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What is zirconium?

What is zirconium?

Zirconium is a kind of active metal, which is easy to produce oxidation reaction. If it can react with oxygen in the air at room temperature to form an oxide protective film. This protective film gives zirconium and zirconium alloys the best corrosion resistance. This oxide film can be further strengthened by heat treatment, and the surface microhardness can reach Vicat 480 (Rockwell C-scale 47). The proper treatment of the strengthened oxide film is like a good bearing surface, which can resist the corrosion of various media, bring strong wear resistance to high-speed system equipment, and also bring strong anti-corrosion ability to some highly corrosive environments. Zirconium has good corrosion resistance to reductive environment and excellent corrosion resistance to most acids. Zirconium has good corrosion resistance to less than 10% boiling sulfuric acid, 100 ℃ for 10 ~ 40% sulfuric acid, 60 ℃ for 50 ~ 60% sulfuric acid, and 35 ℃ for 70 ~ 80% sulfuric acid, only in hydrofluoric acid, concentrated sulfuric acid, aqua regia and other media. It also has good corrosion resistance to oxidizing environment such as nitric acid and chromic acid, but if there is chloride, the corrosion increases sharply. The corrosion increases sharply. In the chemical industry, it is mainly used in hydrochloric acid, molten alkali, acetic acid and other industries.

20201013050805 97089 - What is zirconium?

The following table shows the corrosion data of zirconium in acetic acid and other chemical processes

Corrosion performance table
Medium Concentration,% Temperature, Time, H Corrosion rate, mm / A
Acetic acid 5 100 144 0
25 100 144 0
50 100 144 0.0007
75 100 144 0
99.5 (without water) Boiling 144 0
Acetic anhydride 65.43% + acetic acid 34.3% + benzene 0.27% Boiling 144 0.0015
Chloroacetic acid 100 100 144 0
Dichloroacetic acid 100 100 144 0.214
Trichloroacetic acid 100 100 144 11.6

Even at low temperature, zirconium alloy has good ductility and strength similar to other engineering alloys. Oxygen is not only an indispensable component of oxide film, but also an alloy element to fill the structural gap and increase the strength of zirconium alloy. Zirconium alloy has no tendency from plasticity to embrittlement at low temperature.

Physical property

Zirconium, atomic number 40, atomic weight 91.224, silver gray metal, steel like appearance, luster, melting point 1852 ° C, boiling point 4377 ° C, density 6.49 g / cm3.

Atomic number
40
Proton number
40
Mohs hardness
4.5
Melting point
1852℃
Boiling point
4377℃
Density
6.49g/cm3
Proportion
6.49
Atomic weight
91.224
Volume
14.1 Cm3/Mol

Crystal structure: the crystal cell is a close packed hexagonal cell.
Cell parameters:

a = 323.2 pm
α = 90°
b = 323.2 pm
β = 90°
c = 514.7 pm
γ = 120°

Chemical property

Zirconium is easy to absorb hydrogen, nitrogen and oxygen; zirconium has a strong affinity for oxygen, and its volume can be significantly increased when oxygen is dissolved in zirconium at 1000 ° C. The surface of zirconium is easy to form a layer of oxide film with luster, so the appearance of zirconium is similar to that of steel. Corrosion resistant, but soluble in hydrofluoric acid and aqua regia. At high temperature, it can react with nonmetal elements and many metal elements to form solid solution. Zirconium has good plasticity and is easy to be processed into plates and wires. Zirconium can absorb a lot of oxygen, hydrogen, nitrogen and other gases when heated, so it can be used as hydrogen storage material. The corrosion resistance of zirconium is better than that of titanium, which is close to that of niobium and tantalum. Zirconium and hafnium are two metals with similar chemical properties and coexisting together, and contain radioactive substances.

CAS No
7440-67-7
Period
5
Number of families
ⅣB
Electron layer distribution
K-L-M-N-O
Peripheral electron layer arrangement
4d25s2
Extranuclear electron arrangement
2,8,18,10,2
Oxidation state
0、+1、+2+3、+4

Ionization energy (kJ / mol)

M – M
660
M – M2
1267
M2 – M3
2218
M3 – M4
3313
M4 – M5
7860
M5 – M6
9500
M6 – M7
11200
M7 – M8
13800
M8 – M9
15700
M9 – M10
17500

Zirconia

Zirconia (ZrO₂) is a kind of mineral material in nature, mainly including zircon and zircon. It can be used as the raw material of berberite, which has a strong lustre of zircon, and can be used as the raw material of berberite, which can be used as the raw material of berberite, and has the hardness of 4.4 and 4.5. Pure zirconia is a kind of high-grade refractory material. Its melting temperature is about 2900 ℃. It can improve the high-temperature viscosity of glaze and expand the temperature range of viscosity change. It has good thermal stability. When its content is 2% – 3%, it can improve the anti cracking performance of glaze. Because of its high chemical inertia, it can improve the chemical stability and acid-base resistance of glaze, and can also play the role of opacifier. Zircon is often used in building ceramic glaze, and the general dosage is 8% – 12%. Zirconia is the main raw material of “underglaze white”, and zirconia is a good auxiliary agent for yellow green pigment. In order to obtain better vanadium zirconium yellow pigment, pure zirconia must be selected.
1. Zirconia obtained by calcining zirconia hydrate or volatile zirconium oxysulfate is a white powder, insoluble in water

  • ZrO2·xH2O=ZrO2+xH2O

2. Zirconia obtained by mild burning is easily dissolved by inorganic acids

  • ZrO2+4H⁺=Zr4⁺+2H2O

The zirconia obtained by high heat calcination is only soluble in concentrated sulfuric acid and hydrofluoric acid, and the fused recrystallized zirconia only interacts with hydrofluoric acid
3. Zirconia is an amphoteric oxide, which can be fused with alkali to form zirconate.

  • ZrO2+2NaOH=Na2ZrO3+H2O
  • Na.ZrO3+H2O=ZrO2+NaOH

4. Zirconia reacts with carbon and chlorine at high temperature or with carbon tetrachloride to form zirconium tetrachloride and zirconium dichloride, and then hydrolyze to obtain zirconium dioxide

  • 3ZrO2+2C+4Cl2=ZrCl4+2CO2+2ZrOCl2

5. It reacts with carbon in an arc to form zirconium carbide

  • ZrO2+2C=CO2+ZrC

Zirconium silicate

ZrSiO4, with high refractive index of 1.93-2.01 and chemical stability, is a kind of high-quality and low-cost opacifier. It is widely used in the production of various building ceramics, sanitary ceramics, household ceramics and first-class handicraft ceramics. In the processing and production of ceramic glazes, it has a wide range of applications and a large amount of application. The reason why zirconium silicate is widely used in ceramic production is because of its good chemical stability, so it is not affected by the ceramic firing atmosphere, and can significantly improve the bonding performance of ceramic body and glaze and improve the hardness of ceramic glaze. Zirconium silicate has also been further applied in the production of color picture tubes in television industry, emulsified glass and enamel glaze in glass industry. Zirconium silicate has a high melting point of 2500 ℃, so it is widely used in refractories, zirconium ramming materials for glass furnaces, castables and spray coatings. [7]

Zirconium index

Zr index is used to measure the degree of solvent degradation in post-treatment process. 95Zr is an important kind of fragment. The higher the zirconium index, the more serious the solvent degradation. The measurement method of zirconium index (Z value) is as follows: after stripping, the organic phase is washed with sodium hydroxide, water and nitric acid, the water phase is balanced with the tracer amount of 95Zr, and the organic phase is washed with 3mol / L nitric acid for three times to remove 95Zr extracted by TBP. The amount of zirconium retained in the solvent phase was determined. The molar number of zr95 retained per 109 l of solvent was the Z value of solvent. Due to the complex behavior of zirconium in aqueous solution, the Z value will be different with different measurement conditions. Therefore, the instability coefficient is often used to characterize the stability of solvents: Goldberg Hogness box.

Isotope

There are six stable isotopes of natural zirconium: zirconium 90, 91, 92, 94 and 96, of which the content of zirconium 90 is the largest.

Isotope
Abundance
Half life period
Decay mode
Decay energy
Decay products
(MeV)
Zr-90Longest
51.45%
Stable
Nb
Zr-91
11.22%
Stable
Zr-92
17.15%
Stable
Zr-93
Man-made
1.53×10^6 Year
β decay
0.091
Zr-94
17.38%
Stable
Zr-96
2.80%
>3.8×10^19 Year
β decay
3.35

Preparation of zirconium

1. Zircon was converted into zirconium tetrachloride by calcination. Zircon and carbon are heated together to form zirconium carbide, then chlorinated to zirconium tetrachloride, and then reduced by magnesium to produce zirconium metal. The better industrial method is molten salt electrolysis with ZrCl4 or K2ZrF6 as raw materials.

  • ZrO2+3C=ZrC+2CO↑
  • ZrC+2Cl2=ZrCl4+C
  • ZrCl4+2Mg=Zr+2MgCl2

2. Zirconium carbide can be obtained by heating zircon with carbon in electric furnace, and then coarse zirconium tetrachloride can be obtained by chlorinating zirconium carbide at 500 ℃. In order to separate hafnium, crude zirconium tetrachloride was dissolved in water, and then hafnium was separated from aqueous solution. The representative method of solvent extraction and separation is to use hexanone as solvent. Hafnium oxide can be obtained by this method. Hafnium oxide is heated to 900 ℃ in the presence of carbon, and then chlorinated to form zirconium tetrachloride. Magnesium is used to reduce at about 850 ℃, and magnesium chloride can be removed by vacuum distillation at about 900 ℃. Finally, sponge zirconium is obtained.

  • ZrSiO4+3C=ZrC+SiO2+2CO↑
  • ZrC+2Cl2=ZrCl4+C
  • ZrCl4+2Mg=Zr+2MgCl2

Content distribution

The content of zirconium in the crust ranks 19th, almost equal to chromium. Zircon and zircon are the main zircon bearing minerals with industrial value in nature. Zirconium resources in the world are mainly hosted in coastal placer deposits, and only a small part of them are found in ore deposits and primary ores. The reserves of zircon sand in the world are about 40 million tons, 85% of which are distributed in Australia, South Africa, the United States, India and the former Soviet Union. The reserves of zirconium ore in China rank the ninth in the world, with a total reserves of more than 2 million tons, mainly concentrated in Guangdong, Hainan, Guangxi and Sichuan, while Yunnan is mainly composed of rock minerals. Other zirconium resources, such as Hunan, Hubei, Anhui, Fujian, Jiangxi and Liaoning, also have some zirconium resources.

Use

Industrial use

Getter

Zirconium can absorb nitrogen, hydrogen and oxygen as strongly as lithium and titanium. Zirconium can absorb nitrogen violently when the temperature exceeds nine degrees centigrade; at two degrees centigrade, one hundred grams of zirconium can absorb 817 liters of hydrogen, equivalent to more than 800000 times that of iron. This characteristic of zirconium has been widely used. For example, in the electric vacuum industry, zirconium powder is widely used to coat the anode and other heated parts of the electric vacuum components and instruments to absorb the residual gas in the vacuum tube to make high vacuum electronic tubes and other electric vacuum meters and meters, so as to improve their quality and prolong their service life.

Metallurgy

Zirconium can also be used as a “vitamin” in metallurgical industry to play a powerful role in deoxidization, nitrogen removal and sulfur removal. As long as one thousandth of zirconium is added into the steel, the hardness and strength will be dramatically improved; the armor steel, stainless steel and heat-resistant steel containing zirconium are important materials for the manufacture of national defense weapons such as armored vehicles, tanks, artillery and bulletproof plates. When zirconium is mixed into copper and drawn into copper wire, the conductivity is not weakened, but the melting point is greatly increased. It is very suitable for high voltage wire. The zinc magnesium alloy containing zirconium is light and high temperature resistant, and its strength is twice that of ordinary magnesium alloy. It can be used in the manufacture of jet engine components.
In addition, zirconium powder is characterized by low ignition point and fast combustion speed, which can be used as the primary explosive for initiating detonators, which can even explode underwater. Zirconium powder plus oxidant. It’s like fueling the fire. It burns up and glares brightly. It’s a good material for making tracer bombs and flares.

Zirconium alloy

Zirconium alloy is a nonferrous alloy with zirconium as matrix and other elements added. The main alloying elements are tin, niobium and iron. Zirconium alloy has good corrosion resistance, moderate mechanical properties and low atomic thermal neutron absorption cross section in high temperature and high pressure water and steam at 300 ~ 400 ℃, and has good compatibility with nuclear fuel. It is mostly used as core structural material of water-cooled nuclear reactor. In addition, zirconium has excellent corrosion resistance to a variety of acids, alkalis and salts, and has a strong affinity with oxygen, nitrogen and other gases. Therefore, zirconium alloy is also used to manufacture corrosion-resistant parts and pharmaceutical machinery parts, and is widely used as a non evaporable getter in the electric vacuum and bulb industry.
There are two kinds of zirconium alloys produced in industrial scale, which are zirconium tin series and zirconium Niobium Series. The alloy grades of the former are Zr-2 and Zr-4, and the typical representative of the latter is zr-2.5nb. In Zr Sn alloys, Sn, Fe, Cr and Ni can improve the strength, corrosion resistance and thermal conductivity of the film, and reduce the sensitivity of surface state to corrosion. Generally, Zr-2 alloy is used in boiling water reactor and Zr-4 alloy is used in pressurized water reactor. In the zirconium niobium series alloy, the corrosion resistance of the alloy is the best when the amount of niobium reaches the solution limit of zirconium crystal structure at the service temperature. The crystal structure of zirconium alloy is BCC at high temperature and close packed hexagonal at low temperature. Zirconium alloy has good plasticity and can be made into pipes, plates, bars and wires by plastic processing; its weldability is good and can be used for welding processing.
Zirconium has small thermal neutron capture cross section and outstanding nuclear properties. It is an indispensable material for the development of atomic energy industry and can be used as reactor core structural material. Zirconium powder is easy to burn in air and can be used as detonator and smokeless powder. Zirconium can be used as additive for deoxidation and desulfurization of high-quality steel, and is also a component of armor steel, artillery steel, stainless steel and heat-resistant steel. Zirconium is an important alloy element in magnesium alloy, which can improve the tensile strength and processability of magnesium alloy. Zirconium is also the modifier of Al Mg alloy, which can refine the grain size. Zirconia and zircon are the most valuable compounds in refractories. Zirconia is the main material of new ceramics, which can not be used as heating material for high temperature oxidation resistance. Zirconia can be used as an additive in acid resistant enamel and glass, which can significantly improve the elasticity, chemical stability and heat resistance of glass. Zircon has strong light reflection property and good thermal stability. It can be used as a light shielding agent in ceramics and glass. Zirconium can absorb a large amount of oxygen, hydrogen, ammonia and other gases when heated. It is an ideal getter. For example, zirconium powder is used as degassing agent in electronic tube, and zirconium wire and zirconium sheet are used as grid support and anode support.
Powdered iron mixed with zirconium nitrate can be used as flash powder. Almost all zirconium is used as the cladding of uranium fuel elements in nuclear reactors. It is also used to make photographic flashlights, as well as corrosion-resistant containers and pipes, especially hydrochloric acid and sulfuric acid. Zirconium chemicals can be used as crosslinking agents for polymers.

Military use

From the point of view of atomic energy and nuclear energy, zirconium is an indispensable material for the development of atomic energy industry. China’s large-scale nuclear power plants generally use zirconium materials. If nuclear power is used for power generation, 20 to 25 tons of zirconium metal will be consumed every one million kilowatts of power generation capacity. A 30000 horsepower nuclear submarine can use 20 to 30 tons of zirconium alloy as the nuclear fuel jacket and pressure tube.
Zirconium is a kind of rare metal, which is widely used in aerospace, military industry, nuclear reaction and atomic energy field because of its amazing corrosion resistance, high melting point, high hardness and strength. The corrosion resistance and high resistance titanium products used in Shenzhou-6 are far inferior to zirconium in corrosion resistance. The melting point of zirconium is about 1600 degrees, while the melting point of zirconium is above 1800 degrees, and the melting point of zirconia is even higher than 2700 degrees. Therefore, as aerospace materials, zirconium is much superior to titanium in various aspects.

Heat treatment of zirconium

Annealing

The stress relief annealing temperature of cold worked pure zirconium is about 300 ℃. The results show that the corrosion rate and the rate of hydrogen absorption decrease after annealing. After stress relief annealing, the strength of zirconium alloy changes little, but the plasticity increases obviously.

Quenching

In general, zirconium and its alloys can be hardened to a certain extent by quenching in the β zone. If the zirconium bar containing 0.02% C, 0.03% O, 0.135% Al and trace other impurities is quenched at 1000 ℃, the tensile strength increases from 269 MPa to 310 MPa, and the strength will increase after tempering at 400 ℃.

Quenching aging

It is found that zr705 is a typical alloy strengthened by quenching and aging. A large number of test results also show that heat treatment specifications strongly affect the mechanical properties and corrosion resistance of zr705 alloy, and only through heat treatment and cold working can satisfactory high strength and high corrosion resistance be obtained. The results show that the solution treatment temperature of zr705 is 880 ℃, holding for 0.5 hours, and then quenching. The Vickers hardness value is 245 ± 5kg / mm after quenching. The aging temperature is usually 500 ℃. The hardness of the alloy increases in the first 3-6 hours, and then maintains at the maximum value of 265 ± 7kg / mm (Vickers hardness). If aging at lower 300 ℃ and 400 ℃, the hardness peak value will be slowly reached. Zirconium and zirconium alloy products harden rapidly. The residual stress can be relieved by heat treatment at 565 ℃ for half an hour to one hour.

Source: China Flanges Manufacturer – Yaang Pipe Industry (www.epowermetals.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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20201013130744 - What is zirconium?
Article Name
What is zirconium?
Description
Zirconium is a kind of active metal, which is easy to produce oxidation reaction.
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  1. […] The symbol of zirconium is Zr, which is located in the IV-B group of the periodic table. It is a silver-white metal. It has a high melting point, a moderate density, good strength and plasticity matching, and a small thermal neutron absorption cross-section. It is an important structural material for the nuclear industry. Zirconium, like titanium, has excellent corrosion resistance in many acid and alkali media. Therefore, zirconium is an excellent chemical corrosion-resistant structural material. […]

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