consumption, reduced pollutant emissions, protecting the environment as an important way to improve product quality and enhance enterprise competitiveness.

Generally speaking, the direct way to improve the combustion efficiency is to continuously monitor the composition of flue gas in the flue gas analysis instrument (such as a flue gas analyzer, combustion efficiency tester, zirconia oxygen content detector), then analyze O2 content and CO content in flue gas, adjust the flow rate of combustion air and fuel, and determine better air consumption coefficient. Therefore, as an industrial tool to improve combustion efficiency, the oxygen sensors’ response time and measurement accuracy become key performance indicators. Due to its simple structure, short response time, wide measurement range (from PPM to percentage), high operating temperature (600℃-1200℃) and small maintenance, zirconia oxygen sensor has been widely used in metallurgy, chemical industry, electric power, automobile, and other fields.

Principle of zirconia sensor

The figure below is the schematic diagram of oxygen measurement with an oxygen probe. Porous platinum (Pt) electrodes were sintered on the two sides of the zirconia electrolyte (usually a zirconia tube). At a certain temperature, when the oxygen concentration on both sides of the electrolyte is different, the oxygen molecules on the high concentration side (air) are adsorbed on the platinum electrode and combine with electrons to form oxygen ions, making the electrode positively charged. The oxygen ions then migrate through the oxygen ion vacancy in the electrolyte to the Pt electrode on the low oxygen concentration side, releasing electrons and transforming them into oxygen molecules, making the electrode negatively charged.

This creates a certain electromotive force between the two electrodes. The zirconia electrolyte, the platinum electrode, and the gas with different oxygen concentrations on both sides constitute the oxygen probe, which is called the zirconia concentration difference cell. Then, by measuring the gas temperature and the output electromotive force, the oxygen partial pressure (concentration) can be calculated by the nengest equation, which is the basic detection principle of the zirconia oxygen sensor.

Common types of zirconia oxygen sensors

At present, the commonly used zirconia oxygen sensor includes a detection probe and direct insertion oxygen probe.

Detector probe

The sampling method is to introduce the measured gas into zirconia through a guide tube and then heat the zirconia to the working temperature (above 750℃) through a heating element. Zirconia is typically tubular and the electrode is porous platinum. Its advantage is that it is not affected by the temperature of the gas detected, and the oxygen content of the gas can be detected by using different flow guides at different temperatures.

This flexibility is used in much industrial on-line detection. Its disadvantages are slow response; the structure is complex and easy to affect the detection accuracy; when there are many impurities in the measured gas, the sampling tube is easy to be blocked; the porous platinum electrode is easy to be corroded by sulfur and arsenic or blocked by fine dust, etc. When the temperature of the detected gas is low (0-650℃), or when the measured gas is clean, it is suitable to use this detection method, such as oxygen measurement by nitrogen production machine and laboratory.

Direct probe

The direct insertion method is to directly insert zirconia into the gas measured at high temperature and directly detect the oxygen content in the gas. It uses the high temperature of the measured gas to bring zirconia to its operating temperature without the need for additional heaters.

The key technology of the direct insertion oxygen probe is the high-temperature sealing of ceramic material and the electrode. Due to the need to insert zirconia directly into the detection gas, the length of the oxygen probe is required to be relatively high. The effective length is about 500mm ~ 1000mm, and the special environment length is up to 1500mm, as well as high requirements for detection accuracy, working stability and service life. Therefore, it is difficult to adopt the whole zirconia tubular structure of the traditional zirconia oxygen probe with a direct insert oxygen probe, and the zirconia and alumina tube connection structure with high technical requirements is mostly adopted. The sealing performance is one of the most important technologies for the zirconia oxygen probe. Currently, the most advanced connection mode in the world is the permanent welding of zirconia and alumina tubes together.

Compared with the method of sampling pattern detection, the direct insertion method has obvious advantages: zirconia directly contacts with gas; high detection accuracy; fast reaction speed and small maintenance.

Brief summary

The regulation of oxygen content is a powerful means to monitor combustion conditions and improve combustion efficiency, and the accuracy and time of the measurement of the sensor have put forward certain requirements. Zirconia, as a solid electrolyte, is used to transport conductive ions in oxygen sensors. At present, there are two kinds of zirconia oxygen sensors: detection type and direct insertion type. The direct insertion type probes are widely used because of their direct contact with the measured gas, high measurement accuracy and fast reaction time.

Stanford Advanced Materials supplies high-quality zirconia products to meet our customers’ R&D and production needs. Please visit https://www.samaterials.com/ for more information.

Why Does Zirconium Explode? How to Solve It?

Zirconium (Zr) is estimated to make up about 0.017% of the lithosphere. Because zirconium is chemically active at temperatures only slightly above normal atmospheric temperatures, it exists only in a bound state. The most common ores are zircon (ZrO2) and barium lead (ZrSiO4).

The hafnium (Hf) coexists with zirconium in all its terrestrial ores. The content of hafnium fluctuates greatly, accounting for 2% (the total amount of hafnium and zirconium). The two elements are chemically closer than any other in the periodic table, and the similarities are so great that no difference in mass has been found to separate them.

Zircon

Zircon has been considered a gem since ancient times because it is usually found in large single crystals. However, most commercial deposits of zirconium ore are in beach sand, where the relatively heavy and chemically inert zirconium minerals are retained, while the lighter parts are broken down and washed away by water. India, Malaya, Australia and the United States are known to have large deposits of this sand. Harmful substances have been found in commercially useful deposits, first in Brazil and later in other places, including Sweden, India, and Italy, while some zirconium ores are also commercially mined in Madagascar, Nigeria, Senegal, and South Africa.

Zircon is used as a component of foundry sand, abrasive, and laboratory crucible zircon and zirconia refractories. It is found in ceramic compositions and acts as an emulsifier in glazes and enamels. Zirconium and zirconia bricks are used as glass linings, zirconia templates are also used for extrusion iron and non-ferrous metal molds and injection metal nozzle linings, especially for continuous casting.

Zirconium metal

More than 90% of zirconium is now used in nuclear power generation because zirconium has a low neutron absorption cross-section and is highly resistant to corrosion in atomic reactors, provided it contains no hafnium. In addition, zirconium is used in the manufacture of cast iron, steel, and surgical instruments, as well as in arc lamps, fireworks, special solder, plastic pigments, etc.

The powdered zirconium metal is used as a “getter” in thermionic tubes that absorb traces of residual gas after it has been drained and expelled. The metal, in the form of filaments or wool, is also used as a filter for camera flashes. Block metals can be used in the lining of reaction vessels, either pure or alloyed. It is also used as lining for pumps and piping systems in chemical processes. Excellent zirconium and niobium superconducting alloys are used in the magnetic field of 6.7T.

Zirconium compounds

Zirconium carbide and zirconium diboride are hard, refractory, metallic compounds that have been used in metal cutting tools. Diboride is also used as the shell of open-hearth thermocouples with long life. Zirconium tetrachloride is used in organic synthesis and water repellent in textiles, and it is also useful as a tanning agent.

The metal hafnium has been used as a coating for the tantalum components of rocket engines, which must work at very high temperatures and under corrosive conditions. Because of its high thermal cross-section, it is also used as a control rod material in nuclear reactors. In addition, hafnium is used in the manufacture of electrodes and filament bulbs.

The harm of zirconium

It is not accurate to say that zirconium compounds are physiologically inert, but most organisms seem to tolerate zirconium quite well compared to most heavy metals. Zirconium salts have been used to treat plutonium poisoning to replace the deposition of plutonium (and yttrium) in the skeleton and to prevent precipitation when early processing begins.

Some studies have shown that more than 20% of zirconia can be absorbed in rats for a long time without harmful effects. LD50 of rats injected with sodium zirconium citrate is about 171mg/kg. Other investigators found an intraperitoneal injection of LD50 rats with zirconium lactate 670mg/kg, barium zirconium 420mg/kg, and mice with sodium zirconium lactate 51mg/kg.

Zirconium compounds have been recommended for topical treatment of suede dermatitis and body deodorants, among which are zirconia carbide hydrate, zirconia hydrate, and sodium zirconium lactate. There have been some reports of persistent granulomas on the skin as a result of these applications.

More immediate interest in occupational exposure is the effect of inhaled zirconium compounds, which have not been studied as extensively as other approaches to drug administration. However, there are several experiments and at least one report on human exposure. In this case, a chemical engineer who had been at a zirconium and hafnium processing plant for seven years was found to have granulomatous lung disease. As no similar damage was found on all other employees, it was concluded that the situation was most likely due to relatively high levels of beryllium prior to zirconium contact.

Animal exposure to zirconium compounds has shown that severe persistent chronic interstitial pneumonia occurs in both zirconium lactate and barium zirconium at atmospheric concentrations of about 5mg/m3. Short exposure to sodium zirconium lactate at a higher air concentration of 4900mg/m3 resulted in peribronchoabscess, peribronchogranuloma, and lobular pneumonia. Despite the lack of literature on human zirconia pneumoconiosis, the authors of one study suggest that zirconium should be considered as a possible cause of pneumoconiosis and recommend appropriate precautions in the workplace.

A small number of studies on the toxicity of hafnium compounds indicate that their acute toxicity is slightly higher than that of zirconium salts. Like soluble zirconium salts, hafnium chloride-induced cardiovascular failure and respiratory arrest in cats at 10mg/kg.

Safety and health measures

Zirconium is burned as a fine powder in air, nitrogen or carbon dioxide. The spontaneous air explosion of these powders at concentrations of 45,000 to 300,000 mg/m3 may be caused by static electricity generated by the separation of the disturbed particles.
Metal powders should be transported and treated in a wet state; water is usually used for wetting. When the powder is dried before use, the amount used should be as small as possible and should be operated in a separate compartment to prevent the spread of the explosion.
All ignition sources including electrostatic charges should be eliminated. All surfaces in the area should be impermeable and seamless so that they can be washed down with water and completely free from dust. Any spilled powder should be washed with water immediately so that it has no chance to dry. Old paper and cloth contaminated with powder should be kept moist in a covered container until they are removed and burned, at least daily.
Dry powders should be treated with as little interference as possible, and then only sparkless tools should be used. Rubber or plastic aprons, if worn on overalls, should be treated with antistatic compounds. Work clothes shall be made of non-synthetic fibers unless effectively treated with antistatic materials.
All processes using zirconium and hafnium should be designed and ventilated to keep air pollution below exposure limits.

Stanford Advanced Materials supplies high-quality zirconium products to meet our customers’ R&D and production needs. Please visit https://www.samaterials.com/ for more information.

Applications of Zirconia in Structural And Functional Ceramics

Zirconia is a kind of inorganic nonmetallic material with high-temperature resistance, corrosion resistance, abrasion resistance, and excellent electrical conductivity. Since the mid-1970s, developed countries have invested heavily in the research and development of zirconia products, extending the application field of zirconia to structural and functional materials. Zirconia is also one of the new high-performance materials in the national industrial policy, which is widely used in various industries.

Applications of zirconia in structural ceramics

In 1975, R.G.Garvie, Australia, prepared partially stabilized zirconia with calcium oxide as a stabilizer, and improved the toughness and strength of zirconia for the first time, which greatly expanded its application in the field of structural ceramics.

1. Zirconia ceramic bearings

Zirconia ceramic bearing has the characteristics of wear resistance, corrosion resistance, high-temperature resistance, high cold resistance, oil-free self-lubrication, resistance to magnetoelectric insulation, etc. It can be used in an extremely harsh environment and under special working conditions.

Zirconia ceramic bearings have been used in micro cooling fans, and the product life and noise stability are better than traditional ball and sliding bearing systems. Foxconn is the first company to use zirconia ceramic bearings in computer cooling fans.

2. Zirconia ceramic valve

At present, valves commonly used in various industries are made of metal materials. Due to the limitation of metal material itself, the corrosion damage of metal has a considerable impact on the working life, reliability and service life of valve wear resistance.

The working climate of the valve pipeline is very complicated. Hydrogen sulfide, carbon dioxide, and some organic acids in oil, gas, and reservoir water increase the destructive power of their surfaces, rapidly disabling them. Zirconia ceramic valve has excellent wear resistance, corrosion resistance, high-temperature resistance, and thermal shock resistance, so it is suitable for this field.

3. Zirconia abrasive material

Zirconia ball has the advantages of high hardness, low wear rate and long service life, which can greatly reduce the pollution of grinding materials and ensure the quality of products. Besides that, zirconia material has high density and strong impact energy when used as a grinding medium, which can greatly improve the grinding dispersion efficiency. Good chemical stability determines its corrosion resistance and can be used in acidic and alkaline media.

Applications of zirconia in functional ceramics

1. Zirconia ceramic knives

Zirconia ceramic knife has the characteristics of high strength, wear resistance, no rust, no oxidation, acid and alkali resistance, anti-static, and no reaction with the food. Its body is as shiny as jade, which also makes it an ideal high-tech green knife. At present, the main products on the market are zirconia ceramic knife, scissors, razor, scalpel and so on, which has become popular in Europe, America, and Japan in recent years.

2. Zirconia high-temperature heating element

Zirconia is an insulating material at room temperature, its resistivity is as high as 1015 Ω cm, and it can conduct electricity when the temperature to 600 ℃. When the temperature reaches 1000℃ above, it is a good conductor and can be used as 1800℃ high-temperature heating element, with the highest operating temperature of 2400℃. At present, zirconia has been successfully used in heating elements and equipment with an oxidation atmosphere above 2000℃.

3. Zirconia bioceramics

The quality of ceramic tooth material directly affects its quality and patients’ health. The inner crown of porcelain teeth is made of different metal materials, which is easy to oxidize with saliva. Since there is no metal inner canopy, zirconia ceramic teeth have good transparency, excellent gloss, and effectively avoid tooth allergies and gum black lines.

4. Zirconia coating material

Zirconia thermal barrier ceramic coating material with a high-performance stabilizer such as yttrium oxide (Y2O3) is mainly used in high-performance turbine aero-engine. The thermal barrier coating uses ceramic insulation and corrosion resistance to protect the metal material, which can not only improve the fuel combustion efficiency but also greatly extend the life of the engine. Thermal barrier coating has important application value in aviation, aerospace, surface ships, large thermal power generation, and automobile power, etc. It is one of the most important technologies in modern national defense.

5. Zirconia oxygen sensor

Oxygen sensors are essential in the automotive industry for engines that use three-way catalytic converters to reduce pollution emissions. Currently, there are two kinds of oxygen sensors in use: titanium oxide and zirconia. Japanese scientists made a porous oxygen sensor out of zirconia, which is installed in an engine to automatically detect the ratio of oxygen to combustion gas in the engine, and automatically control the ratio of input gas and output gas, thus greatly reducing the harmful gas emissions from cars.

Stanford Advanced Materials supplies high-quality zirconia ceramic products to meet our customers’ R&D and production needs. Please visit https://www.samaterials.com for more information.