Author: Lisa K.Ross

Zirconium Carbide and Its Composite Functional Materials

Introduction

Zirconium carbide, with the chemical formula ZrC, has a theoretical carbon content of 11.64%. It belongs to the typical NaCl type face-centered cubic structure. The atomic radius ratio of C atoms and Zr atoms is 0.481, which is less than 0.59, forming a simple interstitial phase. The Zr atoms form a compact cubic lattice, and the C atoms are located in the octahedral interstitial positions of the lattice.

The melting point of zirconium carbide is 3540℃, the theoretical density is 6.66g/cm3, and the thermal expansion coefficient is 6.7×10-6℃-1. It is insoluble in hydrochloric acid, but soluble in nitric acid. Zirconium carbide is a key material for the preparation of high-performance cemented carbide, aerospace, atomic energy, textiles, electronics, coatings, hard films and metallurgical automation and other high-tech fields.

ZR1394 Zirconium Carbide (ZrC) Powder

Advantages

Zirconium carbide has the advantages of high surface activity, high temperature resistance, oxidation resistance, high hardness, good thermal conductivity, good toughness, etc., and has the characteristics of efficient absorption of visible light, a reflection of infrared rays, and energy storage. It is an important high-temperature structural material.

Using ultra-high-purity zirconium dioxide and high-purity carbon black as raw materials, and applying core technology and alloying and sintering technology to prepare, can ensure the purity, low oxygen content, and low free carbon of zirconium carbide powder. The prepared ZrC powder has densified grains, stable phase composition, uniform particle size, and stable quality.

Application

1. Zirconium carbide is added to rubber, plastics, polyethylene, acrylonitrile-butadiene-styrene copolymer ABS plastics, transparent plastics, resins, polyurethane materials, and other materials for manufacturing related products. As an additive, zirconium carbide can greatly improve the strength, high-temperature resistance, and drop resistance of plastics and related materials.

2. Adding a certain proportion of zirconium carbide to Zr-Ti alloy, C/C-(Zr-Ti-C-B/SiC) composite material, and Zr-Ti-C-B ceramic material can be made into a ceramic coating resistant to 3000℃ ablation and its composite materials. The composite material made in this way exhibits superior ablation resistance and thermal shock resistance and is a new type of material for key components of hypersonic aircraft, which is now widely used in the military and aerospace fields.

3. Zirconium carbide has the characteristics of heat absorption and heat storage. Therefore, it can be used to manufacture solid propellants in rocket engines, to produce metal zirconium and zirconium tetrachloride, and as abrasive.

4. Zirconium carbide is used for U-shaped ZrC-graphite composite ceramic combined heating element. This heating element has high heating efficiency, good energy saving effect, small occupied volume, low cold end temperature, and stable electrical performance; under vacuum, neutral or reducing atmosphere, it can provide a high-temperature environment above 2000 ℃; it has good It has excellent thermal shock resistance, high thermal efficiency, and fast heating rate, and can be raised from room temperature to 2000 ° C in 120 minutes; it can be used for thermal shock resistance test of ultra-high temperature refractory materials.

5. Zirconium carbide is used for zirconium carbide composite ceramic sensors. This sensor has high mechanical strength, is not easy to deform and volatilize at high temperatures, and has stable electrical performance and long service life; in a vacuum or protective atmosphere, it can more accurately measure ultra-high temperature ambient temperature below 3000 °C; it is the temperature sensing element with the highest temperature measurable in the contact sensor.

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Zirconium – A Vacuum Material

Properties of Zirconium

Zirconium easily absorbs hydrogen, nitrogen, and oxygen; zirconium has a strong affinity for oxygen, and oxygen dissolved in zirconium at 1000°C can significantly increase its volume. The surface of zirconium is easy to form an oxide film with luster, so its appearance is similar to that of steel. Zirconium is resistant to corrosion but is soluble in hydrofluoric acid and aqua regia. At high temperatures, zirconium can react with non-metallic elements and many metal elements to form solid solutions. Zirconium has good plasticity and is easy to be processed into plates, wires, etc. Zirconium can absorb a large amount of oxygen, hydrogen, nitrogen, and other gases when heated, and can be used as a hydrogen storage material. The corrosion resistance of zirconium is better than that of titanium, and it is close to niobium and tantalum. Zirconium and hafnium are two metals with similar chemical properties that are symbiotic together and contain radioactive substances.

Applications of Zirconium

Like lithium and titanium, zirconium can strongly absorb nitrogen, hydrogen, oxygen, and other gases. When the temperature exceeds 900 degrees Celsius, zirconium can absorb nitrogen violently; under the condition of 200 degrees Celsius, 100 grams of metal zirconium can absorb 817 liters of hydrogen, which is equivalent to more than 800,000 times that of iron. This characteristic of zirconium makes it widely used in the electric vacuum industry. People use zirconium powder to coat the surface of the anode and other heated parts of electric vacuum components and instruments to absorb residual gas in vacuum tubes. The high vacuum tubes and other electric vacuum instruments made in this way have high quality and long service life.

high vacuum tubes

Zirconium has a small thermal neutron capture cross-section and has outstanding nuclear properties, so it is an indispensable material for the development of the atomic energy industry and can be used as a reactor core structural material. Zirconium powder is easy to burn in the air and can be used as a detonator and smokeless powder. Zirconium can be used as an additive for deoxidation and desulfurization of high-quality steel and is also a component of armor steel, cannon steel, stainless steel, and heat-resistant steel.

Zirconium can also be used as a “vitamin” in the metallurgical industry to exert its powerful deoxidation, nitrogen removal, and sulfur removal effects. Adding 1/1000 zirconium to steel will increase the hardness and strength amazingly; zirconium-containing armored steel, stainless steel, and heat-resistant steel are important materials for the manufacture of defense weapons such as armored vehicles, tanks, cannons, and bulletproof panels. When zirconium is mixed into copper and drawn into copper wire, the conductivity is not weakened, while the melting point is greatly improved, which is very suitable for high-voltage wires. Zirconium-containing zinc-magnesium alloy is light and resistant to high temperatures, and its strength is twice that of ordinary magnesium alloys. It can be used in the manufacture of jet engine components.

Zirconium powder is characterized by a low ignition point and fast burning speed and can be used as a primer for detonating detonators, which can explode even underwater. Zirconium powder plus oxidant is like adding fuel to the fire, it burns with strong light and dazzling, and it is a good material for making tracer and flare.

Zirconium alloys and their applications

Zirconium alloy is a non-ferrous alloy composed of zirconium as the matrix and other elements are added. The main alloying elements are tin, niobium, iron, and so on. Zirconium alloy has good corrosion resistance, moderate mechanical properties, low atomic thermal neutron absorption cross-section in high temperature and high-pressure water and steam at 300-400 °C, and has good compatibility with nuclear fuel. In addition, zirconium alloy has excellent corrosion resistance to various acids, alkalis, and salts, and has a strong affinity with oxygen, nitrogen, and other gases, so it is also used in the manufacture of corrosion-resistant parts and pharmaceutical machinery parts. For example, it is widely used as a non-evaporable getter in the electric vacuum and light bulb industries.

zirconium alloy

There are two types of zirconium alloys produced on an industrial scale: the zirconium-tin series and the zirconium-niobium series. The former alloy grades are Zr-2 and Zr-4, and the typical representative of the latter is Zr-2.5Nb. In zirconium-tin alloys, the alloying elements tin, iron, chromium, and nickel can improve the strength, corrosion resistance, and thermal conductivity of the corrosion-resistant film, and reduce the sensitivity of the surface state to corrosion. Usually, Zr-2 alloys are used in boiling water reactors, and Zr-4 alloys are used in pressurized water reactors. In zirconium-niobium-based alloys, the corrosion resistance of the alloy is the best when the addition amount of niobium reaches the solid solution limit of the crystal structure of zirconium at the service temperature. Zirconium alloy has isomorphous transformation, the crystal structure is body-centered cubic at high temperature, and hexagonal close-packed at low temperature. Zirconium alloy has good plasticity and can be made into pipes, plates, bars and wires by plastic processing; its weldability is also good and can be used for welding.

Other Zirconium Compounds

Zirconium dioxide and zircon are the most valuable compounds in refractory materials. Zirconium dioxide is the main material of new ceramics and cannot be used as a heating material that resists high-temperature oxidation. Zirconium dioxide can be used as an additive for acid-resistant enamel and glass, which can significantly improve the elasticity, chemical stability, and heat resistance of glass. Zircon has a strong light reflection performance and good thermal stability and can be used as sunscreen in ceramics and glass. Zirconium can absorb a large amount of oxygen, hydrogen, ammonia, and other gases when heated, and is an ideal getter. For example, zirconium powder is used as a degassing agent in electronic tubes, and zirconium wire and zirconium sheets are used as grid supports and anode supports.

Powdered iron mixed with zirconium nitrate can be used as glitter powder. Zirconium metal is used almost exclusively as the cladding for uranium fuel elements in nuclear reactors. It is also used to make photographic flashes, as well as corrosion-resistant containers and pipes, especially hydrochloric and sulfuric acids. Zirconium chemicals can be used as crosslinking agents for polymers.

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Applications of Zirconium Silicate Grinding Media

Zirconium Silicate is a high-quality and inexpensive opacifier with a high refractive index of 1.93-2.01 and chemical stability. It is widely used in the production of various ceramics. Besides, Zirconium Silicate has a high melting point, so it is also widely used in refractory materials, zirconium ramming materials for glass furnaces, casting materials, and spray coatings.

The zirconium silicate media ball is one of its kind, offering users the highest quality and superior grinding levels with improved abrasion resistance, better cost-effectiveness and lower overall contamination rates. Zirconium silicate beads are formulated in strict quality-controlled laboratory containers, in which they undergo specialized instillation techniques, followed by high-temperature sintering and final surface treatment. Compared to other alternative grinding media options such as glass beads or alumina, this ultra-hard media is an ideal solution for grinding special and complex products.

Zirconium Silicate Grinding Media
Zirconium Silicate Grinding Media

The basic characteristics of a good quality zirconium silicate grinding media are that they are high in density, shiny and smooth in appearance, and consist of a uniform solid spherical shape which in turn assures better efficiencies, decreased media wear, and a much longer life span respectively. Additional specialized techniques such as solidifying the media from surface to center result in further strengthening of the molecular structure of ZrSi beads. Zirconium silicate media balls exist in varying sizes and diameters in accordance with each buyer’s prerequisites.

ZrSi04 applications and uses are tremendous and widespread from everyday products such as paints and inks to ceramics, pharmaceuticals, and even in controlled quantities within edible food materials. Zirconium Silicate grinding media plays an integral role as an emulsion agent in order to achieve a ceramic glaze in refractory’s and on cutlery etc. Also being chemically inert and nonreactive allows ZiSi04 media to be used for grinding plastic on a mass level and at economical costs. Moreover, zirconium casting refractories of all kinds utilize this media for operational purposes within glass melting furnaces, cement production and heat/fire resistant porcelain among many others. On a generalized level, Zirconium Silicate grinding media performs numerous operations including mold cleaning of stainless steel, plastic as well as nonferrous materials, mechanical polishing, buffing and eventual after-cleaning processing.

On an overall rating scale, the benefits of this industrial product being extremely dense and strong results in creating an ideal surface roughness and metallic depth with a much lower breakage or contamination rate comparatively. These attributes in turn render Zirconium Silicate milling balls suitable for application on all types of materials and within both wet and dry environments easily.

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Two Surface Treatment Technologies for Zirconium Materials

The surface of the zirconium rod and zirconium alloy must be clean and smooth before joining, heat treatment, electroplating and forming. This article introduces 2 types of surface treatment methods for zirconium materials.

  1. Surface decontamination

Grease, oil, and lubricants produced during zirconium machining or other processing can be removed in a number of ways. Commonly used cleaning methods are

1) cleaning with alkaline or milky detergent in a soaking tank;

2) cleaning with ultrasonic vibration;

3) rinsing with acetone or trichloroethylene or steam degreasing and

4) cleaning with other cleaning agents.

Small stains can also be removed by hand wiping with some solvents such as acetone, alcohol, trichloroethylene, or a trichloroethylene substitute. In the electrolyte system, if the voltage and current can be controlled to avoid anodic polarization or spark discharge and pitting, positive or negative polarity decontamination can be used. Before heat treatment and bonding, the surface of the zirconium material must be cleaned to prevent metal contamination and the resulting deterioration of ductility.

Surface Treatment Technologies for Zirconium Materials

  1. Blast cleaning

Mechanical decontamination methods such as sandblasting, shot blasting, and evaporative cleaning can remove dirt and lubricants from zirconium and hafnium surfaces. Alumina, silicon carbide, silica and steel grit are ideal media for mechanical decontamination. The decontamination medium used should be replaced regularly to avoid increased workload due to particle passivation.

Grinding or shot peening may cause residual compressive stress and thermal deformation on the surface of the material, especially the surface of the sheet. Hot deformation may also occur during subsequent rolling and profile machining.

Blast cleaning is not a substitute for pickling. Blast cleaning cannot remove surfaces contaminated with interstitial elements such as carbon, oxygen, and nitrogen. In general, blast cleaning followed by pickling can ensure the complete removal of surface contamination and cold-worked layers, resulting in a smooth, shiny metal surface.

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Application of Zirconium Silicate in Ceramic Industry

Introduction of Zirconium Silicate

Zirconium silicate is a non-toxic, odorless white powder. It is usually made of natural high-purity zircon sand concentrate, which needs to be processed by ultra-fine grinding, iron removal, titanium processing, surface modification treatment and other processes. Zirconium silicate powder is a high-quality and inexpensive ceramic glaze opacifier, brightener, anti-seepage agent and stabilizer.

Main roles of Zirconium Silicate

  1. Improve the hardness of ceramic glaze

Zirconium silicate has good chemical stability, and can significantly improve the separation performance of ceramic glaze and improve the hardness of ceramic glaze;

  1. Whitening effect

Zirconium silicate powder can whiten ceramic glazes.

Application of zirconium silicate in the traditional ceramic industry

Zirconium silicate is mainly used for high-temperature opaque glaze in daily ceramics and sanitary ware.

Application of zirconium silicate

Many companies add a small amount of zirconium silicate or zircon powder to polished tiles and glazed products to increase stability.

Another function of zirconium silicate in the traditional ceramic glaze is to increase the hardness of the ceramic glaze and improve its wear resistance of the glaze. Zirconium silicate is generally used in raw glazes with little or no zircon powder. Compared with zircon powder, zirconium silicate powder is finer and brighter.

Engobe generally uses zirconium silicate, which can increase the whiteness of the engobe and adjust its expansion coefficient and stability.

Zirconium silicate has a good effect when added to the medium and high-temperature glaze of raw materials. A certain amount of zirconium silicate is generally added to the high-gloss and matt glazes of sanitary ware and glazed porcelain tiles.

Conclusion

Zirconium silicate is a high-quality and inexpensive opacifier, which is widely used in various architectural ceramics, sanitary ceramics, daily-use ceramics, and first-class ceramics. Zirconium silicate has also been further used in the production of color picture tubes in the TV industry, emulsified glass in the glass industry, and enamel glaze production. Zirconium silicate is also widely used in refractory materials, glass furnace zirconium ramming materials, castables and spray coatings due to its high melting point.