Zirconium Metal – Page 13 – Provide you with various industry information about zirconium

Zirconium-containing Materials Used in the Refractories

As a new material, zirconium-containing material has been developed rapidly in the recent ten years. In the field of refractories, natural zirconium-containing mineral raw materials and artificial extraction or synthesis of zirconium oxide and composite oxide raw materials have also been widely used to produce a variety of excellent zirconium-containing refractories.

There are about 50 kinds of zirconium minerals known to us, among which more than 20 are common. Zirconium mineral raw materials for industrial use are mainly zirconium quartz, oblique zircon, hafnium zircon, and anisotropic zircon. With the development of science and technology, zirconium oxides and composite oxides have been extracted or synthesized by various processing methods and applied in various fields.

Zirconium-containing raw materials are widely used in the refractory industry, which is mainly because of their high melting temperature and strong chemical stability. They have good corrosion resistance to metal melt, slag, or glass fluid, as well as good thermal shock resistance, so they can be used as refractories for glass kiln, metallurgical industry refractories, and so on.

Zirconium-containing refractories are mainly used in the melting part, superstructure, side wall, and fluid hole of glass melting furnace. Refractories made from zirconium materials are widely used in the metallurgical industry and can be divided into zirconium quartz products, zirconia products, aluminum zirconia carbon products, zirconium carbon products, calcium zirconate products, zirconium boride products, zirconia modified refractories, etc.

Zirconium quartz products have the characteristics of high-temperature resistance, good resistance to acid slag, small erosion, slight viscosity of slag, small thermal expansion coefficient, good thermal shock stability, etc., which can be better used as the lining of steel drums, but also can be masonry in the direct impact of steel, slag line parts, around the nozzle and other key parts.

The main raw material for the production of zirconium quartz products is zirconium quartz concentrate, and some clay, pyrophyllite, chromium oxide, and zirconia can be also added as needed. In general, zirconium particles are small in size and are not suitable for direct brick production, which requires the raw materials of zirconium quartz and part of the combined clay to be mixed, semi-dry pressed, and made into the blank. There are a wide variety of zirconia products and many molding methods, such as mud pouring method, hot pressing method, machine pressing method, isostatic pressure method, etc.

Aluminum-zirconium carbonaceous product is developed on the basis of aluminum-carbonaceous product, and it can be used as sliding nozzle brick of ladle (or tundish), long nozzle, plug rod, immersed nozzle, and so on. Compared with the corresponding aluminum carbon material, aluminum zirconium carbon products have better oxidation resistance, thermal shock stability, erosion resistance, and higher strength, so the service life is longer. The addition of a certain amount of zirconia in refractory materials such as jade-quality, high-alumina, magnesium-calcium, aluminum-magnesium, magnesium-chromium and magnesium-carbon commonly used in the metallurgical industry can improve the chemical stability, thermal shock stability and strength of these materials. In these materials, zirconia is usually introduced in the form of zircon sand and zirconia.

The specific production process is usually the same or slightly changed before modification. Generally speaking, zirconium-containing raw materials have been widely used in the field of refractories due to their excellent properties, and their application scope will be more and more extensive.

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An Overview of Colored Zirconia Ceramics

Zirconia ceramics, with high strength, high toughness, wear resistance, corrosion resistance and other excellent properties, are widely used in mold, tools, ceramic bearings, electronic components, biomedical materials, and other fields. At present, with the wide application of zirconia ceramics in the field of electronic products, especially as the backboard of mobile phones, its single color has restricted its application and cannot meet people’s requirements on the appearance of structural devices. Therefore, the development of rich colors can greatly expand the application of zirconia ceramic materials in the field, which has broad prospects for development.

Overview of colored zirconia ceramics

With the development of technology, the synthesis methods of colored zirconia ceramics are becoming more and more diversified. The key to its preparation technology is that the color phase (such as CoO, Cr2O3, Fe2O3, etc.) can be evenly distributed in the ceramic matrix. The color zirconia ceramics must have a stable crystal structure, bright and uniform color, high temperature and good chemical stability without damaging its inherent properties.

For colored zirconia ceramics, the capillary force, electrostatic attraction and van der Waals force between particles are prominent due to the small size, large surface area and high surface energy of the particles forming the matrix and colorizing phase. In this environment, nano-powder particles are easily agglomerated into a larger particle body, which leads to a significant decrease in the relatively good physical and chemical properties of nano-complex phase ceramics. Therefore, the agglomeration phenomenon must be overcome to prepare zirconia ceramics with good properties and diverse colors, so that the color phase is evenly dispersed in the ceramic matrix material.

Preparation of colored zirconia ceramics

The preparation methods of color zirconia ceramics mainly include solid phase mixing, chemical co-precipitation, liquid phase impregnation, and high-temperature carburization.

Solid-phase mixing

Color zirconia powders were prepared by solid-phase mixing with ball milling technology. It mixes oxide particles such as the colorant and mineralization agent with stable zirconia nanometer powder in a certain chemical proportion and grinds them into balls. Solid particles are refined in this process, resulting in micro-cracks, lattice distortion, and surface energy increase that are conducive to the realization of the low-temperature chemical reaction.

Chemical co-precipitation

After the solution of a zirconium salt, stabilizer salt and colorant ion salt is mixed, hydroxide or carbonate precipitation is generated by the reaction with alkali or carbonate, and then the zirconia composite powder is obtained by heating and decomposition. In coprecipitation, metal cations in a solution precipitate together to form a mixture due to an excess of precipitants. Under special circumstances, the composite oxides or their precursors that are required to be deposited must conform to a certain stoichiometric ratio, and cations are required to generate precipitation in a certain proportion.

Liquid phase impregnation

Liquid phase impregnation will firstly extract and degrease zirconia ceramic blank with connected pore structure after injection molding and then place it in a solution containing chromophore ions for impregnation. The colorized ions infiltrate into the surface of the billet through the pores of the solution, and the depth of infiltration is controlled by the length of infiltration time. In addition, the blank body obtained by water extraction and degreasing is directly used for infiltration, because the blank body after water extraction and degreasing will form a uniformly connected void structure, which facilitates the uniform distribution of chromophore ions in the blank body. Uniform color zirconia ceramics can be prepared only if they can be soaked completely.

High temperature carburizing/nitrogen

High-temperature carburizing is mainly used to prepare black zirconia ceramics. The technological process is to process zirconia ceramic into a blank, normal degreasing, dewaxing, at low temperature without protective atmosphere element burning treatment, and then the processed zirconia green blank under vacuum protection conditions for high-temperature sintering. Graphite crucible is used to place the workpiece during sintering, and graphite paper is placed on the workpiece surface. The black coloring of zirconia ceramics was realized by graphite infiltration into the zirconia surface at high temperatures.

Applications of color zirconia ceramics

The backplate of a mobile phone

Zirconia ceramic used in mobile phone backplate has no interference, no magnetic, strong reception signal, as well as color diversity, besides, it can also be used for fingerprint identification module ceramic cover plate.

Smart wearable appearance parts

Zirconia ceramic material has the advantages of scratch resistance, scratch resistance, no shielding, warm and moist hand texture, good corrosion resistance and bio-compatibility. It is applied to intelligent wearable appearance parts.

Ceramic knives

Zirconia ceramic knives have excellent characteristics such as ultra-high strength, abrasion resistance, sharp edge, no rust, no odor, and durability.

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Main Factors that Affect the Performance of Ceramics

The main raw material of zirconia ceramics is high purity zirconia powder, and its performance and content have a great impact on zirconia ceramics. Besides that, the properties of zirconia ceramics are affected by other factors. In order to prepare high-performance zirconia ceramics, we should control the main influencing factors, including raw material size, molding method, and sintering.

Forming method

Zirconia ceramics with low porosity and high density have excellent jointing properties. High density means that the grains in the ceramic body are closely arranged, and it is not easy to form a destructive breakthrough point when subjected to external loads or corrosive substances.

The forming method is the key to obtaining the calcium density of the ceramic embryo body. Zirconia ceramics are usually formed by means of dry pressing, isostatic pressing, and hot die-casting. Different methods have different characteristics and have different effects on sintering properties as well as the microstructure of curing rate ceramics. Generally, grouting and hot die-casting are the main technologies for products with complex shapes, while dry compression molding can be adopted for products with simple shapes. Generally speaking, the density of dry-pressed products is better than that of hot-die-cast products.

The particle size of the raw material

The particle size of raw material has a great influence on the properties of products. Only when the raw material is fine enough can the final finished product be fired into a microstructure, which makes it have good wear resistance. The finer the zirconia powder particles are, the more active they are and the sintering can be promoted.

Due to the difference between corundum and glass phase linear expansion coefficient, the stress concentration at the grain boundary can reduce the risk of cracking. The fine grain can also hinder the development of micro-cracks, and it is not easy to break into transgranular, which is conducive to improving fracture toughness and abrasion resistance.

Sintering

Sintering of ceramic is the densification process of raw ceramic at high temperatures. With the increase in temperature and time, the adhesion between powder particles and the strength of sintered body increase, the aggregation of powder particles becomes a strong polycrystalline sintered body with a certain microstructure, and the required physical/mechanical properties of products or materials are obtained. The densification rate and the final structure of the sample often reflect what kind of heat treatment process it has gone through.

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Argon Arc Welding Technology of Zirconium and Zirconium Alloy

Zirconium and zirconium alloys have excellent corrosion resistance to acid and alkali, and even surpass niobium, titanium and other metals in some media. Therefore, zirconium and zirconium alloys are gradually used as structural materials such as equipment and pipelines in the chemical industry with strong corrosion resistance due to their good corrosion resistance in recent years.

Due to the high-temperature chemical activity, zirconium and zirconium alloys can react with various elements in the air at high temperature, thus damaging their mechanical properties. Therefore, in the process of zirconium and zirconium alloy welding, the key to ensuring the quality of welding is to select a clean operating environment and strengthen the isolation and protection of welding seams and parts in the heat-affected zone.

Basic properties of zirconium and zirconium alloys

Zirconium and zirconium alloy materials mainly include R60702, R60704, and R60705. Zirconium and zirconium alloys have good welding properties and stable chemical properties at room temperature. However, its high-temperature chemical properties are very active, and it has a strong affinity for the pollution of oxygen, nitrogen, hydrogen and dust and humidity in the operating environment.

The excellent corrosion resistance of zirconium and zirconium alloys comes from the oxide film formed on the surface and depends on the integrity and firmness of the oxide film. When zirconium and zirconium alloy absorb a certain amount of oxygen, nitrogen, hydrogen, and other gas impurities, their mechanical properties and corrosion resistance will decrease sharply. Therefore, strengthening the protection of the surface of environmental dust, humidity and heat affected area and the back of the welding seam is the key element of quality control in the welding process.

Factors influencing the welding quality of zirconium and zirconium alloy

The tendency of weld cracks

Due to the low thermal expansion coefficient of zirconium and zirconium alloy, the volume change caused by thermal deformation and phase change is very small, and the content of sulfur, phosphorus, carbon and other impurities is very low, there is no obvious trend of cracks in the welding process. However, when the welding seam absorbs a certain amount of oxygen, nitrogen and hydrogen gas impurities, the performance of the welding seam and the heat-affected zone will become brittle. If there is stress in the welding seam, cold cracks will occur.

At the same time, hydrogen atoms have the property of diffusing and aggregating to the high-stress parts in the heat-affected zone with lower temperature, which leads to the formation of relatively weak links in these parts, which may lead to the generation of welding delay cracks.

Selection of welding materials

The filler wire for zirconium and zirconium alloy welding should be selected according to the principle of matching the base material composition. The surface of welding wire shall not have heavy skin, crack, the oxidation phenomenon and metal or non-metal inclusion defects. Besides, the welding wire should be cleaned and dried before use.

Selection of protective gas

Argon arc welding with tungsten electrode of zirconium and zirconium alloy shall adopt high purity argon with 99.999% purity and the impurity content shall meet the requirements of GB/T4842 current standards.

Due to the extremely high requirements on the purity of welding protective gas, continuous gas charging is required during the welding process, and the gas cannot be interrupted in the process; otherwise, argon charging needs to be replaced again. Therefore, the direct gas supply method using ordinary argon in a single bottle cannot meet the protection requirements. It is necessary to increase the gas supply capacity of multiple argon bottles in series and satisfy the simultaneous operation of multiple welders through the air separation cylinder.

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7 Methods to Toughen the Zirconia Ceramics

Zirconia ceramics are characterized by unique physical and chemical properties such as high hardness, low thermal conductivity, high melting point, resistance to high temperature and corrosion, chemical inertia and amphoteric properties. As a special ceramic material, zirconia has a broad application prospect in electronics, aerospace, aviation, and nuclear industries.

At present, the toughening methods of ceramics mainly include phase transformation toughening, particle toughening, fiber toughening, self-toughening, diffusion toughening, co-toughening and nano toughening.

Phase transformation toughening

The toughening of the phase transition refers to a phase transition of t-ZrO2 of the metastable quadrilateral phase under the stress field at the crack tip, then the compressive stress is formed on the crack, which hinders the crack growth and plays a role of toughening.

Besides, external conditions (such as laser shock, fatigue fracture toughness, low temperature, grain size and content, critical transformation energy, etc.) have great influence on the toughening of zirconia ceramics. If the stress and volume produced by the phase transition are large, the product is prone to fracture. Therefore, the influence of external factors on the toughening of zirconia ceramics should be avoided in the production process.

Particles toughening

Particle toughening refers to adding ZrO2 ceramic powder as a toughening agent. Although the effect is not as good as whisker and fiber, there is still a certain toughening effect if the type, size, content and matrix materials are selected properly. The advantages of particle toughening are simple and feasible, and the toughening will bring about the improvement of high-temperature strength and high-temperature creep property. The toughening mechanism of particle toughening mainly includes grain refinement and crack turning to the bifurcation.

Fibre toughening

The toughening principle of fiber and whisker is that the closed stress is applied to the crack surface due to the deformation of crystal close to the crack tip, the external stress of the crack tip is offset, and the passivating crack growth is achieved, so as to play a toughening role. In addition, when the crack grows, the pulling out of the column crystal also overcomes the friction force, which also plays a role in toughening.

The self-toughening

Due to the existence of columnar crystals, the fracture process of zirconia ceramics can cause the crack to deflect, change and increase the crack growth path, thus passivating the crack to increase the crack growth resistance, thus achieving the purpose of toughening.

Dispersion toughening

Diffusion toughening mainly refers to the toughening of tetragonal ZrO2 particles to ceramic matrix. Besides the phase change toughening mechanism, there is also the diffusion toughening mechanism of the second phase particle. Before the crack propagation, the internal residual strain energy of the ceramics must be overcome, so as to achieve the purpose of toughening.

Microcrack toughening

Microcrack toughening refers to adding ductile materials to the stress tip of the crack to generate microcracks to disperse the stress, reduce the force of the crack forward, and thus increase the toughness of the material. When phase transition occurs, residual strain energy effects and microcracks often occur. Therefore, the effect of phase transition and toughening is remarkable.

Composite toughening

Composite toughening refers to the application of several toughening mechanisms in the actual toughening process of ZrO2 ceramics, so as to improve the toughening effect of ZrO2 ceramics. In the practical application process, the specific toughening mechanism is selected according to the different properties of zirconia ceramic materials to be prepared.

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Zirconia Ceramic Structural Parts VS Auto Parts

As we all know, a car is a product with an extremely demanding operating environment and working conditions, so the various components that make up this giant must have very superior functions. The zirconia ceramic structure has been widely used in auto parts.

Zirconia ceramic structure parts with excellent performance just make up for the lack of metal materials, so they began to be accepted by the automobile. For example, it has a long vibration tolerance of 20 grams; as parts used in combustion and exhaust systems, it can endure 50 ~ 60 ℃/S of thermal shock for a long time; due to the strong mechanical reliability of the zirconia ceramic, the failure rate is usually between 10 and 5; it can also be mass-produced and low in price, which is convenient for the formation of industrial management.

In recent years, scientists in the international special ceramics field have developed a large number of automobile special ceramics through hard research, and experiments and industrial applications have proved that the superior mechanical properties and high-temperature chemical properties of ceramic materials have far surpassed those of metal materials or other materials. At present, the applications of zirconia ceramic structure parts in auto parts industry are as follows.

Zirconia ceramic oxygen sensor

The zirconia ceramic oxygen sensor has high mechanical properties and reliability. As a component of clean exhaust, O2 concentration in automobile exhaust is measured, and the measured value is fed back to the gas and fuel supply system of the engine to keep the fuel always in full combustion state. Since all phases of the ceramic material are partially stabilized zirconia mixed with fully cubic, tetragonal and monoclinic crystals, the mechanical properties are superior during use and the heat generated by friction can be reduced.

Zirconia ceramic valve heater

In order to make the engine burn completely when starting, a heating device, the valve heater, is installed on the suction side of the engine, which is used to heat the air so that the fuel vaporizes and mixes completely. In order to control the temperature and improve the reliability of the device, the barium titanate ceramic PTC (thermistor) is used as the valve heater. After adopting the ceramic valve heater, the engine is in full combustion state when it starts, so as to improve thermal efficiency, energy saving, and purification and exhaust efficiency.

Zirconia ceramic engine

The application of special ceramics in the automobile has been popularized by the piston engine, and there will also be an auxiliary combustion chamber, piston head, cylinder liner, cylinder head, pressurized rotor, etc. Special ceramic materials such as silicon nitride, silicon carbide, and partially stabilized zirconia are also being considered for these parts.

Zirconia ceramic sensor

The shock absorber of the high-class car is a smart shock absorber that is developed by using the positive piezoelectric effect, inverse piezoelectric effect and electrostrictive effect of sensitive ceramics. The smart shock absorber, with its ability to recognize and self-regulate the road, minimizes the vibration of cars on rough roads, making them comfortable for the passenger.

Intelligent ceramic wipers

The intelligent ceramic windshield wiper is made of barium titanate, which can automatically sense rainfall and adjust the windshield wiper to the best speed. Some other ceramic sensing elements, such as thermal, pressure, humidity and magnetic ceramic materials, can also be sensitive to temperature, humidity, condensation, anti-freezing, etc. with automatic control and adjustment.

In addition, many parts, and small devices used in automobiles are made of special ceramic materials, such as the electronic buzzer, ultrasonic vibrator, heat-absorbing glass, photocell, oil plug ring, oil seal, etc. These kinds of automobile products made of new special ceramic materials generally have high physical and chemical properties, such as anti-seismic, wear-resisting, anti-corrosion, high-temperature resistant, lightweight and easy to process and produce.

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Can Zirconia Ceramics be used as Wearables?

Zirconia ceramics enter the consumer electronics represented by mobile phones in three subdivisions.

The main application area is the back cover of the mobile phone, which is mainly used to upgrade and supplement plastic, glass and metal materials.
The second is the patch or the case of the wearable device used for fingerprint identification, which mainly benefits from the increase in the installed rate of the fingerprint reader and the replacement of sapphire.
Finally, it is used for small structural parts such as lock screen and volume button, which is a continuation of the ceramic button business in the era of the functional machine.

In contrast, zirconia has a density of 6 grams per cubic meter, the heaviest of all materials. Fortunately, zirconia ceramics can be controlled by thickness, keeping the total weight to a level lighter than glass. Besides, the back set of fine CNC processing required time and high cost because of the superior wear-resisting performance of ceramics. As a result, zirconia has exploded more quickly in areas such as fingerprint recognition, wearable devices and the back cover of mobile phones, where it is more cost-effective.

Apple Watch

As early as April 2015, the Apple Watch went on the market and used zirconia ceramic material as the rear cover appearance for the first time, which brings the wearables’ ceramic facade to a climax. Compared with metals and plastics, zirconia ceramics are wear-resistant and skin-friendly, making them more suitable for use on wearable devices. In addition, the airtightness and waterproof of wearable devices determine that most of them adopt wireless charging mode, and the ceramic material is used as the rear cover with small signal shielding, which is obviously superior to the metal material.

Due to the aesthetic and waterproof considerations, most wearable devices have the function of wireless charging, and the wireless charging scheme of the non-metal back shell is easier to design. From the perspective of shielding efficiency, zirconia ceramics, as a non-metal material, have no shielding effect on electromagnetic signals, and will not affect the internal antenna layout at all. Therefore, it can be conveniently shaped into a whole, instead of making an ugly segmented structure like aluminum magnesium alloy. Arguably, Apple’s Apple Watch led the trend of zirconia ceramics being the back cover of wearables.

Wearable devices

In addition, zirconia ceramics also have the following advantages as wearable devices. As mentioned above, zirconia ceramics have higher dielectric constants that make fingerprint scanners work more sensitively and cost significantly less than sapphires. The Mohs hardness of zirconia ceramics is around 8.5, which is very close to that of sapphire 9. Given all the advantages of zirconia ceramics, it is expected that it will become the preferred rear cover material in the field of wearable devices in the future.

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

How did people come up with Zirconia Ceramics for Tableware?

Most people think they are very strange to zirconia ceramics and have little contact with them, but in fact, we only need a few examples to make it clear. The simplest examples are the utensils we use in our daily lives, such as zirconia ceramic chopsticks, zirconia ceramic soup spoons, zirconia ceramic teacups, and so on, all of which are made from zirconia ceramics.

But how did people come up with this material for tableware? This is because traditional ceramics have problems such as poor resistance to fall and durability, and the appearance and application of zirconia ceramics completely solve these problems. This special material is not only resistant to acid, alkali, and rust, but also has good environmental protection. It is the ideal choice of tableware materials.

Zirconia ceramics are by far the most resilient of ceramic materials, so you don’t have to worry about breaking them when you make your cutlery. Besides, it has an excellent high-temperature solid electrolyte, oxygen ions can also pass through at a high temperature, which is a very special ceramic material. The following is a special case of zirconia ceramic knife to explain in detail the application of zirconia ceramics in kitchen utensils.

Zirconia ceramic knife is made from zirconia ceramic material which belongs to nonmetal material. Since the material purity and particle size were controlled, and various carbides, nitride, boride, and oxides were added to improve their properties, not only did the bending strength of the zirconia ceramic knife increase to 0.9~1.0GPa, but also the fracture toughness and impact resistance were greatly improved. In recent years, the application range of zirconia ceramic knives has been expanding, from high-tech fields such as aerospace to the industrial ceramic knife.

Characteristics of zirconia ceramic knife

Clean

The ceramic knife is designed in a close manner with no gaps and pores, no sticky bacteria and foreign body, and will not become a breeding ground for bacteria. The super antibacterial function of the ceramic knife is very suitable for cutting food which can be eaten directly.

Resistance to food oxidation

The ceramic knife will not react with any food, maintaining the original taste of the food, allowing you to fully experience the enjoyment of the delicious food. By the way, ceramic knives are very suitable for cutting raw fish, fruits, vegetables, boneless meat, and cooked food.

Healthy and Eco-friendly

The ceramic knife, which does not emit metal ions, has excellent non-metal properties, making it never rust. Besides, the healthy and environmentally friendly ceramic knives are resistant to various acid-base organics, and will not be corroded by acids and oils in fruits and vegetables. It is non-toxic, pollution-free, non-oxidizing and non-rusting.

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Is the Zirconia Full-porcelain Teeth Safe?

Zirconia is an excellent high-tech biological material with good biocompatibility that is superior to various metal alloys, including gold. Zirconia has no irritation or allergic reaction to the gingiva, and is suitable for oral application, avoiding allergic, stimulative, and corrosive reactions of metal in the oral cavity.

Excellent mechanical properties

The zirconia full porcelain dental material has a winding strength greater than 900MPa, so it can also be used to repair the posterior tooth and the all-ceramic bridge with more than 6 units.

Good biocompatibility

In the latest clinical evaluation report of CRAI, a U.S. clinical research association, it was found that the zirconia all-ceramic crown itself had no metal, and the restoration of the zirconia all-ceramic crown could exclude the metal allergic reaction and have good biocompatibility. Therefore, zirconia all-ceramic crowns are superior to various metal alloys in terms of biocompatibility, including gold materials.

Safe non-metallic materials

At present, zirconia is the only mineral in the natural world, which does not contain any metal, and it is safer after medical clean processing.

No obstruction to the X-Ray

If cranial X-ray, CT, and MRI examinations are needed after inserting the zirconia porcelain teeth, the dentures do not need to be removed in the future, because the zirconia porcelain teeth do not have any obstruction to X-ray, so a lot of trouble is avoided.

High intensity and density

Zirconia is widely used, especially in high-precision instruments, such as aviation equipment, because of its ultra-high-strength and density. Among them, the unique resistance to rupture and the strong firmness after rupture can be made into all-ceramic Bridges of more than 6 units, thus solving the problem that all all-ceramic systems cannot be long Bridges. Therefore, they are favored by doctors and patients.

Perfect color

Due to the white color of the base crown of structural ceramics, the neck will not become dark for a period of time after the insert, which solves the extremely difficult problem of the metal crown.

Healthy biomaterials

Zirconia is an excellent high-tech biological material with excellent biocompatibility and no irritation or allergic reactions to the gums. It is very suitable for the mouth.

PFM (porcelain fused to metal) is accepted by most patients for its good strength, but it has its fatal disadvantages. The metal base of low-end porcelain teeth is easy to oxidize and form gray oxides. When scattered and deposited at the edge of the gingiva, the gingiva will turn gray and affect its appearance. At the same time, it has a strong stimulation effect on the gingiva, and some patients may also have gingiva swelling, bleeding, allergy, and other symptoms, which is difficult to meet the clinical requirements. High-end metal porcelain teeth (gold alloy) are expensive without these drawbacks.

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How to tell the Zirconia from Diamonds?

Diamond is the product of adamas finishing, which is the hardest and simplest gemstone in the world. It is a natural crystal with a cubic structure made of carbon. The bigger the diamond, the rarer it is. Diamond often contains 0.05%-0.2% impurity elements, among which N and B are the most important. The pure diamond is colorless and transparent, which presents different colors due to the mixing of trace elements.

Natural diamonds are expensive due to their scarcity, especially the larger ones. However, artificial diamonds (synthetic diamonds) are difficult to achieve large size gemstones. Generally, synthetic diamonds are used in cutting and polishing tools. Therefore, in order to meet the design needs of jewelry and some products, there are usually some substitutes, such as glass, artificial spinel, artificial sapphire, zircon, scheelite, strontium titanate, cubic zirconia and so on. Among them, cubic zirconia is very close to diamond in terms of its optical and hardness properties and is the most common diamond substitute.

The cubic zirconia was first developed by the Soviets, also known as Soviet Stone. Cubic zirconia in cubic crystals is rare in nature and is usually synthesized artificially. Synthetic cubic zirconia is a hard, colorless and optically immaculate crystal, and it has been a replacement for diamonds since 1976 because of its low cost, durability and its resemblance to diamonds. Cubic zirconia is known as a “fake” diamond or CZ diamond. The following is a brief analysis of the difference between diamonds and “fake” diamonds and how they are identified.

Difference in hardness

Natural diamonds have a Mohs hardness of 10 and are difficult to process, and the cubic zirconia has a Mohs hardness of 8.5 to 9.0, while quartz sand is 7 and stainless steel is only 5.5. Therefore, the treatment of gem-level cubic zirconia can meet the requirements of daily use and is easier to process.

Differences in dispersion

The dispersion of cubic zirconia was 0.060, which is higher than that of diamond, so cubic zirconia looks more brilliant than diamonds.

The index of refraction

Cubic zirconia has a refractive index of 2.176, which is slightly lower than diamond’s 2.417. Depending on the refractive index, cubic zirconia cuts slightly differently from a diamond, which can be seen under a magnifying glass.

Color

Completely colorless diamonds are very rare, and usually, they are pale yellow. However, the cubic zirconia can be made into diamonds of the highest grade, or D-grade color. A variety of trace elements can also be added to the cubic zirconia to render it in different colors to meet customers’ demand for colored gems.

The crystals of different colors can be obtained by adding different metal oxides to the raw materials. For example, cerium: yellow, orange, red; chromium: green; neodymium: purple; erbium: pink; titanium: golden brown.

Specific gravity

Cubic zirconia is 1.7 times heavier than a diamond, so they can be distinguished by differences in specific gravity, but can only be used to separate unencrusted gems.

The heat-transfer capability

The thermal conductivity of cubic zirconia and diamond are two extremes. Cubic zirconia is a good insulator and can be used as an insulator for jet engines, while diamond is one of the best heat conducting bodies, its heat-conducting ability surpasses copper.

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